JP2010002596A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a phenomenon of generating flickers by a flexoelectric effect when an IPS (in-plane switching) liquid crystal display is driven in a frame reversal mode. <P>SOLUTION: Four interdigital electrodes 1101 are present in one region of a pixel electrode 110, while three interdigital electrodes 1101 are present in the other region. A common electrode formed as a flat solid electrode is formed below the pixel electrode 110 interposing an insulating film. When the potential of the pixel electrode 110 is higher than that of the common electrode by a flexoelectric effect, dark lines appear on the interdigital electrodes 1101; and when the potential of the pixel electrode 110 is lower than that of the common electrode, dark lines appear in slit portions 112. By employing the feature of the pixel electrode shown in the figure, the number of dark lines is the same regardless to the relative potential between the pixel electrode 110 and the common electrode, which suppresses flickers. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a display device, and more particularly, to a liquid crystal display device that is a horizontal electric field method with excellent viewing angle characteristics, has high backlight utilization efficiency, and has less flicker.

  In a liquid crystal display device, there are a TFT substrate in which pixel electrodes and thin film transistors (TFTs) are formed in a matrix, and a counter substrate in which color filters are formed at locations corresponding to the pixel electrodes of the TFT substrate, facing the TFT substrate. The liquid crystal is sandwiched between the TFT substrate and the counter substrate. An image is formed by controlling the light transmittance of the liquid crystal molecules for each pixel.

  A viewing angle characteristic is a problem in a liquid crystal display device. The viewing angle characteristic is a phenomenon in which luminance changes or chromaticity changes when the screen is viewed from the front and when viewed from an oblique direction. The viewing angle characteristic is excellent in an IPS (In Plane Switching) system in which liquid crystal molecules are operated by a horizontal electric field.

  On the other hand, the liquid crystal has a phenomenon called flexoelectric effect. Conventionally, it has been considered that the alignment state of liquid crystal molecules does not depend on whether the applied voltage is positive or negative, but strictly speaking, due to the flexoelectric effect, the alignment is different between positive and negative. The operation of the liquid crystal display device is set so that AC driving is performed and no DC component is generated in order to avoid electrolysis of the liquid crystal.

  However, when there is a flexoelectric effect, even if the applied voltage to the liquid crystal molecules is a complete alternating current, the brightness varies depending on whether the voltage applied to the pixel voltage is positive or negative. As a driving method of the liquid crystal display device, for example, there is a driving method called frame inversion. In this case, the polarity of the voltage applied to the pixel electrode is inverted every frame. As a result, even if images having the same brightness are displayed, the brightness differs for each frame due to the flexoelectric effect. This appears to the human eye as flickering and impairs the image quality.

  In “Patent Document 1”, a stripe-shaped pixel electrode and a stripe-shaped common electrode are arranged in parallel, one of the electrodes is a transparent electrode, and the other of the electrodes is a light-shielding electrode Measures against flexoelectric effects are described. That is, in the electrode configuration as in “Patent Document 1”, a portion where the transparent electrode is relatively negative with respect to the light-shielding electrode is brighter than a portion where the transparent potential is relatively positive.

  For each frame, pixels are divided in order to prevent light and darkness and flickering. On the one hand, the transparent electrode has a negative potential with respect to the light-shielding electrode. A configuration is described in which fluctuations in brightness are canceled in a pixel so that the electrode has a positive potential with respect to a light-shielding electrode.

JP 2002-202736 A

  The flexoelectric effect varies depending on the pixel structure. Various types of IPS liquid crystal display devices have been developed, but the most widely used method as a configuration capable of increasing the brightness of the screen is to form a common electrode in a flat plane, This is a system in which comb-like pixel electrodes are arranged with an insulating film interposed therebetween. A reference voltage is applied to the common electrode, a video signal is applied to the pixel electrode, and liquid crystal molecules are rotated by a potential difference between the pixel electrode and the video signal to control light transmittance.

  In this IPS method, both the pixel electrode and the common electrode are formed of a transparent conductive film. In this case, the flexoelectric effect is caused by a dark line on the comb electrode due to a relative potential between the common electrode and the pixel electrode, or a dark line is generated in the slit portion between the comb electrode and the comb electrode. It appears as a phenomenon.

  An object of the present invention is to prevent flicker due to a flexoelectric effect in an IPS liquid crystal display device having such a structure.

