JP2004252242A - Liquid crystal display device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device provided with strength and impact resistance to external pressure and capable of obtaining satisfactory display characteristics and to provide its manufacturing method. <P>SOLUTION: The liquid crystal display has substrates 2 and 4 at least one of which is transparent, a liquid crystal 6 sealed between the substrates 2 and 4 and columnar spacers 20 formed by using a rubber based photoresist, adhering to both substrates 2 and 4 and maintaining a cell gap between the substrates 2 and 4. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid crystal display device and a method for manufacturing the same. More specifically, the present invention relates to a liquid crystal display device in which a medium having an optical switch function generally known as a liquid crystal is sandwiched between a pair of substrates at least one of which is transparent, Also, the present invention relates to a liquid crystal display device in which uniformity such as contrast and response speed is improved by maintaining a uniform and constant cell gap between substrates in an effective display region to obtain good display quality, and a method of manufacturing the same.
[0002]
[Prior art]
A liquid crystal display device in which a liquid crystal which is a medium having an optical switching function is filled between a pair of substrates, at least one of which is transparent, is generally thin, lightweight, and consumes low power. For this reason, it is widely used as a display device such as a calculator, a home appliance or an OA device, and a spatial light modulator (Spacial Light Modulator).
[0003]
In the liquid crystal display device, it is essential that the cell gap between the substrates is uniform and constant in the display area in order to perform good display. In order to maintain a uniform and constant cell gap, spacers are arranged between the substrates. The spacers are roughly classified into spherical spacers in the form of particles (beads) and columnar spacers in the form of pillars (pillars). Conventionally, various techniques for arranging and fixing these spacers have been developed.
[0004]
As a general method, there is a method of dispersing spherical spacers on a substrate to uniformly control a cell gap. However, this method has a problem that it is difficult to control the arrangement of the spherical spacers. In addition, since the spherical spacers are scattered in the pixel area which is indispensable for display, light is scattered by the spherical spacers, which causes a decrease in contrast or alignment defects of liquid crystal molecules in the pixel area. There has been a problem that the quality is reduced.
[0005]
In order to solve the above problem, a technique has been proposed in which, instead of dispersing spherical spacers, columnar spacers are selectively formed in a region other than a pixel region by a photolithography method. According to this technique, since there is no spacer in the pixel region, light leakage due to alignment defects or the like of liquid crystal molecules is suppressed. Therefore, the contrast of the liquid crystal display device is improved, and a decrease in display quality can be prevented. However, the columnar spacer is usually adhered to one substrate, but not adhered to the other substrate. For this reason, when an external pressure (external pressure) such as being pressed by a fingertip is applied to a part of the substrate surface, the area between the substrates to which the external pressure is applied becomes narrow, and the other area becomes wide. . With the change in the substrate interval, the interval between the electrodes formed on both substrates changes. Therefore, problems such as the occurrence of interference fringes, variations in color tone, variations in driving voltage characteristics, and variations in response speed of liquid crystal have occurred. In an extreme case, the substrates are brought into contact with each other due to the external pressure, and the alignment film is damaged, whereby the alignment of the liquid crystal is disturbed and the display quality is deteriorated.
[0006]
Therefore, studies have been made to improve the display quality by providing the columnar spacers with adhesiveness to both of the substrates and suppressing variations in the response speed of the liquid crystal. However, it has been difficult to achieve both precise control of the cell gap and high adhesiveness. For example, there is a method in which a spherical spacer that is not deformed by pressure or heat is contained in a columnar spacer, the strength of the columnar spacer is increased, the cell gap is precisely controlled, and high adhesiveness is realized (for example, Patent Document 1). . However, in this method, since the spherical spacers are dispersed in the resin for forming the columnar spacers, the following problems occur.
(1) Since there is a columnar spacer that does not contain a spherical spacer, the uniformity of the cell gap is inferior.
(2) If the content of the spherical spacer is increased to avoid the problem of (1), the spherical spacer acts as a filler and exerts an adverse effect, making it difficult to uniformly spin coat the columnar spacer forming material on the substrate. . For this reason, the applied thickness of the columnar spacer forming material becomes uneven, and as a result, the height of the columnar spacer becomes uneven.
(3) Spherical spacers having a uniform particle size are expensive. Moreover, since parts other than the columnar spacers are removed by patterning, most of the spherical spacers are discarded. For this reason, the manufacturing cost of the liquid crystal display device increases.
[0007]
As another method, Japanese Patent Application (Japanese Patent Application No. 2002-138627) filed by the present applicant proposes a technique for imparting adhesiveness to a spacer so that a cell gap does not vary with an external pressure.
