U.S. patent application number 12/942185 was filed with the patent office on 2011-03-03 for liquid crystal display panel and method for producing the same.
This patent application is currently assigned to SHARP KABUSHIKI KAISHA. Invention is credited to Yukio KUROZUMI, Toshihide TSUBATA, Masayuki TSUJI, Naoshi YAMADA, Hidehiko YAMAGUCHI.
Application Number | 20110051069 12/942185 |
Document ID | / |
Family ID | 35599038 |
Filed Date | 2011-03-03 |
United States Patent
Application |
20110051069 |
Kind Code |
A1 |
YAMADA; Naoshi ; et
al. |
March 3, 2011 |
LIQUID CRYSTAL DISPLAY PANEL AND METHOD FOR PRODUCING THE SAME
Abstract
The method of the present invention includes the steps of (A)
providing a first substrate, and a second substrate, wherein the
first substrate includes a first light shielding layer provided
within a non-display region, the first light shielding layer
including a light-transmitting portion provided near an outer
boundary of the first light shielding layer, the light-transmitting
portion comprising a recess or an opening; (B) drawing a seal
pattern with a sealant, the seal pattern being drawn outside the
first light shielding layer so as to surround the display region,
comprising the substeps of: (B1) beginning application of the
sealant near the light-transmitting portion, (B2) applying the
sealant along an outer periphery of the first light shielding
layer, and (B3) forming a junction with the sealant having been
applied near the light-transmitting portion; (C) applying a liquid
crystal material within the display region surrounded by the
sealant; (D) attaching the first substrate and the second
substrate; and (E) performing light irradiation from the first
substrate side to cure the sealant.
Inventors: |
YAMADA; Naoshi; (Tsu-shi,
JP) ; YAMAGUCHI; Hidehiko; (Tsu-shi, JP) ;
TSUBATA; Toshihide; (Tsu-shi, JP) ; KUROZUMI;
Yukio; (Suzuka-shi, JP) ; TSUJI; Masayuki;
(Matsusaka-shi, JP) |
Assignee: |
SHARP KABUSHIKI KAISHA
Osaka
JP
|
Family ID: |
35599038 |
Appl. No.: |
12/942185 |
Filed: |
November 9, 2010 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12835067 |
Jul 13, 2010 |
7855774 |
|
|
12942185 |
|
|
|
|
12420836 |
Apr 9, 2009 |
7782437 |
|
|
12835067 |
|
|
|
|
11180992 |
Jul 13, 2005 |
7535538 |
|
|
12420836 |
|
|
|
|
Current U.S.
Class: |
349/153 |
Current CPC
Class: |
G02F 1/133351 20130101;
G02F 1/1339 20130101; G02F 1/13415 20210101 |
Class at
Publication: |
349/153 |
International
Class: |
G02F 1/1339 20060101
G02F001/1339 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 15, 2004 |
JP |
2004-208170 |
Nov 30, 2004 |
JP |
2004-346915 |
Claims
1. A liquid crystal display panel comprising: a first substrate; a
second substrate; a liquid crystal layer interposed between the
first substrate and the second substrate; and a sealing portion
surrounding the liquid crystal layer; a light shielding layer
provided on one of the first and second substrates and including at
least one light transmission portion; wherein a width of the
sealing portion is wider at a portion of the sealing portion that
overlaps with the at least one light transmission portion; and the
at least one light transmission portion is located at a corner of
the light shielding layer.
2. The liquid crystal display panel of claim 1, wherein the at
least one light transmission portion is defined by at least one
cut-out portion of the light shielding layer.
3. The liquid crystal display panel of claim 1, wherein the at
least one light transmission portion is defined by a plurality of
cut-out portions of the light shielding layer.
4. The liquid crystal display panel of claim 3, wherein each of the
plurality of cut-out portions is located at a respective corner of
the light shield layer.
5. The liquid crystal display panel of claim 3, wherein the
plurality of cut-out portions includes: at least one cut-out
portion located at the corner of the light shielding layer: and at
least one cut-out portion located along at least one side of the
one of the first and second substrates.
6. The liquid crystal display panel of claim 1, wherein the at
least one light transmission portion is defined by at least one
recess formed in the light shielding layer.
7. The liquid crystal display panel of claim 1, wherein the at
least one light transmission portion is defined by a plurality of
recesses formed in the light shielding layer.
8. The liquid crystal display panel of claim 7, wherein each of the
plurality of recesses is located at a respective corner of the
light shield layer.
9. The liquid crystal display panel of claim 7, wherein the
plurality of recesses include: at least one recess located at the
corner of the light shielding layer; and at least one recess
located along at least one side of the one of the first and second
substrates.
10. The liquid crystal display panel of claim 1, wherein the at
least one light transmission portion is defined by at least one
opening formed in the light shielding layer.
11. The liquid crystal display panel of claim 1, wherein the at
least one light transmission portion is defined by a plurality of
openings formed in the light shielding layer.
12. The liquid crystal display panel of claim 11, wherein each of
the plurality of openings is located at a respective corner of the
light shield layer.
13. The liquid crystal display panel of claim 11, wherein the
plurality of openings includes: at least one opening located at the
corner of the light shielding layer; and at least one opening
located along at least one side of the one of the first and second
substrates.
14. The liquid crystal display panel of claim 1, wherein: the first
substrate is a color filter substrate; and the at least one light
transmission portion is provided on the first substrate.
15. The liquid crystal display panel of claim 1, wherein: the
second substrate is a thin film transistor substrate; and the at
least one light transmission portion is provided on the second
substrate.
16. The liquid crystal display panel of claim 1, wherein the at
least one light transmission portion is provided on each of the
first substrate and the second substrate.
17. The liquid crystal display panel of claim 1, wherein a portion
of the sealing portion is located in the at least one light
transmission portion.
18. The liquid crystal display panel of claim 1, further comprising
a display region and a non-display region, wherein the light
shielding layer is provided in the non-display region.
19. The liquid crystal display panel of claim 1, wherein a junction
is located in the at least one light transmission portion.
20. The liquid crystal display panel of claim 1, wherein the
sealing portion includes a sealant made of at least one of a resin,
a UV curable resin, and a photocurable resin.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a liquid crystal display
panel and a method for producing the same. More particularly, the
present invention relates to a method for producing a liquid
crystal display panel by using one drop filling technique, and a
liquid crystal display panel suitable for such a production
method.
[0003] 2. Description of the Related Art
[0004] In recent years, as liquid crystal display panels become
larger in size, it is becoming more common to adopt a so-called one
drop filling technique as a method for forming a liquid crystal
layer between a pair of substrates, instead of the
conventionally-used vacuum injection technique.
[0005] A process of producing a liquid crystal display panel using
a vacuum injection technique comprises the following steps.
[0006] (a1) On one of a pair of substrates (which typically are a
color filter substrate and a TFT substrate) for composing a liquid
crystal display panel, a predetermined pattern of sealant is
formed. Thereafter, the pair of substrates are attached together,
and the sealant is cured, whereby a liquid crystal cell is
obtained. The sealant pattern is formed so as to define a region in
which a liquid crystal layer will later be formed (note that a
display region is encompassed within this region) and also to
define an injection inlet.
[0007] (a2) After evacuating the liquid crystal cell to create a
vacuum therein, a liquid crystal material is injected while keeping
the liquid crystal material in contact with the injection inlet, by
utilizing a pressure difference between the interior and exterior
of the liquid crystal cell and also utilizing capillary action.
[0008] (a3) Thereafter, the injection inlet is sealed with an
encapsulant.
[0009] On the other hand, a one drop filling technique comprises
the following steps.
[0010] (b1) On one of a pair of substrates, a sealant pattern is
formed so as to surround a region in which a liquid crystal layer
is to be formed, and thereafter a liquid crystal material is
dripped into the region enclosed by the sealant pattern.
[0011] (b2) Then, the substantially is attached to the other
substrate, and thereafter the sealant is cured.
[0012] In the one drop filling technique, the sealant pattern needs
to completely enclose the region in which to form a liquid crystal
layer. Therefore, when a seal pattern is drawn by means of a
dispenser or the like, at least one junction will always be
formed.
[0013] With reference to FIG. 21, the characteristics of a seal
pattern used in the one drop filling technique will be
described.
[0014] FIG. 21 illustrates an example where four liquid crystal
display panels are to be formed from a mother substrate. A color
filter mother substrate 20 includes four color filter substrates.
In a display region 24 of each resultant color filter substrate,
color filters which are arranged so as to correspond to the pixels
and a counter electrode(s) (which are not shown) are provided. Each
color filter substrate further includes a light shielding layer
(black matrix) 22 surrounding the display region 24, such that the
light shielding layer 22 defines an outer periphery of the display
region 24. Although FIG. 21 only illustrates discrete TFT
substrates 10 corresponding to the respective liquid crystal
display panels, it will be appreciated that a mother substrate
including four unseparated TFT substrates 10 (in a similar fashion
to the color filter mother substrate 20) is to be attached to the
mother substrate 20 before cutting. In a display region 14 of each
of the four TFT substrates 10, necessary circuit elements, e.g.,
TFTs, pixel electrodes, gate bus lines, and source bus lines, are
formed. Each TFT substrate and each color filter substrate are
attached together by means of a sealing portion 32. The sealing
portion 32 is formed on the outside of the light shielding layer
22.
[0015] The portion of the liquid crystal display panel lying
outside of the display region 14 is referred to as a "non-display
region" or "frame region", which is expected to be as narrow as
possible. The light shielding layer 22 and the sealing portion 32
are provided in the non-display region.
[0016] On the other hand, the light shielding layer 22 needs to
have a certain thickness in order to prevent unnecessary light from
entering into the display region 14. If light shielding is
insufficient, black displaying quality is degraded, thus
substantially affecting the image quality. In order to satisfy both
of these requirements, it is necessary to accurately form the
sealing portion 22 at the close vicinity of the outer periphery of
the light shielding layer 22.
[0017] However, when the sealing portion 32 is formed by a drawing
technique, at least one junction 32b will inevitably be formed. The
sealing junction 32b tends to become thicker than a main stretch
32a of the sealing. As used herein, the sealing main stretch 32a
refers to a portion of the sealing portion 32, excluding the
junction 32b, that has a substantially constant width. The main
stretch 32a is a portion of a seal pattern that is created with a
sealant which is discharged while a nozzle of a dispenser or the
like undergoes a relative movement within the plane of the
substrate, and therefore depends on the discharged amount of
sealant and the moving speed of the nozzle. Thus, the main stretch
32a has a fairly stable width. On the other hand, the junction 32b
includes a portion at which the sealant is first applied (i.e., a
start point of the seal drawing). The amount of sealant which is
initially added depends on the amount of sealant which resides at
the tip of the nozzle. The amount of sealant residing at the tip of
the nozzle fluctuates due to fluctuations in the length of time
spent for positioning the nozzle (including positioning along the
height direction), and fluctuations in the amount of sealant which
remains at the tip of the nozzle when the nozzle is lifted off the
substrate at the end point of seal drawing. Thus, due to the
inconstancy in the amount of sealant applied at the start point and
end point of seal drawing, and the need to form a junction, the
width of the junction 32b tends to become thicker than that of the
main stretch 32a.
