JP5522424B2 - Horizontal electric field type liquid crystal display device - Google Patents

Description

  The present invention relates to a liquid crystal display device, and more particularly to a horizontal electric field type liquid crystal display device.

  In general, a liquid crystal display (LCD) has features such as thin and light weight and low power consumption.

  In particular, an active matrix liquid crystal display device (AM-LCD), in which individual pixels arranged in a matrix of vertical and horizontal dimensions are driven by active elements, has been recognized as a high-quality flat panel display. As an active element, a thin-film transistor (TFT-LCD) using a thin-film transistor (TFT) is widely used.

  Many active matrix type liquid crystal display devices use the electro-optic effect of twisted nematic (TN) type liquid crystal, and an electric field generally perpendicular to the substrate surface is applied to the liquid crystal sandwiched between two substrates. The image is displayed by applying and displacing the molecules of the liquid crystal. This is called “vertical electric field method”. On the other hand, a “horizontal electric field type” liquid crystal display device that displays an image by displacing liquid crystal molecules in a plane substantially parallel to the substrate surface by an electric field substantially parallel to the substrate surface has also been known. . Various improvements have been made to the horizontal electric field type liquid crystal display device in the same manner as the vertical electric field type, and some examples are as follows.

  Patent Document 1 (U.S. Pat. No. 3,807,831, issued in 1974) discloses a configuration using comb-like electrodes that mesh with each other in a liquid crystal display device of a horizontal electric field type (claim 1, FIG. 1). 1-4, see FIG.

  Patent Document 2 (Japanese Patent Laid-Open No. 56-091277) uses an interdigitated comb-like electrode similar to Patent Document 1 in an active matrix liquid crystal display device using the electro-optic effect of a TN liquid crystal. Thus, a technique for reducing the parasitic capacitance between the common electrode and the drain bus line or the parasitic capacitance between the common electrode and the gate bus line is disclosed (claims 2, 2, 7). 9-13).

  Patent Document 3 (Japanese Patent Laid-Open No. 7-036058) discloses a technique for realizing a lateral electric field mode in an active matrix liquid crystal display device using TFTs. In this technique, the common electrode and the video signal electrode or the common electrode and the liquid crystal drive electrode are formed in different layers via an insulating film, and the planar shape of the common electrode or the liquid crystal drive electrode is a ring shape, a cross shape, or a T shape. It is formed into a shape such as a mold, a square shape, an E shape, or a ladder shape (see claims 1 and 5 and FIGS. 1 to 23).

  Patent Document 4 (Japanese Patent Application Laid-Open No. 2002-323706) discloses a pixel electrode and a common electrode (both comb-shaped) for generating a lateral electric field for driving a liquid crystal, for driving individual pixels. A configuration is disclosed in which an insulating layer is interposed above a bus line (data line) that supplies a signal to an active element (that is, at a position closer to the liquid crystal layer) (Claim 1, First Embodiment, FIG. 1-2). According to this configuration, since the common electrode can be formed so as to cover the bus line and an electric field from the bus line can be shielded, display defects due to vertical crosstalk can be prevented, and the common electrode can be prevented. The aperture ratio can be improved by forming a transparent conductive material.

  FIG. 11 is a diagram for explaining an example of the configuration of a conventional general horizontal electric field type active matrix liquid crystal display device. 11A is a plan view thereof, FIG. 11B is a cross-sectional view taken along the line AA ′ in FIG. 11A, and FIG. 11C is a cross-sectional view taken along line BB in FIG. It is sectional drawing along a line. FIGS. 12A, 12B, 12C, and 12D are plan views showing the main part of the manufacturing process of the liquid crystal display device. Each of these figures shows only one pixel region.

  In this liquid crystal display device, as shown in FIGS. 11 (a) and 12 (b), a plurality of gate bus lines 55 extending in the horizontal (left / right) direction of the figure and the vertical (vertical) direction of the figure. Pixel regions are respectively formed in rectangular regions surrounded by a plurality of extending drain bus lines 56, and a plurality of pixels are arranged in a matrix as a whole. The plurality of common bus lines 53 are formed so as to extend in the horizontal direction in the drawing, similarly to the gate bus lines 55. At each intersection of the gate bus line 55 and the drain bus line 56, a thin film transistor (TFT) 45 is formed corresponding to each pixel. The drain electrode 41, the source electrode 42, and the semiconductor film 43 of the thin film transistor 45 are each formed in the pattern (shape) shown in FIG.

  The pixel electrode 71 and the common electrode 72 that generate a liquid crystal driving electric field each have a comb-like portion (a thin band-like portion protruding into each pixel region) that meshes with each other. Here, the comb-like portions of the pixel electrode 71 are two, and the comb-like portion of the common electrode 72 is one. As shown in FIG. 11B, the pixel electrode 71 is electrically connected to the source electrode 42 of the thin film transistor 45 through the contact hole 61 that penetrates the organic interlayer film 60 and the protective insulating film 59, and the common electrode 72 is The common bus line 53 is electrically connected through a contact hole 62 that penetrates the organic interlayer film 60, the protective insulating film 59, and the interlayer insulating film 57. A part of the source electrode 42 of the thin film transistor 45 is overlapped with the common bus line 53 through the interlayer insulating film 57, and a storage capacitor for the pixel region is formed by the overlapped portion.

  The cross-sectional structure of this conventional liquid crystal display device is as shown in FIGS. 11B and 11C, and is formed by joining and integrating an active matrix substrate and a counter substrate with a liquid crystal interposed therebetween.

  The active matrix substrate includes a transparent glass substrate 11 and a common bus line 53, a gate bus line 55, a drain bus line 56, a thin film transistor 45, a pixel electrode 71, and a common electrode 72 formed on the inner surface of the glass substrate 11. Have. The common bus line 53 and the gate bus line 55 are directly formed on the inner surface of the glass substrate 11, and they are covered with an interlayer insulating film 57. The drain electrode 41, the source electrode 42, the semiconductor film 43, and the drain bus line 56 of the thin film transistor 45 are formed on the interlayer insulating film 57. Therefore, the common bus line 53 and the gate bus line 55 are electrically insulated from the drain electrode 41, the source electrode 42, the semiconductor film 43, and the drain bus line 56 by the interlayer insulating film 57. These structures formed on the glass substrate 11 are covered with a protective insulating film 59 except for the contact holes 61 and 62. The level difference caused by the contact holes 61 and 62 is flattened by the organic interlayer film 60 formed on the protective insulating film 59. The pixel electrode 71 and the common electrode 72 are formed on the organic interlayer film 60. As described above, the pixel electrode 71 is electrically connected to the source electrode 42 through the contact hole 61, and the common electrode 72 is electrically connected to the common bus line 53 through the contact hole 62. In addition, sectional drawing of FIG.11 (b) and (c) is a typical figure, and does not reproduce an actual level | step difference structure faithfully.

