U.S. patent application number 11/464317 was filed with the patent office on 2006-12-21 for method of manufacturing organic electroluminescent display device and organic electroluminescent display device and display device equipped with organic electroluminescent display device.
This patent application is currently assigned to SEIKO EPSON CORPORATION. Invention is credited to Shinichi YOTSUYA.
Application Number | 20060284554 11/464317 |
Document ID | / |
Family ID | 33157226 |
Filed Date | 2006-12-21 |
United States Patent
Application |
20060284554 |
Kind Code |
A1 |
YOTSUYA; Shinichi |
December 21, 2006 |
METHOD OF MANUFACTURING ORGANIC ELECTROLUMINESCENT DISPLAY DEVICE
AND ORGANIC ELECTROLUMINESCENT DISPLAY DEVICE AND DISPLAY DEVICE
EQUIPPED WITH ORGANIC ELECTROLUMINESCENT DISPLAY DEVICE
Abstract
A method of manufacturing an organic electroluminescent display
device, an organic electroluminescent display device, and a display
device equipped with an organic electroluminescent display device
are provided that enable a microlens to be formed without affecting
an organic luminescent layer during the manufacturing process and
to easily manufacture an organic electroluminescent display device
with increased light output efficiency. According to the method, a
lens pattern corresponding to a microlens that refracts the light
from an organic luminescent layer is formed by performing
photolithography treatment on a first transparent resin film formed
on a substrate, and the microlens is formed by performing reflow
treatment on the lens pattern.
Inventors: |
YOTSUYA; Shinichi; (Suwa,
JP) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
SEIKO EPSON CORPORATION
4-1, Nishi-shinjuku 2-chome Shinjuku-ku
Tokyo
JP
|
Family ID: |
33157226 |
Appl. No.: |
11/464317 |
Filed: |
August 14, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10862189 |
Jun 4, 2004 |
|
|
|
11464317 |
Aug 14, 2006 |
|
|
|
Current U.S.
Class: |
313/506 ;
313/504 |
Current CPC
Class: |
H01L 51/5275 20130101;
H01L 27/3244 20130101 |
Class at
Publication: |
313/506 ;
313/504 |
International
Class: |
H01J 1/62 20060101
H01J001/62 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 6, 2003 |
JP |
2003-162687 |
Claims
1. An organic electroluminescent display device, comprising: a
transparent substrate; a switching element controlled by a first
electrode and a transparent second electrode intersecting in matrix
form; a surface emitting element wherein a light-emitting state of
an organic luminescent layer is controlled by the switching
element, the organic luminescent layer being provided between the
first electrode and the second electrode; and a microlens provided
between the substrate and the second electrode, the microlens
having a convex curved surface facing the second substrate.
2. The organic electroluminescent display device according to claim
1, wherein a diameter of the microlens is from 1 .mu.m to 50
.mu.m.
3. The organic electroluminescent display device according to claim
1, wherein for each organic luminescent layer a plurality of
corresponding microlenses is provided.
4. The organic electroluminescent display device according to claim
1, wherein the refractive index of the microlens is from about 1.5
to about 1.8, and the refractive index of the second transparent
resin is from about 1.2 to less than about 1.5.
5. A display device equipped with an organic electroluminescent
display device that makes a display through a light-emitting state
of a plurality of organic luminescent layers, the organic
electroluminescent display device comprising: a transparent
substrate; a switching element controlled by a first electrode and
a transparent second electrode intersecting in matrix form; a
surface emitting element wherein a state of the organic luminescent
layers is controlled by the switching element, the organic
luminescent layers being provided between the first electrode and
the second electrode; and a microlens having a convex curved
surface facing the second electrode, the microlens being provided
between the substrate and the second electrode.
Description
RELATED APPLICATIONS
[0001] This application is a divisional patent application of U.S.
Ser. No. 10/862,189 filed Jun. 4, 2004, claiming priority to
Japanese Patent Application No. 2003-162687 filed Jun. 6, 2003, all
of which are hereby incorporated by reference.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The present invention relates to a method of manufacturing
an organic electroluminescent display device, an organic
electroluminescent display device, and a display device equipped
with an organic electroluminescent display device, the organic
electroluminescent display device making a display through the
light-emitting state of a plurality of organic luminescent
layers.
