Method for manufacturing liquid crystal display device and exposure device

Abstract

To provide a method for manufacturing a liquid crystal display device in which the occurrence of display unevenness caused by overlapping exposure can be suppressed by a relatively simple method.SOLUTION: There is provided a method for manufacturing a liquid crystal display device which comprises an exposure step of exposing an organic film via a photomask 40. In the exposure step, a portion of the organic film is subjected to single exposure and at least a portion of the remaining organic film is subjected to overlapping exposure. The photomask 40 has a plurality of slits 61a and a plurality of light-shielding portions 62a in a non-overlapping area 45 corresponding to the single exposure and a plurality of slits 61b having different opening areas and light-shielding portions 62b provided between respective slits 61b in an overlapping area 46 corresponding to the overlapping exposure. At least a part of the slits 61b has a smaller opening area than the slits 61a. Each slit 61b is either a first slit 63 having an opening area of 75% or more and 100% or less of that of each slit 61a, or a second slit 64 having an opening area of more than 0% and 25% or less.SELECTED DRAWING: Figure 8

Description

[Technical field]

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

[0002] For LCD displays, especially LCD panels for large TVs, viewing angle, transmittance, response time, etc. are important performance indicators. Various LCD display modes have been developed to improve the values ​​of these performance indicators, such as 4D-RTN (4-Domain-Reverse Twisted Nematic) mode, 4D-ECB mode (4-Domain-Electrically Controlled Birefringence), PSA (Polymer Sustained Alignment) mode, IPS (In Plane Switching) mode, FFS (Fringe Field Switching) mode, etc. Currently, large TVs using these LCD display mode technologies are being mass-produced.

[0003] A liquid crystal display device is provided with a liquid crystal alignment film for controlling the alignment of liquid crystal molecules in a liquid crystal cell. Known methods for obtaining a liquid crystal alignment film include a method of rubbing an organic film, a method of obliquely depositing 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-alignment method), and the like. Among these, the photo-alignment method can impart a uniform liquid crystal alignment ability to a photosensitive organic film while suppressing the generation of static electricity and dust, and also enables precise control of the alignment direction of the liquid crystal molecules, and various studies are being conducted. When imparting a liquid crystal alignment ability to a photosensitive organic film by the photo-alignment method, the organic film is usually irradiated with light through a photomask.

[0004] In the manufacturing process of liquid crystal display devices, productivity is improved by obtaining multiple substrates of a size corresponding to one liquid crystal display device from one mother substrate. However, when a large-sized (e.g., 60- or 70-inch class) liquid crystal display device is manufactured by a photo-alignment method, it is not realistic to irradiate a large-sized substrate from which multiple substrates corresponding to a large screen size can be obtained with light at once by one exposure. In addition, an increase in the size of the photomask leads to an increase in manufacturing costs. Furthermore, even when a relatively small-sized (e.g., 20- or 30-inch class) liquid crystal display device is manufactured, it is considered that there is an increasing need for a smaller exposure device in order to reduce manufacturing costs.

[0005] Therefore, when manufacturing a liquid crystal display device by the photo-alignment method, a study is being conducted on dividing the exposure area on the substrate into several parts and arranging multiple photomasks of a size corresponding to each exposure area for exposure. However, when the exposure area is divided into several parts for exposure, the seams between the exposure areas may appear on the screen as display unevenness.

[0006] In order to cope with the above-mentioned problem of uneven display, it has been proposed to improve the photomask pattern to make the seams between the exposed regions less visible on the display screen (see, for example, Patent Document 1). Patent Document 1 discloses that the substrate surface is divided into two or more exposed regions, and when exposing an organic film through a photomask for each exposed region, the adjacent exposed regions are exposed so that a part of them overlap, and a photomask having a halftone portion is used in the region corresponding to the overlapped exposed region. The photomask of Patent Document 1 has a plurality of slits in the halftone portion, and the aperture ratio of the plurality of slits continuously decreases in the direction toward the mask end. Patent Document 1 also discloses that the total irradiation amount of the overlapping exposed region is controlled, thereby making the seams between the exposed regions less visible. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2007 / 086474 Summary of the Invention [Problem to be solved by the invention]

[0008] The inventors have studied the method described in Patent Document 1 and found that although the brightness jump at the seam between exposed regions is suppressed, the seam may be locally bright. In addition, the method of making the seam between exposed regions less visible by controlling the total irradiation amount of the overlapping exposed regions requires optimizing the photomask pattern according to the total irradiation amount of the overlapping exposed regions every time various conditions such as the material of the liquid crystal alignment film and the illuminance of the light source change, and there is a concern that the method of suppressing display unevenness will become complicated.

[0009] The present invention has been made in consideration of the above problems, and has as its main object to provide a manufacturing method for a liquid crystal display device that can suppress the occurrence of display unevenness caused by overlapping exposure using a relatively simple technique. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention employs the following means.

[0011] [1] A method for manufacturing a liquid crystal display device comprising a substrate, a photo-alignment film formed on the substrate, and a liquid crystal layer adjacent to the photo-alignment film, the method comprising the steps of: exposing a photosensitive organic film formed on the substrate to light through a photomask while moving the substrate in a predetermined moving direction relative to a light source; the exposure step performing a single exposure on a partial region of the organic film, and performing overlapping exposure on at least a partial region of the remaining region; the photomask is provided with a plurality of light-transmitting portions having the same opening area and a plurality of light-transmitting portions provided between the light-transmitting portions in non-overlapping regions corresponding to the portions of the organic film that are to be exposed once. and a light-shielding portion disposed between each of the light-transmitting portions in an overlapping region corresponding to a portion of the organic film that is subjected to overlapping exposure, wherein at least a portion of the light-transmitting portions disposed in the overlapping region has a smaller opening area than a light-transmitting portion disposed in the non-overlapping region, and each light-transmitting portion disposed in the overlapping region is a first light-transmitting portion having an opening area that is 75% or more and 100% or less of the opening area of ​​each light-transmitting portion disposed in the non-overlapping region, or a second light-transmitting portion having an opening area that is more than 0% and 25% or less.

[0012] [2] The method for manufacturing a liquid crystal display device described in [1] above, wherein the photomask includes a first photomask and a second photomask arranged adjacent to each other along a cross direction that crosses the movement direction and is a direction along the substrate surface, the first photomask and the second photomask are arranged so that portions of each photomask overlap as viewed in the movement direction, the non-overlapping region is a region where the first photomask and the second photomask do not overlap as viewed in the movement direction, and the overlapping region is a region where the first photomask and the second photomask overlap as viewed in the movement direction. [3] The method for manufacturing a liquid crystal display device described in [2] above, 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 movement direction. [4] The method for manufacturing a liquid crystal display device described in [2] or [3] above, wherein the light-transmitting portions are arranged in the overlapping region such that the sum of the opening areas of the light-transmitting portions included in a region of a predetermined length along the intersecting direction shows an increasing tendency from the edge of the photomask toward the non-overlapping region. [5] The method for manufacturing a liquid crystal display device according to any one of [1] to [4] above, wherein in the overlapping region, the first light transmitting portions are densely arranged from an end of the photomask toward the non-overlapping region. [6] The method for manufacturing a liquid crystal display device according to any one of [1] to [5] above, wherein the overlapping region has a first section adjacent to the non-overlapping region and a second section including an end of a photomask, the first light transmitting section being arranged in the first section and the second light transmitting section not being arranged, and the second light transmitting section being arranged in the second section and the first light transmitting section not being arranged. [7] The method for manufacturing a liquid crystal display device described in [6] above, wherein a plurality of the first light-transmitting portions are arranged in the first section, and the opening area of ​​each of the first light-transmitting portions 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 described in [6] or [7] above, wherein a plurality of the second light-transmitting portions are arranged in the second section, and an opening area of ​​each of the second light-transmitting portions arranged in the second section decreases in a direction toward the end of the photomask.

[0013] [9] The method for manufacturing a liquid crystal display device described in any one of [6] to [8] above, wherein the overlapping region further has a third section provided between the first section and the second section, and in the third section, the first light transmitting sections are densely arranged from the second section to the first section.

[10] The method for manufacturing a liquid crystal display device described in [9] above, wherein an opening area of ​​each first light-transmitting portion arranged in the first section decreases in a direction away from the non-overlapping region, and an opening area of ​​each second light-transmitting portion arranged in the second section decreases in a direction toward the end of the photomask.

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

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

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

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

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

[12] , wherein in the exposure step, polarized ultraviolet light is irradiated obliquely onto the substrate surface.

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

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

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

[14] .

