Method for manufacturing liquid crystal display device, liquid crystal display device, and exposure device

Abstract

The invention provides a method for manufacturing a liquid crystal display device, a liquid crystal display device and an exposure device, which can suppress the occurrence of display unevenness caused by repeated exposure through a relatively simple method. A method for manufacturing a liquid crystal display device includes an exposure step of exposing an organic film with a photomask interposed therebetween: performing primary exposure on a portion of the organic film, and performing repeated exposure on the remaining at least a portion of the organic film. The photomask (40) has a slit (61a) and a light-shielding section (62a) in a non-overlapping region (45) corresponding to a primary exposure, and has a slit (61b) and a light-shielding section (62b) in an overlapping region (46) corresponding to an overlapping exposure. The opening area of at least a part of the slits (61b) is smaller than the opening area of the slits (61a). The slits (61b) are first slits that are 75% or more and 100% or less of the opening area of the slits (61a), or second slits that are more than 0% and 25% or less of the opening area of the slits (61a).

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a liquid crystal display device, a liquid crystal display device and an exposure device. Background Art

[0002] In liquid crystal displays, especially liquid crystal display panels for large televisions, viewing angle, transmittance, response time, etc. are important performance indicators. As liquid crystal display modes for making the values ​​of these performance indicators good, various modes such as 4Domain-Reverse Twisted Nematic (4D-RTN) mode, 4Domain-Electrically Controlled Birefringence (4D-ECB) mode, Polymer Sustained Alignment (PSA) mode, In Plane Switching (IPS) mode, and Fringe Field Switching (FFS) mode have been developed. In addition, large televisions using these liquid crystal display mode technologies are currently being mass-produced.

[0003] A liquid crystal alignment film for controlling the orientation of liquid crystal molecules in a liquid crystal unit is provided in a liquid crystal display device. As methods for obtaining a liquid crystal alignment film, there are known methods: a method of rubbing an organic film, a method of obliquely evaporating silicon oxide, a method of forming a monomolecular film having a long-chain alkyl group, a method of irradiating a photosensitive organic film with light (photo-orientation method), etc. Among these, the photo-orientation method can impart uniform liquid crystal orientation capability to a photosensitive organic film while suppressing the generation of static electricity or dust, and can also achieve precise control of the orientation direction of liquid crystal molecules, and various studies are being promoted. In the case of imparting liquid crystal orientation capability to a photosensitive organic film by a photo-orientation method, light is usually irradiated to the organic film through a photomask.

[0004] In the manufacturing process of a liquid crystal display device, productivity is improved by taking multiple substrates of a size corresponding to one liquid crystal display device from a mother substrate. However, in the case of manufacturing a large-scale (for example, a 60-inch or 70-inch-level) liquid crystal display device by a photo-alignment method, it is not realistic to irradiate light at one time for a large substrate that can take multiple substrates corresponding to the large screen size. In addition, the enlargement of the photomask leads to an increase in manufacturing costs. Furthermore, in the case of manufacturing a relatively small-scale (for example, a 20-inch or 30-inch-level) liquid crystal display device, in order to achieve a reduction in manufacturing costs, the need to increase the miniaturization of the exposure device is also considered.

[0005] Therefore, when manufacturing a liquid crystal display device by a photo-alignment method, research is being conducted to divide the exposure area on the substrate into a plurality of areas, and to arrange a plurality of photomasks of sizes corresponding to the exposure areas for exposure. However, when the exposure area is divided into a plurality of areas for exposure, the seams between the exposure areas may appear on the screen as display unevenness.

[0006] In order to solve the problem of uneven display such as the above, it has been proposed in the past that the seams between the exposure areas are not easily visually recognized on the display screen by improving the photomask pattern (for example, refer to Patent Document 1). Patent Document 1 discloses dividing the substrate surface into two or more exposure areas, and when exposing an organic film to each exposure area through a photomask, exposing in a manner that repeats a portion of the adjacent exposure areas, and using a photomask having a halftone portion in the area corresponding to the repeated exposure area. The photomask of Patent Document 1 has a plurality of slits in the halftone portion, and the aperture ratio of these plurality of slits decreases continuously in the direction toward the end of the mask. In addition, Patent Document 1 discloses controlling the total irradiation amount of the repeatedly exposed area, thereby making the seams between the exposure areas not easily visually recognized.

[0007] [Prior art literature]

[0008] [Patent Document]

[0009] [Patent Document 1] International Publication No. 2007 / 086474 Summary of the invention

[0010] [Problems to be solved by the invention]

[0011] The inventors and others conducted research and found that, according to the method described in Patent Document 1, although the brightness at the joints between the exposure areas can be suppressed from rising sharply, there is a case where the joints become locally brighter. In addition, in the method of controlling the total irradiation amount of the repeatedly exposed areas so as to make it difficult to visually recognize the joints between the exposure areas, whenever various conditions such as the material of the liquid crystal alignment film or the illumination of the light source change, it is necessary to optimize the photomask pattern according to the total irradiation amount of the repeatedly exposed areas, and there is a concern that the method of suppressing display unevenness becomes complicated.

[0012] The present invention has been made in view of the above-mentioned problems, and its main object is to provide a method for manufacturing a liquid crystal display device, which can suppress the occurrence of display unevenness caused by repeated exposure by a relatively simple method.

[0013] [Technical means to solve the problem]

[0014] In order to solve the above-mentioned problems, the present invention adopts the following means.

[0015] [1] A method for manufacturing a liquid crystal display device, wherein the liquid crystal display device comprises: a substrate, a photo-alignment film formed on the substrate, and a liquid crystal layer adjacent to the photo-alignment film, the method for manufacturing the liquid crystal display device comprising an exposure step, wherein the exposure step causes the substrate on which a photosensitive organic film is formed to move relative to a light source in a predetermined moving direction while exposing the organic film through a photomask, wherein the exposure step exposes a portion of the organic film once and repeatedly exposes at least a portion of the remaining region, wherein the photomask has an opening area in a non-overlapping region corresponding to the portion of the organic film to be exposed once A plurality of identical light-transmitting portions and a light-shielding portion arranged between each light-transmitting portion, a plurality of light-transmitting portions having different opening areas in an overlapping region corresponding to a portion of the organic film to be repeatedly exposed, and a light-shielding portion arranged between each light-transmitting portion, the opening area of ​​at least a part of the plurality of light-transmitting portions arranged in the overlapping region is smaller than the opening area of ​​the light-transmitting portions arranged in the non-overlapping region, each light-transmitting portion arranged in the overlapping region is a first light-transmitting portion having an opening area greater than 75% and less than 100% of the opening area of ​​each light-transmitting portion arranged in the non-overlapping region, or is a second light-transmitting portion having an opening area greater than 0% and less than 25%.

[0016] [2] A method for manufacturing a liquid crystal display device according to [1], wherein the photomask includes a first photomask and a second photomask arranged adjacent to each other along a direction intersecting the moving direction and along the substrate surface, i.e., the intersecting direction, the first photomask and the second photomask are configured so that parts of each other overlap when viewed in the moving direction, the non-overlapping area is an area where the first photomask and the second photomask do not overlap when viewed in the moving direction, and the overlapping area is an area where the first photomask and the second photomask overlap when viewed in the moving direction.

[0017] [3] A method for manufacturing a liquid crystal display device according to [2], wherein the first light-transmitting portion in the overlapping area of ​​one of the first photomask and the second photomask and the second light-transmitting portion or the light-shielding portion in the overlapping area of ​​the other photomask are arranged on the same line extending in the moving direction.

[0018] [4] A method for manufacturing a liquid crystal display device according to [2] or [3], wherein, in the overlapping area, the light-transmitting portion is arranged in such a manner that the sum of the opening areas of the light-transmitting portion contained in an area of ​​a specified length along the crossing direction shows an increasing tendency from the end of the photomask toward the non-overlapping area.

[0019] [5] The method for manufacturing a liquid crystal display device according to any one of [1] to [4], wherein in the overlapping region, the first light-transmitting portion is densely arranged from an end portion of the photomask toward the non-overlapping region.

[0020] [6] A method for manufacturing a liquid crystal display device according to any one of [1] to [5], wherein the overlapping area has a first interval adjacent to the non-overlapping area, and a second interval including an end portion of a photomask, the first light-transmitting portion is arranged in the first interval, and the second light-transmitting portion is not arranged, and the second light-transmitting portion is arranged in the second interval, and the first light-transmitting portion is not arranged.

[0021] [7] A method for manufacturing a liquid crystal display device according to [6], wherein a plurality of the first light-transmitting portions are arranged in the first interval, and an opening area of ​​each of the first light-transmitting portions arranged in the first interval becomes smaller in a direction away from the non-overlapping area.

[0022] [8] A method for manufacturing a liquid crystal display device according to [6] or [7], wherein a plurality of the second light-transmitting portions are arranged in the second interval, and an opening area of ​​each second light-transmitting portion arranged in the second interval becomes smaller in a direction toward an end portion of the photomask.

[0023] [9] A method for manufacturing a liquid crystal display device according to any one of [6] to [8], wherein the overlapping area also has a third interval arranged between the first interval and the second interval, and in the third interval, the first light-transmitting portion is tightly arranged from the second interval toward the first interval.

[0024]

[10] A method for manufacturing a liquid crystal display device according to [9], wherein the opening area of ​​each first light-transmitting portion arranged in the first interval becomes smaller in a direction away from the non-overlapping area, and the opening area of ​​each second light-transmitting portion arranged in the second interval becomes smaller in a direction toward an end portion of the photomask.

[0025]

[11] A method for manufacturing a liquid crystal display device according to any one of [1] to

[10] , wherein, in the overlapping area, the second light-transmitting portion or the light-shielding portion is arranged at a position symmetrical to the first light-transmitting portion with a center line of the overlapping area extending in the moving direction as an axis, and the first light-transmitting portion is arranged at a position symmetrical to the second light-transmitting portion.

[0026]

[12] A method for manufacturing a liquid crystal display device according to any one of [1] to

[11] , wherein the liquid crystal display device has two or more regions in which the orientation directions of liquid crystal molecules in the liquid crystal layer are different within one pixel.

[0027]

[13] The method for manufacturing a liquid crystal display device according to any one of [1] to

[12] , wherein, in the exposure step, polarized ultraviolet rays are irradiated from a direction inclined relative to a substrate surface.

[0028]

[14] The method for manufacturing a liquid crystal display device according to any one of [1] to

[13] , wherein the liquid crystal layer contains liquid crystal molecules having negative dielectric anisotropy.

