JPH08292440A - Production of liquid crystal display device - Google Patents

Abstract

PURPOSE: To simplify a working stage over the entire part by directly impressing a mask material to regions where a mask is formed in the case respective pixel regions are divided into plural regions and an oriented layer corresponding to one region among these regions is partially masked. CONSTITUTION: A lower substrate 51 is formed. The lower substrate 51 is washed and dried. The oriented layer 52 of polyimide is then uniformly formed at a thickness of about 850 angstrom on the lower substrate 51 by using an impressing method. The lower substrate 51 is passed under a roller 53, by which the oriented layer 52 is subjected to first rubbing. The mask material 54 is impressed on the regions of the respective upper halves of the respective pixels and thereafter, the second rubbing is executed in the V direction varying by 80 deg. as the first rubbing. A mask material 54 is then peeled by using an org. solvent, such as acetone.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a liquid crystal display device having a wide viewing angle.

[0002]

2. Description of the Related Art Liquid crystal display devices are characterized by being thin, lightweight, and consuming little power, and have been attracting attention as display devices for flat color televisions and the like. However, the liquid crystal display device has a property that its optical characteristics change depending on the angle of observation, and the viewing angle at which a good display can be obtained is limited. For this reason, several methods for widening the viewing angle have been proposed so far. One of them is a method called orientation division. For orientation division, each pixel is divided into, for example, 2
This is a method of dividing and changing the alignment direction of the liquid crystal for each of the two divided areas.

In the case of changing the alignment direction of the liquid crystal in one pixel by the orientation division, the following method is generally used. That is, an alignment layer is formed on the surface of a substrate on which a large number of pixels are formed, and the first rubbing process is performed in one direction on the entire surface of the alignment layer. Then, cover a part of each pixel with a mask, and in the direction opposite to the first rubbing from the top of the mask,
This is the method of rubbing the second time. At this time, the orientation direction is different between the portion covered with the mask and the portion not covered with the mask, and the pixels obtained by the orientation division are obtained.

In the case of forming the pixels whose orientation is divided as described above, a part of each pixel is covered with a mask before the second rubbing. As a method of forming such a mask, for example, Japanese Patent Laid-Open No. 56-138713.
There is a photolithography technique described in the publication.

Here, a method of dividing the orientation direction into two by using the photolithography technique will be described with reference to FIG.

First, an alignment layer 62 is formed on a substrate 61 on which a plurality of pixels are formed (FIG. A). Then, the surface of the alignment layer 62 is rubbed with the rotating cloth 63 to perform the first rubbing (FIG. B). Next, the substrate 61 is placed on a spinner (not shown), and a photoresist is appropriately applied onto the alignment layer 62. Then, the spinner is rotated, and the photoresist is applied to the entire surface of the alignment layer 62 and dried to form a photoresist layer 64 (FIG. C). Then, a photomask 65 which is patterned so as to divide each pixel into two is arranged on the photoresist layer 64, and light 66 is irradiated from above to perform exposure (FIG. D).

After exposure, it is developed with an alkaline developer. At this time, the exposed portion of the photoresist layer 64
Are etched, and the photoresist layer 64, which is covered with the photomask 65 and is not exposed, remains on the alignment layer 62 (FIG. E).

Next, the photomask 65 is removed, and a second rubbing is performed using a rotating cloth 63 in a direction different from the first rubbing by 180 degrees (FIG. F). And the alignment layer 6
The photoresist layer 64 remaining on 2 is peeled off (FIG. G). According to the method described above, the alignment layer 62 of each pixel is divided into two regions whose alignment directions are different by 180 degrees, for example.

In the above method, the alignment layer of each pixel has two alignment directions. However, for one pixel
It is also possible to have three or more orientation directions. In this case, steps such as patterning with a photomask, exposure, development, and rubbing are repeated depending on the number of orientation directions.

[0010]

When the alignment layer of each pixel is provided with a plurality of alignment directions using the photolithography technique, a mask pattern is formed each time the alignment direction is changed. Therefore, the number of steps is increased and the manufacturing cost is increased. Also, an alkaline solution is used in the developing step. For this reason, the alkaline solution damages the alignment layer and causes poor alignment, resulting in deterioration of display characteristics.