[0018] FIGS. 22A and 22B are enlarged views showing the
neighborhood of a sealing junction. FIG. 22A is a plan view, and
FIG. 22B is a cross-sectional view.
[0019] As described above, if the seal pattern has a broader width
at the junction 32b, a portion thereof may overlap the light
shielding layer 22. Since photocurable resins (including those
types of photocurable resin which also allow auxiliary use of
thermosetting) are widely used as the sealant, if light irradiation
(typically ultraviolet (UV) irradiation) is performed from the side
of the color filter substrate 20, the portion 32' of the sealant
which overlaps with the light shielding layer 22 cannot be
sufficiently cured. As a result, the uncured component of the
photocurable resin may elute into the liquid crystal material, thus
causing deterioration in reliability, e.g., lowering of the voltage
retention rate of the liquid crystal display panel mainly due to
ionic components, and occurrence of orientation defects.
[0020] It might be possible to perform light irradiation from the
side of the TFT substrate 10. However, as will be described later,
if UV irradiation is performed from the side of the TFT substrate
10, it becomes necessary to employ some means for preventing the
TFTs from being irradiated with UV (e.g., a mask for shielding the
TFTs from light must be used). On the other hand, if UV irradiation
is performed from the side of the color filter substrate 20, there
is an advantage in that such means can be omitted in the case where
the color filter sufficiently absorbs UV. At least the amount of
damage to the TFTs can be reduced.
[0021] In order to prevent partial overlapping between the junction
32b and the light shielding layer 22, Japanese Laid-Open Patent
Publication No. 2002-122870 discloses a method which involves
drawing a seal pattern that extends to the outside of the liquid
crystal display panel, and forming a junction 32d outside of the
liquid crystal display panel, as shown in FIG. 23. Moreover, as
shown in FIG. 24, Japanese Laid-Open Patent Publication No.
2002-122870 discloses a method which involves forming a start or
end point 32e of seal drawing outside of the liquid crystal display
panel.
[0022] Japanese Laid-Open Patent Publication No. 8-240807 discloses
a method which involves forming a sealing junction at a corner
portion, taking advantage of the fact that the interspace between a
sealing portion and a light shielding portion will be about 1.4
times greater at a corner portion of the liquid crystal display
panel than along any side thereof. However, this method cannot cope
with the above problem once the width of the sealing junction
exceeds about 1.4 times the aforementioned value, as is also
pointed out in Japanese Laid-Open Patent Publication No.
2002-122870.
[0023] If the method described in Japanese Laid-Open Patent
Publication No. 2002-122870 is used, it is no longer necessary to
form a junction 32b within the liquid crystal display panel.
However, as shown in FIG. 25A, this method is only applicable to
the case where, after a TFT substrate (TFT mother substrate) 10 is
attached to a color filter substrate (CF mother substrate) 20, both
mother substrates 10 and 20 are cut along the same line CL. There
exist other cases where, as shown in FIG. 25B, the TFT mother
substrate 10 is cut along a cut line CL1 and the CF mother
substrate 20 is cut along a cut line CL2 different from the cut,
line CL1, this being in order to provide a signal line terminal
section (driver mounting portion) on the TFT substrate 10. In such
cases, there is a problem in that a sealing portion 32t will remain
on the TFT mother substrate 10, which will stick to a fragment of
the CF mother substrate 20 to be removed, thus making it impossible
to remove the fragment. Note that in a structure where signal line
terminal sections are provided along three or four sides of the
liquid crystal display panel in order to suppress signal delays and
the like associated with an increased size of the display panel, it
is impossible to adopt the seal pattern as shown in FIG. 25A.
Although the pattern shown in FIG. 25A can be adopted in the case
where signal line terminal sections are provided along two sides of
the liquid crystal display panel, the need to cut the sealing
portion 32 concurrently with the mother substrates 10 and 20 may
invite cutting failures.
[0024] Furthermore, the method described in Japanese Laid-Open
Patent Publication No. 2002-122870 will require an apparatus which
is able to draw a seal pattern to the outside of a liquid crystal
display panel without allowing a junction to be formed before going
out of the display panel. Such a seal pattern drawing apparatus
will inevitably be large in size, and hence increase the production
cost of the display panel.
[0025] According to a study conducted by the inventors of the
present invention, the method described in Japanese Laid-Open
Patent Publication No. 8-240807 will have not only the problem
mentioned in Japanese Laid-Open Patent Publication No. 2002-122870,
but also another problem in that, as schematically shown in FIGS.
26A and 26B, the width of the sealing junction may occasionally
exceed the 1.4 times value at a corner portion, even without
forming a junction. In such cases, the sealant 32c present in the
overlapping portion with the light shielding layer 22 cannot be
sufficiently cured.
[0026] In addition to sealing junctions and corner portions,
similar methods may also occur in any transfer section for
establishing electrical connection between the upper and lower
substrates (e.g., a common transfer section).
SUMMARY OF THE INVENTION
[0027] In order to overcome the problems described above, preferred
embodiments of the present invention provide: a method for
efficiently producing a liquid crystal display panel whose
reliability will not be degraded even if a portion (e.g., a sealing
junction or transfer section) which under the conventional
production methods will result in a seal pattern having a thicker
width is formed in the liquid crystal display panel; and a liquid
crystal display panel which is provided by such a production
method.
[0028] A liquid crystal display panel production method according
to the present invention is a method for producing a liquid crystal
display panel including a first substrate, a second substrate, and
a liquid crystal layer interposed between the first substrate and
the second substrate, the liquid crystal display panel having a
display region and a non-display region surrounding the display
region, the method comprising the steps of: (A) providing the first
substrate or a first mother substrate containing the first
substrate, and the second substrate or a second mother substrate
containing the second substrate, wherein the first substrate
includes a first light shielding layer provided within the
non-display region at an end closer to the display region, the
first light shielding layer including at least one
light-transmitting portion provided near an outer boundary of the
first light shielding layer, the at least one light-transmitting
portion comprising a recess or an opening; (B) drawing a seal
pattern by using a sealant containing a photocurable resin, the
seal pattern being drawn outside the first light shielding layer of
the first substrate so as to surround the display region,
comprising the substeps of: (B1) beginning application of the
sealant near the light-transmitting portion of the first substrate,
(B2) applying the sealant along an outer periphery of the first
light shielding layer of the first substrate, and (B3) forming a
junction with the sealant having been applied near the
light-transmitting portion; (C) applying a liquid crystal material
within the display region surrounded by the sealant; (D) attaching
together the first substrate and the second substrate, with the
liquid crystal material interposed therebetween; and (E) after step
(D), performing light irradiation from the first substrate side to
cure the sealant.
[0029] In one embodiment, the first substrate has a rectangular
shape; the at least one light-transmitting portion includes a
light-transmitting portion provided at least along a side of the
rectangular shape; and the junction is formed at the
light-transmitting portion provided along the side of the
rectangular shape.
[0030] In one embodiment, the at least one light-transmitting
portion includes two or more light-transmitting portions provided
along the side of the rectangular shape; and the junction is formed
at each of the two or more light-transmitting portions formed along
the side of the rectangular shape.
[0031] In one embodiment, the at least one light-transmitting
portion further includes a light-transmitting portion provided at a
corner of the rectangular shape.
[0032] In one embodiment, the first mother substrate includes a
plurality of first substrates, the method comprising: a first
drawing step of drawing the seal pattern on one of the plurality of
first substrates by beginning application of the sealant near one
of the two or more light-transmitting portions of the first
substrate, applying the sealant along the outer periphery of the
first light shielding layer, and ending application of the sealant
near another of the two or more light-transmitting portions; a
second drawing step of drawing the seal pattern on another of the
plurality of first substrates by beginning application of the
sealant near one of the two or more light-transmitting portions of
the first substrate, applying the sealant along the outer periphery
of the first light shielding layer, and ending application of the
sealant near another of the two or more light-transmitting
portions; a third drawing step of, after the first drawing step,
drawing the seal pattern on the one first substrate by beginning
application of the sealant so as to form a junction with the
sealant having been applied near the one light-transmitting portion
or the other light-transmitting portion of the first substrate; and
a fourth drawing step of, after the second drawing step, drawing
the seal pattern on the other first substrate by beginning
application of the sealant so as to form a junction with the
sealant having been applied near the one light-transmitting portion
or the other light-transmitting portion of the first substrate.
[0033] Another liquid crystal display panel production method
according to the present invention is a method for producing a
liquid crystal display panel including a first substrate, a second
substrate, and a liquid crystal layer interposed between the first
substrate and the second substrate, the liquid crystal display
panel having a display region and a non-display region surrounding
the display region, the method comprising the steps of: (A)
providing the first substrate or a first mother substrate
containing the first substrate, and the second substrate or a
second mother substrate containing the second substrate, wherein
the first substrate includes, a first light shielding layer
provided within the non-display region at an end closer to the
display region, the first light shielding layer including at least
one light-transmitting portion provided near an outer boundary of
the first light shielding layer, the at least one
light-transmitting portion comprising a recess or an opening; (B)
drawing a seal pattern by using a sealant containing a photocurable
resin, the seal pattern being drawn in a region of the second
substrate to be located outside the first light shielding layer of
the first substrate when the second substrate is attached to the
first substrate, and the seal pattern being drawn so as to surround
the display region, comprising the substeps of: (B1) beginning
application of the sealant near a position corresponding to the
light-transmitting portion of the first substrate, (B2) applying
the sealant along a region corresponding to an outer periphery of
the first light shielding layer of the first substrate, and (B3)
forming a junction with the sealant having been applied near the
position corresponding to the light-transmitting portion; (C)
applying a liquid crystal material within the display region
surrounded by the sealant; (D) attaching together the first
substrate and the second substrate, with the liquid crystal
material interposed therebetween; and (E) after step (D),
performing light irradiation from the first substrate side to cure
the sealant.
[0034] In one embodiment, the first substrate has a rectangular
shape; the at least one light-transmitting portion includes a
light-transmitting portion provided at least along a side of the
rectangular shape; and the junction is formed at a position
corresponding to the light-transmitting portion provided along the
side of the rectangular shape.
[0035] In one embodiment, the at least one light-transmitting
portion includes two or more light-transmitting portions provided
along the side of the rectangular shape; and the junction is formed
at a position corresponding to each of the two or more
light-transmitting portions formed along the side of the
rectangular shape.
[0036] In one embodiment, the at least one light-transmitting
portion further includes a light-transmitting portion provided at a
corner of the rectangular shape.