[0029]

[15] A liquid crystal display device manufactured by the manufacturing method according to any one of [1] to

[14] .

[0030]

[16] An exposure device for manufacturing a photo-alignment film, the exposure device comprising: a light source; a plurality of photomasks; and a scanning unit, wherein a substrate having a photosensitive organic film is moved relative to the light source in a specified moving direction while exposing the organic film through the plurality of photomasks, the plurality of photomasks being arranged in a direction intersecting the moving direction and along a substrate surface, i.e., in the intersecting direction, and comprising a first photomask and a second photomask adjacent to the first photomask, the first photomask and the second photomask being arranged so that parts of each other overlap when viewed in the moving direction, and the first photomask and the second photomask being arranged so that parts of each other overlap when viewed in the moving direction, and the first photomask and the second photomask being arranged so that parts of each other overlap when viewed in the moving direction, respectively. The overlapping non-overlapping regions include a plurality of light-transmitting portions with the same opening area and a light-shielding portion arranged between the light-transmitting portions; the overlapping regions where the first photomask and the second photomask overlap when observed in the moving direction include a plurality of light-transmitting portions with different opening areas and a light-shielding portion arranged between the light-transmitting portions; the opening area of ​​at least a portion of the plurality of light-transmitting portions arranged in the overlapping regions is smaller than the opening area of ​​the light-transmitting portions arranged in the non-overlapping regions; each light-transmitting portion arranged in the overlapping regions is a first light-transmitting portion having an opening area greater than 75% and less than 100% of the opening area of ​​each light-transmitting portion arranged in the non-overlapping regions, or is a second light-transmitting portion having an opening area greater than 0% and less than 25%.

[0031] [Effects of the Invention]

[0032] According to the present invention, a relatively simple method of designing a photomask pattern by combining a first light-transmitting portion and a second light-transmitting portion with opening areas within a specified range in an overlapping region corresponding to a portion where repeated exposure is performed can suppress display unevenness in a liquid crystal display device caused by repeated exposure. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic cross-sectional view showing a schematic structure of a liquid crystal display device.

[0034] Figure 2 is a schematic plan view of the first substrate.

[0035] Figure 3 It is a diagram showing the direction of light irradiation onto the organic film on the first substrate.

[0036] Figure 4 It is a diagram showing the direction of light irradiation onto the organic film on the second substrate.

[0037] Figure 5 The diagram shows the direction of light irradiation to the organic film on the first substrate and the organic film on the second substrate, and the alignment directions of liquid crystal molecules in the liquid crystal layer.

[0038] Figure 6 This is a schematic diagram of an exposure device and scanning exposure.

[0039] Figure 7 It is a diagram showing the arrangement of a photomask.

[0040] Figure 8 This is an enlarged view showing a schematic structure of an overlapping region of the photomask in the first embodiment.

[0041] Fig. 9 It is a figure which shows the result of the brightness evaluation of the liquid crystal cell based on repeated exposure.

[0042] Fig.10 This is an enlarged view showing a schematic structure of an overlapping region in another example of the first embodiment.

[0043] Fig.11 This is an enlarged view schematically showing the structure of the overlapping region of the photomask in the second embodiment.

[0044] Fig.12 This is an enlarged view showing a schematic structure of an overlapping region in another example of the second embodiment.

[0045] Fig.13 It is an enlarged view showing a schematic structure of an overlapping region of a photomask in the third embodiment.

[0046] Fig.14 This is an enlarged view showing a schematic structure of an overlapping region in another example of the third embodiment.

[0047] Fig.15 It is an enlarged view showing a schematic structure of an overlapping region of a photomask in the fourth embodiment.

[0048] Fig.16 This is an enlarged view schematically showing the structure of an overlapping region of a conventional photomask.

[0049] Fig.17 This is an enlarged view schematically showing the structure of an overlapping region of a conventional photomask.

[0050] [Explanation of Symbols]

[0051] 10: Liquid crystal display device

[0052] 29: Organic film

[0053] 29a: Non-overlapping area

[0054] 29b: Overlapping area

[0055] 30: Pixels

[0056] 36: Light Source

[0057] 38: Substrate

[0058] 40: Photomask

[0059] 41: First photomask

[0060] 42: Second photomask

[0061] 43: Joint

[0062] 44: Mask end

[0063] 45: Non-repeating area

[0064] 46: Repeating Region

[0065] 50: Exposure device

[0066] 61, 61a, 61b: slits (light-transmitting parts)

[0067] 62, 62a, 62b: light shielding part

[0068] 63: First slit (first light-transmitting portion)

[0069] 64: Second slit (second light-transmitting portion)

[0070] F1: First section

[0071] F2: Second interval

[0072] F3: The third section

[0073] V: Cross direction

[0074] W: Scan direction DETAILED DESCRIPTION

[0075] Hereinafter, the embodiments will be described with reference to the accompanying drawings. In addition, in each of the following embodiments, the same or equivalent parts are annotated with the same symbols in the drawings, and the description of the parts with the same symbols is cited. In the following description, for convenience, up and down and left and right are shown based on the direction when the display area of ​​the liquid crystal display device is viewed from the front.

[0076] In this specification, the so-called "pixel" refers to the smallest unit that expresses the shades (grayscale) of each color in the display. For example, in a display element of a color filter method, it is equivalent to the unit that expresses each grayscale such as red (R), green (G) and blue (B). Therefore, when expressed as a "pixel", it refers to each pixel (sub-pixel) of R pixels, G pixels and B pixels, rather than a color display pixel (pixel) that combines R pixels, G pixels and B pixels. That is, in the case of a color liquid crystal display element, one pixel corresponds to any color of the color filter. The so-called "pretilt angle" refers to the angle between the surface of the alignment film and the long axis direction of the liquid crystal molecules near the alignment film when no voltage is applied to the liquid crystal layer.

[0077] The so-called "azimuth" refers to the direction on the substrate surface or a plane parallel to the substrate surface. Among them, the azimuth does not take into account the inclination angle of the substrate surface relative to the normal direction. In the absence of special instructions for the reference, the azimuth represented by 0 degrees to 360 degrees is based on the azimuth in the right direction of the horizontal direction of the display surface (i.e., the left and right direction of the display surface, also referred to as the "pixel horizontal direction") as the reference azimuth (0 degrees), and the counterclockwise direction is set as a positive angle.

[0078] The so-called "orientation of liquid crystal molecules in the liquid crystal layer" refers to the direction of the liquid crystal molecules existing near the center in the thickness direction of the liquid crystal layer (more specifically, the liquid crystal molecules existing near the center of the layer in the liquid crystal layer of each pixel and near the center in the thickness direction of the liquid crystal layer), starting from the long axis end of the substrate (first substrate) side where the pixel electrode is arranged and ending at the long axis end of the other substrate (second substrate) side. Therefore, the so-called "orientation obtained by projecting the long axis direction of the liquid crystal molecules existing near the center in the thickness direction of the liquid crystal layer onto the first substrate" refers to the direction of the liquid crystal molecules existing near the center in the thickness direction of the liquid crystal layer, starting from the long axis end of the first substrate side and ending at the long axis end of the second substrate side, projected onto the first substrate.

[0079] The so-called "tilt orientation of liquid crystal molecules" refers to the orientation of liquid crystal molecules existing near the orientation film and controlled by the liquid crystal orientation film when no voltage is applied. In this specification, the tilt orientation of liquid crystal molecules is represented by the orientation starting from the long axis end of the first substrate side and ending at the long axis end of the second substrate side. In this specification, when the visual direction is not particularly indicated, the orientation when the first substrate side is viewed from the front of the second substrate side is represented.

[0080] 《First Implementation Mode》

[0081] First, the structure of the liquid crystal display device 10 manufactured by the manufacturing method of the present disclosure will be described below with reference to the drawings.

[0082] <Liquid crystal display device>

[0083] The liquid crystal display device 10 is a thin film transistor (TFT) type liquid crystal display device, and a plurality of pixels are arranged in a matrix in a display area. Figure 1 As shown in the figure, the liquid crystal display device 10 includes: a pair of substrates, including a first substrate 11 and a second substrate 12; and a liquid crystal layer 13, which is arranged between the first substrate 11 and the second substrate 12. In addition, in this embodiment, the case of being applied to a TFT type liquid crystal display device is described, but the present disclosure can also be applied to other driving methods (for example, a passive matrix method, a plasma address method, etc.).

[0084] The first substrate 11 is a TFT substrate as follows (see Figure 2 ): Pixel electrodes 15 including transparent conductors such as indium tin oxide (Indium Tin Oxide, ITO), TFTs 26 as switching elements, various wirings such as scanning signal lines 17 or data signal lines 18 are arranged on a transparent substrate 14 including glass or resin. The second substrate 12 is a facing substrate as follows: a facing electrode 19 including a transparent conductor is provided on a transparent substrate 16 including glass or resin. The facing electrode 19 is a common electrode shared by all pixel electrodes 15. The second substrate 12 is a color filter (ColorFilter, CF) substrate including a black matrix and a color filter. The color filter has coloring layers of three colors, for example, red (R), green (G) and blue (B). In addition, instead of the structure in which the color filter is provided on the facing substrate, a color filter on array (Color filter on array, COA) provided on the pixel substrate may be used.

[0085] Liquid crystal alignment films are formed on the first substrate 11 and the second substrate 12, respectively, to orient liquid crystal molecules near the substrate surface in a predetermined orientation relative to the substrate surface (i.e., the electrode configuration surface). The liquid crystal alignment film is a vertical alignment film that orients the liquid crystal molecules approximately vertically when no voltage is applied, and the angle (pretilt angle) formed between the alignment film surface and the long axis direction of the liquid crystal molecules near the alignment film is, for example, 85° to 89.9°. The liquid crystal display device 10 has a first alignment film 22 formed on the electrode configuration surface of the first substrate 11, and a second alignment film 23 formed on the electrode configuration surface of the second substrate 12 as liquid crystal alignment films.

[0086] At least one of the first alignment film 22 and the second alignment film 23 is a photo-alignment film. In this embodiment, both the first alignment film 22 and the second alignment film 23 are photo-alignment films. The photo-alignment film is formed by performing a photo-alignment treatment on a photosensitive organic film formed on a substrate using a liquid crystal alignment agent. The liquid crystal display device 10 of this embodiment is orientation-divided, and has two or more regions with different orientation directions in the pixel 30. As a result, the viewing angle characteristics of the liquid crystal display device 10 are compensated.

