JP2012226216A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device of high display quality.SOLUTION: The liquid crystal display device includes: a display unit DYP including a plurality of display pixels PX which include openings OP surrounded with a light shielding part BM and are arranged like a matrix; and a light control element 50 of which portions of the same characteristic in a second direction D2 are periodically arranged in a first direction D1 to give parallax in the first direction D1. Openings OP arranged in the first row and the second row adjacent to each other in the second direction D2 have shapes symmetrical with respect to the first direction D1, and each of the openings OP arranged in the first row has a pair of first end sides forming a first angle A1 with the first direction D1, and each of the openings OP arranged in the second row has a pair of second end sides forming a second angle A2 with the first direction D1, and an alignment film 10A is subjected to rubbing treatment in a direction forming a third angle A3 with the first direction D1, and a difference between the third angle A3 and the first angle A1 is equal to or more than 10° and equal to or less than 45°.

Description

  Embodiments described herein relate generally to a liquid crystal display device.

  In recent years, various types of 3D video display devices have been proposed. Among them, the integral imaging system (hereinafter referred to as II system) controls the parallax in the horizontal direction by arranging a slit or a lenticular lens sheet on a liquid crystal display device. Therefore, the II-type liquid crystal display device has attracted attention because it has a high degree of freedom in the viewpoint position and can be easily stereoscopically viewed without polarized glasses.

  The II-type liquid crystal display device can handle a high-resolution liquid crystal display device, but the aperture pattern of the liquid crystal display unit arranged in a matrix and the periodic structure of the lens pitch interfere optically, and moire occurs. Various solutions have been proposed to avoid this. For example, a method has been proposed in which the liquid crystal openings are tilted in different directions in pixels in odd rows and even rows to break periodicity and eliminate moire.

JP 2008-249887 A

  However, when the design of the pixel opening as described above is applied to a liquid crystal display device, when the alignment direction of the liquid crystal, that is, the rubbing direction and the direction of the pixel opening substantially coincide, the vicinity of the boundary between the opening and the light shielding portion As a result, the alignment of the liquid crystal becomes unstable and the liquid crystal may be reversed. When the liquid crystal is reversed near the boundary between the opening and the light-shielding portion, when viewing from a diagonal direction with respect to the display portion DYP during black display, the light appears to be bright in the region where the liquid crystal is reversed, and unevenness and afterimage In some cases, the display quality deteriorated.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a liquid crystal display device with good display quality.

  According to the embodiment, an array substrate, a counter substrate disposed to face the array substrate, a liquid crystal layer sandwiched between the array substrate and the counter substrate, and the liquid crystal layer are in contact with each other. A pair of alignment films disposed on the main surfaces of the array substrate and the counter substrate and subjected to rubbing, and a display unit including a plurality of display pixels arranged in a matrix including openings surrounded by a light shielding unit, A light beam control element that is disposed opposite to the display unit and periodically arranges the same characteristics in the second direction in a first direction substantially orthogonal to the second direction to provide parallax in the first direction; The openings arranged in the first and second rows adjacent to each other in the second direction have a target shape with respect to the first direction and are arranged in the first row. The opening has a first direction and a first direction. The opening arranged in the second row includes a pair of second end sides that form a second angle with the first direction, and the array substrate has a main edge of the array substrate. The alignment film disposed on the surface is rubbed in a direction that forms a third angle with the first direction, and a difference between the third angle and the first angle is 10 ° to 45 °. Is provided.

It is a figure which shows roughly the example of 1 structure of the liquid crystal display device of embodiment. It is a figure for demonstrating one structural example of the opening part of the display pixel of the liquid crystal display device of embodiment. It is a figure for demonstrating an example of the relationship between the opening part of the liquid crystal display device of embodiment, and a rubbing direction. It is a figure which shows an example of the transmittance | permeability with respect to the position of the cross section in line AA when the rubbing direction on the array substrate side is 60 ° and the rubbing direction on the counter substrate side is 120 °. It is a figure which shows an example of the transmittance | permeability with respect to the position of the cross section in line BB when the rubbing direction on the array substrate side is 60 ° and the rubbing direction on the counter substrate side is 120 °. It is a figure which shows an example of the transmittance | permeability with respect to the position of the cross section in line AA when the rubbing direction by the side of an array substrate is 45 degrees and the rubbing direction by the side of a counter substrate is 135 degrees. It is a figure which shows an example of the transmittance | permeability with respect to the position of the cross section in line BB when the rubbing direction by the side of an array substrate is 45 degrees and the rubbing direction by the side of an opposing substrate is 135 degrees.

