JP2005338142A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device in which the outer circumferential region with an area determined by a width in the configuration direction of a connecting pad row is reduced by arranging routing wires in straight lines and in parallel with one another, and the resistance of the routing wires is uniformized. <P>SOLUTION: The liquid crystal display device in which the outer circumferential region with the area determined by the width of the connecting pad row is reduced by reducing the number of the connecting pads 103 is provided by using the liquid crystal display device with the pixel width larger than, and with the display similar to, the conventional one by changing a configuration method of color filters 105 and using sub-pixel rendering. In addition, the liquid crystal display device with the uniformized resistance of the routing wires 104 is simply provided without changing the manufacturing step by arranging the routing wires in straight lines and in parallel with one another. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device in which routing wiring is linearized.

  In recent years, with the full-scale advancement of an advanced video and information society and the rapid spread of multimedia systems, the importance of liquid crystal display devices that play a leading role in flat panel displays is increasing. The liquid crystal display device was born from the liquid crystal discovered by F. Reinizer in 1888 and the thin film transistor invented by P. Weimer in 1961, and its development and application development continue to progress. In addition, the needs for liquid crystal display devices are continually diversifying and expanding, and expectations are growing for new possibilities.

  There are two types of driving methods for liquid crystal display devices, segment electrode driving and matrix electrode driving, depending on the difference in electrode configuration for applying a voltage to the liquid crystal. The latter is classified into passive matrix driving and active matrix driving due to the difference in the electric addressing method. In the passive matrix driving, the intersection of the scanning electrode and the signal electrode corresponds to the pixel, and the driving signal is directly applied. Typically, the scan electrode and the signal electrode are formed on separate glass substrates, crossed over each other, and a liquid crystal is sandwiched therebetween.

  Hereinafter, a passive matrix liquid crystal display device will be described as an example. In the conventional TN type liquid crystal display device, nematic liquid crystal having positive dielectric anisotropy is sealed between two electrode substrates on which transparent electrodes made of ITO are formed so as to have a 90-degree spiral structure. A polarizing plate was disposed on the outside. The liquid crystal display device having such a twist angle has problems such as viewing angle characteristics and the limit of the number of time divisions.

  However, in Apll. Phys. Lett., 45, 1021 (1984), an STN type liquid crystal display device has been proposed in which the twist angle is made larger than 180 degrees and the birefringence effect is used to increase the number of time divisions.

  In the STN type liquid crystal display device, there is a pair of substrates disposed to face each other with a liquid crystal layer interposed therebetween, and the electrodes forming the display region formed on the side of the pair of substrates in contact with the liquid crystal layer are The wiring is arranged at a higher density than the arrangement density of the electrodes from the display area and is connected to the lead-out wiring led out to the periphery of the substrate.

  As one method for connecting drive circuits, a chip-on-glass system has been proposed in which a drive circuit is directly mounted on one peripheral surface of the pair of substrates. In such a case, it is necessary to connect the routing wirings corresponding to the two opposing substrates constituting the panel. For this connection, a conductor such as a conductive bead is used to connect each routing wiring at a connection pad portion formed on two substrates and connected to each routing wiring. In the case of a high-definition liquid crystal display device, since the pixel pitch is small and the lead wirings are arranged with high density, the width of the connection pad row in the arrangement direction with respect to the display region becomes large. Therefore, since the size of the panel is determined by the width of the connection pad row in the arrangement direction, reduction of the panel size is an important issue.

  FIG. 4 shows a schematic diagram of the lead-out wiring of the connection pad portion of the liquid crystal display device using the prior art. 11 is a substrate made of glass, 12 is a display area for displaying an image composed of a plurality of pixels, 13 is a connection pad for connecting routing wires formed on two substrates, and 14 is in the display area 12. A plurality of electrode wirings (not shown) are connected to the connection pads 13. The connection pad 13 is connected to a connection pad formed on a counter substrate (not shown) via a conductor (not shown), and is further mounted on the counter substrate by a lead wiring formed on the counter substrate. Connected to a circuit (not shown). In the case of a high-definition liquid crystal display device, since the number of pixels is large, the number of connection pads 13 is large. Therefore, the connection pad 13 protrudes to the left and right outside of the display area 12, and the width of the outer peripheral area outside the display area is increased.

