JP2006184336A - Liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vertical aligned type active matrix liquid crystal display element, where liquid crystal molecules in respective pixels are stably aligned in the falling orientation by application of voltage and an image having satisfactory quality can be displayed. <P>SOLUTION: A plurality of pixel electrodes 3 are provided, by superposing one end edges thereof on side edge parts of a gate wiring 10 adjacent to the pixel electrodes 3, a first vertical alignment layer on an inner surface of a rear substrate, on which the plurality of pixel electrodes are provided, is subjected to rubbing treatment in a direction 1a from an end edge side opposite to the side adjacent to the gate wiring 10 of each pixel electrode 3 to acounter edge side and a second vertical alignment layer on an inner surface of a front substrate, on which a counter electrode is provided is subjected to rubbing treatment in a direction 2b that is reverse to the rubbing direction 1a of the first vertical alignment layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vertical alignment type active matrix liquid crystal display element using a thin film transistor (hereinafter referred to as TFT) as an active element.

A vertical alignment type active matrix liquid crystal display element is provided on the inner surface of one of a pair of substrates facing each other with a predetermined gap and the inner surfaces facing each other of the pair of substrates, A plurality of pixel electrodes arranged in a matrix in the column direction, a plurality of TFTs provided on the inner surface of the one substrate in correspondence with one end edges of the plurality of pixel electrodes, and connected to the corresponding pixel electrodes, respectively A plurality of gates provided on the inner surface of the one substrate along one side of each pixel electrode row and one side of each pixel electrode column, and supplying gate signals and data signals to the TFTs in the rows and columns, respectively. Wiring and data wiring, provided on the inner surface of the other substrate, forming a plurality of pixels by regions facing each of the plurality of pixel electrodes, and on the inner surfaces of the pair of substrates Each of the first and second vertical alignment films provided so as to cover the electrodes, and a liquid crystal layer having negative dielectric anisotropy sealed in a gap between the pair of substrates (patent) Reference 1).
Japanese Patent No. 2565639

  In a vertical alignment type liquid crystal display element, liquid crystal molecules are tilted from a vertical alignment state by applying a write voltage between the electrodes for each of a plurality of pixels composed of regions where a plurality of pixel electrodes and a counter electrode face each other. To display the image.

  However, in the conventional vertical alignment type liquid crystal display element, the tilted alignment of liquid crystal molecules due to the application of the write voltage of each pixel is unstable, and a good quality display cannot be obtained.

  In addition, for liquid crystal display elements, it is desired to form a plurality of pixel electrodes in an elongated shape and increase the pixel density for high definition, but conventional vertical alignment type liquid crystal display elements are pixel electrodes. Is formed in an elongated shape, the tilted orientation of the liquid crystal molecules due to the application of the write voltage of each pixel becomes more unstable, and the display quality further deteriorates.

  An object of the present invention is to provide a vertical alignment type active matrix liquid crystal display element capable of displaying a good quality image by stably tilting and aligning liquid crystal molecules of each pixel by applying a writing voltage. It is.

  The liquid crystal display element of the present invention is provided on the inner surface of one of the pair of substrates facing each other with a predetermined gap and the inner surfaces facing each other of the pair of substrates in the row direction and the column direction. A plurality of pixel electrodes arranged in a matrix, a plurality of TFTs provided on the inner surface of the one substrate in correspondence with one end edges of the plurality of pixel electrodes, and connected to the corresponding pixel electrodes, respectively, A plurality of gate wirings and data provided on the inner surface of the substrate along one side of each pixel electrode row and one side of each pixel electrode column and supplying gate signals and data signals to the TFTs in the rows and columns, respectively. A wiring, a counter electrode provided on an inner surface of the other substrate and forming a plurality of pixels by regions facing the plurality of pixel electrodes, and an inner surface of the pair of substrates covering the electrodes Each of the plurality of pixel electrodes includes one end edge of the first and second vertical alignment films and a liquid crystal layer having negative dielectric anisotropy sealed in a gap between the pair of substrates. On the side edge adjacent to the pixel electrode of the gate wiring, and the first vertical alignment film on the inner surface of the one substrate on which the plurality of pixel electrodes are provided is the gate of the pixel electrode. The second vertical alignment film on the inner surface of the other substrate on which the counter electrode is provided is rubbed in a direction from the edge opposite to the side adjacent to the wiring toward the edge adjacent to the gate wiring. The first vertical alignment film is rubbed in a direction opposite to the rubbing direction.

