JP4171626B2 - Liquid crystal display - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device in which a substrate gap of a substrate sandwiching a liquid crystal having an optical switch function is maintained constant and uniform over the entire surface of the substrate.
[0002]
[Prior art]
A liquid crystal display device filled with liquid crystal having an optical switch function between glass substrates and other transparent substrates is thinner, lighter and consumes less power than CRT (cathode-ray tube). Widely used as products, display devices for OA equipment, special light modulators, etc.
[0003]
In recent years, an improvement in display response speed of a liquid crystal display device has been demanded in order to display a moving image or the like as smoothly as a CRT. The display response speed depends not only on the type of liquid crystal but also on the distance between two substrates (substrate gap) sandwiching the liquid crystal, and the distance is required to be short and uniform within the substrate surface.
[0004]
Conventionally, in order to maintain the substrate gap, a method has been used in which spherical particles (beads) made of silica or resin are dispersed between the substrates, and the distance between the substrates is kept constant according to the diameter of the beads. According to this method, even if the substrate is pushed in by an external force, the beads can maintain a predetermined substrate gap. However, the dispersed beads do not aggregate and uniformly disperse, and it is difficult to control the disposition of the beads at a predetermined position. Therefore, the beads in the pixel portion cause liquid crystal alignment defects, degrading display quality. . Further, since the beads are not fixed to the two substrates, there is a drawback that when the liquid crystal expands, the substrate gap changes and the display response speed decreases.
[0005]
[Patent Document 1]
JP 2000-155321 A
[Problems to be solved by the invention]
By the way, there has been proposed a method of forming columnar spacers on one substrate other than the pixels by photolithography. According to this method, since no spacer is arranged in the pixel portion, it is possible to prevent the occurrence of alignment defects due to the columnar spacer. However, although one end of the columnar spacer is bonded to the substrate, the other end is not bonded to the superposed substrate, so that the distance between the substrates cannot be kept constant. As a result, the substrate gap changes due to the thermal expansion of liquid crystal, external force, etc., causing problems such as generation of interference fringes, variations in color tone, and variations in drive voltage characteristics.
[0006]
Japanese Laid-Open Patent Publication No. 2000-155321 discloses a liquid crystal display device using columnar spacers whose both ends are bonded to a substrate. According to this publication, the columnar spacer is made of a resin in which spherical or cylindrical beads that are not easily deformed by pressure or heat are dispersed. In the step of laminating the substrates, when the substrates are overlaid and heated, even if the resin portion of the columnar spacer is softened by heat, the substrate gap is maintained by the beads, and the columnar space and the substrate are bonded by the resin. However, if the beads are not uniformly dispersed in the resin, the substrate gap cannot be maintained uniformly. If the bead content is increased, it is difficult to form a uniform thickness during spin coating. Most of them are removed after patterning, which raises costs and causes problems such as poor economy. Further, since the columnar spacer is mostly composed of beads with high hardness, it cannot follow the vibration of the substrate due to impact, particularly when it expands, and the columnar spacer is peeled off from the substrate or the columnar spacer itself is broken. Cause problems.
[0007]
Accordingly, an object of the present invention is to provide a liquid crystal display device capable of improving display quality by maintaining a substrate gap constant and uniform within a substrate surface.
[0008]
[Means for Solving the Problems]
According to one aspect of the present invention, a pair of substrates, a liquid crystal injected between the substrates, a sealing material that seals an outer edge of the substrate, and a spacer that is arranged between the substrates and maintains a substrate gap. Including, The spacer includes a soft resin layer bonded to the substrate and a hard resin layer sandwiched between the soft resin layers and having a higher elastic modulus than the soft resin layer, and the soft resin layer and the hard resin The layer is a thermosetting resin that cures when heated A liquid crystal display device is provided.
[0009]
According to the present invention, a large number of spacers bonded to a pair of substrates are arranged, and the spacers are composed of a plurality of resin layers having different elastic moduli, so that it is possible to follow the thermal expansion and external force of the liquid crystal. The substrate gap can be kept constant. In particular, when the substrate is subjected to an external force, at the instant when the external force is applied to the substrate, the substrate gap once decreases and increases the next moment. Since the spacer of the present invention is formed of resin layers that are bonded to the substrate and have different elastic moduli, the spacer expands and acts on the substrate to be expanded to prevent an excessive increase in the substrate gap. can do. Furthermore, since a large number of spacers are arranged over the entire surface of the substrate, the substrate gap can be maintained uniformly. As a result, variations in display response speed can be suppressed and display quality can be improved.
[0010]
The spacer includes a hard resin layer and a soft resin layer, and the Young's modulus of the soft resin layer having a Young's modulus lower than that of the hard resin layer is 5 × 10 ^-3 It may be in the range of MPa to 1 MPa. Further, the thickness of the soft resin layer may be in the range of 5% to 95% with respect to the thickness of the entire spacer. The flexibility of the spacer can be ensured to follow the thermal expansion and external force of the liquid crystal.
[0011]
An alignment film subjected to a rubbing process is further provided on the opposing surfaces of the pair of substrates, and the thermosetting temperature of each resin layer of the spacer is lower than a temperature at which the effect of the rubbing process of the alignment film is impaired. To do. The sealing material is a thermosetting resin, and the thermosetting temperature of the sealing material is lower than the temperature at which the effect of the rubbing treatment of the alignment film is impaired. By curing each resin layer of the spacer and the sealing material at a temperature that maintains the effect of the rubbing treatment for aligning the liquid crystal, alignment defects and the like can be prevented.
