U.S. patent application number 10/630929 was filed with the patent office on 2004-04-15 for plasma display panel, manufacturing method and manufacturing apparatus of the same.
This patent application is currently assigned to TOPPAN PRINTING CO., LTD.. Invention is credited to Akimoto, Yasumasa, Arai, Junichi, Kato, Isao, Minato, Takao, Nakamura, Ryuichi, Nishimura, Ikuma, Ohira, Katsumi, Ohno, Naoto, Watanabe, Eizaburo.
Application Number | 20040070342 10/630929 |
Document ID | / |
Family ID | 27288261 |
Filed Date | 2004-04-15 |
United States Patent
Application |
20040070342 |
Kind Code |
A1 |
Watanabe, Eizaburo ; et
al. |
April 15, 2004 |
Plasma display panel, manufacturing method and manufacturing
apparatus of the same
Abstract
A method of manufacturing a plasma display panel, which
comprises the steps of filling a barrier rib-forming paste
containing glass frit in a barrier ribs-forming intaglio and
concurrently forming a paste layer having a constant thickness on
the intaglio, superimposing a substrate on the barrier ribs-forming
intaglio filled with the barrier rib-forming paste containing glass
frit to thereby transfer the barrier rib-forming paste onto the
substrate, and heating the barrier rib-forming paste that has been
transferred to the substrate, thereby burning out existing organic
components and concurrently sintering the glass frit to thereby
form the barrier ribs and dielectric layer. The plasma display
panel manufactured by this method is featured in that the barrier
ribs and the dielectric layer are formed using the same barrier
rib-forming material containing a low melting point glass frit.
Inventors: |
Watanabe, Eizaburo; (Tokyo,
JP) ; Ohno, Naoto; (Tokyo, JP) ; Ohira,
Katsumi; (Tokyo, JP) ; Arai, Junichi; (Tokyo,
JP) ; Kato, Isao; (Tokyo, JP) ; Akimoto,
Yasumasa; (Tokyo, JP) ; Nishimura, Ikuma;
(Tokyo, JP) ; Minato, Takao; (Tokyo, JP) ;
Nakamura, Ryuichi; (Tokyo, JP) |
Correspondence
Address: |
STAAS & HALSEY LLP
SUITE 700
1201 NEW YORK AVENUE, N.W.
WASHINGTON
DC
20005
US
|
Assignee: |
TOPPAN PRINTING CO., LTD.
TOKYO
JP
|
Family ID: |
27288261 |
Appl. No.: |
10/630929 |
Filed: |
July 31, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10630929 |
Jul 31, 2003 |
|
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|
09925648 |
Aug 10, 2001 |
|
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6632116 |
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09925648 |
Aug 10, 2001 |
|
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PCT/JP00/00760 |
Feb 10, 2000 |
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Current U.S.
Class: |
313/586 |
Current CPC
Class: |
C03C 2217/452 20130101;
C03C 2217/485 20130101; C03C 17/02 20130101; C03C 17/007 20130101;
Y02P 40/57 20151101; H01J 2211/36 20130101; H01J 9/242 20130101;
G02F 1/13334 20130101; C03C 2217/475 20130101; C03B 19/06 20130101;
C03C 2217/44 20130101 |
Class at
Publication: |
313/586 |
International
Class: |
H01J 017/49 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 12, 1999 |
JP |
11-033932 |
Nov 9, 1999 |
JP |
11-318127 |
Nov 10, 1999 |
JP |
11-319687 |
Claims
What is claimed is:
1. A plasma display panel comprising: a back substrate; electrodes
each formed in a region partitioned; barrier ribs arranged on said
back substrate and partitioning said region; and a dielectric layer
covering said electrodes, wherein said barrier ribs and said
dielectric layer comprise the same barrier rib-forming material
containing a low melting point glass frit, and a film thickness of
said dielectric layer is in a range of 5 to 50 .mu.m.
2. The plasma display panel according to claim 1, wherein a film
thickness of said dielectric layer is in the range of 5 to 20
.mu.m.
3. A plasma display panel comprising: a back substrate; electrodes
each formed in a region partitioned; and barrier ribs arranged on
said back substrate and partitioning said region, wherein said
barrier ribs are formed of a recessed structure comprising a bottom
structure contacting with said back substrate, and an upper
structure projected from said bottom structure; and said electrodes
are each disposed at the bottom of said recessed structure.
4. The plasma display panel according to claim 3, wherein the
visible light reflectivity of the regions other than the electrodes
is 50% or more under the condition where a phosphor is not
coated.
5. The plasma display panel according to claim 3, wherein a
recessed portion is formed at the bottom of the opening portion of
the recessed structure, and the electrode is disposed at this
recessed portion.
6. The plasma display panel according to claim 3, wherein the width
of the recessed portion is the same in size as the bottom of the
opening portion of the recessed structure.
7. The plasma display panel according to claim 3, wherein the
thickness of the bottom of the recessed structure is larger than
the width of the upper structure of recessed portion.
8. A back plate of plasma addressed liquid crystal display panel
comprising: a back substrate; a transparent dielectric layer formed
on said back substrate; transparent barrier ribs arranged on said
transparent dielectric layer and comprising the same material as
that of said transparent dielectric layer; an anode formed on said
transparent dielectric layer; and a cathode formed on said
transparent dielectric layer; wherein a film thickness of said
transparent dielectric layer is in a range of 3 to 15 .mu.m.
9. The back plate of plasma addressed liquid crystal display panel
according to claim 8, wherein an angle between a sidewall of the
transparent barrier rib and said back substrate is in a range of 85
to 95 degrees.
10. The back plate of, plasma addressed liquid crystal display
panel according to claim 8, wherein a surface roughness of the
sidewall of the transparent barrier rib is 1 .mu.m or less and is
equivalent almost to an optical flat surface.
11. A plasma display panel comprising: a back substrate; and
barrier ribs arranged on said back substrate, wherein said barrier
ribs are formed of a recessed structure comprising a bottom
structure contacting with said back substrate, and an upper
structure projected from said bottom structure; and visible light
reflectivity of the back substrate is 50% or more under a condition
where a phosphor is not coated.
12. A plasma display panel comprising: a back substrate; and
barrier ribs arranged on said back substrate, wherein said barrier
ribs are formed of a recessed structure comprising a bottom
structure contacting with said back substrate, and an upper
structure projected from said bottom structure; and a thickness of
the bottom structure of the recessed structure is larger than a
width of the upper structure of the recessed structure.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This is a Divisional of application Ser. No. 09/925,648
filed Aug. 10, 2001, which is now allowed, which is a Continuation
Application of PCT Application No.PCT/JP00/00760, filed Feb. 10,
2000, which was not published under PCT Article 21(2) in
English,
[0002] This application is based upon and claims the benefit of
priority from the prior Japanese Patent Applications No. 11-033932,
filed Feb. 12, 1999; No. 11-318127, filed Nov. 9, 1999; and No.
11-319687, filed Nov. 10, 1999, the entire contents of all of which
are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention.
[0004] The present invention relates to a plasma display panel, and
to the method and apparatus for manufacturing the plasma display
panel. In particular, the present invention relates to a plasma
display panel which is provided with barrier ribs for partitioning
the discharge region of the plasma display panel, and to the method
and apparatus for manufacturing such a plasma display panel.
[0005] 2. Description of the Related Art
[0006] Conventionally, a CRT has been extensively employed as an
image display device. However, the CRT is defective in the respects
that it is large in overall size and weight, and that it requires a
high voltage. Under the circumstances, a flat type image display
device such as a light emitting diode (LED), a liquid crystal
display device (LCD), a plasma display panel (PDP), a plasma
addressed liquid crystal display (PALC), etc. has been developed in
recent years, and these devices are now increasingly utilized.
[0007] Among them, due to the propagation of multimedia, the plasma
display panel which is adapted to be employed as an interface of
information in a color display device of large image area is now
noticed as promising because the structure thereof where the
emission of plasma is utilized is simple, it is suited for
achieving a large image area and an excellent image quality, it is
light in weight, and it is thin-walled so that it is free from
restriction regarding the installation place thereof.
[0008] This plasma display panel comprises discharge display cells
having minute spaces which are encircled by barrier ribs
partitioning a space formed between a pair of flat insulating
substrates, wherein each of the discharge display cells is provided
therein with a pair of discharge electrodes and an address
electrode which is disposed at the bottom of the discharge display
cell. The minute spaces of the discharge display cells are formed
of an air-tight structure filled therein with a dischargeable gas
such as a rare gas, thereby enabling a plasma to be generated in
the spaces through the discharging between the discharge electrodes
and the address electrode, wherein the switching of light emission
of the discharge display cells is effected by the address
electrode.
[0009] The plasma can be generated by selectively applying a
voltage between facing discharge electrodes, and vacuum ultraviolet
rays released from the plasma are utilized for generating light
from the phosphors formed within the discharge display cells,
thereby making it possible to utilize the discharge display cells
as the light-emitting elements of image display device.
[0010] Therefore, it is required, for the performing the
aforementioned switching, to apply a voltage between the discharge
electrodes. However, if the electrostatic capacity of the discharge
display cell is large, the driving current between the discharge
electrodes is rendered to be increased. As a result, the power
consumption of the plasma display panel is required to be
increased, thereby raising a problem that the power source
equipment of the plasma display panel is required to be
enlarged.
[0011] Further, although the plasma display panel constructed as
described above is simple in structure, and suited for enhancing
the fineness of image, each of the electrodes and phosphors
disposed inside the discharge display cells is permitted to be
exposed directly to the plasma being generated. As a result, due to
the sputtering effect of the plasma, the surfaces of these
electrodes and phosphors are deteriorated, thereby raising a
problem that the light emission efficiency of the display panel is
liable to be decreased.
[0012] With a view to overcome these problems, there has been
proposed a plasma display panel wherein a dielectric layer is
formed on the opposing electrodes disposed inside the discharge
display cell to thereby protect the surface of each electrode with
this dielectric layer, thereby making it possible to reduce the
electrostatic capacity of the discharge display cell and to prevent
the electrodes and phosphors from being deteriorated by the plasma
generated (Jpn. Pat. Appln. KOKAI No. H8-77930; and Jpn. Pat.
Appln. KOKAI No. H7-57630).
[0013] As for the method of forming a dielectric layer of uniform
thickness on the address electrodes of discharge display cell,
there is generally known a method wherein a dielectric paste is
printed, and the uniformity of thickness and the flatness of the
printed layer are enabled to be achieved through the leveling
effect of the surface of printed paste.
[0014] However, even if a dielectric paste of low fluidity is
employed, with a view to ensure a uniform thickness and flatness of
a dielectric layer, for forming a dielectric layer having a
thickness of about 5 .mu.m on an electrode pattern ordinarily
having a thickness of about 10 .mu.m, the surface of the dielectric
layer to be obtained would become wavy due to the recessed and
projected surface constituted by regions where the electrode
pattern is existed and regions where the electrode pattern is not
existed, thereby making it difficult to obtain a dielectric layer
which is uniform in thickness.
[0015] On the other hand, if a dielectric paste having a high
leveling property, i.e. excellent in fluidity is employed with a
view to ensure the flatness of dielectric layer, it would become
difficult to secure a sufficient thickness of the dielectric layer
as it is formed on the address electrode, thereby possibly
permitting part of the address electrode to be exposed to the
outside. Thus, the thickness of the dielectric layer would become
non-uniform, thus making it very difficult to obtain a dielectric
layer which is uniform in thickness and excellent in flatness.
[0016] Therefore, since the thickness or flatness of the dielectric
layer formed on the surface of address electrode becomes
non-uniform as mentioned above, the quantity of electric charge to
be stored in the dielectric layer is caused to differ depending on
the regions thereof. As a result, a voltage for controlling the
emission of light is caused to differ for each of the discharge
display cells depending on the location thereof, thereby raising a
problem that it is impossible for the address electrode disposed
between the barrier ribs to display a stable and accurate light
emission.
[0017] Furthermore, the forming of the dielectric layer by means of
printing method leads to an increase in number of steps by one
additional step in the manufacture of the back plate of plasma
display panel. Furthermore, since the material for forming the
barrier rib differs from the material for forming the dielectric
layer, there is a room for improvement not only in terms of
productivity but also in terms of material cost.
[0018] There has been also proposed, as a method of forming the
barrier rib integral with the dielectric layer, a press molding
method wherein the material for forming the barrier rib is
press-molded by making use of an intaglio having a pattern of the
barrier ribs. Although it is required, in this case, to control the
thickness of the dielectric layer through the adjustment of gap
between the intaglio and the substrate, the provision of the gap
makes it difficult to obtain a sufficient pressing pressure, and
still more, it is difficult to precisely fit the barrier
rib-forming material into the aforementioned intaglio of barrier
rib-like configuration.
[0019] Additionally, the provision, in advance, of the
thickness-wise configuration of the dielectric layer in the
intaglio is difficult in the aspect of working the intaglio.
Further, if there is a wavy portion in thickness-wise in the glass
substrate or any non-uniformity in the pressing pressure to the
intaglio, it becomes difficult to make constant the gap between the
intaglio and the substrate, thus failing to obtain the dielectric
layer having a uniform thickness.
[0020] The barrier ribs for constituting the discharge display cell
are formed of an insulating material, e.g. an inorganic metal
oxide, in general, which is bound by lead glass. As for the
specific method of fabricating the barrier rib, there are known
various method. At present however, the sand blast method is mainly
employed (as for the conventional method of fabricating the barrier
rib, see a monthly publication; Kameya, "LCD intelligence", 1997,
August, pp 57).
[0021] This sand blast method is featured in that a barrier
rib-forming material is coated on a substrate to a predetermined
thickness, and after predetermined regions of the coated layer
which are desired to be left have been masked, sand is blasted onto
the coated layer to thereby cut away redundant portions of the
barrier rib-forming material, thereby forming a barrier rib.
[0022] Generally, barrier ribs, dielectric materials and
electrodes, which are constituent elements for the discharge
display cell, are formed on the back substrate.
[0023] According to the conventional manufacturing process, a back
substrate as shown in FIG. 1 is manufactured by a sequence of
steps, i.e. (1) a step of forming electrodes 2 on a glass substrate
1; (2) a step of forming a dielectric layer 3 on the surface of the
electrodes 2; and (3) a step of forming barrier ribs 4 on the
surface of the dielectric layer 3 (i.e. the electrodes 2.fwdarw.the
dielectric layer 3.fwdarw.the barrier ribs 4).
[0024] Since each of these steps accompanies a substrate-sintering
step, the dimension of the substrate is caused to vary on every
occasions of these steps.
[0025] Therefore, when a strict dimensional accuracy is demanded
for the purpose of enhancing the fineness of display cells, a
problem is raised in the respect that the alignment between the
electrodes and the barrier ribs becomes increasingly difficult due
to the dimensional changes of substrate resulting from the
sintering of the substrate.
[0026] Further, when the pitch of pixel becomes narrower, a
defective such as short circuit between electrodes in the step of
forming electrodes is liable to be generated, thus raising a
problem.
[0027] By the way, although the barrier ribs are generally formed
as an independent column, respectively, it is increasingly demanded
to make the width of barrier rib narrower in order to increase the
aperture ratio as the display is required to be further enhanced in
fineness and in precision.
[0028] In this case, a problem is raised in that when the barrier
ribs are formed into an independent column, respectively, the
narrower the width of barrier rib becomes, the more it becomes
likely that the barrier rib tends to fall down.
[0029] When it is desired to enhance the luminescence intensity of
each pixel, it can be realized by enhancing the luminescence
intensity of the phosphor itself. Alternatively, the light to be
emitted from the phosphor may be reflected so as to increase the
quantity of light to be emitted outside.
[0030] In order to realize this, it is preferable that the barrier
rib to be formed on the back substrate is produced by making use of
a white material which is excellent in reflectivity, and at the
same time, a white dielectric material is formed also on the
electrodes interposed between the barrier ribs, thereby enhancing
the reflectivity of the substrate as high as possible.
[0031] Further, the thickness of the dielectric material should
preferably be such that the permeation of visible light to the rear
surface of substrate can be inhibited.
[0032] However, the thickness of the dielectric material will be
restricted by the driving voltage, i.e. when the thickness of the
dielectric material is increased, the driving voltage will be
required to be proportionally increased. In view of this problem,
the thickness of the dielectric material is in the range of 10 to
15 .mu.m in general.
[0033] Accordingly, there is a problem that it is impossible,
according to the plasma display that has been manufactured by
making use of the aforementioned back substrate, to obtain a
satisfactory brightness, because most of emitted light is permitted
to permeate toward the rear surface of the back substrate.
[0034] On the other hand, as for the thin display apparatus of
large image area, a 25-inch plasma addressed liquid crystal display
is placed on the market, and a 42-inch plasma addressed liquid
crystal display is also exhibited in an exhibition (S. Fukusue;
"Manufacturing Process of PALC", a monthly publication, "FPD
intelligence", vol. 6 (1998), pp 79-83).
[0035] In the manufacture of the plasma addressed liquid crystal
display panel which is actually employed as described above, a
process mainly utilizing a thick film printing method as disclosed
in Jpn. Pat. Appln. KOKAI No. H4-265931 is adopted, thereby making
it suited for the mass-production as well as for the production of
panel having a large image area.
[0036] FIGS. 2 and 3 illustrate one example of this conventional
plasma addressed liquid crystal display panel. As shown in FIGS. 2
and 3, after an anode 11 and cathode 12 are formed on the surface
of a plasma substrate 10, barrier ribs 13 are formed on the
substrate 10. Thereafter, the resultant body is sealed by making
use of a dielectric thin glass plate 14 and by way of frit glass
sealing. After this sealed body is evacuated, a discharge gas is
introduced therein. After a CF layer 16 consisting of R, G and B,
and a black stripe 17 are successively formed on a CF substrate 15,
a signal electrode 18 is formed thereon. Then, the plasma substrate
10 and the CF-attached glass substrate 15 are arranged to oppose to
each other with a spacer being interposed therebetween, and then, a
liquid crystal 19 is further introduced thereinto. Finally, a
polarizing plate 20 and a back light 21 are disposed in place to
accomplish the fabrication of the plasma addressed liquid crystal
display panel.
[0037] Next, the structure of the conventional plasma addressed
liquid crystal display panel which is related to the present
invention as well as the manufacturing method thereof will be
explained with reference to FIG. 3 where the structure of the panel
is shown and to FIG. 4 where the manufacturing steps of the panel
are shown. By the way, in the case of a 42-inch plasma addressed
liquid crystal display panel, the pitch of barrier ribs is set to
1.092 mm.
[0038] First of all, a low expansion coefficient glass substrate
provided with an exhaust pipe-connecting hole is washed and dried.
Then, by means of screen printing method, a Ni electrode paste is
coated on the entire surface on the structure and then, dried to
form a Ni electrode layer having a thickness of 50 .mu.m. The Ni
electrode paste in this case is mainly composed of a Ni metal
powder, a low melting point glass, an antioxidant, a binder resin
which is excellent in pyrolizability (ethyl cellulose, etc.), and a
solvent for providing an excellent rheological property for screen
printing (butyl acetate carbitol, .alpha.-terpineol, etc.).
Thereafter, a dry film (DF) is adhered onto the electrode layer,
and patterned by way of exposure and development. Then, by means of
sand blast method, redundant portions of the Ni electrode material
are removed and the DF is peeled away. As a result, a stripe-shaped
Ni electrode pattern corresponding to the anode and cathode for a
discharging space is obtained. Further, since it is difficult to
perform a vacuum sealing in this structure having the Ni electrode,
a Ag electrode paste is further coated, by means of screen printing
method, for use for the sealing portion and for the terminal
electrode portion. By the way, for the purpose of preventing the
generation of abnormal discharging at an end portion of plasma
channel, a cover glass paste is coated by means of screen
printing.
[0039] Thereafter, a barrier rib-forming paste for forming a
barrier rib of plasma cell is repeatedly coated and dried several
times by means of screen printing method until the resultant
laminated structure becomes as high as about 250 .mu.m in
thickness, the resultant paste layer being subsequently baked. The
barrier rib-forming paste in this case is mainly composed of a low
melting point glass, a binder resin which is excellent in
pyrolizability (ethyl cellulose, etc.), a solvent for providing an
excellent rheological property for screen printing (butyl acetate
carbitol, .alpha.-terpineol, etc.), and a black pigment. By the
way, the purpose for adding a black pigment to the barrier
rib-forming paste is to make the barrier rib black in color after
the sintering thereof and hence to prevent light from being
reflected from the sidewall of barrier rib as explained below.
Finally, the top portion of the barrier rib is polished so as to
control the height of barrier rib to 200 .mu.m.+-.2 .mu.m and to
flatten the top surface of barrier rib. Thereafter, the barrier rib
is fully washed so as not to leave any residual materials after the
polishing. By the way, the dimension of the Ni electrode after the
sintering of the barrier rib is about 40 .mu.m in thickness and
about 100 .mu.m in width. Further, the resistance of the barrier
rib with about 1000 mm of the discharge portion thereof is about
500.OMEGA..
[0040] Since this Ni electrode is not formed of pure metal but
formed of a glass cermet consisting of a metal and a low melting
point glass frit, the electric resistance after sintering is at
least 20 times as high as that of metal Ni. Therefore, the
electrode cannot be made narrower in width and thinner in
thickness. Since the width of the electrode cannot be made
narrower, the aperture ratio cannot be reduced, thereby
deteriorating the utilization efficiency of light emitted from the
back light. Further, since the aperture ratio becomes 40% or less,
it will become a decisive defect for the barrier ribs whose pitch
is set to 0.485 mm as in the case of the 42-inch HDTV
specification.
