JP2008009273A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display wherein generation of an afterimage during image switching is prevented while a manufacturing cost is suppressed. <P>SOLUTION: In the liquid crystal display which is constituted of an array substrate, a color filter substrate and a liquid crystal layer packed between the substrates and wherein one pixel is divided into a plurality of sub pixels, a contact hole for electrically connecting a source electrode provided on a thin film transistor for driving the pixel and an ITO transparent electrode for applying voltage to the liquid crystal layer is provided in the vicinity of a step difference part in a transmission region and at a connection part connecting the sub pixels to each other. <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 used for a screen of a mobile phone, a display device of a computer, or the like.

  Small TFT-LCD (Thin Film Transistor-Liquid Crystal Display) has been widely used in recent years including cellular phones. Such devices can be used not only indoors but also outdoors, and with a digital terrestrial reception environment, etc. so that movies can be displayed with a wide viewing angle and can be viewed in direct sunlight. There is a need for a display that can be used.

  In response to such demands, transflective vertical alignment liquid crystal display devices are becoming popular. A typical structure is shown in FIGS. FIG. 1 shows a conventional example in which a transparent resin layer is provided on the color filter substrate side to reduce the cell thickness of the reflective display region. In general, a liquid crystal display device is provided with an array substrate in which unit pixels are arranged in a matrix, a color filter substrate that is provided opposite to the array substrate and displays a hue, and is filled between these two substrates. Liquid crystal layer. The array substrate and the color filter substrate are bonded together by a seal line at an edge thereof to form a predetermined cell gap (cell thickness). The cell gap between these two substrates is uniformly maintained by spacers or rivets, and is filled with a liquid crystal layer. Spacers can be classified into spherical spacers and columnar spacers according to their shapes. The spherical spacer has a fine spherical shape and is formed on the upper color filter substrate or the lower array substrate by a spraying method, and the columnar spacer is formed of a photosensitive organic film by a photo process.

  In FIG. 1, reference numeral 200 denotes an array substrate, and 201 denotes a color filter substrate. In the array substrate 200, a gate electrode 105 (gate line) is formed on a first substrate 100 made of a transparent insulating material. Although a plurality of gate electrodes 105 are actually provided in parallel, only one of them is shown in FIG. A gate insulating layer 101 for insulating the gate electrode 105 is formed on the first substrate 100 on which the gate electrode 105 is formed. The gate insulating layer 101 substantially crosses the gate electrode. Data electrodes (not shown) are formed. A plurality of data electrodes are also provided in parallel, and the gate electrode and the data electrode intersect with each other to define each pixel region. Further, a photoacryl layer 102 is formed on the gate insulating layer 101 on which the data electrode is formed as a protective layer for insulating the data electrode and flattening a predetermined step. A reflective electrode 103 is formed in a region corresponding to the reflective region on the photoacryl layer 102. An ITO (Indium Tin Oxide) transparent electrode 108 is provided on the photoacrylic layer 102 in the transmissive region and the reflective electrode 103 in the reflective region. Further, an alignment film (not shown) is applied on the ITO transparent electrode 108. In the array substrate 200, a thin film transistor Tr is formed as a switching element in a region where the gate electrode 105 and the data electrode intersect. The thin film transistor Tr is composed of a gate electrode 105 provided at the lowest level, and a drain electrode 106 and a source electrode 107 provided above the gate electrode 105 via a gate insulating film 101 and spaced apart from each other. In the present specification, the electrode connected to the data line is called a drain electrode, and the electrode connected to the ITO transparent electrode and the reflective electrode is called a source electrode. Further, a contact hole 122 is formed through the photoacrylic layer 102. The contact hole 122 is for connecting the source electrode 107 to the reflective electrode 103 and the ITO transparent electrode 108.

  Meanwhile, the color filter substrate 201 includes a color filter layer 111 including a second substrate 110 made of a transparent insulating material, a black matrix formed on the second substrate 110, and a sub color filter layer separated by the black matrix. Is provided. Further, as shown in FIG. 1, a hole 114 from which a color layer is removed is formed in a part of the color filter layer 111, and the first overcoat layer (transparent resin) is formed in the hole 114 from which the color layer has been removed. Layer) 115 is buried. Further, a second overcoat layer (transparent resin layer) 112 for forming a step in the color filter layer 111 is formed on the color filter layer 111 and the first overcoat layer 115. In addition, after the color filter layer 111, the hole 114 from which the color layer has been removed, the first overcoat layer 115, and the second overcoat layer 112 are formed, they are paired with the pixel electrodes formed on the array substrate 200. A common electrode (not shown) for applying an electric field to the liquid crystal layer is formed, and columnar spacers 104 and rivets 113 are formed thereon. Further, an alignment film (not shown) is applied thereon.