[0004] 2. Description of the Related Art
[0005] Current display devices can be classified into CRTs (Cathode
Ray Tubes) and flat display panels composed of various types of
elements. Flat display panels are light-weight and have a better
luminous efficiency than CRTs, and have been developed over the
years for use as monitor screens for computers, televisions and the
like. Recently, research is focusing on active matrix driven
organic EL (Electroluminescence) displays.
[0006] The organic EL display is of a configuration that sandwiches
a thin film including a fluorescent inorganic and organic compound
between a cathode and an anode, and the configuration has an array
of elements that are induced to emit light using the radiation of
light (fluorescence, phosphorescence) produced when excitons decay
that have been generated by recombination of electrons and holes
injected in the thin film. Such active matrix driven organic EL
displays are getting a lot of attention as they feature a thin
structure and high resolution.
[0007] FIG. 10 is a sectional view showing an example of a
configuration of an organic EL panel 101a included in a
conventional organic EL display.
[0008] The organic EL panel 101a has a configuration wherein a
light-emitting element 114 and a desiccant 109 are sealed through a
transparent glass 111 and a sealing glass 111a. In this organic EL
panel 101a, the space sealed by the glass 111 and the sealing glass
111a is desiccated by the desiccant 109, and light Lp emitted by a
light-emitting element 114 crosses the glass 111 and is emitted to
the outside.
[0009] With surface emitting elements such as the organic panel
101a, a problem is encountered in that light is lost and thus the
light output efficiency is poor, as the light Lp from the pixel
including the light-emitting element 114 is diffused in all
directions and light Lu, having an angle exceeding the critical
angle with regard to the surface of the glass 111, cannot be
emitted to the outside of the glass 111 due to a total reflection
phenomenon.
[0010] Conventionally, to solve such problems, organic EL
light-emitting devices of a configuration such as the one shown in
Japanese unexamined patent application publication 10-172756 have
been known.
[0011] Such a conventional organic EL light-emitting device uses a
configuration, wherein a microlens 2 is located inside a light
transmissive base board 1 as shown in FIG. 1 appended to the patent
application publication, a microlens 22 is located inside a light
transmissive base board 21 as shown in FIG. 2, microlenses 32 and
33 are located inside a light transmissive base board 31 as shown
in FIG. 3. However, with such a conventional configuration, it is
difficult and thus costly to place the microlens 2 inside the light
transmissive base board 1.
[0012] Further, in FIG. 4 of unexamined patent application
publication H10-172756, a configuration is used wherein a microlens
42 is provided inside a backing layer 43 that is formed on a light
transmissive base board 41.
[0013] An organic EL light-emitting device 40 has a configuration
wherein the microlens inside the backing layer 43 has a convex
curved surface formed on the side of the light transmissive base
board 41 rather than on the side of the lower electrode 44a.
[0014] In the organic EL light-emitting device 40 of such a
configuration, when comparing it to an organic EL light-emitting
device 10 shown in FIG. 1 and others, the difficulty with
manufacturing is seemingly resolved because the microlens 42 is not
formed inside the light transmissive base board 41 anymore.
[0015] However, in such an organic EL light-emitting device 40, as
the microlens 42 inside the backing layer 43 has a convex curved
surface formed on the side of the translucent substrate 41, a
problem exists in that, when the light from a light-emitting layer
44b that is provided between an opposed electrode 44c and the lower
electrode 44a is refracted, the margin of the critical angle is
small, at which the light ends up being reflected inside the
microlens 42 instead of being transmitted through the light
transmissive base board 41.
[0016] Further, in unexamined patent application publication
H10-172756, no concrete manufacturing procedure is disclosed
regarding the organic EL light-emitting device 40 shown in FIG. 4.
Further, for the active matrix driven organic EL light-emitting
device 40, the manufacturing seems problematical, as the substrate
process becomes a high temperature process of about 500 degrees
that requires the microlens 42 itself to be able to withstand such
high temperatures.
[0017] Here, the present invention is intended to solve the
above-mentioned issue by providing a method of manufacturing an
organic electroluminescent display device, an organic
electroluminescent display device, and a display device equipped
with an organic electroluminescent display device that enable a
microlens to be formed without affecting an organic luminescent
layer during the manufacturing process, and to easily manufacture
an organic electroluminescent display device with increased light
output efficiency.