  The present invention overcomes the above problems, and specific means are as follows.

  (1) Pixels in a region surrounded by scanning lines extending in the first direction and arranged in the second direction and video signal lines extending in the second direction and arranged in the first direction The pixel includes a first electrode formed in a flat plane, an interlayer insulating film formed on the first electrode, and a second electrode formed on the interlayer insulating film. The second electrode has a first region and a second region, the first region has a first number of comb electrodes, and the second region has a second number. A liquid crystal display device, wherein the first number is different from the second number.

  (2) The liquid crystal display device according to (1), wherein in the second electrode, a difference between the first number and the second number is 1.

  (3) In the second electrode, the length and width of the comb electrode in the first region, and the interval between the comb electrodes are the length and width of the comb electrode in the second region. The liquid crystal display device according to (1), wherein the intervals between the comb electrodes are equal to each other.

  (4) The liquid crystal display device according to (1), wherein the first electrode is a common electrode, and the second electrode is a pixel electrode.

  (5) Pixels in a region surrounded by scanning lines extending in the first direction and arranged in the second direction and video signal lines extending in the second direction and arranged in the first direction The pixel includes a first electrode formed in a flat plane, a first interlayer insulating film formed on the first electrode, and a second electrode formed on the first interlayer insulating film. A third electrode having a comb-shaped electrode formed on the second interlayer insulating film and the second interlayer insulating film formed on the second interlayer insulating film, and the second electrode The electrode has a first region in which a comb electrode is formed and a second region in which a flat solid electrode is formed. The region of the second electrode in which the comb electrode is formed is the first region. The region where the flat electrode of the second electrode is formed overlaps with the third electrode, and the first electrode and the second electrode are the same The liquid crystal display device which is a position.

  (6) The liquid crystal display according to (5), wherein the number of the comb electrodes formed on the second electrode is equal to the number of the comb electrodes formed on the third electrode. apparatus.

  (7) The length and width of the comb electrode formed on the second electrode, and the interval between the comb electrodes are the length and width of the comb electrode formed on the third electrode, and The liquid crystal display device according to (5), wherein the intervals between the comb electrodes are equal to each other.

  (8) The liquid crystal display device according to (5), wherein the second electrode is a pixel electrode, and the first electrode and the third electrode are common electrodes.

  According to the present invention, in an IPS liquid crystal display device composed of a first electrode formed of a flat solid and a second electrode having a comb electrode, the brightness of each frame is increased by a flexoelectric effect. It is possible to prevent a phenomenon in which flicker occurs due to fluctuation.

  Hereinafter, the contents of the present invention will be described in detail according to examples.

  FIG. 1 is a cross-sectional view of an IPS liquid crystal display device to which the present invention is applied. In FIG. 1, a gate electrode 101 is formed on a TFT substrate 100 made of glass. The gate electrode 101 is formed in the same layer as the scanning line 500. The gate electrode 101 has a MoCr alloy laminated on an AlNd alloy.

  A gate insulating film 102 is formed of SiN so as to cover the gate electrode 101. A semiconductor layer 103 is formed of an a-Si film on the gate insulating film 102 at a position facing the gate electrode 101. The a-Si film is formed by plasma CVD. The a-Si film forms the channel portion of the TFT, and the source electrode 104 and the drain electrode 105 are formed on the a-Si film with the channel portion interposed therebetween. Note that an n + Si layer (not shown) is formed between the a-Si film and the source electrode 104 or the drain electrode 105. This is to make an ohmic contact between the semiconductor layer 103 and the source electrode 104 or the drain electrode 105.

  The source electrode 104 is also used as the video signal line 600, and the drain electrode 105 is connected to the pixel electrode 110. The source electrode 104 and the drain electrode 105 are simultaneously formed in the same layer. In this embodiment, the source electrode 104 or the drain electrode 105 is made of a MoCr alloy. In order to reduce the electrical resistance of the source electrode 104 or the drain electrode 105, for example, an electrode structure in which an AlNd alloy is sandwiched between MoCr alloys is used.

  An inorganic passivation film 106 is formed of SiN so as to cover the TFT. The inorganic passivation film 106 protects the TFT, particularly the channel portion, from impurities. An organic passivation film 107 is formed on the inorganic passivation film 106. The organic passivation film 107 has a role of flattening the surface at the same time as protecting the TFT, and thus is formed thick. The thickness is 1 μm to 4 μm.

