Liquid crystal display device

Abstract

To provide a liquid crystal display device that can suppress the decrease in contrast. [Solution] A liquid crystal display device comprising, in order, a first substrate having a plurality of gate lines extending in a first direction, a plurality of source lines extending in a second direction, a first electrode and a second electrode, a first alignment film, a liquid crystal layer containing liquid crystal molecules, and a second substrate, wherein the second electrode is provided with a longitudinally shaped opening, the first substrate has a stepped portion extending in a third direction on the surface facing the first alignment film, and in a plan view, the angle α between the alignment direction of liquid crystal molecules located near the first alignment film and in the center of the opening in a voltage-free state and the third direction is greater than 0° and less than 90°, and the parameter P, expressed by the following formula (1) using the angle α, the taper angle β of the stepped portion and the contact angle θa of the first alignment film with pure water, is 0.77 or less. TIFF2026052957000008.tif9156 (However, if the taper angle β exceeds 90°, β = 90° in equation (1).)

Description

Technical Field

[0001] The following disclosure relates to a liquid crystal display device.

Background Art

[0002] As a technology related to liquid crystal display devices, Patent Document 1 discloses a horizontal electric field type liquid crystal display device having a first substrate, a second substrate facing the first substrate, a liquid crystal layer provided between the first and second substrates, pixel electrodes and a common electrode formed on a surface of the first substrate facing the second substrate and generating an electric field parallel to the first substrate between them. As a pixel region between the pixel electrode and the common electrode, the shapes of the pixel electrode and the common electrode are set such that a main portion where the electric field direction is orthogonal to the initial alignment direction of liquid crystal molecules and a specific portion smaller than the main portion where the electric field direction is not orthogonal are formed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a liquid crystal display device capable of suppressing a decrease in contrast.

Means for Solving the Problems

[0005] (1) One embodiment of the present invention comprises, in order, a first substrate having a plurality of gate lines, a plurality of source lines, a plurality of nonlinear elements arranged corresponding to the intersection of each gate line and each source line, a first electrode, and a second electrode; a first alignment film; a liquid crystal layer containing liquid crystal molecules; and a second substrate, wherein the plurality of gate lines extend in a first direction, the plurality of source lines extend in a second direction intersecting the first direction, the first electrode and the second electrode face each other at least partially via an insulating layer, and one of the first electrode and the second electrode is connected via a nonlinear element corresponding to that electrode. A liquid crystal display device, connected to a source line corresponding to the electrode, the second electrode having a longitudinally shaped opening, the first substrate having a stepped portion extending in a third direction on the surface facing the first alignment film, the angle α between the orientation direction of liquid crystal molecules located near the first alignment film and in the center of the opening in a voltage-free state and the third direction in a plan view is greater than 0° and less than 90°, and the parameter P, expressed by the following formula (1) using the angle α, the taper angle β of the stepped portion, and the contact angle θa of the first alignment film with pure water, is 0.77 or less.

number

[0006] (2) In addition, one embodiment of the present invention is a liquid crystal display device in which, in addition to the configuration of (1) above, the parameter P represented by formula (1) above is 0.074 or more.

[0007] (3) In addition, one embodiment of the present invention is a liquid crystal display device in which, in addition to the configuration of (1) or (2) above, the pre-tilt angle of the liquid crystal molecules located near the first alignment film is 0° or more and 3° or less.

[0008] (4) In addition, one embodiment of the present invention is a liquid crystal display device in which, in addition to the configuration of (1), (2) or (3) above, the taper angle β of the stepped portion is 60° or more and 90° or less.

[0009] (5) In addition, one embodiment of the present invention is a liquid crystal display device in which, in addition to the configuration of (1), (2), (3) or (4) above, the orientation direction of the liquid crystal molecules located in the vicinity of the first orientation film and in the central part of the opening in a plan view, when no voltage is applied, is parallel to or perpendicular to the first direction.

[0010] (6) In addition, one embodiment of the present invention is a liquid crystal display device in which, in addition to the configuration of (1), (2), (3), (4) or (5) above, the liquid crystal molecules have positive dielectric anisotropy, and in a plan view, the orientation direction of the liquid crystal molecules located near the first alignment film and in the center of the opening in a voltage-free state is perpendicular to the first direction, and the angle α is 3° or more and 45° or less.

[0011] (7) In addition, one embodiment of the present invention is a liquid crystal display device in which, in addition to the configuration of (1), (2), (3), (4) or (5) above, the liquid crystal molecules have negative dielectric anisotropy, and in a plan view, the orientation direction of the liquid crystal molecules located near the first alignment film and in the center of the opening in a voltage-free state is parallel to the first direction, and the angle α is 45° or more and 87° or less.

[0012] (8) In addition, one embodiment of the present invention is a liquid crystal display device in which, in addition to the configuration of (1), (2), (3), (4), (5), (6) or (7) above, the stepped portion includes the end of the opening of the second electrode.

[0013] (9) In addition, one embodiment of the present invention is a liquid crystal display device in which, in addition to the configuration of (1), (2), (3), (4), (5), (6) or (7) above, the first substrate is further provided with a light-shielding film on the liquid crystal layer side of the second electrode, and the stepped portion includes the end of the light-shielding film.

[0014] (10) In addition, one embodiment of the present invention is a liquid crystal display device in which, in addition to the configuration of (9) above, the stepped portion further includes the end of the opening of the second electrode.

[0015] (11) In addition, one embodiment of the present invention is a liquid crystal display device in which, in addition to the configuration of (9) or (10) above, the light-shielding film is a metal film, or a laminate comprising a metal film and an inorganic insulating film.

[0016] (12) In addition, one embodiment of the present invention is a liquid crystal display device in which, in addition to the configuration of (1), (2), (3), (4), (5), (6), (7), (8), (9), (10), or (11) above, the alignment film is a photoalignment film that has been subjected to an alignment treatment by polarized ultraviolet irradiation.

[0017] (13) In addition, one embodiment of the present invention is a liquid crystal display device wherein, in addition to the configuration of (1), (2), (3), (4), (5), (6), (7), (8), (9), (10), (11), or (12) above, the height of the stepped portion is greater than the average thickness of the first orientation film.

[0018] (14) In addition, one embodiment of the present invention is a liquid crystal display device in which, in addition to the configuration of (1), (2), (3), (4), (5), (6), (7), (8), (9), (10), (11), (12), or (13) above, the first substrate further comprises a color filter layer.

[0019] (15) In addition, one embodiment of the present invention is a liquid crystal display device comprising, in addition to the configurations of (1), (2), (3), (4), (5), (6), (7), (8), (9), (10), (11), (12), (13), or (14) above, a first polarizing plate disposed on the opposite side of the first substrate from the liquid crystal layer and having a first polarizing axis parallel to or perpendicular to the first direction, and a second polarizing plate disposed on the opposite side of the second substrate from the liquid crystal layer and having a second polarizing axis perpendicular to the first polarizing axis. [Effects of the Invention]

[0020] According to the present invention, a liquid crystal display device capable of suppressing a decrease in contrast can be provided.

Brief Description of the Drawings

[0021] [Figure 1] It is a plan schematic view of a liquid crystal display device according to Embodiment 1. [Figure 2] It is a cross-sectional schematic view of a liquid crystal display device according to Embodiment 1 along the line A1 - A2 in FIG. 1. [Figure 3] It is a cross-sectional schematic view of a liquid crystal display device according to Embodiment 1 along the line B1 - B2 in FIG. 1. [Figure 4] It is a plan schematic view of a liquid crystal display device of the FFS mode of a comparative example containing liquid crystal molecules having a positive dielectric anisotropy. [Figure 5] It is a plan schematic view of a liquid crystal display device of the FFS mode of a comparative example containing liquid crystal molecules having a negative dielectric anisotropy. [Figure 6] It is a plan view for explaining the angle α. [Figure 7] It is a cross-sectional view for explaining the taper angle β. [Figure 8] It is a diagram for explaining the relationship between the reciprocal of the contact angle and the pretilt angle. [Figure 9] It is a schematic view showing a method for determining the taper angle β when the components of the step portion are one layer. [Figure 10] It is a schematic view showing a method for determining the taper angle β when the components of the step portion are two layers. [Figure 11] It is a plan schematic view of a liquid crystal display device according to Embodiment 2. [Figure 12] It is a plan schematic view of a liquid crystal display device according to Modification 1 of Embodiments 1 and 2. [Figure 13] It is a plan schematic view of a liquid crystal display device according to Modification 2 of Embodiments 1 and 2. [Figure 14] It is an example of a scanning electron micrograph of the liquid crystal display devices of Examples 1 to 4.