[0037] In one embodiment, the second mother substrate includes a
plurality of second substrates, the method comprising: a first
drawing step of drawing the seal pattern on one of the plurality of
second substrates by beginning application of the sealant near a
position corresponding to one of the two or more light-transmitting
portions of the first substrate, applying the sealant along the
region corresponding to the outer periphery of the first light
shielding layer, and ending application of the sealant near a
position corresponding to another of the two or more
light-transmitting portions; a second drawing step of drawing the
seal pattern on another of the plurality of second substrates by
beginning application of the sealant near a position corresponding
to one of the two or more light-transmitting portions of the first
substrate, applying the sealant along the region corresponding to
the outer periphery of the first light shielding layer, and ending
application of the sealant near a position corresponding to another
of the two or more light-transmitting portions; a third drawing
step of, after the first drawing step, drawing the seal pattern on
the one second substrate by beginning application of the sealant so
as to form a junction with the sealant having been applied near the
position corresponding to the one light-transmitting portion or the
position corresponding to the other light-transmitting portion of
the first substrate; and a fourth drawing step of, after the second
drawing step, drawing the seal pattern on the other second
substrate by beginning application of the sealant so as to form a
junction with the sealant having been applied near the position
corresponding to the one light-transmitting portion or the position
corresponding to the other light-transmitting portion of the first
substrate.
[0038] In One embodiment, the liquid crystal display panel has a
broad-gap region within the non-display region, the broad-gap
region being a region in which a gap between the first substrate
and the second substrate is partially increased, the broad-gap
region comprising a dent in surface of the first substrate or the
second substrate; and the at least one light-transmitting portion
includes a light-transmitting portion provided near the broad-gap
region.
[0039] In one embodiment, the liquid crystal display panel
production method further comprises a step of applying a transfer
material containing a photocurable resin to the first substrate or
the second substrate for forming a transfer section for
establishing electrical connection between the first substrate and
the second substrate, wherein the transfer material is applied in
the dent.
[0040] In one embodiment, the liquid crystal display panel
production method further comprises a step of applying a transfer
material containing a photocurable resin to the first substrate or
the second substrate for forming a transfer section for
establishing electrical connection between the first substrate and
the second substrate, wherein the transfer material is applied at a
position on the first substrate near the at least one
light-transmitting portion, or near a position on the second
substrate corresponding to the light-transmitting portion of the
first substrate.
[0041] In one embodiment, step (E) comprises a substep of curing
the transfer material via the light irradiation.
[0042] In one embodiment, the transfer section is formed so as to
at least partially overlap with the seal pattern.
[0043] In one embodiment, the second substrate includes at least
one second light shielding layer in the non-display region, the at
least one second light shielding layer being provided in a region
corresponding to the at least one light-transmitting portion of the
first substrate.
[0044] In one embodiment, the second substrate includes a source
bus line and a gate bus line; and the at least one second light
shielding layer comprises a same conductive layer as that of the
source bus line or the gate bus line.
[0045] In one embodiment, the at least one light-transmitting
portion comprises a plurality of recess or openings, the second
light shielding layer further including light-transmitting portions
provided corresponding to interspaces between, or neighborhoods of,
the plurality of recesses or openings, the method further
comprising, after step (D), a step of performing light irradiation
from the second substrate side.
[0046] A still another liquid crystal display panel production
method according to the present invention is a method for producing
a liquid crystal display panel including a first substrate, a
second substrate, and a liquid crystal layer Interposed between the
first substrate and the second substrate, the liquid crystal
display panel having a display region, a non-display region
surrounding the display region, and a broad-gap region within the
non-display region, the broad-gap region being a region in which a
gap between the first substrate and the second substrate is
partially increased, the broad-gap region comprising a dent in a
surface of the first substrate or the second substrate, the method
comprising the steps of: (A) providing the first substrate or a
first mother substrate containing the first substrate, and the
second substrate or a second mother substrate containing the second
substrate, wherein the first substrate includes a first light
shielding layer provided within the non-display region at an end
closer to the display region; (B) drawing a seal pattern by using a
sealant containing a photocurable resin, the seal pattern being
drawn outside the first light shielding layer of the first
substrate having the dent, or the seal pattern being drawn in a
region of the second substrate to be located outside the first
light shielding layer of the first substrate when the second
substrate having the dent is attached to the first substrate, the
seal pattern being drawn so as to surround the display region,
comprising the substeps of: (B1) beginning application of the
sealant near the dent of the first substrate or the second
substrate, (B2) applying the sealant along an outer periphery of
the first light shielding layer of the first substrate, or along a
region on the second substrate corresponding to the outer periphery
of the first light shielding layer of the first substrate, and (B3)
forming a junction with the sealant having been applied near the
dent; (C) applying a liquid crystal material within the display
region surrounded by the sealant; (D) attaching together the first
substrate and the second substrate, with the liquid crystal
material interposed therebetween; and (E) after step (D),
performing light irradiation to cure the sealant.
[0047] A still another liquid crystal display panel production
method according to the present invention is a method for producing
a liquid crystal display panel including a first substrate, a
second substrate, and a liquid crystal layer interposed between the
first substrate and the second substrate, the liquid crystal
display panel having a display region, a non-display region
surrounding the display region, and a broad-gap region within the
non-display region, the broad-gap region being a region in which a
gap between the first substrate and the second substrate is
partially increased, the broad-gap region comprising a dent in a
surface of the first substrate or the second substrate, the method
comprising the steps of: (A) providing the first substrate or a
first mother substrate containing the first substrate, and the
second substrate or a second mother substrate containing the second
substrate, wherein the first substrate includes a first light
shielding layer provided within the non-display region at an end
closer to the display region; (B) drawing a seal pattern by using a
sealant containing a photocurable resin, the seal pattern being
drawn outside the first light shielding layer of the first
substrate having the dent, or the seal pattern being drawn in a
region of the second substrate to be located outside the first
light shielding layer of the first substrate when the second
substrate having the dent is attached to the first substrate, the
seal pattern being drawn so as to surround the display region; (B')
applying a transfer material containing a photocurable resin to the
first substrate or the second substrate for forming a transfer
section for establishing electrical connection between the first
substrate and the second substrate, the transfer material being
applied in the dent; (C) applying a liquid crystal material within
the display region surrounded by the sealant; (D) attaching
together the first substrate and the second substrate, with the
liquid crystal material interposed therebetween; and (E) after step
(D), performing light irradiation to cure the sealant.
[0048] In one embodiment, step (B) comprises a substep of (B1)
beginning application of the sealant from the dent of the first
substrate or the second substrate.
[0049] In one embodiment, the liquid crystal display panel
production method further comprises a step of forming the dent,
wherein the step of forming the dent comprises a substep of forming
a throughhole or hole in a photosensitive resin layer of a positive
or negative type.
[0050] In one embodiment, the liquid crystal display panel
production method further comprises a step of forming the dent,
wherein the step of forming the dent comprises a substep of forming
a hole in the photosensitive resin layer by using a half exposure
technique.
[0051] In one embodiment, the first substrate includes a color
filter in the display region.
[0052] A liquid crystal display panel according to the present
invention is a liquid crystal display panel including a first
substrate, a second substrate, a liquid crystal layer interposed
between the first substrate and the second substrate, and a sealing
portion surrounding the liquid crystal layer, the liquid crystal
display panel having a display region and a non-display region
surrounding the display region, wherein, the first substrate
includes a first light shielding layer provided within the
non-display region at an end closer to the display region, the
first light shielding layer including at least one
light-transmitting portion provided near an outer boundary of the
first light shielding layer, the at least one light-transmitting
portion comprising a recess or an opening; and the sealing portion
has a broadened width at the at least one light-transmitting
portion.
[0053] Another liquid crystal display panel according to the
present invention is a liquid crystal display panel including a
first substrate, a second substrate, a liquid crystal layer
interposed between the first substrate and the second substrate, a
sealing portion surrounding the liquid crystal layer, and a
transfer section for establishing electrical connection between the
first substrate and the second substrate, the liquid crystal
display panel having a display region and a non-display region
surrounding the display region, wherein, the first substrate
includes a first light shielding layer provided within the
non-display region at an end closer to the display region, the
first light shielding layer including at least one
light-transmitting portion provided near an outer boundary of the
first light shielding layer, the at least one light-transmitting
portion comprising a recess or an opening; and at least a part of
the transfer section is provided in the at least one
light-transmitting portion.
[0054] In one embodiment, the first substrate includes a color
filter in the display region.
[0055] In one embodiment, the second substrate includes at least
one second light shielding layer in the non-display region, the at
least one second light shielding layer being provided in a region
corresponding to the at least one light-transmitting portion of the
first substrate.
[0056] In one embodiment, the second substrate includes a source
bus line and a gate bus line; and the at least one second light
shielding layer comprises a same conductive layer as that of the
source bus line or the gate bus line.
[0057] In one embodiment, the at least one light-transmitting
portion comprises slit-like recesses or openings; and the at least
one second light shielding layer includes a plurality of light
shielding portions provided so as to oppose the slit-like recesses
or openings.
[0058] A still another liquid crystal display panel according to
the present invention is a liquid crystal display panel including a
first substrate, a second substrate, a liquid crystal layer
interposed between the first substrate and the second substrate, a
sealing portion surrounding the liquid crystal layer, and a
transfer section for establishing electrical connection between the
first substrate and the second substrate, the liquid crystal
display panel having a display region and a non-display region
surrounding the display region, wherein, the liquid crystal display
panel includes a broad-gap region within the non-display region,
the broad-gap region being a region in which a gap between the
first substrate and the second substrate is partially increased,
the broad-gap region comprising a dent in a surface of the first
substrate or the second substrate; and the transfer section is
provided in the dent.
[0059] A still another liquid crystal display panel according to
the present invention is a liquid crystal display panel including a
first substrate, a second substrate, a liquid crystal layer
interposed between the first substrate and the second substrate,
and a sealing portion surrounding the liquid crystal layer, the
liquid crystal display panel having a display region and a
non-display region surrounding the display region, wherein, the
liquid crystal display panel includes a broad-gap region within the
non-display region, the broad-gap region being a region in which a
gap between the first substrate and the second substrate is
partially increased, the broad-gap region comprising a dent in a
surface of the first substrate or the second substrate; and a part
of the sealing portion is provided in the dent.
[0060] In one embodiment, the dent comprises a throughhole or hole
formed in a photosensitive resin layer of a positive or negative
type.
[0061] In accordance with a liquid crystal display panel production
method of the present invention, a substrate including a light
shielding layer which has a light-transmitting portion (recess or
opening) at a position to become a junction of a sealant is used,
and light irradiation is performed from the side of this substrate.
As a result, insufficient sealant curing at the junction is
prevented. Moreover, by providing a light-transmitting portion at a
corner portion or a transfer section (e.g., a common transfer
section) at which the width of the seal pattern is likely to become
broadened, curing failure of the sealant at such a corner portion
or transfer section can also be prevented. Thus, since a
light-transmitting portion is provided only in a portion(s) of the
light shielding layer at which the width of the seal pattern is
expected to become thick, the width of the non-display region can
be kept narrow. Furthermore, by providing a light shielding layer
on another substrate (at a position opposing the position at which
the light-transmitting portion is provided on the first substrate),
the original purpose of the light shielding layer, i.e., prevention
of light leakage, will not be undermined.