[0008]
[Patent Document 1]
JP 2000-155321 A
[0009]
[Problems to be solved by the invention]
However, in the above technique, the elasticity is low because the spacers are all formed of a relatively hard resin. For this reason, when a larger external pressure is applied to the substrate surface, the adhesion portion of the spacer is disengaged, the cell gap fluctuates, and the display is disturbed. Further, when an impact is applied to the liquid crystal display device due to a drop or the like, a problem arises in that a bonding portion of the spacer is removed and a cell gap is easily changed.
[0010]
As described above, conventional techniques for arranging and fixing spacers have not been sufficient to realize a liquid crystal display device that is strong against external pressure, has high impact resistance, and has good display characteristics.
Further, when the conventional spacers are used, it is difficult to apply the alignment film material solution in a state where the spacers are uniformly and densely arranged on the substrate. Further, the spacer may be peeled off during the rubbing treatment of the alignment film. For this reason, it was difficult to fix the spacer on the substrate while maintaining the display quality of the liquid crystal display device.
[0011]
SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device having strength against external pressure and impact resistance and capable of obtaining good display characteristics, and a method for manufacturing the same.
[0012]
[Means for Solving the Problems]
The object is to form a pair of substrates at least one of which is transparent, a liquid crystal sealed between the pair of substrates, and a columnar spacer formed of a rubber-based photoresist and maintaining a cell gap between the pair of substrates. This is achieved by a liquid crystal display device characterized by having.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
A liquid crystal display device and a method of manufacturing the same according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of the liquid crystal display device according to the present embodiment. As shown in FIG. 1, the liquid crystal display device includes a TFT substrate 2 on which thin film transistors (TFTs), pixel electrodes, gate bus lines, drain bus lines, and the like are formed, a color filter, a common electrode, and the like. And a liquid crystal display panel in which liquid crystal (not shown in FIG. 1) is sealed therebetween.
[0014]
The TFT substrate 2 includes a gate bus line driving circuit 80 on which a driver IC for driving a plurality of gate bus lines is mounted and a drain bus line driving circuit 82 on which a driver IC for driving a plurality of drain bus lines is mounted. Is provided. Both drive circuits 80 and 82 output a scanning signal and a data signal to a predetermined gate bus line or a drain bus line based on a predetermined signal output from the control circuit 84. A polarizing plate 87 is attached to a surface of the TFT substrate 2 opposite to the element forming surface, and a backlight unit 88 is disposed on a surface of the polarizing plate 87 opposite to the TFT substrate 2. On the other hand, a polarizing plate 86 is attached to a surface of the opposite substrate 4 opposite to the surface on which the common electrode is formed.
[0015]
FIG. 2 shows a schematic sectional configuration of the liquid crystal display device according to the present embodiment. As shown in FIG. 2, the TFT substrate 2 and the opposing substrate 4 are bonded together via, for example, a thermosetting sealing material 12 applied to the outer peripheral portion. At least one of the substrates 2 and 4 is formed using a transparent substrate such as glass. Although not shown, a pixel electrode is formed for each pixel on the TFT substrate 2, and a common electrode is formed on almost the entire surface of the counter substrate 4. At least an electrode formed on a transparent substrate among the pixel electrode and the common electrode is formed of a transparent conductive film. On the opposing surfaces of the TFT substrate 2 and the opposing substrate 4, alignment films for regulating the alignment of the liquid crystal 6 are formed. The alignment film is formed of a resin such as polyimide, and has been subjected to a predetermined rubbing treatment.
[0016]
The cell gap between the two substrates 2 and 4 is maintained by a columnar spacer 20 formed on one of the substrates by using a photolithography method. The columnar spacer 20 is formed using, for example, a thermosetting rubber-based photoresist and has relatively high elasticity. The columnar spacer 20 is cured by being heated to a predetermined temperature after the substrates 2 and 4 are overlapped. The columnar spacers 20 have, for example, a cylindrical shape with a diameter of 10 μm, and are arranged in a matrix at intervals of 100 μm. Both bottom surfaces of the columnar spacer 20 are bonded surfaces bonded to the substrates 2 and 4, respectively. The columnar spacer 20 is adhered to both the substrates 2 and 4 to firmly connect the substrates 2 and 4, and also keeps the cell gap between the substrates 2 and 4 uniform and constant.
[0017]
Since the rubber-based photoresist can be patterned by a photolithography method, it is easy to form the columnar spacer 20 at a desired position. For this reason, the columnar spacer 20 can be arranged only in a region other than the pixel region of the liquid crystal display device and effective in maintaining a constant cell gap between the substrates 2 and 4. Further, the cell gap can be easily controlled by adjusting the thickness of the rubber-based photoresist film applied and formed on the entire surface of the substrate prior to patterning.