  In the conventional example of FIG. 1, it is necessary to form a thick resin composed of the first overcoat layer 115 and the second overcoat layer 112 on the color filter substrate 201 side. When these overcoat layers 115 and 112 are formed, they may be applied at once using the same material, but in that case, they cannot be planarized. In order to obtain a flattened overcoat layer, it is necessary to form each of the layers 115 and 112 separately. Therefore, in the configuration of FIG. 1, the process for forming the overcoat layer requires two times. Become. For this reason, there is a problem that it leads to cost increase.

  From this point of view, FIG. 2 eliminates the second overcoat layer 112 on the color filter substrate 201 side shown in FIG. 1 and provides a photoacrylic layer 120, which is a transparent resin layer, on the array substrate 200 side. As shown in FIG. 2, the photoacryl layer 120 is formed in the reflective region where the TFT transistor on the array substrate 200 side is provided. An SiN layer 121 is provided on the photoacryl layer 120 in the reflective region and the gate insulating layer 101 in the transparent region. A reflective electrode 103 is formed on the SiN layer 121 in the reflective region. An ITO transparent electrode 108 is provided on the reflective electrode 103 in the reflective region and the SiN layer 121 in the transmissive region. Further, an alignment film (not shown) is applied on the ITO transparent electrode 108. A contact hole 122 is formed through the photoacrylic layer 120 and the SiN layer 121, and the reflective electrode 103, the ITO transparent electrode 108, and the source electrode 107 are electrically connected through the contact hole 122. . On the other hand, a color filter layer 111 is formed on the second substrate 110 on the color filter substrate 201 side. In addition, as shown in FIG. 2, a hole 114 from which a color layer is removed is formed in a part of the color filter layer 111, and the first overcoat layer (transparent resin) is formed in the hole 114 from which the color layer has been removed. Layer) 115 is buried. A common electrode (not shown) is formed on the color filter layer 111 and the first overcoat layer 115. Furthermore, a rivet 113 is formed thereon. An alignment film (not shown) is applied on the color filter layer 111 and the rivet 113. Since other configurations are basically the same as those in FIG. 1, the same reference numerals are given and description thereof is omitted here.

  In the conventional example of FIG. 2, as the transparent resin layer provided on the color filter substrate 201 side, only the first overcoat layer (transparent resin layer) 115 is provided because it is only necessary to fill the hole 114 from which the color layer is removed. Good. Thereby, since the process for forming an overcoat layer will be only once, manufacturing cost can be held down.

  However, the conventional example shown in FIG. 2 has a problem of how to connect the reflective electrode 103 or the ITO transparent electrode 108 and the source electrode 107 extending from the thin film transistor Tr. In the conventional example shown in FIG. 2, a contact hole 122 is provided in the center of the reflective region where the reflective electrode 103 is provided, and the reflective electrode 103 or the ITO transparent electrode 108 is connected to the source electrode 107. It was. In this case, since there is the contact hole 122, a columnar spacer (see 104 in FIG. 1) for securing the cell gap cannot be provided in the reflective region, and thus the columnar spacer has been provided outside the pixel region. It was. However, since the columnar spacer itself has an alignment regulating ability and performs an operation different from that of the contact hole 122, the orientation regulating orientation is inconsistent with the original alignment of the liquid crystal. For this reason, there is a problem that an afterimage occurs when the image displayed on the liquid crystal display device is switched, and the cost is low. For example, when a black square is displayed on a white background and the entire screen is switched to white, there is a problem that a defect such that a black square trace is observed for several seconds occurs. Furthermore, since the contact hole 122 is provided through the photoacrylic layer 120 and the SiN layer 121, the depth and diameter of the contact hole 122 are large, and there is a problem that the influence on the alignment of liquid crystal molecules is large. It was.

