JP5150182B2 - Manufacturing method of liquid crystal display device - Google Patents

Description

  The present invention relates to a liquid crystal display device, and more particularly to a transflective liquid crystal display device and a manufacturing method thereof.

  Patent Document 1 describes a transflective IPS (In Plane Switching) type liquid crystal display device that applies a lateral electric field to a liquid crystal layer. This transflective liquid crystal display device is not limited to the IPS system, and for example, a TN (Twisted Nematic) system or a VA (Vertical Alignment) system is used in one pixel. There are a transmissive display portion and a reflective display portion. The reflective display portion of the transflective liquid crystal display device exemplified in Patent Document 1 is formed with a built-in retardation plate having a retardation of half wavelength. Furthermore, in this transflective liquid crystal display device, the retardation of the liquid crystal layer of the reflective display section is adjusted to a quarter wavelength, enabling reflective display in a wide range of environments including bright places to dark places, In addition, it enables high-quality transmissive display with a wide viewing angle. The built-in retardation plate is formed of molecules exhibiting birefringence such as liquid crystal molecules.

  In such a liquid crystal display device, an RGB resist layer, a flattening layer for flattening the RGB resist layer, an alignment film for aligning the built-in retardation plate, and the alignment film are provided on the substrate on the color filter side. The aligned built-in retardation plate and the alignment film for aligning the liquid crystal layer are stacked in this order.

  Therefore, in the manufacturing process, in order to form an alignment film for aligning the built-in phase difference plate, for example, a process of coating and baking a polyimide organic material and performing an alignment process by a rubbing method is required.

JP-A-2005-338256

  In mass production of transflective liquid crystal display devices (especially IPS liquid crystal display panels), cost reduction and manufacturing time are eagerly desired, and it is desired to reduce manufacturing process steps.

  An object of the present invention is to reduce the number of manufacturing process steps in a transflective liquid crystal display device.

  In order to solve the above-described problems, in the present invention, an alignment regulating force is given to a portion where a retardation plate of a planarizing layer for planarizing a colored resist layer is disposed. And the formation process of an orientation film is omitted by making the part into the base layer of a phase difference plate.

According to a first aspect of the present invention , a liquid crystal layer is sealed between a main surface in which a retardation plate of a first substrate is incorporated and a second substrate, and a transflective device including a reflective display portion and a transmissive display portion is provided. Type liquid crystal display device manufacturing method, comprising: applying a photocurable resin composition to be a base layer of the retardation plate to a main surface of the first substrate; and applying the mask layer by the mask exposure The photocurable resin composition is partially cured, and after the curing process, a development process is performed to remove an uncured portion of the photocurable resin composition, and the cured photocurable resin composition is applied to the cured photocurable resin composition. A base layer curing step for forming a region having unevenness by removing the uncured portion and a flat region not having the unevenness, the region having the unevenness on the cured photocurable resin composition, and the Apply the retardation plate material to a flat area and heat cure. A phase difference plate forming step for forming a phase difference plate that is oriented by the orientation regulating force of the irregularity in the region where the unevenness is formed, and a residual layer that is not oriented in the flat region; and the phase difference plate and the phase difference plate An alignment film forming step for forming an alignment film for aligning the liquid crystal layer on the remaining layer is performed in this order.

In the second aspect of the present invention, in the base layer curing step, the mask exposure is performed so that the exposed portions and the non-exposed portions are alternately arranged in a line in the region where the unevenness is formed, A plurality of aligned grooves are formed as the unevenness.

The third aspect of the present invention is characterized in that the uneven region is formed in the reflective display portion, and the flat region is formed in the transmissive display portion.

  A liquid crystal display device to which an embodiment of the present invention is applied will be described below.

  FIG. 1 is a top view of one pixel constituting the liquid crystal display device of the present embodiment. 2 is a cross-sectional view taken along the line AA in FIG. The portion indicated by the reflected light 62 is a reflective display portion, and the other portion indicated by the transmitted light 61 is a transmissive display portion. 1 and 2, the liquid crystal display device according to the present invention is exemplified as an IPS type transflective liquid crystal display device. However, in light of the gist of the present invention, the present invention is also applied to a transflective liquid crystal display device other than the IPS type. The invention can be applied.

  The liquid crystal display device mainly includes a first substrate 31, a second substrate 32, and the liquid crystal layer 10 sandwiched between the first substrate 31 and the second substrate 32.

  The first substrate 31 includes a color filter 36, a planarizing layer 37, a built-in retardation plate 38, a step forming resist layer 39, and a first alignment film 33 on the liquid crystal layer 10 side in the reflective display portion. And have. The first substrate 31 has a color filter 36, a planarizing layer 37, a residual layer 38 n, and a first alignment film 33 on the liquid crystal layer 10 side in the transmissive display portion. Since the color filter 36 is formed on the main surface of the first substrate 31, the first substrate 31 is also referred to as a color filter substrate including the above-described structure formed on the main surface (opposing the liquid crystal layer 10).

  The first substrate 31 is made of borosilicate glass with few ionic impurities and has a thickness of about 0.5 mm.

  The color filter 36 is configured by repeatedly arranging a black matrix and colored resist layers of red (R), green (G), and blue (B) in a stripe shape. Each stripe is parallel to the signal wiring 22. The unevenness caused by the colored resist of the color filter 36 is flattened by a resin flattening layer 37. Unevenness occurs in the main surface of the first substrate 31 on which a plurality of colored resists constituting the color filter 36 and the colored resist and a light shielding layer separating them are formed. The “planarization of the color filter 36” to be described later is to cover the plurality of colored resists and these and the light shielding layer with an insulating material such as a resin so that the undulations on the upper surface of the insulating film 37 are the color filter 36 as the underlying film. That is, it is less than the undulation on the upper surface of the insulating film, and the process of leaving a slight undulation on the upper surface of the insulating film (flattening film) 37 is not excluded.

  The planarizing layer 37 is preferably a transparent material, and the thickness thereof is usually in the range of 0.5 μm to 3 μm from the viewpoint of sufficiently planarizing the colored resist layer. The portion 37 of the flattening layer 37 that contacts the built-in retardation plate 38 has a structure that can orient the built-in retardation plate 38 (hereinafter also referred to as “alignment regulating structure”). That is, there are a plurality of grooves formed with minute irregularities. In the orientation regulating structure, for example, a plurality of linear grooves each extending in the first direction are crossed in the first direction on the upper surface of the planarizing layer 37 (the main surface on which the built-in retardation plate 38 is formed). Formed side by side in the second direction.