[0014]

[16] An exposure apparatus for manufacturing a photo-alignment film, comprising: a light source; a plurality of photomasks; and a scanning unit for exposing a substrate having a photosensitive organic film through the plurality of photomasks while moving the substrate in a predetermined moving direction relative to the light source, the plurality of photomasks being arranged side by side in a cross direction that crosses the moving direction and is a direction along a substrate surface, the plurality of photomasks including a first photomask and a second photomask adjacent to the first photomask, the first photomask and the second photomask being arranged such that a portion of each of the first photomask and the second photomask overlap each other as viewed in the moving direction, and a plurality of light-transmitting portions having different opening areas and light-shielding portions provided between the light-transmitting portions in a non-overlapping region where the first photomask and the second photomask do not overlap as viewed in the movement direction, and a plurality of light-transmitting portions having different opening areas and light-shielding portions provided between the light-transmitting portions in an overlapping region where the first photomask and the second photomask overlap as viewed in the movement direction, at least a portion of the plurality of light-transmitting portions arranged in the overlapping region has a smaller opening area than the light-transmitting portions arranged in the non-overlapping region, and each light-transmitting portion arranged in the overlapping region is a first light-transmitting portion having an opening area that is 75% or more and 100% or less of the opening area of ​​each light-transmitting portion arranged in the non-overlapping region, or a second light-transmitting portion having an opening area that is more than 0% and 25% or less. Effect of the Invention

[0015] According to the present invention, display unevenness that occurs in a liquid crystal display device due to overlapping exposure can be suppressed by a relatively simple method of designing a photomask pattern by combining and arranging a first light-transmitting portion and a second light-transmitting portion, each of which has an opening area within a predetermined range, in an overlapping region corresponding to the area where overlapping exposure is performed. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a cross-sectional view illustrating a schematic configuration of a liquid crystal display device. [Diagram 2] FIG. [Diagram 3]FIG. 4 is a diagram showing the direction in which light is irradiated onto an organic film on a first substrate. [Figure 4] FIG. 4 is a diagram showing the direction in which light is irradiated onto an organic film on a second substrate. [Diagram 5] 4 is a diagram showing the direction of light irradiation on an organic film on a first substrate and an organic film on a second substrate, and the alignment direction of liquid crystal molecules in a liquid crystal layer. FIG. [Figure 6] 1 is a schematic diagram of an exposure apparatus and scanning exposure. [Figure 7] FIG. [Figure 8] FIG. 2 is an enlarged view showing a schematic configuration of an overlapping region of a photomask in the first embodiment. [Figure 9] FIG. 13 is a graph showing the results of luminance evaluation of a liquid crystal cell by overlapping exposure. [Figure 10] FIG. 13 is an enlarged view showing a schematic configuration of an overlapping region in another example of the first embodiment. [Figure 11] FIG. 11 is an enlarged view showing a schematic configuration of an overlapping region of a photomask in a second embodiment. [Figure 12] FIG. 13 is an enlarged view showing a schematic configuration of an overlapping region in another example of the second embodiment. [Figure 13] FIG. 13 is an enlarged view showing a schematic configuration of an overlapping region of a photomask in a third embodiment. [Figure 14] FIG. 13 is an enlarged view showing a schematic configuration of an overlapping region in another example of the third embodiment. [Figure 15] FIG. 13 is an enlarged view showing a schematic configuration of an overlapping region of a photomask in a fourth embodiment. [Figure 16] FIG. 1 is an enlarged view showing a schematic configuration of an overlapping region of a conventional photomask. [Figure 17] FIG. 1 is an enlarged view showing a schematic configuration of an overlapping region of a conventional photomask. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, the embodiments will be described with reference to the drawings. In the following embodiments, the same reference numerals are used to designate the same or equivalent parts, and the explanations of the same reference numerals are incorporated herein. In the following explanation, for convenience, up, down, left and right are indicated based on the direction in which the display area of ​​the liquid crystal display device is viewed from the front.

[0018] In this specification, the term "pixel" refers to the smallest unit that expresses the shade (gradation) of each color in a display, and corresponds to the unit that expresses each gradation of R (red), G (green), and B (blue), etc., in a display element using a color filter. Therefore, when the term "pixel" is used, it does not refer to a color display pixel (picture element) that combines R pixels, G pixels, and B pixels, but to each pixel (sub-pixel) of R pixels, G pixels, and B pixels. In other words, in the case of a color liquid crystal display element, one pixel corresponds to one of the colors of the color filter. The term "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.

[0019] "Orientation" refers to the direction on the substrate surface or on a plane parallel to the substrate surface. However, the orientation does not take into account the inclination angle with respect to the normal direction of the substrate surface. Unless otherwise specified, orientations expressed from 0 to 360 degrees are based on the reference orientation (0 degrees) being the azimuth angle to the right in the horizontal direction of the display surface (i.e., the left-right direction of the display surface, also called the "pixel horizontal direction"), and counterclockwise angles are positive angles.

[0020] The "orientation direction of liquid crystal molecules in the liquid crystal layer" refers to the direction of the liquid crystal molecules (more specifically, the liquid crystal molecules that are near the center of the liquid crystal layer in the thickness direction of each pixel) that starts from the long axis end on the substrate (first substrate) side on which the pixel electrodes are arranged and ends at the long axis end on the other substrate (second substrate). Therefore, the "orientation of the long axis direction of the liquid crystal molecules that are near the center of the thickness direction of the liquid crystal layer projected onto the first substrate" refers to the direction of the long axis end on the first substrate side of the liquid crystal molecules that are near the center of the thickness direction of the liquid crystal layer projected onto the first substrate.

[0021] "Tilt orientation of liquid crystal molecules" refers to the orientation of liquid crystal molecules present near the alignment film, which is controlled by the alignment film when no voltage is applied. In this specification, the tilt orientation of liquid crystal molecules is expressed by the orientation starting from the long axis end on the first substrate side and ending at the long axis end on the second substrate side. In this specification, unless a particular viewing direction is indicated, it refers to the orientation when looking from the second substrate side to the first substrate side.

[0022] First Embodiment First, the configuration of a liquid crystal display device 10 manufactured by the manufacturing method of the present disclosure will be described below with reference to the drawings.

[0023] <Liquid crystal display device> The liquid crystal display device 10 is a thin film transistor (TFT) type liquid crystal display device, and has a plurality of pixels arranged in a matrix in a display region. As shown in Fig. 1, the liquid crystal display device 10 includes a pair of substrates consisting of a first substrate 11 and a second substrate 12, and a liquid crystal layer 13 arranged between the first substrate 11 and the second substrate 12. Note that, although the present embodiment describes a case where the present disclosure is applied to a TFT type liquid crystal display device, the present disclosure may also be applied to other driving methods (e.g., a passive matrix method, a plasma address method, etc.).

[0024] The first substrate 11 is a TFT substrate in which pixel electrodes 15 made of a transparent conductor such as ITO (Indium Tin Oxide), TFTs 26 as switching elements, and various wirings such as scanning signal lines 17 and data signal lines 18 are arranged on a transparent substrate 14 made of glass, resin, etc. (see FIG. 2). The second substrate 12 is a counter substrate in which a counter electrode 19 made of a transparent conductor is provided on a transparent substrate 16 made of glass, resin, etc. The counter electrode 19 is a common electrode common to all pixel electrodes 15. The second substrate 12 is a CF substrate provided with a black matrix and a color filter. The color filter has, for example, three colored layers of red (R), green (G), and blue (B). Instead of providing a color filter on the counter substrate, a color filter on array (COA) provided on the pixel substrate may be adopted.

[0025] A liquid crystal alignment film is formed on each of the first substrate 11 and the second substrate 12, which aligns liquid crystal molecules near the substrate surface in a predetermined direction with respect to the substrate surface (i.e., the electrode arrangement surface). The liquid crystal alignment film is a vertical alignment film that aligns liquid crystal molecules substantially vertically when no voltage is applied, and the angle (pretilt angle) 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, as the liquid crystal alignment films, a first alignment film 22 formed on the electrode arrangement surface of the first substrate 11 and a second alignment film 23 formed on the electrode arrangement surface of the second substrate 12.

[0026] At least one of the first alignment film 22 and the second alignment film 23 is a photo-alignment film, and 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 with a liquid crystal alignment agent. The liquid crystal display device 10 of this embodiment is alignment-divided, and has two or more regions with different alignment directions within a pixel 30. This compensates for the viewing angle characteristics of the liquid crystal display device 10.

