U.S. patent application number 10/394545 was filed with the patent office on 2003-10-02 for organic electro-luminescent display panel and method for manufacturing same.
Invention is credited to Ishii, Ikuko, Ooishi, Mitsuma, Sakaguchi, Yoshikazu, Suzuki, Joji.
Application Number | 20030186018 10/394545 |
Document ID | / |
Family ID | 18504512 |
Filed Date | 2003-10-02 |
United States Patent
Application |
20030186018 |
Kind Code |
A1 |
Ishii, Ikuko ; et
al. |
October 2, 2003 |
Organic electro-luminescent display panel and method for
manufacturing same
Abstract
An organic electro-luminescent display panel and a method of
manufacturing same are provided which are capable of reliably
holding a hygroscopic agent in its sealing cap in a uniform and
thin state and of being easily manufactured and of being configured
to be of a thin-profile type, without sacrificing light-emitting
characteristics and display contrast. The organic
electro-luminescent display panel is constructed of a transparent
insulating substrate, an organic electro-luminescent device formed
on the transparent insulating substrate and a sealing cap to make
up sealed space hermetically containing the organic
electro-luminescent device in cooperation with the insulating
substrate. The hygroscopic agent is enclosed hermetically in the
sealed space and is of a powder or grain type, which is sandwiched
between the sealing cap and an air-permeable sheet.
Inventors: |
Ishii, Ikuko; (Tokyo,
JP) ; Sakaguchi, Yoshikazu; (Tokyo, JP) ;
Ooishi, Mitsuma; (Tokyo, JP) ; Suzuki, Joji;
(Tokyo, JP) |
Correspondence
Address: |
KATTEN MUCHIN ZAVIS ROSENMAN
575 MADISON AVENUE
NEW YORK
NY
10022-2585
US
|
Family ID: |
18504512 |
Appl. No.: |
10/394545 |
Filed: |
March 21, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10394545 |
Mar 21, 2003 |
|
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09750805 |
Dec 28, 2000 |
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6551724 |
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Current U.S.
Class: |
428/68 ; 156/230;
156/235; 156/275.5; 156/291; 156/67; 257/100; 257/98; 313/504;
313/512; 428/192; 428/690; 428/76; 428/917 |
Current CPC
Class: |
Y10T 428/23 20150115;
H01L 51/5259 20130101; H05B 33/04 20130101; H05B 33/10 20130101;
H01L 27/32 20130101; Y10T 428/24777 20150115; Y10S 428/917
20130101; Y10T 428/239 20150115 |
Class at
Publication: |
428/68 ; 428/76;
428/192; 428/690; 428/917; 313/504; 313/512; 257/98; 257/100;
156/67; 156/230; 156/235; 156/275.5; 156/291 |
International
Class: |
H05B 033/02; H05B
033/10; B32B 003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 28, 1999 |
JP |
374834/1999 |
Claims
What is claimed is:
1. An organic electro-luminescent display panel comprising: a
transparent insulating substrate; an organic electro-luminescent
device formed on said transparent insulating substrate; a sealing
cap to make up sealed space hermetically containing said organic
electro-luminescent device in cooperation with said transparent
insulating substrate; and wherein hygroscopic agent is enclosed
hermetically in said sealed space and disposed in a manner to be
sandwiched between said sealing cap and an air-permeable sheet.
2. The organic electro-luminescent display panel according to claim
1, wherein a gluing agent layer to which said hygroscopic agent is
stuck is mounted on an inside surface of, at least, either of said
sealing cap or said air-permeable sheet.
3. The organic electro-luminescent display panel according to claim
1, wherein said hygroscopic agent is of a powder or grain type.
4. The organic electro-luminescent display panel according to claim
1, wherein said air-permeable sheet is a dark color sheet.
5. The organic electro-luminescent display panel according to claim
4, wherein said air-permeable sheet is an ultraviolet-ray blocking
sheet.
6. The organic electro-luminescent display panel according to claim
1, wherein said hygroscopic agent is stuck to said air-permeable
sheet with an adhesive sandwiched between said hygroscopic agent
and said air-permeable sheet.
7. The organic electro-luminescent display panel according to claim
6, wherein said gluing agent layer is mounted on a main surface of
said air-permeable sheet being opposite to said sealing cap and
wherein said hygroscopic agent in powder or grain form is stuck to
said air-permeable sheet with a region of said gluing agent layer
other than its edge region sandwiched between said hygroscopic
agent and said air-permeable sheet while said air-permeable sheet
is bonded to said sealing cap with said edge region of said gluing
agent layer sandwiched between said air-permeable sheet and said
sealing cap.
8. A method for manufacturing an organic electro-luminescent
display panel to produce said organic electro-luminescent display
panel provided with a transparent insulating substrate, an organic
electro-luminescent device formed on said transparent insulating
substrate and a sealing cap hermetically containing said organic
electro-luminescent device to form sealed space enclosing
hygroscopic agent in cooperation with said transparent insulating
substrate, said method comprising: a process of preparing an
air-permeable sheet provided with a gluing agent layer covered with
released paper on its surface; a process of partitioning a region
of said gluing agent layer into a first gluing agent region for
sticking said hygroscopic agent in powder or grain form and second
gluing agent region for bonding said air-permeable sheet to said
sealing cap; a process of peeling off a portion of said released
paper covering said first gluing agent region to expose said first
gluing agent region and sticking said hygroscopic agent in powder
or grain form to exposed said first gluing agent region; and a
process of peeling off a remaining portion of said released paper
to expose said second gluing agent region and bonding said
air-permeable sheet with said hygroscopic agent being stuck to said
sealing cap with exposed said second gluing agent region sandwiched
between said air-permeable sheet and said sealing cap.