[0041] Further, since the thickness of the Ni electrode after the
sintering thereof is set to about 40 .mu.m, it will become
difficult to uniformly laminate a dry film (DF) on the surface of
the substrate. As a result, it becomes difficult to employ a
paste-burying method wherein the height and configuration of the
top of the barrier rib can be easily controlled by adjusting the
thickness of the DF.
[0042] On the other hand, the method of forming the barrier rib by
means of a sand blast method which has been proven to be useful for
mass production in the method of forming the barrier rib of an AC
type plasma display panel (PDP) is advantageous in that since the
electrodes of plasma display panel are covered with a dielectric
layer, the electrodes can be prevented from being damaged by the
sand blast on the occasion of forming the barrier rib. However,
since the electrodes are left exposed in the case of the PALC, the
electrodes may be damaged by the sand blast, and hence this method
is not so suited for use, and in fact, this method is not actually
employed.
[0043] Under the circumstances, the screen printing method which is
somewhat defective in terms of dimensional precision is compelled
to be employed in the production of the barrier rib. In this case,
if the pitch of the barrier ribs is set to 1.092 mm as in the case
of the 42-inch VGA specification, a sufficient margin can be
secured, thereby making it possible to form the barrier rib between
electrodes. However, if the pitch of the barrier ribs is to be set
to 0.485 mm as in the case of the 42-inch HDTV specification, an
alignment precision within the range of .+-.10 .mu.m is required,
and hence this method is decisively defective in this respect.
[0044] As explained above, black barrier ribs are employed in the
conventional structure of display panel. The purpose of providing
the black barrier ribs is to suppress the influence of the
deterioration of contrast that will be induced by the stray light
which is reflected from the sidewall of the barrier rib. As a
result, the light is shielded by the black barrier ribs and hence
the aperture ratio is restricted, thus inviting a decisive defect
that it is difficult to enhance the utilization efficiency of the
backlight.
[0045] There is another problem that even if a liquid crystal of
wide viewing angle mode is employed, the advantages thereof cannot
be fully utilized due to so-called louver effects where the viewing
angle is restricted in the direction perpendicular to the black
barrier rib. With a view to overcome this problem, Jpn. Pat. Appln.
KOKAI No. H11-212068 proposes a novel structure of plasma addressed
liquid crystal display panel where the following measures are
adopted.
[0046] Transparent barrier ribs are formed in place of the
aforementioned black barrier ribs. It is possible, with this
structure, to prevent the narrowing of viewing angle to be induced
by the louver effects. When the transparent barrier ribs are formed
of a material whose surface is relatively smooth, the deterioration
of contrast due to the scattering of light can be suppressed.
Further, if it is constructed such that the polarizing plate
arranged close to the back glass substrate is disposed in such a
manner that the direction of transmission axis thereof is oriented
at an angle of 0 degree or 90 degrees to the direction of the
transparent barrier rib; that the polarizing plate arranged close
to the front glass substrate is disposed in such a manner that the
direction of transmission axis thereof is oriented orthogonal to
the transmission axis of the polarizing plate arranged close to the
back glass substrate; and that the transparent barrier ribs are
erected perpendicular to the back glass substrate, the rotation of
light on polarization plane can be prevented on the occasion when
the light passes through the transparent barrier rib.
[0047] It is said that as a result of the structure as mentioned
above, it becomes possible to obtain a panel which is excellent in
utilization efficiency of backlight, without deteriorating the
contrast, and wide in viewing angle as compared with the
conventional panel having the black barrier ribs.
[0048] However, this manufacturing method of the back glass
substrate is substantially the same as the aforementioned method of
manufacturing the barrier rib substrate of plasma addressed liquid
crystal display by means of the conventional thick film printing
method. Namely, this manufacturing method is simply featured in
that a glass paste for forming a transparent barrier rib is
substituted for the glass paste for forming a transparent barrier
rib. Therefore, this manufacturing method is accompanied with the
same decisive defect as mentioned above.
[0049] Further, as apparent from the aforementioned manufacturing
technique of plasma display, the conventional method of forming the
barrier rib through a repetition of the thick film printing method
is accompanied with a problem that in what manner the Theological
property of the barrier rib-forming paste is controlled, it is
unrealistic, even if it may be possible in the level of laboratory,
to vertically erect the barrier rib up to a height of as high as
250 .mu.m on the surface of glass substrate. It is much less
possible to uniformly erect vertical barrier ribs up to a height of
as high as 250 .mu.m on the surface of glass substrate of 42 inches
in size. Additionally, it is difficult to take measures to a
problem of stepped portions which may be formed on the sidewall of
barrier rib due to the repetition of the printing procedure.
[0050] As mentioned above, there has been proposed, as a method of
forming the barrier rib integral with the dielectric layer, a
method of press-molding a material for the barrier rib by making
use of an intaglio having a configuration of the barrier rib. This
method of forming a projection pattern by making use of such an
intaglio is accompanied with the following problems as explained
below.
[0051] A first problem to be raised on the occasion of forming a
projected pattern on a rigid substrate by making use of an intaglio
is that since the intaglio is also formed of a rigid material, an
insufficiently contacted portion may be generated at the interface
between the intaglio and the rigid substrate. As a result, the
transfer of ink from the intaglio to a printing matter (matter to
be printed) this insufficiently contacted portion, thereby
generating a defective portion indicating a transfer failure. Jpn.
Pat. Appln. KOKAI No. H4-34551 discloses a method for overcoming
this problem. This method is directed to the transfer of a pattern
to a glass substrate, etc., wherein an ink-repellent elastic layer
is formed all over the surface of the intaglio excluding the
recessed portions thereof. At the time of printing, this elastic
layer is deformed by the printing pressure, thereby enabling the
elastic layer to be closely contacted with a rigid substrate such
as a glass substrate which may be non-uniform in thickness or
uneven in surface state, thus permitting ink to transfer from the
intaglio to the substrate. As a result, a pattern which is minimal
in defects is said to be obtained.
[0052] Though it may depend on the viscosity of ink, ink is caused
to split at approximately half a depth of the intaglio at the
transferring step thereof, so that a projected pattern to be
obtained is of reduced thickness. Additionally, the configuration
of the projected pattern thus obtained is also influenced by the
splitting of ink.
[0053] Meantime, Jpn. Pat. Appln. KOKAI No. S57-87318 discloses a
method for preventing the generation of the splitting of ink.
Namely, this method is featured in that the ink (paste) to be
employed therein is formed of an ultraviolet-curing composition or
of an electron beam curing composition, and hence the ink held in
the intaglio is preliminarily cured before it is transferred. It is
also disclosed therein that for the purpose of enhancing the
releasability of intaglio, silicone is applied to the interior of
intaglio.
[0054] Further, Jpn. Pat. Appln. KOKAI No. H4-35989 discloses a
method which seems to be a modification of the method disclosed in
Jpn. Pat. Appln. KOKAI No. H4-34551. Namely, this method is
featured in that the inner surface of the recessed portions is
constituted by a releasable material such as silicone rubber or
Teflon, thereby improving the transferability of ink. Therefore, if
an adhesive layer is deposited in advance on the surface of a rigid
printing matter such as a glass substrate, the transfer of ink can
be performed after the curing of ink, thereby enabling to obtain a
projected pattern exhibiting an excellent configuration.
[0055] However, there is a problem that since the inner surface of
the recessed portions is constituted by an ink-repellent surface or
by a releasable surface, the ink that has been once introduced into
the recessed portions may be removed from the recessed portions and
adhered to an inking roller, as the inking roller is separated away
from the intaglio.
[0056] The technique disclosed in this Jpn. Pat. Appln. KOKAI No.
H4-35989 is a modification of the printing plate and of the
printing method disclosed in Jpn. Pat. Appln. KOKAI No. S56-137989.
According to the latter publication, the surface of printing plate
is not provided with an ink-repellent layer, but is constituted by
a hard material such as a chrome plating layer or a stainless steel
plate. In this case, even if the inner surface of the recessed
portions is poor in conformability with ink, it has been possible
to enable the inner surface of recessed portion of the hard layer
to become compatible with ink and hence to perform the inking,
provided that the inking is performed by making use of a doctor
blade. Since the backing material is expandable, the backing
material is capable of pushing out ink as it is pressed, so that
the transfer of ink to the rigid substrate can be performed without
raising any serious problem. Further, since the ink can be cured
before it is discharged from the printing plate so as to shape the
ink into a desired configuration, it has been possible to push out
the resultant cured ink toward a printing matter as mentioned
above. However, it has been impossible to apply an adhesive
material to the surface of printing matter in the transfer of ink
to the printing matter, because if an adhesive material applied to
the surface of printing matter, the printing plate will be bonded
to the printing matter.
[0057] If silicone resin or fluororesin is applied, for the purpose
of avoiding the aforementioned problem, to the surface of printing
plate so as to make the surface of printing plate releasable to ink
or an adhesive material, there will be raised another problem that
since these resins are soft, these resins are liable to be damaged
on the occasion of scraping out ink by means of doctor blade, and
hence the durability of the printing plate becomes poor.
[0058] Jpn. Pat. Appln. KOKAI Nos. H4-10936 and H5-241175 set forth
a method for modifying the aforementioned inking method. Namely,
this method is featured in that ink is pushed into the recessed
portions by making use of a film exhibiting an excellent
releasability. According to this method, irrespective of whether
the ink in the recessed portions is cured or not, there is no
possibility that the ink in the recessed portions is wiped out or
taken up by the inking roll.
[0059] However, these Japanese Patent Publications simply set forth
the methods of inking and curing, but nothing about the apparatus
thereof. Further, there is another problem which may be raised on
the occasion of inking to the recessed portions. Namely, the
problem is the entrapment of air bubbles, which is more likely to
occur as the depth of the recessed portions becomes deeper, the
pattern becomes finer, the viscosity of ink becomes higher, and the
filling speed becomes faster. The aforementioned Japanese Patent
Publications however suggest nothing about these problems.
[0060] Next, the method of continuously manufacturing the barrier
ribs of flat plasma display panel using a rotary type apparatus
type will be explained. As for the prior art, Jpn. Pat. Appln.
KOKAI Nos. H8-321258 and. H10-101373 set forth a technique related
to this.
[0061] The method disclosed in Jpn. Pat. Appln. KOKAI No. H8-321258
will be explained with reference to FIGS. 5 to 7, wherein the
following two steps are essentially required.
[0062] (1) By making use of an intaglio 54 provided with recessed
portions 71 for forming the barrier rib portions of plasma display
panel, an ionizing radiation-curing resin 53 containing glass frit
is filled at least in the recessed portions 71 of the intaglio 54,
and at the same time, a film substrate 61 is permitted to contact
with the intaglio 54, during which an ionizing radiation 51 is
irradiated to the ionizing radiation-curable resin 53 which is kept
interposed between the film substrate 61 and the intaglio 54 to
thereby cure the resin 53, after which the film substrate 61 and
the resin 53 are released away from the recessed portions 71.
[0063] (2) The surface of ionizing radiation-curable resin thus
cured, having the configuration of barrier ribs and formed on the
film substrate 61 is closely contacted with the surface of the
substrate of plasma display panel, and then, subjected to a
sintering step.
[0064] Namely, for the purpose of obtaining a desired configuration
of barrier ribs, this desired configuration is formed on a film
substrate at first in the step (1); and then, the configuration
formed on a film substrate is transferred to a glass substrate.
[0065] The aforementioned manufacturing method is accompanied with
the following problems.
[0066] (1) Since the configuration of barrier ribs is formed on a
film at first, and then, the configuration of barrier ribs is
transferred, it is very difficult to secure the positional
precision (dimensional precision). Because the barrier ribs are
required to be aligned with an electrode to interposed between
these barrier ribs, and a positional precision of about .+-.2-10
.mu.m/m is required.
[0067] Referring to FIG. 5, the longitudinal direction of the
barrier ribs is orthogonally intersected with the longitudinal
direction of the film. Accordingly, if the barrier ribs are to be
formed in the direction shown in FIG. 5, the precision of the
barrier ribs is directly influenced by the shrinkage and expansion
of the film, so that in the case of polyester film to be employed
in the example for example, the expansion of the polyester film is
required-to be adjusted through a precise tension control in the
longitudinal direction thereof on the occasion of transferring to
thereby adjust the pitch of the barrier ribs.
[0068] Further, even if the barrier ribs are to be formed in the
orthogonally intersecting direction as shown in FIG. 5, i.e. in the
direction where the longitudinal direction of the barrier ribs is
coincide with the longitudinal direction of the film, a precise
tension control in the lateral direction thereof is required. In
this case, the tension control in the longitudinal direction of the
film is also required for preventing the generation of defects such
as a disconnection of barrier ribs, etc. It is also difficult to
carry out the winding of film. As shown in FIG. 6, the film should
most preferably be disposed flat after finishing the transferring
of the barrier ribs on the film.
[0069] (2) Although the configuration of the barrier rib should
preferably be trapezoidal as it is viewed from the back substrate
side, if the configuration of the barrier rib is such as shown in
FIGS. 6 and 7, the configuration of the corresponding portions of
the intaglio would be such that it is tapering in the direction
toward the surface thereof. As a result, it would become very
difficult to release a cured barrier rib portion from the intaglio.
By the way, the configuration that can be easily released from the
intaglio is a reversed trapezoid.
[0070] (3) A problem which will be raised also in this method is
the entrapment of air bubbles. However, the aforementioned
publication is silent about this problem.
[0071] On the other hand, Jpn. Pat. Appln. KOKAI No. H10-101373
sets forth a very comprehensive and conceptual method, and the
method of the present invention is included in part in the method
of this Publication H10-101373. FIG. 8 shows a drawing which is
also shown in this Publication H10-101373.
[0072] This patent publication mentions that it includes not only a
rotary system but also a flat system, either of which however are
already disclosed in the aforementioned publications.
[0073] In conclusion, this publication simply sets forth a
gathering of known methods except that it discloses the employment
of a thermoplastic resin. Further, nothing is insisted in this
publication about any prominent effects to be obtained from a
specific combination of known methods.
[0074] Almost nothing is known about a specific embodiment of
apparatus which is useful for actually realizing these conventional
methods. Basic reasons for this may be ascribed to the problems
that some of them are excellent as an idea but are difficult to
actually realize, some of them fail to disclose a specific means
for securing the accuracy, and some of them are poor in
durability.
[0075] For example, as for the method of scraping out a redundant
portion of ink from the roll supplied with the ink, Jpn. Pat.
Appln. KOKAI No. H10-101373 proposes to employ a member called
doctor as shown in FIG. 8. However, when such a method is adopted
for removing a redundant portion of ink, the surface of intaglio
would be abraded and damaged with time unless the surface of the
roll is very hard and excellent in slip properties. Therefore, it
is required in a gravure printing to employ a metal roll having a
chrome-plated surface. The employment of a plastic roll is also
conceivable as an idea and may be advantageous in various aspects,
but is too poor in hardness, thus permitting it to be easily
abraded, so that a plastic roll is not actually employed.
[0076] Further, Jpn. Pat. Appln. KOKAI No. H10-101373 fails to
teach anything about the surface hardness and abrasion resistance
of the roll. However, according to examples thereof, a silicone
rubber type roll which is made of a room temperature curing
silicone (RTV141) is employed therein. However, since the rubber
hardness of RTV is 100 at most, the silicone rubber type roll seems
to be very questionable in terms of durability. On the other hand,
if the intaglio is very hard, it would be impossible to perform a
printing on a rigid substrate such as a glass substrate.
[0077] The present invention has been accomplished in view of the
aforementioned circumstances, and therefore, a first object of the
present invention is to provide a plasma display panel and a
manufacturing method thereof, which make it possible to easily
obtain a large image area of 40 inches or more, to realize an
increased fineness of discharge display cell, to obtain a stable
and accurate luminescence display, and to enhance the durability
thereof.
[0078] A second object of the present invention is to provide a
plasma display panel which is provided with barrier ribs which can
be hardly collapsed even if the width thereof is minimized, and
which makes it possible to minimize the leak of luminescence light
toward the rear side of the back substrate, to accurately set the
alignment between the electrodes and the barrier ribs, and to
prevent the generation of disconnection or short circuit of
electrodes.
[0079] A third object of the present invention is to provide a
plasma addressed liquid crystal display panel structure and a
manufacturing method thereof, which make it possible to erect
transparent barrier ribs perpendicular to a glass substrate, and to
produce the transparent barrier ribs having a smooth sidewalls.
[0080] A fourth object of the present invention is to provide a
method and an apparatus, which is suited for mass-production, and
which make it possible to form a thick projected pattern directly
onto a rigid substrate with excellent reproducibility by way of
intaglio-rotating system.
BRIEF SUMMARY OF THE INVENTION
[0081] According to a first embodiment of a first aspect of the
present invention, there is provided a plasma display panel
comprising:
[0082] a back substrate;
[0083] barrier ribs arranged on the back substrate;
[0084] electrodes each formed in a region partitioned by the
barrier ribs; and
[0085] a dielectric layer covering the electrodes;
[0086] wherein the barrier ribs and the dielectric layer comprise
the same barrier rib-forming material containing a low melting
point glass frit.
[0087] According to a second embodiment of the first aspect of the
present invention, there is provided a method of manufacturing a
plasma display panel, which comprises the steps of:
[0088] filling a barrier rib-forming paste containing glass frit in
a barrier ribs-forming intaglio;
[0089] superimposing a substrate on the barrier ribs-forming
intaglio filled with the barrier rib-forming paste containing glass
frit to thereby transfer the barrier rib-forming paste onto the
substrate; and
[0090] heating the barrier rib-forming paste which is transferred
to the substrate, thereby burning out existing organic components
and concurrently sintering the glass frit to thereby form the
barrier ribs and dielectric layer.
[0091] The followings are preferable embodiments of this first
aspect of the present invention.
[0092] (1) The film thickness of the dielectric layer is in the
range of 5 to 50 .mu.m.
[0093] (2) The film thickness of the dielectric layer is in the
range of 5 to 20 .mu.m.
[0094] (3) The dielectric layer has a two-layer structure
comprising a barrier rib material layer, and a low melting point
glass paste layer which differs in material from the barrier rib
material.
[0095] (4) The film thickness of the dielectric layer is in the
range of 5 to 20 .mu.m, and the dielectric layer has a two-layer
structure comprising a barrier rib material layer, and a low
melting point glass paste layer which differs in material from the
barrier rib material.
[0096] (5) A barrier rib-forming paste containing glass frit is
filled in a barrier ribs-forming intaglio, and a dielectric layer
having a predetermined thickness is concurrently formed on the
intaglio, the dielectric layer being subsequently transferred onto
the substrate.
[0097] According to a second aspect of the present invention, there
is provided a plasma display panel comprising:
[0098] a back substrate; and
[0099] barrier ribs arranged on the back substrate;
[0100] electrodes each formed in a region partitioned by the
barrier ribs;
[0101] wherein the barrier ribs have a recessed structure
comprising a bottom structure contacting with the back substrate,
and an upper structure projected from the bottom structure; and the
electrodes are each disposed at the bottom of the recessed
structure.
[0102] According to the second aspect of the present invention,
since the dielectric layer disposed at the bottom of discharge
display cell which is surrounded by the back substrate and the
barrier ribs formed integral with the back substrate can be
optimized in thickness thereof to thereby make it possible to
obtain the dielectric layer of uniform thickness, the quantity of
electric charge of the dielectric material constituting the
dielectric layer can be made uniform, thereby making it possible to
realize a stable and accurate luminescence display.
[0103] Further, since the dielectric material constituting the
dielectric layer is the same as the material constituting the
barrier ribs, and additionally, since the dielectric layer can be
formed concurrent with the formation of the barrier ribs, the
productivity can be enhanced and the manufacturing cost can be
saved in the manufacture of the substrate for plasma display.
[0104] The followings are preferable embodiments of this second
aspect of the present invention.
[0105] (1) The visible light reflectivity of the regions other than
the electrodes is 50% or more, more preferably 70% or more under
the condition where a phosphor is not coated.
[0106] (2) A recessed portion is formed at the bottom of the
opening portion of the recessed structure, and the electrode is
disposed at this recessed portion.
[0107] (3) The width of the recessed portion is the same in size as
the bottom of the opening portion of the recessed structure.
[0108] (4) The electrode is formed of a metal wire or a metal
plate.
[0109] (5) The thickness of the bottom of the recessed structure is
larger than the width of the upper structure of the recessed
portion.
[0110] (6) The thickness of the bottom of the recessed portion
which is formed at the bottom of the opening of the recessed
structure is larger than the width of the upper structure of the
recessed portion.
[0111] (7) A dielectric layer is formed at the bottom of the
recessed structure, and a total of the thickness of the bottom
structure of the recessed structure and the thickness of the
dielectric layer is larger than the width of the upper structure of
the recessed portion.
[0112] According to a first embodiment of a third aspect of the
present invention, there is provided a back plate of plasma
addressed liquid crystal display panel comprising:
[0113] a back substrate;
[0114] a transparent dielectric layer formed on the back
substrate;
[0115] transparent barrier ribs arranged on the transparent
dielectric layer and comprising the same material as that of the
transparent dielectric layer;
[0116] an anode formed on the transparent dielectric layer; and
[0117] a cathode formed on the transparent dielectric layer.
[0118] The followings are preferable examples of a first embodiment
according to the third aspect of the present invention.