[0062] Since it is unnecessary to form a sealing portion outside
the liquid crystal display panel, failures during the cutting of
the mother substrate are prevented. Furthermore, by providing two
or more junctions in the liquid crystal display panel, an increased
freedom is obtained with respect to the drawing order of the seal
pattern, and/or it becomes possible to perform a simultaneous
drawing using a plurality of dispensers, whereby the tact time of
the seal drawing process can be reduced. By providing two or more
junctions in the seal pattern, it becomes possible to perform a
seal pattern drawing on the large-sized liquid crystal display
panel by using a relatively small seal pattern drawing apparatus,
whereby an increase in the production cost can be suppressed.
[0063] By using a color filter substrate as the aforementioned
substrate, damage to the TFTs due to UV can be reduced.
Furthermore, it becomes possible to omit a mask to be used for
protecting the TFTs in the light irradiation process. By performing
light irradiation also from the TFT substrate side, the irradiation
time required for the curing can be reduced.
[0064] In accordance with the liquid crystal display panel
production method of the present invention, a dent is provided in a
surface of the substrate at a portion at which the seal pattern is
expected to have a broadened width (e.g., a sealing junction or a
transfer section), the dent defining a region with a large gap
between the substrates. As a result, an increase in the seal
pattern width can itself be suppressed. By employing such a dent
together with the aforementioned light-transmitting portion, it
becomes possible to obtain both effects.
[0065] Other features, elements, processes, steps, characteristics
and advantages of the present invention will become more apparent
from the following detailed description of preferred embodiments of
the present invention with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0066] FIGS. 1A, 1B, 1C, and 1D are schematic illustrations showing
the structure of a sealing junction in a liquid crystal display
panel according to an embodiment of the present invention.
[0067] FIG. 2 is a schematic illustration for describing a seal
drawing process for a CF mother substrate 20 from which six color
filter substrates are obtained.
[0068] FIGS. 3A and 3B are schematic illustrations showing the
structure of a seal at a corner portion of a liquid crystal display
panel according to an embodiment of the present invention. FIG. 3A
is a plan view, and FIG. 3B is a cross-sectional view taken along
line 3B-3B' in FIG. 3A.
[0069] FIG. 4 is a plan view showing a typical liquid crystal
display panel.
[0070] FIGS. 5A to 5C are schematic illustrations showing an
exemplary structure of a light shielding layer in the case where a
light-transmitting portion is provided along a side on which no
signal line terminal section is provided. FIG. 5A is a plan view;
FIG. 5B is a cross-sectional view taken along line 5B-5B' in FIG.
5A; and FIG. 5C is a cross-sectional view taken along line 5C-5C'
in FIG. 5A.
[0071] FIGS. 6A to 6C are schematic illustrations showing another
exemplary structure of a light shielding layer in the case where a
light-transmitting portion is provided along a side on which no
signal line terminal section is provided. FIG. 6A is a plan view;
FIG. 6B is a cross-sectional view taken along line 6B-6B' in FIG.
6A; and FIG. 6C is a cross-sectional view taken along line 6C-6C'
in FIG. 6A.
[0072] FIGS. 7A to 7C are schematic illustrations showing still
another exemplary structure of a light shielding layer in the case
where a light-transmitting portion is provided along a side on
which no signal line terminal section is provided. FIG. 7A is a
plan view; FIG. 7B is a cross-sectional view taken along line
7B-7B' in FIG. 7A; and FIG. 7C is a cross-sectional view taken
along line 7C-7C' in FIG. 7A.
[0073] FIGS. 8A to 8D are schematic illustrations showing an
exemplary structure of a light shielding layer in the case where a
light-transmitting portion is provided in a region corresponding to
a gate bus line terminal section GB1 along a shorter side SE1 of a
liquid crystal display panel. FIG. 8A is a plan view; FIG. 8B is a
cross-sectional view taken along line 8B-8B' in FIG. 8A; FIG. 8C is
a cross-sectional view taken along line 8C-8C' in FIG. 8A; and FIG.
8D is a cross-sectional view taken along line 8D-8D' in FIG.
8A.
[0074] FIGS. 9A to 9D are schematic illustrations showing another
exemplary structure of a light shielding layer in the case where a
light-transmitting portion is provided in a region corresponding to
a gate bus line terminal section GB1 along a shorter side SE1 of a
liquid crystal display panel. FIG. 9A is a plan view; FIG. 9B is a
cross-sectional view taken along line 9B-9B' in FIG. 9A; FIG. 9C is
a cross-sectional view taken along line 9C-9C' in FIG. 9A; and FIG.
9D is a cross-sectional view taken along line 9D-9D' in FIG.
9A.
[0075] FIGS. 10A to 10C are schematic illustrations showing still
another exemplary structure of a light shielding layer in the case
where a light-transmitting portion is provided in a region
corresponding to a gate bus line terminal section GB1 along a
shorter side SE1 of a liquid crystal display panel. FIG. 10A is a
plan view; FIG. 10B is a cross-sectional view taken along line
10B-10B' in FIG. 10A; FIG. 10C is a cross-sectional view taken
along line 10C-10C' in FIG. 10A.
[0076] FIGS. 11A to 11D are schematic illustrations showing an
exemplary structure of a light shielding layer in the case where a
light-transmitting portion is provided in a region corresponding to
a source bus line terminal section SB1 along a longer side LE1 of a
liquid crystal display panel. FIG. 11A is a plan view; FIG. 11B is
a cross-sectional view taken along line 11B-11B' in FIG. 11A; FIG.
11C is a cross-sectional view taken along line 11C-11C' in FIG.
11A; and FIG. 11D is a cross-sectional view taken along line
11D-11D' in FIG. 11A.
[0077] FIGS. 12A to 12D are schematic illustrations showing another
exemplary structure of a light shielding layer in the case where a
light-transmitting portion is provided in a region corresponding to
a source bus line terminal section SB1 along a longer side LE1 of a
liquid crystal display panel. FIG. 12A is a plan view; FIG. 12B is
a cross-sectional view taken along line 12B-12B' in FIG. 12A; FIG.
12C is a cross-sectional view taken along line 12C-12C' in FIG.
12A; and FIG. 12D is a cross-sectional view taken along line
12D-12D' in FIG. 12A.
[0078] FIGS. 13A to 13C are schematic illustrations showing still
another exemplary structure of a light shielding layer In the case
where a light-transmitting portion is provided in a region
corresponding to a source bus line terminal section SB1 along a
longer side LE1 of a liquid crystal display panel. FIG. 13A is a
plan view; FIG. 13B is a cross-sectional view taken along line
13B-13B' in FIG. 13A; FIG. 13C is a cross-sectional view taken
along line 13C-13C' in FIG. 13A.
[0079] FIG. 14 is a schematic illustration showing a sealing
portion 32 and a light shielding layer 22 including a recess 22a in
a liquid crystal display panel according to an embodiment of the
present invention.
[0080] FIGS. 15A and 15B are schematic plan views for describing a
commonly-employed liquid crystal display panel arrangement.
[0081] FIGS. 16A, 16B, 16C, and 16D are schematic plan views
showing the structure of a conventional common transfer
section.
[0082] FIGS. 17A and 17B are schematic illustrations each showing
the structure of a common transfer section in a liquid crystal
display panel according to an embodiment of the present
invention.
[0083] FIGS. 18A, 188, 18C, and 180 are schematic illustrations
each showing the structure of a common transfer section in a liquid
crystal display panel according to an embodiment of the present
invention.
[0084] FIGS. 19A, 19B, 19C, and 19D are schematic illustrations
each showing the structure of a common transfer section in a liquid
crystal display panel according to another embodiment of the
present invention.
[0085] FIG. 20 is a graph showing a relationship between the
thickness of a resin layer 61 (depth of a throughhole 61a) and the
effect of reducing the width of the sealing portion 32.
[0086] FIG. 21 is a schematic illustration showing the
characteristics of a zeal pattern used in a one drop filling
technique.
[0087] FIGS. 22A and 22B are enlarged views showing the
neighborhood of a sealing junction FIG. 22A is a plan view, and
FIG. 22B is a cross-sectional view.
[0088] FIG. 23 is a schematic illustration showing an example of a
conventional seal pattern.
[0089] FIG. 24 is a schematic illustration showing another example
of a conventional seal pattern.
[0090] FIGS. 25A and 25B are schematic illustrations for describing
a problem of conventional seal patterns.
[0091] FIGS. 26A and 26B are schematic illustrations for describing
another problem of conventional seal patterns.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0092] Hereinafter, a liquid crystal display panel according to an
embodiment of the present invention and a method for producing the
same will be described, with reference to the accompanying
drawings.
[0093] As shown in FIGS. 1A and 1B, a liquid crystal display panel
according to an embodiment of the present invention includes: a TFT
substrate 10, a color filter substrate 20, a liquid crystal layer
40 provided between the TFT substrate 10 and the color filter
substrate 20, and a sealing portion 32 surrounding the liquid
crystal layer 40. The liquid crystal display panel has a display
region and a non-display region surrounding the display region. The
color filter substrate 20 has a first light shielding layer 22A,
which is provided within the non-display region, at an end closer
to the display region. The first light shielding layer 22A has a
recess (light-transmitting portion) 22a provided near the outer
boundary. The width of the sealing portion 32 is allowed to become
wider at the recess 22a of the light shielding layer 22A. Granted
that the recess 22a of the light shielding layer 22A has a
sufficient width and length, if a junction 32b is formed in the
recess 22a, the junction 32b will not overlap the light shielding
layer 22A even when the junction 32b has an increased width.
Therefore, as shown in FIG. 1B, the sealant can be sufficiently
cured even if UV irradiation is performed from the rear face side
of the color filter substrate 20.
[0094] Note that the sealant is not limited to a UV curable resin,
but may be a resin which is cured with light of any other
wavelength (e.g., visible light), and various photocurable resins
can be suitable. As used herein, a "photocurable resin" refers to
any resin which undergoes curing reaction in response to
irradiation of light of a predetermined wavelength, and includes
any resin for which thermosetting can be further performed after
photocuring. With such auxiliary use of thermosetting, the physical
characteristics of the cured matter (e.g., hardness and elastic
modulus) are generally improved. Furthermore, particles (filler)
for conferring a scattering ability to the sealant may be mixed to
the sealant together with the photocurable resin. A sealant in
which particles are dispersed will cause scattering or diffuse
reflection of light, thus allowing light to be permeated through a
broader region of the sealant.
[0095] The light shielding layer 22A of the color filter substrate
20 shown in FIG. 1A is illustrated as having a single recess 22a
which extends over the entire length of the junction 32b. Instead
of such a recess 22a, any other recess may be used as long as the
recess allows the sealant to be sufficiently irradiated with light.