SUMMARY
[0018] A first aspect of the present invention solves the above
issue by providing a method of manufacturing an organic
electroluminescent display device having a surface emitting element
that includes:
[0019] forming a switching element for controlling the
light-emitting state of an organic luminescent layer on a
transparent substrate,
[0020] forming a lens pattern corresponding to a microlens that
refracts the light from the organic luminescent layer by performing
photolithography treatment on a first transparent resin film that
has been formed on the substrate, followed by performing reflow
treatment on the lens pattern so as to form the microlens,
[0021] accumulating a second transparent resin having a lower
refractive index than the first transparent resin so as to cover
the microlens and then hardening the second transparent resin,
[0022] forming a second electrode on the second transparent
resin,
[0023] forming the organic luminescent layer on the second
electrode, and
[0024] forming a first electrode on the organic luminescent
layer.
[0025] Thus an organic electroluminescent display device having a
surface emitting element in which the light-emitting state of the
organic luminescent layer, provided between the first electrode and
the second electrode that is transparent intersecting in matrix
form, is controlled by a switching element controlled by the first
and second electrodes is manufactured.
[0026] With the above configuration, the microlens can be easily
formed by performing photolithography and reflow treatment on the
first transparent resin formed on the substrate by film forming
before the organic luminescent layer is formed. Therefore,
adversely affecting the heat-sensitive organic luminescent layer
can be avoided when forming the microlens.
[0027] According to a second aspect of the invention in addition to
the configuration of the first aspect, when accumulating and
hardening, the hardening is carried out while pressing a flat
substrate against the second transparent resin which has been
accumulated.
[0028] In this configuration, the flatness of the surface of the
accumulated second transparent resin is increased by pressing a
flat substrate against it. Thus, the light output efficiency can be
increased by avoiding a situation wherein the light emitted from
the organic luminescent layer is affected by the interface between
the second transparent resin and the second electrode that is also
transparent.
[0029] According to a third aspect of the invention in addition to
the configuration of either one of the first or second aspects,
when forming the microlens, a film is formed of the second
transparent resin on the substrate by spin coating.
[0030] This configuration enables easy film formation of the second
transparent resin on the substrate.
[0031] According to a fourth aspect of the invention in addition to
the configuration of any one of the first through third aspects,
when forming the microlens, the first transparent resin is formed
so as to have a convex curved surface on the side of (i.e., facing)
the second electrode.
[0032] With such a configuration, it becomes less likely for the
light generated from the organic luminescent layer to exceed the
critical angle at which the light will be reflected without
crossing the microlens in the case of crossing the convex curved
surface form microlens on the side of the second transparent resin
as compared to the case of crossing the convex curved surface form
microlens on the side of the substrate. Therefore, forming the
convex curved surface form microlens on the side of the second
transparent resin leads to an increased output efficiency of light
generated by the organic luminescent layer, thus enabling the
manufacture of an organic electroluminescent display device with
reduced electrical power consumption.
[0033] A fifth aspect of the invention is achieved by an organic
electroluminescent display device that includes:
[0034] a transparent substrate,
[0035] a switching element controlled by a first electrode and a
second electrode that is transparent intersecting in matrix
form,
[0036] a surface emitting element wherein an organic luminescent
layer is provided between the first electrode and the second
electrode, and the light-emitting state of the organic luminescent
layer is controlled by the switching element, and
[0037] a microlens provided between the substrate and the second
electrode, having a convex curved surface form on the side of the
second substrate.
[0038] With such a configuration, it becomes less likely for the
light generated from the organic luminescent layer to exceed the
critical angle at which the light will be reflected without
crossing the microlens in the case of crossing the convex curved
surface form microlens on the side of the second substrate as
compared to the case of crossing the convex curved surface form
microlens on the side of the substrate. Therefore, forming the
convex curved surface form microlens on the side of the second
substrate will lead to an increased output efficiency of light
generated by the organic luminescent layer and the electrical power
consumption of the organic electroluminescent display device can be
decreased.
[0039] According to a sixth aspect of the invention in addition to
the configuration of the fifth aspect, the diameter of the
microlens is from 1 .mu.m to 50 .mu.m.