[0018]
The thermosetting sealing material 12 is applied to the outer peripheral portion of one of the substrates 2 and 4, and is heated to a predetermined temperature and cured after the substrates 2 and 4 are overlapped. The cured sealing material 12 has a sealing function of preventing the liquid crystal 6 from leaking. A resin material is usually used for the sealing material 12. If the curing temperature of the rubber-based photoresist forming the columnar spacer 20 is equal to or lower than the curing temperature of the sealing material 12, the columnar spacer 20 is cured first to set a predetermined cell gap, and the cell gap is maintained. The outer peripheral portion between the substrates 2 and 4 can be sealed. Therefore, if the curing temperature of the rubber-based photoresist is equal to or lower than the curing temperature of the sealing material 12, the bonding between the substrates 2, 4 by forming the columnar spacers 20 and the outer peripheral portions of the substrates 2, 4 due to the curing of the sealing material 12 Can be performed in the same step.
[0019]
In the heating step after the substrates 2 and 4 are overlapped as described above, it is important to heat the alignment film at a temperature lower than the temperature at which the rubbing effect of the alignment film is impaired. In general, the rubbing effect of the alignment film is impaired at a temperature higher than 150 ° C., so that heating to a temperature higher than 150 ° C. should be avoided. For this reason, the curing temperature of the rubber photoresist and the sealing material 12 is desirably 150 ° C. or lower. Generally, after the liquid crystal 6 is sealed between the substrates 2 and 4, the annealing temperature for reorienting the liquid crystal 6 is about 110 ° C. For this reason, the curing temperature of the rubber-based photoresist and the sealing material 12 is desirably 110 ° C. or higher so that the columnar spacer 20 and the sealing material 12 are not cured during the annealing process.
[0020]
In the present embodiment, a thermosetting resin is used as the sealant 12, but a photocurable resin can also be used. If a photocurable resin is used as the sealant 12, the space between the substrates 2 and 4 can be sealed at a lower temperature.
[0021]
The TFT substrate 2 and the opposing substrate 4 of the liquid crystal display device according to the present embodiment are aligned at predetermined positions facing each other in a state where the columnar spacers 20 are uncured (or semi-cured). Then, the columnar spacer 20 is adhered to both the substrates 2 and 4 by heating and curing the uncured columnar spacer 20, and the substrates 2 and 4 are joined. By pressing the substrates 2 and 4 after the columnar spacer 20 is cured to some extent, deformation of the columnar spacer 20 is suppressed, and a desired cell gap is obtained.
[0022]
The liquid crystal used in the liquid crystal display device according to the present embodiment is not particularly limited. For example, twisted nematic (TN) type liquid crystal, super twisted nematic (STN) type liquid crystal, vertically aligned (VA) type liquid crystal, nematic cholesteric phase transition type liquid crystal, polymer dispersed type liquid crystal, ferroelectric liquid crystal, antiferroelectricity Known liquid crystals such as a liquid crystal, a twist grain boundary liquid crystal, and a smectic A-phase liquid crystal exhibiting an electroclinical effect can be used.
[0023]
In this embodiment, the columnar spacer 20 has relatively high elasticity because it is formed of a rubber-based photoresist. The columnar spacer 20 is adhered to both the substrates 2 and 4. For this reason, even if a large external pressure is applied to a part of the substrate surface and the cell gap fluctuates, the columnar spacer 20 expands and contracts in accordance with the cell gap fluctuation, and the bonding portion of the columnar spacer 20 to the substrates 2 and 4 is reduced. It does not come off. Further, when the cell gap fluctuates and the columnar spacer 20 expands and contracts, a force is generated in the columnar spacer 20 in a direction for maintaining a predetermined cell gap by elasticity. Therefore, even if an external pressure is applied to a part of the substrate surface and the cell gap temporarily fluctuates, removing the external pressure recovers the cell gap and the cell gap does not fluctuate continuously. Therefore, a liquid crystal display device that is strong against external pressure and has good display characteristics can be obtained. Further, even if an impact is applied to the liquid crystal display device, the adhesion of the adhesion portion does not occur and the cell gap does not continuously change due to the elasticity of the columnar spacer 20. Therefore, a liquid crystal display device having high impact resistance can be obtained.
[0024]
Further, in the present embodiment, since the columnar spacers 20 are used instead of the spherical spacers scattered on the substrate, there is no problem that the spacers peel off during the rubbing treatment of the alignment film.
