JP2001235723A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problems that two systems of gate driving circuits are necessary for a system for driving a liquid crystal display device from both sides of gate signal wiring and this causes increase in costs, man-hours for production, and device size, and decrease in reliability due to increase in the number of contacts, and moreover, that with enlargement of a display screen, waveforms of driving signals are largely distorted as the signal goes from the supply side to the end side, and this causes gradient of brightness, flickering, etc., and results in impairment of display uniformity. SOLUTION: A liquid crystal display is configured so that scanning signals supplied from gate driving circuits are applied to the center part of gate signal wiring or video signals supplied from source driving circuits are applied to the center part of source signal wiring. Moreover, a light crystal display device, in which the gate wiring or source wiring is driven from both sides, is configured so that the signals supplied from the gate or source driving circuits are applied to both sides and a middle point between respective both sides of the gate or source signal wiring and the center part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly to a liquid crystal display capable of displaying a large screen or a high resolution.

[0002]

2. Description of the Related Art Active matrix type liquid crystal displays using thin film transistors (TFTs) are advantageous in that they are thin, light, and can be driven at a low voltage, so that they can be used for displays for camcorders, personal computers, and personal computers. It is used in various fields such as processor displays and forms a large market.

[0003] In recent years, in recent years, in personal computer applications, a large amount of information has been acquired via the Internet or the like, daily communication has been performed by e-mail, and video has been displayed by linking to AV equipment. In addition to the use, more and more information is handled, and accordingly, a demand for a large screen and high resolution capable of displaying more information on a display is increasing.

In order to realize a large screen and a high resolution of a liquid crystal display device, a decrease in display performance caused by an increase in the number of display pixels and a high density, for example, an increase in crosstalk and flicker, and an increase in the number of pixels, It is indispensable to solve problems such as display unevenness due to insufficient charging. To solve this problem, driving at the same timing from both ends of the gate signal wiring enables the difference in brightness between the left and right of the liquid crystal display element and the crossover. Japanese Patent Laid-Open No. 3-274 discloses a liquid crystal display device in which a talk is eliminated.
No. 526 has been proposed.

Hereinafter, a conventional liquid crystal display device will be described with reference to the drawings.

FIG. 7 is a diagram showing a configuration of a conventional liquid crystal display device. In FIG. 7, source signal driving circuits 3a and 3b are connected to both ends of the source signal wiring 2 of the liquid crystal display element 1,
Gate drive circuits 5a, 5b are provided at both ends of the gate signal line 4.
Is connected. Each wiring end is connected to a driving circuit, and the source driving circuits 3a and 3b, the gate driving circuit 5
A control signal or power is supplied from a controller 6 to a drive circuit element such as an IC on a and 5b via a flat cable 7.

According to the above configuration, even if the resistance or the parasitic capacitance of the gate signal wiring increases due to the increase in the screen size or the resolution of the liquid crystal display device, the same signal is applied to both ends of the liquid crystal display element of the gate signal wiring. By driving at the timing, the wiring resistance and the capacitance on the wiring can be substantially halved, thereby suppressing the delay of the scanning signal and eliminating the difference in brightness and unevenness between the left and right of the liquid crystal display element. I have.

[0008]

However, in the above-described conventional liquid crystal display device, two systems of gate drive circuits are required to drive from both sides of the gate signal wiring, resulting in an increase in cost, an increase in production man-hours, and Problems such as an increase in the size of the device and a decrease in reliability due to an increase in the number of contacts will occur. In the case of having a very large screen size and resolution, even if driving is performed from both sides, the waveform of the driving signal is greatly distorted as going from the signal supply side to the terminal side, and a luminance gradient or flicker occurs. There is a problem that display uniformity is impaired.

The present invention has been made in view of the inconvenience of the above-mentioned conventional liquid crystal display device. Even if the liquid crystal display device has a large screen and high resolution, it is low in cost and does not increase the number of steps and size. An object of the present invention is to provide a liquid crystal display device with no performance degradation.