[0119] (1) The film thickness of the transparent dielectric layer
is in the range of 3 to 15 .mu.m.
[0120] (2) The angle between the sidewall of the transparent
barrier rib and the back substrate is in the range of 85 to 95
degrees.
[0121] (3) The surface roughness of the sidewall of the transparent
barrier rib is within 1 .mu.m and is equivalent almost to an
optical flat surface.
[0122] (4) The anode and the cathode comprise the same
material.
[0123] (5) The anode and the cathode comprises a thick film or a
plated film, each containing 80% or more of Ni.
[0124] (6) The anode and the cathode comprises a thick film or a
vapor-deposited film, each containing 80% or more of Al.
[0125] (7) Among the anode and the cathode, at least cathode has a
two-layer structure.
[0126] (8) A back plate of the plasma addressed liquid crystal
display panel claimed in any one of claims 16 to 19.
[0127] (9) The anode and the cathode comprise the same material
having a photosensitivity, and employed respectively as an
underlying electrode, and at least the cathode is provided thereon
with a protective plating having a sputter resistance against the
cation of discharging gas and containing 80% or more of Ni.
[0128] (10) The underlying electrode is formed by using a
photosensitive Ag paste.
[0129] According to a second embodiment of the third aspect of the
present invention, there is provided a method of manufacturing a
back plate of plasma addressed liquid crystal display panel, which
comprises:
[0130] coating a barrier rib-forming paste containing glass frit on
a surface of substrate;
[0131] forming a pattern of barrier ribs by pressing the barrier
rib-forming paste formed on the surface of substrate by making use
of a barrier rib-forming intaglio;
[0132] heating the pattern of barrier ribs, thereby burning out
existing organic components and concurrently sintering the glass
frit to thereby form transparent barrier ribs and a transparent
dielectric layer; and
[0133] forming a cathode and an anode on the transparent dielectric
layer.
[0134] According to a third embodiment of the third aspect of the
present invention, there is provided a method of manufacturing a
back plate of plasma addressed liquid crystal display panel, which
comprises:
[0135] filling a barrier rib-forming paste containing glass frit in
a barrier ribs-forming intaglio, while concurrently enabling a
dielectric layer having a predetermined thickness to be formed on
the intaglio;
[0136] superimposing a substrate on the barrier ribs-forming
intaglio filled with the barrier rib-forming paste to thereby
transfer the barrier rib-forming paste onto the substrate to form a
pattern of barrier ribs;
[0137] heating the pattern of barrier ribs, thereby burning out
existing organic components and concurrently sintering the glass
frit to thereby form transparent barrier ribs and a transparent
dielectric layer; and
[0138] forming a cathode and an anode on the transparent dielectric
layer.
[0139] The followings are preferable examples of the second and
third embodiments according to the third aspect of the present
invention.
[0140] (1) The anode and the cathode are formed by means of an
electroless plating method.
[0141] (2) The anode and the cathode are formed by a procedure
comprising: coating a thick film paste; coating a liquid
photoresist; patterning the photoresist; forming an electrode
pattern by means of sand blast; and sintering the electrode
pattern.
[0142] (3) The anode and the cathode are formed by means of a
photosensitive paste method.
[0143] (4) The anode and the cathode are formed by means of a vapor
deposition method.
[0144] (5) Among the anode and the cathode, at least the cathode
has a two-layer structure, and an underlying electrode of the
two-layer structure is formed through an electrolytic plating using
a material having a sputter resistance against plasma cation.
[0145] According to a first embodiment of the fourth aspect of the
present invention, there is provided a recessed and projected
pattern-forming apparatus of rotary type for forming a cured
recessed and projected pattern of an ionizing radiation-curable
resin composition on a rigid plate, the apparatus comprising:
[0146] an intaglio-rotating roll provided on the surface thereof
with a predetermined recessed and projected pattern constituted by
a releasable surface;
[0147] a pinching mechanism for enabling the ionizing
radiation-curable resin composition to be continuously pinched
between the intaglio-rotating roll and an ionizing
radiation-permeable releasable film while keeping a predetermined
thickness of the ionizing radiation-curable resin composition;
[0148] an radiation irradiating mechanism for irradiating an
ionizing radiation to the resin composition under the
aforementioned pinched condition;
[0149] a releasing mechanism for releasing the ionizing
radiation-permeable releasable film from the surface of the
intaglio-rotating roll after finishing the curing of the ionizing
radiation-curable resin composition;
[0150] a press mechanism which is designed such that the rigid
plate is fed over the intaglio-rotating roll for enabling the rigid
plate to be superimposed and aligned, at a predetermined precision,
with the ionizing radiation-curable resin composition which is
cured by the ionizing radiation, and that the resultant composition
thus aligned is placed into a compressed state; and
[0151] a releasing mechanism for enabling the rigid plate to be
released from the surface of the intaglio-rotating roll after a
termination of the compressed state.
[0152] According to a second embodiment of the fourth aspect of the
present invention, there is provided a rotary type recessed and
projected pattern-forming method for forming a cured recessed and
projected pattern of an ionizing radiation-curable resin
composition on a rigid plate, the method comprising:
[0153] continuously permitting the ionizing radiation-curable resin
composition to be pinched between an intaglio-rotating roll and an
ionizing radiation-permeable releasable film while keeping a
predetermined thickness of the ionizing radiation-curable resin
composition, the intaglio-rotating roll being provided on the
surface thereof with a predetermined recessed and projected pattern
constituted by a releasable surface;
[0154] irradiating an ionizing radiation onto the resin composition
under the aforementioned pinched condition;
[0155] releasing the ionizing radiation-permeable releasable film
from the surface of the intaglio-rotating roll after finishing the
curing of the ionizing radiation-curable resin composition;
[0156] feeding the rigid plate over the intaglio-rotating roll for
enabling the rigid plate to be superimposed and aligned, at a
predetermined precision, with the ionizing radiation-curable resin
composition which is cured by the ionizing radiation, and placing
the resultant composition thus aligned into a compressed state;
and
[0157] releasing the rigid plate from the surface of the
intaglio-rotating roll after a termination of the compressed
state.
[0158] The followings are preferable examples of the first and
second embodiments according to the fourth aspect of the present
invention.
[0159] (1) The surface of the intaglio-rotating roll comprises
silicone resin.
[0160] (2) These embodiments further comprises a mechanism or step
of preliminarily coating a self-adhesive or an adhesive onto the
rigid plate to be fed over the intaglio-rotating roll.
[0161] (3) These embodiments further comprises a mechanism or step
of coating a transferring resin onto the surface of the cured
ionizing radiation-curable. resin composition.
[0162] (4) The width of the ionizing radiation-permeable releasable
film having a releasability is larger than the width of the
intaglio-rotating roll.
[0163] (5) The mechanism or step of continuously permitting the
ionizing radiation-curable resin composition to be pinched between
an intaglio-rotating roll and an ionizing radiation-permeable
releasable film while keeping a predetermined thickness of the
ionizing radiation-curable resin composition is constituted by a
mechanism or step wherein the ionizing radiation-curable resin
composition is coated in advance on the surface of the ionizing
radiation-permeable releasable film, and then, the film is
superimposed with the intaglio-rotating roll.
[0164] (6) These embodiments further comprises a mechanism or step
of preliminarily coating a self-adhesive or an adhesive onto the
surface of the ionizing radiation-permeable releasable film.
[0165] (7) These embodiments further comprises a mechanism or step
of feeding a liquid to a region where the intaglio-rotating roll
begins to be in contact with the ionizing radiation-curable resin
composition.
[0166] (8) These embodiments further comprises a mechanism or step
of feeding a liquid to a region where the intaglio-rotating roll
begins to be in contact with the rigid plate.
[0167] (9) The mechanism of transferring the rigid plate is
constituted by an X-Y-.theta. table having a mechanism of securing
the rigid plate and designed to be moved following a guide
rail.
[0168] (10) An alignment mark is attached to both of the
intaglio-rotating roll and the rigid plate at their corresponding
positions, thereby making it possible to transfer the alignment
mark of-the intaglio to the rigid plate, and to measure any
misregistration between the alignment mark of the intaglio which is
transferred to the rigid plate and the alignment mark of the rigid
plate, thereby enabling the position of the X-Y-.theta. table
holding the rigid plate to be adjusted correspondingly so as to
perform the alignment between the intaglio and the rigid plate.
[0169] Additional objects and advantages of the invention will be
set forth in the description which follows, and in part will be
obvious from the description, or may be learned by practice of the
invention. The objects and advantages of the invention may be
realized and obtained by means of the instrumentalities and
combinations particularly pointed out hereinafter.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0170] The accompanying drawings, which are incorporated in and
constitute a part of the specification, illustrate embodiments of
the invention, and together with the general description given
above and the detailed description of the embodiments given below,
serve to explain the principles of the invention.
[0171] FIG. 1 is a cross-sectional view showing the back plate of
ordinary plasma display substrate;
[0172] FIG. 2 is a perspective view illustrating the structure of
plasma addressed liquid crystal display panel;
[0173] FIG. 3 is a cross-sectional view illustrating the structure
of plasma addressed liquid crystal display panel;
[0174] FIG. 4 is a block diagram for illustrating the manufacturing
steps of the back plate of the conventional plasma addressed liquid
crystal display panel;
[0175] FIGS. 5 to 7 illustrate the conventional method of forming
the barrier ribs and the configuration of the barrier ribs of the
conventional plasma addressed liquid crystal display panel;
[0176] FIG. 8 is a schematical view illustrating the conventional
method of forming the barrier ribs of the plasma addressed liquid
crystal display panel;
[0177] FIG. 9 is a drawing illustrating one example of the barrier
rib-forming intaglio which is adapted to be employed in a first
aspect of the present invention;
[0178] FIG. 10 is a drawing illustrating a state wherein a barrier
rib-forming material is filled in the barrier rib-forming intaglio
which is adapted to be employed in a first aspect of the present
invention;
[0179] FIG. 11 is a drawing illustrating a state of alignment
between a glass substrate bearing thereon an electrode pattern and
the barrier rib-forming intaglio filled with a barrier rib-forming
material in a first aspect of the present invention;
[0180] FIG. 12 is a drawing illustrating a transferring step where
an adhesive or a self-adhesive is employed in a first aspect of the
present invention;
[0181] FIG. 13 is a drawing illustrating a state where a dielectric
layer of two-layer structure is formed on the surface of substrate
in a first aspect of the present invention;
[0182] FIG. 14 is a drawing illustrating a state where a dielectric
layer of two-layer structure is formed on the surface of intaglio
in a first aspect of the present invention;
[0183] FIG. 15 is a drawing illustrating a state wherein the
barrier rib-forming intaglio to be employed in a first aspect of
the present invention is peeled away;
[0184] FIG. 16 is a drawing showing a back plate after the
sintering thereof according to a first aspect of the present
invention;
[0185] FIG. 17 is a cross-sectional view of the back plate of
plasma display substrate according to a second aspect of the
present invention;
[0186] FIG. 18 is a cross-sectional view illustrating another
example of the back plate of plasma display substrate according to
a second aspect of the present invention;
[0187] FIG. 19 is a cross-sectional view illustrating another
example of the back plate of plasma display substrate according to
a second aspect of the present invention;
[0188] FIG. 20 is a cross-sectional view illustrating another
example of the back plate of plasma display substrate according to
a second aspect of the present invention;
[0189] FIG. 21 is a cross-sectional view illustrating another
example of the back plate of plasma display substrate according to
a second aspect of the present invention;
[0190] FIG. 22 is a cross-sectional view illustrating another
example of the back plate of plasma display substrate according to
a second aspect of the present invention;
[0191] FIG. 23 is a cross-sectional view illustrating another
example of the back plate of plasma display substrate according to
a second aspect of the present invention;
[0192] FIG. 24 is a cross-sectional view illustrating another
example of the back plate of plasma display substrate according to
a second aspect of the present invention;
[0193] FIG. 25 is a cross-sectional view illustrating another
example of the back plate of plasma display substrate according to
a second aspect of the present invention;
[0194] FIG. 26 is a drawing illustrating the structure of the
plasma addressed liquid crystal display panel according to a third
aspect of the present invention;
[0195] FIG. 27 is a drawing illustrating the structure of another
example of the plasma addressed liquid crystal display panel
according to a third aspect of the present invention;
[0196] FIG. 28 is a drawing illustrating the step of manufacturing
the transparent barrier ribs and dielectric layers according to a
third aspect of the present invention;
[0197] FIG. 29 is a drawing illustrating the step of manufacturing
the electrodes according to a third aspect of the present
invention;
[0198] FIG. 30 is a drawing illustrating another manufacturing
process of the transparent barrier ribs and dielectric layers
according to a third aspect of the present invention;
[0199] FIG. 31 is a drawing illustrating another manufacturing
process of the electrodes according to a third aspect of the
present invention; and
[0200] FIG. 32 is a drawing illustrating a recessed and projected
pattern-forming apparatus according to a fourth aspect of the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0201] Various embodiments of the present invention will be
explained in details with reference to the drawings as follows.
[0202] First of all, the dielectric layer of plasma display panel
substrate and the manufacturing method thereof according to a first
aspect of the present invention will be explained.
[0203] As shown in FIG. 9, barrier rib-forming intaglio 101
corresponds to a reversed configuration of barrier ribs. As for the
barrier rib-forming intaglio 101, a metal intaglio or a resin
intaglio can be employed, and the configuration thereof may be of a
cylindrical plate or a flattened plate.
[0204] As a typical example of the metal intaglio, a copper plate
engraved or etched, i.e. such as those employed in the intaglio
printing can be employed. As for the resin intaglio, it can be
manufactured by a method where a resin is filled in a metallic
letterpress constituting a matrix of intaglio, and then, the copy
thereof is taken up as an intaglio, or by a method where a
photosensitive resin is cured through a photomask, and the
resultant cured resin is subjected to a development process to
thereby form an intaglio.
[0205] As shown in FIG. 10, barrier rib-forming material 102 is
filled in the barrier rib-forming intaglio 101 to thereby allowing
dielectric layer 103 to be produced concurrently. More
specifically, barrier rib-forming material 102 is filled in the
groove of barrier rib-forming intaglio 101, and at the same time, a
layer having an uniform thickness is allowed to be formed on the
intaglio. As a result, the dielectric layer 103 can be formed on
the top of the barrier rib-forming intaglio 101.
[0206] By making use of the aforementioned method, it becomes
possible to overcome various problems which may be raised on the
occasion of filling the paste in the intaglio, i.e. to prevent the
paste filled in the intaglio from being taken out by a doctor
blade, to prevent the entrapment of air bubble in the paste, or to
prevent the paste from being left in the intaglio.
[0207] Further, if the thickness of the dielectric layer 103 is too
thin, the electrodes may be exposed, thereby making the dielectric
layer 103 ineffective. On the other hand, if the thickness of the
dielectric layer 103 is too thick, it will invite the generation of
splits or cracks on the occasion of sintering the substrate.
[0208] The barrier ribs 107 and dielectric layer 103 should
preferably be white in color and excellent in reflectance so as to
enable the luminescence of phosphor to be reflected to thereby
improve the brightness. Therefore, a white pigment such as
TiO.sub.2, ZrO.sub.2, Al.sub.2O.sub.3, etc. can be added to the
barrier rib-forming material 102. In this case, the ratio of a
white pigment to a low melting point glass is generally in the
range of 3 to 30% in view of maintaining the configuration of the
barrier ribs 107 in the sintering step as well as in view of
density of the barrier ribs 107.
[0209] If it is desired to employ the barrier rib-forming material
102 as a protective layer 103 of electrode, the thickness of the
dielectric layer 103 is required to be 5 .mu.m or more in order to
obtain a sufficient reflectance. On the other hand, if the
thickness of the dielectric layer 103 is 50 .mu.m or more, it will
invite an increase of address voltage or it may become difficult to
perform accurate address, and hence it is undesirable.
[0210] Due to these reasons, the thickness of the dielectric layer
103 should preferably be in the range of 5 to 50 .mu.m. However,
particularly in view of lowering the address voltage so as to
decrease the driving voltage of driving circuit as low as possible
and to reduce the cost of dielectric material, the thickness of the
dielectric layer 103 should preferably be 20 .mu.m or less.
[0211] As for the barrier rib-forming material 102 to be charged
into the barrier rib-forming intaglio 101, the employment of a
paste having an excellent fluidity is preferable for the purpose of
filling the intaglio. As for the type of curing, it may be selected
from an evaporation curing type, a heat curing type, a two-part
curing type, and an ionizing radiation curing type such as
ultraviolet rays, electron beam, X-rays, etc. Therefore, the
barrier rib-forming material comprises an inorganic powder which is
capable of sintering through sintering, and an organic component
for giving a fluidity to the paste and for retaining the
configuration of barrier rib after the curing thereof.
[0212] As for the inorganic component, it is possible to employ the
powder of a low melting point glass represented by
PbO-B.sub.2O.sub.3-SiO.sub.2, to which a white pigment such as
Al.sub.2O.sub.3, TiO.sub.2, ZrO.sub.2, etc. may be added. However,
for the purpose of adjusting the color tone of the barrier ribs,
any desired pigments may be added to the glass powder.
[0213] As for the organic component, though it may differ depending
on the cured state, a material which is capable of removing a
binder therefrom at a temperature of not higher than the glass
softening temperature thereof is preferable. In the case of the
evaporation curing type for example, a solution of resin wherein a
general-purpose natural resin, a semi-synthetic resin or a
synthetic resin is dissolved in a solvent can be employed. In the
cases of the heat curable type, the two-part curing type and the
ionizing radiation curing type, a cured state of paste can be
achieved by combining a reactive resin or a reactive monomer with a
polymerization initiator. Two of more kinds of these cured types
can be combined together.
[0214] After the barrier rib-forming material 102 is filled in the
barrier rib-forming intaglio 101, the positioning of the glass
substrate 104 having an electrode pattern 105 deposited thereon in
advance is performed as shown in FIG. 11, and then, the barrier
rib-forming material 102 is transferred to the surface of the glass
substrate 104. In this case, any of the following methods can be
selected, i.e. a method wherein the barrier rib-forming material
102 is allowed to cure before the barrier rib-forming material 102
is transferred onto the glass substrate 104; and a method wherein
the barrier rib-forming material 102 is allowed to contact with the
glass substrate 104 before the barrier rib-forming material 102 is
still in an uncured state, and under this condition, the barrier
rib-forming material 102 is allowed to cure. Although any of these
methods can be selected, it is more preferable to cure the barrier
rib material before it is transferred to the glass substrate in
order to prevent the generation of transfer residue of the barrier
rib material in the intaglio.
[0215] In the case of the former transfer method, an adhesive or a
self-adhesive 106 is required to be interposed between the barrier
rib-forming material 102 and the glass substrate 104 as shown in
FIG. 12. In the case of the latter transfer method however, since
the barrier rib-forming material 102 is allowed to cure on the
glass substrate 104, the adhesive or the self-adhesive 106 is no
longer required to be employed. However, the adhesive or the
self-adhesive 106 may be employed for the purpose of enhancing the
mechanical strength of the barrier ribs.
[0216] By the way, as shown in FIG. 13, a dielectric layer
comprising a low melting point glass paste which differs from the
barrier rib-forming material may be formed over the electrode
pattern formed in advance on the back plate. Further, as shown in
FIG. 14, the barrier rib-forming material is filled in the recessed
portions of the barrier rib-forming intaglio 101 so as to enable
the dielectric layer to be formed concurrently, and then, a
dielectric layer 108 comprising a low melting point glass paste
which differs from the barrier rib-forming material may be formed
over the barrier rib-forming material filled in the recessed
portions. In this case however, the dielectric layer becomes a
two-layer structure consisting of the dielectric layer 103 that has
been formed concurrent with the barrier ribs using a barrier
rib-forming material, and the dielectric layer 108 comprising a low
melting point glass paste which differs from the barrier
rib-forming material.
[0217] Depending on the thickness of the dielectric layer and also
on the barrier rib-forming material, splitting or cracks may be
generated:on the occasion of sintering the dielectric layer and the
barrier ribs due to the recess and projection of the electrode
pattern formed on the glass substrate. If the generation of these
splitting or cracks is to be prevented, it would be effective to
form a dielectric layer comprising a low melting point glass paste
which differs from the barrier rib-forming material on the
electrode pattern that has been formed on a glass substrate. It is
possible, with the provision of this dielectric layer, to absorb
the recess and projection of the electrode pattern and hence to
flatten the surface, thereby making it possible to prevent the
generation of these splitting or cracks.
[0218] As for the low melting point glass paste, it is preferable
to employ those which are consisting only of low melting point
glass frit comprising no inorganic aggregate. However, a dielectric
paste available in the market can be also employed as long as the
softening point thereof is lower than that of the barrier
rib-forming material.
[0219] Thereafter, as shown in FIG. 15, the glass substrate 104
transferred to the barrier ribs 107 is baked to vanish organic
components and to sinter the glass components. As a result, the
back plate of plasma display panel, which is provided with
inorganic barrier ribs 107 and the dielectric layer 103 can be
obtained as shown in FIG. 16.
[0220] As explained above, according to the first aspect of the
present invention, the back plate of plasma display panel can be
manufactured by making use of a method wherein the dielectric Layer
103 and the barrier ribs 107 are both formed of the same
material.
[0221] Next, specific examples of the first aspect of the present
invention will be explained. By the way, it should be noted that
the following examples are not intended to limit the scope of the
present invention.
EXAMPLE 1
[0222] The barrier rib-forming intaglio employed herein has the
following features.