9. A method for manufacturing an organic electro-luminescent
display panel to produce said organic electro-luminescent display
panel provided with a transparent insulating substrate, an organic
electro-luminescent device formed on said transparent insulating
substrate and a sealing cap hermetically containing said organic
electro-luminescent device to form sealed space enclosing
hygroscopic agent in cooperation with said transparent insulating
substrate, said method comprising: a process of preparing an
air-permeable sheet with a gluing agent layer mounted on a surface
of said air-permeable sheet; a process of partitioning a region of
said gluing agent layer into a first gluing agent region for
sticking said hygroscopic agent in powder or grain form and second
gluing agent region for bonding said air-permeable sheet to said
sealing cap; a process of holding a mold member to said second
gluing agent region with said first gluing agent region being left
exposed and sticking said hygroscopic agent on exposed said first
gluing agent region to said first gluing agent region; and a
process of making said second gluing agent region exposed by
removing said mold member and bonding said air-permeable sheet with
said hygroscopic agent stuck to said sealing cap with exposed said
second gluing agent region sandwiched between said air-permeable
sheet and said sealing cap.
10. The method for manufacturing the organic electro-luminescent
display panel according to claim 8, wherein edge region of said
gluing agent layer is used as said second gluing agent region and
remaining region of said gluing agent layer other than said edge
region is used as said first gluing agent region.
11. The method for manufacturing the organic electro-luminescent
display panel according to claim 9, wherein edge region of said
gluing agent layer is used as said second gluing agent region and
remaining region of said gluing agent layer other than said edge
region is used as said first gluing agent region.
12. The method for manufacturing the organic electro-luminescent
display panel according to claim 8, wherein a demarcation line is
provided by giving a break to said released paper covering said
gluing agent layer to partition said region of said gluing agent
layer into said first gluing agent region and said second gluing
agent region.
13. The method for manufacturing the organic electro-luminescent
display panel according to claim 8, wherein, after said
air-permeable sheet to which said hygroscopic agent in powder or
grain form is stuck has been bonded to said sealing cap, said
sealing cap is junctioned, in an atmosphere of inert gas, to said
transparent insulating substrate by using an ultraviolet setting
adhesive sandwiched between said sealing cap and said transparent
insulating substrate.
14. The method for manufacturing the organic electro-luminescent
display panel according to claim 9, wherein, after said
air-permeable sheet to which said hygroscopic agent in powder or
grain form is stuck has been bonded to said sealing cap, said
sealing cap is junctioned, in an atmosphere of inert gas, to said
transparent insulating substrate by using an ultraviolet setting
adhesive sandwiched between said sealing cap and said transparent
insulating substrate.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an organic EL
(Electro-Luminescent) display device operating based on an
electro-luminescent phenomenon and a method for manufacturing a
same and more particularly to the organic EL display device in
which a hygroscopic agent is enclosed hermetically and a method for
manufacturing a same.
[0003] The present application claims priority of Japanese Patent
Application No. Hei 11-374834 filed on Dec. 28, 1999, which is
hereby incorporated by reference.
[0004] 2. Description of the Related Art
[0005] An EL display device using an electroluminescent phenomenon,
since it has various advantages in that it can be configured so as
to be of a spontaneous light-emitting type and of a thin flat-panel
type, that it draws less power, that it can provide better
viewability and fast responsivity and that it can display moving
images, is considered to be promising for wider applications. Two
types of EL display devices are known, one being an inorganic EL
display device employing inorganic materials and another being an
organic EL display device employing organic thin films. In recent
years, since various organic luminescent compounds have been
developed which enable light-emitting in multiple colors and allow
a full color EL display device to be implemented, development of
the organic EL display device is being promptly pursued. Such the
organic EL display device is fabricated based on a phenomenon in
which light is emitted when a hole injected from an anode and an
electron injected from a cathode are recombined in a light-emitting
layer composed of an organic luminescent substance having a
fluorescent capability contained in an organic thin-film sandwiched
between the anode and the cathode, that is, when they are changed
from an excited state to a deactivated state. Moreover, recent
prompt advancement of the EL display device is also attributable to
greatly improved light-emitting efficiency and luminance achieved
by employing a structure in which hole transporting layers and/or
electron transporting layers are stacked as the light-emitting
layer.
[0006] Though improvements have been made to increase its display
life to a considerable extent, there are still left many factors of
deterioration including occurrence of a dark spot being a region
where no light is emitted, and sufficiently satisfactory display
life has not yet been implemented. One of the factors of
deterioration is an influence of moisture which is a problem
specific to organic thin-film materials. That is, the organic EL
device using such organic thin-film materials is easily affected by
moisture existing in an area surrounding the organic EL display
device; for example, there is a case where moisture permeating
through an interface between a light-emitting layer and an
electrode interferes with injection of an electron, causing
occurrence of dark spots and corrosion of the electrode. To solve
this problem, methods for preventing or removing the influence of
moisture or a like by sealing the organic EL device hermetically
are proposed. To prevent the influence of moisture, the organic EL
device is put into a container being impermeable to moisture and is
then enclosed together with nitrogen gas hermetically. Moreover, to
remove the influence of moisture, a hygroscopic agent is enclosed
into the moisture-impermeable container in which the organic EL
device and the nitrogen gas are enclosed together.