[0025]
Next, a method for manufacturing the liquid crystal display device according to the present embodiment will be described with reference to FIG. FIG. 3 is a process sectional view illustrating the method for manufacturing the liquid crystal display according to the present embodiment. First, an alignment film is formed by applying polyimide or the like to each surface of the TFT substrate 2 and the counter substrate 4 that have been manufactured through predetermined processes. Next, as shown in FIG. 3A, for example, a negative rubber-based photoresist is applied to the entire surface of the counter substrate 4 by using, for example, a spin coating method, and a rubber-based photoresist film 30 having a thickness of 2 μm is formed. Form. Next, the rubber-based photoresist film 30 is pre-baked. Next, exposure is performed by an ultraviolet exposure apparatus using a negative type photomask in which a region for forming the columnar spacer 20 is opened. In this exposure step, the rubber-based photoresist film 31 in the area where the columnar spacer 20 is formed is exposed at a predetermined exposure amount.
[0026]
Next, the exposed rubber-based photoresist films 30 and 31 are developed to form uncured columnar spacers 21 as shown in FIG. The columnar spacers 21 have, for example, a cylindrical shape with a diameter of 10 μm, and are arranged in a matrix at intervals of 100 μm. Subsequently, the columnar spacer 21 is washed with pure water and dried. Subsequently, a rubbing process is performed on the alignment films on the substrates 2 and 4.
[0027]
Next, as shown in FIG. 3C, a thermosetting sealing material 12 is applied to the outer peripheral portion of the counter substrate 4, for example, except for a portion serving as a liquid crystal injection port. Next, the two substrates 2 and 4 are superposed to produce a superposed substrate. Next, the superposed substrate is loaded into a heat treatment apparatus, and is heated under pressure at a curing temperature of the uncured columnar spacer 21 and the sealing material 12 (for example, 110 ° C. to 150 ° C.). Here, by deforming the columnar spacer 21 to some extent by heating and then pressing the superposed substrate, deformation of the uncured columnar spacer 21 is suppressed, and a desired cell gap is obtained. The columnar spacer 21 is cured in a state where pressure is applied from both substrates 2 and 4, and becomes the columnar spacer 20 adhered to both substrates 2 and 4. At the same time, the sealing material 12 is cured, and the outer peripheral portions of the substrates 2 and 4 are sealed. At this time, the columnar spacers 21 are hardened almost simultaneously with the sealing material 12 or earlier than the sealing material 12. The two substrates 2 and 4 are firmly connected by the columnar spacer 20 and the sealing material 12. Thereafter, the liquid crystal 6 is injected between the two substrates 2 and 4 from the liquid crystal injection port, and the liquid crystal injection port is sealed with a sealing material. Through the above steps, the liquid crystal display device shown in FIG. 2 is completed.
[0028]
As a method of injecting the liquid crystal between the substrates 2 and 4, a vacuum injection method of filling and enclosing the liquid crystal using a vacuum between the substrates 2 and 4, which are previously opposed and bonded as described above, and a method of injecting the opposing substrate 4 ( Alternatively, a typical example is a drop injection method in which liquid crystal is dropped on the TFT substrate 2), and the TFT substrate 2 (or the counter substrate 4) is stacked and bonded. This embodiment is applicable to any liquid crystal injection method. In the case of the drop-injection method, for example, an uncured columnar spacer 20 is formed on the opposing substrate 4, a sealing material 12 is applied and formed on the outer periphery of the opposing substrate 4 or the TFT substrate 2, and after the liquid crystal 6 is dropped, the two substrates are dropped. 2 and 4 are superposed to produce a superposed substrate filled with liquid crystal 6. Thereafter, the superposed substrate is heated under pressure. Thereby, the sealing material 12 is cured and the uncured columnar spacers 20 are cured, and the columnar spacers 20 adhered to both the substrates 2 and 4 are obtained.
[0029]
Further, the present embodiment is applicable to other liquid crystal injection methods. For example, the liquid crystal 6 is adhered to the counter substrate 4 (or the TFT substrate 2) on which the sealing material 12 is not formed at all in the outer peripheral portion. Next, the substrates 2 and 4 are overlapped with each other, and the liquid crystal 6 is filled between the substrates 2 and 4 to form an overlapped substrate. Thereafter, the outer peripheral portion of the superposed substrate is sealed with a sealing material. Alternatively, the sealing material 12 is formed only in a limited part of the limited area, and the sealing material 12 is formed on the counter substrate 4 (or the TFT substrate 2) on which the sealing material 12 is not substantially formed. The liquid crystal 6 is adhered to the region where there is no liquid crystal. Next, the substrates 2 and 4 are overlapped with each other, and the liquid crystal 6 is filled between the substrates 2 and 4 to form an overlapped substrate. Thereafter, a region of the outer peripheral portion of the superposed substrate where the sealant 12 is not formed is sealed with the sealant. If these liquid crystal injection methods are used, the liquid crystal 6 can be efficiently injected between the substrates 2 and 4. Therefore, the throughput in the manufacturing process of the liquid crystal display device can be improved, the manufacturing cost can be reduced, and the manufacturing yield can be improved.