  The built-in retardation plate 38 is a layer obtained by curing a liquid crystal material having a birefringence. The built-in retardation plate 38 is oriented by the orientation regulating structure of the planarizing layer 37 that is in contact therewith.

  The residual layer 38n is a portion where the material applied over the entire surface in order to form the built-in retardation plate 38 in the manufacturing process is cured without having the retardation.

  The step forming resist layer 39 is provided to form a quarter-wave retardation difference between the reflective display portion and the transmissive display portion. The step-forming resist layer 39 shown in FIG. 2 is formed on the main surface of the first substrate 31 and propagates light incident on the first substrate 31 from the outside of the liquid crystal display device to the liquid crystal layer 10. However, the step-forming resist layer 39 and its equivalent may be formed as an opaque layer on the main surface of the second substrate 32.

  The first alignment film 33 is a polyimide-based organic film and is subjected to an alignment process by a rubbing method, and aligns the adjacent liquid crystal layer 10 in the alignment process direction.

  A layer for flattening the built-in retardation plate 38 and the residual layer 38n may be further provided, for example, between these and the first alignment film 33.

  The second substrate 32 has a thin film transistor (TFT) on the liquid crystal layer 10 side. The thin film transistor is connected to the scanning wiring 21, the signal wiring 22, and the pixel electrode 28. The thin film transistor has an inverted staggered structure, and its channel portion is formed of an amorphous silicon layer 25 (amorphous silicon layer). The amorphous silicon layer 25 may be annealed with a laser and changed to a channel portion of polycrystalline silicon or continuous grain silicon (Continuous Grain Silicon). At this time, in the thin film transistor, the control electrode (scanning wiring 21, gate electrode) for applying an electric field to the channel portion is disposed above the channel portion, rather than the inverted stagger type structure in which the control electrode is disposed below the channel portion. It may be a positive staggered structure. In addition to this, the second substrate 32 includes a common wiring 23 and a common electrode 29. The scanning wiring 21 and the signal wiring 22 intersect each other. Although not shown in FIGS. 1 and 2, a plurality of pixel electrodes 28 are two-dimensionally arranged on the main surface (opposing the liquid crystal layer 10) of the second substrate 32 and extend in the first direction. The plurality of scanning lines 21 are arranged in parallel in the second direction intersecting with the first direction, and the plurality of signal lines 22 extending in the second direction are arranged in parallel in the first direction. Separate each from the others. Each thin film transistor is provided between one of the plurality of signal wirings 22 corresponding thereto and the pixel electrode 28 and is controlled by one of the plurality of scanning wirings 21. Located at the intersection with. Since the second substrate 32 has a thin film transistor TFT (a structure surrounded by a broken line frame) formed on the main surface thereof, the above-described structure formed on the main surface (opposite the liquid crystal layer 10) is formed. It is also called a TFT substrate.

  The common wiring 23 extends in the first direction like the scanning wiring 21, but has a structure protruding in the pixel electrode 28 (toward the scanning wiring 21) at a portion intersecting with the pixel electrode 28. As shown by the reflected light 62 in FIG. 2, the light reaching the first substrate 31 through the liquid crystal layer 10 is reflected. 1 and 2, the portion where the common wiring 23 overlaps with the pixel electrode 28 is a reflective display portion, and the other portion where the pixel electrode 28 and common electrode 29 overlap is indicated by transmitted light 61 in FIG. 2. In this manner, the light from the backlight passes through and becomes a transmissive display portion. The common wiring 23 formed with the thin film transistor TFT on the second substrate 32 is peculiar to the IPS liquid crystal display device in which the common electrode 29 is formed on the second substrate 32, and the reflection display including the common wiring 23 is provided. The part is not found in a TN mode or VA mode transflective liquid crystal display device.

  Since the optimal liquid crystal layer thickness differs between the transmissive display portion and the reflective display portion, a step may be provided at the boundary. In order to shorten the boundary between the transmissive display unit and the reflective display unit, the transmissive display unit and the reflective display unit are arranged so that the boundary is parallel to the short side of the pixel.

  If wiring such as the common wiring 23 is also used as a reflector, an effect of reducing the manufacturing process required for each can be obtained. If the common wiring 23 is made of a metal such as aluminum or tantalum having a high reflectance, a brighter reflective display can be obtained. The same effect can be obtained even if the common wiring 23 is made of chromium and a reflector made of aluminum or silver alloy is separately formed.

  The liquid crystal layer 10 is a liquid crystal composition exhibiting positive dielectric anisotropy in which the dielectric constant in the alignment direction is larger than that in the normal direction. Its birefringence is 0.067 at 25 ° C., and it exhibits a nematic phase in a wide temperature range including a room temperature range. In addition, during a holding period when driving at a frequency of 60 Hz using a thin film transistor, a high resistance value that does not cause flicker by sufficiently holding reflectance and transmittance is exhibited.

  As described above, the built-in retardation plate 38 is formed on the planarization layer 37 of the reflective display unit. Conventionally, an alignment film is formed on the planarizing layer 37 and a built-in retardation plate 38 is formed thereon, thereby aligning the built-in retardation plate 38 composed of molecules exhibiting birefringence such as liquid crystal molecules. I had sex. On the other hand, in this embodiment, the alignment film is not formed in order to simplify the manufacturing process. A portion 37 a of the planarizing layer 37 that contacts the built-in retardation plate 38 is given an orientation regulating force, and the built-in retardation plate 38 is formed directly. That is, in the present embodiment, the planarization layer 37 plays the role of orienting the built-in retardation plate 38 in addition to the original role of planarizing the color filter 36.

  Although it is conceivable that the conventional alignment film is formed thick and serves also as a flattening layer, the material of the alignment film is not transparent. Therefore, increasing the thickness for flattening impairs permeability, which is not realistic. Thickening the alignment film that determines the initial orientation of the liquid crystal molecules forming the liquid crystal layer of the liquid crystal display (the region where the light transmittance is controlled by the electric field) (for example, the orientation of the optical axis of the liquid crystal when no electric field is applied) When formed, the following adverse effect is caused, one of which is a significant attenuation of the intensity of light transmitted through the alignment film (for example, visible light in the wavelength band of 380 to 780 nm), that is, the low transmittance of the alignment film is When the thin film is formed, the image display function of the liquid crystal display device is impaired as the thick film is formed. In addition, the alignment film must give the liquid crystal molecules aligned in the initial orientation a movement that changes the orientation of the optical axis according to the electric field applied thereto. Therefore, so Material itself of the orientation film is limited, the price is also high.

