Liquid crystal display device

Abstract

To provide a liquid crystal display device that enables high resolution while maintaining an aperture ratio. [Solution] A liquid crystal display device comprising: an array substrate having a plurality of pixels arranged in an M x N matrix (where M and N are integers of 2 or more); a plurality of first pixel electrodes provided corresponding to each of the plurality of pixels; and M second pixel electrodes positioned adjacent to each of the M first pixel electrodes in the first column of the plurality of first pixel electrodes on the opposite side in the row direction from the first pixel electrode in the second column; a liquid crystal layer containing liquid crystal molecules; and a control unit that applies a predetermined voltage to the M second pixel electrodes such that, for a pixel in an m x 1 column (where m is any integer between 1 and M), the liquid crystal molecules belonging to that pixel are driven by an electric field formed between the first pixel electrode in the m x 1 column of the plurality of first pixel electrodes and the second pixel electrode adjacent to the first pixel electrode in the m x 1 column of the M second pixel electrodes in the row direction.

Description

[Technical Field]

[0001] The following disclosure relates to liquid crystal display devices. [Background technology]

[0002] In recent years, development of liquid crystal display panels (LCDs for HMDs) for use in head-mounted displays has been progressing. Because LCDs for HMDs require accurate color reproduction even at the edges of the field of view, the display modes mainly used for liquid crystals are those in which liquid crystal molecules move horizontally with respect to the polarization plane, such as in-plane switching (IPS) mode and fringe field switching (FFS) mode. For example, Patent Documents 1 and 2 disclose an example of a conventional IPS mode liquid crystal display device. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2005-37913 [Patent Document 2] Japanese Patent Publication No. 2006-189758 [Overview of the project] [Problems that the invention aims to solve]

[0004] In applications such as LCDs for HMDs, there is a growing demand for higher resolution liquid crystal panels, and in recent years, display resolutions have exceeded 1000 ppi and are approaching 2000 ppi. However, with conventional IPS and FFS modes, it has been difficult to increase the pixel aperture ratio (hereinafter also simply referred to as "aperture ratio") and the maximum transmittance (mode efficiency) for the same aperture area, making it impossible to ensure sufficient transmittance in ultra-high-resolution liquid crystal display devices.

[0005] Figure 1 is a schematic diagram showing the pixel configuration in an IPS mode liquid crystal display device. As shown in the figure, in an IPS mode pixel, the pixel electrode 320 and the common electrode 310 are provided on the same plane. In ultra-high-definition liquid crystal display devices, the width W of the portion of the display area (optical aperture) 300 that is actually used for display (the portion sandwiched between the pixel electrode 320 and the common electrode 310) cannot be made large due to manufacturing precision, making it difficult to ensure transmittance.

[0006] Figure 2 is a schematic diagram showing the pixel configuration in a liquid crystal display device in FFS mode. As shown in the figure, in FFS mode pixels, the pixel electrode (upper electrode) 420 and the common electrode 410 are superimposed three-dimensionally, which is advantageous in terms of processing accuracy compared to IPS mode. However, since the electric field lines E act on the liquid crystal molecules of the display unit 400 through the opening of the pixel electrode 420, the liquid crystal molecules also have an inclination in the thickness direction of the cell, making it difficult to obtain sufficient mode efficiency.

[0007] This invention has been made in view of the above-mentioned circumstances, and aims to provide a liquid crystal display device that can achieve high resolution while ensuring an aperture ratio. [Means for solving the problem]

[0008] (1) One embodiment of the present invention is an array substrate having a plurality of pixels arranged in an M x N matrix (where M and N are integers of 2 or more), a plurality of first pixel electrodes provided corresponding to each of the plurality of pixels, and M second pixel electrodes positioned adjacent to each of the M first pixel electrodes in the first column of the plurality of first pixel electrodes on the opposite side from the first pixel electrode in the second column in the row direction, a liquid crystal layer containing liquid crystal molecules, and for a pixel in m x 1 column (where m is any integer between 1 and M), the first pixel electrode in m x 1 column of the plurality of first pixel electrodes and the M second A liquid crystal display device comprising: a control unit that applies a predetermined voltage to the M second pixel electrodes and applies a voltage based on a video signal to the plurality of first pixel electrodes, such that the liquid crystal molecules belonging to the pixel are driven by an electric field formed between the first pixel electrode in the m row and column 1 of the pixel electrodes and the second pixel electrode adjacent to it in the row direction, and for a pixel in the m row and n columns (where n is any integer between 2 and N), the liquid crystal molecules belonging to the pixel are driven by an electric field formed between the first pixel electrode in the m row and n column and the first pixel electrode in the m row and (n-1) column of the plurality of first pixel electrodes, respectively.

[0009] (2) In addition, one embodiment of the present invention is a liquid crystal display device in which, in addition to the configuration of (1) above, the control unit determines a voltage to be applied to the first pixel electrode of the m row and 1 column based on the grayscale displayed in the m row and 1 column pixel, using the predetermined voltage as a reference, and determines a voltage to be applied to the first pixel electrode of the m row and n column based on the voltage applied to the first pixel electrode of the m row and (n-1) column based on the grayscale displayed in the m row and n column pixel.

[0010] (3) In addition, one embodiment of the present invention, in addition to the configuration of (2) above, the maximum applied voltage to the plurality of first pixel electrodes is A max (V) The minimum applied voltage to the plurality of first pixel electrodes is A min (V) The voltage that realizes the grayscale to be displayed in the m row and n column pixels is B n (V), the voltage applied to the first pixel electrode of the m row (n-1) column is C n-1 (V), the voltage applied to the first pixel electrode of the m row and n column is C nWhen defining (V), the control unit is C n A liquid crystal display device that determines (V) by any one of the following formulas (1) and (2) or any one of the following formulas (3) and (4). Formula (1): C n-1 +B n ≦A max When, C n =C n-1 +B n Formula (2): C n-1 +B n >A max When, C n =C n-1 -B n Formula (3): C n-1 -B n ≧A min When, C n =C n-1 -B n Formula (4): C n-1 -B n <A min When, C n =C n-1 +B n

[0011] (4) Further, in a certain embodiment of the present invention, in addition to the configuration of (2) or (3) above, the control unit reverses the polarity of the predetermined voltage between the positive field and the negative field in one frame to drive the M second pixel electrodes and the first pixel electrode of m rows and 1 column in an alternating manner. A liquid crystal display device.