  A photosensitive acrylic resin, silicon resin, polyimide resin, or the like is used for the organic passivation film 107. In the organic passivation film 107, it is necessary to form a through hole 111 at a portion where the pixel electrode 110 and the drain electrode 105 are connected. However, since the organic passivation film 107 is photosensitive, the organic passivation film 107 is not used without using a photoresist. The through hole 111 can be formed by exposing and developing itself.

  A common electrode 108 is formed on the organic passivation film 107. The common electrode 108 is formed by sputtering ITO (Indium Tin Oxide), which is a transparent conductive film, over the entire display region. That is, the common electrode 108 is formed in a planar shape. After the common electrode 108 is formed on the entire surface by sputtering, the common electrode 108 is removed by etching only in the through hole 111 portion for conducting the pixel electrode 110 and the drain electrode 105.

  A first interlayer insulating film 109 is formed of SiN so as to cover the common electrode 108. After the first interlayer insulating film 109 is formed, a through hole 111 is formed by etching. The through hole 111 is formed by etching the inorganic passivation film 106 using the first interlayer insulating film 109 as a resist. Thereafter, an ITO film that covers the first interlayer insulating film 109 and the through hole 111 and becomes the pixel electrode 110 is formed by sputtering. The pixel electrode 110 is formed by patterning the sputtered ITO. ITO serving as the pixel electrode 110 is also deposited on the through hole 111. In the through hole 111, the drain electrode 105 extending from the TFT and the pixel electrode 110 become conductive, and a video signal is supplied to the pixel electrode 110.

  The pixel electrode 110 is a comb-like electrode. A slit 112 is formed between the comb-shaped electrode and the comb-shaped electrode. A reference voltage is applied to the common electrode 108, and a voltage based on a video signal is applied to the pixel electrode 110. When a voltage is applied to the pixel electrode 110, as shown in FIG. 1, the lines of electric force are generated, and the liquid crystal molecules 301 are rotated in the direction of the lines of electric force to control the transmission of light from the backlight 700. Since transmission from the backlight 700 is controlled for each pixel, an image is formed. Note that an alignment film 113 for aligning the liquid crystal molecules 301 is formed on the pixel electrode 110.

  In the example of FIG. 1, the common electrode 108 formed in a planar shape is disposed on the organic passivation film 107, and the pixel electrode 110 having the comb electrode 1101 is disposed on the first interlayer insulating film 109. . However, on the contrary, the pixel electrode 110 formed in a planar shape may be disposed on the organic passivation film 107, and the comb-shaped common electrode 108 may be disposed on the first interlayer insulating film 109. . However, in the following description, it is assumed that the upper side is the pixel electrode 110 having the comb-tooth electrode 1101 and the lower side is the common electrode 108 which is a flat solid electrode.

  In FIG. 1, a counter substrate 200 is disposed with a liquid crystal layer 300 interposed therebetween. A color filter 201 is formed inside the counter substrate 200. The color filter 201 is formed with red, green, and blue color filters 201 for each pixel, and a color image is formed. A black matrix 202 is formed between the color filters 201 to improve the contrast of the image. Note that the black matrix 202 also has a role as a light shielding film of the TFT, and prevents a photocurrent from flowing through the TFT.

  An overcoat film 203 is formed to cover the color filter 201 and the black matrix 202. Since the surface of the color filter 201 and the black matrix 202 is uneven, the surface is flattened by the overcoat film 203. An alignment film 113 for determining the initial alignment of the liquid crystal is formed on the overcoat film.

  As shown in FIG. 1, in IPS, a conductive film is not formed inside the counter substrate 200. Then, the potential of the counter substrate 200 becomes unstable. Further, external electromagnetic noise enters the liquid crystal layer 300 and affects the image. In order to eliminate such a problem, a surface conductive film 210 is formed outside the counter substrate 200. The surface conductive film 210 is formed by sputtering ITO, which is a transparent conductive film.

  A structure in which liquid crystal is sandwiched between a pixel substrate 110, a TFT substrate 100 in which TFTs and the like are formed in a matrix as shown in FIG. 1, and a counter substrate 200 in which a color filter and the like are formed is referred to as a liquid crystal display panel. In FIG. 1, a backlight 700 is disposed on the back surface of the TFT substrate 100.