[0087] As a liquid crystal alignment agent for forming a photo-alignment film, a polymer composition containing a polymer having a photo-alignment structure can be preferably used. As a polymer having a photo-alignment structure, there is no particular limitation, and known components can be suitably used as polymer components of the photo-alignment film. As specific examples of photo-alignment structures, cinnamic acid structure, azobenzene structure, coumarin structure, chalcone structure and cyclobutane structure can be cited. As the main chain of a polymer having a photo-alignment structure, for example, polyamic acid, polyimide, polyorganosiloxane, polyamic acid ester, polyamide, polyenamine, (meth) acrylic polymer, styrene polymer, maleimide polymer, styrene-maleimide polymer, etc. In addition, "(meth) acrylic acid" is a term including "acrylic acid" and "methacrylic acid".

[0088] In addition, the liquid crystal alignment agent used to form the first alignment film 22 and the second alignment film 23 may contain only one polymer as a polymer component, or may contain two or more polymers as polymer components. The liquid crystal alignment agent is generally a liquid composition in which the polymer component is dissolved or dispersed in one or more solvents. In addition to the polymer component, the liquid crystal alignment agent may also contain one or more additives such as a crosslinking agent, a close contact aid, an ultraviolet absorber, and a photosensitizer.

[0089] The first substrate 11 and the second substrate 12 are arranged so that the electrode arrangement surface of the first substrate 11 faces the electrode arrangement surface of the second substrate 12 with a spacer 24 interposed therebetween and a predetermined gap (cell gap) provided. Figure 1, the spacer 24 is a columnar spacer, but it may be a spacer for a liquid crystal display device such as a bead spacer. The first substrate 11 and the second substrate 12 arranged opposite to each other are bonded together with a sealing member 25 interposed therebetween at their peripheries. A liquid crystal composition is filled in a space surrounded by the first substrate 11, the second substrate 12 and the sealing member 25, thereby forming a liquid crystal layer 13 between the first substrate 11 and the second substrate 12. The liquid crystal layer 13 contains liquid crystal having negative dielectric constant anisotropy.

[0090] As the liquid crystal, a known liquid crystal material having negative dielectric constant anisotropy can be used. The refractive index anisotropy Δn of the liquid crystal can be appropriately set so that the retardation (d·Δn) represented by the product of the refractive index anisotropy Δn of the liquid crystal and the thickness d of the liquid crystal layer 13 becomes a desired value. The refractive index anisotropy Δn of the liquid crystal is, for example, 0.06 to 0.14. The thickness d of the liquid crystal layer 13 is, for example, 2 μm to 5 μm.

[0091] A pair of polarizing plates are arranged outside the first substrate 11 and the second substrate 12. The pair of polarizing plates includes a first polarizing plate 27 arranged on the outer surface of the first substrate 11, and a second polarizing plate 28 arranged on the outer surface of the second substrate 12. In the liquid crystal display device 10, the first polarizing plate 27 and the second polarizing plate 28 are arranged in a manner that the polarization axes of each other intersect (more specifically, are orthogonal). A terminal area (not shown) is provided at the outer edge of the first substrate 11, and the liquid crystal display device 10 is driven by connecting a driver integrated circuit (IC) for driving the liquid crystal to the terminal area.

[0092] In addition, in this embodiment, a vertical alignment type liquid crystal display device is described, but the present disclosure can also be applied to a horizontal alignment type liquid crystal display device. In the case of applying to a horizontal alignment type liquid crystal display device, as long as liquid crystal molecules having positive dielectric constant anisotropy are used as liquid crystal molecules of the liquid crystal layer 13, a horizontal alignment type liquid crystal alignment film can be used instead of a vertical alignment film as the liquid crystal alignment film.

[0093] (Pixel structure)

[0094] Next, use Figure 3 to Figure 5 The pixel structure and alignment division of the liquid crystal display device 10 will be described. Figure 3 to Figure 5 Arrows P1 to P4 in FIG. 5 represent the irradiation direction of light to the photosensitive organic film 29 formed of a liquid crystal aligning agent. Figure 5 In FIG. 1 , the cones denoted by symbol 35 represent liquid crystal molecules. Figure 5In the embodiment, the orientation of the liquid crystal molecules in the liquid crystal layer 13 is represented by the orientation of the cone 35. Here, the direction from the bottom surface toward the vertex of the cone 35 is defined as the direction toward the first substrate 11. In the following description, the direction along the short side of the pixel 30 is defined as the X-axis direction, and the direction along the long side of the pixel 30 is defined as the Y-axis direction when looking down at the first substrate 11. In the present embodiment, the X-axis direction is the direction along the lateral direction of the display screen.

[0095] like Figure 3 to Figure 5 As shown in FIG. 1 , each pixel 30 has two square half pixels 30a (i.e., half of a pixel) arranged in the Y-axis direction. The half pixels 30a constituting each pixel 30 have a plurality of alignment regions (hereinafter also referred to as “liquid crystal domains”) in which the alignment directions of the liquid crystal molecules in the liquid crystal layer 13 are different from each other (see FIG. 1 ). Figure 3 to Figure 5 In this embodiment, the organic films 29 formed on the first substrate 11 and the second substrate 12 are exposed multiple times from different directions to form four liquid crystal domains (first domain 31 to fourth domain 34) in the half pixel 30a (see Figure 3 to Figure 5 ).

[0096] Regarding the exposure of each substrate, specifically, for the organic film 29 formed on the first substrate 11, as shown in FIG. Figure 3 As shown in FIG. 1 , in the two regions where the half pixel 30a is divided into two parts in the Y-axis direction, one region is irradiated with light from a direction P1, and the other region is irradiated with light from a direction P2 which is a direction antiparallel to the direction P1. Figure 4 As shown in FIG. 1 , in the two regions in which the half pixel 30a is divided in the X-axis direction, one region is irradiated with light from a direction P3, and the other region is irradiated with light from a direction P4 which is a direction antiparallel to the direction P3. The directions of irradiation of light to the organic film 29 formed on the first substrate 11 and the organic film 29 formed on the second substrate 12 are set to differ by approximately 90° when the first substrate 11 and the second substrate 12 are bonded together (see FIG. 1 ). Figure 5 ). That is, in each liquid crystal domain, the tilt azimuth of the liquid crystal molecules present near the first orientation film 22 and the tilt azimuth of the liquid crystal molecules present near the second orientation film 23 differ from each other by approximately 90°. As a result, the liquid crystal molecules contained in the liquid crystal layer 13 adopt a structure in which they are twisted by approximately 90° between a pair of substrates when a voltage is applied, and adopt a vertical orientation when no voltage is applied. When a voltage is applied, the orientation obtained by projecting the long axis direction of the liquid crystal molecules present near the center in the thickness direction of the liquid crystal layer 13 onto the first substrate 11 is approximately 225°, approximately 135°, approximately 45°, and approximately 315° for the first domain 31 to the fourth domain 34, respectively (refer to Figure 5 ).

[0097] In addition, the structure of the pixel 30 is not limited to Figure 3 to Figure 5 For example, one pixel 30 may be formed by arranging half pixels 30a in the horizontal direction of the display screen. There is no particular limitation on the number of liquid crystal domains in the half pixel 30a, and for example, two may be used. In addition, one pixel is not limited to being divided into eight regions, and one pixel may be divided into four regions, for example. The arrangement of the pixels 30 is not limited to a matrix. The liquid crystal display device 10 has Figure 3 to Figure 5 The pixel 30 shown is divided into eight regions in total, but since the orientation of the liquid crystal molecules is four, it is a four-domain RTN mode or a vertical alignment twisted nematic (VATN) mode. The four-domain RTN mode liquid crystal display device 10 can be obtained by irradiating the organic film 29 formed on the first substrate 11 with light twice and irradiating the organic film 29 formed on the second substrate 12 with light twice, that is, irradiating the light four times in total.

[0098] <Method for manufacturing liquid crystal display device>

[0099] Next, a description will be given of a method for manufacturing the liquid crystal display device 10. The liquid crystal display device 10 can be manufactured by a method including the following film formation step and exposure step.

[0100] Film forming step: a step of applying a liquid crystal aligning agent to a substrate to form a photosensitive organic film (organic film 29)

[0101] Exposure process: a process of exposing the organic film 29 through a photomask while moving the substrate on which the organic film 29 is formed relative to the light source.

[0102] Hereinafter, each step will be described.

[0103] (Film Formation Step)

[0104] First, prepare the first substrate 11 and the second substrate 12. Then, apply the liquid crystal alignment agent on each electrode configuration surface of the first substrate 11 and the second substrate 12 to form a coating film on the substrate. In the film forming step, an organic film 29 is formed on at least one of the first substrate 11 and the second substrate 12. In this embodiment, the organic film 29 is formed on both the first substrate 11 and the second substrate 12. Applying the liquid crystal alignment agent to the substrate is preferably performed by offset printing, flexographic printing, spin coating, roll coater or inkjet printing.

[0105] After applying the liquid crystal alignment agent, it is preferred to perform preheating (prebaking) for the purpose of preventing the applied liquid crystal alignment agent from sagging. The prebaking temperature is preferably 30°C to 200°C, and the prebaking time is preferably 0.25 minutes to 10 minutes. Thereafter, calcination (post-baking) is performed for the purpose of removing the solvent, etc. The calcination temperature (post-baking temperature) is preferably 80°C to 300°C, and the post-baking time is preferably 5 minutes to 200 minutes. The film thickness of the formed coating is, for example, 0.001 μm to 1 μm.

[0106] (Exposure process)

[0107] Then, the organic film 29 formed by the film forming step is subjected to a photo-alignment treatment to give the organic film 29 a desired pre-tilt angle. In the case of a vertical alignment film, the pre-tilt angle is, for example, 85° to 89.9°. In the present embodiment, the organic film 29 formed on each substrate surface of the first substrate 11 and the second substrate 12 is irradiated with polarized radiation (linear polarization) (see Figure 6 As the radiation irradiated to the organic film 29, for example, ultraviolet rays including light with a wavelength of 150 nm to 800 nm and visible rays can be used. Preferably, ultraviolet rays including light with a wavelength of 200 nm to 400 nm are used.