[0012]
The thermosetting temperature of each resin layer of the spacer is not more than the thermosetting temperature of the sealing material. In the laminating process, the resin layers of the spacers arranged on the entire surface of the substrate are first cured at a low temperature, and then the sealing material is cured at the same temperature or higher to fix the outer edge of the substrate. The substrate can be uniformly fixed with a constant substrate gap over the entire surface of the substrate by the spacer.
[0013]
The thermosetting temperature of the sealing material is in the range of 110 ° C to 180 ° C. The thermosetting reaction of the sealing material can be promoted without impairing the effect of the rubbing treatment.
[0014]
According to another aspect of the present invention, a pair of substrates, a liquid crystal injected between the substrates, a sealing material for sealing an outer edge of the substrate, and a plurality of spacers arranged between the substrates and maintaining a substrate gap. And the spacer is bonded to the substrate at both ends, and 5 × 10 ^-3 A liquid crystal display device having a Young's modulus in the range of MPa to 1 MPa is provided.
[0015]
According to the present invention, according to the present invention, a large number of spacers bonded to a pair of substrates are arranged, and the spacers are 5 × 10 5. ^-3 Since it has a Young's modulus in the range of 1 to 1 MPa, it can follow the thermal expansion and external force of the liquid crystal, and the substrate gap can be kept constant. As a result, variations in display response speed can be suppressed and display quality can be improved.
[0016]
The liquid crystal includes a twisted nematic liquid crystal, a super twisted nematic liquid crystal, a nematic cholesteric phase transition liquid crystal, a polymer dispersed liquid crystal, a ferroelectric liquid crystal, an antiferroelectric liquid crystal, a twist grain boundary liquid crystal, and an electric liquid crystal. A structure including at least one liquid crystal in a group of smectic A-phase liquid crystals exhibiting a tilt effect is adopted. The substrate is made of glass, and the substrate gap is 0.1 μm to 6 μm. By using a glass substrate as the substrate, a change in the substrate gap can be suppressed, variation in display response speed in the display range of the liquid crystal display device can be suppressed, and display quality can be improved.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0018]
FIG. 1 is a cross-sectional view showing a schematic configuration of the liquid crystal display device of the present embodiment.
[0019]
Referring to FIG. 1, a liquid crystal display device 10 according to the present embodiment includes two substrates 13 and 14 having a transparent electrode 11 and an alignment film 12 formed on the inner surface, and a liquid crystal sandwiched between the substrates 13 and 14. 15, a large number of spacers 16 for keeping the substrate gap constant, a sealing material 18 for sealing the liquid crystal, and the like.
[0020]
For the substrates 13 and 14, for example, a glass substrate having a thickness of 0.5 mm to 1.25 mm, such as non-alkali glass or silica glass, is used. A transparent electrode 11 is formed on the lower substrate 13. The transparent electrode 11 is made of, for example, ITO (indium / tin / oxide) and is formed in a striped pattern in one direction. The alignment film 12 formed on the transparent electrode 11 is made of polyimide having a thickness of 60 nm to 200 nm, for example, and the surface thereof is rubbed. On the other hand, a color filter (not shown) is formed on the upper substrate 14 below the glass substrate. The color filter is composed of three color filters of RGB and a black matrix. Under the color filter, the transparent electrode 11 is formed with a striped electrode in the vertical direction with respect to the transparent electrode 11 of the lower substrate. Under this, an alignment film 12 is formed.
[0021]
The liquid crystal 15 includes a twisted nematic liquid crystal, a super twisted nematic liquid crystal, a nematic cholesteric phase transition liquid crystal, a polymer dispersed liquid crystal, a ferroelectric liquid crystal, an antiferroelectric liquid crystal, a twist grain boundary liquid crystal, A smectic A phase liquid crystal exhibiting a tilting effect can be used. In particular, a ferroelectric liquid crystal having a high display response speed is suitable for the liquid crystal display device of the present embodiment.
[0022]
The spacer 16 has, for example, a cylindrical shape, and is set to have a diameter of 1 μm to 20 μm and a height of 0.1 μm to 6 μm, for example. However, the shape may be a prism, a pyramid, a cone, or the like, and the shape is not limited. The spacer 16 is composed of a resin layer using photoresists having different elastic moduli. As shown in FIG. 1, the three resin layers 16A and 16B are a layer having a high modulus of elasticity after curing, for example, a layer 16A having a high Young's modulus (hereinafter referred to as “hard resin layer”) and a layer having a low Young's modulus after curing. 16B (hereinafter referred to as “soft resin layer”). Specifically, the spacer 16 shown in FIG. 1 has a hard resin layer 16A / soft resin 16B / hard resin layer 16A from the bottom. The spacer is, for example, 20 pieces / mm with respect to the substrate area. ² ~ 200 / mm ² Set to
[0023]
As the photoresist of the hard resin layer 16A, a positive photoresist such as a polyimide resin, a phenol resin, a novolac resin, an acrylic resin, or the like can be used. On the other hand, as the photoresist of the soft resin layer 22, for example, polysilane, polycarbosilane, and polysiloxane resin can be used. A polysiloxane-based resist in which Si and oxygen are bonded is preferable in that the main chain of the polymer is a short bond and is three-dimensional and thus has high stretchability and low Young's modulus. Furthermore, a solder resist can be used as the photoresist of the soft resin layer 22. Solder resist is, for example, partially acrylated resin of epoxy resin, epoxy resin such as resin combining linear polymer and acrylic oligomer, photo depolymerization type modified with various polymers, resin with shared chalcone group and epoxy group A photo-dimerization type alone or in combination with a thermosetting resin such as an epoxy resin is included in a resin and contains a photodepolymerization initiator, a curing agent, and the like, and has ultraviolet curing and thermosetting properties. In addition, by using a positive resist for these resists, the exposed part changes to a structure that is depolymerized or soluble in the developer, and the unexposed part remains by development using a basic solution, and the unexposed part becomes a spacer. It becomes 16 and is thermoset by heating described later.