[0012] (5) Further, in a certain embodiment of the present invention, in addition to the configuration of (3) or (4) above, the control unit determines C n (V) by any one of the formulas (1) and (2) in the positive field in one frame, and determines C n (V) by any one of the formulas (3) and (4) in the negative field in one frame to drive the first pixel electrode of m rows and n columns in an alternating manner. A liquid crystal display device. <##

[0013] (6) Another embodiment of the present invention is a liquid crystal display device in which, in addition to the configuration of (1), (2), (3), (4) or (5) above, a constant DC component is superimposed on the voltage applied to each of the plurality of first pixel electrodes.

[0014] (7) In addition, one embodiment of the present invention is a liquid crystal display device in which, in addition to the configuration of (1), (2), (3), (4), (5) or (6) above, the second pixel electrode has substantially the same shape as the first pixel electrode.

[0015] (8) In addition, one embodiment of the present invention is a liquid crystal display device in which, in addition to the configuration of (1), (2), (3), (4), (5), (6) or (7) above, the first pixel electrode has a linear shape without branched portions.

[0016] (9) In addition, one embodiment of the present invention is a liquid crystal display device in which, in addition to the configuration of (8) above, the array substrate further has a source bus line to which a voltage based on the video signal is supplied, and the angle between the first direction in which the main portion including the central part of the first pixel electrode extends and the direction in which the source bus line extends is 15° or less.

[0017] (10) In addition, one embodiment of the present invention is a liquid crystal display device in which, in addition to the configuration of (8) or (9) above, the array substrate further has a source bus line to which a voltage based on the video signal is supplied, and the first pixel electrode has a main portion that includes its central portion and extends in a first direction, and a bent portion that is connected to at least one end of the main portion in the first direction and extends in a second direction, and the angle between the second direction and the direction in which the source bus line extends is greater than the angle between the first direction and the direction in which the source bus line extends.

[0018] (11) Another embodiment of the present invention is a liquid crystal display device in which, in addition to the configurations of (1), (2), (3), (4), (5), (6), (7), (8), (9) or (10) above, at least one of the first pixel electrode and the second pixel electrode is made of a light-shielding material.

[0019] (12) Another embodiment of the present invention provides an array substrate having a plurality of pixels arranged in an M x N matrix (where M and N are integers of 2 or more), a plurality of first pixel electrodes provided corresponding to each of the plurality of pixels, and M second pixel electrodes positioned adjacent to each of the M first pixel electrodes in the first column of the plurality of first pixel electrodes on the opposite side from the first pixel electrode in the second column in the row direction, a liquid crystal layer containing liquid crystal molecules, and for a pixel in m x 1 column (where m is any integer between 1 and M), the first pixel electrode in the m x 1 column of the plurality of first pixel electrodes and the m row of the M second pixel electrodes A liquid crystal display device comprising: a control unit that applies a voltage to the M second pixel electrodes and applies a voltage based on a video signal to the plurality of first pixel electrodes, wherein the first pixel electrodes have a linear shape without branched portions.

[0020] (13) In addition, one embodiment of the present invention is a liquid crystal display device in which, in addition to the configuration of (12) above, the array substrate further has a source bus line to which a voltage based on the video signal is supplied, and the angle between the first direction in which the main portion including the central part of the first pixel electrode extends and the direction in which the source bus line extends is 15° or less.

[0021] (14) In addition, one embodiment of the present invention is a liquid crystal display device in which, in addition to the configuration of (12) or (13) above, the array substrate further has a source bus line to which a voltage based on the video signal is supplied, and the first pixel electrode has a main portion that includes its central portion and extends in a first direction, and a bent portion that is connected to at least one end of the main portion in the first direction and extends in a second direction, and the angle between the second direction and the direction in which the source bus line extends is greater than the angle between the first direction and the direction in which the source bus line extends.

[0022] (15) In addition, one embodiment of the present invention is a liquid crystal display device in which, in addition to the configuration of (12), (13), or (14) above, at least one of the first pixel electrode and the second pixel electrode is made of a light-shielding material. [Effects of the Invention]

[0023] According to the present invention, it is possible to provide a liquid crystal display device that can achieve high resolution while ensuring an aperture ratio. [Brief explanation of the drawing]

[0024] [Figure 1] This is a schematic diagram showing the pixel configuration in an IPS mode liquid crystal display. [Figure 2] This is a schematic diagram showing the pixel configuration in a liquid crystal display device in FFS mode. [Figure 3] This is a schematic diagram showing the pixel configuration in the liquid crystal display device of this disclosure. [Figure 4] This is a schematic plan view showing the pixel configuration in the liquid crystal display device according to Embodiment 1. [Figure 5] This figure schematically shows a cross-section of the array substrate along line AA in Figure 4. [Figure 6] This is a diagram illustrating the system configuration of a liquid crystal display device according to Embodiment 1. [Figure 7] This is a schematic plan view showing the pixel configuration of the liquid crystal display device of Example 2. [Figure 8] This is a schematic plan view showing a first pixel electrode in which a bent portion is provided at one end of the electrode. [Figure 9] This is a schematic plan view showing a first pixel electrode with bent portions provided at both ends of the electrode. [Modes for carrying out the invention]