On the other hand, the built-in retardation plate 38 of the present invention is composed of molecules exhibiting so-called birefringence such as liquid crystal molecules (liquid crystal polymers), and one of a plurality of optical axes having different refractive indexes (for example, The molecules are oriented by the planarizing layer 37 so that the optical axis exhibiting a high refractive index is oriented in a specific direction. However, it is desirable that the molecules constituting the built-in retardation plate 38 be oriented in the specific direction regardless of the strength of the electric field applied to the liquid crystal layer. For this reason, in the present invention, molecules (optical anisotropic bodies) constituting the built-in retardation plate 38 are aligned by the alignment regulating structure of the planarizing layer 37.
<Manufacturing process of built-in retardation plate>
Here, a characteristic manufacturing process of the present embodiment for forming the planarizing layer 37 and the built-in retardation plate 38 will be described.

  FIG. 3 is a diagram illustrating a process from the formation process of the color filter 36 to the formation process of the first alignment film 33.

  First, a black matrix is formed (S11), and three primary color resist layers are formed (S12). Next, the photocurable resin composition that is the material of the planarizing layer 37 is applied over the entire surface (S13). And after apply | coating the photocurable resin composition apply | coated partially photocuring (S14), it develops in order to remove an uncured part (S15). Subsequently, the material for the built-in retardation plate 38 is applied over the entire surface (S16) and then heated (S17). Thereafter, the entire material of the built-in retardation plate 38 is irradiated with light and cured (S18).

  FIG. 4 is a diagram for explaining the process from the formation process of the planarization layer 37 to the formation process of the built-in retardation plate 38.

  First, a planarizing layer material 37p of a photocurable resin composition is applied to a first substrate 31 on which a color filter 36 (not shown in FIG. 4) is formed. Since this composition (precursor of the flattening layer) contains a solvent or the like, the coating thickness thereof is in the range of 1 to 3 μm after post-baking of the composition (film thickness of the flattening layer) described later. Thus, it is thicker than the film thickness. Then, after pre-baking, as shown in FIG. 4A, a photomask 110 is disposed, and the planarizing layer material 37p is irradiated with ultraviolet rays (for example, 1000 mJ / cm 2) from the light source 120. Thereafter, post-baking of the planarizing layer material 37p is performed at 200 ° C. for 30 minutes.

  The photomask 110 has a plurality of linear mask closing portions in a portion corresponding to a portion where the built-in retardation plate 38 is disposed. On the other hand, the portion corresponding to the transmissive display portion has no mask closing portion, and the light from the light source 120 is transmitted as it is. In the figure, the black portion is a mask closing portion where light is blocked. However, in the drawing, for easy understanding, the line width is increased, and the mask closing portion is illustrated in an enlarged manner as compared with other portions.

  By using such a photomask 110, the exposed portions and the non-exposed portions are alternately arranged linearly in the portion 37a where the built-in retardation plate 38 of the planarizing layer material 37p is disposed. That is, the hardened portion and the unhardened portion are alternately arranged in a line.

  After exposure using the photomask 110, the uncured portion of the planarization layer material 37p is removed by alkali organic development. Then, as shown in FIG. 4B, the planarization layer 37 has a structure in which a plurality of fine slit-like dents are arranged in the reflective display portion (the portion 37a where the built-in retardation plate 38 is disposed). For example, a plurality of fine grooves are formed. In this embodiment, the dent is formed with a depth of 1 μm or less. However, the dent may be formed as a plurality of slits penetrating the planarizing layer 37, and the underlying layer (for example, the color filter 36) of the planarizing layer 37 may be exposed by each of the dents. These fine grooves serve as a base for orienting the built-in retardation plate 38.

  The width of the slit-like dent is preferably 2 to 5 μm in order to give an alignment regulating force to the built-in retardation plate 38. Moreover, it is preferable that the space | interval is 2-5 micrometers. The indentation width L and the interval S may be appropriately selected so as to satisfy the relationship “L = S” or the relationship “L + S ≦ 5 μm”. In addition, it is necessary to determine the pattern of the mask closing portion of the photomask 110 so that dents with appropriate widths can be formed at appropriate intervals. For example, the width of the linear mask closing portion of the photomask 110 is 2 μm, and the interval is 2 μm.

  Here, the material of the planarization layer 37 used in this embodiment will be described. The material of the planarization layer 37 is not particularly limited as long as it can sufficiently planarize the three primary color resist layers of the color filter 36 and can form an alignment regulating structure that can properly align the built-in retardation plate 38. Absent.

  In the present embodiment, as described above, since partial curing is performed by light, the material for the planarization layer 37 is preferably one that undergoes a polymerization reaction with light energy such as ultraviolet rays.

  Examples of such a material for the flattening layer 37 include a composition that is cured by ultraviolet irradiation and heating using, as a main component, an acrylic resin component, a solvent, a photocuring initiator, a thermal polymerization initiator, and the like.

  The acrylic resin component preferably contains a polyfunctional (meth) acrylate having a polymerizable acrylic group or an oligomer thereof in order to impart photocurability, and is advantageously 50% by weight of the acrylic resin component. % Or more is preferable. It is also preferable to contain a trifunctional or higher polyfunctional (meth) acrylate or an oligomer thereof as the polymerizable acrylic resin component, and it is preferable to contain 20% by weight or more of the acrylic resin component.

  Preferable acrylic resin components include polyfunctional (meth) acrylates having a fluorene skeleton or oligomers thereof.

  Examples thereof include compounds having a cardo structure having a fluorene skeleton represented by the following formula (I) or formula (II). By employing a resin component having a fluorene skeleton, the heat resistance of the resin matrix can be increased. The resin component having a fluorene skeleton is preferably contained in an amount of 30% by weight or more of the acrylic resin component. An epoxy acrylate resin of novolac resin can be used instead of the resin component having a fluorene skeleton. The compound represented by the formula (II) can be obtained, for example, by a reaction between an epoxy compound represented by the formula (III) and (meth) acrylic acid. The compound represented by the formula (I) can be obtained, for example, by the reaction of the compound represented by the formula (II) with a dibasic acid or an anhydride of a tetrabasic acid. The range is 0: 100 to 100: 0.