[0024]
The photoresist for the hard resin layer 16A and the soft resin layer 16B is selected so that the thermosetting temperature is not higher than the temperature at which the effect of rubbing the alignment film is not impaired. When the effect of the rubbing treatment is impaired, the alignment of the liquid crystal is disturbed, and it can be determined by assembling and driving the liquid crystal display device. The thermosetting temperature of the photoresist is preferably in the range of 110 ° C to 180 ° C, and more preferably in the range of 110 ° C to 150 ° C. The upper limit of 180 ° C. is a temperature that does not impair the rubbing effect in consideration of the heating temperature distribution in the laminating step described later, and the lower limit is 110 ° C. This is because the reaction needs to be completed within a predetermined heating time. Here, the thermosetting temperature can be quantified by, for example, FT-IR analysis.
[0025]
The soft resin layer 16B has a Young's modulus lower than that of the hard resin layer 16A. The Young's modulus after curing of the soft resin layer 22 is 5 × 10 5 at 25 ° C. to 120 ° C. ^-3 It is preferably in the range of MPa to 1 MPa. Young's modulus is 5 × 10 ^-3 If it is smaller than MPa, it causes fluctuations in the substrate gap, and if it is larger than 1 MPa, it becomes impossible to follow the volume change of the liquid crystal. Since the soft resin layer 16B has such characteristics, the spacer 16 can follow the change in the substrate gap due to the change in volume of the liquid crystal due to the thermal expansion and contraction of the liquid crystal. , 14, and the like, and the substrate gap can be maintained in a desired range. The Young's modulus of the entire spacer 16 varies depending on the ratio of the thickness of the soft resin layer 16B and the hard resin layer 16A, but the Young's modulus of the hard resin layer 21 is 5 times the Young's modulus of the soft resin layer 16B. Since it is 20 times, the Young's modulus of the entire spacer 16 is almost equal to the Young's modulus of the soft resin layer 16B.
[0026]
The thickness of the soft resin layer 16B is set to 5% to 95% with respect to the thickness of the entire spacer 16. If it exceeds 95%, the thickness of the hard resin layer 16A with good adhesiveness is reduced, and the adhesion to the substrates 13, 14 or the alignment film 12 may be insufficient. If it is less than 5%, sufficient flexibility is obtained. I can't.
[0027]
The coefficient of thermal expansion of the spacer 16 is preferably substantially equal to the coefficient of thermal expansion of the liquid crystal described above from the viewpoint of preventing the spacer 16 from breaking or peeling from the substrates 13 and 14.
[0028]
The sealing material 18 is applied to the periphery of the substrate and is made of, for example, a thermosetting resin or a photocurable resin having a thickness of 2 μm to 10 μm. It is applied to the periphery of the substrate with a width of about 1 mm to prevent the substrate gap and the displacement in the substrate surface, and also prevent the liquid crystal from leaking. In addition, a liquid crystal injection port (not shown) for filling the liquid crystal in a part of the sealing material 18 is provided.
[0029]
Hereinafter, a manufacturing process of the liquid crystal display device of the present embodiment will be described.
[0030]
2A to 2C and FIGS. 3D to 3E are diagrams showing a manufacturing process of the liquid crystal display device of the present embodiment.
[0031]
In the step of FIG. 2A, transparent electrodes are formed on the substrates 13 and 14. Specifically, an ITO layer having a thickness of, for example, 50 nm is formed on a substrate such as a glass substrate by sputtering, ion plating, electron beam, or the like. Next, the striped transparent electrode 11 is formed by patterning with a photoresist. An insulating film such as a silicon oxide film is formed between the electrodes.
[0032]
In the step of FIG. 2A, an alignment film 12 is further formed on the transparent electrode 11, and a rubbing process is performed. Specifically, for example, a polyimide material having a thickness of 0.1 μm or less is applied by spin coating, printing, or the like, and is heated and cured at 180 ° C. to 200 ° C. Next, the surface of the alignment film is rubbed in the alignment direction of the liquid crystal molecules with a roller made of nylon or the like. Similarly, a transparent electrode 11 and an alignment film are formed on the other substrate 14 and a rubbing process is performed.