[0223] The type of intaglio: Flat type resin intaglio made of
polyethylene;
[0224] The configuration of grooves: Stripe-shaped, 30 .mu.m in
width, 200 .mu.m in depth and 140 .mu.m in pitch.
[0225] The barrier rib-forming material was obtained by fully
kneading the following composition by making use of a roll
mill.
1 PbO--B.sub.2O.sub.3--SiO.sub.2 type low melting point glass 62
parts by weight powder: Al.sub.2O.sub.3: 12 parts by weight
TiO.sub.2: 8 parts by weight Diethylene glycol dimethacrylate 10
parts by weight 2-hydroxyproply acrylate 7 parts by weight
Benzophenone 1 part by weight
[0226] The barrier rib-forming material thus obtained was filled,
by means of roll press, in a polystyrene flat intaglio having
recessed portions, i.e. reversed in configuration of the barrier
ribs, thereby simultaneously forming the portion of barrier ribs
and the portion of dielectric layer. Then, ultra-violet rays were
irradiated onto this barrier rib-forming material under the
condition of 2000 mJ/cm.sup.2.
[0227] Then, the intaglio filled with the barrier rib-forming
material was placed on and aligned with a glass substrate coated,
all over the surface thereof, with acrylic self-adhesive 5 .mu.m in
thickness, and then, a flat press was performed onto the resultant
composite body with a pressure of 5 Kgf/cm.sup.2.
[0228] Thereafter, the intaglio was released from the substrate and
baked for 30 minutes at a temperature of 580.degree. C. to thereby
obtain a back plate provided with a dielectric layer having a
uniform thickness of 10 .mu.m.
EXAMPLE 2
[0229] The barrier rib-forming intaglio employed herein has the
following features.
[0230] The type of intaglio: Flat type resin intaglio made of
silicone rubber;
[0231] The configuration of grooves: Stripe-shaped, 30 .mu.m in
width, 200 .mu.m in depth and 140 .mu.m in pitch.
[0232] The barrier rib-forming material was obtained by fully
kneading the following composition by making use of a roll
mill.
2 PbO--B.sub.2O.sub.3--SiO.sub.2 type low melting point glass 62
parts by weight powder: Al.sub.2O.sub.3: 12 parts by weight
TiO.sub.2: 8 parts by weight Diethylene glycol dimethacrylate 10
parts by weight 2-hydroxyproply acrylate 7 parts by weight
Benzophenone 1 part by weight
[0233] The barrier rib-forming material thus obtained was filled,
by means of doctor blade, in a silicone rubber flat intaglio having
recessed portions, i.e. reversed in configuration of the barrier
ribs, thereby simultaneously forming the portion of barrier ribs
and the portion of dielectric layer. Then, ultra-violet rays were
irradiated onto this barrier rib-forming material under the
condition of 2000 mJ/cm.sup.2.
[0234] Then, the intaglio filled with the barrier rib-forming
material was placed on and aligned with a glass substrate coated,
all over the surface thereof, with acrylic self-adhesive 5 .mu.m in
thickness, and then, a flat press was performed onto the resultant
composite body with a pressure of 5 Kgf/cm.sup.2.
[0235] Thereafter, the intaglio was released from the substrate and
baked for 30 minutes at a temperature of 580.degree. C. to thereby
obtain a back plate provided with a dielectric layer having a
uniform thickness of 10 .mu.m.
EXAMPLE 3
[0236] The barrier rib-forming intaglio employed herein has the
following features.
[0237] The type of intaglio: Flat type resin intaglio made of
silicone rubber;
[0238] The configuration of grooves: Stripe-shaped, 50 .mu.m in
width, 150 .mu.m in depth and 150 .mu.m in pitch.
[0239] The barrier rib-forming material was obtained by fully
kneading the following composition by making use of a roll
mill.
3 PbO--B.sub.2O.sub.3--SiO.sub.2 type low melting point glass 62
parts by weight powder: Al.sub.2O.sub.3: 12 parts by weight
TiO.sub.2: 8 parts by weight Diethylene glycol dimethacrylate: 10
parts by weight 2-hydroxyproply acrylate: 7 parts by weight
Benzophenone: 1 part by weight
[0240] The barrier rib-forming material thus obtained was filled,
by means of doctor blade, in a polystyrene flat intaglio having
recessed portions, i.e. reversed in configuration of the barrier
ribs, thereby simultaneously forming the portion of barrier ribs
and the portion of dielectric layer. Then, ultra-violet rays were
irradiated onto this barrier rib-forming material under the
condition of 2000 mJ/cm.sup.2.
[0241] Then, the intaglio filled with the barrier rib-forming
material was placed on and aligned with a glass substrate coated,
all over the surface thereof, with acrylic self-adhesive 5 .mu.m in
thickness, and then, a flat press was performed onto the resultant
composite body with a pressure of 5 Kgf/cm.sup.2.
[0242] Thereafter, the intaglio was released from the substrate and
baked for 30 minutes at a temperature of 580.degree. C. to thereby
obtain a back plate provided with a dielectric layer having a
uniform thickness of 5 .mu.m.
EXAMPLE 4
[0243] The barrier rib-forming intaglio employed herein has the
following features.
[0244] The type of intaglio: Flat type resin intaglio made of
polystyrene;
[0245] The configuration of grooves: Stripe-shaped, 50 .mu.m in
width, 150 .mu.m in depth and 150 .mu.m in pitch.
[0246] The barrier rib-forming material was obtained by fully
kneading the following composition by making use of a roll
mill.
4 PbO--B.sub.2O.sub.3--SiO.sub.2 type low melting point glass 62
parts by weight powder: Al.sub.2O.sub.3: 12 parts by weight
TiO.sub.2: 8 parts by weight Diethylene glycol dimethacrylate: 10
parts by weight 2-hydroxyproply acrylate: 7 parts by weight
Benzophenone: 1 part by weight
[0247] The barrier rib-forming material thus obtained was filled,
by means of screen printing, in a polystyrene flat intaglio having
recessed portions, i.e. reversed in configuration of the barrier
ribs, thereby simultaneously forming the portion of barrier ribs
and the portion of dielectric layer. Then, ultra-violet rays were
irradiated onto this barrier rib-forming material under the
condition of 2000 mJ/cm.sup.2.
[0248] Then, the intaglio filled with the barrier rib-forming
material was placed on and aligned with a glass substrate coated,
all over the surface thereof, with acrylic self-adhesive 5 .mu.m in
thickness, and then, a flat press was performed onto the resultant
composite body with a pressure of 5 Kgf/cm.sup.2.
[0249] Thereafter, the intaglio was released from the substrate and
baked for 30 minutes at a temperature of 580.degree. C. to thereby
obtain a back plate provided with a dielectric layer having a
uniform thickness of 20 .mu.m. By the way, when a panel
manufactured using this back plate was driven, the address voltage
was 50V and the address discharge-initiating voltage was 230V.
EXAMPLE 5
[0250] The barrier rib-forming intaglio employed herein has the
following features.
[0251] The type of intaglio: Flat type resin intaglio made of
polystyrene;
[0252] The configuration of grooves: Stripe-shaped, 50 .mu.m in
width, 150 .mu.m in depth and 150 .mu.m in pitch.
[0253] The barrier rib-forming material was obtained by fully
kneading the following composition by making use of a roll
mill.
5 PbO--B.sub.2O.sub.3--SiO.sub.2 type low melting point glass 62
parts by weight powder: Al.sub.2O.sub.3: 12 parts by weight
TiO.sub.2: 8 parts by weight Diethylene glycol dimethacrylate: 10
parts by weight 2-hydroxyproply acrylate: 7 parts by weight
Benzophenone: 1 part by weight
[0254] The barrier rib-forming material thus obtained was filled,
by means of screen printing, in a polystyrene flat intaglio having
recessed portions, i.e. reversed in configuration of the barrier
ribs, thereby simultaneously forming the portion of barrier ribs
and the portion of dielectric layer. Then, ultra-violet rays were
irradiated onto this barrier rib-forming material under the
condition of 2000 mJ/cm.sup.2.
[0255] Then, the intaglio filled with the barrier rib-forming
material was placed on and aligned with a glass substrate coated,
all over the surface thereof, with acrylic self-adhesive 5 .mu.m in
thickness, and then, a flat press was performed onto the resultant
composite body with a pressure of 5 Kgf/cm.sup.2.
[0256] Thereafter, the intaglio was released from the substrate and
baked for 30 minutes at a temperature of 580.degree. C. to thereby
obtain a back plate provided with a dielectric layer having a
uniform thickness of 40 .mu.m. By the way, when a panel
manufactured using this back plate was driven, the address voltage
was 60V and the address discharge-initiating voltage was 250V.
EXAMPLE 6
[0257] The barrier rib-forming intaglio employed herein has the
following features.
[0258] The type of intaglio: Flat type resin intaglio made of
silicone rubber;
[0259] The configuration of grooves: Stripe-shaped, 70 .mu.m in
width, 175 .mu.m in depth and 360 .mu.m in pitch.
[0260] The barrier rib-forming material was obtained by fully
kneading the following composition by making use of a roll
mill.
6 PbO--B.sub.2O.sub.3--SiO.sub.2 type low melting point glass 62
parts by weight powder: Al.sub.2O.sub.3: 12 parts by weight
TiO.sub.2: 8 parts by weight Diethylene glycol dimethacrylate: 10
parts by weight 2-hydroxyproply acrylate 7 parts by weight
Benzophenone 1 part by weight
[0261] A mixture consisting of the following composition was fully
kneaded by making use of a roll mill to obtain a dielectric
layer-forming material differing in composition from that of the
barrier rib-forming material.
7 PbO--B.sub.2O.sub.3--SiO.sub.2 type low melting point glass 60
parts by weight powder: Ethyl cellulose: 15 parts by weight
Butylcarbitol acetate: 25 parts by weight
[0262] The barrier rib-forming material thus obtained was filled,
by means of screen printing, in a silicone rubber flat intaglio
having recessed portions, i.e. reversed in configuration of the
barrier ribs, thereby simultaneously forming the portion of barrier
ribs and the portion of dielectric layer. Then, ultra-violet rays
were irradiated onto this barrier rib-forming material under the
condition of 2000 mJ/cm.sup.2.
[0263] An electrode pattern was formed at first on the surface of
glass substrate, and then, a dielectric layer consisting of a low
melting point glass paste differing in composition from that of the
barrier rib-forming material was deposited to a thickness of 5
.mu.m by means of screen printing. Thereafter, an acrylic
self-adhesive was coated all over the glass substrate to a
thickness of 5 .mu.m. Then, the intaglio filled with the barrier
rib-forming material was placed on and aligned with the glass
substrate, and a flat press was performed onto the resultant
composite body with a pressure of 5 Kgf/cm.sup.2.
[0264] Thereafter, the intaglio was released from the substrate and
baked for 30 minutes at a temperature of 580.degree. C. to thereby
obtain a back plate provided with a dielectric layer having a
uniform thickness of 10 .mu.m.
EXAMPLE 7
[0265] The barrier rib-forming intaglio employed herein has the
following features.
[0266] The type of intaglio: Flat type resin intaglio made of
silicone rubber;
[0267] The configuration of grooves: Stripe-shaped, 70 .mu.m in
width, 175 .mu.m in depth and 360 .mu.m in pitch.
[0268] The barrier rib-forming material was obtained by fully
kneading the following composition by making use of a roll
mill.
8 PbO--B.sub.2O.sub.3--SiO.sub.2 type low melting point glass 62
parts by weight powder: Al.sub.2O.sub.3: 12 parts by weight
TiO.sub.2: 8 parts by weight Diethylene glycol dimethacrylate: 10
parts by weight 2-hydroxyproply acrylate 7 parts by weight
Benzophenone 1 part by weight
[0269] A mixture consisting of the following composition was fully
kneaded by making use of a roll mill to obtain a dielectric
layer-forming material differing in composition from that of the
barrier rib-forming material.
9 PbO--B.sub.2O.sub.3--SiO.sub.2 type low melting point glass 60
parts by weight powder: Ethyl cellulose: 15 parts by weight
Butylcarbitol acetate: 25 parts by weight
[0270] The barrier rib-forming material thus obtained was filled,
by means of screen printing, in a silicone rubber flat intaglio
having recessed portions, i.e. reversed in configuration of the
barrier ribs, thereby simultaneously forming the portion of barrier
ribs and the portion of dielectric layer. Then, ultra-violet rays
were irradiated onto this barrier rib-forming material under the
condition of 2000 mJ/cm.sup.2.
[0271] Then, a dielectric layer-forming material having a different
composition from that of the barrier rib-forming material was
deposited to a thickness of 5 .mu.m by means of screen printing on
the surface of intaglio having barrier ribs and dielectric layer
formed thereon. Thereafter, an acrylic self-adhesive was coated all
over the glass substrate provided in advance with an electrode
pattern to thereby form an acrylic self-adhesive layer having a
thickness of 5 .mu.m. Then, the intaglio filled with the barrier
rib-forming material was placed on and aligned with the glass
substrate, and a flat press was performed onto the resultant
composite body with a pressure of 5 Kgf/cm.sup.2.
[0272] Thereafter, the intaglio was released from the substrate and
baked for 30 minutes at a temperature of 580.degree. C. to thereby
obtain a back plate provided with a dielectric layer having a
uniform thickness of 10 .mu.m.
COMPARATIVE EXAMPLE 1
[0273] The barrier rib-forming intaglio employed herein has the
following features.
[0274] The type of intaglio: Flat type resin intaglio made of
polystyrene;
[0275] The configuration of grooves: Stripe-shaped, 50 .mu.m in
width, 150 .mu.m in depth and 150 .mu.m in pitch.
[0276] The barrier rib-forming material was obtained by fully
kneading the following composition by making use of a roll
mill.
10 PbO--B.sub.2O.sub.3--SiO.sub.2 type low melting point glass 62
parts by weight powder: Al.sub.2O.sub.3: 12 parts by weight
TiO.sub.2: 8 parts by weight Diethylene glycol dimethacrylate: 10
parts by weight 2-hydroxyproply acrylate: 7 parts by weight
Benzophenone: 1 part by weight
[0277] The barrier rib-forming material thus obtained was filled,
by means of screen printing, in a polystyrene flat intaglio having
recessed portions, i.e. reversed in configuration of the barrier
ribs, thereby simultaneously forming the portion of barrier ribs
and the portion of dielectric layer. Then, ultra-violet rays were
irradiated onto this barrier rib-forming material under the
condition of 2000 mJ/cm.sup.2.
[0278] Then, the intaglio filled with the barrier rib-forming
material was placed on and aligned with a glass substrate coated,
all over the surface thereof, with acrylic self-adhesive 5 .mu.m in
thickness, and then, a flat press was performed onto the resultant
composite body with a pressure of 5 Kgf/cm.sup.2.
[0279] Thereafter, the intaglio was released from the substrate and
baked for 30 minutes at a temperature of 580.degree. C. to thereby
obtain a back plate provided with a dielectric layer having a
uniform thickness of 60 .mu.m. However, a large number of splits or
cracks were recognized at the barrier ribs and the dielectric layer
on the occasion of sintering, thus failing to obtain a
non-defective back plate.
COMPARATIVE EXAMPLE 2
[0280] The barrier rib-forming intaglio employed herein has the
following features.
[0281] The type of intaglio: Flat type resin intaglio made of
polystyrene;
[0282] The configuration of grooves: Stripe-shaped, 50 .mu.m in
width, 150 .mu.m in depth and 150 .mu.m in pitch.
[0283] The barrier rib-forming material was obtained by fully
kneading the following composition by making use of a roll
mill.
11 PbO--B.sub.2O.sub.3--SiO.sub.2 type low melting point glass 62
parts by weight powder: Al.sub.2O.sub.3: 12 parts by weight
TiO.sub.2: 8 parts by weight Diethylene glycol dimethacrylate: 10
parts by weight 2-hydroxyproply acrylate: 7 parts by weight
Benzophenone: 1 part by weight
[0284] The barrier rib-forming material thus obtained was filled,
by means of screen printing, in a polystyrene flat intaglio having
recessed portions, i.e. reversed in configuration of the barrier
ribs, thereby simultaneously forming the portion of barrier ribs
and the portion of dielectric layer. Then, ultra-violet rays were
irradiated onto this barrier rib-forming material under the
condition of 2000 mJ/cm.sup.2.
[0285] Then, the intaglio filled with the barrier rib-forming
material was placed on and aligned with a glass substrate coated,
all over the surface thereof, with acrylic self-adhesive 5 .mu.m in
thickness, and then, a flat press was performed onto the resultant
composite body with a pressure of 5 Kgf/cm.sup.2.
[0286] Thereafter, the intaglio was released from the substrate and
baked for 30 minutes at a temperature of 580.degree. C. to thereby
obtain a back plate provided with a dielectric layer having a
uniform thickness of 2 .mu.m. However, part of the dielectric layer
was left unfilled with the barrier rib-forming material on the
occasion of filling the barrier rib-forming material in the
intaglio by making use of a doctor blade, thus allowing part of
electrodes to expose.
[0287] As explained above, according to the method of forming the
barrier ribs and dielectric layer of the plasma display panel in
the first aspect of the present invention, since the dielectric
layer can be formed concurrent with the formation of the barrier
ribs by making use of the same material, it becomes possible to
provide the back plate of plasma display panel using a simple
manufacturing process, and at the same time, the raw material cost
thereof can be reduced.
[0288] Next, a second aspect of the present invention will be
explained with reference to drawings. By the way, although only
three rows of barrier ribs are shown in the drawings, the substrate
will be actually constituted by a predetermined number of rows of
barrier rib as required by the specification of the plasma display
panel.
[0289] In this second aspect of the present invention, the barrier
ribs are formed not individually in a form of column, but are
formed integrally with their bottom portions being made common to
each other, i.e. the barrier ribs are constituted by an assembly of
U-shaped structures.
[0290] Specifically, many a number of barrier ribs 202 each having
a U-shaped configuration are formed on a glass substrate 201, and
an electrode 203 is disposed inside this recessed portion of the
barrier rib 202. Further, this electrode 203 in the recessed
portion is covered with a dielectric layer 204.
[0291] According to this structure of barrier ribs 202, since the
bottoms thereof are made common to each other, the barrier ribs 202
can be hardly collapsed even if the width of barrier rib is
minimized. Further, since the electrode is disposed inside this
recessed portion of the barrier rib 202, the electrode 203 can be
formed after the fabrication of the barrier ribs. As a result, the
electrode 203 is enabled to be formed at a portion which is
partitioned in advance by the barrier ribs, thereby making it
possible to inhibit the generation of short circuit between
electrodes 203.
[0292] Further, if the barrier ribs are constituted by a material
exhibiting a visible light reflectance of 50% or more, the quantity
of light to be taken up from each discharge cell can be increased.
Because, if a portion of luminescence of phosphor that might have
been leaked toward the back side of back plate can be reflected by
the barrier ribs, the light component which is available for the
display can be increased.
[0293] In the case of structure shown in FIG. 18, an additional
recessed portion is further formed at the bottom within the
U-shaped structure constituting the barrier ribs 202, and the
electrode 203 is disposed in this additional recessed portion.
According to this structure, the relative positional relationship
between the electrode 203 and the barrier ribs 202 can be defined
on the occasion of forming the barrier ribs 202. Therefore, it is
possible to obtain a plasma display panel which is accurate in
relative positional relationship between the electrode 203 and the
barrier ribs 202.
[0294] In the case of structure shown in FIG. 19, the width of the
electrode 203 is made identical with the distance (dimension of
U-shaped portion) between opposed barrier ribs 202. According to
this structure, it becomes possible to obtain a plasma display
panel where the relative positional relationship between the
electrode 203 and the barrier ribs 202 is no longer required to be
taken into account.
[0295] In the case of structure shown in FIG. 20, a metal wire or a
metal plate is employed for constituting the electrode 203. Namely,
since a metal wire, etc. which is molded in advance is employed as
the electrode, it becomes possible to obtain a plasma display panel
where the disconnection of the electrode 203 can be hardly
occurred, and even if the disconnection of the electrode 203
happens to be generated, it can be easily discovered. Further,
since a step of sintering the electrode is no longer required, the
number of steps can be reduced.
[0296] In the case of structure shown in FIG. 21, a metal wire or a
metal plate is employed for constituting the electrode 203. Namely,
since a metal wire, etc. which is molded in advance is employed as
the electrode 203, it becomes possible to obtain a plasma display
panel where the disconnection of the electrode 203 can be hardly
occurred, and even if the disconnection of the electrode 203
happens to be generated, it can be easily discovered. Further,
since a step of sintering the electrode is no longer required, the
number of steps can be reduced.
[0297] Additionally, since the relative positional relationship
between the electrode and the barrier ribs can be defined depending
on the configuration of the barrier ribs, it is advantageous in
that the step of positioning the electrode on the occasion of
forming it would be simplified.
[0298] In the case of structure shown in FIG. 22, the thickness D
of the bottom of the U-shaped structure constituting the barrier
ribs 202 is the same with or larger than the width d of upper
portion of the structure. Namely, according to this structure, the
bottom of the U-shaped structure of this embodiment is constituted
by a layer having a thickness which is the same with or larger than
the width of so-called barrier wall or barrier rib of plasma
display.
[0299] Therefore, the permeation of light to the rear side of
substrate is the same with or less than the permeation of light
through the barrier rib 202, i.e. which can be disregarded as a
matter of fact.