[0025] (Summary of this disclosure) The liquid crystal display device of this disclosure achieves the same movement of liquid crystal molecules as an IPS mode liquid crystal display device without using a common electrode, thereby significantly reducing the processing accuracy issues of the pixel structure and greatly improving the aperture ratio (transmittance) and light utilization efficiency of the LCD for ultra-high-definition HMDs. Figure 3 is a schematic diagram showing the pixel configuration in the liquid crystal display device of this disclosure. As shown in the figure, the liquid crystal display device of this disclosure is provided with a second pixel electrode PE0, and a plurality of first pixel electrodes PE0 are provided within the display area. n-1 and PE n These are arranged in a row, and a common electrode may not be provided, and the first pixel electrode PE of the adjacent row n-1 and PE n The liquid crystal molecules within the display area are driven by the electric field formed between them. That is, the pixel electrode PE of the (n-1)th column n-1 The pixel electrode PE of the nth column is based on the voltage applied to it. n The design concept involves determining the voltage applied to the pixels in the nth column, thereby causing the display unit 100 to display a predetermined gradation. Specifically, in the circuit section that converts the video signal into an output signal from the source driver, for example, the maximum applied voltage to the pixel electrodes is set to A max (V) is the voltage that achieves a predetermined grayscale level in the video signal, and C is the voltage applied to the pixel of the (n-1)th column. n-1 (V), applied voltage C to the nth pixel. n When (V), C n-1 +B≦A max At that time C n =C n-1 Let +B and C n-1 +B>A max At that time C n =C n-1 The operation -B results in C n This is one of the factors that determines this. With this driving method, it becomes possible to display the same as an IPS mode liquid crystal display without a common electrode. By not providing a common electrode, high resolution can be achieved while maintaining the aperture ratio.

[0026] Hereinafter, embodiments of the liquid crystal display device described herein will be explained with reference to the drawings. The same reference numerals are used in common across different drawings for identical parts or parts having similar functions, and repeated explanations will be omitted as appropriate.

[0027] (Embodiment 1) The configuration of the liquid crystal display device of Embodiment 1 will be described using Figures 4 to 6. Figure 4 is a schematic plan view showing the pixel configuration in the liquid crystal display device according to Embodiment 1. Figure 5 is a schematic diagram showing a cross-section of the array substrate along line AA in Figure 4. Figure 6 is a diagram illustrating the system configuration of the liquid crystal display device according to Embodiment 1. In the liquid crystal display device of Embodiment 1, a plurality of pixels are arranged in a matrix of M rows and N columns (where M and N are integers of 2 or more). In this disclosure, the term "pixel" is not particularly limited as long as it corresponds to a display unit that constitutes the screen of the liquid crystal display device, and may also be called a "subpixel".

[0028] The liquid crystal display device of Embodiment 1 comprises a liquid crystal layer (not shown) containing a liquid crystal material (liquid crystal molecules). The liquid crystal material used exhibits nematic liquid crystal properties within a certain temperature range. The liquid crystal layer is sandwiched between two opposing substrates. Polarizers are placed on the opposite side of the liquid crystal layer from each of the two substrates that sandwich the liquid crystal layer. The amount of light transmitted through the liquid crystal layer is controlled by changing the orientation of the liquid crystal molecules between the polarizers. One of the two substrates that sandwich the liquid crystal layer is the array substrate 1, and the other is the opposing substrate.

[0029] The array substrate 1 has a plurality of regularly arranged nonlinear elements (element array), signal lines that supply signals to the nonlinear elements, and scan lines that drive the nonlinear elements. In this embodiment, thin-film transistors (TFTs) are regularly arranged on the first substrate 10 as nonlinear elements, a source bus line 18 is provided as a signal line that supplies voltage based on a video signal to the nonlinear elements, and a gate bus line 16 is provided as a scan line that drives the nonlinear elements. The TFT comprises three electrodes: a gate electrode which is part of the gate bus line 16, a source electrode 20 branched from the source bus line 18, and a drain electrode 22, and a semiconductor layer 12. The gate electrode (gate bus line 16) and the semiconductor layer 12 are electrically insulated by a gate insulating film 14. When the TFT is in the off state, the source electrode 20 and the drain electrode 22 are electrically isolated via the semiconductor layer 12, and when the TFT is turned on by a scan signal supplied to the gate electrode, the source electrode 20 and the drain electrode 22 are electrically connected via the semiconductor layer 12. An insulating layer consisting of a color filter layer 30 and an organic planarization film 32 is provided on the upper layer of the TFT, and a plurality (M × N) of first pixel electrodes PE and M second pixel electrodes PE0 are arranged on the insulating layer. Through holes (also called contact holes) are provided in the insulating layer, and the drain electrode 22 of the TFT is electrically connected to the first pixel electrode PE or the second pixel electrode PE0 via the through holes. The second pixel electrode PE0 may have the same structure as the first pixel electrode PE or may have a different structure.

[0030] In this disclosure, the term "first pixel electrode PE" refers to the entirety of M × N first pixel electrodes, or any first pixel electrode among M × N first pixel electrodes, and the first pixel electrode of the xth column (where x is any integer) is referred to as "first pixel electrode PE". x It is written as "".

[0031] A plurality of first pixel electrodes PE are provided in a display area (an area where pixels are arranged), corresponding to each of the plurality of pixels, arranged side by side in the first row to the M-th row in the column direction, and arranged side by side in the first column to the N-th column in the row direction. In the present disclosure, the column direction corresponds to the direction in which the source bus line 18 extends. Note that the column numbers may be assigned from one end to the other end in the row direction of the display area. For example, they may be counted in order from the left end or in order from the right end. The above "first column" may be the leftmost column or the rightmost column in the row direction. Similarly, the row numbers may be assigned from one end to the other end in the column direction of the display area.

[0032] In FIG. 4, among the plurality of first pixel electrodes PE, the first pixel electrode PE1 in the first column, the first pixel electrode PE2 in the second column, and the first pixel electrode PE in the n-th column (n is an arbitrary integer of 2 or more and n < N) n , the first pixel electrode PE in the (n - 1)-th column n-1 , the first pixel electrode PE in the (n - 2)-th column n-2 , and the first pixel electrode PE in the (n - 3)-th column n-3 are shown. In the case of a liquid crystal display device that performs color display using three-color color filters of red (R), green (G), and blue (B), for example, the pixel in which the first pixel electrode PE in the n-th column n is arranged, the pixel in which the first pixel electrode PE in the (n - 1)-th column [[ID=I7]] n-1 is arranged, and the pixel in which the first pixel electrode PE in the (n - 2)-th column n-2 is arranged may respectively correspond to the R sub-pixel, the G sub-pixel, and the B sub-pixel.

