JP2007256980A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve transmittance and contrast of a liquid crystal display device according to FFS method. <P>SOLUTION: A plurality of picture elements, each made of an R pixel, a G pixel and a B pixel, is disposed in a matrix form. In each of the pixels, a gate signal line GL extends in a left to right direction and a display signal line DL extends in a top to bottom direction so as to cross the gate line. A thin film transistor TR for pixel selection is disposed around an intersection of the gate line GL and the display signal line DL. There is provided a pixel electrode 60 connected with the thin film transistor TR. A common electrode 62-1 is provided on the pixel electrode 60 through an insulation film. A plurality of slits S1 having edges at borders between the picture elements is disposed in the common electrode 62-1 to cross each of the picture elements in the left to right direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device in which the alignment direction of liquid crystal molecules is controlled by a horizontal electric field between electrodes on the same substrate.

  As one of the means to increase the viewing angle of liquid crystal display devices, optical switching is performed by generating a horizontal electric field between electrodes on the same substrate and rotating the liquid crystal molecules in a plane parallel to the substrate by this electric field. A method for providing functions has been developed. Examples of this technology include in-plane switching (hereinafter abbreviated as “IPS”), and fringe-field switching (hereinafter referred to as “FFS”), which is an improvement of the IPS system. (Abbreviated) method is known.

  Next, an FFS liquid crystal display device will be described with reference to the drawings. FIG. 12 is a plan view showing an FFS type liquid crystal display device, and FIG. 13 is a cross-sectional view taken along line YY of FIG. In an actual liquid crystal display device, a plurality of pixels are arranged in a matrix, but in these drawings, only one pixel 1P is shown.

  A TFT substrate 10 made of a glass substrate or the like is disposed facing the light source BL. A first polarizing plate 11 that linearly polarizes light from the light source BL is formed on the surface of the TFT substrate 10 facing the light source BL. A buffer film 12 made of a silicon oxide film or a silicon nitride film is formed on the opposite surface of the TFT substrate 10.

  An active layer PS made of polysilicon or the like is formed on the buffer film 12 in the formation region of the pixel selection thin film transistor TR. On the buffer film 12, a gate insulating film 13 made of a silicon oxide film, a silicon nitride film or the like and covering the active layer PS is formed. A gate line GL is formed on the gate insulating film 13 so as to face the active layer PS. The gate line GL is made of a metal containing chromium or molybdenum. On the gate insulating film 13, a common potential line COM made of a metal containing chromium or molybdenum or the like for supplying a common potential is formed. The gate line GL, the common potential line COM, and the gate insulating film 13 are covered with an interlayer insulating film 14.

  The interlayer insulating film 14 is provided with a contact hole CH1 exposing the source region of the active layer PS and a contact hole CH2 exposing the drain region. The interlayer insulating film 14 is provided with a contact hole CH3 exposing the common potential line COM.

  A display signal line DL connected to the source region of the active layer PS through the contact hole CH1 is formed on the surface of the interlayer insulating film. A drain electrode 15 connected to the drain region of the active layer PS through the contact hole CH2 is formed on the surface of the interlayer insulating film. A pad electrode 16 connected to the common potential line COM through the contact hole CH3 is formed on the surface of the interlayer insulating film. The display signal line DL, the drain electrode 15 and the pad electrode 16 are made of a metal containing aluminum or an aluminum alloy. Further, the display signal line DL, the drain electrode 15, the pad electrode 16, and the interlayer insulating film 14 are covered with a passivation film 58.

  A planarizing film 59 is formed on the passivation film 58. The passivation film 58 and the planarizing film 59 are provided with a contact hole CH5 exposing the drain electrode 15 and a contact hole CH6 exposing the pad electrode 16.

  On the planarizing film 59, a pixel electrode 60 is formed which is connected to the drain electrode 15 through the contact hole CH5 and made of a first layer transparent electrode such as ITO. A voltage corresponding to the display signal is applied to the pixel electrode 60. In addition, an insulating film 61 is formed on the pixel electrode 60 to cover it. On the insulating film 61, a common electrode 62 having a plurality of slits S extending in parallel and made of a second layer transparent electrode such as ITO is formed. The common electrode 62 is connected to the pad electrode 16 through the contact hole CH6. An alignment film (not shown) that covers the common electrode 62 is formed on the insulating film 61.