Modes for Carrying Out the Invention

[0022] Embodiments of the present invention will be described below. The present invention is not limited to the embodiments described below, and design modifications can be made as appropriate within the scope of satisfying the configuration of the present invention. In the following description, the same reference numerals will be used in common across different drawings for the same parts or parts having similar functions, and repeated descriptions will be omitted as appropriate. Each aspect of the present invention may be combined as appropriate without departing from the spirit of the present invention.

[0023] Embodiments of the present invention will be described below. The present invention is not limited to the embodiments described below, and design modifications can be made as appropriate within the scope of satisfying the configuration of the present invention.

[0024] (Embodiment 1) Figure 1 is a schematic plan view of a liquid crystal display device according to Embodiment 1. Figure 2 is a schematic cross-sectional view of the liquid crystal display device according to Embodiment 1 along the line A1-A2 in Figure 1. Figure 3 is a schematic cross-sectional view of the liquid crystal display device according to Embodiment 1 along the line B1-B2 in Figure 1.

[0025] As shown in Figures 1 to 3, the liquid crystal display device 1 of this embodiment comprises, in order, a first substrate 100 having a plurality of gate lines 120L, a plurality of source lines 150L, ​​a plurality of nonlinear elements 100T arranged corresponding to the intersections of each gate line 120L and each source line 150L, ​​a first electrode 100E1, and a second electrode 100E2; a first alignment film 410; a liquid crystal layer 300 containing liquid crystal molecules 300L; and a second substrate 200. The plurality of gate lines 120L extend in a first direction 11D, and the plurality of source lines 150L extend in a second direction 12D that intersects the first direction 11D. The first electrode 100E1 and the second electrode 100E2 face each other at least partially via an insulating layer 100F. One of the first electrode 100E1 and the second electrode 100E2 is connected to the source line 150L corresponding to that electrode via a nonlinear element 100T corresponding to that electrode. The second electrode 100E2 is provided with a longitudinally shaped opening 100E2X. The first substrate 100 has a stepped portion 10S extending in a third direction 13D on the surface facing the first alignment film 410. In a plan view, the angle α between the orientation direction (also called the reference orientation direction) 301A and the third direction 13D of the liquid crystal molecule 300L located near the first alignment film 410 and in the center of the opening 100E2X, when no voltage is applied, is greater than 0° and less than 90°. The parameter P, expressed by the following formula (1) using the angle α, the taper angle β of the stepped portion 10S, and the contact angle θa of the first alignment film 410, is 0.77 or less. By adopting this configuration, a decrease in the contrast of the liquid crystal display device 1 can be suppressed. Here, the reference orientation direction 301A is the original orientation direction of the liquid crystal molecule, and is the orientation direction of the liquid crystal molecule in a region unaffected by the stepped portion 10S when no voltage is applied. The orientation direction of liquid crystal molecules located near the alignment film and in the center of the opening, under no applied voltage, corresponds to the original orientation direction unaffected by the step.

[0026]

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[0027] Figure 4 is a schematic plan view of a comparative example FFS mode liquid crystal display device containing liquid crystal molecules with positive dielectric anisotropy. Figure 5 is a schematic plan view of a comparative example FFS mode liquid crystal display device containing liquid crystal molecules with negative dielectric anisotropy. For liquid crystal displays for head-mounted displays, the FFS (Fringe Field Switching) mode liquid crystal display device 1R shown in Figures 4 and 5 may be used to suppress color shift within the viewing angle.

[0028] Furthermore, from the viewpoint of securing aperture area through high resolution, it is advantageous to form the color filter layer 170CFR on the array substrate 100R. However, forming the color filter layer 170CFR on the array substrate 100R makes oblique color mixing more likely. This oblique color mixing can be suppressed by covering a part of the display area with a light-shielding film 100MR.

[0029] As shown in Figures 4 and 5, the slits (openings 100EXR) of the light-shielding film 100MR and the electrodes 100ER provided on the array substrate 100R create irregularities (stepped portions 10S) on the array substrate 100R. Furthermore, when the edge of the light-shielding film 100MR and the boundary of the slits (openings 100EXR) of the electrodes 100ER overlap, a stepped portion 10S2 is formed that is larger than the stepped portion 10S1 formed solely by the slits (openings 100EXR) of the electrodes 100ER.

[0030] In the region where the stepped portion 10S is located, a deviation in the orientation direction of the liquid crystal molecules (liquid crystal director) from the original orientation direction (reference orientation direction 301A) may occur. In region R2 where a larger stepped portion 10S2 is located, the amount of deviation in the orientation direction of the liquid crystal molecules tends to be greater than in region R1 where a smaller stepped portion 10S1 is located. Furthermore, in the region where the stepped portion 10S is located, the orientation direction of the liquid crystal molecules may not deviate from the original orientation direction toward the extension direction 10SD of the stepped portion 10S, but rather deviate in the opposite direction. In the liquid crystal display device 1R shown in Figures 4 and 5, a deviation in the orientation direction of the liquid crystal molecules from the original orientation direction occurs in the region where the stepped portion 10S is located, which may result in a decrease in contrast when displaying black.

[0031] As a result of our investigation, we have found that the decrease in contrast is influenced by stepped portions extending in a direction different from the original orientation direction of the liquid crystal molecules (reference orientation direction), and by the alignment film material (especially the polarity of the surface).

[0032] Figure 6 is a plan view illustrating angle α. Figure 7 is a cross-sectional view illustrating taper angle β. Figures 6 and 7 are diagrams illustrating angle α and taper angle β in equation (1). It was found that the occurrence of light leakage is determined by (A) to (C) below. Details of angle α and taper angle β are shown in Figures 6 and 7, respectively. In addition, the contact angle (surface contact angle) θa of the alignment film can be measured using a contact angle meter with pure water as the medium.

[0033] (A) Surface properties of the oriented film (contact angle θa) (B) Angle α between the extension direction of the stepped portion 10S in a plan view (third direction 13D) and the original orientation direction of the liquid crystal molecules (reference orientation direction 301A) (C) Taper angle β of the stepped section 10S (however, if it is a reverse taper, β = 90°)

[0034] The weaker the adsorption force of liquid crystal molecules to the alignment film surface, the lower the thermal stability of the alignment film. As a result, the liquid crystal molecules become more prone to rotation, and the orientation direction of the liquid crystal molecules deviates more from the original orientation direction (reference orientation direction 301A). In a plan view, this deviation is thought to be maximum when the angle between the extension direction of the stepped portion 10S (third direction 13D) and the original orientation direction of the liquid crystal molecules (reference orientation direction 301A) is 45°. Similarly, the larger the taper angle β of the stepped portion 10S and the steeper the stepped portion 10S, the more the orientation direction of the liquid crystal molecules deviates more from the original orientation direction (reference orientation direction 301A).

[0035] As a result of our investigation, we found that the surface adsorption force of the alignment film and the characteristics of the stepped portion can be represented by the parameter P in the above formula (1), and that when the parameter P represented by the following formula (1) is 0.77 or less, the decrease in contrast of the liquid crystal display device can be suppressed.

[0036] In equation (1) above, (θa / 90°) is a parameter that depends on the surface tension of the alignment film surface. In equation (1), {1+2sin(α)×cos(α)} indicates that the difference (also called phase shift) between the alignment direction of liquid crystal molecules near the step portion 10S and the reference alignment direction 301A is maximum when the angle between the extension direction of the step portion 10S (third direction 13D) and the reference alignment direction 301A of the liquid crystal molecules is 45°. In equation (1), sin(β) indicates that the steeper the step portion 10S (larger taper angle), the larger the phase shift.

[0037] Here, we will explain the relationship between the contact angle (or its reciprocal) and the pretilt angle. Figure 8 illustrates the relationship between the reciprocal of the contact angle and the pretilt angle. As shown in Figure 8, as the contact angle of the alignment film increases, the pretilt angle increases, and the dependence on the alignment film material (material system A1, material system A2, and material system A3) decreases. Typically, the pretilt angle can be increased by introducing side chains into the material system (polymer material).

[0038] As the contact angle of the orientation film decreases, the pre-tilt angle decreases, and the dependence of the pre-tilt angle on the orientation film material increases. The smaller the contact angle, the higher the surface tension. Material systems with higher surface tension have higher thermal stability.

[0039] Equation (1) above represents parameters related to surface tension; a smaller value indicates higher surface tension. Furthermore, the presence and shape (angle α, taper angle β) of stepped sections affect surface tension. As a result, light leakage and other issues may occur under certain conditions.

[0040] In this specification, the pre-tilt angle refers to the angle that the long axis of a liquid crystal molecule makes with respect to the surface of the substrate when no voltage is applied, with the substrate surface being 0° and the substrate normal being 90°. In this specification, the voltage-applied state, in which a voltage above a threshold is applied between the first electrode and the second electrode (pixel electrode and common electrode), is also simply referred to as the "voltage-applied state," and the voltage-free state, in which a voltage below a threshold is applied between the first electrode and the second electrode (including no voltage applied), is also simply referred to as the "voltage-free state."