[0007] FIG. 8 is a cross-sectional view of a conventional organic
EL display panel in a sealing cap of which a hygroscopic agent is
enclosed hermetically in order to remove an influence of moisture,
which is disclosed in Japanese Patent Application Laid-open No. Hei
9-148066 (hereinafter referred to as a "first conventional
example"). As shown in FIG. 8, the organic EL display device of the
first conventional example is mainly constructed of a transparent
glass substrate 51, an organic EL layer-stacked body 55 composed of
a transparent electrode 52 (as an anode) made from ITO (Indium Tin
Oxide) or a like, an EL light-emitting layer 53 made from an
organic EL material or a like and a counter electrode (as a
cathode) 54, each being stacked in this order, a glass sealing can
56 to seal the organic EL layer-stacked body 55 and a drying body
57 composed of a hygroscopic agent adhering to an inside surface of
the glass sealing can 56. To enclose the above drying body 57 in
the glass sealing can 56, two methods are available; one in which a
hygroscopic compound is solidified to produce a formed body which
is then fixed in the glass sealing can 56 and another in which the
hygroscopic compound is put into an air-permeable bag which is then
fixed in the glass sealing can 56.
[0008] FIG. 9 is a cross-sectional view of another conventional
organic EL display panel in a sealing cap of which a hygroscopic
agent is enclosed hermetically, which is disclosed in Japanese
Patent Application Laid-open No. Sho 61-96695 (hereinafter referred
to as a "second conventional example"). As shown in FIG. 9, the
organic EL display panel in the second conventional example is same
as that in the first conventional example in that an organic EL
device 62 formed on a glass substrate 61 is sealed hermetically by
a sealing cap 63. However, the organic EL display panel in the
second conventional example differs from that in the first
conventional example in that, instead of the drying body 57
employed in the first conventional example, a composite film 64
formed by making a composite substance composed of zeolite serving
as the hygroscopitc agent, a carbon powder serving as a
light-shielding substance, a light-absorbing substance and an
organic resin serving as a binder, into a film-like material, is
stuck to an inside surface of the sealing cap 63. By configuring as
above, an attempt has been made to implement the organic EL display
panel having a tolerable life characteristic and contrast and being
readily manufactured.
[0009] However, in the first conventional example, if the method in
which the hygroscopic compound is solidified by using a binder to
produce the formed body is employed when the drying body 57 is
enclosed in the glass sealing can 56, since an exposed surface area
of the hygroscopic agent is made small, it causes a decrease in
hygroscopic capability and, since mechanical strength of the formed
body is required to some extent, the drying body 57 is not allowed
to be thinner. Therefore, the organic EL display device of the
first conventional example is not suitable for application for a
thin-type organic EL display. Moreover, in the organic EL display
device of the first conventional example, if the method in which
the hygroscopic compound is put into the air-permeable bag which is
then fixed in the glass sealing can 56 is employed, it is difficult
to give a fixed shape to the drying body 57 because it is contained
in a bag having no definite shape and, when the organic EL display
panel is put in an inclined state, the drying body 57 containing
the hygroscopic agent easily moves and leans, causing a touch with
the organic EL layer-stacked body 55 which leads to deterioration
of the organic EL layer-stacked body 55 by an external force.
[0010] Moreover, in the second conventional example, if the
composite film 64 is peeled off from the sealing cap 63, it comes
in touch with the organic EL device 62, causing damage to the EL
device 62. Since hygroscopic agent, carbon powder and binder are
mixed to produce the composite film 64, there is a risk that a
function of the hygroscopic agent itself and/or a function of the
light-shielding substance itself cannot be sufficiently
implemented. Additionally, when components contained in the binder
being an organic resin are partially left unreacted, the organic EL
device is adversely affected by them.
SUMMARY OF THE INVENTION
[0011] In view of the above, it is an object of the present
invention to provide an organic EL display panel which is capable
of reliably holding a hygroscopic agent in its sealing cap in a
manner so as to be stuck in a uniform and thin state and of being
easily manufactured and of being configured to be of a thin-profile
type, without sacrificing light-emitting characteristics and
display contrast, and a method of manufacturing a same.
[0012] According to a first aspect of the present invention, there
is provided an organic EL display panel including:
[0013] a transparent insulating substrate;
[0014] an organic EL device formed on the transparent insulating
substrate;
[0015] a sealing cap to make up sealed space hermetically
containing the organic EL device in cooperation with the
transparent insulating substrate; and
[0016] wherein a hygroscopic agent is enclosed hermetically in the
sealed space and disposed in a manner to be sandwiched between the
sealing cap and an air-permeable sheet.
[0017] In the foregoing, a preferable mode is one wherein a gluing
agent layer to which the hygroscopic agent is stuck is mounted on
an inside surface of, at least, either of the sealing cap or the
air-permeable sheet.
[0018] Also, a preferable mode is one wherein the hygroscopic agent
is of a powder or grain type.
[0019] Also, a preferable mode is one wherein the air-permeable
sheet is a dark color sheet.
[0020] Also, a preferable mode is one wherein the air-permeable
sheet is an ultraviolet-ray blocking sheet.
[0021] Also, a preferable mode is one wherein the hygroscopic agent
is stuck to the air-permeable sheet with an adhesive sandwiched
between the hygroscopic agent and said air-permeable sheet.