The present invention solves the above-mentioned drawbacks, and an object of the present invention is to provide a method for manufacturing a liquid crystal display device having a small number of steps and good alignment characteristics.

[0012]

A method of manufacturing a liquid crystal display device according to the present invention comprises a step of forming an alignment layer on a substrate including a plurality of pixel regions, and a step of performing a first alignment treatment on the alignment layer. A step of selectively printing a mask material on the alignment layer in a predetermined area in each pixel area to form a mask pattern covering the predetermined area, and a second step in the alignment layer having the mask pattern formed thereon. The method includes a step of performing an alignment treatment and a step of removing the mask pattern. In addition, a step of forming an alignment layer on a substrate including a plurality of pixel regions, a step of performing a first alignment treatment on the alignment layer, and a mask material on the alignment layer in almost half of each pixel region. The method includes selectively printing, forming a mask pattern covering the predetermined region, performing a second alignment treatment on the alignment layer on which the mask pattern is formed, and peeling the mask material. ing.

Further, a first step of forming an alignment layer on a substrate including a plurality of pixel regions, a second step of performing a first alignment treatment on the alignment layer, and each pixel region from the first region to the n-th region. A third step of dividing into n regions up to a region (where n is a natural number), selectively printing a mask material on the alignment layer in the first region, and forming a mask pattern covering the first region; A fourth step of performing a second alignment treatment on the alignment layer on which the mask pattern covering the first region is formed, and selecting a mask material on the alignment layer in one region of the n region which has not been masked yet. A fifth step of forming a mask pattern covering the one area that has not been masked yet, and a sixth step of performing an alignment treatment on the alignment layer on which the mask pattern is formed in the fifth step; Repeat the fifth step and the sixth step, ( It includes -2) times a seventh step of performing an alignment treatment of a eighth step of removing the mask pattern formed by this seventh step.

Further, a step of forming an alignment layer on a substrate including a plurality of pixel areas, a step of performing a first alignment treatment on the alignment layer, and a step of forming each pixel area in a first area, a second area, and a third area. Forming a mask pattern covering the first region by selectively printing a mask material on the alignment layer in the first region and dividing the region into a fourth region; and forming a mask pattern covering the first region. A step of performing a second alignment treatment on the alignment layer formed, a step of selectively printing a mask material on the alignment layer of the second region, and forming a mask pattern covering the second region; Performing a third alignment treatment on the alignment layer on which a mask pattern covering the first region and the second region is formed, and selectively printing a mask material on the alignment layer in the third region, Forming a mask pattern covering the three regions; A step of performing a fourth alignment treatment on the alignment layer on which a mask pattern covering the second area and the third area is formed, and a step of peeling off the mask pattern covering the first area, the second area and the third area. It has and.

Further, it is characterized in that the mask material is printed by an ink jet device. Further, the mask material is printed while the substrate on which the alignment layer is formed is heated.

Further, the printing of the mask material by the ink jet device is performed in a state where the substrate on which the alignment layer is formed is heated.

[0017]

According to the above structure, when each pixel region is divided into a plurality of regions and the alignment layer corresponding to one divided region is partially masked, a mask material is formed in the region where the mask is formed. Is directly printed. According to this method, unlike the case where the photolithography technique is used, there are no steps such as photoresist coating, development, and exposure, and the entire working process is simplified. Moreover, since there is no development step, it is not necessary to use an alkaline solution. Therefore, the alignment layer is not hydrolyzed by the alkaline solution to damage the alignment layer.

Further, when the mask material is printed by using the ink jet device, the mask pattern can be formed easily and surely. Further, when the mask material is printed in a state where the substrate is heated, the mask material is dried quickly, the mask material does not flow out to an unnecessary region, and a correct mask pattern can be formed.

