JP5278337B2 - Liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve high-quality display without inducing disclination within an aperture region of a pixel. <P>SOLUTION: An insulating layer is provided on a first substrate 1, corresponding to a portion where pixel electrodes 3 are adjoining to each other, the insulating layer protruding from the face where the pixel electrodes are formed toward a second substrate 2. The pixel electrode 3 is formed in such a manner that a first edge 3a in a prescribed side of the pixel electrode is laid under the insulating layer 16 in the first edge side, and a second edge 3b of the pixel electrode in the opposite side to the first edge 3a is superimposed on the insulating layer 16 in the second edge side. A first alignment layer 17 formed to cover the pixel electrode 3 and the insulating layer 16 is rubbed in a direction from the first edge 3a to the second edge 3b of the pixel electrode 3. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a liquid crystal display element.

As the liquid crystal display element, there is an active matrix type using a thin film transistor as a switching element. The active matrix liquid crystal display element includes a first substrate on which a plurality of pixel electrodes to which data signals are supplied via thin film transistors are arranged, a second substrate on which a common electrode facing each pixel electrode is formed, It is constituted by a liquid crystal sealed between the first substrate and the second substrate.

Note that the the first substrate wherein the first alignment film covering the pixel electrode is formed, the said second substrate being a second alignment film covering the opposing electrode is formed, these alignment films Are each rubbed in a predetermined direction.

  The liquid crystal molecules are aligned in an initial alignment state pretilted toward the downstream side (rubbing end side) of the first alignment film and the second alignment film with respect to each substrate.

  The liquid crystal display element applies a driving electric field having a strength corresponding to the potential of the data signal between each pixel electrode and the common electrode by supplying a data signal to each pixel electrode. Display is performed by changing the alignment state of the liquid crystal molecules.

  In the liquid crystal display element, an electric field having a strength corresponding to the difference between the potential of one pixel electrode and the potential of the other pixel electrode (hereinafter referred to as a lateral electric field) is generated between adjacent pixel electrodes.

  Therefore, the direction of the driving electric field applied between the pixel electrode and the common electrode is inclined with respect to the normal direction of the substrate in the region corresponding to the vicinity of the edge of the pixel electrode due to the influence of the lateral electric field. Distorted in an inclined direction. The directions of distortion of the drive electric field due to the lateral electric field are opposite to each other on one edge side of the pixel electrode and the opposite edge side.

  Therefore, the liquid crystal molecules in the region near the edge facing the upstream side in the rubbing direction of the first alignment film (the rubbing start end side) of the peripheral edge of the pixel electrode are caused by distortion of the direction of the driving electric field, It rises in the direction of tilting in the direction opposite to the direction of the pretilt to generate disclination.

  This display defect due to disclination is made inconspicuous by forming a light-shielding film provided on the second substrate so as to face the region between the pixel electrodes so as to cover the disclination generation region. Can do. However, if the light shielding film is formed wide, the aperture ratio of the pixel is lowered.

  Therefore, as described in Patent Document 1, an insulating layer that protrudes to the second substrate side from the formation surface of each pixel electrode is provided in a portion where each pixel electrode on the first substrate is adjacent to each other. There has been proposed a liquid crystal display element in which an edge portion of the pixel electrode intersecting the rubbing direction of the first alignment film is formed on the insulating layer.

  In this liquid crystal display element, by reducing the distance between the edge of the pixel electrode and the common electrode, it is possible to reduce the distortion of the direction of the driving electric field due to the influence of the lateral electric field generated between adjacent pixel electrodes.

JP 2002-156646 A

  However, the liquid crystal display element described in Patent Document 1 may generate disclination in the opening area of the pixel.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display element capable of displaying a good quality without generating disclination in an opening area of a pixel.

In order to solve the above problems, one embodiment of the liquid crystal display element of the present invention is a first substrate formed by arranging a plurality of pixel electrodes to which a data signal is supplied via a thin film transistor, and faces each of the pixel electrodes. a second substrate having a common electrode is formed, a liquid crystal sealed between said first substrate second substrate is constituted by, by applying a voltage to between the common electrode and the pixel electrode In the liquid crystal display element that displays by changing the alignment state of the liquid crystal molecules, the second electrodes are formed on the first substrate so as to correspond to the portions where the pixel electrodes are adjacent to each other. insulating layer is provided protruding to the substrate side, wherein each pixel electrode, allowed to enter the first edge of the predetermined side below the insulating layer of those said one edge side, said first edge those wherein the second edge side of the second edge portion opposite to The formed overlying the insulating layer, is formed to cover the front Symbol first alignment film and the common electrode on the second substrate having the formed covering the pixel electrodes and the insulating layer on the first substrate The first alignment film of the second alignment film is rubbed in a direction from the second edge of the pixel electrode toward the first edge, and a compensation capacitor is formed on the second edge of the pixel electrode. And the first edge portion of the pixel electrode and the compensation capacitor forming portion are formed on the insulating layer on the first edge side and on the second edge side. The first transparent conductive film formed in a shape projecting from the bottom of the insulating layer to the outside, the portion between the first edge and the compensation capacitance forming portion and the second edge, It has a second transparent conductive film formed on the overhanging portion of the first transparent conductive film and the insulating layer. , Characterized in that.