  In this liquid crystal display element, the plurality of pixel electrodes are preferably formed in an elongated shape for high definition of the liquid crystal display element. In this case, one end edge in the longitudinal direction of the pixel electrode is formed on the gate wiring. What is necessary is just to provide it by overlapping on a side edge part.

  In the liquid crystal display element of the present invention, each of the plurality of pixel electrodes is provided such that one end edge thereof is overlapped with a side edge adjacent to the pixel electrode of the gate wiring, and the one substrate on which the plurality of pixel electrodes are provided is provided. The counter electrode is provided by rubbing the first vertical alignment film on the inner surface in a direction from the edge of the pixel electrode opposite to the side adjacent to the gate wiring to the edge adjacent to the gate wiring. Since the second vertical alignment film on the inner surface of the other substrate is rubbed in the direction opposite to the rubbing direction of the first vertical alignment film, the liquid crystal molecules of each pixel are connected to the pixel electrode. By applying a write voltage to the counter electrode, a portion corresponding to the gate line is attracted to a tilt alignment direction of liquid crystal molecules due to an electric field between the gate line and the counter electrode, and a rubbing direction of the vertical alignment film Stipulated by Oriented fallen in the direction.

  Therefore, according to this liquid crystal display element, the liquid crystal molecules of each pixel can be stably tilted and oriented by applying the write voltage, and a good quality image can be displayed.

  In this liquid crystal display element, the plurality of pixel electrodes are preferably formed in an elongated shape for high definition of the liquid crystal display element. In this case, one end edge in the longitudinal direction of the pixel electrode is formed on the gate wiring. By overlapping the side edge portions, the liquid crystal molecules of each pixel can be stably tilted and oriented by applying the write voltage, and a good quality image can be displayed.

  1 to 5 show one embodiment of the present invention, FIG. 1 is a plan view of a part of one substrate of a liquid crystal display element, and FIGS. 2 and 3 are II-II and III-III lines in FIG. It is sectional drawing of the liquid crystal display element which follows a line.

  This liquid crystal display element is a vertical alignment type active matrix liquid crystal display element using TFT as an active element. As shown in FIGS. 1 to 3, a pair of transparent substrates 1 facing each other with a predetermined gap therebetween. , 2 and the inner surfaces of these substrates 1 and 2 facing each other, for example, on the inner surface of one substrate, for example, the substrate 1 on the opposite side of the display viewing side (hereinafter referred to as a rear substrate), A plurality of transparent pixel electrodes 3 arranged in a matrix in the column direction, and provided on the inner surface of the rear substrate 1 so as to correspond to one end edges of the plurality of pixel electrodes 3, and connected to the corresponding pixel electrodes 3, respectively. A plurality of TFTs 4 are provided on the inner surface of the rear substrate 1 along one side of each pixel electrode row and one side of each pixel electrode column, and supply gate signals and data signals to the TFTs 4 in the rows and columns. Duplicate A plurality of pixels are formed by the gate wiring 10 and the data wiring 11 and the inner surface of the other substrate, that is, the substrate on the observation side (hereinafter referred to as the front substrate) 2 and facing the plurality of pixel electrodes 3, respectively. A single film-like transparent counter electrode 15, first and second vertical alignment films 14, 18 provided on the inner surfaces of the pair of substrates 1, 2, and the pair of substrates 1, 2, respectively. The liquid crystal layer 19 has negative dielectric anisotropy enclosed in a gap.

  The plurality of TFTs 4 include a gate electrode 5 formed on the substrate surface of the rear substrate 1, a transparent gate insulating film 6 that covers the gate electrode 5 and is formed in the entire array region of the pixel electrode 3, An i-type semiconductor film 7 formed on the gate insulating film 6 so as to face the gate electrode 5, and an n-type semiconductor film (not shown) on one side and the other side of the i-type semiconductor film 7. A drain electrode 8 and a source electrode 9 are formed.

  The gate wiring 10 is formed integrally with the gate electrode 5 of the TFT 4 on the substrate surface of the rear substrate 1, and the data wiring 11 is formed on the gate insulating film 6 and on the drain electrode 8 of the TFT 4. And is integrally formed.

  The plurality of pixel electrodes 3 are provided on the gate insulating film 6 so that one end edge thereof is overlapped with a side edge portion adjacent to the pixel electrode 3 of the gate wiring 10. The electrode 9 is connected to one side of the edge of the pixel electrode 3 corresponding to the TFT 4.