[0019]

EXAMPLES Before describing the examples of the present invention, the cells of the liquid crystal display device produced by the present invention will be described with reference to FIG. FIG. 3 is a cross-sectional view of a cell of the liquid crystal display device.
31a is an upper substrate, and I.I. T. O.
A transparent electrode 32 of (Indium Tin Oxide) and an alignment layer 33 are formed. A plurality of pixel electrodes 3 are formed on the lower substrate 31b.
4 and TFT (Thin F corresponding to each pixel electrode 34)
An ilm Transistor) 35 and an alignment layer 33 are formed.
The upper substrate 31a and the lower substrate 31b are provided with respective alignment layers 33.
Are combined so that they are on the inner side, and a liquid crystal material is enclosed between them to form a liquid crystal layer 36. The alignment layer 33 of the lower substrate 31b is divided into two regions with the center of each pixel as a boundary 37, and the divided regions have different alignment directions. In addition, the boundary 37 of the lower substrate 31b
A storage capacitor 38 is formed so as to straddle. For example, when a region having a different alignment direction is formed for each pixel, the alignment of the liquid crystal molecules becomes unstable at the boundary 38 where the alignment direction changes, and a disclination line that shines white when viewed on the display screen is generated to deteriorate the image quality. . Therefore, the auxiliary capacitance 38
Is provided to shield the boundary portion 38 from light and prevent deterioration of image quality. The width of the auxiliary capacitor 38 is set to about 20 μm so that the displacement of the mask material formed on the alignment layer 33 of each pixel is within this width when forming regions having different alignment directions. . Here, one embodiment of the present invention will be described with reference to FIG. 5, taking as an example the case where each pixel on the lower substrate is provided with two alignment directions (dual domains).

The lower substrate 51 is prepared, and the lower substrate 51
Is washed with a neutral detergent and dried. After that, a polyimide alignment layer 52 is formed on the lower substrate 51 by a printing method to a thickness of about 85.
It is evenly formed to a thickness of 0 angstrom (Fig. A).
Then, the lower substrate 51 is passed under the roller 53 wound with cotton cloth, and the first rubbing is performed over the entire surface of the alignment layer 52 (FIG. B). The arrow Y indicates the rotation direction of the roller 53.

By the way, as shown in FIG.
Is divided into, for example, two regions, an upper half 41a and a lower half 41b. However, the first rubbing is for each pixel 41
In the u direction. At this time, the relative moving speed of the roller and the lower substrate is about 20 mm / sec, and the rotating speed of the roller is about 100 rpm.
After the first rubbing, the upper half area of each pixel,
For example, the mask material 54 is imprinted on the area 41a of FIG. 4A (FIG. C). At this time, the printing of the mask material is performed using the inkjet device 55.

Here, a pattern of printing a mask material using an ink jet device will be described with reference to FIG. A lower substrate 11 has a large number of pixel regions 12 formed on the lower substrate 11. Then, for example, the inkjet device 13 is moved in the arrangement direction of the pixel regions 12 (arrow Y), and each pixel region 12 is moved.
The mask material 14 is printed on the upper half. The dotted line 15
Is a boundary that divides the pixel region 12 into an upper half and a lower half.

In this case, as the mask material 14, for example, "OFPR-5000 manufactured by Tokyo Ohka Kogyo Co., Ltd." is used. In addition, one pixel 12 has, for example, a vertical length of about 30.
The length is 0 microns and the width is about 80 microns.
Therefore, the width of the mask material 14 to be printed is about 150 μm, and the upper half area of each pixel 12 is mask material 14
It is printed in stripes so that it is covered with. The mask material 14 has a viscosity coefficient of about 2.0 × 10 −2 g / cm · s.
I have to. In addition, when the lower substrate 11 is heated when the mask material 14 is printed, the printed mask material 14 dries faster, and the mask material 14 is prevented from flowing out to unnecessary portions on the alignment layer. be able to.

After printing the mask material in the above-described manner, second rubbing is performed in a v direction (see FIG. 4a) different from the first rubbing by 180 degrees (FIG. 4d). Also in this case, the roller 53 wound with cotton cloth that rotates in the direction of the arrow Y is used.
Then, the mask material is peeled off using an organic solvent such as acetone (Fig. E).

According to the above-mentioned method, the upper half 41a and the lower half 4 are formed on the alignment layers of the respective pixels as shown in FIG. 4 (a).
Two regions having an orientation direction different from that of 1b by 180 degrees are formed. In addition, the upper substrate is prepared separately from the lower substrate. In this case, the alignment treatment of the upper substrate is performed in one direction, for example, rubbing in the t direction as shown in FIG.

After rubbing the upper substrate and the lower substrate, the alignment layers are placed inside so as to be assembled via a spacer and sealed with a sealing material. Then, the liquid crystal is sealed to form a liquid crystal layer, and a cell of the liquid crystal display device is configured.