[0033]
In the step of FIG. 2B, three layers of a positive photoresist film are applied over the structure of FIG. 2A, and the spacers 16 are formed by etching. Specifically, first, the resist film 21 to be the hard resin layer 16A is set in a thickness range of 0.1 μm to 6 μm (preferably 0.1 μm to 3 μm) by, for example, a spin method, a slit and spin method, or the like. Apply. Next, in order to evaporate the solvent remaining in the resist, prebaking is performed at about 100 ° C. for 1 to 3 minutes in a clean oven or the like. Next, the resist film 22 to be the soft resin layer 16B is applied in the same manner with a thickness in the range of 0.1 μm to 6 μm (preferably 0.1 μm to 3 μm). Next, prebaking is performed in the same manner, and a resist film 21 to be the hard resin layer 16A is set to the same thickness and applied. By these pre-baking, the adhesion between the resist film 21 and the alignment film 12 formed on the substrate 13 proceeds, and the adhesion becomes stronger.
[0034]
Next, in the step of FIG. 2C, the resist 16 is patterned by photolithography to form the spacers 16. Specifically, a mask 23 that shields light from the portion of the spacer 16 is prepared so that the spacer 16 is formed in the portion corresponding to the black matrix of the color filter. For example, in a color filter having a pitch of 80 μm, the width of the black matrix is about 13 μm. Therefore, the diameter of the spacer 16 is preferably set to 10 μm or less in consideration of the deviation of the upper and lower substrate alignment. The protrusion of the spacer 16 to the pixel portion can be prevented, and the display quality can be maintained. Next, the mask 23 is used for exposure with ultraviolet light or the like by a stepper.
[0035]
Next, in the step of FIG. 3D, the exposed substrate is developed with a basic aqueous solution or the like. The exposed exposed resist is removed, and the substrate surface is washed and rinsed with pure water and dried. Thus, the spacer 16 is formed. Since the spacer 16 is formed of a photoresist, the height is uniform over the entire substrate, and the thicknesses of the three resist layers are also uniform. Therefore, there is an advantage that the substrate gap can be maintained uniformly over the entire display region. In addition, when a three-layer or more multilayer structure is used in this way, it is preferable to use a resist with high sensitivity because the amount of light decreases in the lower layer far from the light source. For example, in the present embodiment, it is preferable to use a photoresist having a high photosensitivity for the photoresist of the soft resin layer 22.
[0036]
In the step of FIG. 3D, the sealing material 18 is further applied, the other glass substrate 14 is overlapped, and the two substrates 13 and 14 are bonded and fixed by applying pressure and heating. Specifically, a seal material 18 made of a thermosetting resin is applied to the periphery of the surface on which the spacer 16 is formed to a width of about 1 mm by a printing method or the like. The sealing material 18 may be not only a thermosetting resin but also a photocurable resin such as an ultraviolet curable resin. Note that a portion where the sealing material 18 is not applied is provided as a liquid crystal injection port.
[0037]
Next, the transparent electrodes 11 and the spacers 16 and the color filters are aligned with each other by a bonding apparatus or the like, and are fixed to a jig. Further, pressure is applied uniformly from both sides of the substrate to bond one end of the spacer 16 to the substrate and to heat the seal material 18 for thermosetting.
[0038]
Next, the stacked substrates are bonded by heating at about 150 ° C. for 1 hour in a clean oven or the like. Specifically, the spacer 16 is first softened and further adhered to the alignment film 12 of the substrates 13 and 14 by curing polymerization or the like. Since the entire substrate 13, 14 is uniformly pressed by the jig, the substrate gap is maintained constant over the entire surface of the substrate and is supported and fixed by the spacer 16. When the sealing material 18 is a thermosetting resin, the sealing material 18 is thermoset after the spacers 16 are bonded. This is because the curing speed of the sealing material 18 is set slower than that of the spacer 16. Accordingly, since the sealing material 18 is cured after the spacer 16 is bonded to the substrate, excessive stress does not remain on the substrate. If this heating temperature is too high, the effect of the rubbing treatment applied to the alignment film is impaired, so that the heating temperature is preferably 180 ° C. or lower (more preferably 110 ° C. to 150 ° C.). Note that the heating temperature may be set in two stages, each resin layer of the spacer may be cured at a low temperature, and then the sealing material may be cured at a higher temperature. Thus, the substrates 13 and 14 (hereinafter referred to as “liquid crystal panel 20”) bonded by the spacer 16 and the sealing material are formed.
[0039]
In the step of FIG. 3E, liquid crystal is injected into the liquid crystal panel 20 by the bell jar shown in FIG. 4 by vacuum injection. FIG. 4 is a diagram showing a schematic configuration of the bell jar. Referring to FIG. 4, the bell jar 30 includes a vacuum chamber 31 capable of reducing the pressure inside, a liquid crystal reservoir 32 for supplying the liquid crystal 15 disposed in the vacuum chamber 31, and a transport mechanism 33 that transports the liquid crystal panel 20. The intake / exhaust ports 35 and 36 are configured. First, the liquid crystal panel 20 is disposed in the vacuum chamber 31, and is exhausted from the exhaust port 36 by a vacuum pump (not shown) or the like to reduce the pressure, and the air in the liquid crystal panel 20 into which the liquid crystal 15 is injected is exhausted. Next, the liquid crystal injection port 19 is immersed in the liquid crystal 15 of the liquid crystal reservoir 32 and nitrogen, air, or the like whose flow rate is adjusted is introduced into the vacuum chamber 31 through the intake port 35, and the pressure is gradually increased. The liquid crystal 15 is injected into the liquid crystal panel 20 by the pressure and the pressure difference in the vacuum chamber 31.