[0010]

In order to achieve the above object, the liquid crystal display of the present invention has at least the following constitution.

The means 1 is configured so that the scanning signal supplied from the gate drive circuit is applied to the center of the gate signal wiring. With this configuration, the gate drive circuit can be reduced to one system, and the wiring resistance and the parasitic capacitance from the signal supply position to the end of the gate wiring farthest can be made the same as the conventional double-sided drive. As in the case of the display device, it is possible to obtain a liquid crystal panel in which a difference in luminance between left and right and generation of flicker are suppressed.

According to the second aspect, in a liquid crystal display device provided with a gate drive circuit for sequentially supplying a scan signal to both sides of the gate signal line at the same timing, the scan signal supplied from the gate drive circuit is supplied to the gate signal line. Each is configured to be applied to an intermediate point between both ends and the center. With this configuration, the wiring resistance and the parasitic capacitance from the signal supply position to the farthest gate wiring end can be reduced to half that of the conventional double-sided drive. A liquid crystal panel having almost no problem can be obtained.

The means 3 is configured so that the video signal supplied from the source drive circuit is applied to the center of the source signal wiring. With this configuration, the number of source drive circuits can be reduced to one, and the wiring resistance and the parasitic capacitance from the signal supply position to the farthest source wiring end can be made the same as in the conventional double-sided drive. As in the case of the display device, it is possible to obtain a liquid crystal panel in which the occurrence of a difference in luminance between upper and lower portions and flicker is suppressed.

According to the means 4, in a liquid crystal display device provided with a source drive circuit for supplying a video signal to the source signal wiring from both sides at the same timing, the video signals supplied from the source drive circuit are respectively supplied to the source signal wiring. It is configured to be applied to an intermediate point between both ends and the center. With this configuration, the wiring resistance and the parasitic capacitance from the signal supply position to the end of the source wiring farthest can be reduced to half that of the conventional double-sided drive. A liquid crystal panel having almost no problem can be obtained.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a liquid crystal display device of the present invention will be described more specifically with reference to the drawings. However, in the following description of the drawings, the same parts as those in FIG.

Embodiment 1 FIG. 1A is a block diagram showing a liquid crystal display according to Embodiment 1 of the present invention.

In FIG. 1A, reference numeral 1 denotes a liquid crystal display element comprising a pixel 101 of a minimum display unit, and 2 denotes a source signal wiring for supplying a video signal to the liquid crystal display element 1;
Reference numeral b denotes a source drive circuit connected to the electrode terminals at both ends of the source signal wiring 2. The above configuration is the same as that of the conventional one, but the gate signal wiring 4 has a gate signal supply wiring 8 connected to the gate drive circuit 5 at the center. Are connected to each other, from which power is supplied to both sides of the gate signal wiring 4 so that a scanning signal is supplied to the liquid crystal display element 1 equally to the left and right. The connection between each electrode terminal and the drive circuit is made using a flexible printed circuit board called TAB (tape automated bonding) with a drive circuit mounted thereon, and a source drive circuit 3, a gate drive circuit 5, and a controller. Reference numeral 6 is connected by a flat cable 7, and control signals and power are supplied through the flat cable 7.

FIG. 2A shows a gate signal supply line 8.
FIG. 3 is a plan view showing a configuration of a pixel in a portion connected to a gate signal line 4. In FIG. 2A, a gate signal supply line 8 is formed on the same layer as the gate signal line 4 in the same step on an array substrate 14 based on a glass substrate. That is, a film was formed using a metal film containing aluminum as a main component, and a pattern was formed on the same plane by photolithography. The material used for the gate signal wiring is preferably a metal having a low wiring resistance, but is not particularly limited to an aluminum-based metal, and may be a single-layer film or a multilayer film. The source signal wiring 2 is formed in the same manner as the gate signal wiring 4 on a layer in which an insulating layer such as silicon nitride (SiN _x ) is deposited on the layer on which the gate signal wiring 4 is formed by a CVD method or the like. . Reference numeral 10 denotes a pixel electrode, which is formed of a transparent material such as ITO, is connected to the source signal wiring 2 via a thin film transistor (TFT) 11 having a semiconductor layer using amorphous silicon,
The liquid crystal is controlled between a counter electrode provided on a counter substrate.