  The surface of the active matrix substrate having the above configuration (the surface on which the pixel electrode 71 and the common electrode 72 are formed) is covered with an alignment film 31 made of an organic polymer film. The surface of the alignment film 31 is subjected to an alignment process for directing the initial direction of the liquid crystal molecules 21 in a desired direction (see the arrow in FIG. 11A).

  On the other hand, the counter substrate (color filter substrate) includes a transparent glass substrate 12 and red (R) / green (G) / blue (corresponding to each pixel region formed on the inner surface of the glass substrate 12. B) a color filter (not shown) composed of the three primary colors, and a light-shielding black matrix (not shown) formed outside the area corresponding to each pixel area. The color filter and the black matrix are covered with an acrylic overcoat film (not shown). Columnar spacers (not shown) for controlling the distance between the active matrix substrate and the counter substrate are formed on the inner surface of the overcoat film. The inner surface of the overcoat film is covered with an alignment film 32 made of an organic polymer film. The surface of the alignment film 32 is subjected to an alignment treatment for directing the initial direction of the liquid crystal molecules 21 in a desired direction (see the arrow in FIG. 11A).

  The active matrix substrate and the counter substrate having the above-described configuration are opposed to each other with the surfaces on which the alignment film 31 and the alignment film 32 are formed facing each other, and are overlapped at a predetermined interval. Liquid crystal 20 is introduced into the gap between the two substrates, and the periphery of both substrates is sealed with a sealing material (not shown) to confine the liquid crystal 20. A pair of polarizing plates (not shown) are arranged on the outer surfaces of both substrates.

  As described above, the surfaces of the alignment film 31 and the alignment film 32 are uniformly aligned so that the liquid crystal molecules 21 are aligned in parallel along a predetermined direction when there is no electric field. The pixel electrode 71 and the common electrode 72 are inclined 15 degrees clockwise with respect to the direction in which the comb-like portions extend (the vertical direction in FIG. 11A).

  The directions of the transmission axes of the pair of polarizing plates are orthogonal to each other, and one transmission axis of the pair of polarizing plates is the initial alignment direction of the uniformly aligned liquid crystal (alignment direction when no electric field is applied) ).

  Next, a manufacturing process of the conventional liquid crystal display device shown in FIG. 11 will be described with reference to FIG.

  The active matrix substrate is manufactured as follows. First, by forming a chromium (Cr) film on one surface of the glass substrate 11 and patterning it, a common bus line 53 and a gate bus line 55 having a shape as shown in FIG. 12A are formed. Is done. Thereafter, an interlayer insulating film 57 made of silicon nitride (SiNx) is formed over the entire surface of the glass substrate 11 so as to cover the common bus line 53 and the gate bus line 55. Subsequently, on the interlayer insulating film 57, the semiconductor film 43 of the thin film transistor (usually an amorphous silicon (a-Si) film) is overlapped with the corresponding gate bus line 55 via the interlayer insulating film 57. It is formed in an island pattern. Further, by forming a Cr film on the interlayer insulating film 57 and then patterning it, the drain bus line 56, the drain electrode 41, and the source electrode 42 are formed (see FIG. 12B). Thereafter, on the interlayer insulating film 57, a protective insulating film 59 made of SiNx and an organic interlayer film 60 made of a photosensitive acrylic resin are formed in this order so as to cover these structures. Subsequently, a rectangular contact hole 61 that penetrates the protective insulating film 59 and the organic interlayer film 60 and a rectangular contact hole 62 that penetrates the interlayer insulating film 57, the protective insulating film 59, and the organic interlayer film 60 are formed ( (Refer FIG.12 (c)). A pixel electrode 71 and a common electrode 72 are formed on the organic interlayer film 60 by forming an ITO (Indium Tin Oxide) film, which is a transparent electrode material, on the organic interlayer film 60 and then patterning the ITO film. The The pixel electrode 71 is in contact with the source electrode 42 through the contact hole 61. The common electrode 72 contacts the common bus line 53 through the contact hole 62 (see FIG. 12D and FIG. 11B). Thus, an active matrix substrate is manufactured.

  The counter substrate (color filter substrate) is manufactured as follows. First, a color filter and a light-shielding black matrix (both not shown) are formed on one surface of the glass substrate 12, and then overcoated so as to cover the color filter and the black matrix over the entire surface of the glass substrate 12. A film (not shown) is formed. Then, columnar spacers (not shown) are formed on the overcoat film. Thus, the counter substrate is manufactured.

  Alignment films 31 and 32 made of polyimide are formed on the surfaces of the active matrix substrate and the counter substrate manufactured as described above, respectively. Thereafter, the surfaces of the alignment films 31 and 32 are uniformly processed. Subsequently, the two substrates are overlapped with each other at a constant interval (for example, about 4.5 μm), and then the peripheral edges of both substrates are sealed with a sealing material except for the liquid crystal injection hole. Then, after a predetermined nematic liquid crystal (for example, nematic liquid crystal having a refractive index anisotropy of 0.067) is injected into the gap between the two substrates from the liquid crystal injection hole in the vacuum chamber, the liquid crystal injection hole Is closed. After the two substrates are bonded and integrated in this way, a polarizing plate (not shown) is bonded to the outer surfaces of both substrates, thereby completing the conventional liquid crystal display device having the configuration shown in FIG.

  In the conventional lateral electric field type liquid crystal display device as described above, in the vicinity of the tip portions of the comb-like portions of the pixel electrode 71 and the common electrode 72, the normal rotation direction of the liquid crystal molecules when the liquid crystal driving electric field is applied. It is known that a region where liquid crystal molecules rotate in the opposite direction (this region is called “reverse rotation domain”) is generated.

  FIG. 13 is a diagram schematically illustrating the principle that reverse rotation domains occur in the conventional liquid crystal display device shown in FIGS. For ease of explanation, FIG. 13 shows only the pixel electrode 71, the common electrode 72, and the liquid crystal molecules 21, and the liquid crystal drive generated in the pixel region by the comb-like portions of these electrodes 71 and 72. An electric field (line of electric force) is schematically drawn.