[0041] In the above-mentioned Patent Document 1, in an IPS (In-Plane Switching) mode liquid crystal display device, diagonal wiring is eliminated in many areas of the pixels to improve transmittance. However, it is extremely difficult to realize the electrode structure disclosed in Patent Document 1 in a high-definition liquid crystal display device such as those used in head-mounted displays. Furthermore, even if it could be realized, the orientation of liquid crystal molecules becomes unstable in areas where the pixel electrodes are not angled (i.e., areas where the outer edge of the pixel electrode is parallel to the vertical or horizontal direction of the panel outline), which may reduce the operating speed. Therefore, it is difficult to suppress the decrease in display contrast with the above-mentioned Patent Document 1. The liquid crystal display device 1 of this embodiment will be described in detail below.

[0042] As shown in Figures 2 and 3, the liquid crystal display device 1 of this embodiment comprises, in order, a first substrate 100, a liquid crystal layer 300, and a second substrate 200. In this embodiment, the first substrate 100 is arranged on the back side and the second substrate 200 is arranged on the observation side, but the first substrate 100 may be arranged on the observation side and the second substrate 200 may be arranged on the back side.

[0043] The liquid crystal display device 1 includes a first alignment film 410 between the first substrate 100 and the liquid crystal layer 300. The liquid crystal display device 1 may also include a second alignment film 420 between the second substrate 200 and the liquid crystal layer 300.

[0044] Preferably, the liquid crystal display device 1 comprises a first polarizing plate 510 positioned on the opposite side of the liquid crystal layer 300 of the first substrate 100 and having a first polarizing axis parallel to or perpendicular to the first direction 11D, and a second polarizing plate 520 positioned on the opposite side of the liquid crystal layer 300 of the second substrate 200 and having a second polarizing axis perpendicular to the first polarizing axis.

[0045] Unless otherwise specified, in this specification, two straight lines (including the polarization axes and directions) are said to be orthogonal if the angle between them is 87° or more and 90° or less, preferably 89° or more and 90° or less, more preferably 89.5° or more and 90° or less, and particularly preferably 90° (perfectly orthogonal). Also in this specification, two straight lines (including the polarization axes and directions) are said to be parallel if the angle between them (absolute value) is 0° or more and 3° or less, preferably 0° or more and 1° or less, more preferably 0° or more and 0.5° or less, and particularly preferably 0° (perfectly parallel).

[0046] The liquid crystal display device 1 may also be equipped with a backlight on the side of the first polarizing plate 510 opposite to the liquid crystal layer 300.

[0047] The liquid crystal display device 1 includes an active area (image display area) on which an image is displayed. The active area is composed of a plurality of pixels 10P arranged in a matrix in the horizontal direction of the screen (first direction 11D in this embodiment) and the vertical direction of the screen (second direction 12D in this embodiment).

[0048] The first substrate 100 comprises a first support substrate 110, a plurality of gate lines 120L extending parallel to each other in a first direction 11D on the liquid crystal layer 300 side of the first support substrate 110, a first insulating layer 130 disposed on the liquid crystal layer 300 side of the plurality of gate lines 120L, and a plurality of source lines 150L extending parallel to each other in a second direction 12D on the liquid crystal layer 300 side of the first insulating layer 130. The plurality of gate lines 120L and the plurality of source lines 150L are formed in a grid pattern as a whole to demarcate each pixel 10P. Nonlinear elements 100T are arranged at the intersections of each gate line 120L and each source line 150L. In this embodiment, the first direction 11D is perpendicular to the second direction 12D. In this embodiment, the first direction 11D corresponds to the row direction of the matrix-arranged pixels 10P (hereinafter sometimes simply referred to as the "row direction"), and the second direction 12D corresponds to the column direction of the matrix-arranged pixels 10P (hereinafter sometimes simply referred to as the "column direction"). However, the first direction 11D may correspond to the column direction of the pixels 10P, and the second direction 12D may correspond to the row direction.

[0049] Each nonlinear element 100T is connected to the corresponding gate line 120L and source line 150L from among a plurality of gate lines 120L and a plurality of source lines 150L, ​​and comprises a gate electrode protruding from the corresponding gate line 120L (which is part of the gate line 120L), a source electrode protruding from the corresponding source line 150L (which is part of the source line 150L), a drain electrode 150D connected to the corresponding pixel electrode from among a plurality of pixel electrodes (first electrode 100E1 in this embodiment), and a three-terminal switch having a semiconductor layer (for example, a thin film transistor (TFT)). The source electrode and drain electrode 150D are electrodes provided in the same source wiring layer 150 as the source line 150L, ​​and the gate electrode is an electrode provided in the same gate wiring layer 120 as the gate line 120L. The first electrode 100E1 is connected to the drain electrode 150D via a through-hole 10CH1.

[0050] The various wirings and electrodes constituting the gate wire 120L, source wire 150L, ​​and nonlinear element 100T can be formed by depositing metals such as copper, titanium, aluminum, molybdenum, and tungsten, or their alloys, in single or multiple layers using sputtering or the like, followed by patterning using photolithography or the like. For these various wirings and electrodes formed in the same layer, the manufacturing process can be made more efficient by using the same material for each component.

[0051] The first substrate 100 comprises, in order toward the liquid crystal layer 300 side, a first support substrate 110, a gate wiring layer 120 on which gate lines 120L are provided, a first insulating layer 130, a semiconductor layer, a source wiring layer 150 on which source lines 150L are provided, a second insulating layer 160, a color filter layer 170, a planarization film 180, a first electrode 100E1, an insulating layer 100F, a second electrode 100E2 on which an opening 100E2X is provided, and a light-shielding film 100M.

[0052] The first insulating layer 130 is a gate insulating layer. The first insulating layer 130 is, for example, an inorganic insulating film. As an inorganic insulating film, for example, silicon nitride (SiN x ), inorganic films such as silicon dioxide (SiO2) (with relative permittivity ε=5~7), or laminated films thereof can be used.

[0053] The semiconductor layer is composed of, for example, a high-resistance semiconductor layer made of amorphous silicon, polysilicon, etc., and a low-resistance semiconductor layer made of n+ amorphous silicon, which is amorphous silicon doped with impurities such as phosphorus. Alternatively, the semiconductor layer may be an oxide semiconductor layer such as indium gallium zinc oxide (IGZO).

[0054] The second insulating layer 160 is, for example, an inorganic insulating film. Examples of inorganic insulating films include silicon nitride (SiN). x ), inorganic films such as silicon dioxide (SiO2) (with relative permittivity ε=5~7), or laminated films thereof can be used.

[0055] The first substrate 100 includes a color filter layer 170. The color filter layer 170 is located on the liquid crystal layer 300 side of the second insulating layer 160. The color filter layer 170 consists of a red color filter 170R, a blue color filter 170B, and a green color filter 170G.

[0056] Multiple pixels 10P include a red pixel 10PR equipped with a red color filter 170R, a blue pixel 10PB equipped with a blue color filter 170B, and a green pixel 10PG equipped with a green color filter 170G. Three pixels 10P—red pixel 10PR, blue pixel 10PB, and green pixel 10PG—constitute a single pixel 1P. Within a single pixel 1P, these three pixels 10P are arranged in a striped pattern.

[0057] In this embodiment, the first substrate 100 has a color filter layer 170, but the second substrate 200 may have the color filter layer 170 instead of the first substrate 100.

[0058] The planarization film 180 is an insulating film that absorbs irregularities on the surface (substrate) on which the film is formed, and flattens the substrate surface on which the film is formed. The planarization film 180 makes it possible to maintain a constant cell thickness in the liquid crystal display device 1. An organic insulating film is preferred as the planarization film 180. As the organic insulating film, for example, an organic film such as acrylic resin, polyimide resin, or novolac resin can be used. As the organic insulating film, for example, an organic film with a low relative permittivity (relative permittivity ε = 2 to 5), such as a photosensitive acrylic resin, can be preferably used.

[0059] The first substrate 100 comprises a first electrode 100E1 and a second electrode 100E2 having an opening 100E2X, which are at least partially opposite each other via an insulating layer 100F. That is, the first substrate 100 comprises, in order, the first electrode 100E1, the insulating layer 100F, and the second electrode 100E2 having a longitudinally shaped opening 100E2X. By adopting this configuration, a display mode for FFS mode can be realized. One of the first electrode 100E1 and the second electrode 100E2 is connected to the source line 150L corresponding to that electrode via a nonlinear element 100T corresponding to that electrode. Here, "partially opposite each other" means that at least a part of the first electrode 100E1 faces at least a part of the second electrode 100E2.