[0300] In the case of structure shown in FIG. 23, the thickness D
of a recessed portion formed in the bottom of the U-shaped
structure constituting the barrier ribs 202 is the same with or
larger than the width d of upper portion of the structure. Namely,
according to this structure, the permeation of light to the rear
side of substrate is the same with or less than the permeation of
light through the barrier rib 202, i.e. which can be disregarded as
a matter of fact.
[0301] In the cases of structure shown in FIGS. 24 and 25, the
thickness D in total of thickness of the bottom of the U-shaped
structure constituting the barrier ribs 202 and the thickness of
the dielectric layer 204 is the same with or larger than the width
d of upper portion of the structure. Namely, according to this
structure, the permeation of light to the rear side of substrate is
the same with or less than the permeation of light through the
barrier rib 202, i.e. which can be disregarded as a matter of
fact.
[0302] Next, examples of the second aspect of the present invention
will be explained.
EXAMPLE 8
[0303] A barrier rib paste for sand blast (PLS-3550; Nippon Denki
Gaishi Co., Ltd.) was coated on the surface of glass substrate to a
thickness of 200 .mu.m by means of screen printing method.
[0304] Then, a sand blast-resisting dry film resist (BF-703; Tokyo
Ohka Kogyo, Co., Ltd.) having a thickness of 25 .mu.m was laminated
thereon.
[0305] Then, the dry film resist was subjected to an exposure at
200 mJ/cm.sup.2 by making use of a high-pressure mercury lamp and
through a photomask having a stripe pattern of opening 150 .mu.m in
pitch and 50 .mu.m in width.
[0306] After the exposure, the development thereof was performed
using an aqueous solution of 0.2% sodium carbonate to thereby
obtain a resist pattern 150 .mu.m in pitch and 50 .mu.m in
width.
[0307] By making use of the substrate bearing this resist pattern
and a sand blast, a barrier rib paste was molded into a U-shaped
configuration.
[0308] Thereafter, by making use of a BF releasing solution (Tokyo
Ohka Kogyo, Co., Ltd.), the resist was removed, and then, the
resultant substrate was washed with water and dried.
[0309] The substrate from which the resist had been removed was
sintered in a hot-air sintering furnace at a temperature of
580.degree. C. for 20 minutes to obtain U-shaped barrier ribs as
shown in FIG. 17.
[0310] Then, a photosensitive silver paste (FODEL DC202; DuPont
Co., Ltd.) was coated all over the substrate by means of screen
printing so as to fill the interior of barrier ribs with the
paste.
[0311] In this coating step, the attack angle of squeegee was set
to 20 degrees.
[0312] In order to form an electrode pattern, upon finishing the
drying of the silver paste, the dry film resist was subjected to an
exposure at 200 mJ/cm.sup.2 by making use of a high-pressure
mercury lamp and through a photomask having a pattern of
electrode-lead-out terminals and a stripe pattern of opening 150
.mu.m in pitch and 30 .mu.m in width.
[0313] After the exposure, the development thereof was performed
using an aqueous solution of 0.2% sodium carbonate to thereby
obtain a stripe pattern 150 .mu.m in pitch and 30 .mu.m in width,
and a pattern of terminals to be led out from the stripe
pattern.
[0314] The substrate bearing the electrode pattern was sintered in
a hot-air sintering furnace at a temperature of 550.degree. C. for
20 minutes to obtain electrodes.
[0315] Then, a dielectric paste (NP-7972J; Noritake Co., Ltd.) was
coated all over the substrate bearing the electrodes by means of
screen printing. In this coating step, the attack angle of squeegee
was set to 20 degrees.
[0316] The substrate coated with the dielectric material was
sintered in a hot-air sintering furnace at a temperature of
530.degree. C. for 20 minutes to obtain a substrate having barrier
ribs, electrodes and a dielectric layer as shown in FIG. 17.
[0317] When the substrate thus obtained was evaluated, the
generation of short circuit between electrodes was not
recognized.
[0318] Neither the twisting nor collapsing of barrier ribs could
not be recognized.
[0319] Thereafter, red, green and blue phosphors were applied to
this substrate by means of screen printing, and the resultant
substrate was sintered to accomplish the back substrate.
Thereafter, transparent electrodes, bus electrodes, transparent
dielectric layer and an MgO protective coat were successively
formed on a glass substrate to prepare a front substrate. Then,
these back and front substrates were superimposed, and the
resultant composite body was subjected to evacuation and gas
charging, thereby manufacturing a plasma display panel.
EXAMPLE 9
[0320] 90 parts by weight of titanium oxide, 10 parts by weight of
glass frit, and 10 parts by weight of ethyl cellulose solution were
kneaded by means of roll mill to prepare a barrier rib paste for
sand blast, which was then coated on the surface of glass substrate
to a thickness of 200 .mu.m by means of screen printing method.
[0321] By way of the same processes as in Example 1, barrier ribs,
electrodes and a dielectric layer were fabricated. The thickness of
the bottom portion of the U-shaped barrier rib was 20 .mu.m, and
the visible light reflectance of the regions other than the regions
of electrodes was 50%.
[0322] Thereafter, red, green and blue phosphors were applied to
this substrate by means of screen printing, and the resultant
substrate was sintered to accomplish the back substrate.
Thereafter, transparent electrodes, bus electrodes, transparent
dielectric layer and an MgO protective coat were successively
formed on a glass substrate to prepare a front substrate. Then,
these back and front substrates were superimposed, and the
resultant composite body was subjected, according to the
conventional methods, to evacuation and gas charging, thereby
manufacturing a plasma display panel.
EXAMPLE 10
[0323] A barrier rib paste for sand blast (PLS-3550; Nippon Denki
Gaishi Co., Ltd.) was coated on the surface of glass substrate to a
thickness of 200 .mu.m by means of screen printing method.
[0324] Then, a sand blast-resisting dry film resist (BF-703; Tokyo
Ohka Kogyo, Co., Ltd.) having a thickness of 25 .mu.m was laminated
thereon.
[0325] Then, for the purpose of forming an electrode arrangement
portion, the dry film resist was subjected to an exposure at 200
mJ/cm.sup.2 by making use of a high-pressure mercury lamp and
through a photomask having a pattern of electrode-lead-out
terminals and a stripe pattern of opening 150 .mu.m in pitch and 30
.mu.m in width.
[0326] After the exposure, the development thereof was performed
using an aqueous solution of 0.2% sodium carbonate to thereby
obtain a stripe pattern 150 .mu.m in pitch and 30 .mu.m in width,
and a pattern of terminals to be led out from the stripe
pattern.
[0327] A barrier rib paste for sand blast (PLS-3550; Nippon Denki
Gaishi Co., Ltd.) was coated on the surface of glass substrate
(bearing thereon the resist pattern which was formed on the
aforementioned barrier rib paste) to a thickness of 180 .mu.m by
means of screen printing method.
[0328] Then, a sand blast-resisting dry film resist (BF-703; Tokyo
Ohka Kogyo, Co., Ltd.) having a thickness of 25 .mu.m was laminated
thereon.
[0329] Then, for the purpose of forming a barrier rib pattern, the
dry film resist was subjected to an exposure at 200 mJ/cm.sup.2 by
making use of a high-pressure mercury lamp and through a photomask
having a stripe pattern of opening 150 .mu.m in pitch and 50 .mu.m
in width.
[0330] By the way, in this exposure step, the position of exposure
was off-set by a pitch of 75 .mu.m in the lateral direction of the
stripe from the position of the exposure of the aforementioned
electrode pattern.
[0331] After the exposure, the development thereof was performed
using an aqueous solution of 0.2% sodium carbonate to thereby
obtain a resist pattern 150 .mu.m in pitch and 50 .mu.m in
width.
[0332] By making use of a sand blast device (Fuji Seisakusho, Co.,
Ltd.), the substrate bearing the resist pattern was worked so as to
erase a redundant portion of the barrier rib paste to a depth where
the dry film resist which was formed in the beginning was existed,
thereby molding the barrier rib paste into a U-shaped
configuration.
[0333] Thereafter, by making use of a BF releasing solution (Tokyo
Ohka Kogyo, Co., Ltd.), the resist was removed, and then, the
resultant substrate was washed with water and dried.
[0334] Since the resist which was patterned in the beginning was
also removed due to the aforementioned removal of resist, a
recessed portion for disposing an electrode was formed in the
bottom of the U-shaped structure constituting the barrier ribs.
[0335] The substrate from which the resist had been removed was
then sintered in a hot-air sintering furnace at a temperature of
580.degree. C. for 20 minutes to obtain barrier ribs constituting a
U-shaped structure having in its bottom a recessed portion for
disposing an electrode as shown in FIG. 3.
[0336] Then, a photosensitive silver paste (FODEL DC202; DuPont
Co., Ltd.) was coated all over the substrate by means of screen
printing so as to fill the interior of barrier ribs with the
paste.
[0337] In this coating step, the attack angle of squeegee was set
to 20 degrees.
[0338] In order to form an electrode pattern, upon finishing the
drying of the silver paste, the dry film resist was subjected to an
exposure at 200 mJ/cm.sup.2 by making use of a high-pressure
mercury lamp and through a photomask having a pattern of
electrode-lead-out terminals and a stripe pattern of opening 150
.mu.m in pitch and 30 .mu.m in width.
[0339] After the exposure, the development thereof was performed
using an aqueous solution of 0.2% sodium carbonate to thereby
obtain a stripe pattern 150 .mu.m in pitch and 30 .mu.m in width,
and a pattern of terminals to be led out from the stripe
pattern.
[0340] The substrate bearing the electrode pattern was sintered in
a hot-air sintering furnace at a temperature of 550.degree. C. for
20 minutes to obtain electrodes.
[0341] Then, a dielectric paste (NP-7972J; Noritake Co., Ltd.) was
coated all over the substrate bearing the electrodes by means of
screen printing. In this coating step, the attack angle of squeegee
was set to 20 degrees.
[0342] The substrate coated with the dielectric material was
sintered in a hot-air sintering furnace at a temperature of
530.degree. C. for 20 minutes to obtain a substrate having barrier
ribs, electrodes and a dielectric layer as shown in FIG. 18.
[0343] Thereafter, red, green and blue phosphors were applied to
this substrate by means of screen printing, and the resultant
substrate was sintered to accomplish the back substrate.
Thereafter, transparent electrodes, bus electrodes, transparent
dielectric layer and an MgO protective coat were successively
formed on a glass substrate to prepare a front substrate. Then,
these back and front substrates were superimposed, and the
resultant composite body was subjected to evacuation and gas
charging, thereby manufacturing a plasma display panel.
[0344] When the substrate thus obtained was evaluated, the
generation of short circuit between electrodes was not recognized.
Further, neither the twisting nor collapsing of barrier ribs could
not be recognized.
[0345] Furthermore, the relative positional relationship between
the electrode and the barrier ribs was constant all over the entire
plane, and the center in the lateral direction of the electrode was
disposed at a position which was off-set in the lateral direction
of the stripe from the center in the lateral direction of the
barrier ribs by a distance of 75 .mu.m.
EXAMPLE 11
[0346] A barrier rib paste for sand blast (PLS-3550; Nippon Denki
Gaishi Co., Ltd.) was coated on the surface of glass substrate to a
thickness of 20 .mu.m by means of screen printing method.
[0347] Then, a sand blast-resisting dry film resist (BF-703; Tokyo
Ohka Kogyo, Co., Ltd.) having a thickness of 25 .mu.m was laminated
thereon.
[0348] Then, for the purpose of forming an electrode arrangement
portion, the dry film resist was subjected to an exposure at 200
mJ/cm.sup.2 by making use of a high-pressure mercury lamp and
through a photomask having a pattern of electrode-lead-out
terminals and a stripe pattern of opening 150 .mu.m in pitch and
100 .mu.m in width.
[0349] After the exposure, the development thereof was performed
using an aqueous solution of 0.2% sodium carbonate to thereby
obtain a stripe pattern 150 .mu.m in pitch and 100 .mu.m in width,
and a pattern of terminals to be led out from the stripe
pattern.
[0350] Additionally, a barrier rib paste was coated on the surface
of substrate to a thickness of 25 .mu.m by means of screen printing
method.
[0351] Thereafter, only a region inner than the pattern of
terminals is selectively coated again with the barrier rib paste by
means of screen printing method, thus forming a layer having a
thickness of 160 .mu.m.
[0352] Then, a sand blast-resisting dry film resist (BF-703; Tokyo
Ohka Kogyo, Co., Ltd.) having a thickness of 25 .mu.m was laminated
entirely on the surface of substrate.
[0353] Then, for the purpose of forming a barrier rib pattern, the
dry film resist was subjected to an exposure at 200 mJ/cm.sup.2 by
making use of a high-pressure mercury lamp and through a photomask
having a stripe pattern of opening 150 .mu.m in pitch and 50 .mu.m
in width.
[0354] By the way, in this exposure step, the position of exposure
was off-set by a pitch of 75 .mu.m in the lateral direction of the
stripe from the position of the exposure of the aforementioned
electrode pattern.
[0355] After the exposure, the development thereof was performed
using an aqueous solution of 0.2% sodium carbonate to thereby
obtain a resist pattern 150 .mu.m in pitch and 50 .mu.m in
width.
[0356] By making use of a sand blast device (Fuji Seisakusho, Co.,
Ltd.), the substrate bearing the resist pattern was worked so as to
erase a redundant portion of the barrier rib paste to a depth where
the dry film resist which was formed in the beginning was existed,
thereby molding the barrier rib paste into a U-shaped
configuration.
[0357] Thereafter, by making use of a BF releasing solution (Tokyo
Ohka Kogyo, Co., Ltd.), the resist was removed, and then, the
resultant substrate was washed with water and dried.
[0358] The substrate from which the resist had been removed was
then sintered in a hot-air sintering furnace at a temperature of
580.degree. C. for 20 minutes to obtain barrier ribs having a
U-shaped structure and a recessed portion for the terminal as shown
in FIG. 19.
[0359] Then, a silver paste was applied to the barrier ribs to
thereby fill it in the-recessed portion by making use of an ink jet
printer.
[0360] The substrate bearing the electrode pattern was sintered in
a hot-air sintering furnace at a temperature of 550.degree. C. for
20 minutes to obtain electrodes.
[0361] Then, a dielectric paste (NP-7972J; Noritake Co., Ltd.) was
coated all over the substrate bearing the electrodes by means of
screen printing. In this coating step, the attack angle of squeegee
was set to 20 degrees.
[0362] The substrate coated with the dielectric material was
sintered in a hot-air sintering furnace at a temperature of
530.degree. C. for 20 minutes to obtain a substrate as shown in
FIG. 19.
EXAMPLE 12
[0363] According to the same process as explained in Example 8,
barrier ribs each having a U-shaped structure were prepared.
[0364] Then, a 42-6 alloy wire (42 wt. % Ni-6 wt. % Cr-52 wt. % Fe)
having a diameter of 30 .mu.m was employed as an electrode and
disposed at the bottom portion inside the recessed portion.
[0365] Then, a dielectric paste (NP-7972J; Noritake Co., Ltd.) was
coated all over the substrate bearing the electrodes by means of
screen printing. In this coating step, the attack angle of squeegee
was set to 20 degrees.
[0366] The substrate coated with the dielectric material was
sintered in a hot-air sintering furnace at a temperature of
530.degree. C. for 20 minutes to obtain a plasma display substrate
as shown in FIG. 20.
[0367] Thereafter, red, green and blue phosphors were applied to
this substrate by means of screen printing, and the resultant
substrate was sintered to accomplish the back substrate.
Thereafter, transparent electrodes, bus electrodes, transparent
dielectric layer and an MgO protective coat were successively
formed on a glass substrate to prepare a front substrate. Then,
these back and front substrates were superimposed, and the
resultant composite body was subjected to evacuation and gas
charging, thereby manufacturing a plasma display panel.
EXAMPLE 13
[0368] According to the same process as explained in Example 10,
barrier ribs each having a recessed portion which was formed in the
bottom inside a U-shaped structure were prepared.
[0369] Then, a 42-6 alloy wire (42 wt. % Ni-6 wt. % Cr-52 wt. % Fe)
having a diameter of 30 .mu.m was employed as an electrode and
fitted in the recessed portion which was formed in the bottom
inside the U-shaped structure.
[0370] Then, a dielectric paste (NP-7972J; Noritake Co., Ltd.) was
coated all over the substrate bearing the electrodes by means of
screen printing. In this coating step, the attack angle of squeegee
was set to 20 degrees.
[0371] The substrate coated with the dielectric material was
sintered in a hot-air sintering furnace at a temperature of
530.degree. C. for 20 minutes to obtain a plasma display substrate
as shown in FIG. 21.
[0372] Thereafter, red, green and blue phosphors were applied to
this substrate by means of screen printing, and the resultant
substrate was sintered to accomplish the back substrate.
Thereafter, transparent electrodes, bus electrodes, transparent
dielectric layer and an MgO protective coat were successively
formed on a glass substrate to prepare a front substrate. Then,
these back and front substrates were superimposed, and the
resultant composite body was subjected to evacuation and gas
charging, thereby manufacturing a plasma display panel.
EXAMPLE 14
[0373] A barrier rib paste for sand blast (PLS-3550; Nippon Denki
Gaishi Co., Ltd.) was coated on the surface of glass substrate to a
thickness of 70 .mu.m by means of screen printing method.
[0374] Then, a sand blast-resisting dry film resist (BF-703; Tokyo
Ohka Kogyo, Co., Ltd.) having a thickness of 25 .mu.m was laminated
thereon.
[0375] Then, for the purpose of forming an electrode arrangement
portion, the dry film resist was subjected to an exposure at 200
mJ/cm.sup.2 by making use of a high-pressure mercury lamp and
through a photomask having a pattern of electrode-lead-out
terminals and a stripe pattern of opening 150 .mu.m in pitch and
100 .mu.m in width.
[0376] After the exposure, the development thereof was performed
using an aqueous solution of 0.2% sodium carbonate to thereby
obtain a stripe pattern 150 .mu.m in pitch and 100 .mu.m in width,
and a pattern of terminals to be led out from the stripe
pattern.
[0377] Additionally, a barrier rib paste was coated on the surface
of substrate to a thickness of 25 .mu.m by means of screen printing
method.
[0378] Thereafter, only a region inner than the pattern of
terminals is selectively coated again with the barrier rib paste by
means of screen printing method, thus forming a layer having a
thickness of 160 .mu.m.
[0379] Then, a sand blast-resisting dry film resist (BF-703; Tokyo
Ohka Kogyo, Co., Ltd.) having a thickness of 25 .mu.m was laminated
entirely on the surface of substrate.
[0380] Then, for the purpose of forming a barrier rib pattern, the
dry film resist was subjected to an exposure at 200 mJ/cm.sup.2 by
making use of a high-pressure mercury lamp and through a photomask
having a stripe pattern of opening 150 .mu.m in pitch and 50 .mu.m
in width.
[0381] By the way, in this exposure step, the position of exposure
was off-set by a pitch of 75 .mu.m in the lateral direction of the
stripe from the position of the exposure of the aforementioned
electrode pattern.
[0382] After the exposure, the development thereof was performed
using an aqueous solution of 0.2% sodium carbonate to thereby
obtain a resist pattern 150 .mu.m in pitch and 50 .mu.m in
width.
[0383] By making use of a sand blast device (Fuji Seisakusho, Co.,
Ltd.), the substrate bearing the resist pattern was worked so as to
erase a redundant portion of the barrier rib paste to a depth where
the dry film resist which was formed in the beginning was existed,
thereby molding the barrier rib paste into a U-shaped
configuration.
[0384] Thereafter, by making use of a BF releasing solution (Tokyo
Ohka Kogyo, Co., Ltd.), the resist was removed, and then, the
resultant substrate was washed with water and dried.
[0385] The substrate from which the resist had been removed was
then sintered in a hot-air sintering furnace at a temperature of
580.degree. C. for 20 minutes. As a result, both of the thickness
and width of barrier rib were reduced to about 80% of those before
the sintering thereof, and hence the barrier ribs having a U-shaped
structure about 55 .mu.m in thickness at the bottom thereof and 40
.mu.m in width at an upper portion thereof were obtained.
[0386] Then, a photosensitive silver paste (FODEL DC202; DuPont
Co., Ltd.) was coated all over the substrate by means of screen
printing so as to fill the interior of barrier ribs with the
paste.
[0387] In this coating step, the attack angle of squeegee was set
to 20 degrees.
[0388] In order to form an electrode pattern, upon finishing the
drying of the silver paste, the dry film resist was subjected to an
exposure at 200 mJ/cm.sup.2 by making use of a high-pressure
mercury lamp and through a photomask having a pattern of
electrode-lead-out terminals and a stripe pattern of opening 150
.mu.m in pitch and 30 .mu.m in width.
[0389] The substrate bearing the electrode pattern was sintered in
a hot-air sintering furnace at a temperature of 550.degree. C. for
20 minutes to obtain electrodes.
[0390] Then, a dielectric paste (NP-7972J; Noritake Co., Ltd.) was
coated on the substrate bearing the electrodes by means of screen
printing, thereby filling recessed portions of barrier ribs.
[0391] In this coating step, the attack angle of squeegee was set
to 20 degrees.
[0392] The substrate coated with the dielectric material was
sintered in a hot-air sintering furnace at a temperature of
530.degree. C. for 20 minutes to obtain a substrate as shown in
FIG. 22.
[0393] Thereafter, red, green and blue phosphors were applied to
this substrate by means of screen printing, and the resultant
substrate was sintered to accomplish the back substrate.