  According to the liquid crystal display element of the present invention, even if the potential difference between the data signals supplied to the adjacent pixel electrodes is large, a good quality display can be performed without generating disclination in the opening area of the pixel. Can do.

The top view which abbreviate | omitted the one part orientation film of the 1st board | substrate of the liquid crystal display element which shows 1st Example of this invention. Sectional drawing of the said liquid crystal display element which follows the II-II arrow line of FIG. The expanded sectional view of the part in which the insulating layer was formed in the liquid crystal display element of a 1st Example. The schematic diagram of the liquid crystal molecular orientation at the time of no electric field in the liquid crystal display element of a 1st Example. The schematic diagram of the liquid crystal molecular orientation at the time of the electric field application in the liquid crystal display element of 1st Example. The schematic diagram of the liquid crystal molecular orientation at the time of the electric field application in the liquid crystal display element of a comparative example. FIG. 6 is a cross-sectional view of a part of a liquid crystal display device showing a second embodiment of the present invention. The expanded sectional view of the part in which the insulating layer was formed in the liquid crystal display element of a 2nd Example. The schematic diagram of the liquid crystal molecular orientation at the time of the electric field application in the liquid crystal display element of a 2nd Example. Sectional drawing of the part of liquid crystal display element which shows 3rd Example of this invention. The expanded sectional view of the part in which the insulating layer was formed in the liquid crystal display element of a 3rd Example. The figure which shows typically the orientation state of the liquid crystal molecule at the time of the electric field application in the liquid crystal display element of a 3rd Example. Sectional drawing of the part in which the insulating layer of the liquid crystal display element which shows 4th Example of this invention was formed. Sectional drawing of the part in which the insulating layer of the liquid crystal display element which shows 5th Example of this invention was formed. Sectional drawing of the part in which the insulating layer of the liquid crystal display element which shows 6th Example of this invention was formed.

[First embodiment]
The liquid crystal display element of the present invention is an active matrix liquid crystal display element using a thin film transistor (hereinafter referred to as TFT) as a switching element, and a pixel electrode to which a data signal is supplied via a TFT 4 as shown in FIGS. 3 is a first substrate 1 formed to cause a plurality of sequences (vertical direction in FIG. 1) and a column direction (the lateral direction in FIG. 1) row, a common electrode 20 facing the pixel electrode 3 is formed the the second substrate 2, a liquid crystal 22 sealed between the first substrate 1 and the second substrate 2, and is composed of a.

  Each of the first substrate 1 and the second substrate 2 is made of a transparent plate such as a glass plate, and these substrates 1 and 2 are arranged to face each other with a predetermined gap and surround the arrangement region of the pixel electrodes. It is joined via a frame-shaped sealing material (not shown) formed in the above. The liquid crystal 22 is a nematic liquid crystal having positive dielectric anisotropy, and is sealed in a region surrounded by the sealing material in the gap between the first substrate 1 and the second substrate 2.

  On the surface of the first substrate 1 facing the second substrate 2, TFTs 4 are formed corresponding to the formation positions of the respective pixel electrodes 3, and scanning signal lines 10 connected to the TFTs 4 and A data signal line 11 is provided.

  As shown in FIG. 1, the TFT 4 includes a gate electrode 5 formed on the first substrate 1, a gate insulating film 6 covering the gate electrode 5, and the gate electrode 5 on the gate insulating film 6. A semiconductor thin film 7 made of genuine amorphous silicon formed so as to face each other, a channel protective film (not shown) provided at the center of the upper surface of the semiconductor thin film 7, and a channel region of the semiconductor thin film 7 sandwiched therebetween, A source electrode 8 and a drain electrode 9 are formed on one side and the other side via contact layers (not shown) made of n-type amorphous silicon. The gate insulating film 6 is made of a transparent film, and is formed over substantially the entire first substrate 1.

  The scanning signal line 10 is formed on the first substrate 1. The scanning signal line 10 is extended and wired in a row direction in a region on one side of the pixel electrode 3 in each row, and is connected to the gate electrode 5 of each TFT 4 in the corresponding row. The scanning signal line 10 is formed integrally with the gate electrode 5.

  The data signal line 11 is formed on the gate insulating film 6. The data signal lines 11 are wired to extend in the column direction in a region on one side of the pixel electrodes 3 in each column, and branch lines 11a led out from the data signal line 11 to the TFT arrangement portion in each column. Are connected to the source electrode 8 of each TFT 4 in the corresponding column. The data signal line 11 and the branch line 11a are formed integrally with the source electrode 8.