[0060] One of the first electrode 100E1 and the second electrode 100E2 is a pixel electrode, and the other electrode is a common electrode. In this embodiment, the first electrode 100E1 is a pixel electrode, and the second electrode 100E2 is a common electrode.

[0061] Pixel electrodes are electrodes positioned in each region enclosed by two adjacent gate lines 120L and two adjacent source lines 150L. Pixel electrodes are positioned at each pixel 10P. Each pixel electrode is connected to a corresponding nonlinear element 100T, and is connected to the corresponding source line 150L via a semiconductor layer provided by the nonlinear element 100T. The pixel electrodes are set to a potential corresponding to the data signal supplied via the corresponding nonlinear element 100T.

[0062] A common electrode is, for example, an electrode formed on almost the entire surface, regardless of the boundary of pixel 10P. A common signal, maintained at a constant value, is supplied to the common electrode, and the common electrode is maintained at a constant potential.

[0063] The second electrode 100E2 is provided with a longitudinally shaped opening 100E2X. Multiple openings 100E2X are provided in the second electrode 100E2. One of the multiple openings 100E2X is provided for each pixel 10P.

[0064] It is preferable that the second electrode 100E2 is positioned closer to the liquid crystal layer 300 than the first electrode 100E1. The opening 100E2X of the (upper layer) second electrode 100E2, which is positioned closer to the liquid crystal layer 300, is positioned on the lower layer first electrode 100E1. In this embodiment, the lower layer first electrode 100E1 is positioned in at least the region corresponding to the opening 100E2X, but there may be regions within the region corresponding to the opening 100E2X where the first electrode 100E1 is not present. For example, if the lower layer first electrode 100E1 is a common electrode, the first electrode 100E1 may be a solid electrode with an opening in the region corresponding to the through-hole connecting the upper layer second electrode 100E2, which is a pixel electrode, and the drain electrode of the nonlinear element 100T. The electric field applied to the liquid crystal molecules is determined by the potential difference between the opening 100E2X of the upper second electrode 100E2 and the lower first electrode 100E1. Therefore, in terms of the operation of the liquid crystal molecules, either the upper electrode (second electrode 100E2) or the lower electrode (first electrode 100E1) may be a pixel electrode or a common electrode. When the upper electrode is a pixel electrode, it must be electrically insulated from adjacent pixel electrodes. For example, the upper electrode has a configuration in which one opening 100E2X is provided in each square-shaped pixel electrode. On the other hand, when the upper electrode is a common electrode, the upper electrode has a configuration in which one opening is provided in the region corresponding to each pixel of a solid electrode that extends across the entire screen area (i.e., the total number of openings in the common electrode is the same as the number of pixels).

[0065] Preferably, the second electrode 100E2 is positioned closer to the liquid crystal layer 300 than the first electrode 100E1, and the first electrode 100E1 is a pixel electrode while the second electrode 100E2 is a common electrode. This configuration makes it possible to reduce the step caused by the electrodes and to easily form through holes between the pixel electrode and the drain electrode. Alternatively, the second electrode 100E2 may be positioned closer to the liquid crystal layer 300 than the first electrode 100E1, and the first electrode 100E1 may be a common electrode while the second electrode 100E2 is a pixel electrode. This configuration makes it possible to reduce the parasitic capacitance [Cgd] of the nonlinear element 100T.

[0066] The thickness of the second electrode 100E2 is preferably 30 nm or more and 150 nm or less, more preferably 30 nm or more and 100 nm or less, and even more preferably 30 nm or more and 80 nm or less. As shown in Figures 4 and 5, the step in the opening 100EXR provided in the electrode 100ER is thought to cause a shift in the orientation direction of liquid crystal molecules near the step in the voltage-free state from the originally assumed orientation direction (reference orientation direction 301A), resulting in a decrease in contrast. However, with the configuration of this embodiment, even when the thickness of the second electrode 100E2 is 30 nm or more and 150 nm or less, the decrease in contrast can be suppressed.

[0067] The first electrode 100E1 and the second electrode 100E2 can be formed by depositing a transparent conductive material such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), or tin oxide (SnO), or an alloy thereof, in a single or multiple layer by sputtering or the like, and then patterning it using photolithography.

[0068] The insulating layer 100F is an interlayer insulating film and has the function of insulating the first electrode 100E1 and the second electrode 100E2. An inorganic insulating film can be used as the insulating layer 100F. For example, silicon nitride (SiN) x ), inorganic films such as silicon dioxide (SiO2) (with relative permittivity ε=5~7), or laminated films thereof can be used.

[0069] The light-shielding film 100M is preferably longitudinal. More preferably, the light-shielding film 100M is arranged in an island-like manner between multiple pixels 10P (boundaries of pixels 10P) such that at least a portion of it overlaps the source line 150L. This configuration makes it possible to suppress color shifts during monochrome display caused by light leakage from adjacent pixels 10P, mainly at oblique viewing angles.

[0070] The light-shielding film 100M preferably contains a metal. The metal contained in the light-shielding film 100M is preferably a metal with relatively low reflectivity, such as molybdenum or titanium. The light-shielding film 100M may also contain materials other than metal. The light-shielding film 100M is, for example, a metal film, or a laminate containing a metal film and an inorganic insulating film. The laminate may be, for example, a laminate in which an insulating film such as silicon oxide or silicon nitride is sandwiched between a plurality of metal films. When the light-shielding film 100M is the above laminate, the metal film contained in the laminate is preferably a semi-transparent thin metal film layer. By adopting this configuration, the reflectivity of the light-shielding film 100M can be reduced by utilizing light interference.

[0071] The thickness of the light-shielding film 100M is preferably 40 nm or more and 250 nm or less, more preferably 100 nm or more and 250 nm or less, and even more preferably 150 nm or more and 200 nm or less. As shown in Figures 4 and 5, it is thought that the step in the light-shielding film 100MR causes the orientation direction of the liquid crystal molecules near the step to deviate from the originally assumed orientation direction (reference orientation direction 301A) when no voltage is applied, resulting in a decrease in contrast. However, with the configuration of this embodiment, even when the thickness of the light-shielding film 100M is 40 nm or more and 250 nm or less, the decrease in contrast can be suppressed.

[0072] The combined thickness of the second electrode 100E2 and the light-shielding film 100M is preferably 70 nm or more and 400 nm or less, more preferably 130 nm or more and 350 nm or less, and even more preferably 180 nm or more and 280 nm or less.

[0073] As shown in Figure 3, the first substrate 100 has a stepped portion 10S extending in a third direction 13D on the surface facing the first alignment film 410. The stepped portion 10S includes a first surface 10SX, a second surface 10SY adjacent to the first surface 10SX and located closer to the liquid crystal layer 300 than the first surface 10SX, and a third surface 10SZ (for example, an inclined surface) connecting the first surface 10SX and the second surface 10SY, and the third direction 13D is the direction in which the boundary between the first surface 10SX or the second surface 10SY and the third surface 10SZ extends.

[0074] Examples of stepped sections 10S include the following three types of stepped sections (I) to (III). (I) A step equal to the thickness of the light-shielding film 100M. That is, the stepped portion 10S includes the edge of the light-shielding film 100M. (II) A step formed by the opening 100E2X of the second electrode 100E2, the thickness of the second electrode 100E2. That is, the stepped portion 10S includes the end of the opening 100E2X of the second electrode 100E2. (III) A step formed by the light-shielding film 100M and the opening 100E2X of the second electrode 100E2, the step being equal to the thickness of the light-shielding film 100M plus the thickness of the second electrode 100E2. That is, the step portion 10S includes the edge of the light-shielding film 100M and the edge of the opening 100E2X of the second electrode 100E2. The distance between the edge of the light-shielding film 100M and the edge of the opening 100E2X included in the step portion 10S is, for example, 0 nm or more and 500 nm or less. When this distance is 0 nm or more and 500 nm or less, the step portion 10S is steep and orientation disorder of the liquid crystal molecules 300L is likely to occur, but by setting the parameter P represented by the above formula (1) to 0.77 or less, the decrease in contrast of the liquid crystal display device 1 can be suppressed.

[0075] Figure 9 is a schematic diagram showing how to determine the taper angle β when the stepped section has one layer of components. Figure 10 is a schematic diagram showing how to determine the taper angle β when the stepped section has two layers of components.

[0076] When the stepped portion 10S is composed of one layer, that is, when the stepped portion 10S is the stepped portion shown in (I) or (II) above, the taper angle β of the stepped portion 10S can be determined by drawing an approximate straight line of the slope of the stepped portion 10S, as shown in Figure 9. The approximate straight line can be determined by the least squares method.