For example, as exemplified by a light shielding layer 22B shown in
FIG. 1C, a plurality of minute recesses 22b may be provided in
stripes. Alternatively, as exemplified by a light shielding layer
22C shown in FIG. 1D, a plurality of minute openings (holes) 22c
may be provided. Depending on the recess(es) or the opening(s), the
light-transmitting portion for allowing the sealant to receive
light irradiation does not need to be formed with a constant width,
but may have a changing width so as to accommodate the expanding
width of the junction 32 as necessary. In the case where the
recesses 22b or openings 22c as shown in FIG. 1C or 1D are
provided, it is more difficult for the sealant to receive light
irradiation than in the case of employing the recess 22a shown in
FIG. 1A. Therefore, in this case, it would be preferable to employ
a light irradiation apparatus of a type which not only allows light
to be incident to the substrate at a right angle but can also
introduce a certain irradiation angle by means of a reflector or
the like, or employ a sealant which has scattering abilities
(diffuse reflection properties).
[0096] In the final liquid crystal display panel, the display
quality may be deteriorated due to the light which has passed
through the recess 22a provided in the light shielding layer 22A.
Therefore, it is preferable to provide a further light shielding
layer in a position opposing the recess 22a. Although it might be
possible to attach a light shielding tape or the like on the
outside (i.e., the side closer to the viewer) of the color filter
substrate 20, such is not preferable because the number of
production steps will be increased, positioning problems may occur,
and a level difference may occur when the liquid crystal display
panel is mounted in a housing. Therefore, as will be later
described in specific examples, it is preferable to provide a light
shielding layer at a corresponding position on the TFT substrate
10. In this case, by forming a light shielding layer by using the
same conductive layer as that of the source bus line and/or gate
bus line provided on the TFT substrate, it becomes possible to form
the light shielding layer without increasing the number of
steps.
[0097] By adopting the above-described structure, it becomes
possible to allow the sealant to be sufficiently cured even if a
sealing junction is formed within the liquid crystal display panel,
without complicating the production steps. It is also possible to
effectively prevent leakage of light from a light-transmitting
portion which is provided in a light shielding layer of a color
filter substrate. Since light irradiation is performed from the
color filter substrate side, the light with which the TFTs are
irradiated is attenuated at least when transmitted through, the
color filters, so that damage due to light irradiation for the TFTs
can be reduced. In the case where it is possible to obtain a
sufficient attenuation with the color filters alone, it is
unnecessary to employ a mask for protecting the TFTs from light
irradiation, thus further improving the production efficiency.
[0098] Next, with reference to FIG. 2, a liquid crystal display
panel according to an embodiment of the present invention
production method will be described.
[0099] FIG. 2 is a schematic illustration for describing a seal
drawing process for a CF mother substrate 20 from which six color
filter substrates are obtained. One advantage of a liquid crystal
display panel according to an embodiment of the present invention
production method is that, as will be described below, use of a
plurality of junctions makes it possible to obtain a large-sized
liquid crystal display panel by using a dispenser which in itself
has a relatively narrow movable range. Another advantage is that,
by providing two or more junctions within the liquid crystal
display panel, an increased freedom is obtained with respect to the
drawing order of the seal pattern, and/or it is possible to
simultaneously draw the seal pattern by employing a plurality of
dispensers, whereby the tact time of the seal drawing process can
be reduced.
[0100] For one of the six color filter substrates 20 (A1 to A3 and
B1 to B3) to be derived from the CF mother substrate 20 (e.g., A1
in FIG. 2), application of a sealant may be begun from a point S1,
for example. Thus, the point S1 serves as a start point of the seal
pattern. The point S1 is chosen in the neighborhood of the recess
22a of the color filter substrate 20 (note that FIG. 2
schematically illustrates the recesses 22a only). After seal
drawing is begun from the point S1, the sealant is applied along
the outer periphery of the light shielding layer 22 of the color
filter substrate 20 (along the solid line in FIG. 2), and the
sealant application is ended in the neighborhood (point S2) of
another recess 22a. The point S2 serves as an end point of the seal
pattern.
[0101] Thereafter, with respect to the color filter substrate A1,
sealant application is again begun from the start point S1, and,
along the broken line in FIG. 2, seal drawing is performed until
reaching the end point S2. Thus, a sealing portion which surrounds
the display region can be formed.
[0102] Thus, by adopting a constitution in which a plurality of
junctions are provided, it becomes unnecessary to encompass the
entire range from the start point S1 to the end point S1 in a
single drawing. Therefore, seal drawing is enabled even if the
nozzle of the dispenser (and/or the mother substrate) can only move
in a relatively narrow movable range. In the case where a
sufficient movable range is available, it would off course be
possible to begin seal drawing from e.g. the start point S1, apply
the sealant along the outer periphery of the light shielding layer
22 of the color filter substrate 20, past the point S2 and then
back to the start point S1, thus forming a junction at the point
S1. In this case, only one junction will be formed at the point
S1.
[0103] Furthermore, according to the production method of the
embodiment of the present invention, it is not necessary to
complete the entire sealing portion 32 on one of the six color
filter substrates (A1 to A3 and B1 to B3) before moving onto
another color filter substrate. For example, a seal pattern
corresponding to the solid line may be simultaneously drawn on each
of the color filter substrates A1 to A3; and subsequently to or
concurrently with this, a seal pattern corresponding to the solid
line may be simultaneously drawn on each of the color filter
substrates B1 to B3. Thereafter, a seal pattern corresponding to
the broken line may be simultaneously drawn on each of the color
filter substrates A1 to A3; and subsequently to or concurrently
with this, a seal pattern corresponding to the broken line may be
simultaneously drawn on each of the color filter substrates B1 to
B3.
[0104] Although this example illustrates the case where the
recesses 22a are provided on the shorter sides of the substrate
having a rectangular shape, it would also be possible to provide a
recess(es) on a longer side(s) of the substrate. Furthermore, it
would also be possible to provide recesses on both a shorter
side(s) and a longer side(s), thus forming three or more junctions.
The positioning of the recesses 22a (i.e., the light-transmitting
portions) may be adjusted according to the movable range of the
dispenser, the size of the mother substrate, and the positioning of
the panels in the mother substrate. Without being limited to the
recesses 22a, it may be possible to employ recesses 22b or openings
22c as shown in FIG. 1C or 1D, or any mixture thereof. Thus, there
are no limitations as to the shape of the recesses or openings as
long as the sealant is sufficiently irradiated with light. However,
as will be described later, it would be preferable to optimize the
shapes and positioning of the recesses or openings in order to
realize efficient light shielding with the light shielding layer
provided on the TFT substrate.
[0105] Although the above example illustrates a case where seal
drawing is performed for the CF mother substrate 20, it would also
be possible to draw a seal pattern in a corresponding region of the
TFT mother substrate 10. In other words, a seal pattern may drawn
so that the position at which the sealing portion 32 will be formed
when the color filter substrate 20 and the TFT substrate 10 are
attached together satisfies the aforementioned relationship with
respect to the light-transmitting portion(s) 22 (recesses 22a) in
the light shielding layer 22 of the color filter substrate.
[0106] In the liquid crystal display panel production method of the
present embodiment, the junction of the sealant is formed inside
the liquid crystal display panel, and therefore, no sealing portion
exists outside the liquid crystal display panel, unlike in Japanese
Laid-Open Patent Publication No. 2002-122870. As a result, cutting
failures are prevented when the TFT mother substrate 10 and the CF
mother substrate 20 are cut into pieces corresponding to liquid
crystal panels. Even in the case where signal line terminal
sections are to be provided on three or more sides of the liquid
crystal panel, problems such as inability to remove a fragment of
the color filter substrate are prevented.
[0107] Note that light-transmitting portions such as the recesses
22 are preferably provided not only at junctions but also at corner
portions, as shown in FIGS. 3A and 3B. By providing a recess 22d in
a corner portion of a light shielding layer 22D, it becomes
possible to prevent a sealant 32a' which has become thick at the
corner portion from overlapping the light shielding layer 22D, thus
allowing the sealant to be sufficiently cured.
[0108] Although a junction might well be formed at such a corner
portion, it is preferable to form any junction along a side
(excluding the corners) of the substrate, from the standpoint of
facilitating examination of the junction. A junction which is
formed along a side can be tested for soundness by detecting the
width of the sealing portion by using an optical technique. In
other words, failures such as incompleteness (i.e., disruption) or
excessively thin width of a junction can be easily detected if the
junction is formed along a side.
[0109] Next, with reference to FIGS. 4 to 13, the structure of a
liquid crystal display panel according to an embodiment of the
present invention will be described in more detail.
[0110] FIG. 4 is a plan view showing a typical liquid crystal
display panel. The liquid crystal display panel includes: a TFT
substrate 10'; a color filter substrate 20; and a sealing portion
32 for realizing adhesive attachment between the TFT substrate 10'
and the color filter substrate 20. The TFT substrate 10' has two
longer sides LE1 and LE2, as well as two shorter sides SE1 and SE2.
In the example shown, the longer side LE1 and the shorter side SE1
extend outside the color filter substrate 20; a source bus line
terminal section SB1 is provided on the longer side LE1; and a gate
bus line terminal section GB1 is provided on the shorter side SE1.
Therefore, at these signal bus line terminal sections SB1 and GB1,
the sealing portion 32 and a light shielding portion (not shown) of
the color filter substrate 20 overlap the signal bus lines.
Therefore, in the case where the TFT substrate needs to have a
light shielding layer corresponding to the light-transmitting
portions (e.g., recesses) which are provided in the light shielding
layer of the color filter substrate 20, the preferable structure of
such light shielding layer would vary depending on the positions of
the lines (e.g., the source bus lines or the gate bus lines).
[0111] FIG. 4 illustrates an example where signal line terminal
sections are provided on two sides of the substrate. Alternatively,
the present invention is also applicable to a structure featuring
signal line terminal sections provided on three sides (e.g., gate
bus line terminal sections being provided on the two shorter
sides), or a structure featuring signal line terminal sections
provided on four sides (i.e., gate bus line terminal sections being
provided on two sides and source bus line terminal sections being
provided on the other two sides).
[0112] First, with reference to FIGS. 5A, 5B, 5C, 6A, 6B, 6C, 7A,
7B, and 7C, an exemplary structure of a light shielding layer in
the case where a light-transmitting portion is provided along sides
(SE2 or LE2) on which no signal line terminal section is provided
will be described. FIGS. 5A to 5C are illustrations showing an
exemplary structure of a light shielding layer in the case where a
light-transmitting portion is provided along a side on which no
signal line terminal section is provided. FIG. 5A is a plan view;
FIG. 5B is a cross-sectional view taken along line 5B-5B' in FIG.
5A; and FIG. 5C is a cross-sectional view taken along line 5C-5C'
in FIG. 5A. FIGS. 6A to 6C are illustrations showing another
exemplary structure. FIG. 6A is a plan view; FIG. 6B is a
cross-sectional view taken along line 6B-6B' in FIG. 6A; and FIG.
6C is a cross-sectional view taken along line 6C-6C' in FIG. 6A.
FIGS. 7A to 7C are illustrations showing still another exemplary
structure. FIG. 7A is a plan view; FIG. 7B is a cross-sectional
view taken along line 7B-7B' in FIG. 7A; and FIG. 7C is a
cross-sectional view taken along line 7C-7C' in FIG. 7A.