  The directions of rotation of the liquid crystal molecules 21 caused by the liquid crystal driving electric field (this rotation occurs in a plane substantially parallel to the active matrix substrate and the counter substrate) are the initial alignment direction of the liquid crystal molecules 21 and the direction of the liquid crystal driving electric field. Therefore, it is “clockwise” in most parts in the pixel region. However, in the vicinity of the tip of the comb-like portion of the pixel electrode 71, the liquid crystal driving electric field is radiated as shown in FIG. 13, so that the liquid crystal molecules are "counterclockwise" in the hatched regions in the figure. Rotate. That is, the area indicated by hatching in the figure is an area in which the liquid crystal molecules rotate “counterclockwise” (that is, a reverse rotation domain).

  As another prior art, in Patent Document 5 (Japanese Patent Laid-Open No. 10-307295), an electrode that generates a transverse electric field is bent, and the driving (rotation) direction of the liquid crystal during the electric field action is determined for each region using the bent portion. And a technique for reducing the coloring of the display in an oblique visual field (see claims 1, 3, 5, and FIGS. 1, 2, 4, and 6).

  For example, the initial alignment direction of the liquid crystal molecules in the first sub-region and the initial alignment direction of the liquid crystal molecules in the second sub-region are the same. It is set as the structure rotated in the reverse rotation direction, maintaining a symmetrical relationship (refer to Claim 3). In this configuration, preferably, the transverse electric field for driving the liquid crystal molecules is generated by the parallel electrode pair, and the electrodes constituting the parallel electrode pair are bent in a V shape (see claim 5). ).

US Pat. No. 3,807,831 JP 56-091277 A Japanese Patent Laid-Open No. 7-036058 Japanese Patent Laid-Open No. 2002-323706 Japanese Patent Laid-Open No. 10-307295

  According to the conventional configuration, the liquid crystal driving electric field is distributed radially in the vicinity of the tip of the comb electrode, and the region in which the liquid crystal rotates in the direction opposite to the predetermined rotation direction due to the relationship with the initial alignment direction of the liquid crystal (reverse) Rotation domain) is formed. Since the liquid crystal drive electric field has a gentle radial shape near the tip of the comb electrode, the dark region (boundary domain) generated between the reverse rotation domain and the normal domain becomes large, and the position is also unstable. is there.

  Therefore, when an external pressure such as a finger press is applied to the display surface, the shape of the reverse rotation domain (or the position of the boundary domain) is not stable and is recognized as a finger press mark even after the external pressure is released. In addition, since the width of the boundary domain becomes large, there is a problem that a loss of panel transmittance is caused. (The reverse rotation domain contributes to the panel transmittance, but the boundary domain remains dark even when white is displayed (when voltage is applied).)

  The present invention has been made in view of the above problems, and its main object is to accurately fix the position where the reverse rotation domain is generated, and a lateral electric field method that is superior in image quality and reliability than the conventional one. A liquid crystal display device is provided.

  To achieve the above object, the present invention provides a pair of substrates disposed opposite to each other, a liquid crystal layer sandwiched between the substrates, and a pair of liquid crystals formed on one or both opposing sides of the substrate. And at least one of the pair of liquid crystal drive electrodes has at least one comb-shaped portion, and the tip of the comb-shaped portion A reverse rotation domain stabilizing electrode that overlaps with the comb-shaped portion via an insulating film is disposed before the portion and / or the base end portion, and a part of the reverse rotation domain stabilizing electrode is formed in the comb-tooth shape. The protrusion has a protrusion protruding from the portion, and the planar shape when the tip and / or the base end of the comb-shaped portion and the protrusion of the reverse rotation domain stabilizing electrode are regarded as one piece is substantially L It has a letter-shaped branch shape.

  Due to the electrode shape characteristics as described above, it is possible to define the electric field distribution generated between the tip of the comb electrode and the electrode facing it, and the boundary between the reverse rotation domain generated in the region and the normal domain Can be fixed.

  Therefore, the reverse rotation domain generated in the vicinity of the tip of the comb electrode is stabilized. Therefore, the shape of the reverse rotation domain is not deformed by an external pressure such as finger pressing, and finger pressing marks are hardly left. In addition, the dark domain (boundary domain) generated at the boundary between the reverse rotation domain and the normal domain can be controlled in a compact manner. As a result, the transmittance as a display element is improved, and the luminance is increased or the power consumption is reduced. Can be realized.

  According to the horizontal electric field type liquid crystal display device of the present invention, by adopting the reverse rotation domain fixing structure having a branching shape, the position where the reverse rotation domain is generated can be accurately fixed. An effect is obtained that a liquid crystal display device with excellent reliability can be obtained.

  In the lateral electric field type liquid crystal display device of the present invention, the tip of the comb electrode has a branch shape at the portion where the reverse rotation domain is generated in the vicinity of the tip of the comb electrode, and the branch shape is when the liquid crystal is driven. It is characterized by surrounding the reverse rotation domain. The specific configuration will be described below with reference to the drawings.

  FIG. 1 is a diagram for explaining the configuration of a lateral electric field type active matrix liquid crystal display device according to a first embodiment of the present invention, in which FIG. 1 (a) is a plan view, and FIG. 1 (b) is FIG. FIG. 1A is a cross-sectional view taken along line AA ′ in FIG. 1A, and FIG. 1C is a cross-sectional view taken along line BB ′ in FIG. FIGS. 2A, 2B, 2C, and 2D are plan views showing the main part of the manufacturing process of the liquid crystal display device. Each of these figures shows only one pixel region.

  In this liquid crystal display device, as shown in FIGS. 1 (a) and 2 (b), a plurality of gate bus lines 55 extending in the horizontal (left / right) direction in the figure and the vertical (vertical) direction in both figures. Each pixel region is formed in a rectangular region surrounded by a plurality of drain bus lines 56 extending in the direction, and a plurality of pixels are arranged in a matrix as a whole. A plurality of common bus lines 53 are formed so as to extend in the horizontal direction in both drawings, like the gate bus lines 55. A thin film transistor (TFT) 45 is formed at each intersection of the gate bus line 55 and the drain bus line 56 so as to correspond to each pixel. The drain electrode 41, the source electrode 42, and the semiconductor film 43 of the thin film transistor 45 are each formed in the pattern (shape) shown in FIG.