[0077] When the stepped section 10S is composed of two layers (lower layer 10SL1 and upper layer 10SL2), that is, when the stepped section 10S is the stepped section shown in (III) above, the taper angle β can be determined by the method shown in Figure 10. Specifically, an approximate straight line of the slope of the lower layer 10SL1 at height h1 is drawn to determine the taper angle β1. Similarly, an approximate straight line of the slope of the upper layer 10SL2 at height h2 is drawn to determine the taper angle β2. The average angle β can be obtained using the following equation (2) with taper angles β1 and β2. ave. This can be defined as the taper angle β. The approximate straight line can be determined by the least squares method.

[0078]

number

[0079] As shown in Figure 3, it is preferable that the height 10SH of the stepped portion 10S is greater than the average thickness of the first alignment film 410. When the height 10SH of the stepped portion 10S is greater than the average thickness of the first alignment film 410, the orientation of the liquid crystal molecules 300L in the stepped portion 10S is disrupted and the contrast tends to decrease, but the liquid crystal display device 1 of this embodiment can effectively suppress the decrease in contrast.

[0080] The height of the stepped portion 10S is the difference in height between the first surface 10SX and the second surface 10SY of the stepped portion 10S. The height of the stepped portion can be determined by breaking the liquid crystal panel (liquid crystal display device), washing away the liquid crystal layer, and observing the cross-section of the stepped portion on the first substrate using a scanning electron microscope (SEM).

[0081] The thickness of the first alignment layer can be determined by breaking open a liquid crystal panel (liquid crystal display device), washing away the liquid crystal layer, and observing the cross-section of the alignment layer on the first substrate using a scanning electron microscope (SEM). By measuring the thickness of the first alignment layer at three locations and calculating the average value, the average thickness of the first alignment layer can be obtained.

[0082] The second substrate 200 includes a second support substrate 210.

[0083] The second substrate 200 may have a second substrate-side light-shielding film 20BM on the liquid crystal layer 300 side of the second support substrate 210. The second substrate-side light-shielding film 20BM may be provided in a grid pattern, for example, to partition each color filter.

[0084] The second substrate-side light-shielding film 20BM is, for example, a black matrix layer. The material of the black matrix layer is not particularly limited as long as it has light-shielding properties, but a resin material containing a black pigment or a metal material with light-shielding properties is preferably used. The black matrix layer is formed, for example, by a photolithography method in which a photosensitive resin containing a black pigment is applied to form a film, followed by exposure and development.

[0085] Preferably, the second substrate-side light-shielding film 20BM extends along the row direction (first direction 11D in this embodiment) between two adjacent pixels 10P in the column direction (second direction 12D in this embodiment), and is not positioned between two adjacent pixels 10P in the row direction (it is not extended along the column direction between two adjacent pixels 10P in the row direction). By adopting this configuration, peeling of the second substrate-side light-shielding film 20BM can be suppressed compared to the case where the second substrate-side light-shielding film 20BM extends both between two adjacent pixels 10P in the column direction and between two adjacent pixels 10P in the row direction. Furthermore, by adopting this configuration, the aperture ratio can be increased compared to the case where the second substrate-side light-shielding film 20BM extends in the column direction, from the viewpoint of alignment accuracy when bonding the first substrate 100 and the second substrate 200. The second substrate-side light-shielding film 20BM extends, for example, in the row direction between the outer frame of the display screen of the liquid crystal display device 1 and each pixel 10P.

[0086] A spacer may be provided between the first substrate 100 and the second substrate 200. The spacer has the function of securing a gap in the space where the liquid crystal layer 300 is formed. The spacer may have a columnar shape, for example. The spacer may be placed on at least one of the first substrate 100 and the second substrate 200, or it may be placed on both substrates. The spacer may be provided on the second substrate 200, for example, and its tip does not need to be in contact with the first substrate 100. The planar shape of the spacer may be, for example, a polygon, a circle, or an ellipse. The spacer may be, for example, a frustoconical, cylindrical, elliptical, elliptical, pyramidal, or prismatic shape. Examples of pyramidal shapes include frustoconical, square, and prismatic shapes. Examples of prismatic shapes include square and prism shapes.

[0087] The spacer 500 preferably contains, for example, a cured product of a photosensitive resin. Examples of photosensitive resins include resins having ultraviolet-reactive functional groups.

[0088] The liquid crystal layer 300 contains a liquid crystal material, and the amount of light transmitted is controlled by applying a voltage to the liquid crystal layer 300 and changing the orientation of the liquid crystal molecules 300L in the liquid crystal material according to the applied voltage. The liquid crystal material exhibits nematic liquid crystal properties within a certain temperature range.

[0089] The liquid crystal molecule 300L may have a positive or negative dielectric anisotropy (Δε) defined by the following formula (L1). In this embodiment, the liquid crystal molecule 300L has positive dielectric anisotropy. By adopting this configuration, the response speed can be improved. Δε = (dielectric constant in the long axis direction of the liquid crystal molecule) - (dielectric constant in the short axis direction of the liquid crystal molecule) Equation (L1)

[0090] Liquid crystal molecules 300L with positive dielectric anisotropy are also called positive-type liquid crystals, and liquid crystal molecules 300L with negative dielectric anisotropy are also called negative-type liquid crystals. The long axis direction of the liquid crystal molecules 300L is the orientation direction (slow axis direction). Furthermore, the liquid crystal molecules 300L are homogeneously oriented when no voltage is applied between the first electrode 100E1 and the second electrode 100E2 (no voltage applied state).

[0091] The liquid crystal molecules 300L align horizontally when no voltage is applied. Horizontal orientation of the liquid crystal molecules 300L means that when no voltage is applied to the liquid crystal layer 300 (when the applied voltage to the liquid crystal layer 300 is less than the threshold voltage), the liquid crystal molecules 300L in the liquid crystal layer 300 align substantially parallel to the main surfaces of the first substrate 100 and the second substrate 200, respectively. Here, orientation of the liquid crystal molecules substantially parallel to the main surface of the substrate means that the pre-tilt angle of the liquid crystal molecules is 0° or more and 5° or less with respect to the main surface of the substrate, preferably 0° or more and 2° or less, and more preferably 0° or more and 1° or less.

[0092] The liquid crystal display device 1 includes a first alignment film 410 disposed between a first substrate 100 and a liquid crystal layer 300. The liquid crystal display device 1 may also include a second alignment film 420 disposed between a second substrate 200 and a liquid crystal layer 300. The first alignment film 410 and the second alignment film 420 have the function of controlling the orientation of liquid crystal molecules 300L contained in the liquid crystal layer 300. The first alignment film 410 and the second alignment film 420 are horizontal alignment films.

[0093] The horizontal alignment film has the function of aligning the liquid crystal molecules in the liquid crystal layer to be substantially parallel to the main surface of the horizontal alignment film (substrate) when no voltage is applied to the liquid crystal layer. The vertical alignment film has the function of aligning the liquid crystal molecules in the liquid crystal layer to be substantially perpendicular to the main surface of the vertical alignment film (substrate) when no voltage is applied to the liquid crystal layer. Here, the orientation of the liquid crystal molecules substantially perpendicular to the main surface of the vertical alignment film (substrate) means that the pre-tilt angle of the liquid crystal molecules is 80° or more and 90° or less with respect to the main surface of the substrate, preferably 85° or more and 90° or less, and more preferably 88° or more and 90° or less.

[0094] Depending on the shape of the stepped portion 10S and the relationship between the extension direction of the stepped portion 10S and the orientation of the liquid crystal director, the contact angle θa of the first alignment film 410 is preferably 1° or more and 40° or less, and more preferably 7° or more and 15° or less. By adopting this configuration, the pre-tilt angle is suppressed, sufficient transmittance is obtained, and a liquid crystal display device 1 with sufficient thermal stability can be realized.

[0095] The average thickness of the first alignment film 410 is preferably 20 nm or more and 300 nm or less, more preferably 35 nm or more and 250 nm or less, and even more preferably 50 nm or more and 200 nm or less. By adopting this configuration, high transmittance can be obtained while maintaining good alignment control and suppressing light leakage when the light is not illuminated.

[0096] Methods for aligning the first alignment film 410 include methods such as severing polymer chains in a certain direction of the alignment film by irradiation with polarized ultraviolet light (decomposition-type photoalignment method), generating a cis-trans isomerization reaction in the photofunctional groups in the alignment film by irradiation with polarized ultraviolet light (isomerization-type photoalignment method), and rubbing the surface of the alignment film with a napped cloth to increase the proportion of polymer chains on the surface aligned in a certain direction (rubbing alignment method).