[0022] Also, a preferable mode is one wherein the gluing agent
layer is mounted on a main surface of the air-permeable sheet being
opposite to the sealing cap and wherein the hygroscopic agent in
powder or grain form is stuck to the air-permeable sheet with a
region of the gluing agent layer other than its edge region
sandwiched between the hygroscopic agent and the air-permeable
sheet while the air-permeable sheet is bonded to the sealing cap
with the edge region of the gluing agent layer sandwiched between
the air-permeable sheet and the sealing cap.
[0023] According to a second aspect of the present invention, there
is provided a method for manufacturing an organic EL display panel
to produce the organic EL display panel provided with a transparent
insulating substrate, an organic EL device formed on the tansparent
insulating substrate and a sealing cap hermetically containing the
organic EL device to form sealed space enclosing hygroscopic agent
in cooperation with the transparent insulating substrate, the
method including:
[0024] a process of preparing an air-permeable sheet provided with
a gluing agent layer covered with released paper on its
surface;
[0025] a process of partitioning a region of the gluing agent layer
into a first gluing agent region for sticking the hygroscopic agent
in powder or grain form and second gluing agent region for bonding
the air-permeable sheet to the sealing cap;
[0026] a process of peeling off a portion of the released paper
covering the first gluing agent region to expose the first gluing
agent region and sticking the hygroscopic agent in powder or grain
form to the exposed first gluing agent region; and
[0027] a process of peeling off a remaining portion of the released
paper to expose the second gluing agent region and bonding the
air-permeable sheet with the hygroscopic agent being stuck to the
sealing cap with the exposed second gluing agent region sandwiched
between the air-permeable sheet and the sealing cap.
[0028] According to a third aspect of the present invention, there
is provided a method for manufacturing an organic EL display panel
to produce said organic EL display panel provided with a
transparent insulating substrate, an organic EL device formed on
said transparent insulating substrate and a sealing cap
hermetically containing said organic EL device to form sealed space
enclosing a hygroscopic agent in cooperation with the transparent
insulating substrate, the method including:
[0029] a process of preparing an air-permeable sheet with a gluing
agent layer mounted on a surface of the air-permeable sheet;
[0030] a process of partitioning a region of the gluing agent layer
into a first gluing agent region for sticking the hygroscopic agent
in powder or grain form and second gluing agent region for bonding
the air-permeable sheet to the sealing cap;
[0031] a process of holding mold members to the second gluing agent
region with the first gluing agent region being left exposed and
sticking the hygroscopic agent on the exposed first gluing agent
region to the first gluing agent region; and
[0032] a process of making the second gluing agent region exposed
by removing the mold members and bonding the air-permeable sheet
with the hygroscopic agent stuck to the sealing cap with the
exposed second gluing agent region sandwiched between the
air-permeable sheet and the sealing cap.
[0033] In the foregoing, it is preferable that edge portion of the
gluing agent layer is used as the second gluing agent region and
remaining portion of the gluing agent layer other than the edge
portion is used as the first gluing agent region.
[0034] Also, it is preferable that a demarcation line is provided
by giving a break to the released paper covering the gluing agent
layer to partition the gluing agent region into the first gluing
agent region and the second gluing agent region.
[0035] Furthermore, it is preferable that, after the air-permeable
sheet to which the hygroscopic agent in powder or grain form is
stuck has been bonded to the sealing cap, the sealing cap is
junctioned, in an atmosphere of inert gas, to the transparent
insulating substrate by using an ultraviolet setting adhesive
sandwiched between the sealing cap and the transparent insulating
substrate.
[0036] With the above configurations, since the organic EL display
device is so constructed that the hygroscopic agent in powder or
grain form is uniformly held on the air-permeable sheet using the
gluing agent layer mounted to the back of the air-permeable sheet,
it is possible to fabricate the organic EL display device of a
thinner type and to prevent the hygroscopic agent from being moved
and leaning within the sealing cap. Moreover, even when the
hygroscopic agent happens to be peeled, since it is held by the
air-permeable sheet, deterioration of the organic EL device can be
prevented. Furthermore, since the hygroscopic agent is of the
powder or grain type, a wide surface area of the hygroscopic agent
is secured, thus providing a high hygroscopic efficiency and a
stable light-emitting characteristic. Also, by using the dark color
sheet, visible light can be absorbed, thus preventing reflection of
light from the back when the organic EL display panel is ON and
providing excellent display contrast.