An ink jet device used for printing a mask material will be described with reference to FIG. 2 by taking a Kyser type as an example. Reference numeral 21 denotes a pressure chamber for accumulating ink therein. A nozzle 22 is provided at one end of the pressure chamber 21, and an ink supply port 23 is provided at the other end. A piezo element 24 is attached to the outside of the pressure chamber 21.
With such a structure, when a voltage is applied to the piezo element 24, the piezo element 24 deforms and the wall of the pressure chamber 21 bends (FIG. B). As a result, pressure is applied to the ink inside the pressure chamber 21, the ink is pushed out from the nozzle 22 and the ink supply port 23, and an ink column 25 is generated in the nozzle 22. After that, the piezo element 24 tries to return to the original state. At this time, the tip portion of the ink column 25 becomes a droplet 26 and is separated in the arrow Y direction so as to fly. After that, ink flows in from the ink supply port 23 and returns to the state of FIG. Such an operation is repeated, and the image is printed with the ink flying in a droplet shape.

When the mask material is printed with the lower substrate heated, for example, as shown in FIG. 1B, the lower substrate 11 is placed on the hot plate 16 and the ink jet apparatus is placed in this state. The mask material is printed by 17.

In the above-mentioned embodiment, when the mask material is printed by using the ink jet device, the mask material is printed in stripes on the same side of all pixels, for example, the upper half. However, between adjacent pixels, one pixel masks the upper half area, the other pixel masks the lower half area, and the second rubbing is performed, and the same orientation direction alternates between the adjacent pixels. You may make it go up and down. Further, the rubbing of the upper substrate may be performed in a plurality of directions instead of one direction.

When the mask material is printed by the ink jet device, an ink jet device having a narrow width on which the mask material is printed is used, and the ink jet device is reciprocated several times to obtain half of each pixel. The width of may be printed. Next, in the second embodiment of the present invention, a case where each pixel is divided into four and orientation processing in four directions is performed will be described with reference to FIG.

Also in this case, similarly to the first embodiment, the upper substrate and the lower substrate are prepared, washed with a neutral detergent and dried. Then, a polyimide alignment layer is uniformly formed on the surface of the lower substrate by a printing method to a thickness of about 850 Å. Then, the first rubbing is performed on the entire surface of the alignment layer in the w direction, for example. Next, each pixel is divided into four 41c to 41f, and a mask material is printed on one divided area, for example, 41c by using an inkjet device (not shown). Then, second rubbing is performed in the x direction that is different from the first rubbing by 180 degrees. In addition, another area 41
A mask material is printed on d using an inkjet device, and third rubbing is performed in the y direction. After that, the mask material is printed on the other region 41e by using the inkjet device, and the fourth rubbing is performed in the z direction. Finally, the mask material is peeled off using an organic solvent such as acetone. By doing so, the alignment layer of each pixel is aligned in the four directions w to z.

Further, with respect to the upper substrate, in the same manner as the lower substrate, for example, as shown in FIG.
Rubbing to have n, o, and p.

After rubbing the lower substrate and the upper substrate by the above-mentioned method, the upper substrate and the lower substrate are combined with each other with the alignment layers facing inward through spacers, as in the first embodiment, and Seal with sealing material. After that, a liquid crystal is enclosed to form a liquid crystal layer to form a cell of a liquid crystal display device.

The number of alignment directions formed in one pixel is not limited to 2 or 4 as described above. In general, each pixel can be divided into n parts to have n orientation directions. In this case, printing or rubbing of the mask material is repeated according to the number of orientation directions. For example, the number of times of rubbing is n, and the number of times of printing the mask material is (n-1).

In the above embodiment, an ink jet device is used as a means for printing the mask material. But,
Not limited to the inkjet device, any device that can partially print can be used. Also, as a material for the mask material,
For example, a polyvinyl alcohol aqueous solution can be used. In this case, water can be used as a stripping solution for the mask, which is advantageous in terms of cost, equipment, and environment.

Further, in the above embodiment, the TFT is used as the driving means of the liquid crystal display device. But MI
It is also possible to use drive using M (Metal Insulator Metal) or multiplex drive using a simple matrix electrode structure having no switching element. It can also be applied to a GH (Guest Host) mode liquid crystal display device to which a dye is added.