[0097] The first alignment film 410 is preferably a photo-alignment film that has been subjected to alignment treatment by polarized ultraviolet irradiation. This configuration allows for effective alignment treatment of the first alignment film 410 provided on the first substrate 100 having a stepped portion 10S. For example, the first alignment film 410 can be a photodegradable polyimide-based alignment film such as the RB series manufactured by Nissan Chemical Corporation.

[0098] The second orientation layer 420 is the same as the first orientation layer 410.

[0099] In a plan view, the angle α between the orientation direction (reference orientation direction) 301A and the third direction 13D of the liquid crystal molecule 300L located near the first alignment film 410 and in the center of the aperture 100E2X, when no voltage is applied, is greater than 0° and less than 90°.

[0100] The central part of an opening is the area where the central part of the opening in the longitudinal direction (a region with a certain range) and the central part of the opening in the width direction (a direction that forms a 90° angle with the longitudinal direction) overlap. The central part of the opening in the longitudinal direction is, for example, the central region of the three regions obtained by dividing the opening into three equal parts in the longitudinal direction. The central part of the opening in the width direction is, for example, the central region of the three regions obtained by dividing the opening into three equal parts in the width direction.

[0101] The orientation direction of liquid crystal molecules in the voltage-free state can be determined as follows. Since the alignment film (for example, an alignment film using a commonly used heat-resistant polymer) has a phase difference in the orientation direction of the liquid crystal molecules, the direction of the phase difference of the alignment film measured by a micropolarization measuring device (for example, a micropolarization spectrophotometer (TFM-120AFT-PC manufactured by Oak Seisakusho)) can be determined as the orientation direction of the liquid crystal molecules in the voltage-free state. If the phase difference of the alignment film is minute and it is difficult to determine the direction of the phase difference of the alignment film, polarized light having a polarization axis that makes a 90° angle with respect to the transmission axis of the polarizer from the direction of the alignment film can be incident on a laminate comprising the alignment film, a liquid crystal layer containing liquid crystal molecules, and a polarizer in this order, and the direction showing the minimum transmittance can be determined as the orientation direction of the liquid crystal molecules in the voltage-free state.

[0102] The parameter P represented by the above formula (1) is preferably 0.074 or higher. By adopting this configuration, a decrease in the contrast of the liquid crystal display device 1 can be suppressed, and light leakage can be suppressed.

[0103] Preferably, the pre-tilt angle of the liquid crystal molecules 300L located near the first alignment film 410 is between 0° and 3°. This configuration allows for sufficient brightness while keeping power consumption down. If the pre-tilt angle exceeds 3°, the transmittance may decrease in the lateral electric field display mode.

[0104] The taper angle β of the stepped portion 10S is preferably 60° or more and 90° or less. By adopting this configuration, the transmittance can be increased and the movable range of the liquid crystal molecules 300L can be expanded. On the other hand, making the stepped portion 10S gentler (for example, making the taper angle β greater than 0° and less than 60°) will widen the light-shielding area and widen the opening 100E2X of the second electrode 100E2, which will lead to a decrease in transmittance and a reduction in the movable range of the liquid crystal molecules 300L.

[0105] In a plan view, the orientation direction 301A of the liquid crystal molecules 300L located near the first alignment film 410 and in the center of the aperture 100E2X, when no voltage is applied, is preferably parallel or perpendicular to the first direction 11D. By adopting this configuration, the decrease in contrast of the liquid crystal display device 1 can be further suppressed.

[0106] The liquid crystal molecules 300L have positive dielectric anisotropy, and in a plan view, the orientation direction 301A of the liquid crystal molecules 300L located near the first alignment film 410 and in the center of the aperture 100E2X, under no applied voltage, is preferably orthogonal to the first direction 11D, with an angle α of 3° or more and 45° or less. By adopting this configuration, the reduction in contrast can be effectively suppressed.

[0107] When angle α is 0°, no light leakage occurs regardless of the surface adsorption force of the first alignment film 410. On the other hand, when angle α exceeds 45°, although there are no problems with the response characteristics, only slight in-plane switching of liquid crystal molecules occurs, which may reduce transmittance.

[0108] In a plan view, the orientation direction of the liquid crystal molecules 300L located near the second substrate 200 and in the center of the aperture 100E2X is preferably orthogonal to the first direction 11D when no voltage is applied. By adopting this configuration, the decrease in contrast of the liquid crystal display device 1 can be further suppressed.

[0109] The liquid crystal display device 1 comprises a gate driver connected to the gate line 120L, a source driver connected to the source line 150L, ​​and a controller connected to the gate driver and the source driver. The gate driver sequentially supplies scanning signals to the gate line 120L based on control by the controller. The source driver supplies data signals to the source line 150L based on control by the controller at the timing when the nonlinear element 100T enters a voltage-applied state due to the scanning signal.

[0110] Each pixel electrode is set to a potential corresponding to the data signal supplied via the corresponding nonlinear element 100T, generating a fringe electric field between the common electrode and the pixel electrode, causing the liquid crystal molecules 300L of the liquid crystal layer 300 to rotate. In this way, the magnitude of the voltage applied between the common electrode and the pixel electrode is controlled, changing the retardation of the liquid crystal layer 300 and controlling the transmission or opacity of light. The liquid crystal display device 1 of this embodiment is a liquid crystal display device in FFS (Fringe Field Switching) mode.

[0111] (Embodiment 2) In this embodiment, we will mainly describe the features specific to this embodiment, and will omit explanations of content that overlaps with Embodiment 1 described above. Figure 11 is a schematic plan view of a liquid crystal display device according to Embodiment 2. This embodiment is substantially the same as Embodiment 1, except that the dielectric anisotropy of the liquid crystal molecules 300L is different. The liquid crystal molecules 300L in the liquid crystal display device 1 of Embodiment 1 have positive dielectric anisotropy, but the liquid crystal molecules 300L in this embodiment have negative dielectric anisotropy. By adopting this configuration, it is possible to suppress the decrease in contrast of the liquid crystal display device 1.

[0112] The liquid crystal molecules 300L have negative dielectric anisotropy. As shown in Figure 11, in a plan view, the orientation direction 301A of the liquid crystal molecules 300L located near the first alignment film 410 and in the center of the aperture 100E2X is parallel to the first direction 11D when no voltage is applied, and the angle α is preferably between 45° and 87°. This configuration effectively suppresses the decrease in contrast and improves transmittance.

[0113] In a plan view, the orientation direction of the liquid crystal molecules 300L located near the second substrate 200 and in the center of the aperture 100E2X is preferably parallel to the first direction 11D when no voltage is applied. By adopting this configuration, the decrease in contrast of the liquid crystal display device 1 can be further suppressed.

[0114] (Modification 1 of Embodiments 1 and 2) Figure 12 is a schematic plan view of a liquid crystal display device according to modification 1 of embodiments 1 and 2. The light-shielding film 100M may be provided in a grid pattern superimposed on the gate line 120L and the source line 150L, ​​as shown in Figure 12.

[0115] (Modification 2 of Embodiments 1 and 2) In embodiments 1 and 2 described above, the second direction 12D is orthogonal to the first direction 11D, which corresponds to the row direction. However, the second direction 12D does not have to be orthogonal to the first direction 11D (i.e., it may be inclined with respect to the column direction).

[0116] Figure 13 is a schematic plan view of a liquid crystal display device according to a modified example 2 of embodiments 1 and 2. As shown in Figure 13, the second direction 12D is inclined with respect to the column direction (up and down direction in the figure). The first direction 11D of this modified example corresponds to the row direction, similar to embodiments 1 and 2. The angle between the first direction 11D and the second direction 12D is preferably 70° or more and 95° or less, preferably 75° or more and 92° or less, and more preferably 80° or more and 90° or less. By adopting this configuration, it is possible to improve the aperture ratio of the pixels 10P.

[0117] In this modified example, the source wire 150L has a zigzag shape with a bend near the gate electrode in order to align the inclination direction of the opening 100E2X. In this modified example, when focusing on a part of the source wire 150L, ​​it extends in a direction inclined with respect to the column direction as shown in Figure 13, but the source wire 150L as a whole extends along the column direction. That is, the direction from one end to the other in the longitudinal direction of the source wire 150L is along the column direction.

[0118] Since the thickness of the source electrode (source wire 150L) is, for example, 300 nm or more and 550 nm or less, the effect of the step of the source electrode remains even after forming the color filter layer 170 and the planarization film 180. However, by using the configuration of this modified example, the display contrast can be improved.

[0119] The effects of the present invention will be explained below with reference to examples, comparative examples, and reference examples, but the present invention is not limited to these examples.