  Further, a transparent interlayer insulating film 12 is formed on the surface of the first substrate 1 on which the TFTs 4 and the data signal lines 11 are formed. The transparent interlayer insulating film 12 is formed on the interlayer insulating film 12. Between each of the pixel electrodes 3, a capacitor electrode 13 that forms a compensation capacitor Cs (see FIG. 3) for compensating for a variation in potential of the pixel electrode 3 is provided.

  The capacitor electrode 13 is opposed to each pixel electrode 3 arranged in the row direction for each row of the pixel electrodes 3, and the capacitor electrodes 13 and 13 respectively opposed to the pixel electrodes 3 are connected in common. Is formed.

  In this embodiment, the capacitor electrode 13 is formed in a frame shape that opposes substantially the entire region of the peripheral portion of the pixel electrode 3 excluding the connection portion with the TFT 4. Furthermore, a side portion (hereinafter, referred to as a vertical side portion) 13 a that intersects the row direction of the pixel electrode 3 among the side portions of the capacitive electrode 13 is a vertical side portion of adjacent capacitive electrodes 13 in the same row. It is integrally formed with 13a. That is, the capacitor electrodes 13 and 13 that face the pixel electrodes 3 arranged in the row direction are connected to each other at the vertical side portion 13a. The capacitor electrodes 13 in each row are connected in common outside the array region of the pixel electrodes 3.

  The vertical side portion 13a of each capacitor electrode 13 is formed to have a width in which the edge portions on both sides of the vertical side portion 13a are opposed to both the adjacent edge portions of each pixel electrode 3 arranged in the row direction. Has been. That is, the vertical side portion 13 a of the capacitor electrode 13 is formed so as to cover a portion on the data signal line 11.

  Further, a transparent overcoat insulating film 14 is provided on the first substrate 1 so as to cover the capacitor electrode 13, and a transparent conductive material such as an ITO film is formed on the overcoat insulating film 14. A plurality of pixel electrodes 3 made of a film are formed. Each pixel electrode 3 is connected to the drain electrode 9 of the TFT 4 corresponding to the pixel electrode 3 in a contact hole 15 (see FIG. 1) provided in the overcoat insulating film 14 and the interlayer insulating film 12. .

  Further, the pixel electrodes 3 arranged in the row direction intersecting with the data signal lines 11 are formed on the first substrate 1 so as to correspond to portions adjacent to each other, and are the formation surfaces of the pixel electrodes 3. A band-shaped insulating layer 16 is provided so as to protrude toward the second substrate 2 from the film surface of the overcoat insulating film 14. The insulating layer 16 is formed in a portion on the vertical side portion of the capacitor electrode 13 so as to have substantially the same width as the vertical side portion. In this embodiment, the insulating layer 16 is formed in a continuous shape over the entire length of the array region of the pixel electrodes 3 in the column direction. However, the insulating layer 16 is formed for each row of the pixel electrodes 3. Each pixel electrode 3 may be formed to have a length that extends over substantially the entire length of adjacent portions.

  Each of the pixel electrodes 3 causes a first edge 3a on a predetermined side of the peripheral edge thereof to enter under the insulating layer 16 on the first edge 3a side, and the first edge 3a. The second edge 3b on the opposite side is formed on the insulating layer 16 on the second edge 3b side.

Each pixel electrode 3 is formed in a rectangular shape having two horizontal sides parallel to the row direction and two vertical sides parallel to the column direction. In this embodiment, the first edge 3a along the right vertical side in the drawing of the pixel electrode 3 is made to enter under the insulating layer 16 on the first edge 3a side. A second edge 3b along the side is overlaid on the insulating layer 16 on the second edge 3b side.

  The insulating layer 16 is formed at a height of ½ or less of the gap between the portion other than the second edge 3 b of the pixel electrode 3 and the common electrode 20 formed on the second substrate 2. In this embodiment, the insulating layer 16 is formed at a height of 1/3 to 1/2 of the gap between the portion other than the second edge 3b of the pixel electrode 3 and the common electrode 20.

Further, in this embodiment, respectively portion that enters under the insulating layer 16 of the first edge 3a of the pixel electrode 3, overlapping portion on the insulating layer 16 of the second edge 3b, the insulating layer It is formed in a width of about 1/4 of the width of 16.

  Further, on the second edge 3 b side of the pixel electrode 3, a compensation capacitance forming portion 3 c facing the vertical side portion 13 a of the capacitance electrode 13 through the overcoat insulating film 14 is provided on the insulating layer 16. It is formed in the bottom. The portion of the compensation capacitance forming portion 3c that enters under the insulating layer 16 is formed to have substantially the same width as the portion of the first edge portion 3a that enters under the insulating layer 16.

  The first edge portion 3a and the compensation capacitance forming portion 3c of the pixel electrode 3 are formed on the overcoat insulating film 14 on the first edge portion 3a side and the second insulating layer 16 before the insulating layer 16 is formed. It consists of the 1st transparent conductive film formed in the shape extended on the outer side from under the insulating layer 16 by the side of the edge 3b. Further, the portion between the first edge 3a and the compensation capacitance forming portion 3c of the pixel electrode 3 and the second edge 3b are formed on the insulating layer 16 and the first transparent conductive film after the insulating layer 16 is formed. It consists of the 2nd transparent conductive film formed on the overhang part.