  FIG. 5 is an enlarged view of a part of FIG. The same reference numerals as those in FIG. 4 denote the same elements, and a description thereof is omitted. Reference numeral 15 denotes an array of RGB patterns of the color filter layer corresponding to each pixel composed of intersections of a plurality of electrode lines existing in the display area 12. 15a indicates red (R), 15b indicates green (G), and 15c indicates blue (B). Since the arrangement of the connection pads 13 protrudes outside the display area 12, the length of the routing wiring 14 that connects the connection pad 13 and the electrode wiring is greatly different at the center and the end of the display area 12. Accordingly, the resistance values of the routing wirings 14 are different, which adversely affects the display performance.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses reduction of the panel size by reducing the size of the peripheral area outside the display area. Specifically, both the scanning electrode driving circuit and the signal electrode driving circuit are provided on one side of the upper side of the panel, and the electrode and the driving circuit are connected to each other through a wiring. Further, a part of the routing wiring is connected to routing wiring of different layers through contact holes, and has a multilayer wiring structure of two or more layers arranged so as to overlap with other routing wiring via an interlayer insulating film. As a result, the routing wiring connected to the scanning electrode wiring and the signal electrode wiring is routed around the image display portion on the substrate, and the scanning electrode side terminal and the signal electrode side terminal are juxtaposed on one side of the substrate. Can be reduced. In addition, since a part of the routing wiring is converted into routing wiring of different layers through a contact hole, and a multi-layer structure of two or more layers arranged so as to overlap with other routing wiring via an interlayer insulating film, Furthermore, the area occupied by the routing wiring portion can be reduced.

Regarding the uniformization of the wiring resistance value, Patent Document 2 discloses that the wiring resistance value is uniform for all wirings. Specifically, the wiring resistance value is made uniform by the wiring length and the wiring width. Since there is a problem that a disconnection failure occurs in the central wiring with a small interconnect width, the line width is set to a certain level or more so that the disconnection failure does not occur, and the resistance value of the internal wiring group that connects the pixel electrode and the terminal electrode is set to the outside. The value is different from the central part.
JP 09-311341 JP 11-38429 A

  In the conventional method, the number of manufacturing steps increases, for example, the production of an interlayer insulating film and the resistance value of each wiring are changed in order to make the resistance value of the routing wiring constant.

  The present invention has been made against the background described above, and a first object of the present invention is to reduce the outer peripheral area outside the display area, which is determined by the width in the arrangement direction of the connection pad row. It is to provide a display device. A second object is to provide a liquid crystal display device in which the resistance value of the routing wiring is made uniform.

  A liquid crystal display device according to a first aspect of the present invention is a liquid crystal display device including a display area for displaying an image and an outer peripheral area outside the display area, the first substrate, and the second substrate A substrate, a liquid crystal layer sealed between the inner surface of the first substrate and the inner surface of the second substrate, and a plurality of first layers formed on the inner surface of the first substrate in the display region. In the display region, a plurality of second electrode wirings formed on the inner surface of the second substrate so as to intersect the plurality of first electrode wirings, and alternately along the first electrode wirings Arranged along the first electrode wiring adjacent to the first column and / or the second column, and the first column and the second column composed of two colored layers arranged in A third row composed of a colored layer of one color different from the colored layers of the two colors. A filter layer; a plurality of first connection pads formed in the outer peripheral region on the first substrate and juxtaposed along a specific side of the first substrate; the plurality of first connection pads; and the display All of the plurality of first electrode wirings included in the region are connected to each other, and a plurality of routing wirings extending in one direction and arranged in parallel to each other are provided. By having such a configuration, the number of first connection pads can be reduced, and the size of the outer peripheral region determined from the width in the arrangement direction of the first connection pad rows can be reduced. In addition, the resistance values of the routing wires are uniform, which is beneficial for display performance.