[0037] With another configuration as above, since the air-permeable
sheet with the gluing agent layer covered with the released paper
is used and the region of the gluing agent layer is partitioned
into two regions, one being the first gluing agent region (the
region other than its edge region) used for sticking the
hygroscopic agent in powder or grain form to the air-permeable
sheet and the other being the second gluing agent region (edge
region) used for bonding the air-permeable sheet to the sealing cap
and the released paper existing inside the demarcation line is
peeled off to stick the hygroscopic agent to the first gluing agent
region while the released paper existing outside the demarcation
line is peeled off to bond the sealing cap to a glass substrate
with the second gluing agent region sandwiched between them, when
the hygroscopic agent is stuck to the first gluing agent region, a
trouble of adhesion of the hygroscopic agent to the second gluing
region can be prevented and therefore weakening of the adhesive
strength of the second gluing region to bond the sealing cap to the
glass substrate can be avoided, thus enabling prompt, easy and
reliable mounting of the hygroscopic agent. Moreover, by using the
ultraviolet-ray blocking type air-permeable sheet, when
ultraviolet-ray setting adhesive is irradiated with ultraviolet
rays from the sealing cap side, the organic EL light-emitting layer
being susceptible to ultraviolet rays can be protected efficiently
against ultraviolet rays.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] The above and other objects, advantages and features of the
present invention will be more apparent from the following
description taken in conjunction with the accompanying drawings in
which:
[0039] FIG. 1 is a cross-sectional view showing configurations of
an organic EL display panel according to a first embodiment of the
present invention;
[0040] FIGS. 2A to 2C are process diagrams showing a process, that
is, a process of forming the organic EL layer-stacked body, in a
method of manufacturing the organic EL display panel according to
the first embodiment;
[0041] FIGS. 3A to 3D are process diagrams showing another process,
that is a process of fabricating the sealing cap, in the method of
manufacturing the organic EL display panel according to the first
embodiment;
[0042] FIGS. 4A and 4B are process diagrams showing still another
process, that is a process of sealing the organic EL layer-stacked
body, in the method of manufacturing the organic EL display panel
according to the first embodiment;
[0043] FIG. 5 is a transverse cross-sectional view of the organic
EL display panel of FIG. 4B taken along a line X-X in a direction
of arrows;
[0044] FIGS. 6A to 6E are process diagrams showing, in order of
processes, a method of manufacturing an organic EL display panel
according to a second embodiment of the present invention;
[0045] FIG. 7 is a cross-sectional view of a modified organic EL
display panel according to the first or second embodiment of the
present invention;
[0046] FIG. 8 is a cross-sectional view of a first conventional
organic EL display panel in a sealing cap of which a hygroscopic
agent is enclosed hermetically; and
[0047] FIG. 9 is a cross-sectional view of a second conventional
organic EL display panel in a sealing cap of which a hygroscopic
agent is enclosed hermetically.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0048] Best modes of carrying out the present invention will be
described in further detail using various embodiments with
reference to the accompanying drawings.
First Embodiment
[0049] FIG. 1 is a cross-sectional view showing configurations of
an organic EL display panel according to a first embodiment of the
present invention. FIGS. 2A to 2C are process diagrams
illustrating, in order of processes, one method for manufacturing
the organic EL display panel according to the first embodiment.
FIGS. 3A to 3D are process diagrams illustrating, in order of
processes, another method for manufacturing the organic EL display
panel according to the first embodiment. FIGS. 4A and 4B are also
process diagrams illustrating, in order of processes, still another
method for manufacturing the organic EL display panel according to
the first embodiment of the present invention. FIG. 5 is a
transverse cross-sectional view of the organic EL display panel of
FIG. 4B taken along a line X-X in a direction of arrows.
[0050] The organic EL display panel of the first embodiment is a
direct-current-drive type organic EL display panel in upper and
lower portions of an organic EL layer-stacked body of which
electrode layers are formed where its anode is formed on a glass
substrate side. As shown in FIG. 1, the organic EL display device
of the first embodiment is mainly composed of a transparent and
flat glass substrate 1, an organic EL layer-stacked body 30
disposed on the transparent and flat glass substrate 1 in which a
transparent electrode (anode) 2, an organic EL light-emitting layer
3 made from an organic electroluminescent material and a counter
electrode (cathode) 4 are stacked in this order, a sealing cap 5 to
seal the organic EL layer-stacked body 30, a hygroscopic agent 6 in
powder or grain form adhering to an inside surface of the sealing
cap 5 placed opposite to the organic EL layer-stacked body 30 and
an air-permeable sheet 7 adapted to cover the hygroscopic agent 6
and hold it.
[0051] The organic EL light-emitting layer 3 is composed of a hole
transporting layer 3a made from a triphenylamine derivative or a
like, a light-emitting layer 3b made from a stilbene derivative or
a like and an electron transporting layer 3c made from a perylene
derivative or a like, each being stacked in order. Moreover, the
transparent electrode 2 composed of ITO or a like and the counter
electrode 4 are formed in a manner that they intersect at right
angles with the organic EL light-emitting layer 3 sandwiched
between the transparent electrode 2 and the counter electrode 4.
Two or more transparent electrodes 2 are arranged in parallel, in a
specific pattern and in a stripe-like form and organic EL picture
elements serving as light-emitting display units are formed at
points of intersection of the transparent electrodes 2 and the
counter electrodes 4, which make up a dot-matrix type display
device.
[0052] The sealing cap 5 is formed as a capping body constructed of
a bottom plate portion (with a thickness of about 0.2 mm) placed
opposite to the organic EL layer-stacked body 30 formed on the
transparent and flat glass substrate 1 and a side wall portion
(with a height of about 0.4 mm) formed in a manner that it erects
along an edge region of the bottom plate portion. The sealing cap 5
has a concave section with a depth of about 0.4 mm. An upper end of
the side wall portion is stuck to the transparent and flat glass
substrate 1 using an ultraviolet-ray setting type adhesive 8 (not
shown) which is sandwiched between the sealing cap 5 and the
transparent and flat glass substrate 1. In a cavity of the concave
section is hermetically enclosed inert gas 9 such as argon gas or a
like. Thus, the organic EL layer-stacked body 30 is sealed
hermetically by the sealing cap 5.
[0053] On a bottom face of the sealing cap 5 is mounted the
air-permeable sheet 7 with a thickness of 20 .mu.m to 20 .mu.m in a
manner that a clearance is left to an extent that the air-permeable
sheet 7 does not come in touch with the organic EL layer-stacked
body 30. The hygroscopic agent 6 in powder or grain form is
inserted between the air-permeable sheet 7 and the bottom face of
the concave section of the sealing cap 5 in a manner that the
hygroscopic agent 6 and the air-permeable sheet 7 are fitly housed
in the sealing cap 5. Moreover, an air-permeable gluing agent layer
10 is formed on a face, out of two faces including a surface and a
back face of the air-permeable sheet 7, being opposite to the
sealing cap 5. A region other than edge portion of the
air-permeable gluing agent layer 10 is used to uniformly hold the
hygroscopic agent 6 on the air-permeable sheet 7 and the edge
portion of the air-permeable gluing agent layer 10 is used to bond
the air-permeable sheet 7 to the sealing cap 5.