  Therefore, the first edge 3a and the compensation capacitance forming part 3c are inserted under the insulating layers 16 and 16 on the first edge 3a side and the second edge 3b side, and the second edge 3b is moved to the second edge 3b. The pixel electrode 3 overlaid on the insulating layer 16 on the edge 3b side can be formed.

  The compensation capacitor Cs includes the capacitor electrode 13, the first edge 3 a of the pixel electrode 3, the edge at both ends in the column direction and the compensation capacitor forming portion 3 c, and the capacitor electrode 13 and the pixel electrode 3. And a dielectric layer made of the overcoat insulating film 14 therebetween. The same signal as the common electrode signal applied to the common electrode 20 is applied to the capacitive electrode 13.

A first alignment film 17 made of polyimide or the like is formed on the first substrate 1 so as to cover the pixel electrodes 3 and the insulating layers 16. The first alignment film 17 is rubbed from the second edge 3 b of the pixel electrode 3 in a direction 17r toward the first edge 3 a. In this embodiment, the first alignment film 17 is rubbed in a direction substantially orthogonal to the first edge 3 a and the second edge 3 b of the pixel electrode 3.

On the other hand, on the surface of the second substrate 2 facing the first substrate 1, the pixel electrodes 3 arranged in the row direction are adjacent to each other and the pixel electrodes 3 arranged in the column direction are adjacent to each other. A light shielding film 18 is formed corresponding to the above. Further, on the second substrate 2, the respectively corresponding to the columns of the pixel electrodes 3, the three color filters of red filters 19R, the green filter 19G and blue filter 19B are formed in a stripe shape .

  The common electrode 20 is made of a transparent conductive film such as an ITO film, and is formed on the color filters 19R, 19G, and 19B so as to correspond to the entire arrangement region of the pixel electrodes 3.

  A second alignment film 21 made of polyimide or the like is formed on the second substrate 2 so as to cover the common electrode 20. The second alignment film 21 is rubbed in a predetermined direction 21r with respect to the rubbing direction 17r of the first alignment film 17.

  The liquid crystal display element of this embodiment is a non-twisted homogeneous alignment type liquid crystal display element, and the second alignment film 21 is rubbed in a direction 21r opposite to the rubbing direction 17r of the first alignment film 17. ing.

  Then, the molecules 22a of the liquid crystal 22 sealed between the first substrate 1 and the second substrate 2 are rubbed in the rubbing direction 17r of the first alignment film 17 with respect to the first substrate 1 as shown in FIG. Toward the downstream side (the end end side of the rubbing) at an angle of about 5 degrees and about 5 degrees toward the downstream side of the rubbing direction 21r of the second alignment film 21 with respect to the second substrate 2. In a state of being pretilted at an angle, the alignment layers 17 and 21 are homogeneously aligned with their molecular long axes aligned in the rubbing directions 17r and 21r.

  The liquid crystal display element further includes a first polarizing plate 23 disposed on the outer surface of the first substrate 1 and a second polarizing plate 24 disposed on the outer surface of the second substrate 2. The first polarizing plate 23 is arranged with its absorption axis (not shown) oriented in the direction of about 45 degrees with respect to the rubbing directions 17r and 21r of the alignment films 17 and 21, and the second polarizing plate 24. Is arranged with its absorption axis (not shown) substantially orthogonal to the absorption axis of the first polarizing plate 23.

  The liquid crystal display element sequentially selects a row of each pixel electrode 3 (hereinafter referred to as a pixel row) in units of one row, and supplies a data signal to each pixel electrode 3 in the selected row. A driving electric field having a strength corresponding to the potential of the data signal is applied between the common electrode 20 and the common electrode 20, and the alignment state of the liquid crystal molecules 22a is changed by the driving electric field for display.

  In other words, each scanning signal line 10 is applied with a scanning signal having a waveform that has a potential for turning on the TFT 4 during the selection period of the corresponding pixel row. Further, a data signal whose potential changes in accordance with the gradation value of the image data is applied to each data signal line 11 for each selection period of each pixel row. Meanwhile, a predetermined common signal is applied to the common electrode 20. The same signal as the common signal is applied to the capacitor electrode 13 in each row.

  The data signal applied to each data signal line 11 is supplied to the pixel electrode 3 connected to the TFT 4 by turning on the TFT 4, and the data signal is transmitted between the pixel electrode 3 and the common electrode 20. A driving electric field having a strength corresponding to the potential is applied.

  The liquid crystal display element prevents the image of the driving electric field from being burned out due to a bias in the polarity of the driving electric field applied between the pixel electrode 3 and the common electrode 20 and deterioration due to electrolysis of the liquid crystal. It is driven by inverting the polarity at a predetermined cycle.

