JPH09101493A - Manufacturing method of liquid crystal display element - Google Patents

Abstract

(57) [Abstract] [Problem] To prevent display unevenness as much as possible. SOLUTION: A step of forming an electrode 3 and an alignment film 4 on a transparent substrate 2, a step of forming a mixed layer of a spacer 6 and a photoresist 7 on a substrate 1 on which the alignment film is formed, The method is characterized by comprising a step of pressurizing and exposing the mixed layer so that the film thickness becomes substantially equal to the diameter of the spacer, and a step of developing the mixed layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing a liquid crystal display device.

[0002]

2. Description of the Related Art In recent years, liquid crystal display elements, which have the advantages of thinness, light weight, and low power consumption, have been actively used as display devices for personal OA equipment such as Japanese word processors and desktop personal computers. Along with the widespread use of the liquid crystal display devices, the demands for large screens, high definition, high contrast and high display quality of liquid crystal display devices are increasing. As the liquid crystal display device has a larger screen and higher definition, it becomes more difficult to realize high contrast and high display quality. One of the causes for this is that it becomes difficult to keep the thickness of the liquid crystal layer uniform over the entire surface as the area increases, and the unevenness of the thickness of the liquid crystal layer increases.

FIG. 5 shows a general structure of a conventional liquid crystal display device. The liquid crystal display element shown in FIG. 5 is a liquid crystal display element of a simple Matrices driving system, and includes a scanning electrode substrate 1, a signal electrode substrate 11, a liquid crystal composition 24 sealed between these substrates, and a gap between the substrates. And a spacer 6 for keeping the above constant.

The scanning electrode substrate 1 is formed as follows.
First, ITO (Indium Tin Oxid) is formed on the transparent glass substrate 2.
e) A film-shaped scanning electrode 3 is formed by depositing and patterning a film. Then, the alignment film 4 is deposited on the main surface of the glass substrate 2 (the surface on which the scanning electrodes 3 are formed), and a rubbing process is performed to complete the scanning electrode substrate 1.

On the other hand, the signal electrode substrate 11 is formed as follows. First, an ITO film is deposited on a transparent glass substrate 12 and patterned to form a strip-shaped signal electrode 13.
Then, the main surface of the glass substrate 12 (the signal electrode 13
The alignment film 14 is deposited on the surface on which the signal electrodes are formed, and a rubbing process is performed to complete the signal electrode substrate 11.

A plurality of spherical spacers 6 are dispersed on one of the two substrates 1 and 11, for example, the scanning electrode substrate 1, and a thermosetting sealant 21 is printed on the other substrate 11. To do. At this time, an injection port (not shown) is provided in the printed sealant so that liquid crystal can be injected later.

Subsequently, the substrate 1 and the substrate 11 are attached to each other so that the scanning electrode 3 and the signal electrode 13 are orthogonal to each other, pressed and heated, and the sealant 21 is hardened to fix the substrate 1 and the substrate 11.

Next, the liquid crystal composition 24 is injected into the gap between the substrate 1 and the substrate 11 through the injection port, and after the injection, the injection port is sealed with an ultraviolet curable resin. Thereby, the liquid crystal display element is completed.

In the liquid crystal display device manufactured as described above, the spacers 6 cannot be evenly dispersed to cause unevenness, the spacer 6 reduces the contrast of the display screen, and minute spots due to aggregation of the spacers 6. Has occurred on the display screen, resulting in a significant decrease in display performance.

In order to solve this problem, a method has been proposed in which a resin such as a photoresist is applied before or after the spacers 6 are scattered to selectively fix the spacers 6 at desired positions at a required density. .

[0011]

As described above, the liquid crystal display device manufactured by the method of selectively fixing the spacers 6 at a desired position with a required density has a problem that the accuracy of the substrate gap becomes poor. . This problem will be described with reference to FIG.

The state of the spacer 6 and the photoresist layer 7 which may occur when the spacer 6 is sprayed after the photoresist layer 7 is applied to the substrate (not shown) is shown in FIG.
The state of the spacer 6 and the photoresist layer 7 shown in (b) which can occur when the photoresist layer 7 is applied after the spacer 6 is sprayed on the substrate or when the mixture of the spacer 6 and the photoresist layer 7 is applied to the substrate. Figure 6
(C) and (d) show.