  Preferably, the plurality of first electrode wirings extend in one direction and are arranged in parallel to each other, and each of the plurality of routing wirings extends in the same direction as the first electrode wiring to be connected. By having such a configuration, it is possible to further reduce the size of the outer peripheral region determined from the width in the arrangement direction of the first connection pad row.

  The second substrate includes a second connection pad at a position facing each of the plurality of first connection pads, and each of the connection pads facing the first substrate and the second substrate is a conductor. It is preferable that it is connected by.

  It is preferable to further include a drive circuit that is disposed on the second substrate in the outer peripheral region and outputs a signal to the second connection pad. With such a configuration, the first electrode wiring is connected to the connection pads facing each other on the first and second substrates via the lead wiring, and is driven by the driving circuit.

  According to the present invention, the size of the outer peripheral area outside the display area determined by the width of the connection pad row in the arrangement direction can be reduced. In addition, since the resistance values of the wirings are uniform, it is possible to have characteristics preferable for image display performance.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, these figures and description illustrate this invention, and do not restrict | limit the scope of the present invention. It goes without saying that other embodiments may belong to the category of the present invention as long as they are consistent with the present invention.

  FIG. 1 shows a schematic diagram of an example of a liquid crystal display device 100 according to the present invention as viewed from the viewing side. In FIG. 1, 101a and 101b are substrates made of glass or the like, 102a and 102b are display areas for displaying an image composed of a plurality of pixels, and 103a and 103b are connection wiring lines formed on two substrates, respectively. The connection pads 104a and 104b are lead wirings for connecting a plurality of electrode wirings (not shown) formed in the display regions 102a and 102b and the connection pads 103, and 106 is a drive circuit for inputting an image signal voltage. is there. FIG. 1A shows a first substrate on the viewing side constituting the panel, and FIG. 1B shows a second substrate on the non-viewing side. A broken line in FIG. 1B indicates a range in which the first substrate 101a is bonded to the second substrate 101b using a sealing agent, and liquid crystal is sealed therebetween. In FIG. 1A, a plurality of first electrode wirings (not shown in 102a) made of transparent electrodes such as ITO are vertically arranged on the opposite side (inside) of the first substrate 101a made of glass or the like. It is extended. In FIG. 1B, on the viewing side of the second substrate 101b, a plurality of second electrode wirings (not shown in 102b) made of transparent electrodes such as ITO are orthogonal to the first electrode wiring. It is formed in the left-right direction. Each of the first and second electrode wirings is formed in a straight line having a constant width, and is arranged in parallel with an adjacent electrode wiring at a predetermined interval.

  Liquid crystal (not shown) is sealed between the first substrate 101a and the second substrate 101b. This liquid crystal is preferably composed of STN liquid crystal. In the STN type liquid crystal display device, the twist angle of the liquid crystal is made larger than 180 degrees, and the birefringence effect is used to increase the number of time divisions and to increase the display information processing amount. In each pixel, active elements are not provided, and the intersection between the scanning electrode and the signal electrode corresponds to the pixel, and passive matrix driving is performed in which a driving signal is directly applied.

  The display area 102 includes a plurality of intersecting portions of the first and second electrode wirings. One intersection corresponds to one pixel. The first and second electrode wirings are connected to a driving circuit 106 formed outside the display area of the second substrate by a lead wiring 104 formed outside the display area 102. Here, an example in which the driving circuit 106 is formed on the second substrate is shown, but the driving circuit 106 may be mounted on any substrate. Further, the connection method of the drive circuit is not limited to the chip-on-glass method in which the drive circuit is directly mounted on the periphery on the substrate, and TAB (Tape automated bonding) may be connected to one of the substrates.