  Hereinafter, a liquid crystal display device according to an embodiment will be described with reference to the drawings. In this embodiment, the angle will be described assuming that the 9 o'clock direction of the watch is 0 °, the 12 o'clock direction is 90 °, and the 3 o'clock direction is 180 ° toward the paper surface. The horizontal direction D1 is a direction substantially parallel to the direction passing through 9 o'clock and 3 o'clock, and the column direction D2 is a direction substantially parallel to the direction passing through 12 o'clock and 6 o'clock.

  FIG. 1 schematically shows a configuration example of the liquid crystal display device of the present embodiment. The liquid crystal display device according to the present embodiment includes an array substrate 10, a counter substrate 20 disposed opposite to the array substrate 10, a liquid crystal layer LQ sandwiched between the array substrate 10 and the counter substrate 20, and a matrix shape. And a pair of polarizing plates 30 and 40 and a light beam control element 50. In the liquid crystal display device according to the present embodiment, the display unit DYP is normally white with a diagonal of 12 inches and employs a TN (twisted nematic) mode.

  The light beam control element 50 is, for example, a lenticular sheet (cylindrical lens array). In the lenticular sheet, lenses whose cross section in the first direction D1 is convex on the user side are arranged in the first direction (horizontal direction) D1. The light emitted from the display unit DYP is collected by the lens of the lenticular sheet and is visually recognized by the user. Therefore, the user visually recognizes the image of the visual recognition area AR that is enlarged by the lenticular sheet and extends in the second direction (column direction) D2.

  The light beam control element 50 may be a slit array. The slit array includes a plurality of slits (not shown) extending in the second direction D2. The slits of the slit array are periodically arranged in the first direction D1. In the area between the slits, light from the display unit DYP is blocked. The user visually recognizes the light emitted from the display unit DYP that passes through the slits of the slit array. That is, the user visually recognizes the image of the visual recognition area AR extending in the second direction D2 through the slit.

  Each of the light beam control elements 50 changes the image that is seen depending on the position at which the user visually recognizes the display unit DYP in the first direction D1. Therefore, even if the same position of the light beam control element 50 is viewed, different images can be seen depending on the position of the user. The light beam control element 50 provides left and right parallax (horizontal parallax), and lenses or slits having the same characteristics in the second direction D2 are arranged in the first direction D1.

  The array substrate 10 includes a pixel electrode PE disposed in each display pixel PX in the display unit DYP, a scanning line Y (Y1, Y2, Y3,...) Extending along a row in which the pixel electrodes PE are arranged, and a pixel electrode PE. , And a pixel switch SW disposed in the vicinity of a position where the scanning line Y and the signal line X cross each other. The pixel electrode PE is formed of a transparent electrode material such as ITO (Indium Tin Oxide).

  The pixel switch SW includes, for example, a thin film transistor. The thin film transistor includes a semiconductor layer formed of amorphous silicon or polysilicon. The gate electrode of the thin film transistor is electrically connected to the corresponding scanning line Y (or formed integrally). The source electrode of the thin film transistor is electrically connected to the corresponding signal line X (or formed integrally). The drain electrode of the thin film transistor is electrically connected to (or integrally formed with) the corresponding pixel electrode PE.

  The plurality of scanning lines Y are electrically connected to a scanning line driving circuit (not shown) arranged around the display unit DYP. The plurality of signal lines X are electrically connected to a signal line driving circuit (not shown) arranged around the display unit DYP.

  The scanning line driving circuit sequentially drives the plurality of scanning lines Y, closes the pixel switch SW corresponding to each row of the display pixels PX, and conducts between the source electrode and the drain electrode. The signal line driving circuit applies video signals corresponding to the plurality of signal lines X, and applies the video signals to the corresponding pixel electrodes PE via the closed pixel switches SW.

  Around the display portion DYP, various wiring such as wiring for transmitting a control signal to the scanning line driving circuit and the signal line driving circuit and wiring for transmitting a video signal to the signal line driving circuit is routed. It is electrically connected to a connection portion 12 provided at an end portion of the substrate 10. One end of a flexible substrate (not shown) for transmitting / receiving signals to / from the outside can be electrically connected to the connection portion 12 of the array substrate 10. Control signals and video signals from an external signal source are input to the array substrate 10 via a flexible substrate.

  The counter substrate 20 includes a counter electrode CE that faces a plurality of pixel electrodes PE. The counter electrode CE is formed of a transparent conductor such as ITO. A counter voltage is applied to the counter electrode CE by a counter electrode driving circuit (not shown).