Here, the diameter of the spacer 6 (desired substrate gap)
Is d ₁ and the film thickness of the photoresist layer 7 is d ₂ .
In the case of the state shown in FIGS. 6A and 6C, a desired substrate gap d ₁ can be obtained. However, FIG.
In the case of the state shown in (b) and FIG. 6 (d), the film thickness of the liquid crystal layer, that is, the substrate gap becomes larger than the desired value d ₁ , resulting in display unevenness.

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a liquid crystal display device capable of preventing display unevenness as much as possible.

[0015]

A first aspect of a method of manufacturing a liquid crystal display device according to the present invention comprises a step of forming an electrode and an alignment film on a transparent substrate, and a step of forming the electrode and the alignment film on the substrate on which the alignment film is formed. A step of forming a mixed layer of spacers and a photoresist; a step of pressurizing and exposing the mixed layer so that a film thickness of the photoresist is approximately equal to a diameter of the spacer; and a step of developing the mixed layer. , Are provided.

The second aspect of the manufacturing method of the present invention is the first aspect.
In the liquid crystal display element of the aspect, the mixed layer is pressed,
The step of exposing is characterized in that a photomask is provided on the mixed layer, and the photomask is exposed under pressure.

The third aspect of the manufacturing method of the present invention is the second aspect.
In the manufacturing method of the above aspect, an adhesion preventive layer is provided between the mixed layer and the photomask to prevent the mixed layer and the photomask from adhering to each other.

The fourth aspect of the manufacturing method of the present invention is the first aspect.
In the manufacturing method of the aspect, in the step of pressurizing and exposing the mixed layer, the mixed layer is pressed and then exposed using a photomask.

The fifth aspect of the manufacturing method of the present invention is the first aspect.
In the manufacturing method of the above aspect, the step of forming the mixed layer on the substrate is performed using a dry film photoresist.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of a method for manufacturing a liquid crystal display device according to the present invention will be described with reference to FIGS.

The manufacturing method of this embodiment is a manufacturing method of a STN type liquid crystal display element of a simple matrix drive system, and the manufacturing process is shown in FIG. 1, and the liquid crystal display element manufactured by the manufacturing method of this embodiment is shown. Figure 2 is a cross-sectional view of the configuration of
Shown in

The scanning electrode substrate 1 forming the liquid crystal cell is formed as follows. First, a color filter layer (not shown) made of RGB is formed on the surface of a transparent substrate 2 made of soda lime glass having SiO _x as a main component and having a thickness of 1.1 mm, for example, and then the color filter layer is covered. For example, a protective layer (not shown) made of acrylic resin is formed.
Then, an ITO film is vapor-deposited on this protective layer and patterned to form a strip-shaped scanning electrode 3 composed of, for example, 640 scanning lines. At this time, the width of the strip-shaped scanning lines in the display area is 0.27 mm, and the scanning line interval is 0.0
It is 3 mm. Then, after depositing a film made of polyimide so as to cover the scanning electrodes 3, a rubbing process is performed to form an alignment film 4.

On the other hand, in the signal electrode substrate 11, an ITO film is vapor-deposited on the surface of a transparent substrate 12 having a thickness of 1.1 mm, which is made of soda lime glass having SiO _x as a main component, and patterned to form 240 signal lines. The strip-shaped signal electrode 13 having the same is formed. At this time, the width of the signal line in the display area is, for example, 0.27 mm, and the signal line interval is 0.03 mm. Subsequently, after depositing a film made of polyimide so as to cover the signal electrode 13, a rubbing process is performed to form an alignment film 14.

The alignment film 4 and the alignment film 14 are rubbed so that the liquid crystal composition is twisted by 240 ° and aligned when the substrates 1 and 14 are opposed to each other.