[0108] Examples of the light source used include a low-pressure mercury lamp, a high-pressure mercury lamp, a deuterium lamp, a metal halide lamp, an argon resonance lamp, a xenon lamp, and an excimer laser. The radiation dose is preferably 50 J / m 2 ~50,000J / m 2 , more preferably 100 J / m 2 ~2,000J / m 2 The angle between the irradiation direction of the radiation and the substrate surface is, for example, greater than 30° and less than 90°. After light irradiation, the following treatments may be performed: the substrate surface may be cleaned using water, an organic solvent (e.g., methanol, isopropanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, etc.) or a mixture thereof, or the substrate may be heated.

[0109] The photo-alignment treatment is preferably performed by scanning exposure, wherein the organic film 29 is irradiated with radiation while the substrate is moved in a predetermined direction relative to the light source or the light source is moved in a predetermined direction relative to the substrate. In this embodiment, the organic film 29 formed by the film forming step is exposed multiple times to form a plurality of liquid crystal domains having different orientations obtained by projecting the long axis direction of the liquid crystal molecules present near the center in the thickness direction of the liquid crystal layer 13 onto the first substrate 11. For example, in Figure 3 to Figure 5In the pixel shown, one half-pixel region is divided by alignment into four regions in which the alignment directions of the liquid crystal molecules are different from each other.

[0110] use Figure 6 An example of exposure device 50 and scanning exposure used in this embodiment will be described. Figure 6 In FIG. 1 , the arrow with the symbol W indicates the moving direction (scanning direction) of the substrate 38 relative to the light source 36, and the arrow with the symbol M indicates the transmission axis direction of the polarizing element 37. The scanning direction W corresponds to the “predetermined moving direction”.

[0111] The exposure device 50 includes a light source 36, a photomask 40, and a scanning unit 51. The scanning unit 51 has a mechanism for moving the substrate 38 on which the organic film 29 is formed relative to the light source 36. The photomask 40 is arranged above the substrate 38 with a predetermined interval (proximity gap), and the light source 36 is arranged above the photomask 40. The photomask 40 is provided with a plurality of slits 61. Figure 6 For convenience, only one slit 61 is shown. The slit 61 is equivalent to a "light-transmitting portion". In the exposure device 50, the substrate 38 is moved relative to the light source 36 in the scanning direction W by the scanning unit 51 while irradiating light from the light source 36, thereby scanning and exposing the organic film 29 through the photomask 40. The irradiation light U from the light source 36 passes through the polarizing element 37, and the light vibrating in the transmission axis direction after the transmission passes through the slit 61 of the photomask 40 and irradiates the organic film 29 formed on the substrate 38 from an oblique direction.

[0112] The substrate 38 may be any one of the first substrate 11 and the second substrate 12. In this embodiment, the organic film 29 formed on each of the first substrate 11 and the second substrate 12 is irradiated with linear polarized light by the exposure device 50. By exposing the organic film 29, the organic film 29 is given an inclined azimuth in the same direction along the scanning direction W ( Figure 6 In addition, instead of the structure in which the substrate 38 is moved relative to the light source 36 by the scanning unit 51, a structure in which the light source 36 is moved relative to the substrate 38 may be adopted.

[0113] Here, in the manufacturing process of the liquid crystal display device 10, from the viewpoint of efficiently producing a liquid crystal display device 10 of a large screen size, the organic film 29 formed on a large-sized (for example, G8 size or G10 size) mother substrate may be exposed. Figure 7 In the example shown, the substrate 38 includes eight substrates 38a (first substrate 11 or second substrate 12). It is not practical to expose such a large substrate 38 at one time using a large exposure device 50 or a large photomask in terms of equipment and cost.

[0114] Therefore, in this embodiment, a relatively small photomask 40 is used for the substrate 38, a portion of the organic film 29 is exposed once through the photomask 40, and at least a portion of the remaining portion is exposed repeatedly through the photomask 40. In the case where only the relatively small photomask 40 is connected to the substrate 38 and the entire surface of the organic film 29 is exposed once, the joints between adjacent exposure areas caused by different exposure conditions (for example, different illumination between exposure areas or positional offset of the mask, etc.) are easily visible as brightness differences, and the brightness differences are sometimes visually recognized by the observer as display unevenness. In addition, even if there are slight differences in exposure conditions, when the brightness changes discontinuously, the discontinuous brightness changes are easily visually recognized by the human eye as display unevenness. On the other hand, by providing a portion for repeated exposure between adjacent exposure areas, the rapid change in brightness at the joint of the photomask 40 is suppressed, thereby reducing the occurrence of display unevenness.

[0115] In this embodiment, from the viewpoint of improving production efficiency, a plurality of photomasks 40 are used to expose the substrate surface. Figure 7 As shown in the figure, a plurality of photomasks 40 are arranged in a direction intersecting (preferably orthogonal to) the scanning direction W and along the substrate surface, that is, in the intersecting direction V. The substrate 38 is linearly moved relative to the plurality of photomasks 40 in the scanning direction W, and the organic film 29 is exposed from one end to the other end of the substrate 38 in the scanning direction W by one relative movement of the substrate 38 relative to the light source 36. At this time, a partial area of ​​the organic film 29 is exposed once, and the remaining area is repeatedly exposed.

[0116] Suitable reference Figure 6 and Figure 7 The arrangement of the plurality of photomasks 40 will be described. In the exposure device 50, an exposure unit 52 is provided in which the light source 36 and the photomask 40 are integrated. The exposure unit 52 includes a first photomask 41 and a second photomask 42 as the photomasks 40, the first photomask 41 being arranged on the same line extending in the cross direction V, and the second photomask 42 being arranged further back than the first photomask 41 when viewed in the scanning direction W from the substrate 38 and arranged on the same line extending in the cross direction V. The first photomask 41 and the second photomask 42 are arranged adjacent to each other in the cross direction V, and a part of the adjacent photomasks 40 overlaps each other when viewed in the scanning direction W. The exposure unit 52 is provided with the light source 36 (i.e., a plurality of light sources) corresponding to the number of the photomasks 40, and each light source 36 is integrated with each photomask 40.

[0117] In the exposure device 50, the substrate 38 is moved relative to the exposure unit 52 fixed at a predetermined position by the scanning unit 51, so that the substrate 38 is relatively moved relative to the exposure unit 52. Figure 7 As shown in FIG. 1 , in the organic film 29 on the substrate 38, there are non-overlapping regions 29a where exposure is performed once via the first photomask 41 or the second photomask 42, and overlapping regions 29b where exposure is performed repeatedly via the first photomask 41 and the second photomask 42 ( Figure 7 In the overlapping region 29b, the junction 43 between the first photomask 41 and the second photomask 42 is irradiated with light.

[0118] In order to obtain the liquid crystal display device 10 after orientation division, the organic film 29 is exposed multiple times from different directions. Figure 3 to Figure 5 The half pixel 30a having four liquid crystal domains 31 to 35 shown can be obtained by performing two scanning exposures on the organic film 29 formed on the first substrate 11 and the organic film 29 formed on the second substrate 12, respectively. Specifically, when the substrate 38 for obtaining the first substrate 11 is exposed, first, the slit 61 of the photomask 40 is aligned with the half pixel 30a (more specifically, the half region of the half pixel 30a divided into two parts along the Y-axis direction). Next, while the substrate 38 is moved along the Y-axis direction, polarized ultraviolet rays are irradiated from a direction inclined relative to the substrate surface through the first photomask 41 and the second photomask 42 (first scan). Through the first scan, the half region of the half pixel 30a divided into two parts in the Y-axis direction is given liquid crystal alignment ability. At this time, the pixels 30 included in the overlap region 29b are exposed through the first photomask 41 and the second photomask 42 in an overlapping manner. The total exposure amount of the pixels 30 included in the overlap region 29b (i.e., the total exposure amount through the first photomask 41 and the exposure amount through the second photomask 42) is, for example, 80% to 100% of the exposure amount of the pixels 30 included in the non-overlap region 29a. In the present embodiment, the total exposure amount of the pixels 30 included in the overlap region 29b is equal to the exposure amount of the pixels 30 included in the non-overlap region 29a (approximately 100%).

[0119] Next, the substrate 38 exposed by the first scan is rotated 180° in the plane, and the unexposed area of ​​the half pixel 30a that is not exposed by the first scan is aligned with the slit 61 of the photomask 40. In addition, since the half pixel 30a is a square, the length of the half pixel 30a in the X-axis direction is the same as the length in the Y-axis direction. Thereafter, similarly to the first scan, the substrate 38 is moved in the Y-axis direction while being irradiated with polarized ultraviolet light from a direction inclined relative to the substrate surface through the first photomask 41 and the second photomask 42 (second scan). Thus, as shown in FIG. Figure 3 As shown, on the first substrate 11, a liquid crystal alignment film (first alignment film 22) is formed in two regions dividing the half pixel 30a in the Y-axis direction, wherein the tilt directions of the liquid crystal molecules are antiparallel to each other in the Y-axis direction.

[0120] In addition, the following method is described above: the same exposure unit 52 is used in the first scan and the second scan, and after the substrate 38 is exposed by the first scan, the substrate 38 is rotated 180° in the plane, and then the unexposed area is exposed by the second scan, but the scanning exposure method is not limited to the above. For example, the first scan and the second scan can also be performed by different exposure units. Specifically, a first scanning exposure unit (first exposure unit) whose light irradiation direction is a predetermined direction and a second scanning exposure unit (second exposure unit) whose light irradiation direction is antiparallel to the first exposure unit are provided in the exposure device. Then, after the first scan is performed by the first exposure unit, or during the implementation of the first scan, the unexposed area in the half pixel 30a that is not exposed by the first scan is irradiated with polarized ultraviolet light from a direction inclined relative to the substrate surface by the second exposure unit (second scan). In the above method, it is necessary to configure a large number of scanning light sources or photomasks, but the time required for the exposure process can be shortened.

[0121] When the substrate 38 corresponding to the second substrate 12 is exposed, the process is basically the same as that of the first substrate 11 except that the scanning direction is set to the X-axis direction. By performing two scanning exposures on the substrate 38 corresponding to the second substrate 12, as shown in FIG. Figure 4 As shown in FIG. 1 , a liquid crystal alignment film (second alignment film 23) is formed on the second substrate 12 in two regions that divide the half pixel 30a into two parts in the X-axis direction, and the tilt directions of the liquid crystal molecules are antiparallel to each other in the X-axis direction. Then, the first substrate 11 and the second substrate 12 are arranged with a predetermined interval (cell gap) in such a way that the liquid crystal alignment films face each other, and a liquid crystal layer 13 is provided between the first substrate 11 and the second substrate 12, thereby Figure 5 As shown, a pixel 30 having four liquid crystal domains is obtained.