[0113] FIGS. 5A to 5C illustrate a case where a recess 22a is
provided at a position where a sealing junction 32b is to be
formed. FIGS. 6A to 6C illustrate a case where a plurality of
recesses 22b are provided at such a position. FIGS. 7A to 7C
illustrate a case where a plurality of recesses 22b' and a
plurality of openings 220' are provided at such a position. In
either case, no gate bus line terminal section or no source bus
line terminal section exists in the regions of the TFT substrate 10
corresponding to the light-transmitting portions (22a, 22b, 22b',
22c') in the light shielding layer 22 of the color filter
substrate. Therefore, a light shielding layer 12a may be provided
in any necessary regions. The TFT substrate 10 includes a glass
substrate 11, gate bus lines (not shown) formed on the glass
substrate 11, a gate insulating film 13 covering the gate bus
lines, source bus lines (not shown) formed on the gate insulating
film, and an insulative protection film 15 covering the source bus
lines. When patterning the conductive layer composing the gate bus
lines, the patterning may be performed in such a manner as to leave
the light shielding layer 12a intact, thus allowing the light
shielding layer 12a to be formed through the same process of
forming the gate bus lines. By adopting such a constitution, it
becomes possible to form the light shielding layer 12a on the TFT
substrate 10 without increasing the number of production steps.
[0114] On the shorter side SE2, main lines of storage capacitor
line for supplying predetermined signals for storage capacitors
which are provided for the respective pixels, and reserve lines for
correcting electrical connections of any signal line that has
experienced a break. Such main or reserve lines are relatively
thick, and therefore can be utilized as a light shielding layer. In
general, main lines and reserve lines of storage capacitor line are
composed of the same conductive layer that composes the gate bus
lines, and are formed by the same process of forming the gate bus
lines. Thus, since a high design freedom for forming the light
shielding layer exists at the shorter sides of the liquid crystal
display panel, it is preferable to form any sealing junction on a
shorter side.
[0115] Specifically, the TFT substrate can be fabricated through
the following process.
[0116] On the glass substrate 11, a Ti/Al/TiN stacked film is grown
by using a sputtering apparatus. Through etching processes such as
a photolithography process and dry etching, the gate bus lines and
the gate electrodes are formed, and the light shielding layer 12a
is also concurrently formed. For example, in the case where storage
capacitor line is to be formed concurrently with the gate bus lines
and the like, the main lines of storage capacitor line may be
provided at the shorter side SE2, thus making it possible to
utilize the main lines of storage capacitor line as the light
shielding layer 12a.
[0117] Next, upon these layers, the gate insulating film 13 of
silicon nitride (SiNx) or the like is grown by a plasma CVD
technique. Thereafter, active elements such as TFTs are formed.
Furthermore, a Ti/Al/TiN stacked film is grown by using a
sputtering apparatus, and through etching processes such as a
photolithography process and dry etching, the source bus lines and
the drain electrodes are formed.
[0118] Next, an insulative protection film 15 such as a transparent
resin is formed by a spin coating technique or the like. In the
insulative protection film 15, contact holes for establishing
contact between the pixel electrodes to be formed thereupon and the
drain electrodes are made, and throughholes for forming storage
capacitors are made. Upon the insulative protection film 15,
transparent electrodes (e.g., ITO) are grown by sputtering, and the
pixel electrodes are formed through a photolithography process and
an etching process.
[0119] The color filter substrate may be fabricated as follows, for
example.
[0120] By a dry film technique, a spin coating technique, an ink
jet technique or the like, a light shielding layer is formed in
regions of a glass substrate 21 corresponding to color filters of
RGB (red, green, blue) which correspond to the pixels of the TFT
substrate, as well as other necessary regions. Since the light
shielding layer is formed by using a black photocurable resin,
light-transmitting portions (recesses and/or openings) can be
formed through the same process during patterning.
[0121] Next, with reference to FIGS. 8A, 8B, 8C, 8D, 9A, 9B, 9C,
9D, 10A, 10B, and 10C, an exemplary structure of a light shielding
layer in the case where light-transmitting portions are to be
provided in a region corresponding to the gate bus line terminal
section GB1 along the shorter side SE1 will be described. FIGS. 8A
to 8C are illustrations showing an exemplary structure of a light
shielding layer in the case where light-transmitting portions are
to be provided in a region corresponding to the gate bus line
terminal section GB1 along the shorter side SE1. FIG. 8A is a plan
view; FIG. 8B is a cross-sectional view taken along line 8B-8B' in
FIG. 8A; FIG. 8C is a cross-sectional view taken along line 8C-8C'
in FIG. 8A; and FIG. 8D is a cross-sectional view taken along line
8D-8D' in FIG. 8A: FIGS. 9A to 9C are illustrations showing another
exemplary structure. FIG. 9A is a plan view; FIG. 9B is a
cross-sectional view taken along line 9B-9B' in FIG. 9A; FIG. 9C is
a cross-sectional view taken along line 9C-9C' in FIG. 9A; and FIG.
9D is a cross-sectional view taken along line 9D-9D' in FIG. 9A.
FIGS. 10A to 10C are illustrations showing still another exemplary
structure. FIG. 10A is a plan view; FIG. 10B is a cross-sectional
view taken along line 10B-10B' in FIG. 10A; and FIG. 10C is a
cross-sectional view taken along line 10C-10C' in FIG. 10A.
[0122] Gate bus lines 12b are formed on the glass substrate 11 of
the TFT substrate 10. The gate bus lines 12b function as a light
shielding layer. However, in the case where a recess 22a is formed
as shown in FIG. 8A, light will pass through between the gate bus
lines 12b. Therefore, a conductive layer 14a which is in the same
layer level as the source bus lines is used to form a plurality of
light shielding portions 14a for ensuring light shielding in the
interspaces between the gate bus lines 12b, as shown in FIG. 8D. It
might be possible to construct the light shielding portions 14a in
the form of a single light shielding layer which overlaps the gate
bus lines 12b and any interspaces therebetween. However, in the
case where such a light shielding layer overlaps with the gate bus
lines via the gate insulating film 13, there may be a possible
problem of insufficient insulation due to foreign matter or the
like, and in some cases, short-circuiting may occur between the
gate bus lines. Therefore, from the standpoint of production yield,
it would be preferable to form discrete light shielding portions
14a corresponding to the interspaces between the gate bus lines
12b, so that there is no overlap between the resultant light
shielding layer and the gate bus lines 12b.
[0123] As shown in FIG. 9A, a plurality of recesses 22b may be
provided so as to oppose the gate bus lines 12b. In this case,
sufficient light shielding can be realized with the gate bus lines
12b alone, and thus an advantage of a simplified construction is
provided.
[0124] As shown in FIG. 10A, a plurality of recesses 22b' and a
plurality of openings 22c' may be provided such that the openings
22c' oppose the gate bus lines 12b, and a light shielding layer 14a
may be provided so as to correspond to the recesses 22b'. As a
result, light passing through the light-transmitting portions can
be shielded.
[0125] Next, with reference to FIGS. 11A, 11B, 11C, 11D, 12A, 12B,
12C, 12D, 13A, 13B, and 13C, an exemplary structure of a light
shielding layer in the case where light-transmitting portions are
to be provided in a region corresponding to the source bus line
terminal section SB1 along the longer side LE1 will be
described.
[0126] FIGS. 11A to 11C are illustrations showing an exemplary
structure of a light shielding layer in the case where
light-transmitting portions are to be provided in a region
corresponding to the source bus line terminal section SB1 along the
longer side LE1. FIG. 11A is a plan view; FIG. 11B is a
cross-sectional view taken along line 11B-11B' in FIG. 11A; FIG.
11C is a cross-sectional view taken along line 11C-11C' in FIG.
11A; and FIG. 11D is a cross-sectional view taken along line
11D-11D' in FIG. 11A. FIGS. 12A to 12C are illustrations showing
another exemplary structure. FIG. 12A is a plan view; FIG. 12B is a
cross-sectional view taken along line 12B-12B' in FIG. 12A; FIG.
12C is a cross-sectional view taken along line 12C-12C' in FIG.
12A; and FIG. 12D is a cross-sectional view taken along line
12D-12D' in FIG. 12A. FIGS. 13A to 13C are illustrations showing
still another exemplary structure. FIG. 13A is a plan view; FIG.
13B is a cross-sectional view taken along line 13B-13B' in FIG.
13A; and FIG. 13C is a cross-sectional view taken along line
13C-13C' in FIG. 13A.
[0127] Source bus lines 14b are formed on the glass substrate 11 of
the TFT substrate 10. The source bus lines 14b function as a light
shielding layer. However, in the case where a recess 22a is formed
as shown in FIG. 11A, light will pass through between the source
bus lines 14b. Therefore, a conductive layer 12a which is in the
same layer level as the gate bus lines 12b is used to form a
plurality of light shielding portions 12a for ensuring light
shielding in the interspaces between the source bus lines 14b, as
shown in FIG. 11D. It might be possible to construct the light
shielding portions 12a in the form of a single light shielding
layer which overlaps the source bus lines 14b and any interspaces
therebetween. However, for the aforementioned reason, from the
standpoint of production yield, it would be preferable to form
discrete light shielding portions 12a corresponding to the
interspaces between the source bus lines 14b. Although FIG. 11D
illustrates an example where light shielding portions 12a are
formed under the gate insulating film 13, and the source bus lines
14b are formed on a gate insulating film, such is not the only
possible structure. For example, depending on the formation process
of the TFTs, there may be cases where the source bus lines in the
active area (display region) are connected to gate metals (i.e.,
conductive layers composing the gate bus lines) before being
connected to the source terminal portion in the frame region, thus
realizing the line in the source terminal portion by means of the
gate metals. In this case, the aforementioned effects will still be
obtained, although the stacking relationship (i.e., which one lies
above the other) between the lines 14b and the light shielding
portions 12a relative to the gate insulating film 13 will be
reversed from that shown in FIG. 11D. The same is also true of any
other embodiment.
[0128] As shown in FIG. 12A, a plurality of recesses 22b may be
provided so as to oppose the source bus lines 14b. In this case,
sufficient light shielding can be realized with the source bus
lines 14b alone, and thus an advantage of a simplified construction
is provided.
[0129] As shown in FIG. 13A, a plurality of recesses 22b' and a
plurality of openings 22c' may be provided such that the openings
22c' oppose the source bus lines 14b, and a light shielding layer
12a may be provided so as to correspond to the recesses 22b'. As a
result, light passing through the light-transmitting portions can
be shielded.
[0130] In the case where a 17'' SXGA type liquid crystal display
panel is to be produced by using a liquid crystal display panel
according to an embodiment of the present invention production
method, for example, the following structure may be preferable.
[0131] FIG. 14 is a schematic illustration showing a sealing
portion 32 and a light shielding layer 22 including a recess 22a in
a 17'' SXGA type liquid crystal display panel.