[0033] The second pixel electrode PE0 is arranged at a position adjacent to each of the M first pixel electrodes PE1 in the first column on the opposite side to the first pixel electrode PE2 in the second column in the row direction. The second pixel electrode PE0 is distinguished from the first pixel electrode PE in that a drive signal generated from a video signal is not input.

[0034] When a voltage is applied to multiple first pixel electrodes PE and second pixel electrodes PE0, the orientation of liquid crystal molecules can be changed. The application of voltage to the multiple first pixel electrodes PE and second pixel electrodes PE0 is controlled by a control unit, which will be described later.

[0035] From the viewpoint of increasing pixel resolution, the first pixel electrode PE preferably has a linear shape without branched portions. A linear shape means that the ratio of length to width is 3 or more. The first pixel electrode PE shown in Figure 4 is a single linear shape except for the through-hole portion. The first pixel electrode PE having a linear shape without branched portions may have a wider portion due to the through-hole portion, and its tip may be bent.

[0036] The angle between the first direction in which the main portion of the linear-shaped first pixel electrode PE extends, including the central part, and the direction in which the source bus line 18 extends is preferably 15° or less, and more preferably 5° or less. This allows for a larger pixel aperture ratio and higher transmittance (because the molecular tilt approaches 90 degrees when an electric field is applied to the liquid crystal), as well as suppressing light leakage during black display (because interference between the incident polarized light and the edge of the first pixel electrode PE can be suppressed), and also increases the display contrast.

[0037] The linear first pixel electrode PE may have a main portion extending in a first direction, including its central part, and a bent portion extending in a second direction, connected to at least one end of the main portion in the first direction. Preferably, the angle between the second direction and the direction in which the source bus line extends is greater than the angle between the first direction and the direction in which the source bus line extends. At the ends of the electrode, the electric field lines are disturbed, making it difficult to determine the direction of movement of liquid crystal molecules when an electric field is applied to the liquid crystal, which may result in a slow response speed. However, by adopting such a structure (which has the effect of speeding up the response in that part), the decrease in response speed can be suppressed. Figure 8 is a schematic plan view showing a first pixel electrode with a bent portion provided at one end of the electrode. Figure 9 is a schematic plan view showing a first pixel electrode with bent portions provided at both ends of the electrode. The first pixel electrode PE with the shape shown in Figure 8 or Figure 9 may be applied instead of the first pixel electrode PE with the shape shown in Figure 4.

[0038] From the viewpoint of increasing the aperture ratio, it is preferable that the area of ​​the first pixel electrode PE overlapping with the source bus line 18 is large. For example, 50% or more of the area of ​​the first pixel electrode PE (or the area of ​​the linear main part) overlaps with the source bus line 18.

[0039] As shown in Figure 4, the first pixel electrode PE has a linear main portion which is superimposed on the source bus line 18 and a second portion which is not superimposed on the source bus line 18. The second portion includes a portion located on one side of the source bus line 18 in the row direction (a direction perpendicular to the direction in which the source bus line 18 extends) and a portion located on the other side of the source bus line 18 in the row direction.

[0040] From the viewpoint of increasing the aperture ratio and processing accuracy, the distance DE between two adjacent first pixel electrodes PE is preferably 70% or more of the distance DL between two adjacent source bus lines 18, and more preferably greater than the distance DL between two adjacent source bus lines 18 (100% or more).

[0041] The first pixel electrode PE and the second pixel electrode PE0 may be made of a transparent conductive film. When the first pixel electrode PE and the second pixel electrode PE0 are made of a transparent conductive film, the only light-shielding portion separating each pixel arranged in the row direction in Figure 4 is the source bus line 18, making it easier to increase the aperture ratio.

[0042] At least one of the first pixel electrode PE and the second pixel electrode PE0 may be made of a light-shielding material such as a metal film. This prevents the occurrence of color mixing, where light transmitted through adjacent pixels mixes when the array substrate 1 is viewed from an oblique direction, by at least one of the first pixel electrode PE and the second pixel electrode PE0, thereby effectively preventing color mixing of the display light in the liquid crystal display device.

[0043] In a plan view, a source bus line 18 connected to the TFT is positioned between the source electrode 20 and the drain electrode 22 of the TFT.

[0044] The opposing substrate has a black matrix BM that extends in the row direction so as to face the gate bus line 16 of the array substrate 1 in a plan view. The black matrix BM in this embodiment is not a grid-like black matrix and does not have portions that extend in the column direction.

[0045] The liquid crystal display device of Embodiment 1 includes a control unit. The control unit includes a drive circuit and a source driver 230. After the video signal is converted into a drive signal by the control unit, it is supplied to a plurality of first pixel electrodes PE. Specifically, a video signal input from outside the liquid crystal display device via wired or wireless communication means is input to a drive circuit provided on a circuit board. Signal processing is performed in the drive circuit using an FPGA (Field Programmable Gate Array) to generate a drive signal suitable for the drive method of this disclosure in which no common electrode is provided. The drive circuit and the source driver 230 are electrically connected via a connector 210 and a flexible printed circuit board 220. The source driver 230 is located in the bezel area of ​​the liquid crystal display device and is electrically connected to the drive circuit and the signal lines (source bus lines 18) of the array board 1. The drive signal generated by the drive circuit is output from the source driver 230 and supplied to the first pixel electrodes PE via the source bus lines 18 of the array board 1. As a result, a voltage based on the video signal is applied to the first pixel electrodes PE.