  In FIG. 1A, the plurality of first electrode wirings formed on the substrate 101a and existing in the display region 102a are respectively connected to the first connection pads 103a through the lead wirings 104a. The first electrode wirings extend in the vertical direction on the paper surface and are arranged in parallel to each other. The routing wiring 104a extends in the same direction as the first electrode wiring, and is further arranged in parallel. Further, the routing wiring 104b in FIG. 1B connects the driving circuit 106 with the second electrode wiring formed on the second substrate 101b and extending in the horizontal direction of the drawing. The routing wiring 104b is routed from the second electrode wiring on the second substrate 101b by a distance in the left-right direction on the paper, and then arranged in parallel in the vertical direction with a certain spacing from the adjacent routing wiring. Further, the routing wiring 104b connects the second connection pad 103b on the second substrate 101b and the driving circuit 106 with a straight line. This is not arranged in parallel and does not take a certain length.

  FIG. 2 is a schematic view of the AA ′ cross section of FIG. The plurality of first electrode wirings formed on the first substrate 101a are connected to the first connection pads 103a through the lead wirings 104a. In order to connect the first connection pads 103a to the drive circuits 106 mounted on the substrate 101b, as shown in FIG. 2, the conductors 107 such as conductive beads are interposed on the second substrate 101b. Are connected to the second connection pads 103b. The second connection pad 103b is connected to the lead wiring 104b on the second substrate 101b side which is the counter substrate, and is connected to the drive circuit 106.

  A color filter layer 105 is provided in the display region between the first substrate 101a and the first electrode wiring. The RGB pattern of the color filter layer 105 is formed in a pixel formed by an intersection of the first electrode wiring and the second electrode wiring. The color filter layer 105 may be arranged between the second substrate 101b and the second electrode wiring. The color filter layer 105 has an RGB pattern formed according to a specific color arrangement. The arrangement of the RGB pattern will be described in detail later. A black matrix layer made of resin, metal chrome, or the like may be formed around each RGB pattern. The black matrix layer is provided for improving display performance such as improvement of contrast.

  A protective layer is formed on the color filter layer 105. Since the STN type liquid crystal display device has a larger twist angle than the TN type and requires flatness in the cell, the protective layer is provided to eliminate the unevenness of the color filter layer 105. For the protective layer, an organic material such as acrylic is used.

  Each pixel in the liquid crystal display region 102 applies an electric field to the liquid crystal based on a signal voltage input from the drive circuit 106. Thus, any one of R, G, and B is displayed by birefringence modulation by controlling liquid crystal molecules with a predetermined twist angle and a predetermined alignment direction.

  FIG. 3 is an enlarged view of FIG. The same symbols in the drawings indicate the same items, and the description thereof is omitted. Reference numeral 105 denotes an arrangement of RGB patterns of the color filter layer. 105a indicates red (R), 105b indicates green (G), and 105c indicates blue (B).

  The arrangement of the RGB pattern shown in FIG. 3 is a combination of one pixel row of one color and two pixel rows in which two different colors are regularly arranged alternately. Yes. More specifically, it consists of one pixel column consisting of B and two pixel columns consisting of RG. Furthermore, the two pixel columns made of RG have a checkered pattern.

  The display uses “sub-pixel rendering” in which the three pixels of the three colors RGB constituting the picture element are further divided for each pixel and individually processed. Typically, “sub-pixel rendering” is one of the methods for making the stepped jaggedness generated in diagonal lines and curves inconspicuous when performing display. Conventionally, in a liquid crystal display device, three pixels of RGB three colors form one picture element, and one picture element in the image to be displayed is formed, so the display appears as a collection of picture elements arranged in a grid. However, when the resolution is low, in principle, a jagged portion is always generated in portions other than the horizontal portion and the vertical portion. In order to make this inconspicuous, intermediate color picture elements are arranged around the boundary line.

  By using an RGB pattern arrangement of a specific color filter layer as shown in FIG. 3 and “sub-pixel rendering” of a predetermined display method, a physical picture is used using four or more associated pixels. It is possible to display more logical picture elements than prime numbers. An example of the above display method will be described in detail.

  For the display, a first pixel that performs display and a plurality of second pixels that are associated with each other and perform display that is darker than the first pixel are used. More specifically, since the resolution information detected by the human eye is mainly detected by the R and G pixels, a more approximate display is performed with the first R or G pixel, and the pixels are arranged on the left and right sides of the pixel. The R or G pixel and the B pixel that are to be displayed, and the R or G pixel that is disposed above and below are simultaneously displayed with a darker luminance than the first pixel. Further, the gradation of each second pixel is controlled, and a display with substantially the same resolution as the conventional display can be performed.