[0040] With this configuration, the height of the completed
microlens can be reduced, and the distance between each center of
curvature of the lens and the light-emitting part can be made to
approach each other, and the efficiency thus increases
considerably. A diameter of the microlens of 1 .mu.m to 50 .mu.m is
preferred. If the diameter of the microlens is less than 1 .mu.m,
the optical focal power decreases due to a diffraction phenomenon,
and if the diameter of the microlens is more than 50 .mu.m, the
distance between the microlens and the light-emitting part is too
close compared to the focal distance, and thus a problem arises in
that the loss of light increases as not all of the light scattered
in all directions can be refracted above the critical angle.
Further, when therefore forming the light-emitting part in a spaced
apart position, close to the focal distance, not all of the light
scattered in all directions can be made to enter the microlens that
is directly below the light-emitting part, and some will enter the
microlens of a different light-emitting part, thereby creating the
risk of inducing a crosstalk phenomenon. Therefore, by choosing an
optimal microlens diameter of 1 .mu.m to 50 .mu.m, an organic
electroluminescent display device can be achieved with a minimum
loss of light.
[0041] According to a seventh aspect of the invention in addition
to the configuration of either one of the fifth or sixth aspects, a
plurality of microlenses is provided corresponding to each organic
luminescent layer.
[0042] Due to the existence of a plurality of microlenses with this
configuration, the light output efficiency of the light from each
organic luminescent layer increases, and thus the luminance
increases.
[0043] According to an eighth aspect of the invention in addition
to the configuration of any one of the fifth to seventh aspects,
the refractive index of the microlens is from 1.5 to 1.8, and the
refractive index of the second transparent resin is from 1.2 to
less than 1.5.
[0044] With such a configuration, the power of the microlens can be
enforced by choosing a large difference in refractive index, and
all of the light scattered in all directions can be refracted above
the critical angle, and thus an organic electroluminescent display
device can be achieved with a minimum loss of light.
[0045] A ninth aspect of the invention is achieved through a
display device equipped with an organic electroluminescent display
device that makes a display through the light-emitting state of a
plurality of organic luminescent layers, the organic
electroluminescent display device including:
[0046] a transparent substrate,
[0047] a switching element controlled by a first electrode and a
second electrode that is transparent intersecting in matrix
form,
[0048] a surface emitting element wherein the state of the organic
luminescent layers is controlled by the switching element, the
organic luminescent layers being provided between the first
electrode and the second electrode, and
[0049] a microlens having a convex curved surface form on the side
of the second electrode, the microlens being provided between the
substrate and the second electrode.
[0050] With this configuration, it becomes less likely for the
light generated from the organic luminescent layers to exceed the
critical angle at which the light will be reflected without
crossing the microlens in the case of crossing the convex curved
surface form microlens on the side of a second transparent resin as
compared to the case of crossing the convex curved surface form
microlens on the side of the substrate. Therefore, forming the
convex curved surface form microlens on the side of the second
transparent resin leads to an increased output efficiency of light
generated by the organic luminescent layers, and thus the
electrical power consumption of the display device equipped with
the organic electroluminescent display can be decreased.
BRIEF DESCRIPTION OF THE DRAWINGS
[0051] FIG. 1 is a sectional view showing an example of a
configuration of an organic electroluminescent (EL) panel in
accordance with an embodiment of the invention.
[0052] FIGS. 2a and b are sectional views showing an example of a
sequence of the manufacturing method of the organic EL panel.
[0053] FIGS. 3a and b are sectional views showing an example of a
sequence of the manufacturing method of the organic EL panel.
[0054] FIGS. 4a and b are sectional views showing an example of a
sequence of the manufacturing method of the organic EL panel.
[0055] FIGS. 5a and b are sectional views showing an example of a
sequence of the manufacturing method of the organic EL panel.
[0056] FIG. 6 is a sectional view showing an example of a sequence
of the manufacturing method of the organic EL panel.
[0057] FIG. 7 is a sectional view showing an example of a sequence
of the manufacturing method of the organic EL panel.
[0058] FIG. 8 is a sectional view showing an example of an
application of the organic EL panel in accordance with the present
embodiment.