In the liquid crystal display device configured as described above, since the scanning signal is supplied to the center of each gate signal line, the scanning signal can be supplied evenly to the left and right even with a single gate drive circuit. In addition, the wiring resistance and the parasitic capacitance from the signal supply position to the end of the gate wiring farthest from the signal supply position can be made the same as in the conventional double-sided driving, so that the luminance difference and flicker on the left and right sides of the screen can be eliminated.

Note that, as shown in FIG. 1B, even when the source signal driving circuit is a single system, the above-described effect is not changed.
Further, as shown in FIG. 2B, the gate signal supply wiring 8 may have an extended shape even after the portion connected to the gate signal wiring 4. In this case, the pixel configuration becomes more uniform on the left and right sides of the connection portion, and the occurrence of imbalance on the left and right sides can be suppressed.

Further, as shown in FIG. 1C, the gate supply terminal 8c is provided so that the path of the gate signal supply line 8 from the gate drive circuit 5 to the gate signal line 4 can be divided into two systems.
It is also effective to provide. If the scanning signal is supplied using only one of these systems, the remaining system is connected to the gate supply terminal 8 even if the signal supply from this system is broken.
c to the gate drive circuit 5 to supply a signal. Although the number of driving circuits increases, signals can be supplied from both ends.

In the present embodiment, TN (Twisted-
Nematic) liquid crystal display devices are described, but other methods of controlling liquid crystal by electrodes provided on upper and lower substrates facing each other, and liquid crystal is provided on one of two opposed substrates. (In-Plane-Switc) having a pixel electrode and a counter electrode for driving the pixel
hing) type liquid crystal display device.

(Embodiment 2) FIG. 2C is a plan view showing one pixel of a liquid crystal display device according to Embodiment 2 of the present invention, and FIGS. 2D, 2E and 2C. f) is the A-
It is A 'sectional drawing.

2 (c) and 2 (d) are different from the first embodiment in that the gate signal supply line 8 is formed below the gate signal line 4 via the insulating layer 12a.
The point is that the connection portion 13 a provided in the insulating layer 12 is connected to the gate signal wiring 4.

According to the above configuration, the gate signal supply wiring 8
And the gate signal wiring 4 can be overlapped on the display surface, so that the area shielded by the wiring can be reduced without changing the wiring area of each wiring, so that the aperture ratio can be improved and a bright liquid crystal display device can be obtained. Can be done.

The configuration in which the gate signal supply wiring 8 and the gate signal wiring 4 are overlapped in the display surface is shown in FIGS.
The configuration is not limited to the configuration shown in FIG.
As shown in (e), the gate signal supply wiring 8 and the gate signal wiring 4 may be switched between upper and lower layers, and another insulating layer or source wiring may be provided between the gate signal supply wiring 8 and the gate signal wiring 4. And other layers for forming wiring. For example, as shown in FIG. 2F, the gate signal supply wiring 8 may be formed on a counter substrate 16 which faces the array substrate 14 via the liquid crystal layer 15 and in which a color filter or the like is generally formed. . In this case, the liquid crystal display device of the present invention can be realized without substantially changing the process of forming the array substrate.

(Embodiment 3) FIG. 3A is a block diagram showing a liquid crystal display device according to Embodiment 3 of the present invention.

FIG. 3A is different from the first embodiment in that gate signal supply wirings 8a and 8b connected to gate drive circuits 5a and 5b are provided at intermediate points between both ends and the center of gate signal wiring 4, respectively. Are connected to each other, from which power is supplied to both sides of the gate signal wiring 4 so that the scanning signal can be supplied to the liquid crystal display element 1 more evenly to the left and right. Therefore, according to the above configuration, the wiring resistance from the signal supply position to the end of the gate wiring farthest and the capacitance on the wiring can be reduced to half those of the conventional double-sided driving, so that the screen size and the resolution have been further improved. Even in such a case, it is possible to realize a liquid crystal display device having no luminance difference or flicker on the left and right sides of the screen. Note that, as shown in FIG. 3B, even when the source signal drive circuit is a single system, the above-described effect is not changed.