Thereafter, transparent electrodes, bus electrodes, transparent
dielectric layer and an MgO protective coat were successively
formed on a glass substrate to prepare a front substrate. Then,
these back and front substrates were superimposed, and the
resultant composite body was subjected to evacuation and gas
charging, thereby manufacturing a plasma display panel.
[0394] When the substrate thus obtained was evaluated, the
generation of short circuit between electrodes was not recognized.
Further, neither the twisting nor collapsing of barrier ribs could
not be recognized.
EXAMPLE 15
[0395] An intaglio having a configuration which corresponds to a
reversed configuration of barrier ribs and of electrode portions
was employed as means for forming the barrier ribs. Then, a barrier
rib paste was filled in the intaglio, and the paste filled in this
manner was transferred to a substrate.
[0396] As a result, a molded body 50 .mu.m in width of an upper
portion of U-shaped structure, and 70 .mu.m in thickness at a
recessed portion formed in the bottom of U-shaped structure was
obtained.
[0397] Thereafter, when the molded body was sintered, both of the
thickness and width of barrier rib were reduced to about 80% of
those before the sintering thereof, and hence the barrier ribs
having a U-shaped structure about 55 .mu.m in thickness at the
recessed portion formed in the bottom thereof and 40 .mu.m in width
at an upper portion thereof were obtained.
[0398] Then, an alkali-soluble silver paste (FODEL DC202; DuPont
Co., Ltd.) was coated all over the substrate by means of screen
printing so as to fill the interior of barrier ribs with the
paste.
[0399] In this coating step, the attack angle of squeegee was set
to 20 degrees.
[0400] Upon finishing the drying of the silver paste, an aqueous
solution of 0.2% sodium carbonate was sprayed so as to remove all
of the silver paste except the portion of silver paste which was
filled in the recessed portion formed in the bottom of the U-shaped
structure by taking advantage of a difference in thickness of
silver paste between that formed on the bottom of the U-shaped
structure and that formed on the recessed portion formed in the
bottom of the U-shaped structure, thereby leaving the silver paste
only in the recessed portion, thus forming an electrode
pattern.
[0401] Then, the substrate was sintered in a hot-air sintering
furnace at a temperature of 550.degree. C. for 20 minutes to obtain
electrodes.
[0402] Then, a dielectric paste (NP-7972J; Noritake Co., Ltd.) was
coated on the substrate bearing the electrodes by means of screen
printing, thereby filling recessed portions of barrier ribs. In
this coating step, the attack angle of squeegee was set to 20
degrees.
[0403] The substrate coated with the dielectric material was
sintered in a hot-air sintering furnace at a temperature of
530.degree. C. for 20 minutes to obtain a substrate as shown in
FIG. 23.
[0404] Thereafter, red, green and blue phosphors were applied to
this substrate by means of screen printing, and the resultant
substrate was sintered to accomplish the back substrate.
Thereafter, transparent electrodes, bus electrodes, transparent
dielectric layer and an MgO protective coat were successively
formed on a glass substrate to prepare a front substrate. Then,
these back and front substrates were superimposed, and the
resultant composite body was subjected to evacuation and gas
charging, thereby manufacturing a plasma display panel.
EXAMPLE 16
[0405] An intaglio having a configuration which corresponds to a
reversed configuration of barrier ribs was employed as means for
forming the barrier ribs. Then, a barrier rib paste was filled in
the intaglio, and the paste filled in this manner was transferred
to a substrate.
[0406] As a result, a molded body 50 .mu.m in width of an upper
portion of U-shaped structure, and 50 .mu.m in thickness at the
bottom of U-shaped structure was obtained.
[0407] Thereafter, when the molded body was sintered, both of the
thickness and width of barrier rib were reduced to about 80% of
those before the sintering thereof, and hence the barrier ribs
having a U-shaped structure about 40 .mu.m in thickness at the
bottom thereof and 40 .mu.m in width at an upper portion thereof
were obtained.
[0408] Then, a photosensitive silver paste (FODEL DC202; DuPont
Co., Ltd.) was coated all over the substrate by means of screen
printing so as to fill the interior of barrier ribs with the
paste.
[0409] In this coating step, the attack angle of squeegee was set
to 20 degrees.
[0410] In order to form an electrode pattern, upon finishing the
drying of the silver paste, the dry film resist was subjected to an
exposure at 200 mJ/cm.sup.2 by making use of a high-pressure
mercury lamp and through a photomask having a pattern of
electrode-lead-out terminals and a stripe pattern of opening 150
.mu.m in pitch and 30 .mu.m in width.
[0411] Then, the substrate bearing the electrode pattern was
sintered in a hot-air sintering furnace at a temperature of
550.degree. C. for 20 minutes to obtain electrodes.
[0412] Then, a dielectric paste (NP-7972J; Noritake Co., Ltd.) was
coated on the substrate bearing the electrodes by means of screen
printing, thereby filling recessed portions of barrier ribs. In
this coating step, the attack angle of squeegee was set to 20
degrees.
[0413] The substrate coated with the dielectric material was
sintered in a hot-air sintering furnace at a temperature of
530.degree. C. for 20 minutes to obtain a substrate as shown in
FIG. 24. In this case, the thickness only of the dielectric
material was about 10 .mu.m, but when it was combined with the
dielectric material which was filled in the recessed portion formed
in the bottom of U-shaped structure of barrier rib, the total
thickness was about 50 .mu.m.
[0414] Thereafter, red, green and blue phosphors were applied to
this substrate by means of screen printing, and the resultant
substrate was sintered to accomplish the back substrate.
Thereafter, transparent electrodes, bus electrodes, transparent
dielectric layer and an MgO protective coat were successively
formed on a glass substrate to prepare a front substrate. Then,
these back and front substrates were superimposed, and the
resultant composite body was subjected to evacuation and gas
charging, thereby manufacturing a plasma display panel.
EXAMPLE 17
[0415] An intaglio having a configuration which corresponds to a
reversed configuration of barrier ribs and of electrodes was
employed-as means for forming the barrier ribs. Then, a barrier rib
paste was filled in the intaglio, and the paste filled in this
manner was transferred to a substrate.
[0416] As a result, a molded body 50 .mu.m in width of an upper
portion of U-shaped structure, and 50 .mu.m in thickness at the
bottom of U-shaped structure was obtained.
[0417] Thereafter, when the molded body was sintered, both of the
thickness and width of barrier rib were reduced to about 80% of
those before the sintering thereof, and hence the barrier ribs
having a U-shaped structure about 40 .mu.m in thickness at the
bottom thereof and 40 .mu.m in width at an upper portion thereof
were obtained.
[0418] Then, an alkali-soluble silver paste (FODEL DC202; DuPont
Co., Ltd.) was coated all over the substrate by means of screen
printing so as to fill the interior of barrier ribs with the
paste.
[0419] In this coating step, the attack angle of squeegee was set
to 20 degrees.
[0420] Upon finishing the drying of the silver paste, aqueous
solution of 0.2% sodium carbonate was sprayed so as to remove all
of the silver paste except the portion of silver paste which was
filled in the recessed portion formed in the bottom of the U-shaped
structure by taking advantage of a difference in thickness of
silver paste between that formed on the bottom of the U-shaped
structure and that formed on the recessed portion formed in the
bottom of the U-shaped structure, thereby leaving the silver paste
only in the recessed portion, thus forming an electrode
pattern.
[0421] Then, the substrate was sintered in a hot-air sintering
furnace at a temperature of 550.degree. C. for 20 minutes to obtain
electrodes.
[0422] Then, a dielectric paste (NP-7972J; Noritake Co., Ltd.) was
coated on the substrate bearing the electrodes by means of screen
printing, thereby filling recessed portions of barrier ribs. In
this coating step, the attack angle of squeegee was set to 20
degrees.
[0423] The substrate coated with the dielectric material was
sintered in a hot-air sintering furnace at a temperature of
530.degree. C. for 20 minutes to obtain a substrate as shown in
FIG. 25, wherein the thickness only of the dielectric material was
about 10 .mu.m, but when it was combined with the dielectric
material which was filled in the recessed portion formed in the
bottom of U-shaped structure of barrier rib, the total thickness
was about 50 .mu.m.
[0424] Thereafter, red, green and blue phosphors were applied to
this substrate by means of screen printing, and the resultant
substrate was sintered to accomplish the back substrate.
Thereafter, transparent electrodes, bus electrodes, transparent
dielectric layer and an MgO protective coat were successively
formed on a glass substrate to prepare a front substrate. Then,
these back and front substrates were superimposed, and the
resultant composite body was subjected to evacuation and gas
charging, thereby manufacturing a plasma display panel.
[0425] As explained above, according to the second aspect of the
present invention, the following effects can be obtained.
[0426] (1) It is possible to obtain a plasma display panel having a
barrier rib which can be hardly collapsed even if the width thereof
is narrowed.
[0427] (2) It is possible to obtain a plasma display panel where
the leak of luminescence to the rear side of back substrate can be
minimized.
[0428] (3) It is possible to obtain a plasma display panel where
the positional relationship between the electrode and barrier ribs
is accurate.
[0429] (4) It is possible to obtain a plasma display panel where
the disconnection and short circuit of electrodes can be
minimized.
[0430] Next, a third aspect of the present invention will be
explained.
[0431] According to this third aspect of the present invention, as
shown in FIGS. 26 and 27, anodes 303, cathodes 304 and transparent
barrier ribs 305 are disposed via a transparent dielectric material
302 on a glass back substrate 301, and a thin glass plate 306 is
placed over these components, thus sealing these components,
thereby forming a plasma addressed liquid crystal display panel. In
this case, the back plate of the plasma addressed liquid crystal
display panel is featured in that the transparent barrier ribs 305
and the transparent dielectric material 302 are formed of the same
material.
[0432] In this back plate of the plasma addressed liquid crystal
display panel, the film thickness of the transparent dielectric
material may be in the range of 3 to 15 .mu.m.
[0433] By the way, "transparent" in these transparent barrier ribs
and transparent dielectric material means that the permeability of
these materials to back light is 95% or more when they are formed
into a dielectric layer.
[0434] Further, the angle between the sidewall of the transparent
barrier rib and the glass back substrate may be set within the
range of 85 to 95 degrees. If this angle falls outside the range of
85 to 95 degrees, the plane of polarization is caused to rotate and
hence the contrast would be undesirably deteriorated.
[0435] Further, the surface roughness of the transparent barrier
rib can be controlled within 1 .mu.m, i.e. almost the optical flat
surface. If the surface roughness thereof can be controlled within
1 .mu.m, the scattering of light can be suppressed, thus enabling
both of permeating light and reflection light to be effectively
utilized. However, if the surface roughness thereof exceeds over 1
.mu.m, the scattering of light at the surface of sidewall would
become prominent, thus disturbing the plane of polarization, and
hence the contrast would be undesirably deteriorated.
[0436] The anodes and cathode to be formed on the transparent
dielectric layer can be constituted by the same material. When
these anodes and cathode are constituted by the same material, the
manufacturing process thereof can be preferably simplified.
[0437] As for the materials for constituting these anodes and
cathode, a thick film or a plating material each containing 80% or
more of Ni and exhibiting an excellent sputter resistance against
the cations of discharge gas can be employed.
[0438] Materials containing 80% or more of Ni is preferable in
terms of sputter resistance (i.e. resistance to sputtering). If the
content of Ni is less than 80%, the sputter resistance of the
material would be deteriorated, and at the same time, various
problems such as an increase of electric resistance, non-uniformity
of surface, and non-uniform discharge will be raised.
[0439] As for the materials for constituting these anodes and
cathode, it is also possible to employ a thick film or a deposition
film each containing 80% or more of Al and exhibiting an excellent
sputter resistance against the cations of discharge gas.
[0440] Materials containing, 80% or more of Al is preferable in
terms of sputter resistance (i.e. resistance to sputtering). If the
content of Al is less than 80%, the sputter resistance of the
material would be deteriorated, and at the same time, various
problems such as an increase of electric resistance, non-uniformity
of surface, and non-uniform discharge will be raised.
[0441] Among these anode and cathode which are to be formed on the
transparent dielectric layer, at least cathode may be formed of a
two-layer structure as shown in FIG. 27.
[0442] Namely, when this two-layer structure is constituted by a
first layer 304a which is formed of a material of low electric
resistance, and a second layer 304b which is formed of a material
having an excellent sputter resistance, the electric resistance of
the two-layer structure can be decreased as a whole, thereby making
it possible to make the electrode thinner and hence to increase the
aperture ratio.
[0443] Further, these anode and cathode may be formed of the same
material having a photosensitivity, and employed respectively as an
underlying electrode. In this case, at least the cathode may be
constructed such that it is provided thereon with a protective
plating containing 80% or more of Ni and exhibiting an excellent
sputter resistance against the cations of discharge gas.
[0444] Additionally, the underlying electrode can be formed using a
photosensitive Ag paste. Since this photosensitive Ag paste is
employed in large quantities at present in the production of plasma
display panel, it would be advantageous in terms of cost, and more
over, since the manufacturing process thereof is already
established, it is advantageous in easiness in handling it.
[0445] According to this third aspect of the present invention,
there is also provided a method of manufacturing a back plate of
plasma addressed liquid crystal display panel. Namely, this method
comprises the steps of coating a predetermined quantity of barrier
rib-forming paste on a surface of glass substrate; forming a
pattern of barrier ribs by pressing the barrier rib-forming paste
layer by making use of a barrier rib-forming intaglio; heating the
pattern of barrier ribs at a high temperature, thereby burning out
existing organic components and concurrently sintering glass frit
to thereby form transparent barrier ribs and a transparent
dielectric layer; and subsequently forming a cathode and an anode
on the transparent dielectric layer.
[0446] According to this third aspect of the present invention,
there is also provided another method of manufacturing a back plate
of plasma addressed liquid crystal display panel. Namely, this
method comprises the steps of filling a barrier rib-forming paste
containing glass frit in a barrier ribs-forming intaglio;
superimposing a substrate on the barrier ribs-forming intaglio
while keeping the configuration of the paste as it is to thereby
transfer the paste onto the substrate; heating the pattern of
barrier ribs, thereby burning out existing organic components and
concurrently sintering glass frit to thereby form transparent
barrier ribs and a transparent dielectric layer; and subsequently
forming a cathode and an anode on the transparent dielectric
layer.
[0447] As for the method of forming these anode and cathode, it is
possible to employ an electroless plating method.
[0448] As for the method of forming these anode and cathode, it is
also possible to employ a method which comprises the steps of:
coating a thick film paste; coating a liquid photoresist;
patterning the photoresist; forming an electrode pattern by means
of sand blast; and sintering the electrode pattern.
[0449] It is also possible, as a method of forming these anode and
cathode, to employ a photosensitive paste method.
[0450] It is also possible, as a method of forming these anode and
cathode, to employ a vapor deposition method.
[0451] In the case where at least cathode is formed of a two-layer
structure among these anode and cathode as mentioned above, it is
possible to employ, as a method of forming the underlying
electrode, a non-electrolytic plating method, a sand-blast method,
a photosensitive paste method or a vapor deposition method, which
is followed by an electrolytic plating using a material exhibiting
an excellent sputter resistance to plasma cation to thereby form a
protective plating layer.
[0452] In these methods of manufacturing the back plate of plasma
addressed liquid crystal display panel, the deposition of glass
paste for preventing the generation of-abnormal discharging at the
both ends of plasma cell can be performed at any time as long as it
is performed after the step of forming the electrode pattern. If
the electrodes are to be formed using a thick film paste, the
sintering of the glass paste should preferably be performed
concurrent with the sintering of the thick film paste for forming
the electrodes in view of reducing the number of sintering step and
of saving the manufacturing cost.
[0453] Further, if the electrodes are to be formed using a thick
film paste, the coating of the thick film paste should be performed
prior to the sintering of the barrier ribs, and the sintering of
the barrier ribs and the electrodes should be performed
concurrently in view of reducing the number of sintering step and
of saving the manufacturing cost.
[0454] However, since the barrier ribs are mechanically fragile
before the sintering thereof, the barrier ribs are required to be
carefully handled before the sintering thereof. Therefore, it may
be sometimes advisable, in view of total cost including the yield,
to form the electrodes after finishing the preliminary sintering of
the barrier ribs. Any ways, the process of forming the electrodes
should be suitably selected taking these circumstances into
consideration.
[0455] As for the materials for the electrodes, materials such as
Ni, Al or lanthanum boride, which are excellent in resistance to
the sputtering by the cation on the occasion of plasma etching, are
desirable in view of the present operating conditions of panel such
as the pulse of driving voltage, discharge current and the kinds of
discharge gas. However, if it becomes possible in future to reduce
the intensity and frequency of sputtering through the control of
driving system, a metallic material such as Au, Ag, Cu, etc. or an
alloy thereof can be employed as it is for the cathode. Therefore,
the materials for the electrode should be suitably selected taking
account of various conditions such as the easiness of patterning,
the aperture ratio, the lead-out of terminals, the hermetic sealing
properties relative to glass and the manufacturing cost.
[0456] As for the method of coating the Ni- or Al-thick film paste,
it may be a solid printing by means of screen printing method, or a
coating method using a die coater. As for the thick film paste, it
may be those which are now developed for use in a plasma display
panel. For example, it may be cathode type "Ni paste 9538" (DuPont,
Co., Ltd.), cathode type "Ni paste NP9284" (Noritake, Co., Ltd.),
or cathode type "Al paste NP9203" (Noritake, Co., Ltd.).
[0457] As for the method of coating the photosensitive elect-rode
paste, it may be a solid printing by means of screen printing
method, or a coating method using a die coater. As for the
photosensitive electrode paste, it may be those which are now
developed for use in a plasma display panel. For example, in the
case of photosensitive Ag electrode, it may be alkali-development
type "Fordel" (DuPont, Co., Ltd.), alkali-development type "TR2912"
or "TR1952" (Taiyo Ink Manufacturing, Co., Ltd.), or
water-development type "NP4701" (Noritake, Co., Ltd.).
[0458] As for the transparent barrier rib-forming material, it is
possible to employ a paste-like material comprising a low melting
point glass frit, a transparent inorganic aggregate and a binder. A
solvent for adjusting viscosity may be added to the paste-like
material for enabling the paste-like material to be coated on the
glass substrate or to be filled in the barrier rib-forming
intaglio. Depending on circumstances, the inorganic aggregate may
not necessarily be employed.
[0459] As for the transparent inorganic aggregate, it is possible
to employ SiO.sub.2 powder, or
Al.sub.2O.sub.3-B.sub.2O.sub.3-SiO.sub.2 type glass powder. The
mixing ratio of the transparent inorganic aggregate is preferably
in the range of 5 to 30% by weight.
[0460] As for the method of curing the paste, while taking the
transferring step into consideration, it can be performed by making
use of, as a binder, a thermosetting resin or a photosensitive
resin.
[0461] As for the barrier rib-forming intaglio, while taking the
steps into consideration, a suitable kind of intaglio can be
selected from a mold, a ceramic mold, an ionizing radiation-curable
resin sheet intaglio and a silicone rubber intaglio.
[0462] For example, in the case of the barrier rib-forming intaglio
which is employed in a method where a barrier rib-forming paste is
coated on a glass substrate, and then, the coated layer is pressed
by making use of a barrier rib-forming intaglio, it is preferable
to employ a mold or a ceramic mold which is capable of withstanding
the pressure of press on the occasion of molding the barrier
rib-forming paste.
[0463] As for the mold, it can be manufactured by any suitable
methods such as electronic engraving, etching, milling, rotary
lathe machining, electroforming, etc. As for the ceramic mold, it
can be manufactured by any suitable methods such as rotary lathe
machining, slurry method, etc.
[0464] It would be effective, for the purpose of enhancing the
releasability of molded product from mold after finishing the
molding of barrier ribs, to apply a silicone film or a fluorine
film to the surface of an intaglio such as a mold or a ceramic
mold.
[0465] In the case of the barrier rib-forming intaglio which is
employed in the aforementioned method where a barrier rib-forming
paste is filled in a barrier rib-forming intaglio, it is possible
to employ an ionizing radiation-curable resin sheet intaglio or a
silicone rubber intaglio, other than the aforementioned mold or
ceramic mold.
[0466] The aforementioned mold or ceramic mold is accompanied with
a problem that the cost for manufacturing them is relatively high
and hence is limited in terms of manufacturing capacity. Whereas in
the cases of the ionizing radiation-curable resin sheet intaglio
and silicone rubber intaglio, the replication thereof is relatively
easy, so that they are suited for mass-production.
[0467] Specifically, these intaglios can be produced through the
transfer thereof from a convex type matrix having the configuration
of barrier ribs as explained below. Therefore, the convex type
matrix is manufactured in conformity with a pattern of desired
barrier ribs. Namely, the convex type matrix may be such that can
be produced by lathing a metal roll into a configuration of barrier
ribs, that can be produced by cutting a flat plate into a
configuration of barrier ribs, or that can be produced by way of
photolithography after adhering a dry film onto a flat
substrate.
[0468] As for the method of coating a predetermined quantity of
barrier rib-forming paste on a glass substrate, it may be a solid
printing by means of screen printing method, or a coating method
using a die coater. Alternatively, a material formed into a film
may be laminated on the glass substrate. As for the method of
press, the employment of a flat press or a roll press is
preferable. For the purpose of preventing the entrapment of air
bubbles, it may be effective to perform the press in a vacuum
chamber.
[0469] After the paste has been cured by means of heat or
ultraviolet rays, the cured paste is taken out of the mold and
sintered to thereby simultaneously forming the transparent barrier
ribs and the transparent dielectric layer. On this occasion, the
thickness of the transparent dielectric layer is determined
depending on the pressure and pressing time by the flat press or
roll press, as well as on the hardness of the paste.