[0059] FIG. 9 is a sectional view showing an example of an
application of the organic EL panel in accordance with the present
embodiment.
[0060] FIG. 10 is a sectional view showing an example of a
conventional configuration of an organic EL panel.
DETAILED DESCRIPTION
[0061] Following is an explanation of a preferred embodiment with
reference to the drawings.
[0062] FIG. 1 is a sectional view showing an example of a
configuration of an organic electroluminescent (EL) panel 1 to
which an organic electroluminescent display device as a preferred
embodiment of the present invention is applied.
[0063] The organic EL panel 1 is to be mounted to a display device,
and includes a substrate 11, a microlens 17, a low refractive index
resin 5, a transistor 12, a wiring 7, an insulating layer 9, an
anode 15, an organic luminescent layer 14, and a cathode 13. This
organic EL panel 1 is a sealant substrate light-emitting organic EL
panel that emits light from the surface of the substrate 11 towards
the outside (lower part of the drawing).
[0064] The substrate 11 is a transparent substrate like a glass
plate. On this substrate, the low refractive index resin 5 is
provided. In the inner part of this low refractive index resin 5, a
microlens array composed of an array of more than one microlens 17
is formed. Further, in the inner part of this low refractive index
resin 5, the transistor 12, the wiring 7 and an opening part 16a
that extends from the anode 15 are provided.
[0065] The microlens 17 is composed of a transparent resin with a
high refractive index, for example the refractive index (nD) being
from 1.5 to 1.8. On the other side, the low refractive index resin
5 consists of a resin with a low refractive index, for example this
refractive index (nD) being from 1.2 to less than 1.5. It is
preferable for the refractive index (nD) of the microlens 17 to be
1.5 or more, because the larger the difference between the
refractive index of the low refractive index resin 5 and the
microlens 17, the stronger the power of the microlens, and thereby
refracting all of the light scattered in all directions above the
critical angle, an organic EL panel 1 can be achieved with a
minimum loss of light. If it is less than 1.5, there is a risk of a
total reflection phenomenon occurring at the interface with the
refractive index (nD) of the substrate 11 being for example
1.5.
[0066] Further, it is preferable for the refractive index of the
microlens 17 to be 1.8 or less, because the refractive index of the
microlens 17 exceeding 1.8 leads to a combination where the
difference in refractive index exceeds 0.6 to the one of the low
refractive index resin 5. In that combination there is a risk that
the reflection at the interface gets too large and the light output
efficiency thus decreases.
[0067] On the other hand, it is preferable for the refractive index
of the low refractive index resin 5 to be 1.2 or more, as it
otherwise leads to a combination where the difference in refractive
index exceeds 0.6 to the one of the microlens 17. In that
combination there is a risk that the reflection at the interface
gets too large and the light output efficiency thus decreases.
Further, it is preferable for the refractive index of the low
refractive index resin 5 to be less than 1.5, as it otherwise leads
to a combination where the difference in refractive index falls
below 0.1 to the one of the microlens 17. In that combination the
power of the microlens weakens, and not all of the light scattered
in all directions can be refracted above the critical angle,
leading to an organic EL panel 1 with a large loss of light.
[0068] With such a configuration, all of the light scattered in all
directions can be refracted above the critical angle, and the
organic EL panel 1 can be achieved with a minimum loss of
light.
[0069] Further, the diameter of the microlens 17 is preferably from
1 .mu.m to 50 .mu.m. It is preferable for the diameter of the
microlens 17 to be 1 .mu.m or more, as otherwise due to a
diffraction phenomenon of the light the optical focal power
decreases and the focal power becomes small.
[0070] Further, it is preferable for the diameter of the microlens
17 to be 50 .mu.m or less, because when the diameter of the
microlens exceeds 50 .mu.m, the distance between the light-emitting
part and the microlens 17 is too close compared with the focal
distance, and therefore not all of the light scattered in all
directions can be refracted above the critical angle, leading to an
increase in negative influences such as an increased loss of light.
Further, when therefore forming the light-emitting part in a
position apart, close to the focal distance, not all of the light
scattered in all directions can be made to enter the microlens that
is directly below the light-emitting part, and some will enter the
microlens 17 of a different light-emitting part, thereby creating
the risk of inducing a crosstalk phenomenon.