[0046] Next, the driving method of the liquid crystal display device of Embodiment 1 will be described. In this embodiment, M second pixel electrodes PE0 are electrically connected to signal lines to which a predetermined voltage can be applied, and a predetermined voltage is applied when driving liquid crystal molecules within the display area. In addition, multiple first pixel electrodes PE are to which a drive signal (voltage based on the video signal) generated from the video signal is applied. The drive signal is adjusted so that each pixel displays a desired grayscale based on the video signal.

[0047] The control unit applies a predetermined voltage to M second pixel electrodes PE0 and a voltage based on the video signal to the first pixel electrode PE1 of the m-row, 1-column arrangement in order to control the display of the pixels in the m-row, 1-column arrangement. The electric field formed between the first pixel electrode PE1 of the m-row, 1-column arrangement and the second pixel electrode PE0 adjacent to it in the row direction drives the liquid crystal molecules belonging to the pixels in the m-row, 1-column arrangement, thereby displaying the desired grayscale. The control unit controls the display of the first pixel electrode PE of the m row and n column (where n is any integer between 2 and N) in order to control the display of the m row and n column. n and the first pixel electrode PE in row m (n-1) column n-1 A voltage based on the video signal is applied to it. The first pixel electrode PE in the m row and n column. n and the first pixel electrode PE in row m (n-1) column n-1 The electric field formed between the two drives the liquid crystal molecules belonging to the m x n pixels, displaying the desired grayscale. With this driving method, the liquid crystal layer can be driven in a horizontal alignment mode without a common electrode, thus enabling high resolution while maintaining the aperture ratio.

[0048] The second pixel electrode PE0 is used to apply a reference voltage (a predetermined voltage) for determining the voltage that drives the m-row, 1-column pixels. The structure of the second pixel electrode PE0 is not particularly limited as long as it is positioned adjacent to the first pixel electrode PE1 in the m-row, 1-column arrangement and to which the predetermined voltage is applied; it may have exactly the same structure as the first pixel electrodes PE in the first column and beyond. The voltage applied to the second pixel electrode PE0 is not a voltage determined from the video signal, but can be set to any voltage within the range that can be output from the source driver 230. The predetermined voltage applied to the second pixel electrode PE0 is a preset constant voltage, for example, between -6V and 6V. The predetermined voltage applied to the second pixel electrode PE0 may always be constant, or the constant value may be changed at predetermined intervals. For example, the constant value may be changed between the positive and negative fields in one frame. The second pixel electrode PE0 may have the same configuration as the first pixel electrode PE. The signal line to which the second pixel electrode PE0 is connected is not particularly limited as long as it is possible to apply a predetermined voltage, and a signal line (source bus line 18) may be used in the same way as the first pixel electrode PE. In this case, the nonlinear element and the second pixel electrode PE0 may be electrically connected via a through-hole.

[0049] The second pixel electrode PE0 described above has a shape similar to that of the first pixel electrode PE, preferably substantially identical in shape to that of the first pixel electrode PE, and more preferably identical in shape. The closer the shape of the second pixel electrode PE0 is to the shape of the first pixel electrode PE of the first row, the easier it is to match the electric field pattern formed between the second pixel electrode PE0 and the first pixel electrode PE of the first row with the electric field pattern formed between the first pixel electrodes PE of adjacent rows.

[0050] The control unit may perform the following processing: determine the voltage to be applied to the first pixel electrode PE in the m-row, 1-column position based on the gradation displayed in the m-row, 1-column pixel, using the predetermined voltage as a reference; and determine the voltage to be applied to the first pixel electrode PE in the m-row, n-column position based on the voltage applied to the first pixel electrode PE in the m-row, n-column position based on the gradation displayed in the m-row, n-column pixel. This allows the liquid crystal layer to be driven in horizontal alignment mode while utilizing the second pixel electrode PE0. The gradation displayed in the m-row, 1-column pixel and the gradation displayed in the m-row, n-column pixel are included as data in the video signal.

[0051] The maximum applied voltage to multiple first pixel electrodes PE is set to A. max (V) The minimum applied voltage to multiple first pixel electrodes is A min (V), the voltage that realizes the grayscale displayed in the m x n pixels is B. n (V), the voltage applied to the first pixel electrode PE in row m (n-1) is C n-1 (V), the voltage applied to the first pixel electrode PE in the m row and n column is C n When (V) is defined, the control unit is C n (V) may be determined by either formula (1) or (2) below, or by either formula (3) or (4) below. Formula (1):C n-1 +B n ≤A max When C n =C n-1 +B n Formula (2):C n-1 +B n >A max When C n =Cn-1 -B n Formula (3): C n-1 -B n ≥A min When, C n = C n-1 -B n Formula (4): C n-1 -B n < A min When, C n = C n-1 +B n According to the above processing, it is possible to realize the driving method of the present disclosure while preventing the maximum applied voltage A max from becoming too large and the minimum applied voltage A min from becoming too small. The maximum applied voltage A max is set, for example, to +4V or more and +8V or less, and the minimum applied voltage A min is set, for example, to -8V or more and -4V or less. The voltage B (B1, B n ) is the voltage applied to the liquid crystal layer so that the transmittance of the liquid crystal layer corresponding to the gradation displayed on the pixel can be obtained when based on 0V. In the driving method of the present disclosure in which no common electrode is provided, in the pixels of m rows and n columns, the voltage applied to the liquid crystal layer is the potential difference between the voltage C n applied to the first pixel electrode PE n in the nth column and the voltage C n-1 applied to the first pixel electrode PE n-1 in the previous column. Therefore, the control unit determines C n (V) according to any one of the above formulas (1) to (4).