  In the above formulas (I) to (III), R bonded to the benzene ring represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, preferably a hydrogen atom, and R bonded to the acrylic group is a hydrogen atom or methyl. Represents a group, and n and m represent an integer of 0 to 20. Y and Z represent polybasic acid residues. Here, it is preferable that the average of n (average repetition number) is 0-1.

  Of course, other resin components other than the acrylic resin component can be used as long as the effects of the planarizing layer 37 are not impaired. Examples of these other resin components include epoxy resins, phenol resins, and the like, olefin resins, vinyl resins, polyester resins, monomers that provide them, and resin components such as curing agents.

  The planarizing layer 37 is made of a photocurable resin composition containing (A) an alkali-soluble polymer, (B) 1,2-naphthoquinonediazide sulfonic acid ester, and (C) an epoxy compound as shown below. It may be.

Such a photocurable resin composition is, for example, as (A) an alkali-soluble polymer,
Formula (1)

  The structural unit (1) or structural unit (1) represented by the following formula (2)

(Here, R1 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R2 represents a hydrogen atom, a methyl group or a methoxy group)
And an alkali-soluble polymer comprising a polymer comprising 100 to 70 mol% of the structural unit (1) based on the total of the structural unit (1) and the structural unit (2). ,
(B) Following formula (3)

(Here, three D's are the same or different and each represents a 1,2-naphthoquinonediazido-4-sulfonyl group or a 1,2-naphthoquinonediazide-5-sulfonyl group, provided that at least one D is 1 , 2-naphthoquinonediazide-4-sulfonyl group or 1,2-naphthoquinonediazide-5-sulfonyl group)
And a compound represented by the following formula (4)

  A photocurable resin composition comprising a 1,2-naphthoquinone diazide sulfonic acid ester selected from the compounds represented by formula (C), and (C) a compound having at least two epoxy groups in the molecule.

  Further, as the material of the planarizing layer 37, (a) an acrylic polymer having a photopolymerizable unsaturated group, (b) a photopolymerizable unsaturated compound having at least one ethylenically unsaturated group, (c) activity You may use the photocurable resin composition containing the photoinitiator which produces | generates a free radical by light.

  (A) The acrylic polymer having a photopolymerizable unsaturated group is not particularly limited in its composition and synthesis method, and examples thereof include a carboxyl group, a hydroxyl group, an amino group, an isocyanate group, an oxirane ring, and an acid anhydride. A side chain obtained by subjecting a vinyl copolymer having a functional group to an addition reaction of a compound having at least one ethylenically unsaturated group and one functional group such as an oxirane ring, an isocyanate group, a hydroxyl group, or a carboxyl group. In addition, a radically polymerizable copolymer having an ethylenically unsaturated group can be used.

  (B) As the photopolymerizable unsaturated compound having at least one ethylenically unsaturated group, for example, a compound obtained by reacting a polyhydric alcohol with an α, β-unsaturated carboxylic acid, 2,2-bis (4- (di (meth) acryloxypolyethoxy) phenyl) propane, a compound obtained by reacting a glycidyl group-containing compound with an α, β-unsaturated carboxylic acid, a urethane monomer, nonylphenyldioxylene (meth) acrylate, γ-chloro-β-hydroxypropyl-β ′-(meth) acryloyloxyethyl-o-phthalate, β-hydroxyethyl-β ′-(meth) acryloyloxyethyl-o-phthalate, β-hydroxypropyl-β′- (Meth) acryloyloxyethyl-o-phthalate, (meth) acrylic acid alkyl ester and the like. For example, (meth) acrylic acid means acrylic acid and methacrylic acid corresponding thereto, and (meth) acrylate means acrylate and methacrylate corresponding thereto.

  Moreover, as a material of the commercially available flattening layer 37, Nippon Steel Chemical Co., Ltd. V-259PA series, JSR Co., Ltd. optomer PC (positive type photosensitive), the company's NN series (negative type photosensitive type) ), CR-600 manufactured by Hitachi Chemical Co., Ltd. can be used.

  Returning to FIG. 3, the description of the built-in retardation plate will be continued.

  Once the planarizing layer 37 is formed, the material of the built-in retardation plate 38 is applied to the entire surface of the planarizing layer 37 and heated at 100 ° C. for 2 to 5 minutes using a hot plate or the like to remove the solvent. To do. Next, by holding the heating temperature at 80 ° C. for about 10 minutes, the material (molecules) of the built-in retardation plate 38 is oriented in a predetermined direction by the orientation regulating structure 37a of the planarization layer 37 (S17). The material of the built-in retardation plate 38 is, for example, an organic solvent containing a liquid crystal having a photoreactive acrylic group at the molecular end and a reaction initiator. The heating temperature in this step (S17) is higher than the melting point (for example, 70 ° C.) of the material of the built-in retardation plate 38 and is equal to or lower than the nematic / isotropic phase transition temperature (for example, 110 ° C.) of the material. For example, it is set to about 80 ° C. The heating time needs to be set to a time (for example, 10 minutes) in which the phase difference plate material is sufficiently oriented. At this point, the portion of the material of the built-in retardation plate 38 that is in contact with the “portion 37 a having the alignment regulating structure of the planarization layer 37” is oriented in a specific orientation direction. Thereby, the said part of the material layer of the built-in phase difference plate 38 shows birefringence (retardation property). On the other hand, the other part in contact with the “part 37b not provided with the orientation regulating structure of the planarization layer 37” of the material of the internal retardation plate 38 is not oriented. Therefore, the other part of the material layer of the built-in retardation plate 38 does not exhibit birefringence (phase difference).

  Thereafter, the entire surface of the material of the built-in retardation plate 38 is exposed and cured (S18). As a result, as shown in FIG. 4C, a built-in retardation plate 38 having phase difference and a residual layer 38n having no phase difference are formed.