[0037]

According to the present invention, it is possible to realize a method of manufacturing a liquid crystal display device in which the number of steps is small and the alignment layer is less damaged.

[Brief description of drawings]

FIG. 1 is a diagram showing a printed state of a mask material according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view briefly showing the structure of a Kyser type inkjet device.

FIG. 3 is a cross-sectional view of a liquid crystal cell manufactured according to an embodiment of the present invention.

FIG. 4 is a diagram showing an alignment direction of one pixel in one embodiment of the present invention.

FIG. 5 is a process chart illustrating an example of the present invention.

FIG. 6 is a process diagram illustrating a conventional example.

[Explanation of symbols]

 11 ... Lower substrate 12 ... Pixel region 13 ... Inkjet device 14 ... Mask material 15 ... Border

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hitoshi Hato 8 Shinsita-cho, Isogo-ku, Yokohama-shi, Kanagawa Stock company Toshiba Yokohama office

Claims (7)

[Claims] 1. A step of forming an alignment layer on a substrate including a plurality of pixel regions, a step of performing a first alignment treatment on the alignment layer, and a mask on a predetermined region of the alignment layer in each pixel region. A step of selectively printing a material to form a mask pattern covering the predetermined region; a step of performing a second alignment treatment on the alignment layer on which the mask pattern is formed; and a step of peeling the mask pattern And a method for manufacturing a liquid crystal display device. 2. A step of forming an alignment layer on a substrate including a plurality of pixel regions, a step of performing a first alignment treatment on the alignment layer, and a step of forming an alignment layer on the alignment layer in a region approximately half of each pixel region. Selectively printing a mask material, forming a mask pattern that covers the predetermined region, performing a second alignment treatment on the alignment layer on which the mask pattern is formed, and peeling the mask pattern A method for manufacturing a liquid crystal display device, comprising: 3. A first step of forming an alignment layer on a substrate including a plurality of pixel regions, a second step of performing a first alignment treatment on the alignment layer, and each pixel region from the first region to the n-th region. A third step of dividing into n regions up to a region (where n is a natural number), selectively printing a mask material on the alignment layer in the first region, and forming a mask pattern covering the first region; A fourth step of performing a second alignment treatment on the alignment layer on which the mask pattern covering the first region is formed, and selecting a mask material on the alignment layer in one region of the n region which has not been masked yet. A fifth step of forming a mask pattern covering the one area that has not been masked yet, and a sixth step of performing an alignment treatment on the alignment layer on which the mask pattern is formed in the fifth step; Repeating the fifth step and the sixth step, (n-2 ) Seventh step of performing orientation processing,
A method of manufacturing a liquid crystal display device, comprising: an eighth step of removing the mask pattern formed up to the seventh step. 4. A step of forming an alignment layer on a substrate including a plurality of pixel areas, a step of performing a first alignment treatment on the alignment layer, and a step of forming each pixel area in a first area, a second area, and a third area. Forming a mask pattern covering the first region by selectively printing a mask material on the alignment layer in the first region and dividing the region into a fourth region; and forming a mask pattern covering the first region. A step of performing a second alignment treatment on the alignment layer formed, a step of selectively printing a mask material on the alignment layer of the second region, and forming a mask pattern covering the second region; A step of performing a third alignment treatment on the alignment layer in which a mask pattern covering the first region and the second region is formed,
A step of selectively printing a mask material on the alignment layer in the third region to form a mask pattern covering the third region, and a mask pattern covering the first region, the second region and the third region are formed. A method of manufacturing a liquid crystal display device, comprising: performing a fourth alignment treatment on the formed alignment layer; and removing a mask pattern covering the first region, the second region and the third region. 5. The method of manufacturing a liquid crystal display device according to claim 1, wherein the mask material is printed by an inkjet device. 6. The method for manufacturing a liquid crystal display device according to claim 1, wherein the printing of the mask material is performed in a state where the substrate on which the alignment layer is formed is heated. 7. The method of manufacturing a liquid crystal display device according to claim 5, wherein the printing of the mask material by the inkjet device is performed in a state where the substrate on which the alignment layer is formed is heated.