[0122] <Photomask>

[0123] Next, the structure of the photomask 40 (particularly the mask pattern) is described in detail. The photomask 40 includes a plurality of slits 61 and light shielding portions 62 disposed between the slits 61. The slits 61 and the light shielding portions 62 are alternately arranged. Figure 7 and Figure 8 As shown in FIG. 1 , the first photomask 41 and the second photomask 42 respectively have a non-overlapping region 45 where the first photomask 41 and the second photomask 42 do not overlap when viewed in the scanning direction W, and an overlapping region 46 where the first photomask 41 and the second photomask 42 overlap when viewed in the scanning direction W. Figure 8 Shown in Figure 7 The first photomask 41 and the second photomask 42 are used for the portion corresponding to the region G. The photomask pattern other than the portion corresponding to the region G also has the same photomask pattern as the portion corresponding to the region G.

[0124] The non-overlapping region 45 is a region of the photomask 40 corresponding to a portion of the organic film 29 that is subjected to one exposure. Figure 8 As shown in FIG. 1 , a plurality of slits 61a having the same opening area are provided in the non-overlapping region 45, and a light shielding portion 62a is disposed between each slit 61a. The slits 61a have a rectangular shape (more specifically, a long rectangle) extending in the scanning direction W, and are arranged at the same interval (i.e., equal interval) as the pixel pitch Px in the direction along the cross direction V. The length of the slits 61a in the cross direction V, i.e., the slit width Lx, is, for example, approximately half ±α (μm) of the pixel pitch Px. The length Ly of the slits 61a in the scanning direction W is a predetermined reference length Lyc, for example, about 40 mm.

[0125] The overlapping region 46 is a region of the photomask 40 corresponding to a portion of the organic film 29 to be repeatedly exposed. Figure 8 As shown in FIG. 4 , a plurality of slits 61b having different opening areas are provided in the overlapping region 46, and a light shielding portion 62b is arranged between each slit 61b. The slits 61b are rectangular and are arranged at the same interval (i.e., equal interval) as the pixel pitch Px in the direction along the cross direction V. In addition, the so-called "a plurality of slits having different opening areas" is not limited to a structure that does not include slits having the same opening area, and may include slits 61b having the same opening area as long as the opening areas of at least a portion of the slits 61b are different from each other. The opening area of ​​at least a portion of the slit 61 (slit 61b) arranged in the overlapping region 46 is smaller than the opening area of ​​the slit 61 (slit 61a) arranged in the non-overlapping region 45. The opening area of ​​the slit 61b can be made variable, for example, by adjusting the length Ly.

[0126] In addition, the first photomask 41 and the second photomask 42 may have an overlapping region 46 only at one end portion, or may have overlapping regions 46 at both ends in the crossing direction V, depending on the position in the crossing direction V relative to the substrate 38. In each photomask 40, a photomask 40 disposed at an outer edge portion in the crossing direction V of the substrate 38 only needs to have an overlapping region 46 at at least one of the mask ends. In addition, a photomask 40 disposed at a central portion in the crossing direction V of the substrate 38 may have overlapping regions 46 at both ends in the crossing direction V, and a joint 43 may be formed between the adjacent photomasks 40.

[0127] Here, in the overlapping region 29b where the light is irradiated through the intervening joint 43, a brightness difference is easily generated between the overlapping region 29a and the non-overlapping region 29a due to repeated exposure. Regarding the brightness change of the overlapping region 29b relative to the non-overlapping region 29a, the inventors prepared an evaluation cell made by a single exposure of the organic film 29 and an evaluation cell made by repeated exposure, and compared the brightness of the evaluation cells. As a result, it was found that in the overlapping region 29b, when the exposure amount of each time in the repeated exposure is close, the brightness change becomes larger relative to the non-overlapping region 29a.

[0128] exist Fig. 9 2 shows the results of evaluating the brightness of the evaluation cell produced by single exposure of the organic film 29 and the evaluation cell produced by repeated exposure. Fig. 9 In the brightness evaluation, an evaluation unit is prepared and evaluated by the following method. First, a transparent electrode is formed on a glass substrate, and a liquid crystal orientation agent is applied to the transparent electrode, followed by a heat treatment, thereby forming a photosensitive organic film (organic film 29). Next, the photosensitive organic film formed on the glass substrate is irradiated with polarized ultraviolet rays from a direction inclined relative to the substrate surface, thereby imparting liquid crystal orientation in one direction to form a photo-orientation film. The same operation is performed to prepare two glass substrates with photo-orientation films formed thereon. The two substrates are bonded together with a spacer and a sealing material, and a liquid crystal material with negative dielectric constant anisotropy is injected between the substrates to prepare a vertically oriented evaluation unit. The evaluation unit is clamped by a polarizing plate, and the amount of light transmitted through the evaluation unit is measured when a voltage of 2.3 V is applied between the transparent electrodes.

[0129] A total of four cells were prepared as evaluation cells by applying any of the following conditions (1) to (4) in which the number of exposures to the organic film 29 and the exposure amount of each exposure were different. The irradiation direction of light was the same for all cells.

[0130] (1) Irradiate with polarized ultraviolet light of a standard exposure amount from a direction oblique to the substrate surface

[0131] (2) After irradiating the substrate with polarized ultraviolet light once at an exposure amount of 80% of the reference exposure amount from a direction oblique to the substrate surface, irradiating the substrate with polarized ultraviolet light once at an exposure amount of 20% of the reference exposure amount from a direction oblique to the substrate surface.

[0132] (3) After irradiating the substrate with polarized ultraviolet light once at an exposure amount of 50% of the reference exposure amount from a direction oblique to the substrate surface, irradiating the substrate with polarized ultraviolet light once at an exposure amount of 50% of the reference exposure amount from a direction oblique to the substrate surface

[0133] (4) After irradiating the substrate with polarized ultraviolet light once at an exposure amount of 20% relative to the reference exposure amount from a direction oblique to the substrate surface, irradiating the substrate with polarized ultraviolet light once at an exposure amount of 80% relative to the reference exposure amount from a direction oblique to the substrate surface

[0134] Regarding the evaluation results, the light amount of the transmitted light of the evaluation cell produced by a single exposure at the reference exposure amount (condition (1)) was set to 100, and the light amount of the transmitted light of each evaluation cell was expressed by an index. The results were 100.6% under condition (2), 102.0% under condition (3), and 100.6% under condition (4) (see Fig. 9 ). Based on the results of the brightness evaluation, the following insight was obtained: when repeated exposure was performed according to condition (3), the brightness became higher than when repeated exposure was performed according to condition (2) or condition (4), and the brightness change relative to a single exposure was significantly apparent.

[0135] In addition, the reason for the above-mentioned brightness change is still uncertain, but it is presumed that in the overlapped area 29b subjected to repeated exposure, a reaction different from that in the non-overlapped area 29a subjected to non-overlapping exposure (specifically, a reaction such as a pre-tilt angle of the liquid crystal molecules of the evaluation unit becoming smaller) occurs on the surface of the organic film 29. More specifically, it is believed that the reaction on the film surface accompanied by the oblique irradiation of polarized ultraviolet rays and the chemical reaction that is proportional to the exposure amount during the light irradiation in either the single exposure or the repeated exposure are related to the chemical reaction that is not proportional to the exposure amount due to the relaxation after the light irradiation ends. Here, it is believed that in the case of single exposure, the reaction due to the relaxation after the light irradiation ends is only once, while in the case of repeated exposure, the reaction due to the relaxation after the light irradiation ends is multiple times, and further, in the case of multiple exposures with polarized ultraviolet rays exceeding a certain exposure amount, the influence of each reaction due to the relaxation after the light irradiation ends becomes greater. As a result, it is considered that when multiple exposures are performed with polarized ultraviolet light exceeding a certain exposure amount, the photo-alignment film is subjected to a change in pretilt angle exceeding the total amount of each exposure, and the result is manifested as a change in brightness. However, this is only speculation and does not limit the present invention.

[0136] Based on the above findings, in the present embodiment, the slit 61b provided in the overlapping region 46 of the photomask 40 is set to be a first slit 63 having an opening area of ​​75% or more and 100% or less relative to the opening area (hereinafter, also referred to as "reference area Sc") of the slit 61a arranged in the non-overlapping region 45, or a second slit 64 having an opening area of ​​more than 0% and less than 25% relative to the reference area Sc. As a result, it is avoided that the brightness change in the overlapping region 29b due to the close exposure amount of each time is greatly manifested, and the reduction in display quality caused by the local brightening of the overlapping region 29b is suppressed. In addition, by making the slit 61b in the overlapping region 46 a photomask pattern including the first slit 63 and the second slit 64, the influence of the deviation of the material of the liquid crystal alignment film or the illumination of the light source 36 can be suppressed, and the brightness change in the joint 43 can be suppressed, which is also meaningful in this respect.

[0137] The opening area of ​​the first slit 63 may be within a range of 75% or more and 100% or less. From the viewpoint of sufficiently suppressing local brightening on the display screen corresponding to the overlapping region 29b, the opening area of ​​the first slit 63 is preferably 80% or more. In addition, from the viewpoint of suppressing brightness deviation in the entire overlapping region 29b, the opening area of ​​the first slit 63 is preferably less than 100%, more preferably 99% or less, and further preferably 98% or less.

[0138] The opening area of ​​the second slit 64 only needs to be within the range of more than 0% and less than 25%. From the viewpoint of suppressing the deviation of brightness in the entire overlapping area 29b, the opening area of ​​the second slit 64 is preferably more than 1%, and more preferably more than 2%. In addition, the opening area of ​​the second slit 64 is preferably less than 20%. In addition, the plurality of first slits 63 arranged in the overlapping area 46 may all have the same opening area, or at least a part thereof may have different opening areas. In addition, similarly, the plurality of second slits 64 arranged in the overlapping area 46 may all have the same opening area, or at least a part thereof may have different opening areas.

[0139] The slit width Lx of the first slit 63 and the second slit 64 is the same as that of the slit 61a arranged in the non-overlapping area 45, for example, approximately half of the pixel pitch Px±α (μm). The length Ly of the first slit 63 and the second slit 64 is the same as or shorter than that of the slit 61a, and the shorter the length Ly, the smaller the opening area of ​​the slit 61.