  After the built-in retardation plate 38 is formed, a protective film (insulating film, not shown) is formed on the entire main surface of the first substrate 31 (the built-in retardation plate 38 formed on the main surface and the upper surface of the residual layer 38n). ). The protective film is formed of, for example, the same material as the above-described planarization layer or a transparent material that does not include a photoinitiator. After forming the step forming resist layer 39 on the upper surface of the remaining layer 38n (or the protective film formed thereon) (S19 in FIG. 3), an alignment film 33 for aligning the liquid crystal layer 10 is formed (S20). . Note that, before the alignment film 33 is formed, a planarization layer may be formed to planarize the base, and the alignment film 33 may be formed on the planarization layer.

  The process from the formation process of the color filter 36 to the formation process of the alignment film 33 in the first substrate 31 has been described above.

  The subsequent manufacturing process is described as follows with reference to FIG.

  The first alignment film 33 of the first substrate 31 and the second alignment film 34 of the second substrate 32 are rubbed so as to form 15 degrees with respect to the signal wiring 22, and then the first substrate 31. And the second substrate 32 are opposed to each other, and a liquid crystal material is sealed to form the liquid crystal layer 10. Further, the first polarizing plate 41 and the second polarizing plate 42 are disposed outside the first substrate 31 and the second substrate 32. The transmission axes of the first polarizing plate 41 and the second polarizing plate 42 are arranged so as to be orthogonal and parallel to the liquid crystal alignment direction, respectively.

As the adhesive layer of the first polarizing plate 41, a light diffusable adhesive layer 43 in which a large number of transparent microspheres having a refractive index different from that of the adhesive material is mixed is used. It has the effect of expanding the optical path of incident light by utilizing the effect of refraction caused by the difference in refractive index between the adhesive material and the microsphere. Thereby, iridescent coloring caused by interference of reflected light between the pixel electrode 28 and the common electrode 29 can be reduced.
<Mode 1 of Liquid Crystal Display Device According to the Present Invention>
The function of the liquid crystal display device configured as described above will be described.

  As shown in FIG. 1, a common electrode 29 and a pixel electrode 28 are laminated in this order on the main surface of the second substrate 32 made of a material such as glass transparent to visible light for each pixel. Yes. On the main surface of the second substrate 32, the scanning lines 21 and the common lines 23 extending in the first direction are alternately and repeatedly arranged in the second direction, and the scanning lines 21 and the common lines 23 are arranged. On the insulating layer 51 to be covered, a plurality of signal wirings 22 extending in the second direction are arranged in parallel along the first direction. The main surface of the second substrate 32 is provided with a plurality of thin film transistors TFT corresponding to each of the plurality of pixels. A thin film transistor TFT surrounded by a broken line frame in FIGS. 1 and 2 includes a semiconductor layer (amorphous silicon layer) 25 bonded to a part of the signal wiring 22 and the input / output electrode 24, and the semiconductor layer 25. And an electrode (which is also a part of the scanning wiring 21) for controlling the flow of carriers (electrons and holes) between a part of the signal wiring 22 and the input / output electrode 24 by applying an electric field to It is configured as a field effect transistor. One of the signal wiring 22 and the input / output electrode 24 is called a source electrode and the other is called a drain electrode according to the flow of carriers in the semiconductor layer 25 interposed therebetween. A part of the scanning wiring 21 for applying an electric field to the semiconductor layer 25 through the insulating layer 51 is also called a gate electrode or a control electrode, and the insulating layer 51 is also called a gate insulating film.

  The signal wiring 22 transmits a video signal to be taken into the pixel electrode 28 every predetermined period (for example, a frame period or a field). A signal (scanning signal) that causes a carrier flow in the semiconductor layer 25 is applied to the scanning wiring 21 for each period, and a video signal transmitted through the signal wiring 22 passes through the semiconductor layer 25 and the input / output electrode 24 to be a pixel electrode. 28. The input / output electrode 24 and the pixel electrode 28 of the thin film transistor TFT are formed on the inner wall of the through hole 26 that penetrates the insulating layer 52 and the insulating layer 53 laminated on the input / output electrode 24 and exposes the input / output electrode 24. It is electrically connected by a conductive film. This conductive film may be formed together with the pixel electrode 28. On the other hand, the potential of the common wiring 23 varies less than the scanning wiring 21 and the signal wiring 22, and is often kept at a reference potential (a constant potential, for example, a ground potential). The common wiring 23 and the common electrode 29 are formed of a conductive film formed on the inner wall of the through hole 27 that penetrates the insulating layer 51 and the insulating layer 52 stacked on the common wiring 23 and exposes a part of the common wiring 23. Electrically connected. This conductive film may be formed together with the common electrode 29.

  Both the common electrode 29 and the pixel electrode 28 are made of a conductive material (so-called transparent conductive film) that transmits visible light such as ITO (Indium-Tin-Oxide) or IZO (Indium-Zinc-Oxide). The pixel electrode 28 and the common electrode 29 have a substantially rectangular outline, and the outer periphery of the pixel electrode 28 is surrounded by the outer periphery of the common electrode 29 as shown in the plan view of FIG. An opening (not shown) for avoiding an electrical short circuit with the conductive film formed in the through hole 26 is formed in a part of the common electrode 29 so as to surround the through hole 26.

  In each pixel, the common electrode 29 is formed in a single sheet shape, while the pixel electrode 28 is formed in a comb-teeth shape on the common electrode 29. In the pixel electrode 28 shown in FIG. 1, a plurality of openings (linear openings) 30 extending in a first direction (extending direction of the scanning wiring 21) are formed in a rectangular transparent conductive film in a second direction (signal wiring). 22 extending direction). By these openings 30, the transparent conductive film forming the pixel electrode 28 is divided into a plurality of stripes extending in the first direction, and these stripes are arranged in the second direction like comb teeth.

  The pixel electrode 28 and the common electrode 29 are electrically separated by an insulating layer 53 that separates the pixel electrode 28 and the common electrode 29, and electric lines of force generated by a potential difference between the pixel electrode 28 and the common electrode 29 are “comb teeth” of the pixel electrode 28. ”To the common electrode 29 through the“ comb teeth ”(opening 30 of the transparent conductive film).

  The lines of electric force extend substantially parallel to the main surface of the second substrate 32 toward the gap separating the “comb teeth” from the “comb teeth” of the pixel electrode 28. Electric lines of force substantially parallel to the main surface of the second substrate 32 are enclosed between the TFT substrate 32 and the color filter substrate 31 through the second alignment film 34 formed on the second substrate 32 ( The liquid crystal layer 10 that has been sealed) oozes out and moves the liquid crystal molecules in the liquid crystal layer 10.