  In the electrode arrangement as shown in FIG. 1, even if the potential of the comb-like pixel electrode 110 is higher than the potential of the planar solid common electrode 108 and when it is lower, the flexoelectric is the same. Due to the effect, the transmittance of the liquid crystal layer 300 is different.

  FIG. 2 shows the relative potential of the pixel electrode 110 with respect to the common electrode 108 in frame inversion driving. In FIG. 2, the vertical axis V indicates a voltage applied to the pixel electrode 110 with respect to the common electrode 108 in the case of white display. In FIG. 2, F is a frame period.

  As shown in FIG. 2, the potential of the pixel electrode 110 becomes a positive potential or a negative potential with respect to the common electrode 108 for each frame. Then, due to the flexoelectric effect, the same pixel becomes brighter or darker every frame. This is observed as flicker in the human eye.

  FIG. 3 shows a case where the potential of the pixel electrode 110 is higher than the potential of the common electrode 108. In FIG. 3, the pixel electrode 110 is a comb-like electrode. Under the pixel electrode 110, a common electrode 108 formed in a flat plane with a first interlayer insulating film 109 interposed therebetween is disposed. Both the pixel electrode 110 and the common electrode 108 are formed of a transparent conductive film.

  When the potential of the pixel electrode 110 is higher than the potential of the common electrode 108, the dark line 10 as shown by the shadow in FIG. 3 appears on the comb electrode 1101 of the pixel electrode 110. The luminance of the dark line 10 portion is about 10% to 70% compared to the luminance of other bright portions. In FIG. 3, since there are four comb electrodes 1101, four dark lines 10 are generated.

  FIG. 4 shows a case where the potential of the pixel electrode 110 is lower than the potential of the common electrode 108. In FIG. 4, the pixel electrode 110 is a comb-like electrode. The pixel configuration in FIG. 4 is the same as that described in FIG. When the potential of the pixel electrode 110 is lower than the potential of the common electrode 108, the dark line 10 as shown by the shadow in FIG. 4 appears on the slit 112 between the comb electrode 1101 and the comb electrode 1101 of the pixel electrode 110. In this case, the luminance of the dark line 10 portion is also about 10% to 70% as compared with the luminance of other bright portions. In FIG. 3, since there are three slits 112, three dark lines 10 are generated.

  As described above, the number of the dark lines 10 is different and the brightness of the pixel is different depending on whether the potential of the pixel electrode 110 is higher or lower than the potential of the common electrode 108. In the frame inversion, since the relative potentials of the pixel electrode 110 and the common electrode 108 are switched for each frame, the brightness of the pixel is different for each frame. This is observed as flicker in the human eye.

  FIG. 5 shows the shape of the pixel electrode 110 according to the present invention which counters the above problems. FIG. 5 is a plan view of the pixel as viewed from above the counter substrate 200. In FIG. 5, the black matrix formed on the counter substrate 200 exists on both sides of the pixel. The pixel electrode 110 is divided into two regions having different numbers of comb electrodes 1101. In FIG. 5, four comb electrodes 1101 exist on the upper side of the pixel electrode 110, and three comb electrodes 1101 exist on the lower side. That is, the number of comb-tooth electrodes 1101 is one less on the lower side of the pixel.

  In FIG. 5, the upper comb-tooth electrode 1101 and the lower comb-tooth electrode 1101 of the pixel electrode 110 have the same width w and length l. The width s of the slit 112 is the same on the upper side and the lower side of the pixel electrode 110. A through hole 111 is formed in the upper and lower connecting portions of the pixel electrode 110, and a video signal is supplied to the pixel electrode 110 through the through hole 111. In FIG. 5, a common electrode 108 formed in a flat plane is present below the pixel electrode 110 with a first interlayer insulating film 109 interposed therebetween.

  FIG. 6 is a plan view showing a state in which a higher potential than the common electrode 108 is supplied to the pixel electrode 110 described in FIG. In this case, the dark line 10 appears on the comb electrode 1101 of the pixel electrode 110. Since there are four comb electrodes 1101 on the upper side of the pixel electrode 110, four dark lines 10 are generated. However, on the lower side of the pixel electrode 110, there are three comb electrodes 1101, so there are three The dark line 10 is generated. Therefore, the number of dark lines 10 in the case of FIG. 6 is seven.