Next, the scan electrode substrate 1 is subjected to the following processing. A resin spacer 6 having a particle size of 5 μm was dispersed on the substrate 1 on which the alignment film 4 was formed so that the density was 70 pieces / mm ^2, and then a photoresist was applied to a thickness of about 2000 Å to form a resist layer 7 Are formed (see FIG. 1A). Next, as shown in FIG. 1B, a transparent sheet layer 8 made of, for example, polyethylene terephthalate is formed on the resist layer 7. The sheet layer 8 is provided to prevent the mask 9 and the resist layer 7 which will be described later from adhering to each other at the time of pressurization, and may be omitted if there is no risk of the resist layer 7 and the mask 9 adhering to each other. .

Next, as shown in FIG. 1C, a photomask 9 is placed on the sheet layer 8 and an exposure process is performed while applying pressure so that the thickness of the resist layer 7 becomes substantially equal to the diameter of the spacer 6. . Subsequently, as shown in FIG. 1D, the photomask 9 and the sheet layer 8 are removed and then developed to expose the alignment film 4.

Next, the main surface of the signal electrode substrate 11 (alignment film 14
Epoxy resin adhesive 21 on the outer periphery of the
After printing except the area which will be the injection port of the liquid crystal composition,
The signal electrode substrate 11 and the scanning electrode substrate 1 are bonded together. Then, the liquid crystal composition 24 is injected from the injection port by using a vacuum injection method, and the injection port is sealed with an ultraviolet curable resin. Then, the scanning electrode substrate 1 and the signal electrode substrate 11
A liquid crystal display device is completed by providing a retardation plate and a polarizing plate (not shown) on the outer surface of the liquid crystal display device.

The liquid crystal display device thus obtained was subjected to multiplex drive using a drive voltage having a duty ratio of 1/240, and the display color was observed. As a result, a uniform display with no unevenness was obtained.

As described above, according to the manufacturing method of this embodiment, the resist layer 7 for fixing the spacer 6 is fixed.
Exposure is performed while applying pressure, so that the substrate
It becomes possible to make it equal to the diameter of, and it is possible to prevent display unevenness as much as possible.

Although the resist layer 7 is formed after the spacers 6 are dispersed in the manufacturing method of the above embodiment, the spacers 6 may be dispersed after the resist layer 7 is formed. Further, the spacer 6 has a volume concentration of, for example, 0.1%.
Needless to say, even if the dispersed resist is applied onto the substrate 1 on which the alignment film 4 is formed and the subsequent steps shown in FIG. 1B are performed, the same effect as that of the manufacturing method of the present embodiment can be obtained. Yes.

Further, in the manufacturing method of the present embodiment, although the spacers 6 and the resist layer 7 are formed on the scanning electrode substrate 1, they may be formed on the signal electrode substrate 11. In this case, the adhesive 21 is printed on the scanning electrode substrate 1.

Further, in the manufacturing method of the present embodiment,
Although the exposure of the resist layer 7 was performed during pressurization,
It is needless to say that the same effect can be obtained by performing exposure using a photomask after sufficiently pressurizing so that the thickness is substantially equal to the diameter of the spacer 6.

Next, a second embodiment of the method of manufacturing a liquid crystal display device according to the present invention will be described with reference to FIG. FIG. 3 is a sectional view of a liquid crystal display element manufactured by the manufacturing method according to the second embodiment. The manufacturing method of this embodiment is the same as the manufacturing method of the first embodiment shown in FIG.
The manufacturing method is the same as that of the first embodiment except that a photomask is used so that the resist layer 7 remains only in the non-pixel portion region. Since the liquid crystal display element manufactured by the manufacturing method of the second embodiment does not have the spacer 6 in the pixel area as shown in FIG. 3, the liquid crystal display manufactured by the manufacturing method of the first embodiment. The contrast ratio is superior to that of the device, and more uniform display is possible.

Next, a third embodiment of the method of manufacturing a liquid crystal display device according to the present invention will be described with reference to FIG. The manufacturing method of this embodiment uses a dry film photoresist. As shown in FIG. 4, the dry film photoresist 40 is a negative photoresist in which a photopolymer 41 in which a resin spacer 43 having a particle size of 5 μm is dispersed is sandwiched between polyolefin cover sheets 45 and 46.