  Polarizing plates (films) 42 and 41 are provided on the outer surfaces (outer surface, main surface opposite to the liquid crystal layer) of the TFT substrate 32 and the color filter substrate 31, respectively.

  The liquid crystal molecules in the liquid crystal layer 10 are set in an orientation in which the optical axis is shifted (for example, orthogonal) to the optical axes of the polarizing plates 41 and 42 in a state where an electric field is not applied thereto. The first alignment film 33 and the second alignment film 34 set the liquid crystal molecules in such an orientation. The optical axis here is described as an orientation indicating, for example, a high refractive index with respect to light transmitted through the liquid crystal molecules and the polarizing plates 41 and 42.

  On the other hand, as the electric field formed substantially parallel to the main surface of the second substrate 32 from the “comb” of the pixel electrode toward the common electrode 29 increases, the orientation of each optical axis of the liquid crystal molecules becomes It gradually approaches that of the optical axis of the polarizing plates 41 and. That is, as the electric field formed in the second substrate 32 (ln-plane) increases, the amount of light transmitted through the liquid crystal layer increases. This is why the illustrated pixel structure is referred to as an in-plane switching type, or IPS type for short.

  While the potential of the pixel electrode 28 changes according to the output (image information) from the thin film transistor, the potential of the common electrode 29 is determined according to the reference voltage applied from the common wiring 23. That is, in a group of images each having a common electrode 29 connected to a certain common wiring 23, even when the potentials of the respective pixel electrodes are different from each other, the respective common potentials show substantially the same potential.

  The common wiring 23 may be formed of a metal such as aluminum or tantalum so that light incident on the common wiring 23 is more easily reflected than the pixel electrode and the common electrode. The illustrated common line 23 extends from the through hole 27 in contact with the common electrode 29 toward the inside of the pixel. Accordingly, the extended portion of the common wiring 23 is disposed below the pixel electrode 28 and the common electrode 29, and passes through the liquid crystal layer 10, the pixel electrode 28, and the common electrode 29 from the color filter substrate 31. The light incident on the upper surface thereof is reflected toward the color filter substrate 31. A structure in which such a region is formed for each pixel is a feature of a transflective liquid crystal display device.

  The embodiment of the present invention has been described above.

  According to the above embodiment, in the manufacturing process, in the flattening layer formed by coating over the entire surface of the transmissive display portion and the reflective display portion, only in the reflective display portion portion, the alignment regulating force is improved by means of photocuring. Give it. And among the materials of the built-in retardation plate applied over the entire surface, only the portion corresponding to the reflective display portion is oriented to maintain the retardation. That is, the alignment film coating process for aligning the built-in retardation plate 38 and the rubbing process associated therewith can be omitted. Therefore, the time required for manufacturing and material costs can be reduced by reducing the number of processes.

  Further, conventionally, a rubbing cloth or alignment film peeling foreign matter generated during the rubbing treatment is generated, and a cleaning process must be added after that, and even if cleaning is performed, it flows into the subsequent process. Was inevitable and caused a decrease in yield. On the other hand, in the manufacturing process of the present embodiment, there is no rubbing step of the alignment film for aligning the built-in retardation plate 38, so that no rubbing foreign matter is generated and there is no risk of yield reduction.

  Furthermore, in the liquid crystal display device of this embodiment, the transmittance of the transmissive display unit and the reflective display unit is improved by eliminating the alignment film for aligning the built-in retardation plate 38.

  In addition, this invention is not restrict | limited to the said embodiment. The above embodiment can be variously modified.

<Mode 2 of Liquid Crystal Display Device According to the Present Invention>
As a modification of the above-described form 1 of the liquid crystal display device, a VA transflective liquid crystal display device according to the present invention will be described with reference to FIG. FIG. 6A shows a cross-sectional structure of one pixel formed in a VA mode transflective liquid crystal display device, and FIG. 6B shows a planar structure of the one pixel. 6A is drawn as a cross section of the liquid crystal display device (one pixel thereof) cut along the line AA ′ shown in FIG. 6B. Among the components shown in FIG. 6, those equivalents of which are also shown in FIG. 1 or FIG. 2 are given the same reference numerals as the equivalents of FIG. 1 and FIG. One pixel may be defined as a region surrounded by the opening 35 h of the black matrix (light shielding film) 35 or may be defined as a region surrounded by the outline (outer periphery) of the color filter (colored resist) 36. In FIG. 6B, the signal line 22a is formed in the same manner as the signal line 22 except that it is not connected to the thin film transistor TFT of the illustrated pixel. In FIG. 6B, a part of the signal wiring 22 and the input / output electrode 24 are formed on the semiconductor layer 25 whose outline is indicated by a dotted frame so as to face each other. A part of the signal wiring 22 is bent in a U shape and surrounds the input / output electrode 24.

First, a difference between a VA transflective liquid crystal display device and an IPS transflective liquid crystal display device will be described. In the VA liquid crystal display device, the common electrode 29 is formed on the first substrate 31, and an opening 29h of the common electrode 29 is formed in each of the reflective display portion and the transmissive display portion provided for each pixel. Is done. The opening 29 h is formed as a slit or notch depending on the shape of the pixel electrode 28. In FIG. 6A, the liquid crystal molecules 100 to which the electric field between the pixel electrode 28 and the common electrode 29 is applied and the liquid crystal molecules 100n to which this electric field is not applied (in other words, initially aligned) are long. Illustrated as an ellipse. The electric field generated between the pixel electrode 28 and the common electrode 29 is shown as a dashed arrow. The electric field generated between the pixel electrode 28 and the common electrode 29 facing each other through the liquid crystal layer 10 is a direction in which the first and second substrates 31 and 32 are separated by the common electrode opening 29h (hereinafter referred to as a cell gap, FIG. 6 (a) is inclined at a predetermined angle with respect to g _R , g _T ). When no electric field is generated between the pixel electrode 28 and the common electrode 29, the liquid crystal molecule 100n having a uniaxial birefringence has a molecular axis (the major axis of the “ellipse”) aligned with the cell gap. Initially oriented. Such initial alignment of the liquid crystal molecules 100n is called “vertical alignment (VA)”. The liquid crystal layer 10 in which the liquid crystal molecules 100n are initially aligned blocks transmission of light incident thereon. Depending on the electric field strength between the pixel electrode 28 and the common electrode 29, the molecular axis of the vertically aligned liquid crystal molecules 100n is inclined with respect to the cell gap like that of the liquid crystal molecules 100, and the liquid crystal according to the inclination. The amount of light transmitted through the layer 10 increases.