  The present invention has been made to solve such problems, and an object of the present invention is to obtain a liquid crystal display device capable of preventing the occurrence of an afterimage at the time of video switching while suppressing the manufacturing cost.

  The present invention drives a pixel in a liquid crystal display device comprising an array substrate, a color filter substrate, and a liquid crystal layer filled between the substrates, and one pixel is divided into a plurality of sub-pixels. A contact hole for electrically connecting a voltage supply electrode provided in the thin film transistor for applying a voltage to an electrode for applying a voltage to the liquid crystal layer is provided in a connection portion connecting the sub-pixels to each other. It is a liquid crystal display device.

  The present invention drives a pixel in a liquid crystal display device comprising an array substrate, a color filter substrate, and a liquid crystal layer filled between the substrates, and one pixel is divided into a plurality of sub-pixels. A contact hole for electrically connecting a voltage supply electrode provided in the thin film transistor for applying a voltage to an electrode for applying a voltage to the liquid crystal layer is provided in a connection portion connecting the sub-pixels to each other. Therefore, it is possible to prevent the occurrence of an afterimage at the time of video switching while suppressing the manufacturing cost.

Embodiment 1 FIG.
Hereinafter, preferred embodiments of a liquid crystal display device according to the present invention will be described with reference to the accompanying drawings. 3 and 4 are a cross-sectional view and a plan view showing the configuration of the liquid crystal display device according to Embodiment 1 of the present invention. 3 and 4 show an A-Si type transflective liquid crystal display device as an example. Further, the resolution is QVGA, and the screen size is 2.4 inches diagonal, which is a vertical alignment type liquid crystal display device. In addition, liquid crystal having a negative dielectric anisotropy is used, and the liquid crystal is vertically aligned when no voltage is applied. However, this is an example, and the present invention is not limited to this.

  3 and 4, 10 is an array substrate, and 30 is a color filter substrate. In the array substrate 10, a gate electrode 14 is formed on a first substrate 11 made of a transparent insulating material. Although only one gate electrode 14 is shown in FIG. 3, a plurality of gate electrodes 14 are actually arranged in parallel on the first substrate. A gate insulating layer 12 for insulating the gate electrode 14 is formed on the first substrate 11 on which the gate electrode 14 is formed. The gate insulating layer 12 substantially intersects the gate electrode 14. Data electrodes 41 (see FIG. 4) are formed. Further, a photoacryl layer 13 for insulating the data electrode and forming a predetermined step is formed on the thin film transistor Tr side (reflection region side) on the gate insulating layer 12 on which the data electrode is formed. The thickness of the photoacrylic layer 13 may be set to an arbitrary thickness as appropriate, but about 2 microns is appropriate. The thin film transistor Tr is provided as a switching element in a region where the gate electrode 14 and the data electrode 41 intersect for each pixel region. The thin film transistor Tr is composed of a gate electrode 14 provided at the lowest level, and a drain electrode 15 and a source electrode (voltage supply electrode) 16 provided above the gate electrode 14 with a gate insulating film 12 interposed therebetween. Has been. An SiN layer 17 is provided on the photoacrylic layer 13 in the reflective region and the gate insulating layer 12 in the transmissive region. A reflective electrode 18 is formed on the SiN layer 17 in the reflective region, and an ITO transparent electrode 19 for applying a voltage to the liquid crystal layer on the reflective electrode 18 in the reflective region and on the SiN layer 17 in the transmissive region. Is provided. An alignment film (not shown) is applied on the ITO transparent electrode 19.

  Furthermore, in the present embodiment, a source electrode extension 16A is formed by extending the source electrode 16. A contact hole 20 for electrically connecting the source electrode extension 16 </ b> A and the ITO transparent electrode 19 is provided through the SiN layer 17. In the present embodiment, as described above, the ITO transparent electrode 19 is provided in both the reflection region where the photoacrylic layer 13 is provided and the transmission region where the photoacrylic layer 13 is not provided. . Naturally, a step is formed at the boundary between the portion where the photoacrylic layer 13 is present and the portion where the photoacrylic layer 13 is not present. The contact hole 20 is formed in a transmission region where the photoacrylic layer 13 is not provided and in a portion close to the step portion (a position separated from the step portion by a minute predetermined distance). The predetermined distance from the step portion is not particularly limited and may be determined as appropriate. In particular, as shown in FIG. 4, when one pixel is divided into a plurality of subpixels, a contact hole 20 is provided at a connection portion connecting the subpixels, and the contact hole 20 is provided. The source electrode 16 is extended to the position by the source electrode extension 16A.