[0030]
When the above-described liquid crystal injection method is used, the liquid crystal 6 may be filled between the substrates 2 and 4 using, for example, a pressure difference or a temperature difference before and after the liquid crystal 6 is attached to the counter substrate 4 or both. . Thereby, the liquid crystal 6 can be filled between the substrates 2 and 4 in a shorter time. Further, for example, when attaching the liquid crystal 6 to the counter substrate 4, the liquid crystal 6 may be dropped using a dispenser. The use of the dispenser makes it possible to apply the liquid crystal 6 quantitatively and easily.
[0031]
In the present embodiment, the rubber-based photoresist that is the material for forming the columnar spacer 20 does not contain a spherical spacer. For this reason, uniform spin coating of the rubber-based photoresist on the substrate becomes possible, and the columnar spacer 20 having a uniform height can be formed. Therefore, a uniform cell gap can be obtained over the entire display area. In the present embodiment, the columnar spacer 20 (21) is formed by patterning the rubber-based photoresist film 30 formed by applying a rubber-based photoresist. Therefore, the columnar spacer 20 can be formed at a desired position by an easy process. Furthermore, in the present embodiment, since the columnar spacers 20 (21) are formed on the alignment film, there is no problem with the application of the alignment film material solution in a state where the spacers are arranged on the substrate.
[0032]
In the present embodiment, a negative rubber photoresist is used as a material for forming the columnar spacer 20, but a positive rubber photoresist can also be used. In general, higher adhesiveness can be obtained by using a positive type rubber-based photoresist. However, if a negative type rubber-based photoresist is used, the hardness of the uncured columnar spacer 21 can be controlled by the exposure amount.
[0033]
Hereinafter, the liquid crystal display device according to the present embodiment and the method of manufacturing the same will be described using specific examples and comparative examples.
(Example 1)
First, a liquid crystal display device according to Example 1 of the present embodiment and a method for manufacturing the same will be described. Based on the method for manufacturing the liquid crystal display device according to the present embodiment described above, the liquid crystal display device according to the present example was manufactured as follows. On a pair of glass substrates of 200 mm × 100 mm × 1.1 mm each having a transparent electrode made of ITO (Indium Tin Oxide) formed on one surface, a 3 wt% concentration polyimide solution is applied by a spin coater at a rotation speed of 2000 rpm. Next, the glass substrate is baked at 200 ° C. for 30 minutes to form an alignment film.
[0034]
For example, a negative type rubber-based photoresist (for example, OMR85, manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied on the alignment film of one glass substrate (opposing substrate 4) by a spin coating method, and a 2 μm-thick rubber-based photoresist film is applied. Form 30. Next, the rubber-based photoresist film 30 is pre-baked at 80 ° C. for 15 minutes using a hot plate. Next, the integrated irradiation amount was 100 mJ / cm by an ultraviolet exposure device. ² Exposes the rubber-based photoresist film 30. Next, the exposed rubber-based photoresist film 30 is developed to form an uncured columnar spacer 21. The columnar spacers 21 have a cylindrical shape with a diameter of 10 μm, and are arranged in a matrix at intervals of 100 μm. Next, the columnar spacer 21 is washed with pure water and dried. Subsequently, a rubbing process is performed on the alignment films on the substrates 2 and 4.
[0035]
Next, an epoxy resin that cures at 150 ° C. for one hour is adhered to the outer peripheral portion of the opposite substrate 4 except for the portion serving as the liquid crystal injection port by a printing method, thereby forming the sealant 12. Next, the two substrates 2 and 4 are overlapped so that the transparent electrodes face each other, thereby producing an overlapped substrate. Next, the overlapped substrate is placed in a vacuum bag and heated at 150 ° C. for 1 hour to cure the sealing material 12 and to cure the uncured columnar spacer 21, thereby bonding the columnar spacer adhered to both the substrates 2 and 4. 20 are formed. Thereby, a bonded substrate is manufactured. Next, a ferroelectric liquid crystal is injected from the liquid crystal injection port using a vacuum injection method, and the liquid crystal injection port is sealed. Through the above steps, a liquid crystal display device was obtained.