[0071] With such a configuration, the organic EL panel 1 can be
achieved with a minimum loss of light by choosing the optimum
diameter of the microlens 17 to be 1 .mu.m to 50 .mu.m.
[0072] On this low refractive index resin 5, the cathode 13, the
organic luminescent layer 14 and the anode 15 are provided. The
cathode 13, the organic luminescent layer 14 and the anode 15
compose an organic EL element. The cathode 13, the organic
luminescent layer 14 and the anode 15 are provided on the low
refractive index resin 5 in a plurality, each set composing a pixel
3. Further, on the substrate 11 the transistor 12 is provided as a
switching element that is controlled by the cathode 13 and the
anode 15 intersecting in the form of a matrix.
[0073] This transistor 12 has the function to control the
light-emitting state of the organic luminescent layer 14 that is
provided between the cathode 13 and the anode 15. That is to say,
this transistor 12 has the function to actively drive the organic
EL element that includes the organic luminescent layer 14 and the
like. Further, to insulate the organic luminescent layer 14 from
another organic luminescent layer 14 on the low refractive index
resin 5 the insulating layer 9 is provided.
[0074] To each organic luminescent layer 14 at least one associated
microlens 17 is provided. In the present embodiment, more than one
microlens 17 is provided to each organic luminescent layer 14. With
such a configuration, due to the existence of more than one
microlens 17, the efficiency of the light output and the luminance
of the light from each organic luminescent layer 14 improves.
[0075] The pitch of this microlens array 17 is preferably within a
range of for example 1 to 100 .mu.m. With such a configuration,
each pixel 3 can be covered with a microlens array (MLA) composed
of more than one microlens 17, and thus the height of the microlens
17 can be kept low. Further, as the gap between the organic
luminescent layer 14 and the microlens array can be filled in the
organic EL panel 1, a high contrast picture can be achieved with no
crosstalk between more than one pixel 3 that can be caused when the
light emitted from each pixel 3 is mixed and then condensed by the
microlens 17.
[0076] Characteristic in the present embodiment is that the
microlens 17 is for example provided between the anode 15 and the
substrate 11. Furthermore a characteristic in the present
embodiment is that as mentioned above, the microlens 17 has for
example on the side of the anode 15 a convex curved surface form.
With such a configuration, it becomes less likely for the light
generated from the organic luminescent layer 14 to exceed the
critical angle at which the light will be reflected without
crossing the microlens 17 in the case of crossing the convex curved
surface form microlens 17 on the side of the anode 15 as compared
to the case of crossing the convex curved surface form microlens 17
on the side of the substrate 11. Therefore, forming the convex
curved surface form microlens 17 on the side of the anode 15 will
lead to an increased output efficiency of light generated by the
organic luminescent layer 14 and the organic EL panel 1 with
reduced electrical power consumption can be composed.
[0077] The organic EL panel 1 being of the above configuration, an
explanation follows of an example of the behavior of the organic EL
panel 1.
[0078] In this organic EL panel 1, each organic EL element is
driven by the active matrix drive. Concretely, in each organic EL
element, the cathode 13 and the anode 15 compose a matrix
structure, and by applying a voltage between the cathode 13 and the
anode 15 corresponding to the pixel 3 that is selected, the
transistor 12 is controlled, and due to the operation of the
transistor 12, a current will flow in the organic luminescent layer
14 that is provided between the cathode 13 and the anode 15, thus
inducing the organic luminescent layer 14 to emit light.
[0079] The light generated by the organic luminescent layer 14
crosses the anode 15 that is transparent and the low refractive
index resin 5 that has a low refractive index, and enters the
microlens 17. As the microlens 17 has a higher refractive index
than the low refractive index resin 5, the light generated by the
organic luminescent layer 14 is refracted, crosses the substrate 11
and is emitted to the outside part of the organic EL panel 1. At
this instant, as the microlens 17 is of a convex curved surface
form on the side of the anode 15, the light from the organic
luminescent layer 14 can cross the substrate 11 efficiently without
being affected by the critical angle of the microlens 17.
[0080] Therefore, not only can the efficiency of the light output
and the luminance of the light from the organic luminescent layer
14 be increased for the organic EL panel 1, the power consumption
can be decreased at a luminance that is the same as conventional
luminance.