  Further, a color filter substrate (hereinafter abbreviated as “CF substrate”) 20 made of a glass substrate or the like is disposed facing the TFT substrate 10. A color filter and an alignment film (not shown) are formed on the surface of the CF substrate 20 facing the TFT substrate 10. A second polarizing plate 21 is formed on the surface of the CF substrate 20 on the side not facing the TFT substrate 10. The first and second polarizing plates 11 and 21 are arranged so that the polarizing axes of the polarizing plates are orthogonal to each other. A liquid crystal 30 is sealed between the TFT substrate 10 and the CF substrate 20.

  In the liquid crystal display device, in a state where no display voltage is applied to the pixel electrode 60 (no-voltage state), the average alignment direction of the major axis of the liquid crystal molecules of the liquid crystal 30 (hereinafter simply referred to as “alignment direction”). The inclination is parallel to the polarization axis of the first polarizing plate 11. At this time, the linearly polarized light transmitted through the liquid crystal 30 is not emitted from the second polarizing plate 21 because its polarization axis is orthogonal to the polarizing axis of the second polarizing plate 21. That is, the display state is black display. (Normally black)

On the other hand, when a display voltage is applied to the pixel electrode 60, an electric field is generated from the common electrode 62 to the lower pixel electrode 60 through the slit S. (See the arrow in FIG. 13) When viewed in a plan view, this electric field is an electric field perpendicular to the longitudinal direction of the slit S, and the liquid crystal molecules rotate along the electric lines of force of the electric field. (Refer to the arrow in FIG. 12) At this time, the linearly polarized light incident on the liquid crystal 30 becomes elliptically polarized light due to birefringence, but has a linearly polarized light component transmitted through the second polarizing plate 21, and the display in this case The state is displayed in white. Note that the FFS liquid crystal display device is described in Patent Document 1 below.
JP 2002-296611 A

  When a display voltage is applied to the pixel electrode 60 as described above, electric lines of force perpendicular to the longitudinal direction of the slit S are generated in the slit central portion SC of FIG. 12, but this is different from the edge SE of the slit S. Electric field lines in the direction are generated. The alignment direction of the liquid crystal molecules is different from the slit central portion SC, and a liquid crystal portion having a different alignment direction becomes a domain (a portion surrounded by a circle in FIG. 12). Such a defect in alignment of liquid crystal molecules is called disclination. Due to this disclination, there is a problem that optical characteristics are deteriorated, that is, normally black causes a decrease in local transmittance and contrast.

  Therefore, the liquid crystal display device of the present invention includes a plurality of pixels, and each pixel is provided with a thin film transistor, a pixel electrode connected to the thin film transistor, an insulating film on the pixel electrode, and a common potential supplied thereto. A common electrode, wherein at least one slit extending across the plurality of pixels is opened in the common electrode.

  According to the liquid crystal display device of the present invention, since the slit of the common electrode extends across the plurality of pixels, the number of slit edges existing in the pixel is reduced, and the transmittance due to disclination is reduced. , The reduction in contrast can be suppressed.

First Embodiment A liquid crystal display device according to a first embodiment of the present invention will be described with reference to FIG. 1, the same components as those in FIG. 12 are denoted by the same reference numerals. A plurality of pixels are arranged in a matrix on the TFT substrate, with three pixels corresponding to red, green and blue (hereinafter referred to as R pixel, G pixel and B pixel, respectively) as one pixel. In each of the R pixel, G pixel, and B pixel, the gate line GL extends in the left-right direction (horizontal direction), and the display signal line DL extends in the vertical direction (vertical direction) so as to intersect the gate line GL. ing. A thin film transistor TR is disposed near the intersection of the gate line GL and the display signal line DL, and a pixel electrode 60 connected to the thin film transistor TR for pixel selection is provided. A common electrode 62-1 is provided on the pixel electrode 60 via an insulating film. The common electrode 62-1 is connected to a common potential line COM extending in the left-right direction.

  The common electrode 62-1 has a plurality of slits S1 that linearly extend in the left-right direction, that is, in a direction orthogonal to the display signal line DL, and have an edge SE1 at each pixel boundary. Has been. The direction in which the slit S1 is opened need not be a direction that is exactly orthogonal to the display signal line DL, and may be a direction that is substantially orthogonal, for example, about 5 degrees obliquely from the left-right direction (lateral direction). You may tilt.