  As an example of the above display method, when the display is performed using G of 105b in FIG. 3 as the first pixel, R arranged above and below 105b, R arranged on the left, and arranged on the right B (105c) and R arranged on the right side of B (105c) are simultaneously displayed in a darker display than that of 105b. As a result, even with a smaller number of pixels than in the prior art, it is possible to display with a resolution substantially equivalent to that of the prior art.

  By using the RGB pattern arrangement and the display method as described above, it is possible to perform display with substantially the same resolution as in the past with a smaller number of pixels than in the past. When the size of the display area is determined, the number of pixels can be reduced as compared with the conventional case, and the number of electrode wirings can be reduced. Accordingly, the number of first connection pads 103a is also reduced, and the first connection pads 103a are not disposed outside the width of the display area.

  Therefore, the routing wiring 104a is connected from the first electrode wiring to the first connection pad 103a in a straight line in the same direction as the extending direction of the first electrode wiring (up and down direction on the paper surface), and each is arranged in parallel. The size of the panel can be reduced. Further, as shown in FIG. 3, the width of the routing wiring is reduced at a constant rate from the first electrode wiring width to the first connection pad width while being connected from the first electrode wiring to the first connection pad. You may do it. The width of the routing wiring may take a constant value, and is not limited to the example shown here.

  Further, by connecting as described above, since the lengths of the wirings at the center and the end of the display area are the same, the resistance values are the same and the influence on the display performance can be reduced. Furthermore, the resistance of the routing wiring is conventionally made to increase according to the wiring having a high resistance, but the resistance can be lowered as compared with the conventional resistance by matching the resistance of the wiring. Therefore, the time required for pattern design can be shortened.

FIG. 3 is a schematic diagram illustrating wiring of the liquid crystal display device according to the first embodiment. It is an enlarged view of the connection pad part of FIG. It is an enlarged view of FIG. It is the schematic which showed the wiring of the liquid crystal display device using a prior art. FIG. 5 is an enlarged view of FIG. 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Substrate 102 Display area 103 Connection pad 104 Leading wiring 105 Color filter layer 106 Drive circuit 107 Conductor

Claims (5)

A liquid crystal display device comprising a display area for displaying an image and an outer peripheral area outside the display area,
A first substrate;
A second substrate;
A liquid crystal layer sealed between the inner surface of the first substrate and the inner surface of the second substrate;
A plurality of first electrode lines formed on the inner surface of the first substrate in the display region;
A plurality of second electrode wirings formed on the inner surface of the second substrate so as to intersect the plurality of first electrode wirings in the display region;
A first column and a second column composed of colored layers of two colors arranged alternately along the first electrode wiring; and adjacent to the first column and / or the second column A color filter layer comprising: a third row arranged along the first electrode wiring and composed of a colored layer of one color different from the colored layers of the two colors;
A plurality of first connection pads formed in the outer peripheral region on the first substrate and juxtaposed along a specific side of the first substrate;
A plurality of lead wirings connected to each of the plurality of first connection pads and all of the plurality of first electrode wirings included in the display region, extending in one direction and arranged in parallel to each other;
A liquid crystal display device. The plurality of first electrode wires extend in one direction and are arranged in parallel to each other,
2. The liquid crystal display device according to claim 1, wherein each of the plurality of lead wirings extends in the same direction as the first electrode wiring to be connected. The second substrate includes a second connection pad at a position facing each of the plurality of first connection pads,
Each of the opposing connection pads of the first substrate and the second substrate is connected by a conductor,
The liquid crystal display device according to claim 1. A driving circuit disposed on the second substrate in the outer peripheral region and outputting a signal to the second connection pad;
The liquid crystal display device according to claim 3.   The liquid crystal display device according to claim 1, wherein the liquid crystal display device displays an image in an STN mode.

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