  The liquid crystal layer LQ has a thickness (width in the thickness direction D3) of approximately 4 μm, and is sandwiched between the array substrate 10 and the counter substrate 20. The liquid crystal layer LQ includes liquid crystal molecules (not shown) whose alignment state is controlled by the potential difference between the potential of the pixel electrode PE and the potential of the counter electrode CE. The direction of vibration of polarized light transmitted through each display pixel PX is controlled by the alignment state of the liquid crystal molecules.

  A pair of alignment films 10A and 20A are disposed on the surface of the array substrate 10 and the counter substrate 20 that are in contact with the liquid crystal layer LQ. The surfaces of the alignment films 10A and 20A are rubbed in a predetermined direction. In the present embodiment, the rubbing direction DB of the alignment film 10A on the array substrate 10 side is approximately 60 ° (angle A3 shown in FIG. 2) with respect to the horizontal direction D1, and the rubbing direction of the alignment film 20A on the counter substrate 20 side. DA forms approximately 120 ° (angle A4 shown in FIG. 2) with respect to the horizontal direction D1.

  On the main surface of the array substrate 10 opposite to the liquid crystal layer LQ, a polarizing plate 30 having an absorption axis substantially parallel to the angle A3 obtained by rubbing the alignment film 10A is disposed. A polarizing plate 40 having an absorption axis substantially parallel to an angle A4 obtained by rubbing the alignment film 20A is disposed on the main surface of the counter substrate 20 opposite to the liquid crystal layer LQ.

  The absorption axis of the polarizing plate 30 on the array substrate 10 side and the rubbing angle A3 may be positioned substantially orthogonal to each other, and the absorption axis of the polarizing plate 40 on the counter substrate 20 side and the rubbing angle A4 may be positioned substantially orthogonal to each other. .

  In the case of a color display type liquid crystal display device, the plurality of display pixels PX include a plurality of types of color display pixels, for example, a red pixel PXR that displays red (R), a green pixel PXG that displays green (G), and a blue (B). Has a blue pixel PXB. That is, the red pixel PXR includes a red color filter (not shown) that transmits light having a red main wavelength. The green pixel PXG includes a green color filter (not shown) that transmits light having a green main wavelength. The blue pixel PXB includes a blue color filter (not shown) that transmits light having a blue main wavelength. These color filters are arranged on the main surface of the array substrate 10 or the counter substrate 20.

  FIG. 2 shows an example of the relationship between the opening OP of the display pixel PX and the rubbing angles A3 and A4. The red pixel PXR, the green pixel PXG, and the blue pixel PXB are arranged so as to be periodically arranged in the horizontal direction D1 and the same color in the column direction D2.

  On the array substrate 10 or the counter substrate 20, a light shielding portion BM is disposed so as to surround the opening OP of the display pixel PX (PXR, PXG, PXB). The light shielding portion BM includes a resin layer colored in black, for example, and is disposed so as to cover a region between the pixel electrodes PE.

  The shape of the opening OP is different between the Nth row (first row) and the (N + 1) th row (second row) adjacent in the column direction D2. The opening OP in the Nth row and the opening OP in the (N + 1) th row are symmetrical with respect to the horizontal direction D1.

  The opening OP in the Nth row is surrounded by two end sides that extend in the horizontal direction D1 and face each other, and two end sides that face each other at 130 ° (angle A2) with respect to the horizontal direction D1. Yes. The opening OP in the (N + 1) th row is surrounded by two opposite sides extending in the horizontal direction D1 and two opposite sides facing each other at an angle of 50 ° (angle A1) with respect to the horizontal direction D1. It is.

  The sizes of the angles A1 and A2 are examples, and the angle A1 is not limited to the above values as long as the angle A1 is equal to 180 ° minus the angle A2. In this way, the openings OP of the Nth row and the (N + 1) th row are made symmetrical with respect to the horizontal direction D1, and the aperture ratio in the column direction D2 is constant at any position in the horizontal direction D1. Has been.

  FIG. 3 shows the transmittance at a predetermined position inside the light shielding portion BM with respect to the difference (A3−A1) (°) between the angle A1 of the opening and the rubbing angle A3 of the alignment film 10A when black display is performed. An example of the simulation result about (%) is shown.

  In the liquid crystal display device having the above configuration, the rubbing directions DA and DB of the alignment films 10A and 20A were changed, and a simulation of light leakage of each display pixel PX was performed. As shown in FIG. 3, when the difference between the angle A1 of the opening OP in the (N + 1) th row (even-numbered row) and the rubbing angle A3 of the alignment film 10A is around 0 °, the difference is about 3 μm inside the light shielding portion BM. The liquid crystal was aligned with a transmittance of 30% or more. This is thought to be due to the occurrence of a high transmittance due to the reverse of the liquid crystal in the vicinity of the end of the light shielding part BM.