[0027] As a liquid crystal alignment agent for forming a photo-alignment film, a polymer composition containing a polymer having a photo-alignment structure is preferably used. The polymer having a photo-alignment structure is not particularly limited, and a polymer known as a polymer component of a photo-alignment film can be appropriately used. Specific examples of the photo-alignment structure include a cinnamic acid structure, an azobenzene structure, a coumarin structure, a chalcone structure, and a cyclobutane structure. Examples of the main chain of the polymer having a photo-alignment structure include polyamic acid, polyimide, polyorganosiloxane, polyamic acid ester, polyamide, polyenamine, (meth)acrylic polymer, styrene polymer, maleimide polymer, and styrene-maleimide polymer. Note that "(meth)acrylic" is a term that includes "acrylic" and "methacrylic".

[0028] The liquid crystal alignment agent for forming the first alignment film 22 and the second alignment film 23 may contain only one type of polymer as a polymer component, or may contain two or more types of polymers. The liquid crystal alignment agent is usually a liquid composition in which the polymer component is dissolved or dispersed in one or more types of solvents. In addition to the polymer component, the liquid crystal alignment agent may further contain one or more types of additives such as a crosslinking agent, an adhesion assistant, an ultraviolet absorber, and a photosensitizer.

[0029] The first substrate 11 and the second substrate 12 are arranged with a predetermined gap (cell gap) between them via a spacer 24 so that the electrode arrangement surface of the first substrate 11 and the electrode arrangement surface of the second substrate 12 face each other. Although FIG. 1 shows a case where the spacer 24 is a columnar spacer, it may be another spacer for liquid crystal display devices such as a bead spacer. The first substrate 11 and the second substrate 12 arranged opposite each other are bonded together at their peripheries via a seal member 25. A liquid crystal composition is filled in the space surrounded by the first substrate 11, the second substrate 12, and the seal 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 anisotropy.

[0030] The liquid crystal may be a known liquid crystal material having negative dielectric anisotropy. The refractive index anisotropy Δn of the liquid crystal is appropriately set so that the retardation (d·Δn), which is expressed as the product of the refractive index anisotropy Δn of the liquid crystal and the thickness d of the liquid crystal layer 13, is 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 to 5 μm.

[0031] A pair of polarizing plates are disposed on the outer sides of the first substrate 11 and the second substrate 12. The pair of polarizing plates is composed of a first polarizing plate 27 provided on the outer surface of the first substrate 11 and a second polarizing plate 28 provided 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 disposed so that their polarization axes intersect (more specifically, are perpendicular to each other). A terminal area (not shown) is provided on the outer edge of the first substrate 11, and a driver IC or the like for driving the liquid crystal is connected to the terminal area to drive the liquid crystal display device 10.

[0032] In this embodiment, a vertical alignment type liquid crystal display device is described, but the present disclosure may be applied to a horizontal alignment type liquid crystal display device. When applied to a horizontal alignment type liquid crystal display device, liquid crystal molecules in the liquid crystal layer 13 may be liquid crystal having positive dielectric anisotropy, and a horizontal alignment type liquid crystal alignment film may be used instead of a vertical alignment film as the liquid crystal alignment film.

[0033] (Pixel structure) Next, the pixel structure and alignment division of the liquid crystal display device 10 will be described with reference to Figs. 3 to 5. Arrows P1 to P4 in Figs. 3 to 5 indicate the direction of light irradiation to the photosensitive organic film 29 formed by a liquid crystal alignment agent. In Fig. 5, the cone with reference numeral 35 represents a liquid crystal molecule. In Fig. 5, the orientation of the cone 35 indicates the alignment direction of the liquid crystal molecules in the liquid crystal layer 13. Here, the direction from the bottom surface of the cone 35 to the apex is defined as the direction toward the first substrate 11. In the following description, the direction along the short side direction of the pixel 30 when the first substrate 11 is viewed in plan is defined as the X-axis direction, and the direction along the long side direction of the pixel 30 is defined as the Y-axis direction. In this embodiment, the X-axis direction is the direction along the horizontal direction of the display screen.

[0034] As shown in Figures 3 to 5, each pixel 30 has two square half pixels 30a (i.e., half of one pixel) arranged side by side 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 Figures 3 to 5). In this embodiment, the organic films 29 formed on the first substrate 11 and the second substrate 12 are exposed to light a plurality of times from different directions, thereby forming four liquid crystal domains (first domain 31 to fourth domain 34) in the half pixel 30a (see Figures 3 to 5).

[0035] Specifically, regarding the exposure of each substrate, as shown in Fig. 3, the organic film 29 formed on the first substrate 11 is irradiated with light from a direction P1 out of two regions obtained by dividing a half pixel 30a in the Y-axis direction, and the other region is irradiated with light from a direction P2 that is anti-parallel to the direction P1. As shown in Fig. 4, regarding the organic film 29 formed on the second substrate 12, as shown in Fig. 4, the organic film 29 formed on the first substrate 11 is irradiated with light from a direction P3 out of two regions obtained by dividing a half pixel 30a in the X-axis direction, and the other region is irradiated with light from a direction P4 that is anti-parallel to the direction P3. The irradiation directions of light on the organic film 29 formed on the first substrate 11 and the organic film 29 formed on the second substrate 12 are set to be different from each other by approximately 90° when the first substrate 11 and the second substrate 12 are bonded together (see Fig. 5). That is, in each liquid crystal domain, the tilt orientation of the liquid crystal molecules existing near the first alignment film 22 and the tilt orientation of the liquid crystal molecules existing near the second alignment film 23 differ from each other by approximately 90°. As a result, the liquid crystal molecules contained in the liquid crystal layer 13 are twisted by approximately 90° between the pair of substrates when a voltage is applied, and are vertically aligned when no voltage is applied. When a voltage is applied, the orientations of the major axis directions of the liquid crystal molecules existing near the center in the thickness direction of the liquid crystal layer 13 projected onto the first substrate 11 are approximately 225°, approximately 135°, approximately 45°, and approximately 315° in the first to fourth domains 31 to 34, respectively (see FIG. 5).

[0036] The configuration of the pixel 30 is not limited to the configuration shown in Figs. 3 to 5. For example, one pixel 30 may be configured by arranging half pixels 30a in the horizontal direction of the display screen. The number of liquid crystal domains in the half pixel 30a is not particularly limited, and may be, for example, two. In addition, one pixel is not limited to being divided into eight regions, and may be divided into, for example, four regions. The arrangement of the pixel 30 is not limited to a matrix. The liquid crystal display device 10 has the pixels 30 shown in Figs. 3 to 5, and one pixel 30 is divided into a total of eight regions. However, since there are four orientation directions of the liquid crystal molecules, the liquid crystal display device 10 is in a four-domain RTN mode or 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, by irradiating light a total of four times.

[0037] <Method of Manufacturing Liquid Crystal Display Device> 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. Film formation process: A process of applying a liquid crystal alignment agent to a substrate and forming a photosensitive organic film (organic film 29) Exposure step: a step of exposing the organic film 29 to light through a photomask while moving the substrate on which the organic film 29 is formed relative to a light source. Each step will be described below.

[0038] (film formation process) First, the first substrate 11 and the second substrate 12 are prepared. Then, a liquid crystal alignment agent is applied onto each electrode arrangement surface of the first substrate 11 and the second substrate 12 to form a coating film on the substrate. In the film formation 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. The liquid crystal alignment agent is preferably applied to the substrate by offset printing, flexographic printing, spin coating, roll coater, or inkjet printing.

[0039] After the liquid crystal alignment agent is applied, preliminary heating (pre-baking) is preferably performed for the purpose of preventing dripping of the applied liquid crystal alignment agent. The pre-baking temperature is preferably 30 to 200°C, and the pre-baking time is preferably 0.25 to 10 minutes. Thereafter, baking (post-baking) is performed for the purpose of removing the solvent, etc. The baking temperature (post-baking temperature) is preferably 80 to 300°C, and the post-baking time is preferably 5 to 200 minutes. The thickness of the coating film formed is, for example, 0.001 to 1 μm.

[0040] (Exposure process) Subsequently, the organic film 29 formed in the film formation process is subjected to a photo-alignment treatment to provide the organic film 29 with a desired pretilt angle. In the case of a vertical alignment film, the pretilt angle is, for example, 85 to 89.9°. In this embodiment, the organic film 29 formed on each of the substrate surfaces of the first substrate 11 and the second substrate 12 is irradiated with polarized radiation (linearly polarized radiation) from an oblique direction to the substrate surface through a photomask 40 (see FIG. 6). The radiation irradiated to the organic film 29 can be, for example, ultraviolet light containing light with a wavelength of 150 to 800 nm and visible light. Preferably, it is ultraviolet light containing light with a wavelength of 200 to 400 nm.