  The pixel electrode 71 and the common electrode 72 that generate the liquid crystal driving electric field have shapes as shown in FIG. That is, the common electrode 72 includes a frame-shaped main portion formed so as to surround the pixel region, and one comb tooth extending from the center of the upper side portion toward the lower side portion in the internal space of the main portion. (A thin band-like portion protruding downward into the pixel region). The main part of the common electrode 72 is formed integrally with the main part of a common electrode (not shown) for other pixel regions. The lower end of the comb-like portion of the common electrode 72 is not in contact with the lower side portion. On the other hand, the pixel electrode 71 is disposed in a rectangular internal space of the common electrode 72, and has a rectangular plate-shaped main portion arranged so as to overlap the source electrode 42, and the common electrode 72 from both ends of the upper side of the main portion. And two comb-like portions (thin strip-like portions protruding upward in the pixel region) respectively extending toward the upper side portion. These comb-like portions are arranged on both sides of the comb-like portion of the common electrode 72, and are therefore laid out so as to mesh with each other within the pixel region. The interval between the comb-like portion of the common electrode 72 and the comb-like portion of the pixel electrode 71 on both sides thereof is substantially equal to the interval between the pixel electrode 71 and the main portion of the common electrode 72.

  The pixel electrode 71 (main part) is electrically connected to the source electrode 42 of the thin film transistor 45 through a contact hole 61 penetrating the organic interlayer film 60 and the protective insulating film 59, and the common electrode 72 (main part) is The organic interlayer film 60, the protective insulating film 59, and the interlayer insulating film 57 are electrically connected to the common bus line 53 through a contact hole 62 that passes through the organic interlayer film 60. The connection mode is as shown in FIG. A part of the source electrode 42 of the thin film transistor 45 is overlapped with the common bus line 53 through the interlayer insulating film 57, and a storage capacitor for the pixel region is formed by the overlapped portion.

  Each comb-like portion of the pixel electrode 71 has a branched shape at the tip. That is, it has a projection part branched from the front of the tip part of each comb tooth-like part, and the plane shape which combined each tip part and the projection part by branching has made the shape of an abbreviated L character. The protrusions due to these branch shapes have a liquid crystal driving electric field generated in the vicinity of the tip portion when the branch shape does not exist on both sides of each tip portion (see FIG. 13). It is provided only on the side of the region causing the liquid crystal rotation in the reverse direction.

  Similarly, the comb-teeth portion of the common electrode 72 has a branched shape at the tip. That is, it has a projection part branched from the front of the tip part of each comb tooth-like part, and the plane shape which combined each tip part and the projection part by branching has made the shape of an abbreviated L character. The protrusions due to these branching shapes rotate the liquid crystal driving electric field generated in the vicinity of the tip part on both sides of each tip part in the direction opposite to the normal liquid crystal rotation direction. It is provided only on the side of the region that causes

  Furthermore, one of the two comb-tooth shaped portions of the pixel electrode 71 (the right side in the drawing) has a branched shape at the base end portion. That is, it has a branched protruding portion in front of the base end portion of the comb-like portion, and the planar shape of the base end portion and the protruding portion having the branched shape is substantially L-shaped. The projecting portions due to these branch shapes are provided only in regions where the liquid crystal driving electric field generated when such a branch shape does not exist causes liquid crystal rotation in the direction opposite to the normal liquid crystal rotation direction. The other of the two comb-tooth-shaped portions of the pixel electrode 71 (the left side in the figure) is not provided with a projecting portion having a branched shape because it does not cause liquid crystal rotation in the opposite direction on both sides of the base end portion. .

  As for the base end portion of the comb-like portion of the common electrode 72, the liquid crystal driving electric field causes the liquid crystal rotation in the reverse direction on one side (right side in the figure) of the base end portion. Since the protruding portion branched from the front of the tip portion of the comb-shaped portion is provided, the branched protruding portion is not provided at the base end portion of the comb-shaped portion of the common electrode 72.

  Note that the branch shape in the present invention may or may not have a bifurcated branch symmetrical with respect to the branch start point. In addition, here, one comb-tooth portion of the common electrode 72 and two comb-tooth portions of the pixel electrode 71 are used. However, the number of comb-tooth portions is not limited to the configuration shown in the figure.

  Further, in the drawings for explaining the configuration of the present invention, the planar outline of each electrode is shown linearly and the corners are shown at right angles, but the outline has an oblique direction or a curved side. It may also be a shape with rounded corners. Similarly, the cross-sectional shape of the electrode may be a shape including an inclined side or a curve with respect to the substrate surface.

  The cross-sectional structure of the liquid crystal display device according to the present embodiment is as shown in FIGS. 1B and 1C, in which an active matrix substrate and a counter substrate are joined and integrated with a liquid crystal interposed therebetween. .

  The active matrix substrate includes a transparent glass substrate 11 and a common bus line 53, a gate bus line 55, a drain bus line 56, a thin film transistor 45, a pixel electrode 71, and a common electrode 72 formed on the inner surface of the glass substrate 11. Have. The common bus line 53 and the gate bus line 55 are directly formed on the inner surface of the glass substrate 11, and they are covered with an interlayer insulating film 57. The drain electrode 41, the source electrode 42, the semiconductor film 43, and the drain bus line 56 of the thin film transistor 45 are formed on the interlayer insulating film 57. Therefore, the common bus line 53 and the gate bus line 55 are electrically insulated from the drain electrode 41, the source electrode 42, the semiconductor film 43, and the drain bus line 56 by the interlayer insulating film 57. These structures formed on the glass substrate 11 are covered with a protective insulating film 59 except for the contact holes 61 and 62. The level difference caused by the contact holes 61 and 62 is flattened by the organic interlayer film 60 formed on the protective insulating film 59. The pixel electrode 71 and the common electrode 72 are formed on the organic interlayer film 60. As described above, the pixel electrode 71 is electrically connected to the source electrode 42 through the contact hole 61, and the common electrode 72 is electrically connected to the common bus line 53 through the contact hole 62. 1B and 1C are schematic views and do not faithfully reproduce an actual step structure.

  The surface of the active matrix substrate having the above configuration (the surface on which the pixel electrode 71 and the common electrode 72 are formed) is covered with an alignment film 31 made of an organic polymer film. The surface of the alignment film 31 is subjected to an alignment process for directing the initial direction of the liquid crystal molecules 21 in a desired direction (see the arrow in FIG. 1A).