  On the other hand, the color filter substrate 30 includes a color filter layer 32 including a second substrate 31 made of a transparent insulating material, a black matrix formed on the second substrate 31, and a sub color filter layer separated by the black matrix. It has. Further, as shown in FIG. 3, a hole 34 from which a color layer is removed is formed in a part of the color filter layer 32, and an overcoat layer (transparent resin layer) 35 is formed in the hole 34 from which the color layer has been removed. Is buried. On the color filter layer 32 and the overcoat layer 35, a common electrode (not shown) for applying an electric field to the liquid crystal layer in a pair with the pixel electrode formed on the array substrate 10 is formed. Furthermore, a rivet 33 for regulating the orientation is formed thereon. An alignment film (not shown) for determining the initial alignment direction of the liquid crystal is applied on the color filter layer 32 and the rivet 33.

  The configuration of the present embodiment will be further described with reference to FIG. As shown in FIG. 4, on the array substrate 10, a plurality of gate electrodes 14 arranged in parallel, and a plurality of data electrodes 41 substantially intersecting with these gate electrodes 14 and arranged in parallel. And are formed. Each pixel region is defined by the intersection of the gate electrode 14 and the data electrode 41. FIG. 4 shows a pixel area for one unit.

  In each pixel region, a thin film transistor Tr is formed as a switching element for driving the corresponding pixel. In each pixel region, an ITO transparent electrode 19 for applying an electric field to the liquid crystal layer is formed. Here, the ITO transparent electrode 19 may be formed of a transparent conductive material other than ITO. In the present embodiment, as described above, one pixel is divided into a plurality of sub-pixels 43, and the connecting portion (connecting portion) 43A connecting the sub-pixels is as shown in FIG. In addition, the width is smaller than that of the sub-pixel 43.

  In the present embodiment, as described above, the connection portion 43A that connects the sub-pixels close to the stepped portion where the ITO transparent electrode 19 is formed in the transmissive region where the photoacrylic layer 13 is not provided. A contact hole 20 for connecting the source electrode 16 and the ITO transparent electrode 19 is formed, and the source electrode 16 is extended to the position by the source electrode extension 16A. Further, a contact hole 20 is provided in a region where the source electrode extension 16A is provided, and the source electrode 16 and the ITO transparent electrode 19 are electrically connected via the source electrode extension 16A and the contact hole 20. It is connected. The layer structure includes the source electrode 16 or the source electrode extension 16A under the SiN layer 17, and the contact hole 20 is opened through the SiN layer 17, and the ITO transparent electrode 19 is filled in the contact hole 20. Is formed in the contact hole 20 (in FIG. 3, for the sake of simplification, the ITO transparent electrode 19 is not provided in the contact hole 20, but actually, it has entered the contact hole 20. It is provided in the form.) The ITO transparent electrode 19 connects the ITO transparent electrodes that are the sub-pixels 43 to each other.

  In addition, in order to stabilize the orientation of the sub-pixel 43, particularly the reflective region, the orientation stabilizing rivet 33 is arranged at the center of the reflective sub-pixel 43. For example, one of the rivets 33 may be replaced with a spacer made of resist or acrylic resin formed in a column shape on the color filter substrate. That is, this columnar spacer is also arranged at the center of the sub-pixel 43 in the reflection region. The spacer comes into contact with the surface of the reflective electrode 18, but the inclined surface controls the orientation. As a result, it is possible to stabilize the orientation with the columnar spacer as the center, thereby realizing a good display.