[0041] Examples of light sources used include low-pressure mercury lamps, high-pressure mercury lamps, deuterium lamps, metal halide lamps, argon resonance lamps, xenon lamps, excimer lasers, etc. The radiation dose is preferably 50 to 50,000 J / m 2 and more preferably 100 to 2,000 J / m 2 The angle formed by the radiation irradiation direction with respect to the substrate surface is, for example, 30° or more and less than 90°. After the light irradiation, the substrate surface may be washed with water, an organic solvent (e.g., methanol, isopropyl alcohol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, etc.), or a mixture thereof, or the substrate may be heated.

[0042] The photo-alignment treatment is preferably performed by scanning exposure in which the organic film 29 is irradiated with radiation while the substrate is moved in a predetermined direction relative to the light source, or while the light source is moved in a predetermined direction relative to the substrate. In this embodiment, the organic film 29 formed in the film formation process is exposed to light multiple times to form multiple liquid crystal domains in which the orientations of the long axis directions of the liquid crystal molecules present near the center in the thickness direction of the liquid crystal layer 13 projected onto the first substrate 11 are different from each other. For example, in the pixel shown in Figures 3 to 5, one half pixel region is divided into four regions in which the alignment orientations of the liquid crystal molecules are different from each other.

[0043] An example of the exposure apparatus 50 and scanning exposure used in this embodiment will be described with reference to Fig. 6. In Fig. 6, an arrow with a symbol W indicates the moving direction (scanning direction) of the substrate 38 relative to the light source 36, and an arrow with a symbol M indicates the transmission axis direction of the polarizer 37. The scanning direction W corresponds to the "predetermined moving direction".

[0044] 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 disposed above the substrate 38 with a predetermined distance (proximity gap), and the light source 36 is disposed above the photomask 40. The photomask 40 is provided with a number of slits 61. For convenience, only one slit 61 is shown in FIG. 6. The slit 61 corresponds to a "light-transmitting section." In the exposure device 50, the organic film 29 is scanned and exposed through the photomask 40 by irradiating the substrate 38 with light from the light source 36 while the scanning unit 51 moves the substrate 38 in the scanning direction W relative to the light source 36. The irradiated light U from the light source 36 passes through the polarizer 37, and the transmitted light vibrating in the transmission axis direction passes through the slits 61 of the photomask 40 and is irradiated from an oblique direction to the organic film 29 formed on the substrate 38.

[0045] The substrate 38 may be either the first substrate 11 or the second substrate 12. In this embodiment, the exposure device 50 irradiates linearly polarized light onto the organic film 29 formed on each of the first substrate 11 and the second substrate 12. By exposing the organic film 29 to light, a tilt orientation (direction S1 in FIG. 6) in the same direction along the scanning direction W is imparted to the organic film 29. Note that instead of a configuration in which the scanning unit 51 moves the substrate 38 relative to the light source 36, a configuration in which the light source 36 moves relative to the substrate 38 may be employed.

[0046] Here, in the manufacturing process of the liquid crystal display device 10, from the viewpoint of efficiently producing the large-screen size liquid crystal display device 10, exposure may be performed on the organic film 29 formed on a large (e.g., G8 size or G10 size) mother substrate. In the example shown in Fig. 7, the substrate 38 includes eight substrates 38a (first substrates 11 or second substrates 12). It is not realistic from the viewpoint of facilities and costs to expose such a large substrate 38 at once in a single exposure using a large exposure device 50 or a large photomask.

[0047] Therefore, in this embodiment, a relatively small photomask 40 is used for the substrate 38, a part of the organic film 29 is exposed once through the photomask 40, and at least a part of the remaining part is exposed once through the photomask 40. If the relatively small photomasks 40 are simply joined together for the substrate 38 and the entire surface of the organic film 29 is exposed once, the seams between adjacent exposed regions are likely to appear as luminance differences due to differences in exposure conditions (for example, differences in illuminance between exposed regions, mask position shifts, etc.), and the luminance differences may be visually recognized by an observer as display unevenness. Note that even if there is a slight difference in exposure conditions, if the luminance changes discontinuously, the discontinuous luminance changes are likely to be visually recognized by the human eye as display unevenness. On the other hand, by providing a portion that is exposed overlappingly between adjacent exposed regions, it is possible to suppress a sudden change in luminance at the seams of the photomask 40, thereby reducing the occurrence of display unevenness.

[0048] In this embodiment, in order to improve production efficiency, a plurality of photomasks 40 are used to expose the substrate surface. Specifically, as shown in FIG. 7, the plurality of photomasks 40 are arranged in a cross direction V that is a direction intersecting (preferably perpendicular to) the scanning direction W and that is a direction along the substrate surface. By linearly moving the substrate 38 in the scanning direction W relative to the plurality of photomasks 40, 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 with respect to the light source 36. At this time, exposure is performed once on a portion of the organic film 29, and overlapping exposure is performed on the remaining region.

[0049] The arrangement of the multiple photomasks 40 will be described with reference to FIG. 6 and FIG. 7 as appropriate. The exposure device 50 is provided with an exposure unit 52 in which the light source 36 and the photomask 40 are integrated. The exposure unit 52 includes, as the photomask 40, a first photomask 41 arranged on the same line extending in the cross direction V, and a second photomask 42 arranged on the same line extending in the cross direction V and behind the first photomask 41 as viewed from the substrate 38 in the scanning direction W. The first photomask 41 and the second photomask 42 are adjacent to each other in the cross direction V, and are arranged such that adjacent photomasks 40 partially overlap each other as viewed in the scanning direction W. The exposure unit 52 is provided with a number of light sources 36 (i.e., a plurality of light sources) corresponding to the number of photomasks 40, and each light source 36 and each photomask 40 are integrated.

[0050] In the exposure device 50, the substrate 38 is moved relative to the exposure unit 52 by a scanning unit 51 moving the substrate 38 with respect to the exposure unit 52 fixed at a predetermined position. As a result, the organic film 29 on the substrate 38 has a non-overlapping region 29a where exposure is performed once through the first photomask 41 or the second photomask 42, and an overlapping region 29b (hatched portion in FIG. 7) where overlapping exposure is performed through the first photomask 41 and the second photomask 42, as shown in FIG. 7. The overlapping region 29b is irradiated with light through a joint 43 between the first photomask 41 and the second photomask 42.

[0051] In order to obtain a liquid crystal display device 10 with multiple alignments, the organic film 29 is exposed multiple times from different directions. For example, the half pixel 30a having four liquid crystal domains 31 to 35 shown in FIGS. 3 to 5 can be obtained by performing two scan exposures on each of the organic film 29 formed on the first substrate 11 and the organic film 29 formed on the second substrate 12. Specifically, when exposing the substrate 38 for obtaining the first substrate 11, the slit 61 of the photomask 40 is first aligned with the half pixel 30a (more specifically, half of the region obtained by dividing the half pixel 30a in the Y-axis direction). Next, while moving the substrate 38 along the Y-axis direction, polarized ultraviolet light is irradiated obliquely onto the substrate surface through the first photomask 41 and the second photomask 42 (first scan). This first scan imparts liquid crystal alignment ability to the half region obtained by dividing the half pixel 30a in the Y-axis direction. At this time, for the pixels 30 included in the overlap region 29b, exposure through the first photomask 41 and exposure through the second photomask 42 are overlapped. The total amount of exposure for the pixels 30 included in the overlap region 29b (i.e., the total amount of exposure through the first photomask 41 and the second photomask 42) is, for example, 80 to 100% of the amount of exposure for the pixels 30 included in the non-overlap region 29a. In this embodiment, the total amount of exposure for the pixels 30 included in the overlap region 29b is set to be equal to the amount of exposure for the pixels 30 included in the non-overlap region 29a (approximately 100%).

[0052] Next, the substrate 38 exposed by the first scan is rotated 180° in-plane, and the unexposed region of the half pixel 30a that is not exposed by the first scan is aligned with the slit 61 of the photomask 40. Since the half pixel 30a is square, the length of the half pixel 30a in the X-axis direction is the same as the length of the half pixel 30a in the Y-axis direction. Thereafter, as in the first scan, the substrate surface is irradiated with polarized ultraviolet light from an oblique direction through the first photomask 41 and the second photomask 42 while moving the substrate 38 in the Y-axis direction (second scan). As a result, as shown in FIG. 3, a liquid crystal alignment film (first alignment film 22) is formed on the first substrate 11 in two regions obtained by dividing the half pixel 30a in the Y-axis direction, in which the tilt orientations of the liquid crystal molecules are antiparallel to each other in the Y-axis direction.