  In this embodiment, in order to increase the pixel density and increase the definition of the liquid crystal display element, the plurality of pixel electrodes 3 are elongated so that the width along the gate wiring 10 is narrower than the normal pixel electrode width. The one end edge in the longitudinal direction is provided so as to overlap the side edge portion of the gate wiring 10.

  Further, a compensation capacitor electrode is formed on the substrate surface of the rear substrate 1 so as to correspond to the pixel electrode 3 in each row and to form a compensation capacitor having the gate insulating film 6 as a dielectric layer between the pixel electrode 3 and the substrate electrode. 13 is provided.

  In this embodiment, the compensation capacitor electrode 13 is provided so as to correspond to the edge of the pixel electrode 3 of each row on the side opposite to the TFT adjacent side. However, the compensation capacitor electrode 13 corresponds to the pixel electrode 3. You may provide corresponding to the edge part on the opposite side to a TFT adjacent side, and a both-sides edge part.

  The compensation capacitor electrodes 13 respectively corresponding to the pixel electrodes 3 in each row are capacitor electrode connection wires (not shown) provided in parallel with the data wires 12 at one end or both ends outside the array region of the plurality of pixel electrodes 3. Commonly connected to

  Further, an overcoat insulating film 12 is provided on the inner surface of the rear substrate 1 so as to cover the plurality of TFTs 4 and the data lines 11 except for portions corresponding to the plurality of pixel electrodes 3. A first vertical alignment film 14 is formed so as to cover the plurality of pixel electrodes 3.

  On the other hand, on the inner surface of the front substrate 2, a black mask 16 in the form of a lattice film facing regions between a plurality of pixels respectively corresponding to the plurality of pixel electrodes 3 provided on the inner surface of the rear substrate 1, and Red, green, and blue color filters 17R, 17G, and 17B corresponding to a plurality of pixels are provided, and the counter electrode 15 is formed on the color filters 17R, 17G, and 17B. In addition, a second vertical alignment film 18 is formed.

  The first vertical alignment film 14 on the inner surface of the rear substrate 1 is directed from the edge of the pixel electrode 3 opposite to the side adjacent to the gate wiring 10 to the edge adjacent to the gate wiring 10. The second vertical alignment film 18 on the inner surface of the front substrate 2 is rubbed in the direction opposite to the rubbing direction of the first vertical alignment film 14. 1 and 2, the arrow 1 a indicates the rubbing direction of the first vertical alignment film 14 of the rear substrate 1, and the arrow 2 a indicates the rubbing direction of the second vertical alignment film 18 of the front substrate 2.

  The rear substrate 1 and the front substrate 2 are bonded together via a frame-shaped sealing material (not shown) that surrounds the array region of the plurality of pixel electrodes 3.

  Further, although not shown, the rear substrate 1 has a protruding portion protruding outward from the front substrate 2 at one end in the row direction and one end in the column direction. A plurality of gate-side driver connection terminals are formed in an array at a portion, and a plurality of data-side driver connection terminals are formed at an extension in the column direction.

  The plurality of gate wirings 10 are led out to the row extending portions and connected to the plurality of gate side driver connection terminals, respectively, and the plurality of data wirings 11 are connected to the column extending portions. A capacitor electrode connection wiring (not shown) that is derived and connected to each of the plurality of data-side driver connection terminals and to which the compensation capacitor electrodes 13 corresponding to the pixel electrodes 3 in each row are connected in common is provided in the row direction and the column. It is led out to one or both of the protruding portions in the direction, and is connected to a reference potential terminal among a plurality of driver connection terminals of the protruding portion.

  The liquid crystal layer 19 is enclosed in a region surrounded by the sealing material between the rear substrate 1 and the front substrate 2, and the liquid crystal molecules 19 a of the liquid crystal layer 19 are formed on the inner surfaces of both substrates 1 and 2. Due to the vertical alignment properties of the vertical alignment films 14 and 18 provided respectively on the first and second substrates, the vertical alignment films 14 and 18 are aligned substantially perpendicularly to the surfaces of the substrates 1 and 2 while being slightly tilted in the rubbing direction of the vertical alignment films 14 and 18. Yes.

  Further, polarizing plates 20 and 21 are respectively disposed on the outer surfaces of the rear substrate 1 and the front substrate 2 with their transmission axes directed in a predetermined direction. In this embodiment, the polarizing plates 20 and 21 are arranged so that their transmission axes are substantially perpendicular to each other so that the liquid crystal display element performs display in a normally black mode.