(Embodiment 4) FIG. 4 (a) is a block diagram showing a liquid crystal display device according to Embodiment 3 of the present invention, and FIG. 5 (a) shows source signal supply wiring 9 connected to source signal wiring 2 FIG. 3 is a plan view showing a configuration of a pixel in a portion to be changed.

In FIG. 4A, 1 is a liquid crystal display element,
Reference numeral 4 denotes a gate signal line for supplying a video signal to the liquid crystal display element 1, and reference numerals 5a and 5b denote gate drive circuits connected to the electrode terminals at both ends of the gate signal line 4. The signal wiring 2 is connected to a source signal supply wiring 9 connected to the source drive circuit 3 at the center thereof, and supplies power to both sides of the source signal wiring 2 to supply a video signal to the liquid crystal display element 1 up and down uniformly. .

In the liquid crystal display device configured as described above, since the video signal is supplied to the central portion of each source signal line, the scanning signals can be supplied evenly to the left and right even if one source drive circuit is used. In addition, the wiring resistance and the parasitic capacitance from the signal supply position to the end of the source wiring farthest from the signal supply position can be made the same as in the conventional double-sided driving, so that the luminance difference and flicker at the top and bottom of the screen can be eliminated.

Incidentally, as shown in FIG. 4B, even when the source signal drive circuit is a single system, the above-mentioned effect is not changed.
As shown in FIG. 4C, the cost and the number of steps may be further reduced by combining with a configuration in which the gate signal is supplied to the central portion of the gate wiring. Further, as shown in FIG. 5B, the source signal supply wiring 9 may have an extended shape even after the portion connected to the source signal wiring 2. In this case, the pixel configuration becomes more uniform above and below the connection part,
The occurrence of vertical imbalance can be suppressed.

As shown in FIG. 4D, a source signal supply line 9 extending from the source drive circuit 3 to the source signal line 2
It is also effective to provide the source supply terminal 9c so that two paths can be provided. If the video signal is supplied using only one of these systems, the remaining system is connected to the source supply terminal 9c even if the video supply from this system is broken.
Can be connected to the source drive circuit 3 to supply signals. Although the number of driving circuits increases, signals can be supplied from both ends.

(Embodiment 5) FIG. 5 (c) is a plan view showing one pixel of a liquid crystal display device according to Embodiment 5 of the present invention, and FIGS. 5 (d), 5 (e), and 5 ( f) is the B-
It is B 'sectional drawing.

5C and FIG. 5D are different from the first embodiment in that the source signal supply line 9 is formed below the source signal line 2 via the insulating layer 12b.
This is a point that the connection portion 13b provided in the insulating layer 12b is connected to the source signal wiring 2.

According to the above configuration, the source signal supply wiring 9
And the source signal wiring 2 can be overlapped on the display surface, so that the area shielded by the wiring can be reduced without changing the wiring area of each wiring, thus improving the aperture ratio and obtaining a bright liquid crystal display device. Can be done.

The configuration in which the source signal supply wiring 9 and the source signal wiring 2 are overlapped in the display screen is shown in FIGS.
The configuration is not limited to the configuration shown in FIG.
As shown in (e), the source signal supply wiring 9 and the source signal wiring 2 may be switched between upper and lower layers, and another insulating layer or gate wiring may be provided between the source signal supply wiring 9 and the source signal wiring 2. And other layers for forming wiring. For example, as shown in FIG. 5F, the source signal supply wiring 9 may be formed on a counter substrate 16 which faces the array substrate 14 via the liquid crystal layer 15 and on which a color filter or the like is generally formed. . In this case, the liquid crystal display device of the present invention can be realized without substantially changing the process of forming the array substrate.