[0053] In the above, the same exposure unit 52 is used for 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 the unexposed area is then exposed by the second scan. However, the scanning exposure method is not limited to the above. For example, the first scan and the second scan may be performed by different exposure units. Specifically, an exposure unit (first exposure unit) for the first scan in which the light irradiation direction is a predetermined direction, and an exposure unit (second exposure unit) for the second scan in which the 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 first scan, the second exposure unit irradiates the unexposed area of ​​the half pixel 30a that is not exposed by the first scan with polarized ultraviolet light from an oblique direction relative to the substrate surface (second scan). This method requires the arrangement of many scanning light sources and photomasks, but the time required for exposure processing can be shortened.

[0054] When exposing the substrate 38 corresponding to the second substrate 12, the exposure is basically the same as that of the first substrate 11, except that the scanning direction is the X-axis direction. By performing two scanning exposures on the substrate 38 corresponding to the second substrate 12, as shown in FIG. 4, a liquid crystal alignment film (second alignment film 23) is formed on the second substrate 12 in two regions obtained by dividing the half pixel 30a in the X-axis direction into two, in which the tilt orientations of the liquid crystal molecules are antiparallel to each other in the X-axis direction. Thereafter, the first substrate 11 and the second substrate 12 are arranged with a predetermined gap (cell gap) so 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 obtaining a pixel 30 having four liquid crystal domains, as shown in FIG. 5.

[0055] <Photomask> Next, the configuration of the photomask 40 (particularly the mask pattern) will be described in detail. The photomask 40 includes a plurality of slits 61 and light-shielding portions 62 provided between the slits 61, and the slits 61 and the light-shielding portions 62 are arranged alternately. As shown in FIG. 7 and FIG. 8, each of the first photomask 41 and the second photomask 42 has a non-overlapping region 45 where the first photomask 41 and the second photomask 42 do not overlap as viewed in the scanning direction W, and an overlapping region 46 where the first photomask 41 and the second photomask 42 overlap as viewed in the scanning direction W. Note that FIG. 8 shows the first photomask 41 and the second photomask 42 in a portion corresponding to the region G in FIG. 7. The photomask pattern in the portion other than the portion corresponding to the region G has the same photomask pattern as the portion corresponding to the region G.

[0056] The non-overlapping region 45 is a region in the photomask 40 corresponding to a portion of the organic film 29 to be exposed once. As shown in FIG. 8, the non-overlapping region 45 is provided with a plurality of slits 61a having the same opening area, and light-shielding portions 62a are arranged between the slits 61a. The slits 61a have a rectangular shape (more specifically, a rectangular shape) extending in the scanning direction W, and are arranged at intervals equal to the pixel pitch Px (i.e., at equal intervals) in the direction along the intersecting direction V. The slit width Lx, which is the length of the slits 61a in the intersecting direction V, is, for example, approximately half the pixel pitch Px ±α (μm). The length Ly of the slits 61a in the scanning direction W is a predetermined reference length Lyc, for example, about 40 mm.

[0057] The overlapping region 46 is a region corresponding to a portion of the photomask 40 where the organic film 29 is subjected to overlapping exposure. In the overlapping region 46, as shown in FIG. 8, a plurality of slits 61b having different opening areas are provided, and light-shielding portions 62b are arranged between the slits 61b. The slits 61b are rectangular and are arranged in the direction along the cross direction V at the same intervals as the pixel pitch Px (i.e., at equal intervals). Note that the "plurality of slits with different opening areas" is not limited to a configuration that does not include slits with the same opening area, and may include slits 61b having the same opening area as long as the opening areas of at least some of the slits 61b are different from each other. At least some of the slits 61 (slits 61b) arranged in the overlapping region 46 have smaller opening areas than the slits 61 (slits 61a) arranged in the non-overlapping region 45. The opening area of ​​the slits 61b can be made variable by adjusting the length Ly, for example.

[0058] The first photomask 41 and the second photomask 42 may have the overlap region 46 only at one end, or may have the overlap region 46 at both ends in the cross direction V, depending on the position in the cross direction V with respect to the substrate 38. Of the photomasks 40, the photomask 40 arranged on the outer edge of the substrate 38 in the cross direction V may have the overlap region 46 at at least one mask end. Also, the photomask 40 arranged in the center of the substrate 38 in the cross direction V may have the overlap region 46 at each of the two ends in the cross direction V, and may form a joint portion 43 between adjacent photomasks 40.

[0059] Here, in the overlap region 29b where light is irradiated through the joint 43, a difference in luminance is likely to occur between the overlap region 29b and the non-overlap region 29a due to overlapping exposure. Regarding the change in luminance of the overlap region 29b relative to the non-overlap region 29a, the present inventors prepared an evaluation cell produced by a single exposure of the organic film 29 and an evaluation cell produced by overlapping exposure, and compared the luminance of the evaluation cells. As a result, they found that the change in luminance of the overlap region 29b is greater than that of the non-overlap region 29a when the exposure amounts of each exposure in the overlapping exposure are similar.

[0060] FIG. 9 shows the results of evaluating the luminance of an evaluation cell prepared by one exposure to the organic film 29 and an evaluation cell prepared by overlapping exposure. In the luminance evaluation of FIG. 9, an evaluation cell was prepared and evaluated by the following method. First, a transparent electrode was formed on a glass substrate, a liquid crystal alignment agent was applied to the transparent electrode, and then a heat treatment was performed to form a photosensitive organic film (organic film 29). Next, the photosensitive organic film formed on the glass substrate was irradiated with polarized ultraviolet light from an oblique direction relative to the substrate surface to impart liquid crystal alignment in one direction to form a photo-alignment film. The same operation was performed to prepare two glass substrates on which a photo-alignment film was formed. The two substrates were bonded together via a spacer and a sealant, and a liquid crystal material having negative dielectric anisotropy was further injected between the substrates to prepare a vertically aligned evaluation cell. This evaluation cell was sandwiched between polarizing plates, and the amount of light transmitted through the evaluation cell was measured with a voltage of 2.3 V applied between the transparent electrodes.

[0061] A total of four cells were prepared as evaluation cells by applying any one of the following conditions (1) to (4) in which the number of times and the amount of exposure of the organic film 29 were different. The light was irradiated in the same direction in all cases. (1) Irradiate the substrate surface once at an angle with polarized ultraviolet light at a standard exposure dose. (2) Irradiate the substrate surface once from an oblique direction with polarized ultraviolet light with an exposure amount of 80% of the reference exposure amount, and then irradiate the substrate surface once from an oblique direction with polarized ultraviolet light with an exposure amount of 20% of the reference exposure amount. (3) Irradiate the substrate surface once from an oblique direction with polarized ultraviolet light with an exposure amount of 50% of the reference exposure amount, and then irradiate the substrate surface once from an oblique direction with polarized ultraviolet light with an exposure amount of 50% of the reference exposure amount. (4) Irradiate the substrate surface once from an oblique direction with polarized ultraviolet light with an exposure amount of 20% of the reference exposure amount, and then irradiate the substrate surface once from an oblique direction with polarized ultraviolet light with an exposure amount of 80% of the reference exposure amount.

[0062] Regarding the evaluation results, the amount of transmitted light of the evaluation cell prepared by a single exposure at the reference exposure amount (condition (1)) was set to 100, and the amount of transmitted light of each evaluation cell was expressed as an index, which was 100.6% under condition (2), 102.0% under condition (3), and 100.6% under condition (4) (see FIG. 9). From the results of this luminance evaluation, it was found that when multiple exposure was performed under condition (3), the luminance was higher than when multiple exposure was performed under condition (2) or condition (4), and the change in luminance due to a single exposure was noticeable.

[0063] The reason why the brightness change occurs as described above is not yet clear, but it is assumed that the reaction (specifically, a reaction that makes the pretilt angle of the liquid crystal molecules of the evaluation cell smaller) occurs on the surface of the organic film 29 in the overlapping region 29b where overlapping exposure is performed, which is different from that in the non-overlapping region 29a where the exposure does not overlap. More specifically, the reaction on the film surface caused by the oblique irradiation of polarized ultraviolet light is considered to be related to a chemical reaction that is proportional to the amount of exposure during the light irradiation period and a chemical reaction that occurs due to relaxation after the end of the light irradiation and is not simply proportional to the amount of exposure, in both the single exposure and the multiple exposures. Here, in the case of a single exposure, the reaction that occurs due to relaxation after the end of the light irradiation occurs only once, whereas in the case of multiple exposures, the reaction that occurs due to relaxation after the end of the light irradiation occurs multiple times, and further, when exposure is performed multiple times with polarized ultraviolet light exceeding a certain amount of exposure, the influence of each reaction that occurs due to relaxation after the end of each light irradiation is considered to be large. As a result, when multiple exposures are performed with polarized ultraviolet light exceeding a certain exposure amount, a change in the pretilt angle is brought about in the photo-alignment film that exceeds the total amount of each exposure, which appears as a change in luminance. Note that this is merely a guess and does not limit the present invention.