[0054] A material for the air-permeable sheet 7 must have
properties that it does not allow the hygroscopic agent 6 in powder
or grain form to be permeated and allows air to be permeated and
that it can absorb visible light and can block ultraviolent rays.
Therefore, in the first embodiment, woven or nonwoven fabric of a
black cloth, paper, synthetic resin such as a nylon, ethylene
tetrafluoride resin or a like may be used, if necessary, after
coloring them. As a gluing agent used for the air-permeable gluing
agent layer 10 in the first embodiment, preferably a rubber,
acrylic or silicone gluing agent may be used.
[0055] Though both a hygroscopic agent chemically absorbing
moisture and a hygroscopic agent physically absorbing moisture may
be used as the hygroscopic agent 6 in the first embodiment, the
hygroscopic agent that can be made powdered or granular should be
used. The hygroscopic agent 6 that may be preferably used in the
first embodiment includes diphosphorous pentaoxide, anhydrone,
dehydrite, anhydrous calcium sulfate, anhydrous calcium sulfide,
calcium hydroxide, anhydrous calcium chloride, alkaline earth metal
oxide such as calcium oxide, magnesium oxide, activated alumina,
silica gel, charcoal or a like. These are examples and the present
invention is not limited to these substances. Moreover, the powder
or the grain of the hygroscopic agent 6 is preferably 10 .mu.m to
200 .mu.m in diameter.
[0056] Next, a method for manufacturing the organic EL display
panel having configurations as explained above will be described
hereinafter by referring to FIG. 2A to FIG. 5. The organic EL
display panel of the first embodiment is fabricated with processes
including a process of forming the organic EL layer-stacked body 30
on the transparent and flat glass substrate 1, a process of
mounting the hygroscopic agent 6 in powder or grain form and the
air-permeable sheet 7 used to coat and hold the hygroscopic agent 6
in the concave regions of the sealing cap 5 in a manner that the
hygroscopic agent 6 and air-permeable sheet 7 are fitly housed
within the sealing cap 5 and a process of sealing the organic EL
layer-stacked body 30 formed on the transparent and flat glass
substrate 1. First, the process of forming the organic EL
layer-stacked body 30 on the transparent and flat glass substrate 1
will be described by referring to FIGS. 2A to 2C. The transparent
and flat glass substrate 1 is first prepared, on a back surface of
which ITO or a like is deposited and patterning is performed using
photolithography to form the transparent electrode 2 which is
stripe-like (see FIGS. 2A and 2C). Then, on the transparent and
flat glass substrate 1 where the transparent electrode 2 is formed,
a triphenylamine derivative, a stilbene derivative and a perylene
derivative are sequentially deposited and, using a shadow mask,
films having a desired pattern are formed to obtain the organic EL
light-emitting layer 13 composed of a stacked hole transporting
layer 3a, light-emitting layer 3b, electron transporting layer 3c
(see FIGS. 2B and 2C). Finally, an aluminum film is formed by using
a deposition method and patterning is performed using a mask to
form the counter electrode (cathode) 4 disposed to be orthogonal to
the transparent electrode 2 (see FIGS. 2B and 2C).
[0057] Next, a process of fabricating the sealing cap 5 in which
the hygroscopic agent 6 and the air-permeable sheet 7 are housed is
described by referring to FIGS. 3A to 3D. First, as shown in FIG.
3D, the sealing cap 5 having the concave region with a depth of
about 0.4 mm is assembled. The sealing cap 5 is obtained by
sticking a transparent glass plate for the bottom plate portion
with a thickness of about 0.2 mm to a glass piece for the side wall
portion with a height of about 0.4 mm. Moreover, such the sealing
cap 5 may be fabricated by forming the concave region by carrying
out a sandblast process on transparent glass plate or by thermally
forming a region surrounding transparent glass plate. The
air-permeable sheet 7 to a surface of which the air-permeable
gluing agent layer 10 covered with released paper 11 is attached
and which is composed of black cloth, paper or a synthetic resin is
prepared in a manner as shown in FIG. 3A. A demarcation line (not
shown) is then provided to partition an entire region of the
air-permeable gluing agent layer 10 attached to the air-permeable
sheet 7 into a first gluing agent region 10a to be used for
sticking the hygroscopic agent 6 in powder or grain form (the
region other than edge portion) to the air-permeable sheet 7 and a
second gluing agent region 10b (edge portion) to be used for
bonding the air-permeable sheet 7 to the sealing cap 5, in advance,
to the air-permeable gluing agent layer 10 as shown in FIG. 3B.
Then, a break 11a is given, with a cutter (not shown), along the
demarcation line (see FIG. 3B and FIG. 5), on the released paper 11
covering the air-permeable gluing agent layer 10.
[0058] Next, the released paper 11 existing inside the break 11a is
peeled off, as shown in FIG. 3B, to make the first gluing agent
region 10a exposed and then the hygroscopic agent 6 is provided in
a manner that it adheres uniformly to the entire first gluing agent
region 10a, as shown in FIG. 3C. At this point, uniform adhesion of
the hygroscopic agent 6 is achieved by shaking off excessive
hygroscopic agent 6 not adhering to the air-permeable gluing agent
layer 10. By shaking off excessive hygroscopic agent 6, a thin,
single and reproducible layer of the hygroscopic agent 6 is formed
on the air-permeable gluing agent layer 10.
