JP2010014973A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a TFT liquid crystal display device having an auxiliary wiring line and a narrow frame region. <P>SOLUTION: The TFT liquid crystal display device 100 has: a TFT substrate 10 including a first substrate 11, and a gate bus line 12 and a source bus line 14 formed on the first substrate, a TFT 16 connected to these lines, and a pixel electrode 17 connected to the source bus line through the TFT; a counter substrate 20 including a second substrate 21, and a black matrix 26 and a counter electrode 22 fabricated on the second substrate; and a liquid crystal layer 30 disposed between the TFT substrate and the counter substrate. The TFT substrate further has an auxiliary wiring line 18 disposed as intersecting the gate bus line and the source bas line via an insulating layer and having a portion opposing to the counter electrode and the black matrix via the liquid crystal layer. The portion of the black matrix 26, opposite the auxiliary wiring line 18, includes a portion 26a having a smaller thickness than in other portion. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly to an active matrix liquid crystal display device including a TFT as a switching element.

  An active matrix type liquid crystal display device (hereinafter referred to as a TFT type liquid crystal display device) including a TFT as a switching element includes a TFT substrate, a counter substrate, and a liquid crystal layer provided therebetween. The TFT substrate has a glass substrate, a source bus line formed on the glass substrate, a gate bus line, a TFT connected to these, and a pixel electrode connected to the source bus line via the TFT. is doing. The counter substrate has a glass substrate, a color filter layer formed on the glass substrate, a black matrix, and a counter electrode. Furthermore, the liquid crystal display device is further provided with an alignment film, a polarizing plate, a retardation plate, and the like as necessary.

  Disconnection may occur in the gate bus line and source bar line of the TFT substrate. Causes of the disconnection include stress migration, base level difference, and manufacturing defects.

  When a disconnection occurs in a gate bus line or a source bus line, a pixel associated with the bus line via a TFT becomes a defect, so that a linear display defect occurs.

In order to prevent the occurrence of a linear display defect, a method for repairing the disconnection by providing an auxiliary wiring has been conventionally proposed. For example, in Patent Document 1, auxiliary wiring is provided outside the display area and outside the frame of the counter substrate so as to intersect the gate bus line and the source bus line via an insulating film, A method of electrically shorting a portion where the crossing points is disclosed.
Japanese Patent Laid-Open No. 5-203986

  However, in order to adopt the configuration of Patent Document 1, it is necessary to provide an area for forming the auxiliary wiring outside the frame of the counter substrate, so that the frame area (area outside the display area) of the liquid crystal display device is increased. There's a problem.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a TFT liquid crystal display device having auxiliary wiring and a narrow frame area.

  The liquid crystal display device of the present invention includes a first substrate, a gate bus line formed on the first substrate, a source bus line, a TFT connected to the gate bus line and the source bus line, A TFT substrate having a pixel electrode connected to the source bus line through the TFT, a second substrate, a black matrix formed on the second substrate, and a counter substrate having a counter electrode; A TFT type liquid crystal display device having a liquid crystal layer provided between a TFT substrate and the counter substrate, wherein the TFT substrate intersects the gate bus line and the source bus line via an insulating layer. And an auxiliary wiring including a portion facing the counter electrode and the black matrix via the liquid crystal layer, and the black matrix The auxiliary line and facing portions of the scan is characterized in that it comprises a portion which is thinner than the other portions.

  In one embodiment, a portion of the black matrix facing the auxiliary wiring includes a through hole.

  In one embodiment, the black matrix is formed of a black resin layer.

  According to the present invention, a TFT type liquid crystal display device having auxiliary wiring and having a narrow frame area is provided.

  Hereinafter, a TFT liquid crystal display device according to an embodiment of the present invention will be described with reference to the drawings.

  1 and 2 schematically show the structure of a TFT liquid crystal display device 100 according to an embodiment of the present invention. FIG. 1 is a schematic plan view of the liquid crystal display device 100, and FIG. 2 is a schematic partial cross-sectional view of the liquid crystal display device 100 along the line AB in FIG.

  The liquid crystal display device 100 includes a TFT substrate 10, a counter substrate (color filter substrate) 20, and a liquid crystal layer 30 provided between the TFT substrate 10 and the counter substrate 20.

  The TFT substrate 10 includes a glass substrate 11, a gate bus line 12 formed on the glass substrate 11, a source bus line 14, a TFT 16 connected to the gate bus line 12 and the source bus line 14, and the TFT 16. And a pixel electrode 17 connected to the source bus line 14.

  The counter substrate 20 includes a glass substrate 21, a color filter layer 24, a black matrix 26, and a counter electrode 22 formed on the glass substrate 21. Note that the color filter layer 24 may be omitted. The liquid crystal display device 100 has a display area (sometimes referred to as an “active area”) 10D and a frame area 10F outside the display area 10D, and the color filter layer 24 is formed in the display area 10D. The black matrix 26 is formed in the frame area 10F. The frame area 10F indicates the entire non-display area outside the display area 10D, and includes the area of the TFT substrate 10 outside the counter substrate 20.

  The TFT substrate 10 is provided so as to intersect the gate bus line 12 and the source bus line 14 via an insulating layer (not shown), and a portion facing the counter electrode 22 and the black matrix 26 via the liquid crystal layer 30. A further auxiliary wiring 18 is included. The auxiliary wiring 18 is entirely formed in a region facing the counter electrode 22 and the black matrix 26.

  Here, the auxiliary wiring 18 is formed in a U-shape having two straight portions parallel to the gate bus line 12 and one straight portion parallel to the source bus line 14 in the frame region 10F. However, the present invention is not limited to this, and it may be formed in a square shape surrounding the display area 10D. Note that the number of auxiliary wirings 18 can be appropriately set in consideration of the occurrence rate of disconnection.