[0040]
Finally, the liquid crystal injection port 19 is sealed. Thus, the liquid crystal display device 10 of the present embodiment is formed.
[0041]
Note that a dropping method can be used instead of the vacuum injection method described in the step of FIG. When the dropping method is used, after applying the sealing material 18 described with reference to FIG. 3D, the liquid crystal is formed into droplets using a dispenser and placed on the substrate, for example. At this time, the liquid droplets are arranged so that the liquid crystal does not adhere to the spacer 16. Adhesiveness of the spacer 16 can be ensured.
[0042]
According to the present embodiment, as described above, the two substrates of the liquid crystal display device are bonded and held by the spacer having a three-layer structure of hard resin layer / soft resin layer / hard resin layer. Since the Young's modulus is set lower than that of the hard resin layer, the drag that follows the change in the substrate gap due to the thermal expansion of the liquid crystal and the rapid change in the substrate gap due to impact such as external force and suppresses the change in the substrate gap Acts on the substrate. Therefore, it is possible to maintain the substrate gap constant and uniform, and as a result, it is possible to suppress display response speed variations and improve display quality.
[0043]
FIG. 5 is a diagram showing a liquid crystal display device which is a modification of the present embodiment. In the figure, portions corresponding to the portions described above are denoted by the same reference numerals, and description thereof is omitted.
[0044]
Referring to FIG. 5, the liquid crystal display device 40 of this modification is the same as that of the present embodiment except that the spacer 46 is formed of one soft resin layer. As the soft resin layer, the above-described resins can be used, and a silicone resist is preferable from the viewpoint of adhesion to the alignment film 11 or the substrates 13 and 14. The Young's modulus after the soft resin layer is cured under the above-mentioned heating conditions for substrate bonding is 5 × 10 5 at a temperature of 25 ° C. to 120 ° C. ^-3 It is preferably in the range of MPa to 1 MPa.
[0045]
According to this modification, since the spacer is formed of one soft resin layer, the number of resist forming steps can be reduced.
[0046]
Examples of the liquid crystal display device of the present invention will be described below.
[0047]
[First embodiment]
A polyimide solution was applied to each of two glass substrates having a transparent electrode size of 200 × 100 mm and a thickness of 1.1 mm by spin coating. A polyimide solution (concentration: 3% by mass, manufactured by Nippon Shokubai Co., Ltd.) was used and applied at a rotational speed of 2000 rpm. Next, baking was performed at 200 ° C. for 30 minutes, and the film thickness of the alignment film was 100 nm. The alignment film was rubbed by a known method.
[0048]
Next, a positive type photoresist (trade name: AZ-5200, manufactured by Cleart Co., Ltd.) serving as a hard resin layer was used on the alignment film of one glass substrate, and the thickness was set to 1 μm by spin coating. . Pre-baking was performed at 100 ° C. for 1 minute in a clean oven to evaporate the solvent remaining in the photoresist. Next, using a positive photoresist (manufactured by Nippon Paint Co., Ltd., trade name: Gracia) to be the soft resin layer 22, it was applied by setting the thickness to 1 μm by spin coating. Pre-baked in the same manner as described above, and further applied using the same positive photoresist as that of the hard resin layer (trade name: AZ-5200, manufactured by Cleint Co., Ltd.) by spin coating to a thickness of 1 μm. . Thus, a photoresist laminate having a thickness of 3 μm and a three-layer structure of hard resin layer / soft resin layer / hard resin layer was formed.
[0049]
Next, using a mask in which cylindrical spacers having a diameter of 10 μm are formed at intervals of 100 μm, exposure and development are performed using ultraviolet light, and the surface is washed with pure water and dried to form columnar spacers having a height of 3 μm. It was done.
[0050]
An epoxy resin (trade name: KAYATORON, manufactured by Nippon Kayaku Co., Ltd.) serving as the sealing material 18 was applied to a glass substrate on which columnar spacers were formed to a thickness of 5 μm by a printing method. The liquid crystal injection port was not coated. The pair of glass substrates were bonded together by aligning corresponding portions of the transparent electrode, placed in a vacuum bag, evacuated, and heated at 150 ° C. for 1 hour. The spacer was bonded to the bonded substrate, and the epoxy resin of the sealing material was cured. When the substrate gap was measured, it was 1.5 μm.
[0051]
In this liquid crystal panel, the ferroelectric liquid crystal was injected through the liquid crystal injection port by the method described in the above embodiment, and the liquid crystal injection port was sealed. Thus, the liquid crystal display device of this example was formed.
[0052]
The liquid crystal display device of this example is inserted between two polarizing plates in a crossed Nicol state, and a ballpoint pen with a ball diameter (diameter) of 0.8 mm is used to vertically display a liquid crystal display with a force of 0.98 N (100 gf). When the center of the device was pressed, no change in brightness was observed around the nib. Therefore, it was found that there is stress with respect to the external force that reduces the liquid crystal layer thickness. The liquid crystal display device is in a normally white state.
[0053]
In addition, when the central portion of the liquid crystal display device of this embodiment is supported and fixed, and the above-described ball-point pen is used to push the liquid crystal vertically with a force of 2.94 N (300 gf), no change in brightness is observed. It was.
[0054]
Further, the liquid crystal display device of this example was left in an environment of −40 ° C. for 1 hour, and the above two tests were performed. In both tests, no change in brightness was observed. Further, no change was observed in the display quality of the liquid crystal, and the followability to the volume change due to the thermal contraction of the liquid crystal was confirmed.