  This liquid crystal display element displays an image by aligning the liquid crystal molecules 19a from the vertical alignment state by applying a write voltage between the pixel electrode 3 and the counter electrode 15 for each of a plurality of pixels, The liquid crystal molecules 19a are aligned substantially vertically in the inter-pixel region where the write voltage is not applied, and are tilted and aligned for each pixel according to the voltage value of the write voltage.

  In this liquid crystal display element, a plurality of pixel electrodes 3 are provided so that one end edge thereof is overlapped with a side edge adjacent to the pixel electrode 3 of the gate wiring 10, and the substrate 1 is provided after the plurality of pixel electrodes 3 are provided. The first vertical alignment film 14 on the inner surface is rubbed in the direction from the edge of the pixel electrode 3 opposite to the side adjacent to the gate wiring 10 toward the edge adjacent to the gate wiring 10, Since the second vertical alignment film 18 on the inner surface of the front substrate 2 provided with 15 is rubbed in a direction opposite to the rubbing direction of the first vertical alignment film 14, the liquid crystal molecules 19a of each pixel are By applying a write voltage between the pixel electrode 3 and the counter electrode 15, the direction of the tilt alignment of the liquid crystal molecules 19 a due to the electric field between the gate line 10 and the counter electrode 15 in a portion corresponding to the gate line 10. Attracted to before Oriented collapsed direction defined rubbing direction 1a of the vertical alignment film 14 and 19, by 2a.

  4 and 5 are a plan view and a cross-sectional view schematically showing a liquid crystal molecular alignment state when a write voltage is applied to one pixel of the liquid crystal display element of the above embodiment, and FIGS. 6 and 7 show the pixel electrode 3. FIG. 6 is a plan view and a cross-sectional view schematically showing a liquid crystal molecule alignment state when a write voltage is applied to one pixel of a comparison element provided apart from the gate wiring.

  First, the tilted alignment state of the liquid crystal molecules 19a by the application of the write voltage of the comparison element will be described. In this comparison element, as shown in FIGS. 6 and 7, the liquid crystal molecules 19a of each pixel are applied by the application of the write voltage. After the pixel electrode 3 is provided from the peripheral edge of the pixel, the first vertical alignment film 14 of the substrate is aligned so as to fall in the rubbing direction 1a, but the liquid crystal molecules 19a on the end side adjacent to the gate wiring 10 of the pixel are arranged. Receives a strong lateral electric field corresponding to a gate signal generated between the gate wiring 10 and the edge of the pixel electrode 3, and the direction of the lateral electric field, that is, the rubbing direction 1a of the first vertical alignment film 14 Are oriented so as to fall in the opposite direction.

  Therefore, this comparison element is unstable in the tilted orientation of the liquid crystal molecules 19a due to the application of the write voltage of each pixel, and cannot display a good quality display. In particular, in order to increase the definition of the liquid crystal display element, the pixel electrode When 3 is formed in an elongated shape, the tilted orientation of the liquid crystal molecules 19a due to the application of the write voltage to each pixel becomes more unstable, and the display quality further deteriorates.

  On the other hand, in the liquid crystal display element of the above embodiment, the one end edge of the pixel electrode 3 is overlapped with the side edge portion adjacent to the pixel electrode 3 of the gate line 10, so that the edge of the gate line 10 and the pixel electrode 3 is overlapped. The horizontal electric field does not occur between the two.

  On the other hand, the liquid crystal molecules 19a corresponding to the gate wiring 10 are aligned so as to be tilted by a strong electric field of about −15 V corresponding to the gate signal generated between the gate wiring 10 and the counter electrode 15.

  Further, in the liquid crystal display element of the above embodiment, the first vertical alignment film 14 on the inner surface of the substrate 1 after the pixel electrode 3 is provided is opposite to the side of the pixel electrode 3 adjacent to the gate wiring 10. Since the rubbing process is performed in the direction from the edge toward the edge adjacent to the gate wiring 10, the liquid crystal molecules 19 a due to the electric field generated between the gate wiring 10 and the counter electrode 15 corresponding to the gate wiring 10. The tilt direction of the liquid crystal molecules 19a coincides with the tilt direction of the liquid crystal molecules 19a at the edge overlapping the gate wiring on the pixel electrode 3.