  As described above, in this embodiment, the overcoat layer for forming a step is not provided on the color filter substrate 30 side, but is formed on the array substrate 10 side, thereby reducing the manufacturing process and the manufacturing cost. I tried to suppress it. Further, the contact hole 20 for electrically connecting the source electrode 16 and the ITO transparent electrode 19 is close to a step due to the photoacrylic layer 13 of the array substrate, and is connected to a connection portion 43A that connects the sub-pixels 43 in the transmission region. Since the source electrode 16 is extended to the position by the source electrode extension 16A, the contact hole 20 is formed only in the SiN layer 17, so that the depth and diameter are small, and the liquid crystal The influence on molecular orientation can be greatly suppressed. Further, since the connection portion 43A portion between the sub-pixels 43 originally originally had liquid crystal molecules that were easily aligned vertically and contributed little to white luminance and was originally black, the contact hole 20 was provided in the connection portion 43A. Even if an opaque region called the source electrode extension portion 16A comes to the connection portion 43A, the decrease in white luminance can be minimized.

  In order to stabilize the orientation of the connection portion 43A, as shown in FIG. 5, the common electrode extension portion which is a common potential layer between both sides of the connection portion 43A connecting the subpixels 43 and between the subpixels 43. 50 may be provided. A transparent electrode (not shown) on the color filter substrate 30 side has a common voltage, and has the same potential as the common electrode 45 on the array substrate 10 side. As a result, the liquid crystal molecules are aligned vertically in the connection portion 43A, and the alignment can be divided into portions on both sides of the connection portion 43A. In addition, an electric field is generated between the common electrode 45 and the ITO transparent electrode 19 on the array substrate. This electric field also has an effect of stabilizing the alignment of liquid crystal molecules. As for the layer structure, the common electrode 45 and the SiN layer 17 are formed in the space between the sub-pixels, and the common electrode 45, the SiN layer 17, the source electrode 16, and the contact hole 20 (or the SiN layer) are formed in the connection portion 43A. ), An ITO transparent electrode 19.

  In the first embodiment, the vertical alignment type liquid crystal display device is taken as an example, but it goes without saying that the present invention is also effective for horizontal alignment, ECB, and IPS types.

It is sectional drawing which showed the structure of the conventional liquid crystal display device. It is sectional drawing which showed the structure of the other conventional liquid crystal display device. It is sectional drawing which showed the structure of the liquid crystal display device which concerns on Embodiment 1 of this invention. It is the top view which showed the structure of the liquid crystal display device which concerns on Embodiment 1 of this invention. It is the top view which showed the structure of the modification of the liquid crystal display device which concerns on Embodiment 1 of this invention.

Explanation of symbols

10 array substrate, 11 first substrate, 12 gate insulating layer, 13 photoacrylic layer, 14 gate electrode, 15 drain electrode, 16 source electrode, 16A source electrode extension, 17 SiN layer, 18 reflective electrode, 19 ITO transparent electrode, 20 contact hole, 30 color filter substrate, 31 second substrate, 32 color filter layer, 33 rivet, 34 hole with color layer removed, 35 overcoat layer, 41 data electrode, 43 subpixel, 43A connection, 45 common electrode 50 common electrode extension, 100 first substrate, 101 gate insulating layer, 102 photoacrylic layer, 103 reflective electrode, 104 columnar spacer, 105 gate electrode, 107 source electrode, 108 ITO transparent electrode, 110 second substrate, 111 color Filter layer, 112 First overcoat layer, 113 Tsu DOO, holes disconnect the 114-color layer, 115 second overcoat layer, 120 photoacryl layer, 121 SiN layer, 122 a contact hole, 200 array substrate, 201 a color filter substrate.

Claims (4)

In a liquid crystal display device that is composed of an array substrate, a color filter substrate, and a liquid crystal layer filled between the substrates, and one pixel is divided into a plurality of sub-pixels,
A connection hole for electrically connecting a voltage supply electrode provided in a thin film transistor for driving the pixel and an electrode for applying a voltage to the liquid crystal layer connects the sub-pixels to each other. A liquid crystal display device characterized by being provided in a portion. On the thin film transistor side, a resin layer for forming a step for changing the cell thickness of the liquid crystal layer is provided,
The resin layer covers at least a portion of the thin film transistor;
The liquid crystal display device according to claim 1, wherein the contact hole is disposed in a region where the resin layer is not provided and in the vicinity of the step. A reflective electrode is provided on the resin layer to form a reflective display region;
3. The liquid crystal display device according to claim 2, wherein a columnar protrusion for holding a cell gap is provided at a central portion of the reflective display region. 4. The liquid crystal display device according to claim 1, wherein a common potential layer is provided on both sides of a connection portion connecting the sub-pixels and between the sub-pixels. 5.

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