The polarity inversion driving, a so-called line inversion driving where reversing the polarity of the driving electric field for each pixel row, and so-called dot inversion driving where reversing the polarity of the driving electric field to each pixel arranged in the row direction, there is. The line inversion drive is performed by applying to the common electrode 20 a common signal having a waveform whose polarity is alternately inverted every selection period of each pixel row. In addition, the dot inversion driving is performed by applying a data signal in which the polarity is inverted for each adjacent data signal line 11, 11 to each data signal line 11.

  Since the liquid crystal display element has the above-described configuration, it is possible to perform display with good quality without generating disclination in the opening area of the pixel.

  That is, FIG. 5 is a schematic diagram of liquid crystal molecule alignment when an electric field is applied in the liquid crystal display element of the above example, and FIG. 6 is a schematic diagram of liquid crystal molecule alignment when an electric field is applied in a liquid crystal display element of a comparative example. The liquid crystal molecular alignment on the cross section along a row direction is shown.

  The liquid crystal molecule orientations shown in FIGS. 5 and 6 are respectively applied to the common electrode 20 by applying the dot inversion drive to one of the adjacent pixel electrodes 3 and 3. This is an example of orientation when a data signal of + 5V is supplied to the potential and a data signal of −5V is supplied to the other pixel electrode 3 with respect to the potential of the common signal.

  In the liquid crystal display element of the comparative example, an insulating layer 16 is provided corresponding to a portion where the pixel electrodes 30, 30 arranged in the row direction are adjacent to each other, and the pixel electrodes 30 are arranged along two vertical sides thereof. Both the first edge 3a and the second edge 3b are formed on the insulating layer 16 so as to overlap each other. Further, the liquid crystal display element includes a first alignment film formed so as to cover each pixel electrode 3 and a second alignment film (none of which is shown) formed so as to cover the common electrode 20 in the above embodiment. Are rubbed in the same directions 17r and 21r, and the liquid crystal molecules 22a are homogeneously aligned with their molecular long axes aligned in the row direction.

  In the liquid crystal display element of this comparative example, since the distance between the edge of the pixel electrode 3 and the common electrode 20 is reduced, the direction of the driving electric field due to the influence of the lateral electric field generated between the adjacent pixel electrodes 3 and 3 Can reduce distortion.

  However, in this liquid crystal display element, since the edge portions 3a and 3b of the adjacent pixel electrodes 3 and 3 are adjacent to each other on the insulating layer 16, each pixel electrode 3 is interposed between the pixel electrodes 3 and 3. , 3 generates a lateral electric field having a strength corresponding to the potential difference between the data signals supplied to each of the substrate 3 and the substrate. In the region corresponding to the vicinity of the edge of the pixel electrode 3 due to the influence of the lateral electric field, the substrate It is distorted in a direction inclined obliquely with respect to the normal direction. The directions of distortion of the drive electric field due to the lateral electric field are opposite to each other on one edge side of the pixel electrode 3 and the opposite edge side thereof.

  The lateral electric field is generated both between the pixel electrodes arranged in the row direction and between the pixel electrodes arranged in the column direction. Due to the influence of these lateral electric fields, the direction of the driving electric field is changed in the row direction. And distortion in two directions of the column direction.

  On the other hand, the disclination caused by the liquid crystal molecules 22a rising and aligning in a direction tilting in the direction opposite to the pretilt direction in the initial alignment state is generated by the distortion of the driving electric field in the direction opposite to the pretilt direction. .

  That is, in the liquid crystal display element in which the liquid crystal molecules 22a are aligned homogeneously with the molecular long axis aligned in the row direction, the disclination occurs due to distortion of the driving electric field in the row direction.

  The distortion of the driving electric field in the row direction in the liquid crystal display element of the comparative example is between the first edge 3a side and the second edge 3b side of the pixel electrode 3 as shown by the equipotential line E in FIG. This is a nearly symmetric distortion.

  The distortion direction of the driving electric field on the first edge 3a side of the pixel electrode 3 is the pretilt direction in the initial alignment state of the liquid crystal molecules 22a, and the distortion direction of the driving electric field on the second edge 3b side is the pretilt direction. The direction is the opposite direction.

  Therefore, the liquid crystal molecules 22a in the region other than the vicinity of the second edge 3b of the pixel electrode 3 rise and align in the normal tilt direction that is the same as the pretilt direction, but the liquid crystal molecules 22a in the region near the second edge 3b. However, it rises in the direction of tilting in the direction opposite to the direction of the pretilt to generate disclination.

  In particular, in the dot inversion driving, the polarity of the data signal supplied to one of the adjacent pixel electrodes 3 and 3 and the polarity of the data signal supplied to the other pixel electrode 3 are opposite to each other. A strong horizontal electric field is generated between the pixel electrodes 3 and 3 arranged in a row, the distortion of the driving electric field in the row direction is increased, and the disclination is generated in the opening region of the pixel.