  On the other hand, the counter substrate is a transparent glass substrate 12 and a color filter (not shown) composed of R, G, and B primary colors formed on the inner surface of the glass substrate 12 in correspondence with each pixel region. And a black matrix for light shielding (not shown) formed outside the area corresponding to each pixel area. The color filter and the black matrix are covered with an acrylic overcoat film (not shown). Columnar spacers (not shown) for controlling the distance between the active matrix substrate and the counter substrate are formed on the inner surface of the overcoat film. The inner surface of the overcoat film is covered with an alignment film 32 made of an organic polymer film. The surface of the alignment film 32 is subjected to an alignment treatment for directing the initial direction of the liquid crystal molecules 21 in a desired direction (see the arrow in FIG. 1A).

  The active matrix substrate and the counter substrate having the above-described configuration are overlapped at a predetermined interval with the surfaces on which the alignment film 31 and the alignment film 32 are formed inside. Liquid crystal 20 is introduced into the gap between the two substrates, and the periphery of both substrates is sealed with a sealing material (not shown) to confine the liquid crystal 20. A pair of polarizing plates (not shown) are arranged on the outer surfaces of both substrates.

  As described above, the surfaces of the alignment film 31 and the alignment film 32 are uniformly aligned so that the liquid crystal molecules 21 are aligned in parallel along a predetermined direction when there is no electric field. The pixel electrode 71 and the common electrode 72 are inclined 15 degrees clockwise with respect to the direction in which the comb-like portions extend (vertical direction in FIG. 1A).

  The directions of the transmission axes of the pair of polarizing plates are orthogonal to each other, and one transmission axis of the pair of polarizing plates is the initial alignment direction of the uniformly aligned liquid crystal (alignment direction when no electric field is applied) ).

  Note that the initial alignment direction (alignment processing direction) of the liquid crystal molecules 21 is with respect to the direction in which the comb-like portion of the pixel electrode 71 and the comb-like portion of the common electrode 72 extend (vertical direction in FIG. 1A). The direction is inclined 15 degrees clockwise (see the inclined bold arrow in the figure). For this reason, when a liquid crystal driving electric field is applied to the liquid crystal molecules 21, the liquid crystal molecules 21 are set to rotate clockwise (see the curved bold arrows in the figure) in the main part in the pixel region. ing.

  Next, the manufacturing process of the liquid crystal display device of this embodiment shown in FIG. 1 will be described with reference to FIG.

  The active matrix substrate is manufactured as follows. First, by forming a Cr film on one surface of the glass substrate 11 and patterning it, a common bus line 53 and a gate bus line 55 having a shape as shown in FIG. . Thereafter, an interlayer insulating film 57 made of SiNx is formed over the entire surface of the glass substrate 11 so as to cover the common bus line 53 and the gate bus line 55. Subsequently, an island-shaped pattern is formed on the interlayer insulating film 57 so that the semiconductor film 43 of the thin film transistor (usually an a-Si film) overlaps the corresponding gate bus line 55 with the interlayer insulating film 57 interposed therebetween. Formed with. Further, by forming a Cr film on the interlayer insulating film 57 and then patterning it, the drain bus line 56, the drain electrode 41, and the source electrode 42 are simultaneously formed (see FIG. 2B). Thereafter, on the interlayer insulating film 57, a protective insulating film 59 made of SiNx and an organic interlayer film 60 made of a photosensitive acrylic resin are formed in this order so as to cover these structures. Subsequently, a rectangular contact hole 61 that penetrates the protective insulating film 59 and the organic interlayer film 60 and a rectangular contact hole 62 that penetrates the interlayer insulating film 57, the protective insulating film 59, and the organic interlayer film 60 are formed ( (Refer FIG.2 (c)). A pixel electrode 71 and a common electrode 72 are formed on the organic interlayer film 60 by forming an ITO film as a transparent electrode material on the organic interlayer film 60 and then patterning the ITO film. The pixel electrode 71 is in contact with the source electrode 42 through the contact hole 61. The common electrode 72 contacts the common bus line 53 through the contact hole 62. Thus, an active matrix substrate is manufactured.

  The counter substrate (color filter substrate) is manufactured as follows. First, a color filter and a light-shielding black matrix (both not shown) are formed on one surface of the glass substrate 12, and then overcoated so as to cover the color filter and the black matrix over the entire surface of the glass substrate 12. A film (not shown) is formed. Then, columnar spacers (not shown) are formed on the overcoat film. Thus, the counter substrate is manufactured.

  Alignment films 31 and 32 made of polyimide are formed on the surfaces of the active matrix substrate and the counter substrate manufactured as described above, respectively. Thereafter, the surfaces of the alignment films 31 and 32 are uniformly processed. Subsequently, the two substrates are overlapped with each other at a constant interval (for example, about 4.5 μm), and then the peripheral edges of both substrates are sealed with a sealing material except for the liquid crystal injection hole. Then, after a predetermined nematic liquid crystal (for example, p-type nematic liquid crystal having a refractive index anisotropy of 0.067) is injected into the gap between the two substrates from the liquid crystal injection hole in the vacuum chamber, the liquid crystal injection The hole is closed. After the substrates are bonded and integrated in this way, a polarizing plate (not shown) is bonded to the outer surfaces of the substrates, whereby the liquid crystal display device of the first embodiment shown in FIG. 1 is completed.

  An n-type nematic liquid crystal can also be used. In that case, it is only necessary to change only the orientation processing direction by 90 degrees with respect to the aforementioned angle, with the same configuration as described above except for the orientation processing direction (initial orientation direction). Hereinafter, a case where a p-type nematic liquid crystal is used will be described.

  Next, the operation of the liquid crystal display device of the first embodiment having the above configuration will be described with reference to FIGS. FIG. 3 shows a state in which a liquid crystal driving electric field is generated by applying a voltage between the pixel electrode 71 and the common electrode 72 on the upper side of the pixel region in FIG. It is a figure shown by expressing an electric force line with a broken line. Further, the rotation direction of the liquid crystal molecules 21 by the action of the liquid crystal driving electric field is indicated by an arc-shaped arrow. FIG. 4 is a view similarly showing the lower side of the pixel region in FIG.

  As described above, the initial alignment direction of the liquid crystal 20 is clockwise with respect to the direction in which the comb-like portion of the pixel electrode 71 and the comb-like portion of the common electrode 72 extend (vertical direction in FIG. 1A). Therefore, when a liquid crystal driving electric field is applied, the liquid crystal molecules 21 rotate clockwise in a normal region.