[0064] Based on the above findings, in this embodiment, the slits 61b provided in the overlapping region 46 of the photomask 40 are the first slits 63 having an opening area of ​​75% to 100% of the opening area of ​​the slits 61a arranged in the non-overlapping region 45 (hereinafter also referred to as the "reference area Sc"), or the second slits 64 having an opening area of ​​more than 0% to 25% of the reference area Sc. This avoids a large change in luminance due to the exposure amounts being close to each other in the overlapping region 29b, and suppresses a decrease in display quality due to the overlapping region 29b becoming locally bright. In addition, it is also significant that the slits 61b in the overlapping region 46 are made into a photomask pattern consisting of the first slits 63 and the second slits 64, which is a simple method, and suppresses the influence of the material of the liquid crystal alignment film and the variation in the illuminance of the light source 36 while suppressing the luminance change in the joint portion 43.

[0065] The opening area of ​​the first slit 63 may be within a range of 75% to 100%. From the viewpoint of sufficiently suppressing localized brightness on the display screen corresponding to the overlap region 29b, the opening area of ​​the first slit 63 is preferably 80% or more. Moreover, from the viewpoint of suppressing unevenness in brightness over the entire overlap region 29b, the opening area of ​​the first slit 63 is preferably less than 100%, more preferably 99% or less, and even more preferably 98% or less.

[0066] The opening area of ​​the second slit 64 may be within a range of more than 0% and not more than 25%. From the viewpoint of suppressing the unevenness of the brightness over the entire overlap region 29b, the opening area of ​​the second slit 64 is preferably 1% or more, more preferably 2% or more. Also, the opening area of ​​the second slit 64 is preferably 20% or less. Note that the multiple first slits 63 arranged in the overlap region 46 may all have the same opening area, or at least some of them may have different opening areas. Similarly, the multiple second slits 64 arranged in the overlap region 46 may all have the same opening area, or at least some of them may have different opening areas.

[0067] 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 region 45, and is, for example, approximately half 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 opening area of ​​the slit 61 becomes smaller as the length Ly becomes shorter.

[0068] The arrangement of the slits 61b in the overlapping region 46 will be described in more detail with reference to Fig. 8. As shown in Fig. 8, 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 intersecting direction V. Furthermore, when viewed in the scanning direction W, the first photomask 41 and the second photomask 42 are positioned such that the first slits 63 arranged in the overlapping region 46 of one 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 (on the straight line Ey in Fig. 8).

[0069] In the example shown in FIG. 8, the first slit 63 has a length Ly of 75% of the reference length Lyc and an opening area of ​​75% of the reference area Sc. The second slit 64 has a length Ly of 25% of the reference length Lyc and an opening area of ​​25% of the reference area Sc. The sum of the opening areas 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, the second slit 64 is arranged in the first photomask 41 and the first slit 63 is arranged in the second photomask 42 at the 10th position in the direction from the center line Ec toward the non-overlapping area 45 of the first photomask 41, based on the center line Ec of the overlapping area 46 extending in the scanning direction W.

[0070] In the overlapping region 46 of each 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 respect to the center line Ec of the overlapping region 46 as an axis, and the first slit 63 is arranged at a position symmetrical to the second slit 64. By arranging in this manner, it is possible to suppress the bias of the slit opening area at the joint portion 43 between the first photomask 41 and the second photomask 42 by a simple method. As a result, it is possible to suppress the occurrence of unevenness in the luminance change over the entire cross direction V at the joint portion 43, and thus it is possible to suppress the display unevenness caused by overlapping exposure. In the example shown in FIG. 8, 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 portion 44. Further, the first slit 63 is disposed at the 15th position from the center line Ec toward the non-overlapping region 45, and the second slit 64 is disposed at the 15th position from the center line Ec toward the mask end 44.

[0071] In each overlapping region 46, the slits 61b (i.e., the first slits 63 and the second slits 64) are arranged side by side so that the sum ΣS of the opening areas of the slits 61b included in the region of a 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 slits 63 and the second slits 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. This makes it possible to continuously change the luminance over the entire overlapping region 29b, and to make the luminance change in the transition portion from the overlapping region 29b to the non-overlapping region 29a smoother. As a result, it is possible to more effectively prevent the boundary between the overlapping region 29b and the non-overlapping region 29a from being visually recognized by the observer on the display screen. The method of changing the sum ΣS of the opening areas is not particularly limited, and for example, a linear change, a trigonometric change, or the like may be adopted.

[0072] 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, in the example shown in FIG. 8, when the number of pixels Nx is 5, the sum ΣS of the opening areas of the slits included in the region of the predetermined length Hx (region Hx1 in FIG. 8) at the end 44 of 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 sum ΣS of the opening areas of the slits included in the region of the predetermined length Hx (region Hx2 in FIG. 8) at the center of the overlap region 46 of the first photomask 41 is "(reference area Sc×0.75×2)+(reference area Sc×0.25×3)=reference area Sc×2.25". The sum ΣS of the opening areas of the slits included in the region of a predetermined length Hx (region Hx3 in FIG. 8) in the overlap region 46 of the first photomask 41 adjacent to the non-overlapping region 45 is "(reference area Sc×0.75×4)+(reference area Sc×0.25×1)=reference area Sc×3.25". That is, the overlap region 46 of the first photomask 41 shows an increasing trend of "1.75→2.25→3.25" from the mask end 44 toward the non-overlapping region 45. The same is true for the overlap region 46 of the second photomask 42.

[0073] In each overlapping region 46, the sum of the opening areas ΣS tends to increase from the mask end 44 toward the non-overlapping region 45 due to the discrete density of the 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 the example shown in FIG. 8, the number of the first slits 63 included in the region Hx1 is "1", the number of the first slits 63 included in the region Hx2 is "2", and the number of the first slits 63 included in the region Hx3 is "4", and the number of the first slits 63 included per unit area (i.e., the frequency of the first slits 63) increases from the mask end 44 toward the non-overlapping region 45. Due to the discrete density of the first slits 63, the change in the opening area in the cross direction V can be made smoother by a simple method of designing the arrangement of the slits 61b. As a result, the luminance unevenness on the display screen caused by overlapping exposure can be suppressed without relying on a complicated method.

[0074] 8, in each of the overlapping regions 46 of the first photomask 41 and the second photomask 42, the second slits 64 are arranged alone at the boundary 47 with the non-overlapping region 45, and the first slits 63 are arranged alone at the mask end 44. Even when the second slits 64 are arranged at the boundary 47, if the second slits 64 are arranged alone, it is possible to suppress a sudden change in the slit opening area at the boundary 47. Therefore, even in this case, it is possible to suppress a sudden change in luminance between the overlapping region 29b and the non-overlapping region 29a, and to suppress the occurrence of display unevenness at the joint 43.

[0075] In the present embodiment described above, in consideration of the fact that the luminance change becomes large in the overlap region 29b when the exposure amounts of each exposure are similar in the overlapping exposure, the slits 61b arranged in the overlap region 46 of the photomask 40 are the first slits 63 having an opening area of ​​75% to 100% of the reference area Sc, or the second slits 64 having an opening area of ​​more than 0% to 25% of the reference area Sc. This makes it possible to prevent the overlap region 29b from becoming locally bright due to the exposure amounts of each exposure being similar in the overlap region 29b, and as a result, it is possible to prevent display defects in the liquid crystal display device 10.

[0076] In this embodiment, when viewed in the scanning direction W, the first slit 63 arranged in the overlapping region 46 of one of the first photomask 41 and the second photomask 42 and the second slit 64 arranged in the overlapping region 46 of the other photomask are arranged on a straight line Ey. This makes it possible to suppress the occurrence of uneven brightness caused by uneven exposure throughout the entire overlapping region 29b, and as a result, it is possible to suppress the occurrence of display unevenness throughout the entire overlapping region 29b. In addition, it is possible to smooth the change in the exposure amount at the boundary between the non-overlapping region 29a and the overlapping region 29b, and it is possible to suppress the joint portion 43 from being visible on the display screen.

[0077] 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 sum of the opening areas of the first slit 63 and the second slit 64 arranged on the straight line Ey can be made equal to the reference area Sc. This makes it possible to smooth the change in the exposure amount at the boundary between the non-overlap region 29a and the overlap region 29b, and effectively prevents the joint portion 43 from being visible on the display screen.