[0140] use Figure 8 The configuration of the slits 61b in the overlapping region 46 will be described in more detail. Figure 8 As shown in FIG. 1 , in each overlapping region 46 of the first photomask 41 and the second photomask 42, the first slits 63 and the second slits 64 are arranged at a predetermined interval corresponding to the pixel pitch Px along the cross direction V. In addition, when viewed in the scanning direction W, the first photomask 41 and the second photomask 42 are positioned so that the first slits 63 arranged in one overlapping region 46 of the first photomask 41 and the second photomask 42 and the second slits 64 arranged in the overlapping region 46 of the other photomask are arranged on the same line extending in the scanning direction W ( Figure 8 on the straight line Ey in the graph).

[0141] exist Figure 8 In the example shown, the length Ly of the first slit 63 is 75% of the reference length Lyc, and has an opening area of ​​75% relative to the reference area Sc. In addition, the length Ly of the second slit 64 is 25% of the reference length Lyc, and has an opening area of ​​25% relative to the reference area Sc. The total opening area of ​​the two slits arranged on the straight line Ey in the first photomask 41 and the second photomask 42 is equal to the reference area Sc. For example, with the center line Ec of the overlapping area 46 extending in the scanning direction W as a reference, the second slit 64 is arranged in the first photomask 41 at the tenth position in the direction from the center line Ec toward the non-overlapping area 45 of the first photomask 41, and the first slit 63 is arranged in the second photomask 42.

[0142] In each overlapping region 46 of the first photomask 41 and the second photomask 42, the second slit 64 is arranged at a position symmetrical to the first slit 63, and the first slit 63 is arranged at a position symmetrical to the second slit 64, with the center line Ec of the overlapping region 46 as the axis. By setting such a configuration, the deviation of the slit opening area in the joint 43 of the first photomask 41 and the second photomask 42 can be suppressed by a simple method. As a result, the uneven brightness change in the entire joint 43 in the cross direction V can be suppressed, and the display unevenness caused by repeated exposure can be suppressed. Figure 8 In the example shown, in the overlapping region 46 of the first photomask 41, the second slit 64 is arranged at the third position in the direction from the center line Ec toward the non-overlapping region 45, and the first slit 63 is arranged at the third position in the direction from the center line Ec toward the mask end 44. In addition, the first slit 63 is arranged at the fifteenth position from the center line Ec toward the non-overlapping region 45, and the second slit 64 is arranged at the fifteenth position in the direction from the center line Ec toward the mask end 44.

[0143] In each overlapping region 46, the slits 61b (i.e., the first slit 63 and the second slit 64) are arranged so that the total opening area ∑S of the slits 61b included in the region of the predetermined length Hx along the cross direction V shows an increasing tendency from the mask end 44 toward the non-overlapping region 45. That is, the first slit 63 and the second slit 64 are combined in each overlapping region 46 so that the exposure amount irradiated to the organic film 29 through each slit 61b shows an increasing tendency from the mask end 44 toward the non-overlapping region 45. Thus, the brightness can be continuously changed in the entire overlapping region 29b, and the brightness change of the transition portion from the overlapping region 29b to the non-overlapping region 29a can be made smoother. As a result, the boundary portion between the overlapping region 29b and the non-overlapping region 29a can be more effectively suppressed from being visually recognized by the observer on the display screen. The method of changing the total opening area ∑S is not particularly limited, and for example, a linear change or a trigonometric function change can also be adopted.

[0144] In addition, the predetermined length Hx is set to a value corresponding to the number of pixels 30 (=pixel pitch Px×number of pixels Nx, where Nx is, for example, 2 or more). For example, when the number of pixels Nx is 5, Figure 8 In the example shown, in the end portion 44 of the first photomask 41, a region ( Figure 8 The total opening area ∑S of the slits included in the area of ​​Hx1 in the first photomask 41 is "(reference area Sc×0.75×1)+(reference area Sc×0.25×4)=reference area Sc×1.75". In addition, the area of ​​the specified length Hx in the central part of the overlapping area 46 of the first photomask 41 ( Figure 8The total opening area ∑S of the slits included in the overlapping area 46 of the first photomask 41 (in the area of ​​Hx2 in the overlap area 46) is "(reference area Sc×0.75×2)+(reference area Sc×0.25×3)=reference area Sc×2.25". The area of ​​the specified length Hx in the adjacent portion of the non-overlapping area 45 in the overlap area 46 of the first photomask 41 ( Figure 8 The sum ∑S of the opening areas of the slits included in the overlapping area 46 of the first photomask 41 (the area Hx3 in the image) is "(reference area Sc×0.75×4)+(reference area Sc×0.25×1)=reference area Sc×3.25". That is, in the overlapping area 46 of the first photomask 41, the sum ∑S of the opening areas shows an increasing trend of "1.75→2.25→3.25" from the mask end 44 toward the non-overlapping area 45. The same is true for the overlapping area 46 of the second photomask 42.

[0145] In each overlapping region 46, the total opening area ΣS shows an increasing tendency from the mask end 44 toward the non-overlapping region 45 according to the density of the discrete first slits 63. That is, in each overlapping region 46, the first slits 63 are densely arranged from the mask end 44 toward the non-overlapping region 45. For example, in Figure 8 In the example shown, the number of first slits 63 included in the Hx1 region is "1", the number of first slits 63 included in the Hx2 region is "2", and the number of first slits 63 included in the Hx3 region is "4". From the mask end 44 toward the non-overlapping region 45, the number of first slits 63 included per unit area (that is, the frequency of the first slits 63) increases. According to the discrete density of the first slits 63, the change of the opening area in the cross direction V can be made smoother by a simple method such as designing the arrangement of the slits 61b. As a result, it is possible to suppress uneven brightness on the display screen caused by repeated exposure without relying on a complicated method.

[0146] In addition, Figure 8 In the example shown, in each overlapping region 46 of the first photomask 41 and the second photomask 42, the second slit 64 is disposed alone at the boundary portion 47 with the non-overlapping region 45, and the first slit 63 is disposed alone at the mask end portion 44. Even when the second slit 64 is disposed at the boundary portion 47, if the second slit 64 is disposed alone, it is possible to suppress a sharp change in the slit opening area at the boundary portion 47. Therefore, in the above case, it is possible to suppress a sharp change in brightness between the overlapping region 29b and the non-overlapping region 29a, and to suppress the occurrence of display unevenness at the junction portion 43.

[0147] In the present embodiment described above, considering that the brightness change in the overlap region 29b becomes larger when the exposure amounts of each time in the repeated exposure are close, the slit 61b arranged in the overlap region 46 of the photomask 40 is set to be the first slit 63 having an opening area of ​​75% or more and 100% or less with respect to the reference area Sc, or the second slit 64 having an opening area of ​​more than 0% and 25% or less with respect to the reference area Sc. This can prevent the overlap region 29b from being locally brightened due to the close exposure amounts of each time in the overlap region 29b, and as a result, it is possible to prevent the display defect of the liquid crystal display device 10.

[0148] In addition, in the present embodiment, when viewed in the scanning direction W, the first slit 63 disposed in the overlapping region 46 of one of the first photomask 41 and the second photomask 42 and the second slit 64 disposed in the overlapping region 46 of the other photomask are disposed on the straight line Ey. Thus, it is possible to suppress the occurrence of a brightness deviation due to a deviation in exposure in the entire overlapping region 29b, and as a result, it is possible to suppress the occurrence of display unevenness in the entire overlapping region 29b. In addition, the change in exposure at the boundary portion between the non-overlapping region 29a and the overlapping region 29b can be smoothed, and it is possible to suppress the visual recognition of the joint 43 on the display screen.

[0149] In particular, by making the opening area of ​​the first slit 63 less than 100%, the first slit 63 and the second slit 64 can be arranged on the straight line Ey, and the total opening area of ​​the first slit 63 and the second slit 64 arranged on the straight line Ey can be equal to the reference area Sc. As a result, the change in the exposure amount at the boundary portion of the non-overlapping area 29a and the overlapping area 29b can be made smoother, and the joint 43 can be effectively suppressed from being visually recognized on the display screen.

[0150] Furthermore, in the present embodiment, the slits 61b are arranged in the overlapping regions 46 of the first photomask 41 and the second photomask 42 so that the total opening area ΣS shows an increasing tendency from the mask end 44 toward the non-overlapping region 45 according to the density of the discrete first slits 63. Therefore, the effect of suppressing the increase in brightness due to the arrangement of the first slits 63 and the second slits 64 can be obtained, and the change in the opening area of ​​the slits 61b is smoothed in the boundary portion between the joint 43 and the non-overlapping region 45 and in the entire joint 43.

[0151] This embodiment is not limited to the above-described form, and can be implemented in the following forms, for example.

[0152] In the above embodiment, the opening area of ​​the first slit 63 is 75% of the reference area Sc, and the opening area of ​​the second slit 64 is 25% of the reference area Sc. However, the opening area of ​​the first slit 63 only needs to be 75% or more and 100% or less of the reference area Sc, and the opening area of ​​the second slit 64 only needs to be more than 0% and less than 25% of the reference area Sc. For example, Fig.10 As shown in FIG. 1 , the opening area of ​​the first slit 63 may be 90% of the reference area Sc, and the opening area of ​​the second slit 64 may be 10% of the reference area Sc. In consideration of ease of design or the limit of light transmission, the opening area of ​​the second slit 64 is preferably 1% to 25% of the reference area Sc, and more preferably 2% to 25%.

[0153] In the above embodiment, the opening areas of all the first slits 63 are made the same, and the opening areas of all the second slits 64 are made the same. However, as long as the opening area of ​​the first slit 63 is 75% or more and 100% or less of the reference area Sc, and the opening area of ​​the second slit 64 is more than 0% and less than 25% of the reference area Sc, the first slit 63 and the second slit 64 may include slits with different opening areas. For example, the first slit 63 may include a slit with an opening area of ​​80% of the reference area Sc and a slit with an opening area of ​​90% of the reference area Sc. Similarly, the second slit 64 may include a slit with an opening area of ​​20% of the reference area Sc and a slit with an opening area of ​​10% of the reference area Sc.

[0154] In the above embodiment, in the respective overlapping regions 46 of the first photomask 41 and the second photomask 42, the total opening area of ​​the two slits arranged on the straight line Ey is made equal to the reference area Sc (that is, 100% relative to the reference area Sc), but the present invention is not limited to the above structure. For example, the total opening area of ​​the two slits arranged on the straight line Ey is, for example, 80% to 99% of the reference area Sc. In addition, instead of making the total opening area of ​​the two slits arranged on the straight line Ey the same throughout the joint 43, the total opening area of ​​the two slits arranged on the straight line Ey may be variable in the joint 43. For example, the total opening area of ​​the two slits arranged on the straight line Ey may be reduced linearly or trigonometrically from the end portion of the joint 43 toward the center portion.