[0081] This concludes the above example of the behavior of the
organic EL panel 1. An explanation now follows of an example of the
steps of the procedure of the manufacturing method of the organic
EL panel 1.
[0082] FIGS. 2 to 7 are sectional views showing an example of a
process of the manufacturing method of the organic EL panel 1 shown
in FIG. 1.
[0083] Forming the switching element etc.
[0084] First, as shown in FIG. 2 (a), the transparent substrate 11
of a non-alkali glass material for example is prepared. On this
substrate 11, the wiring 7 constituting the circuit, the transistor
12 being for example a polycrystalline silicon thin film
transistor, a condenser and the like are formed.
[0085] Forming the microlens
[0086] As shown in FIG. 2 (b), on the substrate 11 onto which the
transistor 12 and the like have been formed, a film is formed of a
resin (photosensitive high refractive index resin 17a) as a base
material for forming the microlens 17. As this photosensitive high
refractive index resin 17a, for example MFR-344H made by JRS with a
refractive index (nD) of 1.62 is used. Further, as a method of
forming the film of the photosensitive high refractive index resin
17a, for example spin coating is used. The film of the
photosensitive high refractive index resin 17a that is formed by
spin coating is coated with a film thickness of 3.0 .mu.m for
example. And, a lens pattern smaller than the pixel 3 is formed of
about 33 .mu.m square by applying photolithography technology
against the photosensitive high refractive index resin 17a formed
on the substrate 11 in such a way.
[0087] The substrate 11 onto which a lens pattern as shown in FIG.
2 (b) has been formed is then processed by reflow treatment by
putting it into a clean oven at 180 degrees for 30 minutes for
example, and a lens form as shown in FIG. 3 (a) is formed
corresponding to the form of the microlens 17 that refracts the
light from the organic luminescent layer 14.
[0088] Resin Accumulating and Hardening
[0089] Next, an acrylic resin with a refractive index of about 1.38
is applied by spin coating and the like onto the surface of the
substrate 11 on which among others the microlens 17 are formed, and
by putting it into a clean oven with an atmosphere of about 180
degrees for about 30 minutes the surface of this acrylic resin is
caused to reflow, and planarization is carried out as in the low
reflective index resin 5 shown in FIG. 3 (b). The planarized low
refractive index resin 5 is composed so as to cover the microlens
17 and the like formed on the substrate 11.
[0090] Forming the Second Electrode
[0091] On this surface of the low refractive index resin 5 composed
in such a way, a resist (not shown) is coated, and by dry etching
using oxygen for example, the opening part 16a is formed in a
desired part as shown in FIG. 4 (a).
[0092] In part of the surface of the low refractive index resin 5
including this opening part 16a, a film of about 100 nm including
for example mainly indium tin oxide (ITO) is formed by sputtering
as shown in FIG. 4 (b), and, patterning of the anode 15
corresponding to the anode 15 of the pixel 3 is carried out by
photolithography technology.
[0093] Furthermore, by forming a film of silicon oxide and the like
at the connection of each anode 15 to the others, as shown in FIG.
5 (a), the insulating layer 9 is formed. By forming the insulating
layer 9, the division of the pixel 3 becomes definite.
[0094] Forming the Luminescent Layer
[0095] Next, as shown in FIG. 5 (b), the organic luminescent layer
14 is formed on the anode 15 by evaporation for example.
[0096] Forming the First Electrode
[0097] Next, as shown in FIG. 6, the cathode 13 is formed on the
organic luminescent layer 14 and the insulating layer 9. Next,
though not shown, defined sealing is carried out, and as shown in
FIG. 1, the active matrix driven organic EL panel 1 having the
microlens 17 is completed.
[0098] According to a preferred embodiment of the present
invention, with the organic EL panel 1 having a microlens array
completed in this way, compared with organic EL panels without a
microlens array, about twice the luminance can be achieved by
applying an identical driving voltage, and also the luminance
efficiency is about double. Further, with such a manufacturing
method of the organic EL panel 1, the microlens 17 can be easily
formed by performing photolithography treatment and reflow
treatment on the photosensitive high refractive index resin 17a, as
shown in FIG. 2 (b), before forming the organic luminescent layer
14.