  By providing such a slit S1, the edge SE1 of the slit S1 existing in each pixel is reduced, and the decrease in transmittance and contrast due to disclination can be suppressed. In particular, by arranging the G pixel having a large influence on the transmittance and contrast in the center of the picture element, the edge SE1 of the slit S1 does not exist for the G pixel, so that the transmittance and contrast can be maximized. Note that the liquid crystal is sealed between the TFT substrate and the CF substrate as in the conventional example.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIG. 2, the same components as those in FIG. 12 are denoted by the same reference numerals. Also in this embodiment, a plurality of picture elements are arranged in a matrix with three pixels of R pixel, G pixel, and B pixel as one picture element, but FIG. 2 shows only four pixels.

  The difference from the first embodiment is that a plurality of slits S2 are opened in the common electrode 62-2, and each slit S2 has a width of two pixels (a horizontal width of the pixel, in other words, a horizontal width). The slit S2 extends in the left-right direction only, and such a slit S2 is shifted in the left-right direction by a width of one pixel and is arranged in the up-down direction. That is, the slit S2 in the second row below the slit S2 in the first row is shifted in the left-right direction by one pixel width with respect to the slit S2 in the first row. Further, the slit S2 in the lower third row is shifted in the horizontal direction by one pixel width with respect to the slit S2 in the second row, and as a result, is the same as the slit S2 in the first row.

  In this way, when viewed with one pixel, the number of edges SE2 of the slit S2 is ½ that of the conventional example (FIG. 12). By reducing the number of edges SE2 of the slit S2, the transmittance can be increased and the contrast can be improved.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIG. 3, the same components as those in FIG. 12 are denoted by the same reference numerals. In this embodiment as well, a plurality of picture elements are arranged in a matrix with three pixels of R pixel, G pixel, and B pixel as one picture element, but FIG. 3 shows only five pixels.

  The difference from the first embodiment is that a plurality of slits S3 are opened in the common electrode 62-3, and each slit S3 extends in the left-right direction by a width of 3 pixels. The point is that they are arranged in the vertical direction, shifted in the horizontal direction by the width of one pixel. That is, the slit S3 in the second row below the slit S3 in the first row is shifted to the right by one pixel width with respect to the slit S3 in the first row. Further, the slit S3 in the lower third row is shifted to the right by the width of one pixel with respect to the slit S3 in the second row. Further, the slit S3 in the lower fourth row is shifted to the right by the width of one pixel with respect to the slit S3 in the third row, and as a result, becomes the same as the slit S3 in the first row.

  In this way, when viewed with one pixel, the number of edges SE3 of the slit S3 is 1/3 of the conventional example (FIG. 12). By reducing the number of edges SE3 of the slit S3, the transmittance can be increased and the contrast can be improved.

  According to the second and third embodiments, by further extending the slit length of the common electrode so as to be equal to the width of four pixels or more, the number of slit edges in one pixel is It can be further reduced. However, as the length of the slit is extended, the stripe-shaped common electrode wired in the pixel is also extended in the left-right direction, and the resistance is increased. Then, the potential of the common electrode is distorted during the operation, and the display quality is lowered due to crosstalk or the like. Therefore, it is preferable to suppress the length of the slit to such a length that does not cause problems such as crosstalk.

Therefore, the number of edges for each pixel is made the same. If the limit of the length of such a slit is defined by the width of N pixels, N is the largest natural number among X satisfying the following expression.
L-TBM ≧ (l + s) × X
L is the vertical pixel pitch (μm), TBM is the vertical black matrix width (μm), l is the slit line width (μm), and s is the slit space width (μm).

  For example, when L = 150 μm, TBM = 20 μm, and l + s = 6.5 μm, X ≦ 20, and the limit N of the slit length is 20. In the above case, each slit extends in the left-right direction by a width of 20 pixels, and is shifted in the left-right direction by a width of one pixel, so that the number of edges per pixel is 1. The edges of each pixel are even.

Fourth Embodiment A fourth embodiment of the present invention will be described with reference to FIG. In FIG. 4, the same components as those in FIG.