[0470] As it is correlated with the diameter of glass frit, if the
thickness of the paste is smaller than 5 .mu.m before sintering, a
region where the paste is missing would be generated, or
non-uniformity in thickness of the paste tends to be generated
after the sintering. On the other hand, if the thickness of the
paste is larger than 15 .mu.m after sintering, the permeability
would be deteriorated down to as low as 95%, thus deteriorating the
utilization efficiency of the backlight.
[0471] Therefore, it is preferable to suitably determine the
conditions of press and the composition of the barrier rib-forming
paste so as to make the thickness of the transparent dielectric
layer fall within the range of 3 to 15 .mu.m after the sintering
thereof.
[0472] As for the method of filling a predetermined quantity of the
barrier rib-forming paste in the barrier rib-forming intaglio, it
is possible to employ various coating methods, specific examples
thereof including screen printing, die-coating, doctor blade
coating, roll coating, roll press, flat press, etc. For the purpose
of preventing the entrapment of air bubbles, it may be effective to
perform the coating in a vacuum chamber.
[0473] On this occasion, the thickness of the transparent
dielectric layer is determined depending on the Theological
property of the paste, and on the magnitude of pressure and
pressing speed of the coating. As it is correlated with the
diameter of glass frit, if the thickness of the paste is smaller
than 5 .mu.m before curing, a region where the paste is missing
would be generated, or non-uniformity in thickness of the paste
tends to be generated after the sintering. On the other hand, if
the thickness of the paste is larger than 15 .mu.m after sintering,
the permeability would be deteriorated down to as low as 95%, thus
deteriorating the utilization efficiency of the backlight.
[0474] Therefore, it is preferable to suitably determine the
conditions of press and the composition of the barrier rib-forming
paste so as to make the thickness of the transparent dielectric
layer fall within the range of 3 to 15 .mu.m after the sintering
thereof.
[0475] Then, the transfer of the paste onto the substrate is
performed. In this case, any of the following methods can be
selected, i.e. a method wherein the barrier rib-forming material is
allowed to cure before the barrier rib-forming material is
transferred onto the glass substrate; and a method wherein the
barrier rib-forming material is allowed to contact with the glass
substrate before the barrier rib-forming material is still in an
uncured state, and under this condition, the barrier rib-forming
material is allowed to cure.
[0476] In the case of the former transfer method, an adhesive or a
self-adhesive is required to be interposed between the barrier
rib-forming material and the glass substrate. In the case of the
latter transfer method however, since the barrier rib-forming
material is allowed to cure on the glass substrate 104, the
adhesive or the self-adhesive is no longer required to be employed.
However, the adhesive or the self-adhesive may be employed for the
purpose of ensuring the transfer of pattern on the occasion of
releasing the paste from the intaglio. The cured paste is then
taken out of the intaglio and subjected to the sintering thereof,
thus making it possible to simultaneously obtain the transparent
barrier ribs and the transparent dielectric layer.
[0477] As explained above, according to this third aspect of the
present invention, it is possible to form both of these transparent
barrier ribs and transparent dielectric layer by making use of the
same material. Finally, anodes and cathodes are formed on the
surface of the transparent dielectric layer to accomplish the
fabrication of the plasma addressed liquid crystal display
panel.
[0478] The step of forming these electrodes can be performed prior
to the step of sintering these transparent barrier ribs and
transparent dielectric layer. However, in view of the stability in
this step, the step of forming these electrodes should preferably
be performed after the aforementioned sintering step.
[0479] As for the method of patterning the electrodes by means of
non-electrolytic plating method on the occasion of forming these
anodes and cathodes, the following methods can be preferably
employed.
[0480] Namely, the first method is performed in such a way that
after a non-electrolytic plating has been performed all over the
surface of substrate, a liquid photoresist is coated thereon, and
then, the exposure and development thereof are performed using a
mask, after which a redundant portion of the plated film was etched
away to obtain an electrode pattern.
[0481] The second method is performed in such a way that after a
liquid photoresist is coated all over the surface of substrate, the
exposure and development thereof are performed using a mask. Then,
only the regions where a plating is required to be performed are
removed, and a plating catalyst is coated all over the surface of
substrate, after which the resist is peeled away so as to leave the
plating catalyst only on the regions which correspond to the
configuration of the electrode pattern. Thereafter, the plating of
electrode of predetermined configuration is performed by means of
non-electrolytic plating. Since the electrode pattern is formed by
way of plating in this method, the sintering step is no longer
required.
[0482] In the case where these anodes and cathodes are to be formed
by a method wherein a thick film paste is employed, the coating of
the thick film paste may be performed by means of screen printing
method, solid printing method, or a coating method using a die
coater. Meanwhile, the coating of liquid photoresist can be
performed also by means of screen printing method, solid printing
method, or a coating method using a die coater.
[0483] According to the aforementioned method, the exposure of the
resist is performed using a glass mask at first, and then, the
resist is developed to form a pattern, after which by taking
advantage of the protection layer of resist, an electrode pattern
is formed by means of sand blast. However, this sand blast may be
replaced by a liquid honing. Finally, the sintering of the paste is
performed to turn it into electrodes.
[0484] In the case where these anodes and cathodes are to be formed
by a method wherein a photosensitive paste method is employed, a
pattern may be formed through a glass mask exposure using an
ordinary method, the pattern thus obtained being subsequently
sintered to turn it into the electrodes.
[0485] In the case where the method of forming anodes and cathodes
is constituted by a vapor deposition method, either a method of
depositing an electrode pattern through a liquid photoresist
masking a redundant region, or a method of depositing an electrode
pattern through a metallic mask covering a redundant region can be
preferably employed. Further, even if the masking of the sidewalls
of transparent barrier ribs are insufficient, little problem will
be raised, since there is a little possibility that due to the
configuration of the transparent barrier ribs, metal vaporized can
adhere to the sidewalls thereof. Even if the sidewalls of the
barrier ribs are adhered with a thin layer of metal, only the
redundant portion thereof can be easily removed using an etching
solution. Since the electrodes are formed of a vapor deposition
film, the sintering thereof is no longer required.
[0486] When an electrolytic plating method is employed, an ordinary
electric current can be applied by taking advantage of the
terminals of patterned electrodes, thereby making it possible to
form a protective plated film only in the regions required. Since
the electrodes are formed of a plated metal, the sintering thereof
is no longer required.
[0487] As explained above, according to the third aspect of the
present invention, the transparent barrier ribs and the transparent
dielectric layer are formed in advance using the same material, and
then, the anodes and the cathode are formed on the transparent
dielectric layer to thereby accomplish the back plate of plasma
display liquid crystal panel.
[0488] Next, examples according to the third aspect of the present
invention will be explained as follows. It should be noted that
these examples are not intended to limit the scope of the present
invention.
EXAMPLE 18
[0489] The glass back substrate of 42-inch VGA plasma display
liquid crystal panel having a panel structure as shown in FIG. 26
was manufactured by adopting the manufacturing method of
transparent barrier ribs and dielectric layer shown in FIG. 28 and
the manufacturing method of electrodes shown in FIG. 29. Followings
are detailed explanation of the manufacturing steps of the
panel.
[0490] Specifications of the barrier rib-forming intaglio:
[0491] The type of intaglio: Intaglio for press-molding;
[0492] The configuration of grooves: Stripe-shaped, 100 .mu.m in
width, 250 .mu.m in depth and 1092 .mu.m in pitch.
[0493] The surface of the intaglio was coated with fluororesin so
as to improve the releasability thereof, the resultant intaglio
being employed as a press mold.
12 The composition of barrier rib-forming paste: Low melting point
glass frit (PbO--B.sub.2O.sub.3--SiO.sub.2 70 parts by weight type
glass powder (3 .mu.m or less)): Transparent inorganic aggregate 10
parts by weight (Al.sub.2O.sub.3--B.sub.2O.sub.3--SiO.sub.2 type
glass powder (1 .mu.m or less)): Binder (ethyl cellulose): 5 parts
by weight Binder (thermosetting epoxy resin): 5 parts by weight
Viscosity adjusting solvent (butyl acetate 10 parts by weight
carbitol):
[0494] This composition was fully kneaded by making use of a roll
mill to thereby obtain a barrier rib-forming paste.
[0495] A heat resistance glass substrate provided with an exhaust
pipe-connecting hole was washed and dried. Then, the aforementioned
transparent barrier rib-forming paste was solid-coated on this
glass substrate to a thickness of 30 .mu.m by means of screen
printing. Then this glass substrate was heated at a temperature of
120.degree. C. to remove the solvent, thereby forming a uniform
film having a thickness of 25 .mu.m.
[0496] Then, by making use of the aforementioned mold having
recessed portions, this film was flat-pressed at a pressure of 10
MPa. One minute later after the initiation of this flat press, the
film was heated for two minutes at a temperature of 160.degree. C.
to thermally cure the epoxy resin. Then, the pressing was released,
and the glass substrate was released from the press mold by making
use of vacuum suction.
[0497] As a result, a configuration of transparent barrier rib 250
.mu.m in height, 100 .mu.m in width and 1092 .mu.m in pitch was
formed, and at the same time, a transparent dielectric layer having
a thickness of 15 .mu.m was formed. The resultant body was sintered
in a sintering furnace for 30 minutes at a temperature of
600.degree. C. As a result, it was possible to form smooth
transparent barrier ribs each having a height of 200 .mu.m, a width
of 80 .mu.m, a thickness of 1 .mu.m or less, and extending upward
at a angle of 88 degrees to the glass substrate, i.e. substantially
perpendicular to the glass substrate.
[0498] Further, it was also possible to form a smooth film, i.e. a
transparent dielectric layer having a thickness 12 .mu.m and a
permeability of 95%.
[0499] The glass substrate provided with the aforementioned
transparent barrier ribs and transparent dielectric layer that had
been sintered as mentioned above was then subjected to washing and
drying. In this case, for the purpose of lowering the viscosity of
the cathode Ni paste NP9284 (Noritake Co., Ltd.), 10% by weight of
butyl acetate carbitol was added therein. The resultant Ni paste
was solid-coated by means of screen printing method.
[0500] Since the viscosity was lowered in this manner, it was
possible to substantially prevent the paste from adhering to the
sidewall of the transparent barrier ribs, thus allowing the paste
to be collected at the bottom portion of the transparent barrier
ribs. Then, the paste was dried to form a Ni paste layer having a
thickness of 60 .mu.m.
[0501] Subsequently, a photosensitive liquid resist (OFPR800; Tokyo
Ohka Kogyo Co., Ltd.) was coated thereon and dried, after which by
making use of a glass mask and by keeping a proximity gap of 300
.mu.m from the glass plane (a gap from the top of barrier rib is
100 .mu.m), a parallel light was irradiated onto the surface of the
substrate, which was followed by a development process to obtain a
pattern.
[0502] By the way, the pattern to be obtained from the employment
of this glass mask would become such that the width of electrode is
100 .mu.m after the sintering. Further, since an abnormal discharge
preventive cover glass was subsequently coated as explained
hereinafter, it was designed such that a Ni thick film electrode
could be formed at a region 5 mm inner than the edge of the barrier
rib pattern.
[0503] Then, after a redundant portion of Ni electrode material was
removed by means of sand blast method, the resist was peeled away.
During this step, the Ni paste that had been adhered onto the
sidewall could be completely removed. As a result, it was possible
to obtain a stripe-shaped Ni electrode pattern which corresponded
to the anode and the cathode in the discharge space.
[0504] Since it was difficult to perform a vacuum sealing with this
Ni electrode, a Ag electrode to be provided for the sealing portion
and for the terminal electrode portion was formed as follows.
Namely, a photo-sensitive Ag electrode paste (TR2912; Taiyo Ink
Co., Ltd.) was solid-coated by means of screen printing method in
the regions including the end portion, sealing portion and terminal
electrode portion of the aforementioned Ni thick film paste layer,
thereby forming a Ag electrode paste layer having a thickness of 12
.mu.m.
[0505] Thereafter, glass masks are aligned with each other while
keeping a proximity therebetween, and the resultant surface was
irradiated with a dosage of 500 mJ/cm.sup.2. The electrode pattern
of this glass mask included the end portion, sealing portion and
terminal lead-out portion of the Ni thick film paste layer. By the
way, the width of the electrode was 100 .mu.m.
[0506] Next, by making use of a conveyer type spray developing
machine, the development of electrode pattern was performed 5
minutes using an aqueous solution of 0.4 wt. % Na2CO.sub.3 at a
temperature of 23.degree. C. and at a spray pressure of 0.1 MPa.
Thereafter, the resultant surface was washed with water and dried,
thereby obtaining a pattern.
[0507] Further, in order to prevent the generation of abnormal
discharge at the edge portion of plasma cell, a cover glass paste
was coated by means of screen printing at a zone 10 mm in width
located 5 mm outside the edge of barrier ribs. Then, the resultant
body was kept at a temperature of 580.degree. C. for 30 minutes,
thereby sintering the Ni paste, Ag paste and the cover glass
paste.
[0508] By the way, the thickness of the Ni electrode after the
sintering was 40 .mu.m, the thickness of the Ag electrode after the
sintering was about 6 .mu.m, and the width of each of these
electrodes was about 100 .mu.m. The electric resistance was about
500 .OMEGA. with about 1000 mm including Ni of the discharge
portion and Ag of the terminal portion. Therefore, as far as the
electric resistance is concerned, it meets the specification
thereof. Accordingly, it was possible to fabricate the plasma
substrate as shown in FIG. 26.
EXAMPLE 19
[0509] The glass back substrate of 42-inch HDTV plasma display
liquid crystal panel having a panel structure as shown in FIG. 27
was manufactured by adopting the manufacturing method of
transparent barrier ribs and dielectric layer shown in FIG. 30 and
the manufacturing method of electrodes shown in FIG. 31. Followings
are detailed explanation of the manufacturing steps of the
panel.
[0510] Specifications of the barrier rib-forming intaglio:
[0511] The type of intaglio: Plane type silicone rubber
intaglio;
[0512] The configuration of grooves: Stripe-shaped, 60 .mu.m in
width, 250 .mu.m in depth and 485 .mu.m in pitch.
[0513] By taking advantage of the releasability of the silicone
rubber intaglio, the intaglio was employed as a transferring
intaglio.
13 The composition of barrier rib-forming paste: Low melting point
glass frit 70 parts by weight (PbO--B.sub.2O.sub.3--SiO.sub.2 type
glass powder (3 .mu.m or less)): Transparent inorganic aggregate 10
parts by weight (Al.sub.2O.sub.3--B.sub.2O.sub.3--SiO.sub.2type
glass powder (1 .mu.m or less)): Binder (UV-curing resin;
diethylenegylcol 8 parts by weight dimethacrylate): Binder
(UV-curing resin; 2-hydroxypropyl 6 parts by weight acrylate):
Binder (initiator; benzophenone): 1 parts by weight Viscosity
adjusting solvent (butyl acetate 5 parts by weight carbitol):
[0514] This composition was fully kneaded by making use of a roll
mill to thereby obtain a barrier rib-forming paste.
[0515] A heat resistance glass substrate provided with an exhaust
pipe-connecting hole was washed and dried. Then, the aforementioned
transparent barrier rib-forming paste was filled in the
above-described flat intaglio made of silicon rubber by making use
of a doctor blade. As a result, the intaglio having a depth of 250
.mu.m was filled with the paste without entrapping air bubbles, and
at the same time, a film having a thickness of 7 .mu.m which was
designed to be formed into a transparent dielectric layer was
formed. Subsequently, this intaglio was superimposed on the
above-described glass substrate and flat-pressed at a pressure of
10 MPa.
[0516] Then, the laminated body consisting of the intaglio and the
glass substrate was taken out of the pressing machine, and then,
subjected, from the glass substrate side, to UV irradiation at a
dosage of 500 mJ/cm.sup.2 by making use of a UV irradiation device
to UV-cure the barrier rib paste, the resultant silicone rubber
intaglio being subsequently released from the glass substrate.
[0517] As a result, a configuration of transparent barrier rib 250
.mu.m in height, 60 .mu.m in width and 485 .mu.m in pitch was
formed, and at the same time, a transparent dielectric layer having
a thickness of 7 .mu.m was formed.
[0518] The resultant body was sintered in a sintering furnace for
30 minutes at a temperature of 600.degree. C. As a result, it was
possible to form smooth transparent barrier ribs each having a
height of 200 .mu.m, a width of 45 .mu.m, a thickness of 1 .mu.m or
less, and extending upward at a angle of 88 degrees to the glass
substrate, i.e. substantially perpendicular to the glass
substrate.
[0519] Further, it was also possible to form a smooth film, i.e. a
transparent dielectric layer having a thickness 5 .mu.m and a
permeability of 97%.
[0520] The glass substrate provided with the aforementioned
transparent barrier ribs and transparent dielectric layer that had
been sintered as mentioned above was then subjected to washing and
drying. As for the photosensitive electrode paste, a photosensitive
Ag electrode paste (TR2912; Taiyo Ink Co., Ltd.) was employed.
[0521] Then, this photosensitive Ag electrode paste was
solid-coated by means of screen printing method, and dried to form
a Ag electrode paste layer having a thickness of 12 .mu.m.
[0522] Thereafter, by making use of a vertical exposure machine,
glass masks are aligned with each other while keeping a proximity
therebetween, and the resultant surface was irradiated with a
dosage of 1000 mJ/cm.sup.2. The electrode pattern of this glass
mask included a lead-out portion and all of anode and cathode of
the plasma cell portion. By the way, the width of the electrode of
the plasma cell portion was 40 .mu.m.
[0523] Next, by making use of a conveyer type spray developing
machine, the development of electrode pattern was performed 5
minutes using an aqueous solution of 0.4 wt. % Na2CO.sub.3 at a
temperature of 23.degree. C. and at a spray pressure of 0.1 MPa.
Thereafter, the resultant surface was washed with water and dried,
thereby obtaining a pattern.
[0524] Further, in order to prevent the generation of abnormal
discharge at the edge portion of plasma cell, a cover glass paste
was coated by means of screen printing at a zone 10 mm in width
located 5 mm outside the edge of barrier ribs. Then, the resultant
body was kept at a temperature of 580.degree. C. for 30 minutes,
thereby sintering the Ag paste and the cover glass paste.
[0525] By the way, the thickness of the Ag electrode after the
sintering was 5 .mu.m, and the width thereof was about 40 .mu.m.
The electric resistance was about 300 .OMEGA. with about 1000 mm.
Therefore, as far as the electric resistance is concerned, it meets
the specification thereof.
[0526] Further, for the purpose of protecting the discharging
cathodes from the anion sputtering, a Ni layer having about 5 .mu.m
was formed on cathode portions of the plasma cell by means of
electrolytic plating using a sulfamic acid Ni plating bath. As a
result, cathodes each having a height of about 10 .mu.m and a width
of about 50 .mu.m were obtained. Accordingly, it was possible to
fabricate the plasma substrate as shown in FIG. 27. The aperture
ratio was 80%, indicating an excellent result.
[0527] As explained above, when the barrier ribs and electrodes are
formed by way of the manufacturing method of the third aspect of
the present invention, the following effects can be obtained.
[0528] Namely, since the transparent barrier ribs are employed, the
aperture ratio can be increased and the brightness of panel can be
improved. Additionally, the viewing angle in the direction
perpendicular to the barrier rib can be enlarged. Since it is
possible to adopt a intaglio manufacturing method where the height
of barrier ribs can be easily made uniform, the yield and stability
in quality of product can be improved. Although it has been
difficult to align the barrier ribs with the electrodes in the
process using an intaglio, it is now possible according to this
manufacturing method to obtain the panel which is excellent in
alignment precision, since the electrodes are formed after the
formation of the barrier ribs.
[0529] Next, the fourth aspect of the present invention will be
explained with reference to the drawings.
[0530] According to this fourth aspect of the invention, there is
provided a recessed and projected pattern-forming apparatus of
rotary type for forming a cured recessed and projected pattern of
an ionizing radiation-curable resin composition on the surface of a
rigid plate such as a substrate to be employed for a plasma display
or a plasma addressed liquid crystal display. This apparatus is
featured as having the following mechanisms and structures (1) to
(6).
[0531] (1) An intaglio-rotating roll provided on the surface
thereof with a predetermined recessed and projected pattern
constituted by a releasable surface;
[0532] (2) A pinching mechanism for enabling the ionizing
radiation-curable resin composition to be continuously pinched
between said intaglio-rotating roll and an ionizing
radiation-permeable releasable film while keeping a predetermined
thickness of said ionizing radiation-curable resin composition;
[0533] (3) An radiation irradiating mechanism for irradiating an
ionizing radiation to said resin composition under the
aforementioned pinched condition;
[0534] (4) A releasing mechanism for releasing said ionizing
radiation-permeable releasable film from the surface of said
intaglio-rotating roll after finishing the curing of said ionizing
radiation-curable resin composition;
[0535] (5) A press mechanism which is designed such that said rigid
plate is fed over said intaglio-rotating roll for enabling said
rigid plate to be superimposed and aligned, at a predetermined
precision, with said ionizing radiation-curable resin composition
that has been cured by said ionizing radiation, and that the
resultant composite thus aligned is placed into a compressed state;
and
[0536] (6) A releasing mechanism for enabling said rigid plate to
be released from the surface of said intaglio-rotating roll after a
termination of said compressed state.