[0036]
This liquid crystal display device was placed under crossed Nicols, and the center of the display was pressed with a load of 300 g using a pen tip having a tip diameter of 0.8 mm. While the display color changed around the pen tip while the load was applied, the display returned to good when the load was removed. This indicates that the liquid crystal display device has stress resistance against an external pressure that reduces the thickness of the liquid crystal layer. In addition, a center portion of the liquid crystal display device was supported, and a load of 500 g was applied to both ends. Although a change in display color was observed on the display screen while the load was being applied, the display returned to good display over the entire display screen when the load was removed. Further, when a predetermined impact was applied to the liquid crystal display device, no change in display quality was observed. This indicated that the liquid crystal display device had impact resistance.
[0037]
(Comparative Example 1)
Here, in order to compare with the liquid crystal display device according to the first embodiment, the size and shape of the glass substrate, the conditions of the alignment film, the liquid crystal material, and the like are the same as those in the first embodiment, and the negative type rubber for forming the columnar spacer 20 is used. The exposure time of the system photoresist film 31 is changed to five times the exposure time of the first embodiment. Thereby, the strength of the uncured columnar spacer 21 when the substrates 2 and 4 are overlapped increases.
[0038]
As in the first embodiment, a rubber-based photoresist film 30 having a thickness of 2 μm is formed on the alignment film of the counter substrate 4. Next, the rubber-based photoresist film 30 is pre-baked at 80 ° C. for 15 minutes using a hot plate. Next, the integrated irradiation amount was 500 mJ / cm by an ultraviolet exposure device. ² Exposes the rubber-based photoresist film 30. Next, the exposed rubber-based photoresist film 30 is developed to form an uncured columnar spacer 21. Thereafter, a liquid crystal display device was manufactured in the same steps as in Example 1.
[0039]
This liquid crystal display device was placed under crossed Nicols, and the center of the display was pressed with a load of 300 g using a pen tip having a tip diameter of 0.8 mm. While the load was applied, a change in display color was observed around the pen tip. Even when the load was removed, the display did not return to a good level. This indicates that this liquid crystal display device is inferior in stress resistance to external pressure in the direction of reducing the thickness of the liquid crystal layer. In addition, a center portion of the liquid crystal display device was supported, and a load of 500 g was applied to both ends. While the load was applied, the display color changed over the entire screen. Even when the load was removed, the display did not return to a good level. This is because the columnar spacer 20, which has already been cured before the substrates 2 and 4 are superposed, is not sufficiently adhered to the TFT substrate 2 side. That's because Further, it was found that this liquid crystal display device was inferior to the liquid crystal display device of Example 1 in impact resistance.
[0040]
As described above, the liquid crystal display device of the present modification is inferior in strength against external pressure, impact resistance, and display characteristics to those of the liquid crystal display device of the first embodiment. This is because the columnar spacer 21 and the TFT substrate 2 are not adhered to each other even if the substrates 2 and 4 are heated after the substrates 2 and 4 are overlapped, because the columnar spacer 21 is hardened due to the long exposure time and the strength is increased. It is thought that it was enough.
[0041]
(Comparative Example 2)
As in Example 1, except that a negative resist that cures at 190 ° C. for 1 hour was used as a material for forming the columnar spacer 20 and the substrates 2 and 4 were superposed and heated and cured at 190 ° C. for 1 hour. A liquid crystal display device was manufactured. As a result, the alignment film was damaged by heat, and the alignment control force for the liquid crystal was reduced, and the display quality of the liquid crystal display device was reduced.
[0042]
(Comparative Example 3)
A liquid crystal display was formed in the same manner as in Example 1, except that a negative resist that cured at 150 ° C. for 1 hour was used as a material for forming the columnar spacer 20 and an epoxy resin that cured at 140 ° C. for 1 hour was used as the sealing material 12. The device was made. As a result, the columnar spacer 20 was hardened after the sealing material 12 on the outer peripheral portion of the liquid crystal display panel was hardened, so that the central portion of the display area swelled, the cell gap became nonuniform, and the display quality of the liquid crystal display device deteriorated.
[0043]
(Comparative Example 4)
A negative resist that cures at 100 ° C. for one hour is used as a material for forming the columnar spacer 20, and an epoxy resin that cures at 100 ° C. for one hour is used as the sealant 12. Further, the columnar spacer 20 and the sealing material 12 are cured at 100 ° C. by using a drop injection method in which the liquid crystal is dropped on one of the substrates while heating, and then the substrates are overlapped. Except for the above, a liquid crystal display device was manufactured in the same manner as in Example 1. As a result, the curing temperature of the negative resist and the sealing material 12 is low, so that when the liquid crystal is filled in a heated state (100 ° C.), the curing of the columnar spacer 20 starts. For this reason, the adhesion between the columnar spacer 20 and the TFT substrate 2 could not be obtained, and the display quality of the liquid crystal display device deteriorated.