  Therefore, as shown in FIGS. 4 and 5, the liquid crystal molecules 19 a of the pixel are liquid crystal molecules 19 a due to an electric field between the gate wiring 10 and the counter electrode 15 in a portion corresponding to the gate wiring 10 by applying a write voltage. The tilted orientation direction of the first vertical alignment film 14 is induced to fall in the rubbing direction 1a over the entire area of the pixel.

  Therefore, according to this liquid crystal display element, the liquid crystal molecules 19a of each pixel can be stably tilted and oriented by applying the write voltage, and an image of good quality can be displayed.

  In the liquid crystal display element of the above embodiment, a plurality of pixel electrodes 3 are formed in an elongated shape for high definition of the liquid crystal display element. One end edge in the longitudinal direction of the pixel electrode 3 is connected to a gate wiring. The first vertical alignment film 14 on the inner surface of the substrate 1 is provided along the longitudinal direction of the pixel electrode 3 so as to overlap the side edge portion of the pixel electrode 3 and the plurality of pixel electrodes 3 are provided. A rubbing process is performed in the direction from the edge opposite to the side adjacent to the gate wiring 10 toward the edge adjacent to the gate wiring 10, and the second vertical surface of the inner surface of the front substrate 2 provided with the counter electrode 15 is provided. Since the alignment film 18 is rubbed in the direction opposite to the rubbing direction of the first vertical alignment film 14, even if the pixel electrode 3 is elongated, the liquid crystal molecules of each pixel are applied with the write voltage. To stably tilt and display images of good quality Rukoto can.

The top view of a part of one board | substrate of the liquid crystal display element which shows one Example of this invention. Sectional drawing of the liquid crystal display element which follows the II-II line | wire of FIG. Sectional drawing of the liquid crystal display element which follows the III-III line | wire of FIG. The top view which shows typically the liquid crystal molecule orientation state at the time of the write-in voltage application of one pixel of the said liquid crystal display element. FIG. 3 is a cross-sectional view schematically showing a liquid crystal molecule alignment state when a write voltage is applied to one pixel of the liquid crystal display element. The top view which shows typically the liquid crystal molecule orientation state at the time of the write-in voltage application of one pixel of the comparison element provided with the pixel electrode spaced apart from the gate wiring. FIG. FIG. 3 is a cross-sectional view schematically showing a liquid crystal molecule alignment state when a write voltage is applied to one pixel of the comparison element.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 2 ... Substrate, 3 ... Pixel electrode, 4 ... TFT, 10 ... Gate wiring, 11 ... Data wiring, 13 ... Compensation capacity electrode, 14 ... Vertical alignment film, 15 ... Counter electrode, 16 ... Black mask, 17R, 17G , 17B ... color filter, 18 ... vertical alignment film, 19 ... liquid crystal layer, 19a ... liquid crystal molecule, 20, 21 ... polarizing plate.

Claims (2)

A plurality of pixels provided on the inner surface of one of the pair of substrates facing each other with a predetermined gap and the inner surfaces of the pair of substrates facing each other, arranged in a matrix in the row and column directions An electrode, a plurality of thin film transistors provided on the inner surface of the one substrate so as to correspond to one end edges of the plurality of pixel electrodes, and respectively connected to the corresponding pixel electrode, and each pixel electrode on the inner surface of the one substrate A plurality of gate wirings and data wirings that are provided along one side of the row and one side of each pixel electrode column and supply gate signals and data signals to the thin film transistors in the rows and columns, and an inner surface of the other substrate A counter electrode that forms a plurality of pixels by regions facing the pixel electrodes, and an inner surface of the pair of substrates that covers the electrodes. Consists of a liquid crystal layer having first and the second vertical alignment film, a negative dielectric anisotropy is sealed in a gap between the pair of substrates,
Each of the plurality of pixel electrodes is provided with one end edge thereof overlapped with a side edge portion adjacent to the pixel electrode of the gate wiring,
The first vertical alignment film on the inner surface of the one substrate on which the plurality of pixel electrodes are provided has an edge adjacent to the gate wiring from an edge opposite to the side adjacent to the gate wiring of the pixel electrode. The second vertical alignment film on the inner surface of the other substrate provided with the counter electrode is rubbed in a direction toward the edge, and is rubbed in a direction opposite to the rubbing direction of the first vertical alignment film. A liquid crystal display element characterized by comprising:   The liquid crystal display element according to claim 1, wherein the plurality of pixel electrodes are formed in an elongated shape, and one end edge in the longitudinal direction thereof is provided so as to overlap a side edge portion of the gate wiring.

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