  When the difference between the angle A1 of the opening OP in the even-numbered row and the rubbing angle A3 of the alignment film 10A is gradually increased from this state, the difference (A3-A1) between the angle A1 and the angle A3 is 10 ° or more. Thus, the transmittance of the liquid crystal was reduced to less than 5% at a position of 3 μm inside the light shielding portion BM.

  Note that, when the openings OP adjacent in the column direction D2 are arranged symmetrically with respect to the horizontal direction D1, as in the liquid crystal display device according to the present embodiment, the transmittance in the column direction D2 is always constant. Formed as follows. In this case, if the pitch at which the display pixels PX are arranged is determined, the angles A1 and A2 of the pixel opening OP are uniquely determined. Therefore, it is difficult to change the angles A1 and A2 of the opening OP. Further, if the light shielding portion BM is reduced in order to eliminate the influence of the reverse of the liquid crystal, the transmittance is greatly lowered.

  The inventor of the present application can provide a liquid crystal display device in which the reverse of the liquid crystal does not occur in the vicinity of the end portion of the light shielding portion BM by appropriately designing the rubbing angles A3 and A4 based on the above simulation results. I found it.

  That is, the liquid crystal display device according to the present embodiment is designed so that the difference (A3-A1) between the angle A1 of the opening OP and the rubbing angle A3 is 10 ° or more and 45 ° or less based on the simulation result. Has been.

  Here, when the difference between the angle A1 of the opening OP and the rubbing angle A3 is increased, the capacitance of the wiring such as the signal line X disposed zigzag between the openings OP and extending in the second direction D2 increases, and the pixel electrode It may be difficult to supply a desired video signal to the PE, and the display quality may be deteriorated. Therefore, in this embodiment, in order to avoid an increase in the wiring capacitance as described above, the difference between the angle A1 of the opening OP and the rubbing angle A3 is set to 45 ° or less.

  In FIG. 4A, the rubbing angle A3 of the alignment film 10A on the array substrate 10 side is 60 ° ± 2 °, the rubbing angle A4 of the alignment film 20A on the counter substrate 20 side is 120 ° ± 2 °, and black display is performed. An example of the liquid-crystal transmittance with respect to the position of the cross section in line AA is shown.

  In FIG. 4B, the rubbing angle A3 of the alignment film 10A on the array substrate 10 side is 60 ° ± 2 °, the rubbing angle A4 of the alignment film 20A on the counter substrate 20 side is 120 ° ± 2 °, and black display is performed. An example of the transmittance of the liquid crystal with respect to the position of the cross section along line BB is shown.

  In the TN mode liquid crystal display device, in order to emphasize the symmetry, the rubbing direction DA on the array substrate 10 side and the rubbing direction DB on the counter substrate 20 side are set regardless of the angles A1 and A2 of the opening OP. It is desirable to target the column direction D2.

  As described above, when the rubbing angle A3 of the alignment film 10A is 60 °, the difference (A3-A1) between the angle A1 and the angle A3 is 10 ° (= 60 ° -50 °). At this time, as shown in FIG. 4A and FIG. 4B, in both the odd-numbered openings and the even-numbered openings, the alignment state has a high transmittance due to the reverse of the liquid crystal in the vicinity of the end of the light-shielding portion BM. The part which becomes becomes did not occur. Therefore, even when viewed from an oblique direction toward the display unit DYP, transmitted light leakage due to reverse of the liquid crystal did not occur.

  In FIG. 5A, the rubbing angle A3 on the array substrate 10 side is 45 ° ± 2 °, the rubbing angle A4 on the counter substrate 20 side is 135 ° ± 2 °, and the position of the cross section along the line AA when black is displayed. An example of the transmittance is shown.

  In FIG. 5B, the rubbing angle A3 on the array substrate 10 side is 45 ° ± 2 °, the rubbing angle A4 on the counter substrate 20 side is 135 ° ± 2 °, and the position of the cross section at line BB when black is displayed. An example of the transmittance is shown.

  As described above, when the rubbing angle A3 of the alignment film 10A is 45 °, the difference (A3−A1) between the angle A1 and the angle A3 is −5 ° (= 45 ° -50 °). At this time, as shown in FIG. 5B, when the simulation result of the transmittance distribution for the display pixels PX in the even-numbered rows is seen, light is transmitted because no voltage is applied to the light shielding portion BM, but the opening OP and the light shielding portion BM are transmitted. There is a region where the alignment of the liquid crystal becomes unstable in the vicinity of the boundary, and reverse is likely to occur.