[0055]
In addition, for the liquid crystal display device of this example, the Young's modulus of a three-layer spacer heated at 150 ° C. for 1 hour, which is the same as the heating condition of the liquid crystal display device of this example, was measured before the glass substrate was bonded. did. Young's modulus is 9 × 10 in the temperature range of 25 ° C. to 120 ° C. ^-1 MPa-9 × 10 ^-3 MPa. Furthermore, when the spacer of only the soft resin layer was measured, the Young's modulus was 7 × 10 in the temperature range of 25 ° C. to 120 ° C. ^-2 MPa-9 × 10 ^-3 MPa. The measurement was performed using a thermal analysis rheology system (trade name EXSTAR6000, manufactured by Seiko Denshi Kogyo Co., Ltd.), and the measurement conditions were measured from 25 ° C. at a rate of temperature increase of 10 ° C./min and a frequency of 10 Hz to determine the storage elastic modulus The Young's modulus was calculated from the numerical value.
[0056]
[Second Embodiment]
The second embodiment is the same as the first embodiment except that a solder resist (trade name SK-66, manufactured by Shin-Etsu Silicone Co., Ltd.) is used as a positive photoresist to be a soft resin layer, compared to the first embodiment. A liquid crystal display device was produced in the same manner.
[0057]
As a result of performing the same test as in the first example, the same result as in the first example was obtained, and a good result was obtained.
[Third to eighth embodiments]
In the third to eighth embodiments, the liquid crystal is twisted nematic (TN) type liquid crystal (third embodiment) and super twisted nematic (STN) type liquid crystal (fourth embodiment). , Nematic cholesteric liquid crystal (fifth embodiment), antiferroelectric liquid crystal (sixth embodiment), twist grain boundary type liquid crystal (seventh embodiment), and smectic A phase (eighth embodiment). A liquid crystal display device was fabricated in the same manner as in the first example except for the change.
[0058]
As a result of performing the same test as in the first example, the same results as in the first example were obtained in all of the third to eighth examples, and good results were obtained.
[Ninth embodiment]
The ninth embodiment has a two-layer structure in which the first resin layer is a soft resin layer (Nippon Paint Gracia) and the second layer is a hard resin layer (Clint AZ-5200). A liquid crystal display device was manufactured in the same manner as in the first example except that the layer thicknesses were 4.75 μm and 0.25 μm, respectively.
[0059]
As a result of performing the same test as in the first example, the same result as in the first example was obtained, and a good result was obtained.
[Tenth embodiment]
In the tenth embodiment, the total thickness of the three-layered photoresist is 5 μm, and the hard resin layer / soft resin layer / hard resin layer thickness is 2 μm / 0.25 μm / 2. A liquid crystal display device was produced in the same manner as in the first example except that the thickness was 75 μm.
[0060]
As a result of performing the same test as in the first example, the same result as in the first example was obtained, and a good result was obtained.
[11th to 18th embodiments]
In the first to eighteenth embodiments, the first to eighth embodiments are different from the first to eighth embodiments except that the total thickness of the three-layered photoresist is 6 μm and the thickness of each layer is 2 μm. A liquid crystal display device was produced in the same manner as in the example.
[0061]
As a result of performing the same test as in the first example, the same results as in the first example were obtained in all of the first to eighteenth examples, and good results were obtained.
[Nineteenth embodiment]
In the nineteenth embodiment, in contrast to the first embodiment, a liquid crystal display device is manufactured in the same manner as in the first embodiment except that a liquid crystal injection method uses a dropping method instead of a vacuum injection method and a liquid crystal is supplied to a glass substrate by a dispenser. Produced.
[0062]
In the dropping method, before bonding the glass substrates, an epoxy resin to be the sealing material 18 was applied to one glass substrate to a thickness of 3 μm by a printing method, and then a ferroelectric liquid crystal was dropped by a dispenser. Subsequent steps were performed in the same manner as in the first example to produce a liquid crystal display device.
[0063]
As a result of performing the same test as in the first example, the same result as in the first example was obtained, and a good result was obtained.
Hereinafter, comparative examples for the present invention will be described.
[0064]
[First comparative example]
In the first comparative example not according to the present invention, a liquid crystal display device was produced in the same manner as in the first example, except that the spacer was formed only by the hard resin layer without providing the soft resin layer with respect to the first example. .
[0065]
In the spacer, the thickness of the hard resin layer was set to 3 μm, and the substrate gap after bonding the substrates was 1.5 μm. The spacer is formed only on the hard resin layer. The test was performed in the same manner as in the first example.
[0066]
The liquid crystal display device of this comparative example is inserted between two polarizing plates in a crossed Nicols state, and a vertical liquid crystal display is performed with a force of 0.98 N (100 gf) using a ballpoint pen having a ball diameter (diameter) of 0.8 mm. When the center of the device was pressed, no change in brightness was observed around the nib. Therefore, it was found that there is stress resistance against an external force that reduces the liquid crystal layer thickness.
[0067]
In addition, when the central portion of the liquid crystal display device of this comparative example is supported and fixed, and the above-described ballpoint pen is used to push the liquid crystal vertically with a force of 2.94 N (300 gf), no change in brightness is observed. It was.