[0052] When defining the predetermined positive voltage applied to the second pixel electrode PE0 as D1 (V), the predetermined negative voltage applied to the second pixel electrode PE0 as D2 (V), the voltage realizing the gradation displayed on the pixel of m rows and 1 column as B1 (V), and the voltage applied to the first pixel electrode in m rows and 1 column as C1 (V), the above control unit may perform the process of determining C1 (V) according to any one of the following formulas (5) and (6) or any one of the following formulas (7) and (8). Formula (5): D1 + B1 ≤ A maxIn that case, C1 = D1 + B1 Formula (6): D1+B1>A max In that case, C1 = D1 - B1 Formula (7): D2-B1≧A min In this case, C1 = D2 - B1 Formula (8): D2-B1 min In that case, C1 = D2 + B1 According to the above process, the maximum applied voltage A max The value may become too large or the minimum applied voltage A min This allows for the realization of the driving mechanism of this disclosure while preventing the size from becoming too small.

[0053] The control unit may reverse the polarity of the predetermined voltage between the positive and negative fields within a frame to AC drive the M second pixel electrodes PE0 and the m-row, 1-column first pixel electrodes. This allows a substantially AC electric field to be applied to the liquid crystal layer while utilizing the second pixel electrodes PE0 in the driving method of this disclosure. The AC driving is performed, for example, such that a positive field in which a positive voltage is applied to the second pixel electrodes PE0 and a negative field in which a negative voltage is applied to the second pixel electrodes PE0 are included within one frame that constitutes one screen.

[0054] The control unit described above controls the positive field in one frame. n (V) is determined by either equation (1) or (2) above, and C in the negative field within one frame. n (V) may be determined by either equation (3) or (4) above to drive the first pixel electrode in the m row and n column with AC power. For example, the maximum applied voltage A max When is +a(V), the minimum applied voltage A min This can also be -a(V). This makes it possible to make the voltage applied to the liquid crystal layer symmetrical in the positive and negative fields.

[0055] ​The liquid crystal display device of Embodiment 1 may superimpose a constant DC component onto the voltage applied to each of the multiple first pixel electrodes PE. This makes it possible to compensate for voltage fluctuations due to parasitic capacitance (Cgd) when the gate voltage switches from ON to OFF in the pixel TFT, thereby suppressing flicker during display. If the voltage fluctuation is ΔVp, the ON / OFF difference of the gate voltage is Vg, the capacitance of the pixel liquid crystal is Clc, and the pixel incident capacitance is Cs, then ΔVp = Vg × Cgd / (Cgd + Clc + Cs). To compensate for the voltage fluctuation, it is preferable to apply a DC component corresponding to ΔVp to the liquid crystal. In this driving method, since no common electrode is provided, a DC component is applied to the first pixel electrode PE. Even if the above DC component is not applied, flicker becomes less visible when the pixel driving frequency is high (for example, 120 Hz), but the asymmetry of the applied voltage remains, so it is preferable to superimpose a DC component. In typical liquid crystal displays, N-type semiconductors are used for the pixel TFTs, so voltage fluctuations due to parasitic capacitance are on the negative side. In this case, the DC component mentioned above is superimposed on the positive side. The voltage of the DC component is usually around +0.1 to +0.2V.

[0056] One aspect of the liquid crystal display device of this disclosure is that a predetermined voltage is applied to the second pixel electrode, and another aspect of the liquid crystal display device of this disclosure is that the first pixel electrode has a linear shape without branched portions. In other words, the liquid crystal display device of this disclosure may not have a predetermined voltage applied to the second pixel electrode, as long as the first pixel electrode has a linear shape without branched portions.

[0057] The following are examples of the liquid crystal display device of this disclosure, but the present invention is not limited to these examples.

[0058] (Example 1) In Example 1, the liquid crystal display device of Embodiment 1 was actually fabricated using the following procedure. The liquid crystal display device fabricated in Example 1 will be described in detail with reference to Figures 4 to 6. The liquid crystal display device fabricated in Example 1 is assumed to be a TFT-LCD for HMDs with a resolution of approximately 1700 ppi, with the size of each pixel set to 15 μm square and the size of each subpixel of each color set to 5 × 15 μm.

[0059] (1) Fabrication of array substrates A TFT or the like was formed on the first substrate 10, comprising a gate electrode (gate bus line 16), a gate insulating film 14, and a semiconductor layer 12 made of IGZO, an oxide semiconductor. The width of the source bus line 18, which has a large effect on the aperture ratio, was set to 1.5 μm. Next, a color filter layer 30 of red, green, and blue was formed using a colored organic resist, and an organic material was applied on top of it to form an organic planarization film (overcoat layer) 32. A flat surface was obtained by the organic planarization film 32. Next, after creating through-hole openings in the color filter layer 30 and the organic planarization film 32, a transparent conductive film was laminated. This formed a first pixel electrode PE connected to the drain electrode 22 of the TFT via a through-hole. In plan view, the first pixel electrode PE had a linear shape without branched portions. Furthermore, an alignment film was applied and oriented in a direction that forms a 5° angle with respect to the extension direction of the linear first pixel electrode PE (indicated by arrow D in Figure 4). With these steps completed, the array substrate 1 was finished.

[0060] (2) Fabrication of liquid crystal display devices On the second substrate, a black matrix was formed only in the row direction (parallel to the gate bus line 16), and then an alignment film was formed. After that, an alignment process was performed so that the alignment direction was aligned with that of the alignment film on the array substrate 1 side. With the above steps, the opposing substrate was completed. Next, the array substrate 1 and the opposing substrate were bonded together with a liquid crystal layer in between, the polarizing plate, driver, and drive circuit were connected, and the liquid crystal display device was fabricated by combining it with the backlight system.