[0078] Furthermore, in this embodiment, the slits 61b are arranged in the overlapping regions 46 of the first photomask 41 and the second photomask 42 so that the sum of the opening areas ΣS shows an increasing tendency from the mask end portion 44 toward the non-overlapping region 45 due to the discrete density of the first slits 63. Therefore, while obtaining the effect of suppressing an increase in luminance by the arrangement of the first slits 63 and the second slits 64, it is possible to make the change in the opening area of ​​the slits 61b smooth over the boundary portion between the seam portion 43 and the non-overlapping region 45 and over the entire seam portion 43.

[0079] The present embodiment is not limited to the above-described embodiment, and may be implemented in the following manner, for example.

[0080] 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 may be 75% or more and 100% or less of the reference area Sc, and the opening area of ​​the second slit 64 may be more than 0% and 25% or less of the reference area Sc. For example, as shown in Fig. 10, 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. Considering ease of design and light transmission limits, the opening area of ​​the second slit 64 is preferably 1% or more and 25% or less of the reference area Sc, and more preferably 2% or more and 25% or less.

[0081] In the above embodiment, all the first slits 63 have the same opening area, and all the second slits 64 have the same opening area, but as long as the opening area of ​​the first slits 63 is 75% or more and 100% or less of the reference area Sc, and the opening area of ​​the second slits 64 is more than 0% and 25% or less of the reference area Sc, the first slits 63 and the second slits 64 may each include slits with different opening areas. For example, the first slits 63 may include a slit whose opening area is 80% of the reference area Sc and a slit whose opening area is 90% of the reference area Sc. Similarly, the second slits 64 may include a slit whose opening area is 20% of the reference area Sc and a slit whose opening area is 10% of the reference area Sc.

[0082] In the above embodiment, in the overlapping region 46 of each 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 set to be equal to the reference area Sc (i.e., 100% of the reference area Sc), but this is not limited to the above configuration. For example, the total opening area of ​​the two slits arranged on the straight line Ey may be set to, for example, 80 to 99% of the reference area Sc. Also, instead of the configuration in which the total opening area of ​​the two slits arranged on the straight line Ey is set to be the same throughout the joint portion 43, the total opening area of ​​the two slits arranged on the straight line Ey may be made variable in the joint portion 43. For example, the total opening area of ​​the two slits arranged on the straight line Ey may be linearly or trigonometrically decreased from the end portion to the center portion of the joint portion 43.

[0083] In the above embodiment, the second slit 64 is disposed at a position symmetrical to the first slit 63 with respect to the center line Ec, and the first slit 63 is disposed at a position symmetrical to the second slit 64, but this is not limited thereto, and the first slit 63 may be disposed at a position symmetrical to the first slit 63 with respect to the center line Ec. Moreover, the second slit 64 may be disposed at a position symmetrical to the second slit 64 with respect to the center line Ec.

[0084] Second Embodiment Next, a second embodiment of the manufacturing method of the present disclosure will be described. In the second embodiment, the arrangement (photomask pattern) of the slits 61 in the joint portion 43 of the photomask 40 is different from that of the first embodiment. In the following description, the description of the same configuration as the first embodiment will be omitted, and the differences from the first embodiment will be mainly described.

[0085] FIG. 11 shows the configuration of the photomask 40 in the second embodiment. 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. The second slit 64 is arranged in the second section F2, and the first slit 63 is not arranged. In the example shown in FIG. 11, of the two sections divided by the center line Ec, the region including the boundary portion 47 with the non-overlapping region 45 is the first section F1, and the region including the mask end 44 is the second section F2. By arranging the first section F1 formed by the first slit 63 at the boundary portion with the non-overlapping region 45 at the joint portion 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 region 29a and the overlapping region 29b. This effectively prevents the luminance change in the overlap region 29b from being visually recognized as display unevenness.

[0086] A plurality of first slits 63 are arranged in the first section F1. It is preferable that the opening area of ​​each of the plurality of first slits 63 arranged in the first section F1 is smaller in a direction away from the non-overlapping region 45. This allows the exposure amount at the boundary between the non-overlapping region 29a and the overlapping region 29b to be continuously changed along the cross direction V, and the luminance change in the overlapping region 29b can be more effectively suppressed. In the example shown in FIG. 11, in the first section F1, the opening area of ​​the first slits 63 is gradually decreased (preferably monotonically decreased) from 99% to 75% of the reference area Sc by changing the length Ly of each slit. Moreover, the first first slit 63 from the center line Ec has a length Ly that is 75% of the reference length Lyc and an opening area that is 75% of the reference area Sc. The decreasing change in the opening area of ​​the first slits 63 in the first section F1 may be linear or trigonometric.

[0087] A plurality of second slits 64 are arranged in the second section F2. It is preferable that the opening area of ​​each of the plurality of second slits 64 arranged in the second section F2 is smaller in the direction toward the mask end 44. This allows the opening area of ​​the two slits 61 arranged on the straight line Ey in the joint portion 43 to be adjusted to a desired range while continuously changing the exposure amount in the boundary portion between the non-overlapped region 29a and the overlapped region 29b along the cross direction V. As a result, it is possible to make it difficult for a luminance change to occur over the entire joint portion 43. In the example shown in FIG. 11, the second slit 64 arranged first from the center line Ec in the second section F2 has a length Ly of 25% of the reference length Lyc and an opening area of ​​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 may be trigonometric.

[0088] The second embodiment described above has the same effect as the first embodiment. 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 of the joint portion 43, the exposure amount at the boundary between the non-overlapping region 29a and the overlapping region 29b can be changed continuously along the cross direction V. This makes it possible to effectively prevent a sudden change in luminance from occurring in the overlapping region 29b.

[0089] In particular, in the first section F1, the opening area of ​​the first slit 63 is reduced in the direction away from the non-overlap region 45, thereby making it possible to continuously and smoothly change the exposure amount at the boundary between the non-overlap region 29a and the overlap region 29b. This makes it possible to more effectively prevent abrupt changes in luminance in the overlap region 29b.

[0090] 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. However, 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, as shown in Fig. 12, the opening area of ​​the first slit 63 may be gradually reduced toward 90% of the reference area Sc by gradually shortening the length Ly of the first slit 63 toward 90% of the reference length Lyc. At this time, the opening area of ​​the second slit 64 may be gradually reduced from 10% of the reference area Sc by gradually shortening the length Ly of the second slit 64 from 10% of the reference area Lyc.

[0091] In the second embodiment described above, the first section F1 may be provided with a decreasing section in which the opening area of ​​the first slit 63 gradually decreases in a direction away from the non-overlapping region 45, and a constant section in which the opening area of ​​the first slit 63 is constant. The number and combination of the decreasing section and the constant section in the first section F1 are not particularly limited. For example, in the first section F1, a decreasing section may be arranged adjacent to the non-overlapping region 45, and a constant section may be arranged adjacent to the decreasing section. Also, a decreasing section, a constant section, and a decreasing section may be arranged in this order in the direction from the non-overlapping region toward the center line Ec.

[0092] Third Embodiment Next, a third embodiment of the manufacturing method of the present disclosure will be described. In the third embodiment, the arrangement of the slits 61 (photomask pattern) in the joint portion 43 of the photomask 40 is different from that of the first and second embodiments. Specifically, the photomask 40 of the third embodiment has a third section F3 provided between the first section F1 and the second section F2 in addition to the first section F1 and the second section F2 in the second embodiment. In the following description, the description of the same configuration as the first and second embodiments will be omitted, and the differences from the first and second embodiments will be mainly described.

[0093] Fig. 13 shows the configuration of the photomask 40 in the third embodiment. 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. In the example shown in Fig. 13, of the two sections divided by the center line Ec, a part of the region including the boundary portion 47 with the non-overlapping region 45 is the first section F1, and a part of the region including the mask end 44 is the second section F2. The length Ly and arrangement of the slits 61 in the first section F1 and the second section F2 are the same as those in the second embodiment.

[0094] The third section F3 is provided between the first section F1 and the second section F2 at the joint 43. A plurality of first slits 63 are arranged in the third section F3. In the example shown in Fig. 13, the third section F3 has a photomask pattern similar to that of the overlap region 46 in the first embodiment.

[0095] Specifically, in the third section F3, the slits 61b are arranged at intervals equal to the pixel pitch Px in the direction along the intersecting direction V (i.e., at equal intervals). In addition, in the third section F3, a first slit 63 and a second slit 64 are arranged as the slits 61b. The first slit 63 has a length Ly that is 75% of the reference length Lyc, and has an opening area that is 75% of the reference area Sc. In addition, the second slit 64 has a length Ly that is 25% of the reference length Lyc, and has an opening area that is 25% of 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. In addition, in the third section F3 of each 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 respect to the center line Ec of the overlapping region 46 as an axis, and the first slit 63 is arranged at a position symmetrical to the second slit 64.