  According to the first, second, and third embodiments, the slits S1, S2, and S3 of the plurality of common electrodes extend linearly in a direction orthogonal to the display signal line DL and cross the plurality of pixels. However, in the present embodiment, the slits S4 of the plurality of common electrodes 62A extend in parallel to the display signal lines DL and cross a plurality of pixels arranged in the vertical direction (vertical direction). The slits S4 of the plurality of common electrodes 62A may not be completely parallel to the display signal line DL, but may be substantially parallel, for example, may be inclined about 5 degrees from the vertical direction (vertical direction).

  Since the pixels are long in the vertical direction, using a vertical slit can reduce the number of slit edges compared to using a horizontal slit. Compared with the slits S1, S2, S3 extending in the direction), the transmittance and the like can be improved.

  On the other hand, when the slit S4 is used, if the pixel electrode is a second-layer transparent electrode such as ITO, one of the pixels adjacent in the left-right direction displays white and the other displays black. Under the influence of the electric field, the end of the black display pixel is caused to pass through, and a color mixing problem occurs in which the colors of adjacent pixels are mixed.

  In order to avoid this, in the present embodiment, the pixel electrode 60 is formed of a first transparent electrode such as ITO, and the common electrode 62A is formed of a second transparent electrode such as ITO. Even when such a slit S4 is used, the edge of the slit S4 exists at the boundary of the pixel, and there is still a problem that the transmittance is lowered due to disclination generated at the edge.

  Therefore, in the present embodiment, the slit S4 is made to cross all the pixels in the vertical direction (vertical direction) of the display area. As a result, the edge of the slit S4 disappears in the pixel, and the transmittance is not reduced due to disclination.

Fifth Embodiment A fifth embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a layout diagram of a pixel, and FIG. 6 is a cross-sectional view taken along line XX of FIG. 5 and 6, the same components as those in FIGS. 12 and 13 are denoted by the same reference numerals.

  This embodiment is different from the fourth embodiment in that a slit S4 is provided on the pixel contact portion to prevent a short circuit between the pixel electrode 60 and the common electrode 62A.

  As shown in FIG. 6, the drain electrode 15 of the thin film transistor TR is connected to the pixel electrode 60 through a contact hole CH <b> 5 formed in the passivation film 58 and the planarization film 59. A common electrode 62 </ b> A is formed on the pixel electrode 60 via an insulating film 61. However, since the step coverage of the insulating film 61 is deteriorated in the contact hole CH5 portion, if the common electrode 62A exists on the contact hole CH5, the insulating film 61 is locally thinned or missing, and the common electrode 62A And the pixel electrode 60 may be short-circuited. Therefore, the slit S4 of the common electrode 62A is provided on the contact hole CH5 to prevent a short circuit between the common electrode 62A and the pixel electrode 60.

Sixth Embodiment A sixth embodiment of the present invention will be described with reference to FIG. 7, the same components as those in FIG. 12 are denoted by the same reference numerals. The common electrode 62A is connected to the pad electrode 16 through the contact hole CH6. The pad electrode 16 is connected to the common potential line COM through the contact hole CH3.

  Therefore, if there is no common electrode 62A over the contact hole CH6, contact between the pad electrode 16 and the common electrode 62A cannot be obtained. Therefore, in the present embodiment, the slit S4 is cut on the contact portion between the common electrode 62A and the pad electrode 16, that is, the common electrode 62A is left without providing the slit S4. Thus, the common electrode 62A can be reliably connected to the common potential line COM via the pad electrode 16.

Seventh Embodiment A seventh embodiment of the present invention will be described with reference to FIG. 8, the same components as those in FIG. 12 are denoted by the same reference numerals. In the sixth embodiment, the contact portion between the common electrode 62A and the common potential line COM is provided in all the pixels of the R pixel, the G pixel, and the B pixel. However, when such a contact portion is provided, the pixel This causes a problem that the aperture ratio decreases and the transmittance decreases. Therefore, in this embodiment, the transmittance is reduced by providing the contact portion between the common electrode 62A and the common potential line COM for only one of the R pixel, G pixel, and B pixel. It is the one that has been suppressed. Since the B pixel is less sensitive than other color pixels and is not easily affected by a decrease in transmittance, the contact portion is provided only for the B pixel or mainly for the B pixel. Is preferred. Thus, by providing the contact portion mainly for the B pixel, the transmittance of the R pixel and the G pixel can be improved, and the influence of the B pixel can be minimized although the transmittance of the B pixel is lowered.