[0061] (3) Driving the liquid crystal display In the drive circuit, an FPGA was used for signal processing to convert the video signal into a drive signal. In this signal processing, the maximum applied voltage to the source driver 230 was set to 5V and the minimum applied voltage to -5V. Then, for a pixel with m rows and 1 column (where m is any integer greater than or equal to 1), D1(V) is a predetermined positive voltage applied to the second pixel electrode PE0 in the positive field during one frame, D2(V) is a predetermined negative voltage applied to the second pixel electrode PE0 in the negative field during one frame, B1(V) is the voltage that realizes the gradation displayed on the m row and 1 column pixel, and C1(V) is the voltage applied to the first pixel electrode of the m row and 1 column. In the positive field, the calculation is performed as follows: C1=D1+B1 when D1+B1≦5V, and C1=D1-B1 when D1+B1>5V. In the negative field, the calculation is performed as follows: C1=D2-B1 when D2-B1≧-5V, and C1=D2+B1 when D2-B1<-5V to determine C1(V). Furthermore, for an m x n pixel (where n is any integer greater than or equal to 2), the voltage used to achieve the gradation displayed in the m x n pixel is B. n Let (V) be the first pixel electrode PE in row m (n-1). n-1 The voltage applied to C n-1 Let (V) be the first pixel electrode PE in the m row and n column. n The voltage applied to C n When (V) is the case, in the positive field, C n-1 +B n When the voltage is ≤5V, C n =C n-1 +B n , C n-1 +B n >When it is 5V C n =C n-1 -B n This operation is performed, and in the negative field, C n-1 -B n When C is ≥ -5V n =C n-1 -B n , C n-1 -B n When the voltage is <-5V, C n =C n-1 +B n Perform the operation C n(V) was decided.

[0062] (4) Characterization of liquid crystal display devices The liquid crystal display device of Example 1 was able to appropriately display each grayscale level and obtain a transmittance characteristic that was approximately 1.6 times that of the FFS-LCD simulation results with the same resolution.

[0063] (Example 2) Figure 7 is a schematic plan view showing the pixel configuration of the liquid crystal display device of Example 2. In Example 1, there was an angle between the first pixel electrode PE and the source bus line 18, but in Example 2, the first pixel electrode PE is provided parallel to the source bus line 18. Regarding Example 2, the points that are common to Example 1 will not be explained.

[0064] As shown in Figure 7, the first pixel electrode PE has a linear main portion which is superimposed on the source bus line 18 and a second portion which is not superimposed on the source bus line 18. The second portion is positioned on one side of the source bus line 18 in the row direction (the direction perpendicular to the direction in which the source bus line 18 extends).

[0065] Furthermore, both the array substrate and the opposing substrate were oriented in a direction that is at an angle to the first pixel electrode PE (indicated by arrow D in Figure 7). The orientation direction of the array substrate and the opposing substrate was made identical when viewed from the front after bonding. Ideally, the first pixel electrode PE should be formed narrower than the source bus line 18, but due to processing accuracy issues, the first pixel electrode PE was formed wider. Since the first pixel electrode PE is transparent, the aperture width of the pixel is equal to the spacing of the source bus line 18. According to Example 2, the transmittance could be improved by 5-10% compared to Example 1.

[0066] Furthermore, it is preferable to set the absorption axis of the polarizing plate to match the orientation direction of the liquid crystal. If the polarized light incident on the liquid crystal panel is at an angle that is not perpendicular or parallel to the orientation direction of the liquid crystal, slight depolarization due to light interference and scattering may occur when the polarized light hits the edge of a metal pattern such as the source bus line 18, causing light leakage and potentially reducing the display contrast.

[0067] (modified version) In Examples 1 and 2, an FPGA was used as the driving circuit, but it is also possible to implement it as an IC.

[0068] The first pixel electrode PE may be formed from a transparent conductive film such as ITO or IZO, or from a light-shielding material such as a metal film to prevent color mixing from oblique viewing.

[0069] The color filter layer 30 may be formed on the opposing substrate. If the bonding accuracy between the array substrate 1 and the opposing substrate is not sufficiently high, the aperture ratio may not be secured.

[0070] The signal processing in the control unit (drive circuit) can be adjusted to match the drive method, and may take the following forms, for example.

[0071] [1] The potential of the voltage applied to the second pixel electrode PE0 may be 0, but the polarity may be reversed for each driving field. For example, it may be -5V for odd fields and +5V for even fields.

[0072] [2] In order to make the electric field applied to the liquid crystal layer an AC component, for example, one of equations (3) and (4) and one of equations (7) and (8) above may be used for odd fields, and one of equations (1) and (2) and one of equations (5) and (6) above may be used for even fields, thereby inverting the sign of the signal processing calculation formula for each field.

[0073] [3] Because a DC component may be superimposed on the signal applied to the liquid crystal layer due to the parasitic capacitance of the TFT, a constant bias (DC component) may be applied to the entire drive signal applied to the source electrode 20.

[0074] [4] In order to speed up the response speed of liquid crystal molecules, a driving method (so-called overshoot driving) may be used in which a voltage greater than or less than the voltage required to achieve the grayscale displayed on the pixel is applied for a short period of time. Overshoot driving can be realized by a combination of a lookup table and calculations. [Explanation of symbols]

[0075] 1: Array substrate 10: First circuit board 12: Semiconductor layer 14: Gate Insulator 16: Gate bus line (gate gate) 18: Source bus line 20: Source electrode 22: Drain electrode 30: Color filter layer 32:Organic planarization film 100:Display section 210: Connector 220: Flexible wiring board 230: Source Driver 300, 400: Display section 310, 410: Pixel electrodes 320, 420: Common electrode PE: First pixel electrode PE0: Second pixel electrode PE1: First pixel electrode of the first row of pixels. PE2: First pixel electrode of the second row of pixels PE n : The first pixel electrode of the nth column pixel PE n-1 : The first pixel electrode of the pixel in the (n-1)th column. PE n-2 : The first pixel electrode of the pixel in the (n-2)th column. PE n-3 : The first pixel electrode of the pixel in the (n-3)th column.