[0120] (Examples 1-4) Liquid crystal display devices 1 of Examples 1 to 4, corresponding to the liquid crystal display device 1 of Embodiment 1, were fabricated. The resolution of the liquid crystal display devices 1 of Examples 1 to 4 was 1400 ppi. The size of each pixel 1P was 18 μm square, and the size of each image element 10P was 6 μm × 18 μm. It was equipped with an electrode slit (aperture 100E2X) and a light-shielding film 100M to prevent oblique color mixing.

[0121] A gate line 120L was formed on the first support substrate 110, followed by the formation of a gate insulating layer (first insulating layer 130) and a thin-film transistor (nonlinear element 100T), and then a source line 150L was formed. The source line 150L also functioned as a light-shielding film between pixels 10P.

[0122] Next, a color filter layer 170 having multiple color filters (red color filter 170R, blue color filter 170B, and green color filter 170G) was formed on the source line 150L using a colored organic resist. Of the multiple color filters, two adjacent color filters in the row direction were formed almost flush and continuously connected near the center in the width direction of the source line 150L. Each color filter was formed continuously in the column direction, straddling the gate line 120L. A planarization film 180, which is an organic planarization film, was provided on the liquid crystal layer 300 side of the color filter layer 170. By forming the planarization film 180 on the color filter layer 170, flatness could be ensured.

[0123] Next, a through-hole (contact hole) 10CH1 for electrically connecting the pixel electrode (first electrode 100E1) and the drain electrode 150D of the thin-film transistor was formed by penetrating the color filter layer 170 and the planarization film 180.

[0124] To perform display in FFS mode, a first electrode 100E1 (pixel electrode), an insulating layer 100F, and a second electrode 100E2 (common electrode) were formed on it. Next, a light-shielding film 100M was formed to fabricate the first substrate 100. Furthermore, a first alignment film 410 was formed on the light-shielding film 100M. The first alignment films 410 in Examples 1 to 4 were the following alignment films A to D, respectively.

[0125] Alignment film A was a horizontal polyimide photoalignment film, alignment film B was a horizontal polyimide photoalignment film with a different photoreaction type from alignment film A, alignment film C was a horizontal polyimide rubbing alignment film, and alignment film D was a horizontal polysiloxane photoalignment film. Alignment film A and alignment film B differed in the irradiation wavelength during the photoalignment treatment; alignment film A was treated with irradiation in the deep ultraviolet wavelength range, while alignment film B was treated with irradiation in the ultraviolet wavelength range.

[0126] A horizontal polyimide photo-aligned film is a horizontally aligned film containing a polymer with polyimide as its main chain, which is oriented by light irradiation. A horizontal polyimide rubbing-aligned film is a horizontally aligned film containing a polymer with polyimide as its main chain, which is oriented by rubbing. A horizontal polysiloxane photo-aligned film is a horizontally aligned film containing a polymer with polysiloxane as its main chain, which is oriented by light irradiation.

[0127] Here, the second electrode 100E2 is provided with a slit (opening 100E2X) that, in a plan view, is inclined at 15° clockwise from a direction perpendicular to the lateral direction of the panel's outer shape (specifically, the direction 11DV perpendicular to the first direction 11D; vertical direction in the figure). The direction perpendicular to the first direction refers to the direction that forms a 90° angle with respect to the first direction. That is, the angle between the first direction 11D and the third direction 13D was 75°. Furthermore, in order to suppress interference with the slit, a light-shielding film 100M was formed with its main sides (longitudinal direction) arranged in the same direction.

[0128] Alignment films A, B, and D were photo-alignment films in which liquid crystal molecules 300L were aligned perpendicular to the transmitted polarized light upon irradiation with polarized ultraviolet light. Alignment film C was a rubbing-alignment film in which liquid crystal molecules 300L were aligned by rubbing with a rubbing cloth or the like. In a plan view, the first alignment film 410 (first substrate 100) was subjected to an alignment treatment such that the alignment direction 301A of the liquid crystal molecules 300L located near the first alignment film 410 and in the center of the aperture 100E2X, under no applied voltage, was perpendicular to the lateral direction of the panel outline (specifically, the direction 11DV perpendicular to the first direction 11D). That is, the angle between the first direction 11D and the alignment direction 301A was 90°.

[0129] Based on the above, in the liquid crystal display devices 1 of Examples 1 to 4, the orientation direction 301A was perpendicular to the first direction 11D, and the angle α was 15°.

[0130] Next, a second substrate 200 was fabricated by forming a second substrate-side light-shielding film 20BM on the second support substrate 210, extending in the direction of the gate line extension (first direction 11D) between the outer frame of the display screen and each pixel 10P. Furthermore, a second alignment film 420 was formed on the second substrate-side light-shielding film 20BM, and the second alignment film 420 was subjected to an alignment treatment so that, in a plan view, the orientation direction of the liquid crystal molecules 300L located near the second alignment film 420 (second substrate 200) and in the center of the opening 100E2X, when no voltage is applied, is oriented in a direction 11DV perpendicular to the first direction 11D. Here, the second alignment film 420 in Examples 1 to 4 were alignment films A to D, respectively.

[0131] A first substrate 100, on which a first alignment film 410 is provided, and a second substrate 200, on which a second alignment film 420 is provided, are placed opposite each other so that the two alignment films face each other, and a liquid crystal layer 300 containing liquid crystal molecules 300L having positive dielectric anisotropy is sandwiched between the two alignment films and bonded together.

[0132] Furthermore, a first polarizing plate 510 was placed on the side of the first substrate 100 opposite to the liquid crystal layer 300, and a second polarizing plate 520 was placed on the side of the second substrate 200 opposite to the liquid crystal layer to obtain a liquid crystal panel. The polarization axis of the first polarizing plate 510 was parallel to the first direction 11D, and the polarization axes of the first polarizing plate 510 and the second polarizing plate 520 were orthogonal to each other.

[0133] Furthermore, the drivers (source driver and gate driver) and drive system circuits were connected to the liquid crystal panel, and a backlight was added to create a liquid crystal display device.

[0134] When the liquid crystal displays of Examples 1 to 4 were observed using a scanning electron microscope (SEM), stepped sections were observed as shown in Figure 14. Figure 14 is an example of a scanning electron microscope image of the liquid crystal displays of Examples 1 to 4.

[0135] (Examples 5 to 8) Liquid crystal display devices 1 of Examples 5 to 8, corresponding to the liquid crystal display device 1 of Embodiment 2, were fabricated. Except for differences in the dielectric anisotropy of the liquid crystal molecules 300L and the orientation processing directions of the first alignment film 410 and the second alignment film 420, the liquid crystal display devices 1 of Examples 5 to 8 were fabricated in the same manner as those of Examples 1 to 4.

[0136] The liquid crystal molecules 300L in the liquid crystal display devices 1 of Examples 5 to 8 had negative dielectric anisotropy.

[0137] In Examples 5 to 8, the first alignment film 410 (first substrate 100) was subjected to an alignment treatment such that, in a plan view, the alignment direction 301A of the liquid crystal molecules 300L located near the first alignment film 410 and in the center of the aperture 100E2X was parallel to the lateral direction of the panel outline (specifically, parallel to the first direction 11D) when no voltage was applied. That is, the angle between the first direction 11D and the alignment direction 301A was 0°. In the liquid crystal display devices 1 of Examples 5 to 8, the alignment direction 301A was parallel to the first direction 11D, and the angle α was 75°.

[0138] In Examples 5 to 8, the second alignment film 420 (second substrate 200) was subjected to an orientation treatment such that, in a plan view, the orientation direction of the liquid crystal molecules 300L located near the second alignment film 420 and in the center of the aperture 100E2X was parallel to the first direction 11D when no voltage was applied.

[0139] (Comparative Example 1) A liquid crystal display device of Comparative Example 1 was fabricated. The liquid crystal display device of Comparative Example 1 had the same configuration as the liquid crystal display device of Example 1, except that the first and second alignment layers were composed of alignment layer E. Alignment layer E was a vertical polyimide rubbing alignment layer. The alignment layer E was subjected to a rubbing treatment using a rubbing cloth so that the alignment direction 301A was the same as in Examples 1 to 4. A vertical polyimide rubbing alignment layer is an alignment layer that contains a polymer having polyimide as its main chain and aligns liquid crystal molecules vertically during the non-alignment treatment.

[0140] (Comparative Example 2) A liquid crystal display device of Comparative Example 2 was fabricated by changing the conditions in Example 7 as shown in Table 2 below.

[0141] (Results from Examples 1-8 and Comparative Examples 1-2) The contrast of the liquid crystal displays in Examples 1 to 8 and Comparative Examples 1 to 2 was measured, and the presence or absence of light leakage was checked. The contrast was determined by dividing the brightness of the liquid crystal display when displaying white by the brightness of the display when displaying black. Light leakage was confirmed by observing the liquid crystal display with a black display using an optical microscope. The results are shown in Tables 1 and 2 below.