  On the other hand, as shown in FIG. 3 and FIG. 4, a substantially L-shaped shape formed by a projecting portion and a tip portion having a branched shape provided in a comb-like portion of each pixel electrode 71, and a common electrode facing each other 72 (the two regions in FIG. 3) surrounded by 72 (the main portion and the proximal end portion of the comb-shaped portion), and the projecting portion and the distal end portion of the branch shape provided on the comb-shaped portion of the common electrode 72 A region (region from the center of FIG. 4) surrounded by the substantially L-shaped shape to be formed and the opposing pixel electrode 71 (the main portion and the base end portion of the comb-shaped portion), and the comb of the pixel electrode 71 A region surrounded by a substantially L-shaped shape formed by a projecting portion having a branch shape provided near the base end portion of the tooth-like portion and the base end portion, and a main portion of the common electrode 72 facing (FIG. In the region from the right side of FIG. 4, the liquid crystal driving electric field is generated by being inclined clockwise with respect to the horizontal direction of the figure. Because, liquid crystal molecules rotate in a counterclockwise direction, to generate a reverse rotation domain.

  A boundary domain is formed between the reverse rotation domain and the normal region, and it becomes dark even when a voltage is applied. However, due to the action of the branch shape provided in the pixel electrode 71 and the common electrode 72, such a boundary domain is formed. Border domains are contained in small areas. This is greatly different so that the tilt direction of the liquid crystal driving electric field is reversed on both sides of the branching projection as a boundary, so that clockwise rotation and counterclockwise rotation on each side are respectively This is because it is caused by strong torque.

  In other words, the position where the reverse rotation domain and the boundary domain are generated can be accurately fixed to the position intended in advance by the action of the branch shape provided in the pixel electrode 71 and the common electrode 72.

  Therefore, the reverse rotation domain generated in the vicinity of the tip of the comb electrode is stabilized. Therefore, the shape of the reverse rotation domain is not deformed by an external pressure such as finger pressing, and finger pressing marks are hardly left. In addition, the dark domain (boundary domain) generated at the boundary between the reverse rotation domain and the normal domain can be controlled in a compact manner. As a result, the transmittance as a display element is improved, and the luminance is increased or the power consumption is reduced. Can be realized.

  Hereinafter, among the effects described above, effects relating to the improvement of the transmittance will be supplementarily described with examples. The configuration of this example was applied to a liquid crystal display device having a size of 10.4 type and a pixel number of 640 pixels (× RGB) × 480 pixels, and the light transmittance of the panel portion was measured to be 7.9%. The transmittance was obtained.

  On the other hand, when the configuration of the comb electrode without a branch shape described in the conventional example was used without using the configuration of this example, it was 7.5%. This difference corresponds to an improvement effect due to compact control of the boundary domain by the configuration of the present embodiment. In addition, referring to the prior application of the inventor of the present application (Japanese Patent Laid-Open No. 10-26767), in a case where the generation of the reverse rotation domain is completely suppressed by the sawtooth electrode shape, the panel of 7.2% It became the transmittance. That is, it was confirmed that the panel transmittance can be improved by adopting the configuration of this example.

  FIG. 5 shows a liquid crystal display device according to a second embodiment of the present invention. The configuration of the liquid crystal display device of this embodiment is obtained by bending the pixel electrode and the common electrode that generate a liquid crystal driving electric field with reference to the technique described in Patent Document 5 described above, and using the bent portion to act the liquid crystal driving electric field. This is different from the configuration of the first embodiment in that the driving (rotation) direction of the liquid crystal molecules is intentionally different for each region, and the other points are the same. Therefore, the same reference numerals as those in the first embodiment are given to elements having the same configurations as those in the first embodiment, and the description thereof is omitted.

  In the second embodiment, as shown in FIG. 5, the pixel electrode 71 and the common electrode 72 that generate the liquid crystal driving electric field have comb-tooth portions that mesh with each other, as in the configuration of the first embodiment. However, the comb-like portion is bent in a substantially V shape with a straight line L extending in the left-right direction in the figure as a boundary at a substantially central portion of the pixel region. Corresponding to this, the drain bus line 56 extending in the vertical direction in the figure is also bent in a substantially V shape. Therefore, the shape of the pixel region is also bent into a substantially V shape.

  The pixel region is divided into a first sub region 1 above the straight line L and a second sub region 2 below the straight line L at the bent position. The pixel electrode 71 and the common electrode 72 are bent at a predetermined angle counterclockwise in the first sub-region 1 with respect to the vertical direction in the figure, and bent at the same angle as the first sub-region 1 in the second sub-region 2 clockwise. doing. The alignment treatment direction of the liquid crystal molecules 21 is set so that the liquid crystal molecules 21 are aligned in parallel in the vertical direction of the figure (see the bold arrow in FIG. 5) when there is no electric field. An angle (offset angle) in a direction in which the pixel electrode 71 and the common electrode 72 extend in each region is preferably a value in a range of about ± 10 degrees to ± 25 degrees with respect to the alignment processing direction, for example, ± 15 degrees ( The first sub-region 1 can be set to about 15 degrees counterclockwise, and the second sub-region 2 can be set to about 15 degrees clockwise). (The larger the offset angle, the lower the threshold voltage for driving the liquid crystal, but the peak voltage for obtaining the maximum transmittance increases. That is, the transmittance curve with respect to the applied voltage becomes gentler. (The curve becomes steeper, and the larger the offset angle, the easier it is to fix the boundary position of the liquid crystal domain at the bent portion of the comb electrode stably.)

  The liquid crystal driving electric field when the liquid crystal driving voltage is applied is generated in a direction inclined slightly counterclockwise with respect to the horizontal direction (the direction of the straight line L) in the main region of the first sub-region 1, In the main area of the sub-area 2, it occurs in a direction slightly tilted clockwise with respect to the horizontal direction in the figure. Therefore, the liquid crystal molecules 21 that are uniformly aligned along the vertical direction in the figure when no electric field is applied are mainly clockwise in the first subregion 1 and mainly counterclockwise in the second subregion 2 due to the liquid crystal driving electric field. Each rotates around. As described above, since the rotation directions of the liquid crystal molecules in the first sub-region 1 and the second sub-region 2 are different from each other, there is an advantage that an effect that the coloring of the display accompanying the change in the viewing angle can be suppressed can be obtained.