[0132] As shown in FIG. 14, the structure having a recess 22a as
shown in FIG. 1 is adopted in this example. The liquid crystal
display panel has the same structure as that shown in FIG. 4, with
the recess 22a being provided on the shorter side SE2. Main lines
of storage capacitor line provided on the TFT substrate are
utilized for light shielding within the recess 22a.
[0133] The interspace Ws between the perimeter of the light
shielding layer 22A and the cut line is 2.3 mm. The recess 22a has
a "depth" D of 0.3 mm and a length W of 10.0 mm. The width of the
light shielding layer 22A (in the region other than the recess 22a)
is about 3 mm. The reason for such sizing is described below.
[0134] It was found that, when a seal width (i.e., the width of the
main stretch 32a) of 1.2 mm was set on the particular dispenser
used, variations of .+-.0.3 mm would result. The positioning
accuracy of the nozzle of the dispenser was .+-.0.15 mm. A margin
of .+-. about 0.2 mm was determined based on the cutting accuracy
of the mother substrate. Therefore, the interspace Ws from the
perimeter of the light shielding layer 22A to the cut line must be
2 mm or more, based on 1.2 mm+0.3 mm+(0.15 mm.times.2)+0.2 mm. In
this particular example, Ws was set at 2.3 mm.
[0135] The width of the sealing junction 32b had a maximum value
Smax of about 2.1 mm. To this, the positioning accuracy (0.15
mm.times.2) of the nozzle was added, and further in view of the
cutting margin of 0.2 mm, the interspace from the perimeter of the
light shielding layer 22A to the cut line, at the recess 22a was
set to be 2.6 mm. In other words, the "depth" D of the recess 22a
was set at 0.3 mm.
[0136] Moreover, since any corner portion would become thicker than
the main stretch by 0.1 mm to 0.15 mm, the light shielding layer
was recessed by a "depth" of 0.15 mm at every corner portion, and a
seal pattern was drawn so that the minimum interspace between the
perimeter of the light shielding layer and the cut line was equal
to 2.45 mm (see FIG. 3A).
[0137] In the fabrication of the liquid crystal display panel, as
has been described with reference to FIG. 2, a seal drawing was
performed for the CF mother substrate 20. Thereafter, by a known
method, a liquid crystal material was dripped onto the CF mother
substrate 20 by a one drop filling technique. After the TFT mother
substrate 10 was attached thereto in a predetermined place, UV
irradiation was performed from the color filter substrate side to
cure the sealant. The sealant curing was supplemented by, after
performing UV irradiation at several joule/cm.sup.2, also
performing thermosetting at 120.degree. C. for 1 hour.
[0138] The resultant liquid crystal display panel experienced no
cutting failures during cutting, and no deterioration in
reliability was observed, e.g., lowering of the voltage retention
rate due to curing failure of the sealant, or orientation defects.
Moreover, no degradation in display quality due to light leakage
through the recess was observed.
[0139] By adopting the procedure which involves dripping a liquid
crystal material onto the CF mother substrate 20, attaching the TFT
mother substrate 10, and performing light irradiation from below
(i.e., from the CF mother substrate 20 side), it becomes possible
to perform all the steps from the seal drawing to the light
irradiation while maintaining the CF mother substrate 20 so as to
be on the lower side of the display panel (with the surface bearing
the color filters facing up), thus making it possible to use simple
apparatuses and processes.
[0140] With the patterns shown in FIGS. 1C and 1D, when light
irradiation for curing the sealant is performed only from the side
of one of the substrates, the irradiation time required for
achieving sufficient curing may be prolonged (occasionally
threefold or more) depending on the area ratio of the
light-transmitting portions.
[0141] On the other hand, the above-described structure featuring a
plurality of recesses or openings provided in the light shielding
layer of the CF substrate, where source bus lines and/or gate bus
lines, etc., are utilized as a light shielding layer of the TFT
substrate for selectively shielding the light passing through the
recesses or openings, makes it possible to perform light
irradiation for the sealant also from the TFT substrate side
because light is allowed to pass through the interspaces between
the source bus lines and/or the gate bus lines. Thus, it becomes
possible to perform light irradiation for the sealant from the
sides of both substrates, by ensuring that the light shielding
layer on the TFT substrate side includes light-transmitting
portions corresponding to the interspaces between, or the
peripheries around, the plurality of recesses or openings in the
light shielding layer of the CF substrate. As a result, the
irradiation time required for sealant curing can be reduced.
[0142] As a method for performing light irradiation from both sides
of the display panel, light sources may simply be provided above
and below the display panel, respectively. Alternatively, a
mechanism for reversing the display panel may be provided for the
apparatus used; in this case, the light irradiation time will be
about twice the minimum irradiation time required in the case of
performing irradiation from both sides of the display panel, but
will still be shorter than the irradiation time required in the
case of performing irradiation from only one side of the display
panel. Some sealing materials are capable of being photocured over
a distance of about several tens of .mu.m from the edge of each
opening toward the light shielding portion, and therefore it is
preferable to use such materials.
[0143] The pattern of recesses or openings is not limited to
stripes, but may also be a mesh pattern as shown in FIG. 1D.
Although FIG. 1D illustrates a mesh array consisting of circular
openings, the shape of the openings is not limited to circles, but
may be rectangular, for example. A part of the pattern may be
rounded or include a bent. In particular, in the case where light
shielding is realized by the signal lines on the TFT substrate, it
is likely that the shapes of the signal lines are subject to design
constraints. Therefore, it would be preferable to adapt the opening
pattern to the line pattern.
[0144] As light irradiation apparatuses for use in seal curing,
there are known apparatuses which employ a reflector and the like
to enable light irradiation in not only the normal direction of the
display panel, but also in an oblique direction. By employing such
an apparatus which is capable of performing light irradiation also
from an oblique direction, it becomes possible to attain sufficient
curing of the sealant even if there is a slight overlap between the
light shielding layer of the CF substrate and the light shielding
layer of the TFT substrate. For example, it has been experimentally
confirmed that, even if there is an overlap which is about as large
as the gap between the substrates, the resultant liquid crystal
display panel exhibits no significant difference in reliability
after being irradiated under the same irradiation conditions
(irradiation intensity and irradiation time) as those under the
case where there is no overlap.
[0145] Next, a problem that may occur in a transfer section (i.e.,
a section at which an electrical potential of an electrode on one
of the substrates is to be transferred to an electrode on the other
substrate which includes a terminal for providing connection to the
outside) will be described. Hereinafter, an example problem will be
illustrated with respect to a common transfer section, which is a
type of transfer section which composes a path for electrically
connecting a counter electrode (which is also referred to as a
"common electrode") on a CF substrate to a terminal on the TFT
substrate.
[0146] FIGS. 15A and 15B schematically show a commonly-employed TFT
liquid crystal display panel arrangement. FIG. 15B shows an
equivalent circuit of a single pixel of a TFT liquid crystal
display panel.
[0147] As shown in FIG. 15B, by driving a TFT 64 with a gate bus
line 63, with a source bus line 62 being connected to the TFT 64, a
predetermined signal voltage is supplied to a pixel electrode 65.
The pixel electrode 65 opposes a common electrode 66 with a liquid
crystal layer 40 interposed therebetween, thus constituting a
liquid crystal capacitance (capacitor). When a signal voltage is
applied across the liquid crystal layer 40 via the TFT 64, the
optical characteristics of the liquid crystal layer 40 are changed,
whereby the display panel functions as a display device.
[0148] The common electrode 66, which is formed on the surface of
the CF substrate 20 facing the liquid crystal layer 40, has its
electrical potential transferred to the TFT substrate 10' side via
a common transfer section 60, and thus is connected to a common
electrode terminal 66a. As shown in FIG. 15A, source bus lines 62a
and gate bus line terminals 63a are provided in the non-display
region of the TFT substrate 10'. Usually, the common electrode
terminals 66a and the source bus lines 62a are to be provided on
the same side (i.e., one of the four sides) of the display
panel.
[0149] As a transfer material composing the common transfer
section, a transfer material containing a photocurable resin and
conductive particles is used. The conductive particles may be, for
example, metal particles or plastic beads having a metal coating
thereon, with a grain size of about 4 to 10 .mu.m. As the
photocurable resin to be contained in the transfer material, any
photocurable resin similar to those used in a sealant is used.
[0150] In the case where a common transfer section is to formed by
using a transfer material containing a photocurable resin, the
frame region would need to be broad enough to provide a
light-transmitting region for allowing the common transfer section
to be irradiated with light. Therefore, each common transfer
section may be made to at least partially overlap with the sealing
portion. However, even if each common transfer section were to be
formed within the sealing portion, the width of the sealing portion
would become thicker where the sealing portion contains the common
transfer section, again resulting in the problem of a large frame
region.
[0151] This problem will be described with reference to FIGS. 16A
to 16D below. Any constituent element which also appears in the
foregoing descriptions will be denoted by like numerals, and their
descriptions will be omitted herein.
[0152] The common transfer section 60 is provided In the
neighborhood of the sealing portion 32, so as to electrically
connect a counter electrode (not shown) on a CF substrate (not
shown) to a common pad 60a on the TFT substrate. As shown in FIG.
16D, if the common transfer section 60 is provided at a position
away from the sealing portion 32, the non-display region (frame
region) must have a broad width. Therefore, as shown in FIGS. 16A
to 16C, it is common practice to allow the common transfer section
60 to at least partially overlap with the sealing portion 32.
However, in any of the cases illustrated in FIGS. 16A to 16C, the
sealant will be pushed out by the common transfer section 60, thus
resulting in a portion 32c (which may also be referred to as a
"common transfer sealing portion") at which the width of the seal
pattern is broadened. Thus, there is a problem in that the common
transfer sealing portion 32c has a broader width than that of the
main stretch 32a (see, for example, FIG. 1), similarly to the
above-described junction 32b.
[0153] Therefore, according to the present embodiment,
light-transmitting portions (recesses or openings) are provided in
the light shielding portion of the substrate from which the light
irradiation for curing the common transfer sealing portion 32c is
to be performed.
[0154] FIGS. 17A and 17B are schematic illustrations each showing
the structure of a common transfer section in a liquid crystal
display panel according to an embodiment of the present invention.
FIG. 17A is a plan view; and FIG. 17B is a cross-sectional view
taken along line 17B-17B' in FIG. 17A.
[0155] The color filter substrate 20 includes a first light
shielding layer 22A which is provided within the non-display
region, at an end closer to the display region. The first light
shielding layer 22A includes a recess (light-transmitting portion)
22a provided near the outer boundary. The width of the sealing
portion 32 is allowed to become wider at the recess 22a of the
light shielding layer 22A. Granted that the recess 22a of the light
shielding layer 22A has a sufficient width and length, if a common
transfer sealing portion 32c is formed in the recess 22a, the
common transfer sealing portion 320 will not overlap the light
shielding layer 22A even when the common transfer sealing portion
32c has an increased width. Therefore, as shown in FIG. 17B, the
sealant can be sufficiently cured even if UV irradiation is
performed from the rear face side of the color filter substrate 20.