  The boundary between the forward tilt alignment region in which the liquid crystal molecules 22a rise and align in the normal tilt direction, which is the same as the pretilt direction, and the disclination generation region is called a disclination line. When the liquid crystal display element of the comparative example is driven by dot inversion, a disclination line DL is formed at a position as shown in FIG.

  On the other hand, in the liquid crystal display element of the above embodiment, each pixel electrode 3 has the first edge 3a out of the edges along the two vertical sides below the insulating layer 16 on the first edge 3a side. Since the second edge portion opposite to the first edge portion is formed on the insulating layer 16 on the second edge side, the pixel electrodes 3 arranged in the row direction are inserted. 3 has little influence on the driving electric field applied between the pixel electrode 3 and the common electrode 20.

  Further, the data signal line 11 and the pixel electrode 3 are electrically shielded by the capacitor electrode 13 formed on the interlayer insulating film 12 so as to cover the portion on the data signal line 11. A horizontal electric field does not occur between the line 11 and the edge of the pixel electrode 3.

  Furthermore, the liquid crystal display element of the above embodiment has a first edge formed by entering a portion of the driving electric field applied between the pixel electrode 3 and the common electrode 20 below the insulating layer 16 of the pixel electrode 3. The intensity of the electric field in the region corresponding to the portion 3 a is reduced by the voltage drop in the insulating layer 16. On the other hand, the electric field in the region corresponding to the second edge 3b formed on the insulating layer 16 of the pixel electrode 3 is a high electric field without a voltage drop due to the insulating layer 16.

  Therefore, as indicated by the equipotential line E in FIG. 5, the driving electric field is distorted in the inner direction of the pixel electrode 3 on the first edge 3 a side (the side where the electric field strength is reduced) of the pixel electrode 3, and The second edge 3b is distorted in the outer direction of the pixel electrode 3.

  That is, with respect to the distortion of the driving electric field, the region of distortion in the direction opposite to the pretilt direction in the initial alignment state of the liquid crystal molecules 22a is shifted in the direction of the adjacent pixel electrode 3 with respect to the distortion of the driving electric field of the comparative example. Distortion.

  Disclination occurs in a region where the drive electric field is distorted in the direction opposite to the pretilt direction of the liquid crystal molecules 22a. Therefore, in the liquid crystal display element of the above embodiment, the disclination line DL is formed at a position deviated in the pixel outward direction from the liquid crystal display element of the comparative example, and the disclination line DL is formed from the center of the insulating layer 16. Is shorter than the comparative example.

  Therefore, according to the liquid crystal display element of the above embodiment, even when the potential difference between the data signals respectively supplied to the pixel electrodes 3 and 3 arranged in the row direction is large as in the case of performing dot inversion driving, Good quality display can be performed without causing disclination in the opening area.

  The driving of the liquid crystal display element is not limited to dot inversion driving but may be line inversion driving. Also in this line inversion drive, a horizontal electric field is generated between the edge portions 3a and 3b of the adjacent pixel electrodes 3 and 3 due to the potential difference between the data signals supplied to the pixel electrodes 3 and 3 arranged in the row direction. For this reason, the direction of the driving electric field applied between the pixel electrode 3 and the common electrode 20 is distorted due to the influence of the lateral electric field. It is possible to perform display with good quality without generating any.

  Further, in the above embodiment, the insulating layer 16 is formed at a height of ½ or less of the gap between the portion other than the second edge 3 b of the pixel electrode 3 and the common electrode 20. A sufficient gap between the insulating layer 16 and the second substrate 2 can be secured, and the liquid crystal 22 can be injected into the gap between the first substrate 1 and the second substrate 2 in a short time.

[Second Example]
In the liquid crystal display element of the second embodiment shown in FIGS. 7 and 8, the portion of the second edge 3 b of the pixel electrode 3 that overlaps the insulating layer 16 is located more than the center in the width direction of the insulating layer 16. The width is formed so as to project to the adjacent pixel electrode 3 side, and the other configuration is the same as in the first embodiment.

  In this embodiment, the second edge 3b of the pixel electrode 3 is formed such that its edge is close to the position on the edge of the first edge 3a of the adjacent pixel electrode 3. However, the second edge 3b may be formed to have an arbitrary width as long as it does not overlap with the portion on the adjacent pixel electrode 3.

  FIG. 9 is a schematic diagram of liquid crystal molecule alignment when an electric field is applied in the liquid crystal display element of the second embodiment, and shows the liquid crystal molecule alignment on a cross section along the row direction. The liquid crystal molecule orientation shown in FIG. 9 is applied to the potential of the common signal applied to the common electrode 20 to one of the adjacent pixel electrodes 3 and 3 by the dot inversion driving. This is an example of alignment when a data signal of +5 V is supplied and a data signal of −5 V is supplied to the other pixel electrode 3 with respect to the potential of the common signal.

Since the liquid crystal display element of the second embodiment is configured as described above, the position where the disclination line DL is formed can be biased further toward the outside of the pixel than in the first embodiment. it can. Therefore, the width of the light shielding film 19 formed on the second substrate 2 can be reduced and the aperture ratio can be improved.