  Also in the second embodiment, similarly to the configuration of the first embodiment, the pixel electrode 71 and the common electrode 72 are provided with a branched shape. As shown in FIG. 6 and FIG. 7, the position of the reverse rotation domain and the boundary domain in each of the first sub-region 1 and the second sub-region 2 is accurately set to the intended position by the action of these branch shapes. It becomes possible to fix to. Therefore, the reverse rotation domain generated in the vicinity of the tip of the comb electrode is stabilized. Therefore, the shape of the reverse rotation domain is not deformed by an external pressure such as finger pressing, and finger pressing marks are hardly left. In addition, the dark domain (boundary domain) generated at the boundary between the reverse rotation domain and the normal domain can be controlled in a compact manner. As a result, the transmittance as a display element is improved, and the luminance is increased or the power consumption is reduced. Can be realized.

  In the second embodiment, the branch shape at the tips of the comb-shaped portions of the pixel electrode 71 and the common electrode 72 is a branch shape perpendicular to the direction parallel to the initial alignment direction of the liquid crystal molecules. In addition, a combination with an electrode that generates a liquid crystal driving electric field facing the branch-shaped portion (that is, a part of one of the pixel electrode 71 and the common electrode 72 that is branched) , A combination of the other electrode facing this part and the corresponding part) forms a planar shape combining a pair of key brackets. By adopting such a shape, an electric field inclined substantially uniformly with respect to the initial alignment direction of the liquid crystal can be generated, and the reverse rotation domain as described above can be stably fixed. Here, the ratio of the short side to the long side when this “shape combining a pair of brackets” is regarded as a rectangle is about 2: 1 to 3: 1, and the long side is the initial alignment direction of the liquid crystal. , The degree of rotation of the liquid crystal molecules in that region is approximately the same as the degree of rotation of the liquid crystal molecules in the region where the comb electrodes (pixel electrode 71 and common electrode 72) extend in parallel. (That is, the transmittance curves with respect to the applied voltage are almost the same.) Therefore, it is possible to efficiently contribute to light transmission, which is convenient. When the ratio is smaller than the relationship of 2: 1 to 3: 1, the inclination of the liquid crystal driving electric field in this region increases, that is, the direction in which the comb electrodes extend and the initial alignment direction of the liquid crystal molecules. This is a characteristic corresponding to the case where the angle between them (offset angle) is large. That is, the threshold voltage for driving the liquid crystal decreases, and the peak voltage for obtaining the maximum transmittance increases. The transmittance curve with respect to the applied voltage becomes gentle. On the contrary, when the ratio is large, the inclination of the liquid crystal driving electric field in this region is small, that is, the characteristic corresponds to that when the offset angle is small. As described above, it is most preferable that the ratio is about 2: 1 to 3: 1, but it is also possible to set the range of about 1: 1 to about 4: 1.

  As described above, in this embodiment, the extending directions of the two tip portions constituting the branch shape of the tip of the comb-shaped portion are respectively directions perpendicular to the direction parallel to the initial alignment direction of the liquid crystal molecules. This relationship generates a liquid crystal driving electric field inclined in a preferred direction. However, even if the relationship between the extending direction of these tips and the initial alignment direction of the liquid crystal molecules is not exactly this, It does not matter even if it is shifted. However, it is desirable that each relationship be less than the offset angle (15 degrees in the above example) between the direction in which the main portion of the comb-shaped portion extends and the initial alignment direction of the liquid crystal molecules.

  FIG. 8 shows the characteristics of the third embodiment of the present invention. The branch shape of the tip portion of the comb electrode may be a shape as shown in FIG. Further, in addition to the shape as shown in FIG. 8, various shapes such as a shape in which a projecting portion due to branching is bent or curved are possible. As the shape, the shape of the second embodiment is preferable. This is because the light transmittance in the reverse rotation region is higher in the case of the shape of the second embodiment.

  9 and 10 show the features of the fourth embodiment of the present invention. In this embodiment, the tip of the comb electrode itself is not branched, but it has a reverse rotation domain stabilizing electrode having an overlapping portion with the tip of the comb electrode, and this reverse rotation domain stabilization The planar shape when the integrated electrode and the comb-shaped electrode are regarded as one body has the same characteristics as the shape of the comb-shaped electrode of the second embodiment described above. The reverse rotation domain stabilization electrode having the overlapping portion with the pixel electrode 71 is formed of a Cr film in the same layer as the drain bus line 56, and the reverse rotation domain stabilization electrode having the overlapping portion with the common electrode 72 is the gate bus line 55. The common bus line 53 and the same layer of Cr film are formed. Since the reverse rotation domain stabilizing electrode has substantially the same potential as the superimposed comb electrode due to the action of the capacitance formed in the overlapping portion with the comb electrode, the effect of the present invention can be obtained even in such a configuration. it can.

  Examples of utilization of the present invention include a horizontal electric field type liquid crystal display device, a computer monitor using the liquid crystal display device, a liquid crystal television, a mobile phone terminal, a GPS terminal, a car navigation system, a game machine, a bank / convenience store terminal, a medical diagnosis Examples thereof include an apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the structure of the active-matrix type liquid crystal display device of a horizontal electric field system which concerns on 1st Example of this invention, (a) is a top view, (b) is along the AA 'line of (a). (C) is sectional drawing which followed the BB 'line of (a). It is a principal part top view which shows the manufacturing process of the active-matrix-type liquid crystal display device of a horizontal electric field system which concerns on 1st Example of this invention. It is a figure which shows a mode when a voltage is applied between a pixel electrode and a common electrode, and the liquid crystal drive electric field is generated about the upper side of the pixel area | region in Fig.1 (a). It is a figure which shows a mode when a voltage is applied between a pixel electrode and a common electrode, and the liquid crystal drive electric field is generated about the lower side of the pixel area | region in Fig.1 (a). It is a top view explaining the structure of the active-matrix type liquid crystal display device of a horizontal electric field system which concerns on 2nd Example of this invention. FIG. 6 is a diagram illustrating a state when a liquid crystal driving electric field is generated by applying a voltage between a pixel electrode and a common electrode on the upper side of the pixel region in FIG. 5. FIG. 6 is a diagram illustrating a state when a liquid crystal driving electric field is generated by applying a voltage between a pixel electrode and a common electrode on the lower side of the pixel region in FIG. 5. When the liquid crystal driving electric field is generated by applying a voltage between the pixel electrode and the common electrode on the upper side of the pixel region of the horizontal electric field type active matrix liquid crystal display device according to the third embodiment of the present invention. It is a figure which shows a mode. When a liquid crystal driving electric field is generated by applying a voltage between the pixel electrode and the common electrode on the upper side of the pixel region of the active matrix type liquid crystal display device of the horizontal electric field type according to the fourth embodiment of the present invention. It is a figure which shows a mode. When the liquid crystal driving electric field is generated by applying a voltage between the pixel electrode and the common electrode on the lower side of the pixel region of the horizontal electric field type active matrix liquid crystal display device according to the fourth embodiment of the present invention. It is a figure which shows a mode. It is a figure explaining an example of a structure of the conventional active electric field type liquid crystal display device of a general horizontal electric field system, (a) is a top view, (b) is the cross section along the AA 'line of (a). FIG. 4C is a sectional view taken along line BB ′ in FIG. FIG. 12 is a plan view of relevant parts showing a manufacturing process of the liquid crystal display device of FIG. 11. FIG. 12 is a diagram showing a state when a liquid crystal driving electric field is generated by applying a voltage between a pixel electrode and a common electrode on the upper side of the pixel region in FIG. 11.