[0099] Therefore, the possibility that the organic luminescent
layer 14 (which is sensitive to heat) is negatively affected when
forming the microlens 17 of FIG. 1 can be avoided. Further, not
only can the luminance efficiency be increased for the organic EL
panel 1 having a microlens array including the microlens 17, but
having a microlens 17 having a convex curved surface form on the
side of the anode 15 results in an increase of the margin of the
critical angle at which the light from the organic luminescent
layer 14 is reflected by the microlens 17, and thus, the output
efficiency of light can be further improved. Therefore, at a
luminance that is the same as that of conventional organic EL
panels, with lower power consumption than conventionally, the
luminous lifetime can be lengthened. Consequently, an advantage
such as the above-mentioned can be also obtained for a display
device equipped with the organic EL panel 1.
[0100] Further, in the above embodiment, as shown in FIG. 3 (a),
when forming the low refractive index resin 5 on the substrate 11
onto which the microlens 17 and the like are formed, the
planarization is carried out by causing reflow at a set
temperature, after applying an acrylic resin by spin coating as a
base material to the low refractive index resin 5 composing the
same. Planarization, though, may also be carried out by a method
such as the one described in the following.
[0101] Concretely, as shown in FIG. 7, on the substrate 11 onto
which the microlens 17 and the like are formed, an acrylic resin
with a refractive index of 1.38 for example is applied as the low
refractive index resin 5. As such an acrylic resin, World Rock No.
7702 produced by Kyoritsu Chemical can be used for example. The
acrylic resin applied onto the substrate 11, as shown in FIG. 7,
then undergoes an adhesion and hardening process to hold a quartz
substrate (glass substrate) 4 of a thickness of for example 3
mm.
[0102] It is then preferable to perform a water repellency
treatment on the surface of the quartz substrate 4. As a method for
performing such a water repellency treatment on the surface of the
quartz substrate 4, a silane coupling agent and the like such as
HMDS (hexamethyldisilazane) is adequate. Alternatively, plasma
deposition by CF gas can be given as an example.
[0103] Next, the quartz substrate 4 is exfoliated, and as shown in
FIG. 3 (b), the surface of the low refractive index resin 5
undergoes planarization. As the quartz substrate 4 undergoes water
repellency treatment, the adhesion force of the low refractive
index resin 5 of being originally adhesive for example is reduced
almost to zero, and the quartz substrate 4 can be exfoliated
easily. Taking over the smooth surface form of the quartz substrate
4, the surface of the low refractive index resin 5 from which the
quartz substrate 4 has been exfoliated can be made to be smooth.
Into the low refractive index resin 5 that has undergone such
smoothing, the opening part 16a is formed in a designated location
as shown in FIG. 4 (a).
[0104] The present invention is not limited by the above-mentioned
embodiment, and various modifications can be made within the scope
of the Claims. For example, in each of the above configurations of
the embodiment, parts can be omitted and arbitrarily combined to
differ from the above. Further, in the above embodiment, a silicon
oxide film of for example 60 nm may be inserted between the low
refractive index resin 5 and the anode 15. With such a
configuration, the adhesion can be improved between the low
refractive index resin 5 and the anode 15.
[0105] Further, in the above embodiment, the organic EL panel 1 is
explained as using a low-molecular organic EL element for example,
but, as shown in FIG. 8, a high-molecular organic EL element can
also be used to obtain the same effect. For example, when
manufacturing a full color panel, the high-molecular organic EL
material can be selectively applied as a liquid by using an inkjet
process. Therefore, if a wall called a bank is formed on the panel
between pixels to separate each pixel from the others, so that the
liquid does not flow to the other pixels, a panel can be
manufactured just as the low-molecular organic EL.
[0106] Further, the above embodiment is not limited to a
configuration of an organic EL panel 1a as shown in FIG. 8, but can
also be applied to an effective organic EL panel 1b shown in FIG.
9.
[0107] This organic EL panel 1b uses practically the same processes
as the above-mentioned processes, and in addition to the
configuration of the organic EL panel 1a shown in FIG. 8, color
filter layers 2B, 2R, 2G are formed by color filter resist between
the low refractive index resin 5 and the anode 15. With such a
configuration, a full color display device can be achieved that
uses an organic EL panel emitting white light.
* * * * *