Eighth Embodiment An eighth embodiment of the present invention will be described with reference to FIG. 9, the same components as those in FIG. 12 are denoted by the same reference numerals. In the present embodiment, the common potential line COM is deleted from the pixel in order to improve the aperture ratio of the pixel. The end portion of the common electrode 62A is disposed on the outer periphery of the display area, and is connected to the outer peripheral common potential line to which the common potential Vcom is supplied. Then, when the slit S4 of the common electrode 62A is made to cross all the pixels in the vertical direction (vertical direction) of the display area as in the fourth to seventh embodiments, the common electrode 62A becomes a very elongated wiring, Since the resistance increases and the relaxation time for returning the distortion of the common potential signal supplied to the common electrode 62A becomes longer, display anomalies such as crosstalk may occur.

  Therefore, in the present embodiment, the slit S4 of the common electrode 62A is not traversed by all the pixels in the vertical direction (vertical direction) of the display area, and the maximum number of pixels traversed by the slit S4 is within one pixel. The number of slits S4. In the layout example of FIG. 9, since the number of slits S4 in one pixel is five, the maximum number of pixels traversed by the slit S4 is five. Thereby, occurrence of display abnormality such as crosstalk can be prevented.

Ninth Embodiment A ninth embodiment of the present invention will be described with reference to FIG. 10, the same components as those in FIG. 12 are denoted by the same reference numerals. In the eighth embodiment, the slit S4 of the common electrode 62A that crosses a plurality of pixels is cut at the same pixel boundary. In contrast, in the present embodiment, each slit S4 is cut at a separate pixel boundary, that is, the edge SE4 of the slit S4 is arranged at a separate pixel boundary to prevent display unevenness from occurring. It is. Of course, the configuration of the present embodiment may be added to the configuration of the eighth embodiment.

Tenth Embodiment A tenth embodiment of the present invention will be described with reference to FIG. 11, the same components as those in FIG. 12 are denoted by the same reference numerals. In the ninth embodiment, the slit S4 of the common electrode 62A is further provided on the pixel contact portion in the ninth embodiment to prevent a short circuit between the pixel electrode 60 and the common electrode 62A. (Contact structure similar to FIG. 6)

  In the eighth to tenth embodiments in which the common potential line COM is deleted, it is preferable to delete all or part of the left-right (horizontal) black matrix arranged at the pixel boundary. This is because according to the present invention, since the number of slit edges is reduced and display abnormality due to disclination is suppressed, it is not necessary to shield the disclination portion with a black matrix.

  In this case, the black matrix is preferably installed in a stepped portion such as a pixel contact portion (a contact portion between the drain electrode 15 of the thin film transistor TR and the pixel electrode 60). This is because a step occurs in the pixel contact portion, and the alignment of liquid crystal molecules is disturbed to cause light leakage. In such a step portion, it is effective to prevent light leakage by a black matrix. is there.

  In the first to third embodiments, the pixel arrangement method is a stripe arrangement. However, the present invention can also be applied to a delta arrangement pixel arrangement in which a plurality of pixels are arranged to be shifted from each other. For example, the slit of the common electrode is provided so as to cross a plurality of pixels arranged in a delta arrangement.

  The first to third embodiments are different from the fourth to tenth embodiments in the direction in which the slit of the common electrode extends, but other features are different from those of the other embodiments. Can be added to the configuration.

  In the first to tenth embodiments, a plurality of slits extending across the plurality of pixels are opened in the common electrode, but one slit extends across the plurality of pixels. It may be only.

  In the fourth to tenth embodiments, since the slit S4 is connected in the vertical direction (vertical direction), the electric field of the gate line GL affects the liquid crystal layer through the slit S4. In this case, a so-called burn-in problem occurs and the display quality is lowered. Therefore, it is preferable that one of the pixel electrodes 60 in the vertical direction with respect to the gate line GL extends to the gate line GL so that the electric field of the gate line GL can be shielded.

  Even when the slits S1, S2, and S3 are connected to the display signal line DL in the left-right direction (lateral direction) as in the first to third embodiments, the display signal line DL is connected to the display signal line DL for the same reason as described above. On the other hand, it is preferable to extend one of the pixel electrodes 60 in the left-right direction to the display signal line DL. However, in the case of the display signal line DL, the polarity is inverted with respect to the common potential Vcom, and the signal is almost symmetrical Therefore, it is not always necessary to extend the pixel electrode 60 over the display signal line DL.