[0142] [Table 1]

[0143] [Table 2]

[0144] As shown in Table 1 above, in Examples 1 to 4, where the parameter P represented by formula (1) was 0.77 or less, a contrast of 100 or more was achieved. On the other hand, in Comparative Example 1, where the parameter P represented by formula (1) was greater than 0.77, the contrast was less than 100.

[0145] As shown in Table 2 above, in Examples 5 to 8, where the parameter P represented by formula (1) was 0.77 or less, a contrast of 100 or more was achieved. On the other hand, in Comparative Example 2, where the parameter P represented by formula (1) was greater than 0.77, the contrast was less than 100.

[0146] Furthermore, in Examples 1 to 3, where the parameter P represented by the above formula (1) was 0.074 or higher, light leakage was suppressed. On the other hand, in Example 4, where the parameter P was less than 0.074, light leakage occurred.

[0147] In Examples 5 to 7, where the parameter P represented by formula (1) above was 0.074 or higher, light leakage was suppressed. On the other hand, in Example 8, where the parameter P was less than 0.074, light leakage occurred.

[0148] The alignment film A used in Examples 1 and 5 was a photo-alignment film with a pre-tilt angle of less than 1°. The liquid crystal display devices 1 in Examples 1 and 5 had no light leakage and a contrast ratio of 500 or higher.

[0149] The alignment film B used in Examples 2 and 6 was a photo-alignment film with a pre-tilt angle of less than 1°. The liquid crystal display devices 1 in Examples 2 and 6, like those in Examples 1 and 5, had no light leakage and a contrast ratio of 500 or higher.

[0150] The alignment film C used in Examples 3 and 7 was a rubbing alignment film with a pre-tilt angle of 3°. The liquid crystal display devices 1 of Examples 3 and 7 had no light leakage and ensured a contrast ratio of 300 or higher. Due to the higher pre-tilt angle, the liquid crystal display devices 1 of Examples 3 and 7 had lower contrast than Examples 1 and 5, which used alignment film A, and Examples 2 and 6, which used alignment film B.

[0151] The alignment film D used in Examples 4 and 8 was a photo-alignment film with a pre-tilt angle of less than 1°. Although there was light leakage in the liquid crystal display devices 1 of Examples 4 and 8, a contrast of 100 or more was ensured.

[0152] The alignment film E used in Comparative Example 1 was a vertical alignment film with a pre-tilt angle of 80° or more. In a transverse electric field cell, the liquid crystal molecules hardly responded at all, resulting in a contrast of only about 10. While a larger pre-tilt angle lowers surface tension and reduces light leakage, in the case of a transverse electric field cell, the contrast is inherently low, making it difficult to obtain sufficient display performance.

[0153] In Comparative Example 2, an alignment film C was used, but the parameter P expressed by the above formula (1) exceeded 0.77, resulting in a contrast of less than 100.

[0154] While embodiments and variations thereof have been described above, this disclosure is not limited to the embodiments and variations thereof, and can be implemented in various forms and variations thereof without departing from its essence. Furthermore, the multiple components disclosed in the embodiments and variations thereof can be modified as appropriate. For example, some components from all the components shown in one embodiment or variation may be added to the components of another embodiment or variation, or some components from all the components shown in one embodiment or variation may be removed from the embodiment or variation.

[0155] Furthermore, the drawings schematically show each component in order to facilitate understanding of the invention, and the thickness, length, number, spacing, etc. of each component shown may differ from the actual dimensions due to the convenience of drawing creation. Also, the configuration of each component shown in the above embodiments is merely an example and is not particularly limiting, and it goes without saying that various modifications are possible within the scope that does not substantially deviate from the effects of this disclosure. [Explanation of symbols]

[0156] 1, 1R: Liquid crystal display device 1P: Pixels 10CH1: Through-hole 10P: Picture element 10PB:Blue picture element 10PG: Green picture element 10PR: Red pigment 10S, 10S1, 10S2: Stepped section 10SD: Extension direction 10SH: Height 10SL1: Lower layer 10SL2: Upper layer 10SX: Front page 10SY:Second side 10SZ:Third side 11D: First direction 11DV: Direction 12D:Second direction 13D: Third direction 20BM: Second substrate side light shielding film 100: First board 100R: Array substrate 100E1: First electrode 100E2: Second electrode 100E2X, 100EXR: Opening 100ER: Electrode 100F: Insulating layer 100M, 100MR: Light shielding film 100T: Nonlinear element 110: First support board 120: Gate wiring layer 120L: Gate Line 130: First insulating layer 150: Source wiring layer 150D: Drain electrode 150L: Source wire 160: Second insulating layer 170, 170 CFR: Color filter layer 170B: Blue color filter 170G: Green color filter 170R: Red color filter 180: Flattening film 200:Second board 210:Second support board 300: Liquid crystal layer 300L: Liquid crystal molecules 301A: Orientation direction (reference orientation direction) 410: First orientation film 420:Second alignment film 500: Spacer 510: First polarizing plate 520:Second polarizing plate R1, R2: area

Claims

1. A first substrate comprising multiple gate lines, multiple source lines, multiple nonlinear elements arranged corresponding to the intersections of each gate line and each source line, a first electrode, and a second electrode, First alignment layer, A liquid crystal layer containing liquid crystal molecules, The second board and the following are provided in order: The aforementioned multiple gate lines extend in the first direction, The plurality of source lines extend in a second direction that intersects the first direction, The first electrode and the second electrode are at least partially opposite each other with an insulating layer in between. One of the first electrode and the second electrode is connected to the source line corresponding to that electrode via a nonlinear element corresponding to that electrode. The second electrode is provided with a longitudinally shaped opening. The first substrate has a stepped portion extending in a third direction on the surface facing the first orientation film, In a plan view, the angle α between the orientation direction of the liquid crystal molecules located near the first alignment film and in the center of the opening, under no applied voltage, and the third direction is greater than 0° and less than 90°. A liquid crystal display device in which the parameter P, expressed by the following formula (1) using the angle α, the taper angle β of the stepped portion, and the contact angle θa of the first orientation film with respect to pure water, is 0.77 or less. [Math 1] (However, if the taper angle β exceeds 90°, β = 90° in equation (1) above.)

2. The liquid crystal display device according to claim 1, wherein the parameter P represented by formula (1) is 0.074 or greater.

3. The liquid crystal display device according to claim 1, wherein the pre-tilt angle of the liquid crystal molecules located near the first alignment film is 0° or more and 3° or less.

4. The liquid crystal display device according to claim 1, wherein the taper angle β of the stepped portion is 60° or more and 90° or less.

5. The liquid crystal display device according to claim 1, wherein, in a plan view, the orientation direction of the liquid crystal molecules located near the first orientation film and in the central part of the opening, in a state where no voltage is applied, is parallel to or perpendicular to the first direction.

6. The liquid crystal molecule has positive dielectric anisotropy, In a plan view, the orientation direction of the liquid crystal molecules located near the first orientation film and in the center of the opening, under no applied voltage, is perpendicular to the first direction. The liquid crystal display device according to claim 1, wherein the angle α is 3° or more and 45° or less.

7. The liquid crystal molecule has negative dielectric anisotropy, In a plan view, the orientation direction of the liquid crystal molecules located near the first orientation film and in the center of the opening, under no applied voltage, is parallel to the first direction. The liquid crystal display device according to claim 1, wherein the angle α is 45° or more and 87° or less.

8. The liquid crystal display device according to claim 1, wherein the stepped portion includes the end of the opening of the second electrode.

9. The first substrate further includes a light-shielding film on the liquid crystal layer side of the second electrode, The liquid crystal display device according to claim 1, wherein the stepped portion includes the end of the light-shielding film.

10. The liquid crystal display device according to claim 9, wherein the stepped portion further includes the end of the opening of the second electrode.

11. The liquid crystal display device according to claim 9, wherein the light-shielding film is a metal film, or a laminate comprising a metal film and an inorganic insulating film.

12. The liquid crystal display device according to claim 1, wherein the alignment film is a photo-alignment film that has been subjected to an alignment treatment by polarized ultraviolet irradiation.

13. The liquid crystal display device according to claim 1, wherein the height of the stepped portion is greater than the average thickness of the first orientation film.

14. The liquid crystal display device according to claim 1, wherein the first substrate further comprises a color filter layer.

15. Furthermore, A first polarizing plate is disposed on the opposite side of the first substrate from the liquid crystal layer and has a first polarizing axis that is parallel to or perpendicular to the first direction, A liquid crystal display device according to any one of claims 1 to 14, comprising: a second polarizing plate disposed on the opposite side of the second substrate from the liquid crystal layer and having a second polarizing axis perpendicular to the first polarizing axis.

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