[Third embodiment]
In the liquid crystal display element of the third embodiment shown in FIGS. 10 and 11, the insulating layer 16 is smaller than the gap between the common electrode 20 and the portion other than the second edge 3b of the pixel electrode 3, 1/2 of the gap is obtained by forming the super El height, other configurations are the same as those of the first embodiment.

  In this embodiment, the insulating layer 16 is formed at a height of about 3/4 of the gap between the common electrode 20 and the portion other than the second edge 3 b of the pixel electrode 3. The second edge 3b overlaid on the insulating layer 16 of the pixel electrode 3 is formed to have substantially the same width as that of the first embodiment.

  FIG. 12 is a schematic diagram of liquid crystal molecule alignment when an electric field is applied in the liquid crystal display element of the third embodiment, and shows the liquid crystal molecule alignment on a cross section along the row direction. Note that the liquid crystal molecular orientation shown in FIG. 12 is applied to one of the adjacent pixel electrodes 3 and 3 with respect to the potential of the common signal applied to the common electrode 20 by the dot inversion driving. This is an example of alignment when a data signal of +5 V is supplied and a data signal of −5 V is supplied to the other pixel electrode 3 with respect to the potential of the common signal.

Since the liquid crystal display element of the third embodiment is configured as described above, the position where the disclination line DL is formed can be biased further toward the outside of the pixel than in the first embodiment. it can. Therefore, the width of the light shielding film 19 formed on the second substrate 2 can be reduced and the aperture ratio can be improved.

[Fourth embodiment]
In the fourth embodiment shown in FIG. 13, the insulating layer 16 is formed at the same height as the third embodiment, and the portion of the second edge 3 b of the pixel electrode 3 that overlaps the insulating layer 16 is formed. Similar to the second embodiment, the insulating layer 16 is formed to have a width projecting toward the pixel electrode 3 adjacent to the central portion in the width direction, and the other configuration is the same as the first embodiment. . According to the fourth embodiment , a synergistic effect between the second embodiment and the third embodiment can be obtained.

[Fifth Example]
In the fifth embodiment shown in FIG. 14, a portion other than the second edge 3b of the pixel electrode 3 is formed by a first transparent conductive film formed before the insulating layer 16 is formed, and the second edge is formed. The second transparent portion formed by overlapping the portion 3b on the insulating layer 16 on the second edge 3b side and the second edge 3b side portion of the first transparent conductive film after the insulating layer 16 is formed. It is formed by a conductive film.

  According to this embodiment, the first edge portion 3a and the compensation capacitance forming portion 3c are inserted under the insulating layers 16 and 16 on the first edge portion 3a side and the second edge portion 3b side, and the second edge portion 3b is The pixel electrode 3 overlaid on the insulating layer 16 on the second edge 3b side can be formed.

[Sixth embodiment]
In each of the above embodiments, the compensation capacitor forming portion 3c facing the capacitor electrode 13 through the overcoat insulating film 14 is inserted under the insulating layer 16 on the second edge 3b side of the pixel electrode 3. Although formed, the compensation capacitance forming portion 3c may be omitted.

In the sixth embodiment shown in FIG. 15, the compensation capacitance forming portion 3 c is omitted, and the portion of the compensation capacitance Cs on the second edge 3 b side of the pixel electrode 3 is used as the second edge of the pixel electrode 3. 3b and is obtained by forming a vertical side portion 13a of the capacitor electrode 13, a dielectric layer composed of the overcoat insulating film 14 and the insulating layer 16. by.

[Other embodiments]
In each of the above embodiments, the first alignment film 17 formed so as to cover each pixel electrode 3 is rubbed in a direction substantially orthogonal to the first edge 3 a and the second edge 3 b of the pixel electrode 3. However, the rubbing direction 17r of the first alignment film 17 may be a direction that obliquely intersects the first edge 3a and the second edge 3b of the pixel electrode 3.

  The present invention can be applied not only to non-twisted homogeneous alignment type liquid crystal display elements but also to, for example, TN type liquid crystal display elements.

Further, in each of the above embodiments, the insulating layer 16 is provided so as to correspond to the portions where the pixel electrodes 3 and 3 arranged in the row direction intersecting the data signal line 11 are adjacent to each other. Are provided in correspondence with portions where the pixel electrodes 3 and 3 arranged in the column direction intersecting the scanning signal line 10 are adjacent to each other, and each pixel electrode 3 has a first edge on a predetermined side. The second edge portion opposite to the first edge portion is formed so as to overlap the insulating layer 16 on the second edge side. The alignment film 17 may be rubbed in a direction from the second edge toward the first edge.

  According to the liquid crystal display element of this configuration, in line inversion driving in which the polarity of the driving electric field is inverted for each pixel row, it is possible to perform display with good quality without generating disclination in the opening area of the pixel. it can.