[0044]
(Comparative Example 5)
A negative resist that cures at 160 ° C. for 1 hour is used as a material for forming the columnar spacer 20, and an epoxy resin that cures at 160 ° C. for 1 hour is used as the sealing material 12, and the columnar spacer 20 and the sealing material 12 are cured at 160 ° C. A liquid crystal display device was manufactured in the same manner as in Example 1 except that the operation was performed. As a result, the alignment film was damaged by heat, and the alignment control force for the liquid crystal was reduced, and the display quality of the liquid crystal display device was reduced.
[0045]
(Example 2)
Next, a liquid crystal display device according to a second embodiment of the present embodiment and a method for manufacturing the same will be described. A liquid crystal display device was manufactured in the same manner as in Example 1, except that the liquid crystal was injected by the drop injection method. First, a sealing material 12 is applied to the outer peripheral portion of one glass substrate (opposite substrate 4). Next, an uncured columnar spacer 21 is formed on the counter substrate 4, for example. Next, for example, liquid crystal is dropped on the counter substrate 4 using a dispenser. Next, the substrates 2 and 4 are overlapped under vacuum so that the transparent electrodes face each other, and heated at 150 ° C. for 1 hour to cure the sealing material 12 and the columnar spacer 21. Through the above steps, a liquid crystal display device is completed. This liquid crystal display device exhibited stress resistance to external pressure, impact resistance, and good display characteristics, as in Example 1.
[0046]
The present invention is not limited to the above embodiment, and various modifications are possible.
For example, in the above embodiment, the columnar spacers 20 are formed on the counter substrate 4, but the present invention is not limited to this, and the columnar spacers 20 may be formed on the TFT substrate 2.
[0047]
In the above embodiment, a transmissive liquid crystal display device is described as an example. However, the present invention is not limited to this, and can be applied to other liquid crystal display devices such as a reflective liquid crystal display device and a transflective liquid crystal display device.
[0048]
The liquid crystal display device and the method of manufacturing the same according to the above-described embodiments are summarized as follows.
(Appendix 1)
A pair of substrates at least one of which is transparent,
Liquid crystal sealed between the pair of substrates,
A columnar spacer formed of a rubber-based photoresist and maintaining a cell gap between the pair of substrates;
A liquid crystal display device comprising:
[0049]
(Appendix 2)
The liquid crystal display device according to claim 1, wherein
The rubber type photoresist is a negative type
A liquid crystal display device characterized by the above-mentioned.
[0050]
(Appendix 3)
The liquid crystal display device according to claim 1 or 2,
The rubber-based photoresist has a resist curing temperature lower than a temperature at which a rubbing effect of an alignment film formed on the facing surfaces of the pair of substrates is impaired.
A liquid crystal display device characterized by the above-mentioned.
[0051]
(Appendix 4)
The liquid crystal display device according to claim 3, wherein
The resist curing temperature is equal to or higher than the temperature of an annealing process for reorienting the liquid crystal.
A liquid crystal display device characterized by the above-mentioned.
[0052]
(Appendix 5)
The liquid crystal display device according to attachment 3 or 4,
The resist curing temperature is 110 ° C. or more and 150 ° C. or less
A liquid crystal display device characterized by the above-mentioned.
[0053]
(Appendix 6)
6. The liquid crystal display device according to any one of supplementary notes 1 to 5, wherein
A sealing material formed on the outer peripheral portions of the pair of substrates and sealing the liquid crystal by curing at a predetermined sealing material curing temperature,
The sealing material curing temperature is lower than a temperature at which the rubbing effect of the alignment film formed on the facing surfaces of the pair of substrates is impaired.
A liquid crystal display device characterized by the above-mentioned.
[0054]
(Appendix 7)
The liquid crystal display device according to attachment 6, wherein
The sealing material curing temperature is equal to or higher than an annealing temperature for reorienting the liquid crystal.
A liquid crystal display device characterized by the above-mentioned.
[0055]
(Appendix 8)
6. The liquid crystal display device according to claim 6, wherein
The sealing material curing temperature is 110 ° C. or more and 150 ° C. or less.
A liquid crystal display device characterized by the above-mentioned.
[0056]
(Appendix 9)
9. The liquid crystal display device according to any one of supplementary notes 6 to 8, wherein
The resist curing temperature is equal to or lower than the sealing material curing temperature.
A liquid crystal display device characterized by the above-mentioned.