[0059] Remaining portions (the edge portion) of the released paper
11 are peeled off to make the second gluing agent region 10b
exposed and the air-permeable sheet 7 to which the hygroscopic
agent 6 is stuck is bonded to the sealing cap 5, with the exposed
second gluing agent region 10b sandwiched between the air-permeable
sheet 7 and the sealing cap 5.
[0060] Next, a process of sealing the organic EL layer-stacked body
30 formed on the transparent and flat glass substrate 1 by using
the sealing cap 5 containing the hygroscopic agent 6 and
air-permeable sheet 7 will be described by referring to FIGS. 4A
and 4B. First, as shown in FIG. 4A, a coating of the
ultraviolet-ray setting adhesive 8 is applied to an upper end of
the side wall portion of the sealing cap 5. The sealing cap 5 is
put on the organic EL layer-stacked body 30 in an atmosphere of
inert gas 9 such as argon gas and an upper end of the sealing cap 5
is then bonded to the transparent and flat glass substrate 1 with
unhardened ultraviolet ray setting adhesive 8 sandwiched between
the upper end of the sealing cap 5 and the transparent and flat
glass substrate 1. Then, as shown in FIG. 4B, the hygroscopic agent
6 is irradiated with ultraviolet rays from the sealing cap side 5
to solidify the air-permeable gluing agent layer 10 for sticking
the hygroscopic agent 6. Solidification of the ultraviolet ray
setting adhesive 8 causes the sealing cap 5 to be bonded to the
transparent and flat glass substrate 1 and the organic EL
layer-stacked body 30 is enclosed hermetically with the inert gas 9
such as the argon gas enclosed hermetically in the cavity of the
concave section in the sealing cap 5. Thus, production of the
organic EL display panel of the first embodiment is completed.
[0061] As described above, according to the first embodiment, since
the hygroscopic agent 6 in powder or grain form is uniformly stuck
to the air-permeable sheet 7 by using the air-permeable gluing
agent layer 10 mounted to the back of the air-permeable sheet 7,
the organic EL display panel can be so configured to be of a
thin-profile type.
[0062] Also, according to the first embodiment, since the
hygroscopic agent 6 is of the powdered or the granular type,
allowing a wider surface area to be secured, it is made possible to
obtain a high hygroscopic efficiency and to maintain stable
light-emitting performance. Moreover, since the air-permeable sheet
7 can absorb visible light, reflection of light from a rear side
can be prevented when the organic EL display panel is ON, thus
providing excellent display contrast.
[0063] Also, according to the first embodiment, in the method for
manufacturing the organic EL display panel of the embodiment, by
using the air-permeable sheet 7 provided with the air-permeable
gluing agent layer 10 being covered with the released paper 11 and
by giving the break 11a, with the cutter (not shown), to the
released paper 11, the area of the air-permeable gluing agent layer
10 is partitioned into two regions, one being the first gluing
agent region 10a (the region other than edge region) to be used for
sticking the hygroscopic agent 6 in powder or grain form and the
other region being the second gluing agent region 10b to be used
for bonding the air-permeable sheet 7 to the sealing cap 5 (edge
region) and the released paper 11 existing inside the break 11a is
peeled off to stick the hygroscopic agent 6 to the first gluing
agent region 10a while the released paper 11 existing outside the
break 11a is peeled off to bond the sealing cap 5 to the
transparent and flat glass substrate 1 with the second gluing agent
region 10b sandwiched between the sealing cap 5 and the transparent
and flat glass substrate 1. Thus, this method makes it possible to
mount the hygroscopic agent 6 promptly, readily and reliably in a
manner that it can be mounted uniformly.
[0064] Furthermore, according to the first embodiment, since the
air-permeable sheet 7 can block ultraviolet rays, the organic EL
light-emitting layer 3 being susceptible to ultraviolet rays can be
protected efficiently when the hygroscopic agent 6 is irradiated
with the ultraviolet rays from the sealing cap 5 side.
Second Embodiment
[0065] FIGS. 6A to 6E are process diagrams showing, in order of
processes, a method of manufacturing an organic EL display panel
according to a second embodiment of the present invention. The
method of manufacturing the organic EL display panel of the second
embodiment differs greatly from that of the first embodiment in
that a released paper mold 12 is newly employed as shown in FIGS.
6A to 6D to fabricate the organic EL display panel, instead of a
released paper 11 (see FIG. 3A) adapted to protect an entire
surface of an air-permeable gluing agent layer 10 being stuck to an
air-permeable sheet 7 used in the first embodiment. That is, as
shown in FIGS. 6A to 6D, the released paper mold 12 has its opening
portion 12a to be used as a jig for sticking a hygroscopic agent 6
to the air-permeable gluing agent layer 10. The released paper mold
12 is so configured that a length of an opening portion 12a of the
released paper mold 12, that is, a diameter of a hole formed in the
released paper mold 12 as the opening portion is equal to a length
of a first gluing agent region 10a (a region other than edge
portion) of whole air-permeable gluing agent layer 10 and only the
first gluing agent region 10a is used for sticking the hygroscopic
agent 6.