  When the disconnection 14o occurs in one of the source bus lines 14, the source bus line 14 below the disconnection portion 14o (the side separated from the source input terminal indicated by □) in FIG. Since the source signal (display signal) is not supplied to the connected pixel electrode 17, a linear display defect occurs. At this time, the source bus line 14 and the auxiliary wiring 18 are short-circuited at the two portions 14a and 14b where the source bus line 14 where the disconnection has occurred and the auxiliary wiring 18 intersect. When the source bus line 14 thus disconnected is connected to the auxiliary wiring 18 at two locations, source signals (display signals) are supplied to the source bus line 14 from both sides, and therefore connected to the source bus line 14. A source signal is supplied to all the pixel electrodes 17 that have been formed, and the linear display defects are repaired.

  At this time, the wiring path to the pixel electrode 17 to which the source signal is supplied via the source bus line 14 connected to the auxiliary wiring 18 is more than the wiring path to the pixel electrode 17 connected to the normal source bus line 14. Also long. Therefore, the electrical resistance of the auxiliary wiring 18 is preferably low, and the auxiliary wiring 18 is preferably short.

  In the configuration described in Patent Document 1, the auxiliary wiring is provided outside the display area and outside the frame of the counter substrate, whereas in the liquid crystal display device 100, the auxiliary wiring 18 is provided in the area facing the counter electrode 22. Therefore, there is an advantage that the auxiliary wiring 18 can be shortened and the frame region 10F can be narrowed.

  However, if the auxiliary wiring 18 is simply formed in a region facing the counter electrode 22, the source signal is delayed due to the parasitic capacitance between the auxiliary wiring 18 and the counter electrode 22. The liquid crystal display device 100 of this embodiment solves this problem as follows.

  As shown in FIG. 2, in the liquid crystal display device 100 of the present embodiment, the portion of the black matrix 26 that faces the auxiliary wiring 18 includes a through hole 26a. That is, the liquid crystal layer 30 existing between the auxiliary wiring 18 and the counter electrode 22 includes a portion that is thicker than the other portions by the thickness of the black matrix 26. By having such a configuration, the parasitic capacitance formed between the auxiliary wiring 18 and the counter electrode 22 can be reduced. A recess may be formed instead of the through hole 26a of the black matrix 26, and a portion having a smaller thickness than other portions may be provided in a portion facing the auxiliary wiring 18 of the black matrix 26. Of course, from the viewpoint of reducing the parasitic capacitance, it is preferable that the entire portion of the black matrix 26 facing the auxiliary wiring 18 is the through hole 26a.

  The black matrix 26 is preferably formed using a black resin layer, and the thickness is preferably about 1 μm to 3 μm. In addition, when a black resin having photosensitivity is used, the through holes 26a or the recesses can be easily formed using a photolithography process.

  FIG. 3 shows a schematic sectional view of a TFT type liquid crystal display device 200 of a comparative example. The same components as those of the liquid crystal display device 100 are denoted by common reference numerals, and description thereof is omitted.

  In the liquid crystal display device 200, the black matrix 26 'is formed with a constant thickness, and the portion facing the auxiliary wiring 18 has the same thickness as the other portions. If the auxiliary wiring 18 described in Patent Document 1 is simply provided at a position facing the counter electrode 22 as in the liquid crystal display device 200 in order to narrow the frame region 10F, the auxiliary wiring 18 and the counter electrode 22 A parasitic capacitance is formed between the two and causes a delay of the source signal.

  As is clear from a comparison between FIG. 2 and FIG. 3, the liquid crystal display device 100 of the present embodiment includes a portion 26a where the portion of the black matrix 26 facing the auxiliary wiring 18 has a smaller thickness than the other portions. Therefore, the parasitic capacitance formed between the auxiliary wiring 18 and the counter electrode 22 is smaller than that of the liquid crystal display device 200, and the delay of the source signal is suppressed.

  Although the case where the disconnection 14o occurs in the source bus line 14 has been described here, the same applies to the case where the disconnection occurs in the gate bus line 12.

  As a method of short-circuiting the auxiliary wiring 18 and the source bus line 14 or the gate bus line 12, various known methods such as a laser irradiation method can be used.

  The present invention can be widely used for TFT liquid crystal display devices.

It is a typical top view of TFT type liquid crystal display device 100 of an embodiment by the present invention. It is a typical fragmentary sectional view of the liquid crystal display device 100 along the AB line | wire of FIG. It is typical sectional drawing of the TFT type liquid crystal display device 200 of a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 TFT substrate 11, 21 Glass substrate 12 Gate bus line 14 Source bus line 14o Disconnection part 14a, 14b Connection part 16 TFT
17 Pixel electrode 18 Auxiliary wiring 20 Counter substrate 22 Counter electrode 24 Color filter layer 26 Black matrix 26a Through hole

Claims (3)

A first bus; a gate bus line; a source bus line; a TFT connected to the gate bus line and the source bus line; and the source bus line via the TFT. A TFT substrate having a pixel electrode connected to
A counter substrate having a second substrate, a black matrix formed on the second substrate, and a counter electrode;
A TFT type liquid crystal display device having a liquid crystal layer provided between the TFT substrate and the counter substrate,
The TFT substrate is provided so as to intersect the gate bus line and the source bus line via an insulating layer, and includes an auxiliary wiring including a portion facing the counter electrode and the black matrix via the liquid crystal layer Further comprising
The liquid crystal display device, wherein a portion of the black matrix facing the auxiliary wiring includes a portion having a smaller thickness than other portions.   The liquid crystal display device according to claim 1, wherein a portion of the black matrix facing the auxiliary wiring includes a through hole.   The liquid crystal display device according to claim 1, wherein the black matrix is formed of a black resin layer.

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