[0068]
Furthermore, the liquid crystal display device of this comparative example was left in an environment of −40 ° C. for 1 hour, and the above two tests were performed. In both tests, changes in brightness were observed, and the phenomenon that the liquid crystal layer was disturbed and the display quality deteriorated was observed. This is considered to have occurred because the liquid crystal panel could not follow the contraction change when the liquid crystal volume changed due to the temperature environment.
[0069]
In addition, regarding the liquid crystal display device of this comparative example, the Young's modulus of the spacer with a single layer structure heated at 150 ° C. for 1 hour, which is the same as the heating condition of the liquid crystal display device of this comparative example, before the glass substrate is bonded. It was measured. The Young's modulus was 5 MPa to 2 MPa in the temperature range of 25 ° C to 120 ° C.
[Second Comparative Example]
The second comparative example not according to the present invention produces a liquid crystal display device in the same manner as in the first example except that the heating temperature for curing the sealing material 18 is 190 ° C., compared to the first example. did.
[0070]
In the liquid crystal display device of this comparative example, disorder of alignment was observed and a reduction in display quality was observed. It is considered that the heating temperature was high and the rubbing effect of the alignment film was partly damaged by heat.
[0071]
Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the present invention described in the claims. Is possible.
[0072]
In the embodiment, the example in which the hard resin layer 16A is bonded to the alignment film on the substrate has been described. However, the soft resin layer 16B may be bonded to the alignment film on the substrate. That is, the spacer 16 may have a hard resin layer 16A / soft resin layer 16B configuration, or may have a soft resin layer 16B / hard resin layer 16A / soft resin layer 16B configuration.
[0073]
In addition, the following additional notes are disclosed regarding the above description.
(Supplementary note 1) a pair of substrates;
Liquid crystal injected between the substrates;
A sealing material for sealing an outer edge of the substrate;
A plurality of spacers arranged between the substrates and maintaining a substrate gap;
Including
The liquid crystal display device, wherein both ends of the spacer are bonded to the substrate and are made of a plurality of resin layers having different elastic moduli.
(Additional remark 2) The said spacer consists of a hard resin layer and a soft resin layer, and the Young's modulus of the said soft resin layer whose Young's modulus is lower than the said hard resin layer is 5x10. ^-3 2. The liquid crystal display device according to supplementary note 1, wherein the liquid crystal display device is in a range of MPa to 1 MPa.
(Additional remark 3) The thickness of the said soft resin layer is the range of 5%-95% with respect to the thickness of the whole spacer, The liquid crystal display device of Additional remark 2 characterized by the above-mentioned.
(Additional remark 4) The alignment film by which the rubbing process was given to the opposing surface of a pair of said board | substrate is further provided, and the thermosetting temperature of each resin layer of the said spacer is the temperature at which the effect of the rubbing process of the said alignment film is impaired The liquid crystal display device according to claim 1, wherein the liquid crystal display device is lower.
(Additional remark 5) The thermosetting temperature of each resin layer of the said spacer is the range of 110 to 180 degreeC, The liquid crystal display device as described in any one of Additional remarks 1-4 characterized by the above-mentioned.
(Appendix 6) The liquid crystal display according to appendix 4 or 5, wherein the sealing material is a thermosetting resin, and the thermosetting temperature of the sealing material is lower than a temperature at which the effect of rubbing treatment of the alignment film is impaired. apparatus.
(Supplementary note 7) The liquid crystal display device according to any one of supplementary notes 4 to 6, wherein the thermosetting temperature of each resin layer of the spacer is equal to or lower than the thermosetting temperature of the sealing material.
(Supplementary Note 8) The liquid crystal display device according to any one of Supplementary Notes 4 to 7, wherein a thermosetting temperature of the sealing material is in a range of 110 ° C to 180 ° C.
(Additional remark 9) The said soft resin layer consists of at least 1 resist among the group of a polysilane type resist, a polycarbosilane type resist type resist, and a polysiloxane type resist. A liquid crystal display device according to claim 1.
(Supplementary note 10) The liquid crystal display device according to any one of supplementary notes 2 to 8, wherein the soft resin layer is made of a solder resist.
(Additional remark 11) The said soft resin layer consists of positive resists, The liquid crystal display device as described in any one among Additional remarks 2-10 characterized by the above-mentioned.
(Supplementary note 12) a pair of substrates;
Liquid crystal injected between the substrates;
A sealing material for sealing an outer edge of the substrate;
A plurality of spacers arranged between the substrates and maintaining a substrate gap;
Including
Both ends of the spacer are bonded to the substrate, and 5 × 10 ^-3 A liquid crystal display device having a Young's modulus in a range of MPa to 1 MPa.
(Supplementary Note 13) The liquid crystal is a twisted nematic liquid crystal, a super twisted nematic liquid crystal, a nematic cholesteric phase transition liquid crystal, a polymer dispersed liquid crystal, a ferroelectric liquid crystal, an antiferroelectric liquid crystal, a twist grain, 13. The liquid crystal display device according to any one of appendices 1 to 12, wherein the liquid crystal display device includes at least one liquid crystal selected from a group of boundary liquid crystals and smectic A phase liquid crystals exhibiting an electroclinic effect.
(Supplementary note 14) The liquid crystal display device according to supplementary note 13, wherein the spacer includes at least one resist selected from the group consisting of a polysilane resist, a polycarbosilane resist resist, and a polysiloxane resist.