[0155] In the above embodiment, the second slit 64 is arranged at a position symmetrical to the first slit 63 with the center line Ec as the axis, and the first slit 63 is arranged at a position symmetrical to the second slit 64, but the present invention is not limited thereto, and the first slit 63 may be arranged at a position symmetrical to the first slit 63 with the center line Ec as the axis. In addition, the second slit 64 may be arranged at a position symmetrical to the second slit 64 with the center line Ec as the axis.

[0156] Second Implementation Method

[0157] Next, a second embodiment of the manufacturing method of the present disclosure is described. In the second embodiment, the configuration (photomask pattern) of the slit 61 in the joint 43 of the photomask 40 is different from that in the first embodiment. In addition, in the following description, the description of the same structure as the first embodiment is omitted, and the description is centered on the differences from the first embodiment.

[0158] Fig.11 The structure of the photomask 40 in the second embodiment is shown in FIG. The overlapping region 46 of each of the first photomask 41 and the second photomask 42 in this embodiment has a first section F1 adjacent to the non-overlapping region 45, and a second section F2 including the mask end 44. The first slit 63 is arranged in the first section F1, and the second slit 64 is not arranged. In addition, the second slit 64 is arranged in the second section F2, and the first slit 63 is not arranged. Fig.11 In the example shown, of the two sections divided by the center line Ec, the area including the boundary portion 47 with the non-overlapping area 45 is the first section F1, and the area including the mask end portion 44 is the second section F2. By arranging the first section F1 including the first slit 63 at the boundary portion with the non-overlapping area 45 in the joint 43 between the first photomask 41 and the second photomask 42, the exposure amount to the organic film 29 can be continuously changed at the boundary portion between the non-overlapping area 29a and the overlapping area 29b. As a result, it is possible to effectively suppress the brightness change in the overlapping area 29b from being visually recognized as display unevenness.

[0159] A plurality of first slits 63 are arranged in the first section F1. The plurality of first slits 63 arranged in the first section F1 preferably have an opening area that decreases in a direction away from the non-overlapping region 45. Thus, the exposure amount at the boundary between the non-overlapping region 29a and the overlapping region 29b can be continuously changed along the cross direction V, and the brightness change in the overlapping region 29b can be more effectively suppressed. Fig.11In the example shown, in the first section F1, by changing the length Ly of each slit, the opening area of ​​the first slit 63 gradually decreases (preferably monotonically decreases) from 99% to 75% of the reference area Sc. In addition, the length Ly of the first first slit 63 from the center line Ec is 75% of the reference length Lyc, and the opening area is 75% of the reference area Sc. The decrease in the opening area of ​​the first slit 63 in the first section F1 may be linear or trigonometric.

[0160] A plurality of second slits 64 are arranged in the second section F2. The plurality of second slits 64 arranged in the second section F2 preferably have an opening area that becomes smaller in the direction toward the mask end 44. Thus, the exposure amount of the boundary portion between the non-overlapping area 29a and the overlapping area 29b can be continuously changed along the cross direction V, while the opening area of ​​the two slits 61 arranged on the straight line Ey in the joint 43 can be adjusted to a desired range. As a result, brightness changes are less likely to occur in the entire joint 43. Fig.11 In the example shown, the length Ly of the second slit 64 arranged at the first position from the center line Ec in the second section F2 is 25% of the reference length Lyc, and the opening area is 25% of the reference area Sc. In addition, in the second section F2, the opening area of ​​the second slit 64 gradually decreases (preferably monotonically decreases) from 25% of the reference area Sc in the direction from the center line Ec toward the mask end 44. The decrease in the opening area of ​​the second slit 64 in the second section F2 may be linear or trigonometric.

[0161] The second embodiment described above exerts the same effects as those of the first embodiment. In addition, according to the second embodiment, since a plurality of first slits 63 are arranged in the first section F1 adjacent to the non-overlapping region 45 in the joint portion 43, the exposure amount of the boundary portion between the non-overlapping region 29a and the overlapping region 29b can be continuously changed along the cross direction V. Thus, a sharp brightness change in the overlapping region 29b can be effectively suppressed.

[0162] In particular, in the first interval F1, the opening area of ​​the first slit 63 is reduced in the direction away from the non-overlapping region 45, so that the exposure amount at the boundary between the non-overlapping region 29a and the overlapping region 29b can be changed continuously and smoothly. As a result, a sharp brightness change in the overlapping region 29b can be more effectively suppressed.

[0163] In addition, in the above embodiment, the opening area of ​​the first slit 63 is gradually reduced toward 75% of the reference area Sc, and the opening area of ​​the second slit 64 is gradually reduced from 25% of the reference area Sc in the first section F1, but the lower limit of the opening area of ​​the first slit 63 and the upper limit of the opening area of ​​the second slit 64 are not limited to the above. For example, Fig.12 As shown in FIG. 1 , the first slit 63 may be gradually shortened in length Ly toward 90% of the reference length Lyc so that the opening area gradually decreases toward 90% of the reference area Sc. At this time, the second slit 64 may be gradually shortened in length Ly from 10% of the reference length Lyc so that the opening area gradually decreases from 10% of the reference area Sc.

[0164] In the second embodiment, a decreasing section in which the opening area of ​​the first slit 63 gradually decreases in the direction away from the non-overlapping region 45 and a fixed section in which the opening area of ​​the first slit 63 is constant may be provided in the first section F1. The number or combination of the decreasing section and the fixed section in the first section F1 is not particularly limited. For example, the decreasing section may be arranged adjacent to the non-overlapping region 45 in the first section F1, and the fixed section may be arranged adjacent to the decreasing section. In addition, the decreasing section, the fixed section, and the decreasing section may be arranged in sequence in the direction from the non-overlapping region toward the center line Ec.

[0165] 《Third Implementation Mode》

[0166] Next, the third embodiment of the manufacturing method of the present disclosure is described. In the third embodiment, the configuration (photomask pattern) of the slit 61 in the joint 43 of the photomask 40 is different from that in the first and second embodiments. Specifically, in addition to the first section F1 and the second section F2 in the second embodiment, the photomask 40 of the third embodiment also has a third section F3 disposed between the first section F1 and the second section F2. In addition, in the following description, the description of the same structure as the first and second embodiments is omitted, and the description is centered on the differences from the first and second embodiments.

[0167] Fig.13 The structure of the photomask 40 in the third embodiment is shown in FIG. The overlapping region 46 of each of the first photomask 41 and the second photomask 42 in this embodiment has a first section F1 adjacent to the non-overlapping region 45 and a second section F2 including the mask end 44. Fig.13In the example shown, in the two sections divided by the center line Ec, a portion of the region including the boundary portion 47 with the non-overlapping region 45 becomes the first section F1, and a portion of the region including the mask end portion 44 becomes the second section F2. The length Ly or arrangement of the slits 61 in the first section F1 and the second section F2 are the same as those in the second embodiment.

[0168] The third section F3 is provided between the first section F1 and the second section F2 in the joint portion 43. A plurality of first slits 63 are arranged in the third section F3. Fig.13 In the example shown, the third section F3 has the same photomask pattern as the overlapping region 46 in the first embodiment.

[0169] Specifically, in the third section F3, the slits 61b are arranged at the same interval (i.e., equal interval) as the pixel pitch Px in the direction along the cross direction V. In addition, the first slit 63 and the second slit 64 are arranged as the slits 61b in the third section F3. The length Ly of the first slit 63 is 75% of the reference length Lyc, and has an opening area of ​​75% relative to the reference area Sc. In addition, the length Ly of the second slit 64 is 25% of the reference length Lyc, and has an opening area of ​​25% relative to the reference area Sc. In the first photomask 41 and the second photomask 42, the total opening area of ​​the two slits arranged on the straight line Ey is equal to the reference area Sc. Furthermore, in the third sections F3 of the first photomask 41 and the second photomask 42, the second slit 64 is arranged at a position symmetrical to the first slit 63 with the center line Ec of the overlapping area 46 as the axis, and the first slit 63 is arranged at a position symmetrical to the second slit 64.

[0170] In the third section F3, the sum ∑S of the opening areas of the slits 61b included in the region of the predetermined length Hx shows an increasing tendency in the direction from the second section F2 toward the first section F1, depending on the density of the discreteness of the first slits 63. That is, in the third section F3, the first slits 63 are densely arranged in the direction from the second section F2 toward the first section F1. The increase in the opening area of ​​the slits 61b in the third section F3 may be linear or trigonometric. Fig.13 In the example shown, in the third section F3, the first slits 63 and the second slits 64 are arranged such that the slits 61b including the first slits 63 and the second slits 64 are equally spaced and the number of the first slits 63 included per unit area (ie, the frequency of the first slits 63) increases.

[0171] The third embodiment described above exerts an effect corresponding to the same structure as the first embodiment. In addition, in the third embodiment, in addition to the first section F1 and the second section F2, the third section F3 is further provided between the first section F1 and the second section F2 in the photomask 40. In the third section F3, the first slits 63 are closely arranged in the direction from the second section F2 toward the first section F1, so that the effect of suppressing the increase in brightness brought about by the arrangement of the first slits 63 can be obtained, and the change in the opening area of ​​the slit 61b in the joint 43 becomes smooth. In addition, since the first section F1 is provided at a position adjacent to the non-overlapping area 45 in the joint 43, the change in the exposure amount in the boundary portion between the non-overlapping area 29a and the overlapping area 29b can be made to be a continuous change, and the occurrence of a sharp brightness change in the overlapping area 29b can be effectively suppressed.

[0172] In addition, in the above embodiment, the opening area of ​​the first slit 63 is gradually reduced toward 75% of the reference area Sc in the first section F1, and the opening area of ​​the second slit 64 is gradually reduced from 25% of the reference area Sc, and the opening area of ​​the first slit 63 in the third section F3 is set to 75% of the reference area Sc, and the opening area of ​​the second slit 64 is set to 25% of the reference area Sc, but the opening area of ​​the first slit 63 and the opening area of ​​the second slit 64 are not limited to the above. For example, Fig.14 As shown, with respect to the first slit 63, the opening area of ​​the first slit 63 is set to be greater than 90% of the reference area Sc by ensuring that the length Ly is not less than 90% of the reference length Lyc, and with respect to the second slit 64, the opening area of ​​the second slit 64 can also be set to be less than 10% of the reference area Sc by ensuring that the length Ly does not exceed 10% of the reference length Lyc.