1 is a pixel layout diagram of a liquid crystal display device according to a first embodiment of the present invention; FIG. 6 is a pixel layout diagram of a liquid crystal display device according to a second embodiment of the present invention. FIG. 6 is a pixel layout diagram of a liquid crystal display device according to a third embodiment of the present invention. It is a layout diagram of the pixel of the liquid crystal display device by the 4th Embodiment of this invention. FIG. 10 is a pixel layout diagram of a liquid crystal display device according to a fifth embodiment of the present invention. FIG. 6 is a cross-sectional view taken along line XX in FIG. 5. It is a layout diagram of the pixel of the liquid crystal display device by the 6th Embodiment of this invention. It is a layout diagram of the pixel of the liquid crystal display device by the 7th Embodiment of this invention. It is a layout diagram of the pixel of the liquid crystal display device by the 8th Embodiment of this invention. It is a layout diagram of the pixel of the liquid crystal display device by the 9th Embodiment of this invention. It is a layout diagram of the pixel of the liquid crystal display device by the 10th Embodiment of this invention. It is a top view of one pixel of the liquid crystal display device of a prior art example. It is sectional drawing along the YY line of FIG.

Explanation of symbols

1P pixel 10 TFT substrate 11 first polarizing plate 12 buffer film 13 gate insulating film 14 interlayer insulating film 15 drain electrode 16 electrode 20 CF substrate 21 second polarizing plate 30 liquid crystal layer 58 passivation film 59 flattening film 60 pixel electrode 61 Insulating films 62, 62-1, 62-2, 62-3, 62A Common electrode BL Light source CH1, CH2, CH3, CH4, CH5, CH6 Contact hole COM Common potential line DL Display signal line GL Gate line PS Active layer S, S1, S2, S3, S4 Slit SC Slit center part SE, SE1, SE2, SE3 SE4 Edge TR Thin film transistor

Claims (13)

With multiple pixels,
Each pixel includes a thin film transistor, a pixel electrode connected to the thin film transistor, and a common electrode disposed on the pixel electrode via an insulating film and supplied with a common potential.
The liquid crystal display device, wherein the common electrode has at least one slit extending across a plurality of pixels.   2. The liquid crystal display device according to claim 1, wherein the plurality of slits extend substantially parallel to display signal lines that supply display signals to the pixels through the thin film transistors.   The liquid crystal display device according to claim 1, wherein the plurality of slits extend in a direction substantially orthogonal to a display signal line that supplies a display signal to the pixel through the thin film transistor. The plurality of pixels includes three pixels corresponding to red, green, and blue, and the three pixels are used as one pixel, and a plurality of pixels are arranged.
4. The liquid crystal display device according to claim 1, wherein the plurality of slits traverse each pixel and have an edge at a boundary between the pixels.   The liquid crystal display device according to claim 4, wherein a pixel corresponding to green is arranged at a center of the picture element.   A plurality of slits extending in the first direction by the width of N pixels (N is a natural number of 2 or more) are arranged in the second direction by shifting the width of one pixel in the first direction by the common electrode. 6. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is a liquid crystal display device. The liquid crystal display device according to claim 6, wherein the N is a maximum natural number among X satisfying the following inequality.
L-TBM ≧ (l + s) × X
L is the pitch (μm) of the pixels in the second direction, TBM is the width of the black matrix (μm) in the second direction, l is the line width (μm) of the slit, and s is the space of the slit. The width (μm).   The first contact portion for connecting the thin film transistor and the pixel electrode is provided, and the slit of the common electrode is provided on the first contact portion. , 6 or 7 liquid crystal display device.   A common potential line that is provided in the plurality of pixels and supplies a common potential; and a second contact portion that connects the common potential line and the common electrode. A slit of the common electrode is provided on the second contact portion. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is not provided.   10. The liquid crystal display device according to claim 9, wherein the second contact portion is provided mainly in a pixel of one color among pixels corresponding to a plurality of colors.   The liquid crystal display device according to claim 10, wherein the one color is blue.   4. The liquid crystal according to claim 1, wherein when the number of the plurality of slits in one pixel is M, the plurality of slits traverse at most M pixels. Display device.   13. The liquid crystal display device according to claim 1, wherein edges of the plurality of slits are located at boundaries between different pixels, respectively.

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