Claims

1. Multiple pixels arranged in a matrix of M rows and N columns (where M and N are integers greater than or equal to 2), An array substrate having a plurality of first pixel electrodes provided corresponding to each of the plurality of pixels, and M second pixel electrodes positioned adjacent to each of the M first pixel electrodes in the first column of the plurality of first pixel electrodes on the opposite side from the first pixel electrodes in the second column in the row direction, A liquid crystal layer containing liquid crystal molecules, The system includes a control unit that applies a predetermined voltage to the M second pixel electrodes and applies a voltage based on a video signal to the plurality of first pixel electrodes, so that for a pixel in m rows and 1 column (where m is any integer from 1 to M), the liquid crystal molecules belonging to that pixel are driven by an electric field formed between the first pixel electrode in m rows and 1 column of the plurality of first pixel electrodes and the second pixel electrode adjacent to the first pixel electrode in the row direction of the M second pixel electrodes, and so that for a pixel in m rows and n columns (where n is any integer from 2 to N), the liquid crystal molecules belonging to that pixel are driven by an electric field formed between the first pixel electrode in m rows and n column and the first pixel electrode in m rows and (n-1) column of the plurality of first pixel electrodes. LCD display device.

2. The liquid crystal display device according to claim 1, wherein the control unit determines a voltage to be applied to the first pixel electrode of the m row and 1 column based on the grayscale displayed in the m row and 1 column, using the predetermined voltage as a reference, and determines a voltage to be applied to the first pixel electrode of the m row and n column based on the voltage applied to the first pixel electrode of the m row and (n-1) column, using the voltage applied to the first pixel electrode of the m row and n column as a reference.

3. The maximum applied voltage to the plurality of first pixel electrodes is set to A. ｍａｘ (V) The minimum applied voltage to the plurality of first pixel electrodes is A ｍｉｎ (V) The voltage that realizes the gradation to be displayed in the m row and n column pixels is B ｎ (V) The voltage applied to the first pixel electrode of the m row (n-1) column is C ｎ－１ (V) The voltage applied to the first pixel electrode of the m row and n column is C ｎ When we define (V), The control unit is C ｎ The liquid crystal display device according to claim 2, wherein (V) is determined by either formula (1) or (2) below, or by either formula (3) or (4) below. Formula (1): C ｎ－１ + B ｎ ≤ A ｍａｘ When, C ｎ = C ｎ－１ + B ｎ Formula (2):C ｎ－１ +B ｎ > A ｍａｘ At that time, C ｎ = C ｎ－１ -B ｎ Formula (3):C ｎ－１ -B ｎ ≧A ｍｉｎ At that time, C ｎ = C ｎ－１ -B ｎ Formula (4):C ｎ－１ -B ｎ <A ｍｉｎ At that time, C ｎ = C ｎ－１ +B ｎ

4. The liquid crystal display device according to claim 2, wherein the control unit reverses the polarity of the predetermined voltage between the positive field and the negative field in one frame to AC drive the M second pixel electrodes and the m row and 1 column first pixel electrodes.

5. The control unit controls the positive field in one frame. ｎ (V) is determined by either formula (1) or (2) above, and C in the negative field within one frame ｎ The liquid crystal display device according to claim 3, wherein (V) is determined by either formula (3) or (4) and the first pixel electrode of the m row and n columns is driven by alternating current.

6. The liquid crystal display device according to any one of claims 1 to 5, wherein a constant DC component is superimposed on the voltage applied to each of the plurality of first pixel electrodes.

7. The liquid crystal display device according to any one of claims 1 to 5, wherein the second pixel electrode has substantially the same shape as the first pixel electrode.

8. The liquid crystal display device according to any one of claims 1 to 5, wherein the first pixel electrode has a linear shape without branched portions.

9. The array substrate further has a source bus line to which a voltage based on the video signal is supplied, The angle between the first direction in which the main portion of the first pixel electrode, including the central part, extends and the direction in which the source bus line extends is 15° or less. The liquid crystal display device according to claim 8.

10. The earlier array substrate further has a source bus line to which a voltage based on the video signal is supplied, The first pixel electrode has a main portion extending in a first direction including its central part, and a bent portion extending in a second direction, connected to at least one end of the main portion in the first direction. The liquid crystal display device according to claim 8, wherein the angle between the second direction and the direction in which the source bus line extends is greater than the angle between the first direction and the direction in which the source bus line extends.

11. The liquid crystal display device according to any one of claims 1 to 5, wherein at least one of the first pixel electrode and the second pixel electrode is made of a light-shielding material.

12. Multiple pixels arranged in a matrix of M rows and N columns (where M and N are integers greater than or equal to 2), An array substrate having a plurality of first pixel electrodes provided corresponding to each of the plurality of pixels, and M second pixel electrodes positioned adjacent to each of the M first pixel electrodes in the first column of the plurality of first pixel electrodes on the opposite side from the first pixel electrodes in the second column in the row direction, A liquid crystal layer containing liquid crystal molecules, The system includes a control unit that applies a voltage to the M second pixel electrodes and applies a voltage based on a video signal to the plurality of first pixel electrodes, such that for a pixel in m rows and 1 column (where m is any integer between 1 and M), the liquid crystal molecules belonging to that pixel are driven by an electric field formed between the first pixel electrode in m rows and 1 column of the plurality of first pixel electrodes and the second pixel electrode adjacent to the first pixel electrode in the row direction among the M second pixel electrodes, and for a pixel in m rows and n columns (where n is any integer between 2 and N), the liquid crystal molecules belonging to that pixel are driven by an electric field formed between the first pixel electrode in m rows and n columns and the first pixel electrode in m rows and (n-1) columns among the plurality of first pixel electrodes, The first pixel electrode has a linear shape without branched portions. LCD display device.

13. The array substrate further has a source bus line to which a voltage based on the video signal is supplied, The angle between the first direction in which the main portion of the first pixel electrode, including the central part, extends and the direction in which the source bus line extends is 15° or less. The liquid crystal display device according to claim 12.

14. The array substrate further has a source bus line to which a voltage based on the video signal is supplied, The first pixel electrode has a main portion extending in a first direction including its central part, and a bent portion extending in a second direction, connected to at least one end of the main portion in the first direction. The liquid crystal display device according to claim 12, wherein the angle between the second direction and the direction in which the source bus line extends is greater than the angle between the first direction and the direction in which the source bus line extends.

15. The liquid crystal display device according to any one of claims 12 to 14, wherein at least one of the first pixel electrode and the second pixel electrode is made of a light-shielding material.

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