  It is not necessary to form slits, notches or openings in the pixel electrode 28 unlike the common electrode 29. However, the pixel electrode 28 of this embodiment is provided for each common electrode opening 29h as shown in FIG. It is divided into one reflective pixel electrode 28R and two transmissive pixel electrodes 28T. The input / output electrode 24 of the thin film transistor TFT is electrically connected to the reflective pixel electrode 28R through the through hole 26, and the reflective pixel electrode 28R, the transmissive pixel electrode 28T, and the transmissive pixel electrode 28T are connected by a connecting portion 28C. Each is electrically connected. The reflective pixel electrode 28R is formed of a metal film such as aluminum, titanium, or tantalum, or an alloy film containing aluminum, titanium, tantalum, or the like, and the transmissive pixel electrode 28T is formed of ITO (indium-tin-oxide) or IZO. It is formed of a transparent conductive oxide such as (indium-zinc-oxide), ATO (antimony-added tin oxide), AZO (aluminum-added zinc oxide).

  The thin film transistor TFT has a so-called reverse structure in which the semiconductor layer 25 that connects the signal wiring 22 and the input / output electrode 24 is arranged on a part of the scanning wiring (control electrode) 21 via the insulating layer 51, as in the first embodiment. Although it has a staggered structure, the semiconductor layer 25 may be covered with the insulating layer 51 and the control electrode 21 may be disposed on the insulating layer 51. The semiconductor layer 25 is made of amorphous silicon (amorphous silicon), polycrystalline silicon, and a plurality of crystal grains (band-like single crystals) extending from the junction with the signal wiring 22 toward the junction with the input / output electrode 24. Any of continuous grain boundary crystalline silicon formed in parallel may be used, and elements and molecules other than silicon (silicon) can be used as a semiconductor material.

An insulating layer 52, a step-forming resist layer (insulating layer) 39R, and a reflective pixel electrode 28R are laminated in this order on the top surface of the uppermost layer of the thin film transistor TFT (the signal wiring 22 and the input / output electrode 24 in FIG. 6). . The step-forming resist layer 39R is formed on the second substrate 32 (TFT substrate) unlike that of the first embodiment. The step-forming resist layer 39R is formed at a position similar to that of the insulating layer 53 of Form 1 with a thickness more than twice that of each of the insulating layers 51 and 52. That is, the thickness of the step forming resist layer 39R is such that the uppermost surface of the first substrate 31 (the upper surface of the common electrode 29 in FIG. 6) and the uppermost surface of the second substrate 32 (the reflective pixel in FIG. 6). The gap g _R between the upper surface of the electrode 28R and the upper surface of the first substrate 31 (upper surface of the common electrode 29) and the uppermost surface of the second substrate 32 (in FIG. 6, the transmissive pixel electrode 28T). smaller than the gap g _T of the upper surface), preferably it is adjusted to be approximately half of the gap g _R. When the step forming resist layer 39R is formed by photolithography or the like, a wavy pattern (for example, a corrugated pattern) may be formed on the upper surface thereof, and the pattern may be formed on the upper surface of the reflective pixel electrode 28R. The light reflected by the reflective pixel electrode 28R is appropriately diffused in the pixel provided with the reflective pixel electrode 28R by the wave pattern on the upper surface thereof.

  The first substrate 31 is made of a material that transmits light in the visible region (wavelength band of 380 nm to 780 nm) such as glass or plastic (hereinafter referred to as a transparent material). Colored resist) 36 and a light shielding film 35 separating the adjacent pair are formed. Also in the first mode of the liquid crystal display device shown in FIG. 2, the light shielding film 35 is formed between the color filters 36. The color filter 36 is formed of, for example, a resin material (for example, an organic material such as a resist material) including at least one of a pigment, a dye, and a fluorescent material. The light shielding film 35 is formed as an inorganic thin film such as a metal such as chromium (Cr) or an alloy, or a resin thin film (organic thin film) in which particles having high light absorption such as carbon, cobalt oxide, and black pigment are dispersed. The The light shielding film 35 is also described as being opaque because its light transmittance in the visible region is lower than that of the color filter 36.

  Also in the second embodiment, the color filter 36 and the light shielding film 35 disposed therebetween form the flattening layer 37 for leveling the undulations generated on the main surface of the first substrate 31. Further, in a part (37 a) of the planarizing layer 37, the molecules of the raw material (precursor) of the built-in retardation plate 38 supplied to the upper surface of the planarizing layer 37 are oriented in a desired direction, as in the first embodiment. “Orientation regulating force” is given. Accordingly, the built-in retardation plate 38 (an organic film made of oriented molecules) is formed on the upper surface of the portion 37 a to which the orientation regulating force of the planarizing layer 37 is applied, and the portion 37 b to which the orientation regulating force of the planarizing layer 37 is not imparted. Remaining layers 38n (organic films made of unoriented molecules) of the built-in retardation plate are formed on the upper surface, respectively. Unevenness of the upper surface of the built-in retardation plate 38 and the residual layer 38n is suppressed by the planarizing layer 37 serving as a base, and a common electrode 29 having an opening 29h is formed on the upper surface. In the shape observation by an electron microscope, the built-in retardation plate 38 and the residual layer 38n are seen as being formed as one organic thin film, and are recognized to have the same composition. However, since the “birefringence (phase difference)” indicated by the built-in retardation plate 38 cannot be indicated by the residual layer 38n, these can be reliably identified. As shown in FIG. 6B, the built-in retardation plate 38 (thick line frame) is formed in the residual layer 38n as a plurality of islands respectively facing the reflective pixel electrode 28R in the main surface of the first substrate 31. Is distributed.

  The built-in retardation plate 38 and its residual layer 38n can be formed above the common electrode 29 having the opening 29h via the planarization layer 37. Further, the liquid crystal molecules 100 and 100n of the liquid crystal layer 10 are provided on at least one of the uppermost layer (the common electrode 29 in FIG. 6) and the uppermost layer (the pixel electrodes 28R and 28T in FIG. 6) of the first substrate 31. An alignment film (not shown) for orienting may be formed.