[0537] In this recessed and projected pattern-forming apparatus, by
the term "ionizing radiation", it is meant a radiation which is
capable of exciting air or molecules so as to turn them into an
ionized state, such as UV ray, X-ray, electron beam, etc. Further,
by the term "ionizing radiation-curable resin composition", it is
meant a composition containing a resin which is capable of taking
place a curing reaction as it is irradiated with an ionizing
radiation.
[0538] By the term "releasable surface", it is meant a surface
which enables a cured product of an ionizing radiation-curable
resin composition to be very easily released from a mold. For
example, this surface may be constituted by silicone resin,
fluororesin, polyolefin resin or polyester resin. These resins can
be formed on the surface of an intaglio. Actually, a metallic plate
formed of aluminum, stainless steal, Invar alloy; or plastic film
formed of polyester resin, etc. can be employed as a substrate
plate, on the surface of which a recessed pattern of the
aforementioned releasable material can be formed.
[0539] As for the method of preparing the aforementioned intaglio,
it is possible to employ a lift-off method or a casting method
using a matrix. This lift-off method is a method wherein a pattern
inverted of a desired pattern is formed on the surface of a
printing matter at first, and then, a releasable material is coated
all over this inverted pattern and subsequently allowed to cure,
after which the inverted pattern is finally peeled away from the
printing matter to thereby obtain an aimed intaglio.
[0540] The thickness of the elastic layer which enables it to
follow a rigid plate should be such that although it may differ
depend on the non-uniformity in thickness (between lots, between
substrates, or within the same substrate), the elastic layer is
enabled to retain an elasticity thereof at least within the range
of non-uniformity of thickness. A tolerable range of deformation of
the recessed pattern is preferably: (tolerable range of
non-uniformity of thickness)+(the thickness which is 2 to 5 times
as large as the depth of recessed portion).
[0541] When expressed numerically, the thickness of the elastic
layer should be 0.5 to 3 mm in the case of the substrate for the
plasma display panel.
[0542] As for the method of turning the surface of intaglio into a
releasable surface, there are two methods, i.e. a method of forming
a recessed and projected pattern of silicon resin directly on the
surface of intaglio-rotating roll; and a method wherein a recessed
and projected pattern of silicon resin is formed on the surface of
flexible substrate, and then, the resin pattern is wound up on the
surface of intaglio-rotating roll. As for this winding method, it
is possible to employ a method of adhering the resin pattern by
making use of an adhesive or a self-adhesive; a method of sucking
the resin pattern by using magnetic force, electric force or
vacuum; or a method which is generally employed in a rotary
printing machine. It is also possible to employ a method of holding
the resin pattern by making use of a jig.
[0543] As for the kinds of the ionizing radiation-permeable film,
it is possible to employ polyester, polyimide, etc. The thickness
of this film should preferably be, in terms of handling, in the
range of 30 to 100 .mu.m. As for the releasable film to be formed
on the surface of this film, it is preferable to employ silicone
resin. A releasable film formed of polyester film coated on the
surface thereof with silicone resin is available in the market,
most of which being useful in the present invention.
[0544] As for the composition of the ionizing radiation-curable
resin, it may differ depending on the end-use thereof. Followings
are specific examples thereof. However, the viscosity and fluidity
thereof should be such that enables the resin composition to be
filled in the intaglio.
[0545] As for the pinching mechanism for enabling the ionizing
radiation-curable resin composition to be continuously pinched
while keeping a predetermined thickness thereof, a mechanism shown
in FIG. 32 can be employed in general. Namely, it is realized by
providing a pair of back-up rolls 403a and 403b at a region where
the film 401 and the intaglio-rotating roll 402 begin to engage
with each other, and at a region where the film 401 and the
intaglio-rotating roll 402 begin to be disengaged from each other,
respectively. In this case, the provision of tension control rolls
404a to 404d are required for the adjustment of the tension of the
film 401.
[0546] As for the specific embodiment of the mechanism 405 for
irradiating an ionizing radiation under the condition where the
resin composition is kept pinched, it is possible to employ a UV
irradiation device which is desirably capable of irradiating
radiation which is uniform in luminance in the lateral direction of
the intaglio-rotating roll. For example, a UV irradiation device
which is installed in an offset printing machine using a UV-curable
ink, or a non-polarized UV irradiation device which is available
from Fusion Co., Ltd. can be preferably employed.
[0547] As for the arrangement of the UV irradiation device, that
shown in FIG. 32 can be generally employed.
[0548] As for the mechanism for releasing the ionizing
radiation-permeable film 401 from the surface of the
intaglio-rotating roll 402 after finishing the curing of the film
401, a mechanism employing a pair of back-up rolls 403a and 403b
can be used in general.
[0549] Where an accurate alignment is required, it is possible to
employ a mechanism 407 which is constructed such that a rigid plate
406 is fed over the intaglio-rotating roll 402 for enabling the
rigid plate 406 to be superimposed and aligned, at a predetermined
precision, with the ionizing radiation-curable resin composition
that has been cured by the ionizing radiation, and that the
resultant composite thus aligned is placed into a compressed
state.
[0550] As for the mechanism for enabling the rigid plate 406 to be
released from the surface of the intaglio-rotating roll 402 after
the termination of the compressed state, a guide rail 408 can be
generally employed.
[0551] As for the releasable surface agent for the
intaglio-rotating roll, silicone resin can be employed. As for the
kind of silicone resin to be employed in this case, room
temperature curing rubber which is adapted for use in templating is
most preferable, because it can be formed into an intaglio by
introducing it into a matrix and curing it subsequently. For
example, room temperature curing silicone rubber (TSE3540; Toshiba
Silicone Co., Ltd.) which has been employed in the manufacture of
decorative plywood as described in the aforementioned paragraph
related to the prior art is preferable for use in the present
invention. However, it is also possible to employ other kinds of
room temperature curing rubber, or a millable silicone rubber. What
should be taken into mind in this case is that the rubber can be
hardly swelled by an ionizing radiation-curable resin composition
to be employed.
[0552] It is possible to preliminarily apply an adhesive or a
self-adhesive to the surface of rigid plate to be transferred over
the intaglio-rotating roll. If this self-adhesive is applied all
over the surface of rigid plate, the adhesivity will be left
remained even in the region other than the region where the
projected pattern that has been transferred. Unless this adhesivity
is consumed for any other purposes to thereby eliminate this
adhesivity, the presence of this adhesive region would bring about
a problem such as the adhesion of rubber to this region. In view of
overcoming this problem, the employment of a self-adhesive which
can be cured by means of ultraviolet rays is preferable.
[0553] As a chemical composition, there is known a UV-curable
adhesive. In the case of adhesive, treatments thereof such as
heating, the spraying of solvent, etc. are required to be performed
so as to provide it with a sufficient adhesivity to pull out a
cured product of the ionizing radiation-curable resin composition
from the intaglio.
[0554] A transferring resin may be coated on the surface of the
cured resin composition. In this case, a roll-coating mechanism 409
as shown in FIG. 32 can be employed for instance. This transferring
resin composition is incapable of adhering onto silicon rubber, but
is capable of adhering onto only the region where the ionizing
radiation-curable resin composition has been cured. As for the
kinds of transferring resin, those mentioned above as being useful
for the transferring can be employed.
[0555] The width of the ionizing radiation-permeable film may be
larger than the width of the intaglio-rotating roll. It is
preferable, in view of handling, to employ an ionizing
radiation-permeable film which is wider than that of the
intaglio-rotating roll by a dimension of about 5 cm to 15 cm. If it
is constructed such that the portion of the ionizing
radiation-curable resin composition that has been placed on this
laterally extended portion is prevented from being irradiated by an
ionizing radiation, this portion of the ionizing radiation-curable
resin composition can be recovered for re-use.
[0556] It is also possible to preliminarily coat the ionizing
radiation-curable resin composition on the surface of the ionizing
radiation-permeable film having a releasability before the ionizing
radiation-permeable film is fed to the irradiation apparatus. The
purpose of this preliminarily coating of the ionizing
radiation-curable resin composition is to prevent the entrapment of
air bubbles and to feed an appropriate quantity of paste.
[0557] As for the coating method to be employed in this case, any
of roll coating, die coating and knife coating can be preferably
employed. In the employment of these coating methods, it is more
preferable to employ a method to directly coat the ionizing
radiation-curable resin composition that has been vacuum-degassed.
As for the method of preventing the entrapment of air bubbles in an
interface between the film and the paste on the occasion of coating
a paste of high viscosity, it is preferable to employ a method
wherein a liquid layer of low viscosity is coated thin on the
surface of the film before the paste of high viscosity is coated.
As for the liquid of low viscosity, water can be employed.
[0558] The quantity of paste to be coated should be adjusted so as
to minimize the quantity of paste that may be squeezed out over the
opposite sides of the ionizing radiation-permeable film.
[0559] It is also possible to preliminarily coat a self-adhesive or
an adhesive on the surface of the ionizing radiation-permeable film
having a releasability. The purpose of this preliminarily coating
is to omit the coating of a self-adhesive or an adhesive on the
surface of the rigid plate. The ionizing radiation-curable resin
composition may be further coated over the layer of self-adhesive
or adhesive. In this case, if the layer of self-adhesive or
adhesive is liquid, the entrapment of air bubbles at the interface
can be prevented. As for the coating method to be employed in this
case, any of roll coating, die coating and knife coating can be
preferably employed. After this coating, the solvent can be removed
through drying, or ultraviolet ray may be irradiated so as to
enhance the adhesive strength.
[0560] A mechanism 410 for feeding liquid may be disposed at a
region where the intaglio-rotating roll and the ionizing
radiation-curable resin composition begin to contact with each
other. The purpose of this is to prevent the entrapment of air
bubbles at this portion. As for the kind of liquid to be employed
in this case, it is selected from those which do not cause the
expansion or dissolution of the surface of intaglio. This liquid
may be such that, however, may expand or dissolve more or less the
ionizing radiation-curable resin composition. There is an occasion
where the employment of such a kind of liquid is rather preferable.
Actually, the liquid may be selected from water, an aqueous
solution containing methyl alcohol, ethyl alcohol or isopropyl
alcohol, or alcohols.
[0561] A mechanism 411 for feeding liquid may be disposed at a
region where the intaglio-rotating roll and the rigid plate begin
to contact with each other. The purpose of this is the same as that
of the mechanism for feeding liquid at a region where the
intaglio-rotating roll and the ionizing radiation-curable resin
composition begin to contact with each other. However, depending on
the kinds of the rigid plate, the liquid may be fed in a film-like
form to the rigid plate, the rigid plate being subsequently
superimposed with the intaglio.
[0562] The shifting mechanism may be constituted by an X-Y-.theta.
table having a mechanism 412 for securing the rigid plate and
designed to be moved following a guide rail 408. In this case, the
rigid plate is required to be lifted upward, so that the
X-Y-.theta. table should preferably be provided with a mechanism of
vacuum suction. As for the kinds of guide rail, the employment of a
linear guide is preferable. For the purpose of shifting the rigid
plate, a driving force such as a ball screw, an air slider, etc.
can be employed. The precision may be more or less deteriorated
though, it is also possible to employ a timing belt.
[0563] As a method of forming a recessed and projected pattern
having a mechanism of shifting the rigid plate, it is possible to
employ a method wherein an alignment mark is attached to both of
the intaglio and the rigid plate, thereby making it possible to
transfer the alignment mark of the intaglio to the rigid plate, and
to measure any misregistration between the alignment mark of the
intaglio that has been transferred to the rigid plate and the
alignment mark of the rigid plate, thereby enabling the position of
the X-Y-.theta. table holding the rigid plate to be adjusted
correspondingly so as to perform the alignment between the intaglio
and the rigid plate.
[0564] Among the alignment marks which are to be attached to
corresponding portions of both of the intaglio and the rigid plate,
the alignment mark to be attached to the intaglio is such that can
be transferred to the rigid plate. More specifically, the alignment
mark should preferably be such that can be formed in the same step
for forming a desired recessed pattern.
[0565] The material for filling the recessed portion of alignment
mark may be an ionizing radiation-curable resin composition, which
should preferably be transferred after the curing thereof in order
to make it more stable in configuration. However, since it is
important to clearly retain the plane configuration of the
alignment mark, only the alignment mark portions may be separately
formed using a waterless offset printing plate for instance.
[0566] The ionizing radiation-curable resin composition may be
selected from those which are suited for forming a fine pattern and
have a color which is suited for the measurement thereof.
[0567] The alignment is performed by a method wherein the alignment
mark of the intaglio is transferred in advance to the rigid plate,
and any misregistration between the alignment mark of the intaglio
that has been transferred to the rigid plate and the alignment mark
of the rigid plate, thereby enabling the position of the
X-Y-.theta. table holding the rigid plate to be adjusted
correspondingly so as to perform the alignment between the intaglio
and the rigid plate.
[0568] As for the rigid substrate to be employed in this fourth
aspect of the present invention, it is possible to employ a glass
plate or a print circuit-like substrate, both of which may be
preliminarily treated so as to provide the rigid substrate with a
preliminary coat or pattern.
[0569] The entrapment of air bubbles can be completely prevented by
sealing the substrate with liquid. In this case, an intaglio of
rotary system is structurally very advantageous. It becomes
possible, due to the employment of a releasable film, to leave a
cured resin on the intaglio after the curing of resin through the
irradiation of ionizing radiation. Although a self-adhesive is
employed for the transferring of cured resin, since the surface of
intaglio is formed of silicone rubber, there is little possibility
that the adhesive can adhere to the silicone rubber, thereby making
it possible to transfer the adhesive together with the cured
resin.
[0570] Next, examples according to the fourth aspect of the present
invention will be explained with reference to the drawings.
EXAMPLE 20
[0571] This example describes the manufacture of barrier ribs of
the back substrate of plasma display.
[0572] This apparatus has the following features.
[0573] (1) Intaglio-rotating roll having a diameter of 300 mm and a
width of 1000 mm. An intaglio winding set system.
[0574] (2) The employment of head of slot-coater as a device for
coating a barrier rib paste on the surface of releasable film.
[0575] (3) Ionizing radiation irradiating device.fwdarw.a UV
irradiation device (Fusion Co., Ltd.; 5 kW type; light-shielding
wall-attached device for preventing a region other than a
predetermined region from being irradiated).
[0576] (4) The X-Y-.theta. table is provided with a vacuum suction
device, with an alignment mark position-detecting mechanism, with a
set position automatic correcting mechanism (based on data from the
detecting mechanism), and with a position offset function.
Alignment accuracy: .+-.3 .mu.m.
[0577] (5) Glass substrate-shifting transferring mechanism: A belt
mechanism for receiving and securing a glass substrate that has
been set in position by the glass substrate position-setting
X-Y-.theta. table (comprising a shifting belt and a table secured
on the belt, wherein the table is provided with a function which is
capable of securing or releasing the glass substrate), and for
passing the transfer portion of the glass substrate to the
receiving portion, at which the securing of the glass substrate is
released.
[0578] The portion to be treated is shifted following the linear
guide. A gear/chain mechanism is provided wherein the driving force
is set in such a manner that the intaglio-rotating roll and the
belt are both moved at the same speed. A back-up roll which is
capable of applying a predetermined pressure is installed at the
transferring position. Since the precision specification on the
pitch between the electrode and the barrier rib is .+-.5 .mu.m, and
the precision specification on the transfer-initiating position is
.+-.100 .mu.m or so, the meandering of the belt in the lateral
direction thereof is strictly prohibited. As a result, a required
portion of the belt is allowed to move, following the linear
guide.
[0579] Materials employed:
[0580] (1) Releasable film: Polyester film 30 .mu.m in thickness
and having thereon a silicone resin-based releasable coating.
[0581] (2) Liquid to be fed to an air-bubble entrapment preventive
mechanism is water.
[0582] (3) Rigid plate: Glass substrate for plasma display panel
(PD-200; Asahi Glass Co., Ltd.; 850 mm.times.650 mm (for 4:3 type
40-inch panel), 3 mm in thickness; provided with electrodes and
alignment marks; a self-adhesive (acrylic resin, 50 .mu.m in
thickness) coated on a desired transferring region; and a
protective film laminated).
[0583] (4) Intaglio: For a plane intaglio-winding
system.fwdarw.substrate 42 alloy; 300 .mu.m in thickness.
[0584] Silicone rubber of intaglio: For room temperature curable
templating (Toshiba Silicone Co., Ltd.; TSE 3540); a cast article 2
mm in thickness; alignment marks on TAP plate; a rubber plate
employed for an underlying plate (0.5 mm in thickness); barrier rib
70 .mu.m in width, 180 .mu.m in height and 430 .mu.m in pitch. By
the way, the direction of barrier rib is set in a direction
parallel with the rotating direction of intaglio. Because it
becomes possible, in this way, to facilitate the filling of paste
into the recessed portions, to minimize the entrapment of air
bubbles, to facilitate the transferring, and to quite easily secure
the accuracy of positioning.
[0585] (5) UV-ray curable paste for barrier rib: The composition
thereof is shown in the following Table 1.
14TABLE 1 Lead borosilicate glass frit: 68 parts by weight Alumina:
12 parts by weight Ethylene oxide-added sorbitol hexaacrylate (n =
15): 8 parts by weight Polyethylene glycol #400: 8 parts by weight
t-butyl anthraquinone: 2 parts by weight Butylbenzyl phthalate: 2
parts by weight
[0586] The UV-ray curable paste for barrier rib which was vacuum
degassed was fed under pressure to the head of slot coater, thus
allowing the paste to be placed and coated on the surface of a
releasable film. The thickness of the paste was 80 .mu.m which
corresponded to the quantity of paste to be pinched between rolls.
The gap between the pinching roll and the intaglio rotating roll
was set to 50 .mu.m by means of a gap control mechanism.
[0587] Further, by making use of a releasable film tension control
roll, the tension of the releasable film was set to 0.5
kg/cm.sup.2. This magnitude of tension was determined through
experiment as being suited for controlling the thickness of the
pasted to be pinched to 50 .mu.m. The speed of pinching, i.e.
peripheral speed of the intaglio was set to 5 cm/sec.
[0588] The exposure dose of UV-ray was 1000 mJ. The pressure of the
back-up roll for laminating the film with the rigid plate was 2
kg/cm. By the way, the protective film placed on the rigid plate
was peeled away immediately before this lamination so as to
minimize the adhesion of dusts. The liquid employed was water, and
the method of feeding water was a spraying method.
[0589] The method of alignment:
[0590] (1) A spare substrate is set in such a manner that the
alignment mark which is formed simultaneous with the formation of
the electrodes (referred to hereinafter as electrode alignment
mark) can be placed inside the visual field of a CCD observation
system, this alignment mark being determined as a provisional
origin.
[0591] (2) Under this condition, the transferring is initiated.
Namely, while the substrate is kept vacuum-sucked onto the
X-Y-.theta. table, the substrate is secured to the shifting belt
(at this moment, the shifting belt is made stationary), then, the
vacuum suction by the X-Y-.theta. table is released, after which
the table is lifted up 1 to 2 mm by means of compressed air. Then,
the belt is initiated to move so as to permit the glass substrate
to pass through the transferring region to the substrate-receiving
zone. As a result, the barrier rib alignment mark is transferred to
the spare substrate.
[0592] (3) This spare substrate is permitted to return to the start
position, and any misregistration between the electrode alignment
mark (provisional origin) and the barrier rib alignment mark (true
origin) is measured, thus making it possible to set the magnitude
of offset for shifting the provisional origin to the true origin
every time.
[0593] (4) A production substrate is set in place. In this
mechanism, the electrode alignment mark is detected at first, and
the electrode alignment mark thus detected is shifted to the
provisional origin. Then, this provisional origin is shifted by a
distance corresponding to the magnitude of offset. As a result, the
true origin (barrier rib alignment mark) is superimposed on the
electrode alignment mark.
[0594] (5) Under this condition, in the same manner as on the
occasion of the spare substrate, the production substrate is
secured to the transferring belt and allowed pass through the
transferring step to thereby transfer the barrier ribs onto a
predetermined position.
[0595] (6) Thereafter, the feeding of production substrates is
repeated.
[0596] Post treatment:
[0597] The cured paste detached from the roll may be left adhered
onto a region of the substrate which is not coated with an adhesive
even after the transferring step. This residual paste is peeled
away by making use of a dust-removing adhesive roll.
[0598] (2) Thereafter, the sintering of the paste is performed.
[0599] Results:
[0600] Configuration: The barrier ribs thus formed were the same as
the configuration of the intaglio, except that the thickness of the
dielectric portion was 10.+-.20 m
[0601] Defects: Defects in the barrier ribs or other regions due to
the entrapment of air bubbles, insufficient filling, incomplete
transferring were not recognized.
[0602] Alignment accuracy relative to the electrodes: .+-.20 .mu.m
in a direction parallel with the transferring direction; .+-.5
.mu.m or less in a direction perpendicular to the transferring
direction; and the meandering of barrier ribs being .+-.5 .mu.m
based on R.
[0603] By the way, the device and method of this embodiment are
also applicable for the manufacture of the barrier ribs of the back
plate of plasma addressed liquid crystal display (PALC). It is also
possible to apply the present invention to the formation of the
paste wiring and electrodes of PDP and PALC.
[0604] Additional advantages and modifications will readily occur
to those skilled in the art. Therefore, the invention in its
broader aspects is not limited to the specific details and
representative embodiments shown and described herein. Accordingly,
various modifications may be made without departing from the spirit
or scope of the general inventive concept as defined by the
appended claims and their equivalents.
* * * * *