  FIG. 7 is a plan view showing a state in which a potential lower than that of the common electrode 108 is supplied to the pixel electrode 110 described with reference to FIG. In this case, the dark line 10 appears on the slit 112 between the comb electrode 1101 and the comb electrode 1101. Since there are three slits 112 on the upper side of the pixel electrode 110, three dark lines 10 are generated. However, on the lower side of the pixel electrode 110, there are four slits 112, so that four dark lines 10 are formed. Arise. Therefore, the number of dark lines 10 in the case of FIG. 7 is also seven as in the case of FIG.

  That is, by using the pixel electrode 110 as shown in FIG. 5, even if frame inversion driving is performed, a change in brightness for each frame can be prevented, and flicker can be prevented.

  In the above description, the pixel electrode 110 formed in the upper layer has been described as a comb electrode, but conversely, the common electrode 108 having the comb electrode 1101 is disposed in the upper layer, and the planar electrode is in the lower layer. Even when the formed pixel electrode 110 is disposed, the present invention can be similarly applied.

  FIG. 8 is a plan perspective view showing a second embodiment of the present invention. In FIG. 8, video signal lines 600 extend in the vertical direction and are arranged in the horizontal direction. Further, the scanning lines 500 extend in the horizontal direction and are arranged in the vertical direction. A region surrounded by the video signal line 600 and the scanning line 500 is a pixel. FIG. 8 shows two pixels.

  In FIG. 8, an upper common electrode 1082 having a comb-tooth electrode 1101 is disposed on the uppermost layer. Below the upper common electrode 1082, the pixel electrode 110 is disposed via the second interlayer insulating film 120. The pixel electrode 110 in FIG. 8 is divided into a region where the comb electrode 1101 is present and a planar solid region. A region where the pixel electrode 110 overlaps the upper common electrode 1082 is a flat solid electrode.

  In the pixel electrode 110, the region where the comb electrode 1101 is formed does not overlap the upper common electrode 1082 but overlaps the common electrode 108 formed below the pixel electrode 110. In FIG. 8, a lower common electrode 1081 formed in a flat plane is disposed below the pixel electrode 110 with a first interlayer insulating film 109 interposed therebetween. The lower flat common electrode 1081 overlaps with the comb electrode 1101 constituting the pixel electrode 110 formed in the upper layer.

  In FIG. 8, the liquid crystal layer 300 present on the upper side is driven by an electric field between the comb-like pixel electrode 110 and the flat common electrode 1081. The liquid crystal layer 300 present on the lower side of FIG. 8 is driven by an electric field between the upper common electrode 1082 having the comb electrode 1101 and the flat pixel electrode 110.

  In FIG. 8, the upper common electrode 1082 and the lower common electrode 1081 are connected outside the display area. When a voltage is applied between the pixel electrode 110 and the common electrode 108, the electric field applied to the liquid crystal molecules 301 in the region having the comb teeth of the pixel electrode 110 and the liquid crystal molecules in the region formed by a flat solid. The direction is different from the electric field applied to 301. Therefore, the flexoelectric effect is opposite in the pixel electrode 110 in the region having the comb teeth and the flat solid region.

  Even when the voltage relationship between the pixel electrode 110 and the common electrode 108 is reversed in the next frame, only the flexoelectric effect is reversed between the comb electrode 1101 portion and the flat solid portion of the pixel electrode 110. Thus, there is no substitute for the existence of a region having the opposite flexoelectric effect within one pixel. Therefore, in this embodiment, since the flexoelectric effect is canceled within one pixel, the luminance does not change even if the frame changes, and flicker does not occur.

  FIG. 9 is a cross-sectional view showing the structure of this embodiment. 9A is a cross-sectional view taken along the line A-A ′ of FIG. 8, and FIG. 9B is a cross-sectional view taken along the line B-B ′. In FIG. 9A, the structure below the lower common electrode 1081 is omitted. The lower common electrode 1081 is a flat solid, and a first interlayer insulating film 109 is formed on the lower common electrode 1081. A comb electrode 1101 of the pixel electrode 110 is formed on the first interlayer insulating film 109. A second interlayer insulating film 120 is formed to cover the pixel electrode 110.