First, the scanning electrode substrate 1 on which an alignment film (not shown) is formed is passed between rolls of a dry film laminator (not shown). Then, the polyolefin cover sheet 45 of the dry film photoresist 40 is peeled off and the dry film photoresist 40 is formed on the surface of the substrate 1.
Are bonded (see FIG. 4). At this time, the dry film photoresist 40 is pressed by the roll so that the thickness of the resist layer becomes substantially equal to the diameter of the resin spacer 43.

Subsequently, an exposure process is performed using a photomask (not shown), and then development is performed to expose the alignment film. As a result, the spacers are fixed on the substrate 1 by the resist as shown in FIG. The subsequent steps are performed in the same manner as in the case of the first embodiment to complete the liquid crystal display element.

As described above, the liquid crystal display element manufactured by the manufacturing method of this embodiment has no display unevenness like the liquid crystal display element manufactured by the manufacturing method of the first embodiment.

In the manufacturing method of the third embodiment, if a photomask that leaves the resist only in the non-display area when the photoresist is exposed is used, the liquid crystal display device obtained by this is obtained. Compared with the liquid crystal display element manufactured by the manufacturing method of the third embodiment, the contrast ratio is excellent and more uniform display is possible.

In the manufacturing methods of the first to third embodiments, resin spacers were used as spacers, but glass fiber spacers or silica spheres are more accurate than resin spacers. Therefore, the more uniform display can be obtained by using the glass fiber spacers or the silica spheres.

In the manufacturing methods of the first to third embodiments, the simple matrix driving type liquid crystal display element has been described as an example, but the present invention is also applicable to the manufacturing of the active matrix driving type liquid crystal display element. Needless to say, can be applied.

[0041]

As described above, according to the present invention, since the substrate gap can be set to a desired value, uniform display without display unevenness can be obtained.

[Brief description of the drawings]

FIG. 1 is a process sectional view showing a manufacturing process of a first embodiment of a method for manufacturing a liquid crystal display element according to the present invention.

FIG. 2 is a configuration cross-sectional view of a liquid crystal display element manufactured by the manufacturing method according to the first embodiment.

FIG. 3 is a cross-sectional view showing a configuration of a liquid crystal display element manufactured according to a second embodiment of the present invention.

FIG. 4 is a diagram illustrating a manufacturing process of a third embodiment of a method of manufacturing a liquid crystal display element according to the present invention.

FIG. 5 is a general configuration cross-sectional view of a simple matrix drive type liquid crystal display element.

FIG. 6 is an explanatory view illustrating a problem of the conventional manufacturing method.

[Explanation of symbols]

 1 Scanning Electrode Substrate 2 Glass Substrate 3 Scanning Electrode 4 Alignment Film 6 Spacer 7 Resist Layer 8 Sheet Layer 9 Photomask 11 Signal Electrode Substrate 12 Glass Substrate 13 Signal Electrode 14 Alignment Film 21 Adhesive 24 Liquid Crystal Composition 40 Dry Film Photoresist 41 Photopolymer 43 Spacer 45 Polyolefin cover sheet 46 Polyolefin cover sheet

Claims (5)

[Claims] 1. A step of forming an electrode and an alignment film on a transparent substrate, a step of forming a mixed layer of a spacer and a photoresist on the substrate having the alignment film formed thereon, and a film thickness of the photoresist. A method of manufacturing a liquid crystal display device, comprising: a step of exposing the mixed layer so as to have a diameter substantially equal to the diameter of the spacer; and a step of developing the mixed layer. 2. The liquid crystal display element according to claim 1, wherein in the step of exposing the mixed layer by applying pressure, a photomask is provided on the mixed layer and the exposure is performed while applying pressure to the photomask. Production method. 3. The liquid crystal display according to claim 2, wherein an adhesion preventing layer is provided between the mixed layer and the photomask in order to prevent the mixed layer and the photomask from adhering to each other. Device manufacturing method. 4. The method of manufacturing a liquid crystal display device according to claim 1, wherein in the step of pressurizing and exposing the mixed layer, the mixed layer is pressed and then exposed using a photomask. 5. The method of manufacturing a liquid crystal display device according to claim 1, wherein the step of forming the mixed layer on the substrate is performed using a dry film photoresist.