[0096] In the third section F3, the sum ΣS 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 to the first section F1 due to the discrete density 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 to the first section F1. The increasing change in the opening area of ​​the slits 61b in the third section F3 may be linear or trigonometric. In the example shown in FIG. 13, in the third section F3, the slits 61b composed of the first slits 63 and the second slits 64 are arranged at equal intervals and so that the number of the first slits 63 included per unit area (i.e., the frequency of the first slits 63) is increased.

[0097] The third embodiment described above has an effect corresponding to the same configuration as the first embodiment. In the third embodiment, in addition to the first section F1 and the second section F2, the photomask 40 further includes a third section F3 between the first section F1 and the second section F2. In the third section F3, the first slits 63 are densely arranged in the direction from the second section F2 to the first section F1, so that the opening area of ​​the slits 61b in the joint portion 43 can be smoothly changed while obtaining the effect of suppressing the increase in brightness due to the arrangement of the first slits 63. In addition, since the first section F1 is provided at a position adjacent to the non-overlapping region 45 of the joint portion 43, the change in the amount of exposure at the boundary portion between the non-overlapping region 29a and the overlapping region 29b can be made to be a continuous change, and the occurrence of a sudden change in brightness in the overlapping region 29b can be effectively suppressed.

[0098] In the above embodiment, the opening area of ​​the first slit 63 is gradually decreased toward 75% of the reference area Sc in the first section F1, and the opening area of ​​the second slit 64 is gradually decreased from 25% of the reference area Sc, and the opening area of ​​the first slit 63 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 in the third section F3, but the opening areas of the first slit 63 and the second slit 64 are not limited to the above. For example, as shown in Fig. 14, the opening area of ​​the first slit 63 may be set to 90% or more of the reference area Sc by making the length Ly of the first slit 63 not less than 90% of the reference length Lyc, and the opening area of ​​the second slit 64 may be set to 10% or less of the reference area Sc by making the length Ly of the second slit 64 not exceed 10% of the reference length Lyc.

[0099] In the third embodiment described above, the first section F1 may also be provided with 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. The second section F2 may also be provided with 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.

[0100] Fourth Embodiment Next, a fourth embodiment of the manufacturing method of the present disclosure will be described. In the fourth embodiment, the arrangement of the slits 61 (photomask pattern) in the joint portion 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 overlapping region 46 of each of the first photomask 41 and the second photomask 42, as in the third embodiment. However, the photomask 40 of the fourth embodiment is different from the third embodiment in that the third section F3 has the first slits 63 but does not have the second slits 64, and the slits 61b are not arranged at equal intervals. In the following description, the description of the same configurations as the first to third embodiments will be omitted, and the differences from the first to third embodiments will be mainly described.

[0101] FIG. 15 shows the configuration of the photomask 40 in the fourth embodiment. The first slits 63 arranged in the third section F3 are the same as the slits 61a arranged in the non-overlapping region 45, and have a length Ly that is a reference length Lyc and an opening area that is a reference area Sc. In the third section F3, the first slits 63 are densely arranged in the direction from the second section F2 to the first section F1 by changing the distribution density of the first slits 63 in the cross direction V. As a result, the sum ΣS 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 to the first section F1. When viewed in the scanning direction W, the first slits 63 are arranged on the straight line Ey in one of the first photomask 41 and the second photomask 42, and the light-shielding portion 62b is arranged in the other photomask.

[0102] Even with the mask pattern of the photomask 40 of the fourth embodiment, the first slits 63 are densely arranged in the third section F3 in the direction from the second section F2 to the first section F1, so that it is possible to obtain the effect of suppressing an increase in luminance by the arrangement of the first slits 63 and to smooth the change in the opening area of ​​the slits 61b in the seam 43. In addition, since the first section F1 is provided at a position of the seam 43 adjacent to the non-overlapping region 45, it is possible to make the change in the exposure amount at the boundary between the non-overlapping region 29a and the overlapping region 29b a continuous change, and as a result, it is possible to effectively suppress display unevenness due to a sudden change in luminance in the overlapping region 29b.

[0103] The liquid crystal display device 10 of the present disclosure described above can be effectively applied to various uses. The liquid crystal display device 10 can be used as various display devices such as watches, portable game machines, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors, liquid crystal televisions, and information displays.

[0104] In addition, if two photomasks are simply joined together to form seam 43 without changing the opening area of ​​slit 61, as in photomask 100 shown in Figure 16, the difference in brightness between two adjacent light sources will appear on the display screen as a difference in brightness at the seam between the exposed area through one photomask and the exposed area through the other photomask, and the seam will be easily visible to the observer.

[0105] 17 has a halftone portion in the seam 43 where the opening area of ​​the slit 61 continuously decreases in the direction from the non-overlapping region 45 toward the mask end 44. In exposure through the photomask 200, the slits 61 with opening areas where the exposure amounts of each overlapping exposure are similar are arranged in the seam 43 (parts surrounded by dashed lines in FIG. 17). For this reason, the seam 43 becomes locally bright in the areas where the exposure amounts of each exposure are similar, which causes band-like unevenness on the display screen and is likely to lead to a decrease in display quality. [Explanation of symbols]

[0106] 10...liquid crystal display device, 29...organic film, 29a...non-overlapping region, 29b...overlapping region, 30...pixel, 36...light source, 38...substrate, 40...photomask, 41...first photomask, 42...second photomask, 43...joint, 44...mask end, 45...overlapping region, 46...non-overlapping region, 50...exposure device, 61, 61a, 61b...slit (light-transmitting portion), 62, 62a, 62b...light-shielding portion, 63...first slit (first light-transmitting portion), 64...second slit (second light-transmitting portion), F1...first section, F2...second section, F3...third section, V...crossing direction, W...scanning direction

Claims

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

2. the photomask includes a first photomask and a second photomask arranged adjacent to each other along a cross direction that crosses the moving direction and is a direction along a substrate surface, the first photomask and the second photomask are arranged such that a portion of each of them overlaps when viewed in the moving direction; the non-overlapping region is a region in which the first photomask and the second photomask do not overlap when viewed in the movement direction, The method for manufacturing a liquid crystal display device according to claim 1 , wherein the overlapping region is a region where the first photomask and the second photomask overlap when viewed in the movement direction.

3. 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 movement direction.

4. 4. The method for manufacturing a liquid crystal display device according to claim 2, wherein the light-transmitting portions are arranged in the overlapping region such that a sum of the opening areas of the light-transmitting portions included in a region of a predetermined length along the intersecting direction shows an increasing tendency from an end 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 of the photomask toward the non-overlapping region.

6. the overlap region has a first section adjacent to the non-overlapping region and a second section including an edge of a photomask; The first section includes the first light transmitting portion and the second light transmitting portion is not disposed in the first section, The method for manufacturing a liquid crystal display device according to claim 2 , wherein the second light transmitting portion is arranged in the second section, and the first light transmitting portion is not arranged in the second section.

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

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

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

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

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

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

13. 3. The method for manufacturing a liquid crystal display device according to claim 1, wherein in the exposure step, polarized ultraviolet light is irradiated obliquely onto the substrate surface.

14. 3. The method for producing a liquid crystal display device according to claim 1, wherein the liquid crystal layer contains liquid crystal molecules having negative dielectric anisotropy.

15. A liquid crystal display device manufactured by the manufacturing method according to claim 1 or 2.

16. An exposure apparatus for manufacturing a photo-alignment film, A light source; A plurality of photomasks; a scanning unit that exposes a substrate having a photosensitive organic film through the plurality of photomasks while moving the substrate in a predetermined moving direction relative to the light source; Equipped with the plurality of photomasks are arranged side by side in an intersecting direction that intersects the moving direction and is a direction along a substrate surface, 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 a portion of each of them overlaps with each other when viewed in the movement direction; each of the first photomask and the second photomask has, in a non-overlapping region where the first photomask and the second photomask do not overlap as viewed in the movement direction, a plurality of light-transmitting portions having the same opening area and a light-shielding portion provided between each of the light-transmitting portions, and, in an overlapping region where the first photomask and the second photomask overlap as viewed in the movement direction, a plurality of light-transmitting portions having different opening areas and a light-shielding portion provided between each of the light-transmitting portions; At least a portion of the plurality of light-transmitting portions arranged in the overlapping region has an opening area smaller than that of the light-transmitting portions arranged in the non-overlapping region, an exposure apparatus, wherein each light-transmitting portion disposed in the overlapping region is a first light-transmitting portion having an opening area that is 75% or more and 100% or less of an opening area of ​​each light-transmitting portion disposed in the non-overlapping region, or is a second light-transmitting portion having an opening area that is more than 0% and 25% or less.

Images