  An alignment film 113 is formed on the second interlayer insulating film 120, but is omitted in FIG. The liquid crystal layer 300 is sandwiched between the TFT substrate 100 and the counter substrate 200 having such a configuration. When a voltage is applied between the comb-like pixel electrode 110 and the lower common electrode 1081, electric lines of force pass from the pixel electrode 110 to the lower common electrode 1081 formed by a plane plane through the slit 112 between the comb-teeth electrodes 1101. The liquid crystal rotates by the lines of electric force, and the amount of transmitted light is controlled.

  FIG. 9B is a cross-sectional view taken along the line B-B ′ of FIG. In FIG. 9B, the structure below the first interlayer insulating film 109 is omitted. A flat solid pixel electrode 110 is formed on the first interlayer insulating film 109. A second interlayer insulating film 120 is formed on the pixel electrode 110, and an upper common electrode 1082 having a comb electrode 1101 is formed on the second interlayer insulating film 120.

  An alignment film 113 is formed on the upper common electrode 1082, but is omitted in FIG. In FIG. 9B, the liquid crystal layer 300 is sandwiched between the TFT substrate 100 and the counter substrate 200. When a voltage is applied between the comb-shaped upper common electrode 1082 and the pixel electrode 110 formed of a flat solid, the upper common electrode 1082 passes through the slit 112 between the comb-shaped electrodes 1101 to the pixel electrode 110 as shown in FIG. A line of electric force in the opposite direction to that of a) is generated, and the liquid crystal rotates by this line of electric force, and the amount of transmitted light is controlled.

  Thus, in FIGS. 9A and 9B, since the direction of the electric field received by the liquid crystal molecules 301 is opposite, the flexoelectric effect is also different in FIGS. 9A and 9B. The reverse is true. That is, the flexoelectric effect is canceled in one pixel.

  FIG. 10 is an exploded plan view of the electrode structure shown in FIG. In FIG. 10, the upper common electrode 1082 is a comb-like electrode. The pixel electrode 110 includes a comb-shaped electrode region and a flat electrode region. The upper common electrode 1082 overlaps the region formed by the planar solid of the pixel electrode 110 with the second interlayer insulating film 120 interposed therebetween. The operation area of the upper common electrode 1082 is half of the operation area of the pixel electrode 110.

  The lower common electrode 1081 is formed as a flat solid, and overlaps the region where the comb electrode 1101 of the pixel electrode 110 is formed via the first interlayer insulating film 109. The operation area of the lower common electrode 1081 is half of the operation area of the pixel electrode 110. The A-A ′ section in FIG. 10 corresponds to FIG. 9A, and the B-B ′ section corresponds to FIG. 9B.

  FIG. 11 shows the flexoelectric effect when a relatively positive voltage is applied to the pixel electrode 110 relative to the upper common electrode 1082 or the lower common electrode 1081. In this case, the dark line 10 due to the flexoelectric effect is generated at the slit 112 portion of the upper common electrode 1082, and the dark line 10 due to the flexoelectric effect is generated at the comb electrode 1101 of the pixel electrode 110. Therefore, the number of dark lines 10 is five. In FIG. 11, the upper common electrode 1082, the pixel electrode 110, and the lower common electrode 1081 are actually overlapped, but are an exploded plan view for explanation.

  FIG. 12 shows the flexoelectric effect when a relatively negative voltage is applied to the pixel electrode 110 relative to the upper common electrode 1082 or the lower common electrode 1081. In this case, the dark line 10 due to the flexoelectric effect is generated at the comb electrode 1101 of the upper common electrode 1082, and the dark line 10 due to the flexoelectric effect is generated at the slit 112 portion of the pixel electrode 110. Therefore, the number of dark lines 10 is five. In FIG. 11, the upper common electrode 1082, the pixel electrode 110, and the lower common electrode 1081 are actually overlapped, but are an exploded plan view for explanation.

  As described above, the number of dark lines 10 is the same regardless of whether a higher voltage or a lower voltage is applied to the pixel electrode 110 than the upper common electrode 1082 or the lower common electrode 1081. Therefore, even when frame inversion driving is performed, the luminance does not change from frame to frame and flicker does not occur.

  In this embodiment, the electrode for driving the liquid crystal requires a total of three layers of electrodes, that is, one pixel electrode 110 and two common electrodes 108. In order to realize such a structure, for example, in FIG. 1, the second interlayer insulating film 120 is formed on the pixel electrode 110, and the upper common electrode 1082 is formed thereon.