[0066] A method for manufacturing the organic EL display panel of
the second embodiment will be explained below. In the second
embodiment, processes other than the process of sticking the
hygroscopic agent 6 in powder or grain format to an air-permeable
sheet 13 are same as those in the first embodiment and therefore,
in FIGS. 6A to 6E, same reference numbers are assigned to parts
having same functions as for the first embodiment and descriptions
of them are omitted accordingly.
[0067] In the method of the second embodiment, a coating of a
rubber, acrylic or silicone gluing agent (herein after called a
gluing agent) is applied to a back face of the air-permeable sheet
13 to form the air-permeable gluing agent layer 10 (see FIG. 6A).
Then, the released paper mold 12 which has been fabricated in
advance is held to the air-permeable gluing agent layer 10 composed
of the first gluing agent region 10a (the region other than its
edge region) to be used to stick the hygroscopic agent 6 and second
gluing agent region 10b (edge region) to be used for bonding the
air-permeable sheet 13 to a sealing cap 5 in a manner that the
second gluing agent region 10b and the end portion 12a of the
released paper mold 12 overlap each other (see FIG. 6B).
[0068] Then, the hygroscopic agent 6 is sprinkled on the
air-permeable gluing agent layer 10, to the second gluing agent
region 10b of which the end portion 12a of the released paper mold
12 is held. Due to a screen effect of the released paper mold 12,
however, the sprinkled hygroscopic agent 6 adheres only to a region
of the air-permeable gluing agent layer 10 within the opening
portion of the released paper mold 12, that is, only to the first
gluing agent region 10a (see FIG. 6C). Though the hygroscopic agent
6 has not yet adhered in a uniform and even state at this point, by
shaking off excessive hygroscopic agent 6 not adhering to the first
gluing agent region 10a, the uniform adhesion of the hygroscopic
agent 6 is implemented. That is, by shaking off excessive
hygroscopic agent 6, a thin, single and reproducible layer of the
hygroscopic agent 6 is formed on the first gluing agent region 10a.
After this process, the released paper mold 12 is removed from the
air-permeable gluing agent layer 10 (see FIG. 6D). The second
gluing agent region 10b are exposed when the released paper mold 12
has been taken off and exposed second gluing agent region 10b are
then used to bond the air-permeable sheet 13 to which the
hygroscopic agent 6 is stuck to the sealing cap 5.
[0069] Thus, according to the second embodiment, same effects
obtained by the first embodiment can be achieved. Additionally,
since the released paper mold 12 can be used any number of times,
it serves to reduce costs for fabrication.
[0070] It is apparent that the present invention is not limited to
the above embodiments but may be changed and modified without
departing from the scope and spirit of the invention. For example,
the sealing cap 5 composed of an opaque material may be used. The
organic EL display panel may be not only of a direct-current-drive
type but also of an alternating-current-drive type. The organic EL
layer-stacked body 30 may be not only of a three-layer structure
but also of two-layer or four-layer structure. Not only a
transparent and flat glass substrate 1 but also other substrate so
long as it is transparent may be employed. When the gluing agent
for sticking the hygroscopic agent 6 is solidified, it may be
irradiated with ultraviolet rays not only from the sealing cap 5
side but also from the transparent and flat glass substrate 1 side.
In the above embodiments, the hygroscopic agent 6 in powder or
grain form is stuck to the air-permeable sheet 13 by using the
gluing agent, however, instead of the gluing agent, an
air-permeable adhesive may be used. As the gluing agent layer 10, a
double-faced gluing tape or single-faced gluing tape may be used.
The sealing cap 5 does not necessarily require a concave portion
and also may be of a flat type if only a spacer to be used for a
side wall portion is used separately. In the above embodiments, the
edge region of the entire gluing agent region is used as the second
gluing agent region 10b to bond the air-permeable sheet 13 to the
sealing cap 5 and the region other than the edge region is used as
the first gluing agent region 10a to stick the hygroscopic agent 6
in powder or grain form, however, it is not necessarily required
that the edge region is set to the second gluing agent region 10b
and that the region other than the edge region is set to the first
gluing agent region 10a. In the above embodiments, apart of the
gluing agent region is used as the second gluing agent region 10b
to bond the air-permeable sheet 13 to the sealing cap 5, however,
by mounting an adhesive layer to both the sealing cap 5 and
air-permeable sheet 13, as shown in FIG. 7, the second gluing agent
region 10b may be removed, which allows more amounts of the
hygroscopic agent 6 to be mounted. It is also not necessarily
required that a color of the air-permeable sheet 13 is black so
long as it is of an ultraviolet-ray blocking type and that the
color of the air-permeable sheet 13 may be black so long as it is
of a visible-ray absorbing type or of an anti-reflective type.
Moreover, it is not necessarily required, depending applications or
methods of manufacturing, that the air-permeable sheet 13 is of a
visible-ray absorbing type, anti-reflective type or ultraviolet-ray
blocking type. In this case, the hygroscopic agent 6 in powder or
grain form in black color may be used. Depending on applications,
use of the air-permeable sheet 13 may be omitted and, if the
air-permeable sheet 13 is not used, the hygroscopic agent 6 in
powder or grain form may be stuck to an inner face of the sealing
cap 5 with the gluing agent or a gluing agent sheet sandwiched
between the hygroscopic agent 6 and the sealing cap 5. Furthermore,
it is not required that a material itself for the air-permeable
sheet 13 is of an air-permeable type, that is, any sheet may be
used as the air-permeable sheet 13 so long as it is provided with
permeability by, for example, being configured so as to be of a
mesh-like or texture-like structure.
* * * * *