(Additional remark 15) The said spacer contains a soldering resist, The liquid crystal display device of Additional remark 13 characterized by the above-mentioned.
(Supplementary note 16) The liquid crystal display device according to any one of supplementary notes 1 to 15, wherein the substrate is made of glass, and a substrate gap is 0.1 μm to 6 μm.
(Supplementary Note 17) A pair of first and second substrates;
Liquid crystal injected between the substrates;
A sealing material for sealing an outer edge of the substrate;
A plurality of spacers arranged between the substrates and maintaining the substrate gap;
A method for manufacturing a liquid crystal display device comprising:
Forming a plurality of resist layers on the first substrate;
Patterning the resist layer to form spacers;
A bonding step in which the sealing material is applied to an outer edge of the first or second substrate, and the first and second substrates are stacked and pressed;
A heating step in which the resist layer of the spacer is cured while being pressurized and bonded to the second substrate, and the sealing material is cured;
Injecting liquid crystal into the bonded substrate by vacuum injection;
A method for manufacturing a liquid crystal display device comprising:
(Supplementary Note 18) A pair of first and second substrates;
Liquid crystal injected between the substrates;
A sealing material for sealing an outer edge of the substrate;
A plurality of spacers arranged between the substrates and maintaining the substrate gap;
A method for manufacturing a liquid crystal display device comprising:
Forming a plurality of resist layers on the first substrate;
Patterning the resist layer to form spacers;
Applying the sealing material to the outer edge of the first or second substrate and filling the liquid crystal by a dropping method;
A step of superposing and pressing the first and second substrates;
A heating step in which the resist layer of the spacer is cured while being pressurized and bonded to the second substrate, and the sealing material is cured;
A method for manufacturing a liquid crystal display device comprising:
(Additional remark 19) The manufacturing time of the liquid crystal display device of Additional remark 17 or 18 characterized by the heating time in the said heating process being less than 2 hours.
[0074]
【The invention's effect】
As is clear from the above detailed description, according to the present invention, since the spacer made of the resin layer is bonded to the inner surface of the substrate and the soft resin layer of the spacer has a low elastic modulus, On the other hand, it is possible to provide a liquid crystal display device in which the substrate can follow and the display gap can be improved by maintaining the substrate gap constant and uniform within the substrate surface.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a schematic configuration of a liquid crystal display device according to an embodiment of the present invention.
FIGS. 2A to 2C are diagrams illustrating a manufacturing process (part 1) of a liquid crystal display device according to an embodiment; FIGS.
FIGS. 3D to 3E are diagrams showing a manufacturing process (No. 2) of the liquid crystal display device according to the embodiment; FIGS.
FIG. 4 is a diagram showing a schematic configuration of a bell jar by a vacuum injection method.
FIG. 5 is a cross-sectional view showing a schematic configuration of a liquid crystal display device according to a modification of the embodiment of the present invention.
[Explanation of symbols]
10, 40 Liquid crystal display device
11 Transparent electrode
12 Alignment film
13, 14 substrate
15 LCD
16, 46 Spacer
16A hard resin layer
16B Soft resin layer
18 Sealing material
21, 22 Resist film

Claims (9)

A pair of substrates;
Liquid crystal injected between the substrates;
A sealing material for sealing an outer edge of the substrate;
A plurality of spacers arranged between the substrates and maintaining a substrate gap;
Including
The spacer, a soft resin layer bonded to each of the substrate, Ri Na more and the soft resin layer high hard resin layer having an elastic modulus than sandwiched between the soft resin layer,
The liquid crystal display device, wherein the soft resin layer and the hard resin layer are thermosetting resins that are cured by applying heat . The soft resin layer has a lower Young's modulus than the hard resin layer,
The liquid crystal display device according to claim 1, wherein a Young's modulus of the soft resin layer is in a range of 5 × 10 ⁻³ MPa to 1 MPa.   3. The liquid crystal display device according to claim 1, wherein the thickness of the soft resin layer is in the range of 5% to 95% with respect to the thickness of the entire spacer.   An alignment film subjected to a rubbing process is further provided on the opposing surfaces of the pair of substrates, and the thermosetting temperature of each resin layer of the spacer is lower than a temperature at which the effect of the rubbing process of the alignment film is impaired. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is a liquid crystal display device.   The liquid crystal display device according to claim 4, wherein the sealing material is a thermosetting resin, and a thermosetting temperature of the sealing material is lower than a temperature at which an effect of rubbing the alignment film is impaired.   6. The liquid crystal display device according to claim 4, wherein the heat curing temperature of each of the soft resin layer and the hard resin layer is equal to or lower than the heat curing temperature of the sealing material.   7. The liquid crystal display device according to claim 4, wherein the sealing material has a thermosetting temperature in a range of 110 ° C. to 180 ° C. 7.   The liquid crystal includes a twisted nematic liquid crystal, a super twisted nematic liquid crystal, a nematic cholesteric phase transition liquid crystal, a polymer dispersed liquid crystal, a ferroelectric liquid crystal, an antiferroelectric liquid crystal, a twist grain boundary liquid crystal, and an electric liquid crystal. The liquid crystal display device according to claim 1, comprising at least one liquid crystal in a group of smectic A phase liquid crystals exhibiting a tilt effect.   The liquid crystal display device according to claim 1, wherein the substrate is made of glass, and the substrate gap is 0.1 μm to 6 μm.

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