<Suitable material for forming built-in retardation plate>
For example, in the step of forming the built-in retardation plate 38, by appropriately selecting the material for forming the built-in retardation plate 38, the wavelength of light applied to the built-in retardation plate 38, and the photopolymerization initiator added thereto, Coloring of the phase difference plate 38 and the residual layer 38n can be suppressed.

  FIG. 5 is a diagram for explaining wavelengths at which coloring of the liquid crystal material forming the built-in retardation plate 38 occurs. Depending on the liquid crystal material for forming the built-in retardation plate 38, coloring occurs when light having a wavelength of less than 300 nm is absorbed. Therefore, it is better not to irradiate light having a wavelength of less than 300 nm.

  Therefore, it is preferable to use a lamp that can emit light of a specific wavelength. For example, a lamp having a high intensity at a wavelength of 300 nm or more and a very low intensity of light having a wavelength of less than 300 nm is used.

  Alternatively, a filter that blocks light having a wavelength of less than 300 nm may be used. For example, a short wavelength cut ultraviolet filter that blocks short wavelength light is used. In addition, it is preferable to use a filter that cuts all the absorption wavelengths of the liquid crystal material forming the built-in retardation plate 38. For example, a Teijin Tetron film G2 made by Teijin DuPont Film can be used.

  Further, in order to irradiate light of 300 nm or more, the material of the built-in retardation plate 38 needs to be cured by irradiation of light having a wavelength of 300 nm or more. Therefore, it is preferable to select a photopolymerization initiator having absorption at 300 to 400 nm. Preferably, the extinction coefficient in the material of the built-in retardation plate 38 (methanol which is a solvent contained therein or a solvent for the photopolymerization initiator) is in a range of 1000 ml / gcm or more at 365 nm and 100 ml / gcm or more at 405 nm. Is an initiator.

  As a material for forming the built-in retardation plate 38, a liquid crystal monomer having a photoreactive acrylic group at the molecular end as shown below can be used.

  The photopolymerization initiator is preferably non-volatile in consideration of heat exposure. For example, Irgacure (R) 907, Irgacure 369, Irgacure 819, Irgacure 127, DAROCUR (R) TPO, Irgacure OXE01, etc. manufactured by Ciba Specialty Chemicals can be selected. In particular, since Irgacure 819 can be prevented from being colored and has low volatility, the exposure amount can be reduced.

  As described above, by appropriately selecting the material of the built-in retardation plate 38, the wavelength of light to be irradiated, and the photopolymerization initiator, the transmittance of the built-in retardation plate 38 and the residual layer 38n can be changed to visible light (visible light). , For example, light having a wavelength in the range of 400 nm to 800 nm) can be in a range of 90% or more, and coloring of these can be suppressed. That is, if the built-in retardation plate 38 and the residual layer 38n transmit 90% or more of light in the visible light region (for example, a wavelength band of 400 nm to 800 nm) incident thereon, the display luminance of the liquid crystal display device is increased. It is kept high enough.

FIG. 1 is a top view of one pixel of a liquid crystal display device. 2 is a cross-sectional view taken along the line AA in FIG. FIG. 3 shows a part of the manufacturing process. FIG. 4 is a diagram for explaining a process of forming the planarizing layer and the built-in retardation plate. FIG. 5 is a diagram showing the relationship between the wavelength of the light source, the absorption wavelength of the polymerization initiator, and the wavelength at which coloring occurs. FIG. 6 is a cross-sectional view and a top view of one pixel in another liquid crystal display device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Liquid crystal layer 21 ... Scanning wiring 22 ... Signal wiring 23 ... Common wiring 25 ... Amorphous silicon layer 26 ... Through hole 27 ... Through hole 28 ... Pixel electrode 29 ... Common electrode 30 ... Slit 31 ... Color filter substrate 31 ... First substrate 32 ... Second substrate 33 ... First alignment film 34 ... Second alignment Film 36 ... Color filter 37 ... Flattening layer 37p ... Flattening layer material 38 ... Built-in retardation plate, 38n ... Residual layer 39 ... Resist layers 41, 42 ... Polarized light Plate 43 ... Adhesive layers 51, 52, 53 ... Insulating layer 61 ... Transmitted light 62 ... Reflected light

Claims (5)

In the manufacturing method of a transflective liquid crystal display device which is sealed a liquid crystal layer, and a transmissive display section and the reflective display portion between the main surface retarder of the first substrate is built and the second substrate There,
A base layer application step of applying a photocurable resin composition to be a base layer of the retardation plate to the main surface of the first substrate;
Perform partial curing treatment by Ri said coated photocurable resin composition mask exposure, after those curing process, followed by development to remove the uncured portion of the person the photocurable resin composition, before the serial cured photocurable resin composition, and the underlying layer curing step of forming a flat area having no space and the relief having irregularities by the removal of the uncured portions,
The has been the material of the retardation plate in the region and the flat region having the irregularities on the photocurable resin composition was heat-cured was coated cured, before Symbol irregularities were formed region, the orientation of the uneven A phase difference plate forming step of forming a phase difference plate oriented by a regulating force and forming a residual layer not oriented in the flat region ;
An alignment film forming step of forming an alignment film for aligning the liquid crystal layer on the retardation plate and the residual layer;
A method for manufacturing a transflective liquid crystal display device, wherein the steps are performed in this order. And in the underlying layer curing step, the region for forming the irregularities, exposed portion and the unexposed portion have row the mask exposure so as to be arranged alternately in a linear, as the unevenness, a plurality of grooves aligned formation The method of manufacturing a transflective liquid crystal display device according to claim 1 . Claim 1 In the retardation plate forming step, characterized in that the heating before SL above the melting point of the phase difference plate material, and the phase difference plate of a lower temperature than the nematic-isotropic phase transition temperature of the material A method for manufacturing a transflective liquid crystal display device according to claim 2.   4. The method of manufacturing a transflective liquid crystal display device according to claim 1, wherein the first substrate includes a color filter, and the underlayer is formed on the color filter. .   5. The transflective liquid crystal according to claim 1, wherein the uneven region is formed in the reflective display portion, and the flat region is formed in the transmissive display portion. Manufacturing method of display device.

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