So long as the sealant is subjected to sufficient light
irradiation, the light-transmitting portion is not limited to the
recess 22a. For example, as in the light shielding layer 22B shown
in FIG. 1C, stripes containing a plurality of minute recesses 22b
may be provided. Alternatively, as in the light shielding layer 22C
shown in FIG. 1D, a plurality of minute openings (holes) 22c may be
provided, or any other shape may be adopted, as in the
earlier-described embodiments.
[0156] Next, an embodiment in which the broadening of the width of
the sealing portion is in itself suppressed will be described. In
the embodiment described below, a broad-gap region, i.e., a region
in which the gap between the CF substrate and the TFT substrate is
partially increased, is provided within the non-display region of
the liquid crystal display panel. Any portion where the width of
the seal pattern is expected to increase is formed in this
broad-gap region, thus to suppress the broadening of the seal
pattern. The broad-gap region is created by forming a dent on the
surface of the CF substrate or the TFT substrate facing the liquid
crystal layer. When a transfer material or sealant is applied to
such a dent, spreading of the sealant over the display area is
suppressed since the dent constitutes a broad-gap region.
[0157] There is a variety of methods for forming a dent on the
surface of the substrate. For example, in the case where a resin
film is to be formed on the TFT substrate, a dent or a throughhole
may be formed at a predetermined position in the resin film. Such a
resin film may be utilized for forming an interlayer insulating
film which is to be provided between the TFTs or signal lines
formed on the TFT substrate and the pixel electrodes, for example.
Alternatively, various resin layers (e.g., colored resin layers) to
be formed on the color filter substrate may also be utilized.
[0158] Hereinafter, an example will be described where a broad-gap
region is created by utilizing a resin layer which is formed as an
interlayer insulating film on the TFT substrate. While the
aforementioned common transfer sealing portion 32c will be
illustrated as a possible site of broadening of the sealing
portion, it will be appreciated that the same principle is broadly
applicable to any part of the sealing portion at which an increase
in the width of the seal pattern is expected, e.g., junctions or
corner portions. Furthermore, a broad-gap region may be used in
combination of any structure in which a light shielding layer
includes a light-transmitting portion(s) as described in the
embodiments above.
[0159] FIGS. 18A, 18B, 18C, and 18D are schematic illustrations
each showing the structure of a common transfer sealing portion in
a liquid crystal display panel according to an embodiment of the
present invention. FIGS. 18A, 18C, and 18D are plan views; and FIG.
18B is a cross-sectional view taken along line 18B-18B' in FIG.
18A.
[0160] As shown in FIG. 18A, a resin layer 61 is provided on the
sealing portion 32, with a throughhole 61a being formed at the
portion of the resin layer 61 corresponding to the common transfer
section 60. The throughhole 61a defines a broad-gap region.
Although an example is described where the throughhole 61a is sized
similarly to the common pad 60a, the present embodiment is not
limited thereto.
[0161] The sealing portion 32 is formed by applying a sealant in
such a manner that the sealing portion 32 takes a predetermined
line width in any portion where the gap is equal to a gap value
which is determined by the design of the liquid crystal display
panel (i.e., the thickness of the liquid crystal layer). Because of
the throughhole 61a, the gap in the region where the common
transfer sealing portion 32c is formed is increased by a distance
equal to the film thickness of the resin layer 61. Since the
sealant which being applied in a linear shape has a constant
cross-sectional area, the seal width will become comparatively
smaller at the throughhole 61a in the resin layer 61; for example,
if it were not for the common transfer section 60, the line width
of the seal will be reduced at the dent (throughhole 61a) as shown
in FIG. 18C. When a common transfer substance is applied, the
sealant will spread out as dictated by the volume of the common
transfer substance, thus resulting in a structure as shown in FIG.
18A.
[0162] For example, the common transfer sealing portion 32c had a
maximum width of 1100 .mu.m in an experimentation example performed
under the following conditions: the resin layer had a film
thickness of 2.5 .mu.m; the sealing portion 32 had a width of about
1000 .mu.m; the sealing portion had a gap of 5.5 .mu.m where the
resin layer existed; the throughhole 61a in the resin layer had a
width of 1200 .mu.m; and the target diameter the common transfer
section 60 (in the theoretical case where no seal existed) was 500
.mu.m.
[0163] Preferably, the throughhole 61a in the resin layer 61 of the
present embodiment has a width which is greater than the diameter
of the common transfer section 60 or the maximum value of the width
of the main sealing portion (main stretch). In a similar
experimentation where no throughhole was made in the resin layer,
the common transfer sealing portion showed a maximum width of about
1400 .mu.m. Therefore, according to the present embodiment of the
invention, the width of the common transfer sealing portion 32c
including the common transfer section 60 was reduced by 300 .mu.m
as compared to the conventional case. The 300 .mu.m reduction in
the width of the recess 22a of the light shielding layer indicates
that a further narrowed frame region is made possible than in the
embodiments above.
[0164] Furthermore, in another case where the target diameter of
the common transfer section 60 (in the theoretical case where no
seal existed) was set at 400 .mu.m, the common transfer sealing
portion 32c had a maximum line width of about 1000 m. In this case,
since the maximum line width is equal to the width (1000 .mu.m) of
the main sealing portion 32, it is possible to omit the recess 22a
in the light shielding layer 22A, as exemplified in FIG. 18D.
[0165] It is not necessary that the throughhole 61a in the resin
layer 61 be so wide as to encompass the entire width of the sealing
portion. This point will be described with reference to FIGS. 19A,
19B, 19C, and 19D.
[0166] FIGS. 19A, 19B, 19C, and 19D are schematic illustrations
each showing the structure of a common transfer sealing portion in
a liquid crystal display panel according to another embodiment of
the present invention. FIGS. 19A, 19B, and 19C are plan views; and
FIG. 19B is a cross-sectional view taken along line 19B-19B' in
FIG. 19A.
[0167] For example, a sufficient effect can be obtained even if the
throughhole 61a in the resin layer 61 extends only part of the
width of the sealing portion as shown in FIG. 19A. Such a structure
will be particularly effective in the case where the final diameter
of the common transfer section is smaller than the width of the
sealing portion. The reason is that, in such a case, it is possible
to ignore any width increment due to the sealant being pushed out
by the common transfer section 60 toward the side where the resin
layer 61 lacks the throughhole (or dent) 61a (i.e., toward the
opposite side from the display region in FIG. 19A).
[0168] In the case where a resin layer that is formed for another
purpose is conveniently utilized es the aforementioned resin layer,
and must have a large film thickness, the addition of the
throughhole 61a may result in the width of the sealing portion
being too thin. However, the structure as shown in FIG. 19A can
counteract this problem and secure a sufficient seal width. Note
that an excessively thin seal width may result in problems
associated with insufficient strength of the sealing portion.
[0169] FIG. 20 is a graph showing a relationship between the
thickness of the resin layer 61 (depth of the throughhole 61a) and
the effect of reducing the width of the sealing portion 32.
[0170] From FIG. 20, it can be seen that better effects are
obtained as the resin film thickness is greater (i.e., the gap of
the broad-gap region is wider) and the main seal width is greater.
In a simple simulation, the line width reduction effect can be
expressed by the following equation:
((main seal width.times.gap of main sealing portion)/(gap of main
sealing portion+depth of dent in resin)}+common transfer
diameter-(common transfer diameter+main seal line width).
[0171] The "common transfer diameter" as used in the above equation
is the final diameter of the common transfer substance in the case
where the common transfer substance has no contact with the seal.
Although the above simulation equation does not take into account
the shape of the common transfer substance and therefore would not
accurately match the actual result, substantially similar effects
will nonetheless be obtained.
[0172] In order to actually obtain the aforementioned effects, it
is preferable that the gap in the broad-gap region be at least
about 10% greater than the gap of the sealing portion (i.e., the
gap of any region of the sealing portion other than the broad-gap
region) because the variations in line width occurring during
production must be absorbed to a certain extent. Although the above
example illustrates an example where a throughhole 61a is provided
in the resin layer 61, a dent (hole) may be provided instead of a
throughhole. A dent may be formed by a half exposure technique
using a photosensitive resin (photoresist), for example. When a
dent is to be formed by a half exposure technique using a positive
type photosensitive resin, an exposure and development is performed
before reaching an irradiation time which would effect complete
photolysis, so as to form a dent (hole). In the case of using a
negative type, on the other hand, an exposure and development is
performed before reaching an irradiation time which would effect
complete photocuring, so as to form a dent (hole). Forming a dent
by a half exposure technique provides an advantage in that the dent
depth is controllable. Note that a throughhole must not be formed
in the photosensitive resin layer in the case where leakage between
conductive layers which are provided above and below the
photosensitive resin layer cannot be tolerated; in such a case, it
is suitable to form a hole (dent), as opposed to a complete
throughhole.
[0173] The layer in which to form a throughhole or a dent (hole) is
not limited to an interlayer insulating film, but may also be a
resin layer for forming a black matrix or an overcoating resin
layer. If a photosensitive resin layer is used, the throughhole or
dent can be formed by a simple process. Alternatively an inorganic
material layer may be used, although this would make it difficult
to form a deep throughhole or dent. It is usually preferable that
the depth of any dent to be formed in the surface is in the range
of about 1 .mu.m to about 3 .mu.m, when taking into account
disadvantages such as the seal width becoming too thin.
[0174] It is preferable that the size of the throughhole or dent in
the resin layer (i.e., the size of the broad-gap region) be
prescribed so as to be smaller than the maximum value of the final
width of the common transfer section. In the embodiment shown in
FIGS. 19A to 19D, thinning of the width of the sealing portion can
be controlled based also on the pattern and arrangement of the
throughholes 61a, so that an optimum structure can be selected from
a broader range. For example, similar effects were confirmed in the
case where the edge of the throughhole 61a was at a position which
was 300 .mu.m outside of the center of the sealing portion 32 along
the width direction, under the same conditions as those described
above. It would be preferable that the edge of the throughhole 61a
be located at a position such that the outer edge of the sealing
portion would not fall into the throughhole 61a even in the case
where the sealing portion has a minimum line width given the
process variations.
[0175] According to the present invention, there is provided a
method which can efficiently produce a liquid crystal display panel
having an undecreased reliability even if a portion is formed
within the liquid crystal display panel which, under the
conventional production method, would result in a thick seal
pattern width (e.g., a sealing junction or a transfer section). In
particular, the present invention makes it possible to efficiently
produce a large-sized liquid crystal display panel by using a one
drop filling technique.
[0176] While the present invention has been described with respect
to preferred embodiments thereof, it will be apparent to those
skilled in the art that the disclosed invention may be modified in
numerous ways and may assume many embodiments other than those
specifically described above. Accordingly, it is intended by the
appended claims to cover all modifications of the invention that
fall within the true spirit and scope of the invention.
[0177] This non-provisional application claims priority under 35
USC .sctn.119(a) on Patent Applications No. 2004-208170 filed in
Japan on Jul. 15, 2004 and No. 2004-346915 filed in Japan on Nov.
30, 2004, the entire contents of which are hereby incorporated by
reference.
* * * * *