[0057]
(Appendix 10)
10. The liquid crystal display device according to any one of supplementary notes 1 to 9,
The columnar spacer has a first adhesive surface adhered to one of the pair of substrates and a second adhesive surface adhered to the other of the pair of substrates.
A liquid crystal display device characterized by the above-mentioned.
[0058]
(Appendix 11)
A first step of forming an uncured columnar spacer made of a rubber-based photoresist on one of the substrates;
A second step of superimposing the one substrate and the other substrate to produce a superimposed substrate;
Curing the uncured columnar spacers to form columnar spacers, and bonding the one substrate and the other substrate to form a bonded substrate;
A method for manufacturing a liquid crystal display device, comprising:
[0059]
(Appendix 12)
The method for manufacturing a liquid crystal display device according to supplementary note 11, wherein
The first step includes a step of applying a rubber-based photoresist on the one substrate to form a resist film, and a step of patterning the resist film.
A method for manufacturing a liquid crystal display device, comprising:
[0060]
(Appendix 13)
In the method for manufacturing a liquid crystal display device according to Supplementary Note 11 or 12,
In the third step, the columnar spacer is bonded to the other substrate.
A method for manufacturing a liquid crystal display device, comprising:
[0061]
(Appendix 14)
14. The method for manufacturing a liquid crystal display device according to any one of supplementary notes 11 to 13, wherein the third step includes heating and curing the uncured columnar spacer at a predetermined heating temperature.
A method for manufacturing a liquid crystal display device, comprising:
[0062]
(Appendix 15)
The method for manufacturing a liquid crystal display device according to supplementary note 14, wherein
Before the second step, further comprising a step of applying a thermosetting sealing material to the outer periphery of the one substrate or the other substrate,
The third step includes a step of heating and curing the sealing material at the heating temperature.
A method for manufacturing a liquid crystal display device, comprising:
[0063]
(Appendix 16)
The method for manufacturing a liquid crystal display device according to supplementary note 15, wherein
In the third step, the uncured columnar spacer is cured almost simultaneously with the sealing material or earlier than the sealing material.
A method for manufacturing a liquid crystal display device, comprising:
[0064]
(Appendix 17)
17. The method for manufacturing a liquid crystal display device according to any one of supplementary notes 14 to 16, wherein the heating temperature is lower than a temperature at which a rubbing effect of an alignment film formed on a facing surface of the superposed substrate is impaired.
A method for manufacturing a liquid crystal display device, comprising:
[0065]
(Appendix 18)
18. The method for manufacturing a liquid crystal display device according to any one of supplementary notes 14 to 17, wherein
The heating temperature is 110 ° C or higher and 150 ° C or lower.
A method for manufacturing a liquid crystal display device, comprising:
[0066]
【The invention's effect】
As described above, according to the present invention, it is possible to realize a liquid crystal display device having strength against external pressure and impact resistance, and having good display characteristics.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a liquid crystal display device according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view illustrating a schematic configuration of a liquid crystal display device according to an embodiment of the present invention.
FIG. 3 is a process sectional view illustrating the method for manufacturing the liquid crystal display according to the embodiment of the present invention.
[Explanation of symbols]
2 TFT substrate
4 Counter substrate
12 Sealing material
20 pillar spacer
21 Uncured columnar spacer
30, 31 Rubber-based photoresist film
80 Gate bus line drive circuit
82 Drain bus line drive circuit
84 control circuit
86, 87 Polarizing plate
88 backlight unit

Claims (5)

A pair of substrates at least one of which is transparent,
Liquid crystal sealed between the pair of substrates,
A liquid crystal display device comprising a columnar spacer formed of a rubber-based photoresist and maintaining a cell gap between the pair of substrates. The liquid crystal display device according to claim 1,
2. The liquid crystal display device according to claim 1, wherein the rubber photoresist is a negative type. The liquid crystal display device according to claim 1, wherein
The liquid crystal display device, wherein the rubber-based photoresist has a resist curing temperature lower than a temperature at which a rubbing effect of an alignment film formed on the facing surfaces of the pair of substrates is impaired. The liquid crystal display device according to claim 3,
The liquid crystal display device, wherein the resist curing temperature is equal to or higher than an annealing temperature for reorienting the liquid crystal. A first step of forming an uncured columnar spacer made of a rubber-based photoresist on one of the substrates;
A second step of superimposing the one substrate and the other substrate to produce a superimposed substrate;
A liquid crystal display comprising: a step of curing the uncured columnar spacer to form a columnar spacer, and bonding the one substrate and the other substrate to produce a bonded substrate. Device manufacturing method.

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