DESCRIPTION OF SYMBOLS 1 1st sub-region 2 2nd sub-region 11, 12 Glass substrate 20 Liquid crystal 21 Liquid crystal molecule 31, 32 Alignment film 41 Drain electrode 42 Source electrode 43 Semiconductor film 45 Thin film transistor (TFT)
53 common bus line 55 gate bus line 56 drain bus line 57 interlayer insulation film 59 protective insulation film 60 organic interlayer film 61, 62 contact hole 71 pixel electrode 72 common electrode

Claims (14)

A lateral electric field system having at least a pair of substrates disposed opposite to each other, a liquid crystal layer sandwiched between the substrates, and a pair of liquid crystal drive electrodes formed on one or both opposing sides of the substrate In liquid crystal display devices,
At least one of the pair of liquid crystal drive electrodes has at least one comb-shaped portion,
In front of the distal end portion and / or the proximal end portion of the comb-tooth shaped portion, a reverse rotation domain stabilizing electrode that is superimposed on the comb tooth-shaped portion via an insulating film is disposed,
A part of the reverse rotation domain stabilizing electrode has a protrusion protruding from the comb-shaped portion,
The planar shape when the tip end portion and / or the base end portion of the comb-tooth shaped portion and the protrusion of the reverse rotation domain stabilizing electrode are regarded as an integral L-shaped branch shape. A liquid crystal display device. The liquid crystal display device according to claim 1.
The extending direction of the distal end portion and / or the proximal end portion substantially coincides with the initial alignment direction of the liquid crystal layer,
2. A liquid crystal display device, wherein a direction in which the protrusion extends is substantially perpendicular to an initial alignment direction of the liquid crystal layer. The liquid crystal display device according to claim 2.
A liquid crystal display device, wherein a direction in which a portion excluding the tip and / or base end of the comb-shaped portion extends is an oblique direction with respect to an initial alignment direction of the liquid crystal layer. The liquid crystal display device according to claim 2 or 3,
The extending direction of the portion excluding the distal end portion and / or the proximal end portion of the comb-tooth shaped portion forms an obtuse angle with respect to each of the extending direction of the distal end portion and / or the proximal end portion and the extending direction of the projection portion. A liquid crystal display device characterized by the above. The liquid crystal display device according to any one of claims 1 to 4,
A liquid crystal display device characterized in that the branched shape surrounds a reverse rotation domain when driving liquid crystal. The liquid crystal display device according to any one of claims 1 to 5,
The rotation direction of the liquid crystal molecules of the liquid crystal layer when driving the liquid crystal in the region sandwiched between the branched shapes is the rotation direction of the liquid crystal molecules of the liquid crystal layer when driving the liquid crystals in the region outside the region sandwiched between the branched shapes. A liquid crystal display device characterized in that the liquid crystal display device is configured in the reverse direction. The liquid crystal display device according to any one of claims 1 to 6,
When the rotation direction of the liquid crystal molecules of the liquid crystal layer in the region opposite to the tip of the region on both sides with the projection as a boundary is the forward direction, the projection is regarded as the boundary. The rotation direction of the liquid crystal molecules in the liquid crystal layer when driving the liquid crystal in the region on the tip side is the reverse direction,
The liquid crystal display device characterized in that a region in which the liquid crystal molecules rotate in the reverse direction is smaller than a region in which the liquid crystal molecules rotate in the forward direction. The liquid crystal display device according to any one of claims 1 to 7,
When the rotation direction of the liquid crystal molecules of the liquid crystal layer when driving the liquid crystal in the region opposite to the base end portion in the region on both sides with the projection as a boundary is the forward direction, the projection is defined as the boundary. The rotation direction of the liquid crystal molecules in the liquid crystal layer when the liquid crystal is driven in the region on the base end side is the reverse direction,
The liquid crystal display device characterized in that a region in which the liquid crystal molecules rotate in the reverse direction is smaller than a region in which the liquid crystal molecules rotate in the forward direction. The liquid crystal display device according to any one of claims 1 to 8,
The liquid crystal display device, wherein the comb-shaped portion is bent into a substantially V shape at a bent portion at a substantially central portion of each pixel region. The liquid crystal display device according to claim 9.
The extending direction of the comb-shaped portion on each side of the bent portion and the initial alignment direction of the liquid crystal molecules of the liquid crystal layer are different from each other by a predetermined angle,
The liquid crystal display device is characterized in that the relationship between the angles is symmetrical with each other on both sides of the bent portion. The liquid crystal display device according to any one of claims 1 to 10,
The shape of the combination of a part of one of the pair of liquid crystal driving electrodes that is branched at one part and the part of the other electrode facing the one electrode is a pair of key brackets. A liquid crystal display device characterized in that the shape is a combination. The liquid crystal display device according to claim 11.
A liquid crystal display device characterized in that the ratio of the length of the long side to the short side is 1: 1 to 4: 1 when the shape formed by combining the pair of key brackets is regarded as a rectangle. The liquid crystal display device according to claim 12.
A ratio of the length of the long side to the short side is 2: 1 to 3: 1. The liquid crystal display device according to claim 12 or 13,
A liquid crystal display device, characterized in that the direction of the long side when the shape combining the pair of key brackets is regarded as a rectangle coincides with the initial alignment direction of the liquid crystal.

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