  As another method for realizing the three-layer electrode structure, for example, in FIG. 1, the pixel electrode 110 is disposed at the position of the common electrode 108, and the upper common electrode 1082 is disposed at the position of the pixel electrode 110 in FIG. The lower common electrode 1081 can be formed in the same layer as the source electrode or the drain electrode in FIG.

  As another method for realizing the three-layer electrode structure, for example, in FIG. 1, the pixel electrode 110 is disposed at the position of the common electrode 108, and the upper common electrode 1082 is disposed at the position of the pixel electrode 110 in FIG. The lower common electrode 1081 can be formed in the same layer as the gate electrode in FIG.

It is sectional drawing of the liquid crystal display device with which this invention is applied. It is a figure which shows a frame inversion drive. It is an example which shows a flexoelectric effect. It is another example which shows a flexoelectric effect. 3 is a plan view of a pixel electrode of Example 1. FIG. 3 is an example of the operation of the first embodiment. 6 is another example of the operation of the first embodiment. 6 is a perspective view showing an electrode structure of Example 2. FIG. 6 is a cross-sectional view showing an electrode structure of Example 2. FIG. 6 is an exploded view showing an electrode structure of Example 2. FIG. 10 is an example of the operation of the second embodiment. 10 is another example of the operation of the second embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Dark line, 100 ... TFT substrate, 101 ... Gate electrode, 102 ... Gate insulating film, 103 ... Semiconductor layer, 104 ... Source electrode, 105 ... Drain electrode, 106 ... Inorganic passivation film, 107 ... Organic passivation film, 108 ... Common Electrode, 109 ... first interlayer insulating film, 110 ... pixel electrode, 111 ... through hole, 112 ... slit, 113 ... alignment film, 120 ... second interlayer insulating film, 200 ... counter substrate, 201 ... color filter, 202 ... black Matrix, 203 ... Overcoat film, 210 ... Surface conductive film, 300 ... Liquid crystal layer, 301 ... Liquid crystal molecule, 500 ... Scanning line, 600 ... Video signal line, 700 ... Back light, 1081 ... Lower common electrode, 1082 ... Upper common Electrode, 1101 ... Comb electrode.

Claims (8)

Pixels are formed in a region surrounded by the scanning lines extending in the first direction and arranged in the second direction and the video signal lines extending in the second direction and arranged in the first direction. ,
The pixel includes a first electrode formed in a flat plane, an interlayer insulating film formed on the first electrode, and a second electrode formed on the interlayer insulating film,
The second electrode has a first region and a second region, the first region has a first number of comb electrodes, and the second region has a second number of combs. A liquid crystal display device comprising tooth electrodes, wherein the first number and the second number are different.   2. The liquid crystal display device according to claim 1, wherein a difference between the first number and the second number is 1 in the second electrode.   In the second electrode, the length and width of the comb electrode in the first region, and the interval between the comb electrodes are the length and width of the comb electrode in the second region, and The liquid crystal display device according to claim 1, wherein the intervals between the comb electrodes are equal to each other.   The liquid crystal display device according to claim 1, wherein the first electrode is a common electrode, and the second electrode is a pixel electrode. Pixels are formed in a region surrounded by scanning lines extending in the first direction and arranged in the second direction and video signal lines extending in the second direction and arranged in the first direction. ,
The pixel includes: a first electrode formed in a flat plane; a first interlayer insulating film formed on the first electrode; a second electrode formed on the first interlayer insulating film; A third electrode having a second interlayer insulating film formed on the second electrode and a comb electrode formed on the second interlayer insulating film;
The second electrode has a first region where a comb electrode is formed, and a second region where a flat solid electrode is formed,
The region of the second electrode where the comb electrode is formed overlaps with the first electrode, the region of the second electrode where the flat solid electrode is formed overlaps with the third electrode,
The liquid crystal display device, wherein the first electrode and the second electrode have the same potential.   The liquid crystal display device according to claim 5, wherein the number of the comb electrodes formed on the second electrode is equal to the number of the comb electrodes formed on the third electrode.   The length and width of the comb electrode formed on the second electrode, and the interval between the comb electrodes are the length and width of the comb electrode formed on the third electrode, and the comb. The liquid crystal display device according to claim 5, wherein intervals between the tooth electrodes are equal to each other.   The liquid crystal display device according to claim 5, wherein the second electrode is a pixel electrode, and the first electrode and the third electrode are common electrodes.

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