  In the case shown in FIG. 5B, reverse of the liquid crystal occurs, and there is a portion that is in an alignment state with high transmittance due to the reverse of the liquid crystal 3 μm inside from the end of the light shielding portion BM. The portion with the high transmittance depends on the angles A1 and A2 of the opening OP and the rubbing angles A3 and A4, and the influence becomes large when the difference between the two is smaller than a predetermined value. Further, as shown in FIG. 5A, in the odd-numbered-row openings, there was no portion in the vicinity of the end portion of the light-shielding portion BM that had an alignment state with high transmittance due to the reverse of the liquid crystal. In this case, when viewed from an oblique direction toward the display unit DYP, transmitted light is visually recognized during black display, and the display quality may be degraded.

  On the other hand, in the liquid crystal display device according to the present embodiment, the difference between the angle A1 of the opening OP and the rubbing angle A3 of the alignment film 10A is 10 ° or more and 45 ° or less, so in the vicinity of the end of the light shielding portion BM. The alignment of the liquid crystal is not unstable and no reverse occurs.

  Therefore, according to the liquid crystal display device according to the present embodiment, the display pixels PX are arranged at any pitch with respect to the liquid crystal display device having the structure of the pixel opening for three-dimensional display, that is, Regardless of the display pixel PX having an angle of the opening OP, an appropriate rubbing angle is set according to the display pixel PX, and the liquid crystal has excellent display quality without unevenness or afterimage by controlling the orientation of the liquid crystal. A display device can be provided.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DYP ... display unit, LQ ... liquid crystal layer, PX ... display pixel, D1 ... horizontal direction, D2 ... column direction, AR ... viewing area, SL ... slit, PE ... pixel electrode, Y (Y1, Y2, Y3 ...) ... scanning Line, X (X1, X2, X3 ...) ... Signal line, SW ... Pixel switch, CE ... Counter electrode, DB ... Rubbing direction, DA ... Rubbing direction, PXR ... Red pixel, PXG ... Green pixel, PXB ... Blue pixel, OP (OPR, OPG, OPB) ... opening, BM ... light shielding part, A1 ... opening angle (even-numbered rows), A2 ... opening angle (odd-numbered rows), A3 ... rubbing angle (array substrate side), A4 ... rubbing angle (opposite substrate side), 10 ... array substrate, 10A ... alignment film (array substrate side), 20A ... alignment film (opposite substrate side), 12 ... connecting portion, 20 ... counter substrate, 30, 40 ... polarizing plate , 50. Light beam control element.

Claims (6)

An array substrate;
A counter substrate disposed to face the array substrate;
A liquid crystal layer sandwiched between the array substrate and the counter substrate;
A pair of alignment films disposed on the main surface of the array substrate and the counter substrate so as to be in contact with the liquid crystal layer and subjected to a rubbing treatment;
A display unit including a plurality of display pixels arranged in a matrix including an opening surrounded by a light shielding unit;
A light beam control element that is disposed opposite to the display unit and periodically arranges the same characteristics in the second direction in a first direction substantially orthogonal to the second direction to provide parallax in the first direction; Prepared,
The openings arranged in the first row and the second row adjacent to each other in the second direction have a target shape with respect to the first direction,
The opening disposed in the first row includes a pair of first edges forming a first angle with the first direction,
The opening disposed in the second row includes a pair of second end sides that form a second angle with the first direction,
The alignment layer disposed on the main surface of the array substrate is rubbed in a direction that forms a third angle with the first direction,
The liquid crystal display device, wherein a difference between the third angle and the first angle is 10 ° to 45 °.   The liquid crystal display device according to claim 1, wherein the light beam control element is a lenticular sheet.   The liquid crystal display device according to claim 1, wherein the light beam control element is a slit. A first polarizing plate attached to an opposite main surface of the array substrate on which the alignment film is disposed so that an absorption axis is substantially parallel or substantially orthogonal to the third angle;
The main surface of the counter substrate opposite to the alignment film on which the alignment film is disposed is attached so that the absorption axis is substantially parallel or substantially orthogonal to the rubbing direction of the alignment film disposed on the main surface of the counter substrate. A liquid crystal display device according to claim 1, comprising two polarizing plates.   The rubbing direction of the alignment film disposed on the main surface of the array substrate and the rubbing direction of the alignment film disposed on the main surface of the counter substrate are targets with respect to the second direction. The liquid crystal display device according to claim 1.   The liquid crystal display device according to claim 1, wherein the liquid crystal layer includes a TN mode liquid crystal.

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