DESCRIPTION OF SYMBOLS 1 ... 1st board | substrate, 2 ... 2nd board | substrate, 3 ... Pixel electrode, 3a ... 1st edge part, 3b ... 2nd edge part, 3c ... Compensation capacity | capacitance formation part, 14 ... TFT, 10 ... Scanning signal line, 11 ... Data signal line, 12 ... interlayer insulating film, 13 ... capacitive electrode, 13a ... vertical side of capacitive electrode, Cs ... compensation capacitance, 14 ... overcoat insulating film, 15 ... contact hole, 16 ... insulating layer, 17 ... first Alignment film, 17r ... rubbing direction, 20 ... common electrode, 21 ... second alignment film, 21r ... rubbing direction, 22 ... liquid crystal, 22a ... liquid crystal molecule, DL ... disclination line

Claims (11)

A first substrate formed by arranging a plurality of pixel electrodes to which a data signal is supplied via a thin film transistor;
A second substrate on which a common electrode facing each pixel electrode is formed;
A liquid crystal sealed between the first substrate and the second substrate,
Composed of
In a liquid crystal display element that displays by changing the alignment state of liquid crystal molecules by applying a voltage between the pixel electrode and the common electrode,
On the first substrate, an insulating layer that protrudes toward the second substrate from the formation surface of each pixel electrode is provided so as to correspond to the portions where the pixel electrodes are adjacent to each other,
Wherein each pixel electrode, respectively, a first edge of the predetermined side allowed to enter under the insulating layer of those said one edge side, the person said second edge portion opposite to the first edge Formed over the insulating layer on the second edge side,
Wherein the first orientation of the second alignment film covering the common electrode and the prior SL first substrate and the first alignment film covering the pixel electrode and the insulating layer on the second substrate A film is rubbed in a direction from the second edge of the pixel electrode toward the first edge;
A compensation capacitor forming part is formed under the insulating layer on the second edge side of the pixel electrode,
The first edge portion and the compensation capacitance forming portion of the pixel electrode are formed in a shape projecting from below the insulating layer on the first edge side and the insulating layer on the second edge side. A first transparent conductive film, and a portion between the first edge and the compensation capacitance forming portion and the second edge are formed on the overhanging portion of the first transparent conductive film and the insulating layer. Having a second transparent conductive film formed to overlap,
The liquid crystal display element characterized by the above-mentioned. The partial overlapping on the insulating layer of the second edge of the pixel electrode, according to claim 1, characterized in that it is formed to a width projecting in the pixel electrode side adjacent the center portion of the insulating layer A liquid crystal display element according to 1. On the first substrate, the thin film transistors are formed corresponding to the formation positions of the pixel electrodes, and scanning signal lines and data signal lines connected to the thin film transistors are provided.
On the interlayer insulating film formed thereon, a capacitor electrode for forming a compensation capacitor is provided between each pixel electrode,
On the overcoat insulating film formed to cover the capacitor electrode, the insulating layer and each pixel electrode are formed,
3. The pixel electrode according to claim 1, wherein each of the pixel electrodes is connected to the thin film transistor corresponding to the pixel electrode in a contact hole provided in the overcoat insulating film and the interlayer insulating film. Liquid crystal display element.   4. The liquid crystal display element according to claim 3, wherein the insulating layer is provided in a portion where pixel electrodes arranged in a direction crossing the data signal line are adjacent to each other.   5. The liquid crystal display element according to claim 4, wherein the capacitor electrode is formed so as to cover a portion on the data signal line, and the insulating layer is formed on a portion on the capacitor electrode.   5. The liquid crystal display element according to claim 4, wherein the insulating layer is provided in a portion where pixel electrodes arranged in a direction intersecting the scanning signal line are adjacent to each other. 6. The second edge side of the pixel electrode, and wherein the compensation capacitor forming part facing the capacitor electrode via the overcoat insulating film is formed by entering under the insulating layer The liquid crystal display element according to claim 3 . The second edge than in the portion of the pixel electrode has the first transparent conductive film, said second edge, before Symbol second edge side of the insulating layer and the first transparent conductive the liquid crystal display device according to claim 7, characterized in that it has the second transparent conductive film, wherein the stacked formed in a portion of the second edge side of the membrane. The second alignment film is rubbed in a direction opposite to the rubbing direction of the first alignment film, and the liquid crystal is composed of nematic liquid crystal having positive dielectric anisotropy, and the liquid crystal molecules of the nematic liquid crystal are the liquid crystal display device according to any of claims 1 to 8, characterized in that aligning the molecular long axis in the rubbing direction of the first alignment film and the second alignment layer are homogeneously aligned. The insulating layer of claims 1 to 9, characterized in that it is formed in 1/2 or less of the height of the gap between the common electrode and the second edge than in the portion of the pixel electrode Any one of the liquid crystal display elements. The insulating layer is formed to have a height smaller than a gap between the portion other than the second edge of the pixel electrode and the common electrode and more than 1/2 of the gap. the liquid crystal display device according to any of claims 1 to 9.

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