[0173] In the third embodiment, a decreasing section in which the opening area of ​​the first slit 63 gradually decreases in the direction away from the non-overlapping region 45 and a constant section in which the opening area of ​​the first slit 63 is constant may be provided in the first section F1. Also, a constant section in which the opening area of ​​the second slit 64 is constant and a decreasing section in which the opening area of ​​the second slit 64 gradually decreases toward the mask end 44 may be provided in the second section F2.

[0174] 《Fourth Implementation Mode》

[0175] Next, the fourth embodiment of the manufacturing method of the present disclosure is described. In the fourth embodiment, the configuration (photomask pattern) of the slits 61 in the joint 43 of the photomask 40 is different from that of the first to third embodiments. Specifically, the photomask 40 of the fourth embodiment has a first section F1, a second section F2, and a third section F3 in the respective overlapping regions 46 of the first photomask 41 and the second photomask 42, as in the third embodiment. Among them, in the photomask 40 of the fourth embodiment, the third section F3 is different from the third embodiment in that it has the first slit 63 but not the second slit 64, and the slits 61b are not arranged at equal intervals. In the following description, the description of the same structure as the first to third embodiments is omitted, and the description is centered on the differences from the first to third embodiments.

[0176] Fig.15 . The structure of the photomask 40 of the fourth embodiment is shown in FIG. The first slit 63 arranged in the third section F3 is the same as the slit 61a arranged in the non-overlapping area 45, the length Ly is the reference length Lyc, and the opening area is the reference area Sc. In the third section F3, by changing the distribution density of the first slits 63 in the cross direction V, the first slits 63 are densely arranged in the direction from the second section F2 toward the first section F1. As a result, the sum ∑S of the opening areas of the slits 61b included in the region of the predetermined length Hx shows an increasing tendency in the direction from the second section F2 toward the first section F1. When observed in the scanning direction W, on the straight line Ey, the first slit 63 is arranged on one of the first photomask 41 and the second photomask 42, and the light shielding portion 62b is arranged on the other photomask.

[0177] According to the mask pattern of the photomask 40 of the fourth embodiment, since the first slits 63 are closely arranged in the direction from the second section F2 toward the first section F1 in the third section F3, the effect of suppressing the increase in brightness due to the arrangement of the first slits 63 can be obtained, and the change in the opening area of ​​the slit 61b in the joint 43 is smoothed. In addition, since the first section F1 is provided at a position adjacent to the non-overlapping region 45 in the joint 43, the change in the exposure amount in the boundary portion between the non-overlapping region 29a and the overlapping region 29b can be made to be a continuous change, and as a result, the display unevenness caused by the rapid brightness change in the overlapping region 29b can be effectively suppressed.

[0178] The liquid crystal display device 10 of the present disclosure described above can be effectively applied to various applications. For example, the liquid crystal display device 10 can be used as various display devices such as clocks, portable game consoles, word processors, notebook personal computers, car navigation systems, camcorders, personal digital assistants (PDAs), digital cameras, mobile phones, smartphones, various monitors, liquid crystal televisions, and information displays.

[0179] In addition, if Fig.16 As shown in the photomask 100, when the opening area of ​​the slit 61 is not changed but only two photomasks are connected to form a joint 43, the brightness difference between the two adjacent light sources is displayed on the display screen as the brightness difference between the joint between the exposure area of ​​one photomask and the exposure area of ​​the other photomask, and the joint is easily visually recognizable by the observer.

[0180] in addition, Fig.17 In the photomask 200 shown in the figure, the halftone portion has a slit 61 at the junction 43, where the opening area of ​​the slit 61 decreases continuously in the direction from the non-overlapping region 45 toward the mask end 44. In the exposure of the intermediate photomask 200, the slit 61 with an opening area close to the exposure amount in each repeated exposure is arranged at the junction 43 ( Fig.17 Therefore, in the joint portion 43, the area where the exposure amounts are close to each other becomes locally brighter, thereby causing band-shaped unevenness on the display screen, which is likely to lead to a decrease in display quality.

Claims

1. A method for manufacturing a liquid crystal display device, wherein: The liquid crystal display device includes: a substrate, a photo-alignment film formed on the substrate, and a liquid crystal layer adjacent to the photo-alignment film. The method for manufacturing a liquid crystal display device includes an exposure step of exposing the organic film to light through a photomask while relatively moving a substrate having a photosensitive organic film formed thereon in a predetermined moving direction relative to a light source. The exposure step exposes a portion of the organic film once and repeatedly exposes at least a portion of the remaining region. The photomask has a plurality of light-transmitting portions having the same opening area and a light-shielding portion disposed between the light-transmitting portions in a non-overlapping region corresponding to a portion of the organic film to be exposed once, and has a plurality of light-transmitting portions having different opening areas and a light-shielding portion disposed between the light-transmitting portions in an overlapping region corresponding to a portion of the organic film to be exposed repeatedly, The opening area of ​​at least a portion of the plurality of light-transmitting portions arranged in the overlapping region is smaller than the opening area of ​​the light-transmitting portion arranged in the non-overlapping region. Each light-transmitting portion arranged in the overlapping area is a first light-transmitting portion having an opening area greater than 75% and less than 100% of the opening area of ​​each light-transmitting portion arranged in the non-overlapping area, or a second light-transmitting portion having an opening area greater than 0% and less than 25%.

2. The method for manufacturing a liquid crystal display device according to claim 1, wherein: The photomask includes a first photomask and a second photomask arranged adjacent to each other along a direction intersecting the moving direction and along the substrate surface, i.e., the intersecting direction, wherein the first photomask and the second photomask are arranged so that parts of each other overlap when viewed in the moving direction. The non-overlapping area is an area where the first photomask and the second photomask do not overlap when viewed in the moving direction. The overlapping region is a region where the first photomask and the second photomask overlap when viewed in the moving direction.

3. The method for manufacturing a liquid crystal display device according to claim 2, wherein: The first light-transmitting portion arranged in the overlapping region of one of the first photomask and the second photomask and the second light-transmitting portion or the light-shielding portion arranged in the overlapping region of the other photomask are arranged on the same line extending in the moving direction.

4. The method for manufacturing a liquid crystal display device according to claim 2 or 3, wherein: In the overlapping region, the light-transmitting portions are arranged so that the total opening area of ​​the light-transmitting portions included in a region of a predetermined length along the intersecting direction tends to increase from an end portion of the photomask toward the non-overlapping region.

5. The method for manufacturing a liquid crystal display device according to claim 4, wherein: In the overlapping region, the first light-transmitting portions are densely arranged from an end portion of the photomask toward the non-overlapping region.

6. The method for manufacturing a liquid crystal display device according to claim 2 or 3, wherein: The overlapping region has a first section adjacent to the non-overlapping region and a second section including an end portion of the photomask. The first light-transmitting portion is disposed in the first interval, and the second light-transmitting portion is not disposed. The second light-transmitting portion is disposed in the second section, but the first light-transmitting portion is not disposed.

7. The method for manufacturing a liquid crystal display device according to claim 6, wherein: A plurality of the first light-transmitting portions are arranged in the first interval. The opening area of ​​each first light-transmitting portion arranged in the first section decreases in a direction away from the non-overlapping region.

8. The method for manufacturing a liquid crystal display device according to claim 6, wherein: A plurality of the second light-transmitting portions are arranged in the second interval, The opening area of ​​each second light-transmitting portion arranged in the second section becomes smaller in a direction toward an end portion of the photomask.

9. The method for manufacturing a liquid crystal display device according to claim 6, wherein: The overlapping region further has a third section disposed between the first section and the second section. In the third section, the first light-transmitting portions are densely arranged from the second section toward the first section.

10. The method for manufacturing a liquid crystal display device according to claim 9, wherein: The opening area of ​​each first light-transmitting portion arranged in the first section becomes smaller in a direction away from the non-overlapping area. The opening area of ​​each second light-transmitting portion arranged in the second section becomes smaller in a direction toward an end portion of the photomask.

11. The method for manufacturing a liquid crystal display device according to claim 2 or 3, wherein: In the overlapping area, the second light-transmitting portion or the light-shielding portion is arranged at a position symmetrical to the first light-transmitting portion with the center line of the overlapping area extending in the moving direction as the axis, and the first light-transmitting portion is arranged at a position symmetrical to the second light-transmitting portion.

12. The method for manufacturing a liquid crystal display device according to claim 1 or 2, wherein: The liquid crystal display device has two or more regions in which the alignment directions of liquid crystal molecules in the liquid crystal layer are different within one pixel.

13. The method for manufacturing a liquid crystal display device according to claim 1 or 2, wherein: In the exposure step, polarized ultraviolet rays are irradiated from a direction oblique to the substrate surface.

14. The method for manufacturing a liquid crystal display device according to claim 1 or 2, wherein: The liquid crystal layer contains liquid crystal molecules having negative dielectric anisotropy. 15 . A liquid crystal display device manufactured by the method for manufacturing a liquid crystal display device according to claim 1 or 2.

16. An exposure device for manufacturing a photo-alignment film, the exposure device comprising: light source; multiple photomasks; as well as a scanning unit that exposes the organic film through the plurality of photomasks while moving the substrate having the photosensitive organic film relative to the light source in a predetermined moving direction; The plurality of photomasks are arranged in a direction intersecting the moving direction and along the substrate surface, that is, in an intersecting direction, and include a first photomask and a second photomask adjacent to the first photomask. The first photomask and the second photomask are arranged so that parts of each other overlap when viewed in the moving direction. The first photomask and the second photomask respectively have a plurality of light-transmitting portions with the same opening area and a light-shielding portion disposed between the light-transmitting portions in a non-overlapping region where the first photomask and the second photomask do not overlap when viewed in the moving direction, and have a plurality of light-transmitting portions with different opening areas and a light-shielding portion disposed between the light-transmitting portions in an overlapping region where the first photomask and the second photomask overlap when viewed in the moving direction. The opening area of ​​at least a portion of the plurality of light-transmitting portions arranged in the overlapping region is smaller than the opening area of ​​the light-transmitting portion arranged in the non-overlapping region. Each light-transmitting portion arranged in the overlapping area is a first light-transmitting portion having an opening area greater than 75% and less than 100% of the opening area of ​​each light-transmitting portion arranged in the non-overlapping area, or a second light-transmitting portion having an opening area greater than 0% and less than 25%.

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