(Embodiment 6) FIG. 6A is a block diagram showing a liquid crystal display device according to Embodiment 4 of the present invention.

FIG. 6A is different from the fourth embodiment in that the source signal supply lines 9a and 9b connected to the gate drive circuits 3a and 3b are provided at intermediate points between both ends and the center of the source signal line 2. Are connected to each other, from which power is supplied to both sides of the source signal wiring 2 so that the video signal can be further uniformly supplied to the liquid crystal display element 1 in the vertical direction. Therefore, according to the above configuration, the wiring resistance and the parasitic capacitance from the signal supply position to the farthest source wiring end can be reduced to half that of the conventional double-sided driving. Therefore, even when the screen size and the resolution are further improved. It is possible to realize a liquid crystal display device having no luminance difference and flicker at the top and bottom of the screen. Note that, as shown in FIG. 6B, even when the source signal driving circuit is a single system, the above-described effect is not changed. Further, as shown in FIG. 6C, a combination with a configuration in which a gate signal is supplied to a central portion of a gate wiring may be employed. In this case, display performance can be further homogenized.

[0040]

As described above, according to the present invention, the scanning signal supplied from the gate drive circuit is applied to the center of the gate signal wiring, thereby reducing the number of gate drive circuits to one system. In addition, by configuring the scanning signal supplied from the gate driving circuit in the both-side driving of the gate to be applied to the intermediate point between both ends and the center of the gate signal wiring, the wiring resistance and the parasitic capacitance are conventionally reduced. Therefore, it is possible to obtain a liquid crystal panel with almost no luminance difference between left and right and generation of flicker.

Further, by configuring the video signal supplied from the source drive circuit to be applied to the central portion of the source signal wiring, the number of source drive circuits can be reduced to one system. By configuring so that the scanning signal supplied from the source drive circuit is applied to the midpoint between both ends and the center of the source signal wiring, the wiring resistance and the parasitic capacitance can be reduced to half of the conventional one, A liquid crystal panel with almost no luminance difference and no flicker can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a liquid crystal display device of Embodiment 1.

FIG. 2 is a schematic plan view illustrating a shape of a pixel portion of the liquid crystal display device in Embodiment 1.

FIG. 3 is a block diagram illustrating a liquid crystal display device of Embodiment 3.

FIG. 4 is a block diagram illustrating a liquid crystal display device of Embodiment 4.

FIG. 5 is a schematic plan view illustrating a shape of a pixel portion of a liquid crystal display device in Embodiment 4.

FIG. 6 is a block diagram illustrating a liquid crystal display device of Embodiment 6.

FIG. 7 is a block diagram showing a conventional liquid crystal display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal display element 2 Source signal wiring 3a Source drive circuit 3b Source drive circuit 4 Gate signal wiring 5 Gate drive circuit 6 Controller 7 Flat cable 8 Gate signal supply wiring 101 Pixel

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09G 3/36 G02F 1/136 500 H01L 29/786 H01L 29/78 612C (72) Inventor Katsuhiko Kumakawa Osaka 1006 Kadoma, Kadoma Matsushita Electric Industrial Co., Ltd.F-term (reference) AF51 BC03 BC06 BC11 BC20 BC22 BC23 BF34 BF50 EA03 EC05 FA22 FA23 FA37 5C080 AA10 BB05 CC03 DD05 DD06 FF09 GG05 GG07 JJ02 JJ03 JJ06 KK02 KK43 5F110 BB01 CC07 DD02 EE03 EE14 EE37 NN72

Claims (12)

[Claims] 1. A source signal line and a gate signal line, and a source signal line and a gate disposed in a matrix on two opposing transparent substrates sandwiching a liquid crystal layer therebetween. A switching element provided corresponding to each intersection of the signal wiring, a pixel electrode connected to the switching element, a counter electrode formed on the substrate or the other substrate so as to face the pixel electrode, and the gate In a liquid crystal display device having at least a gate drive circuit for sequentially supplying a scanning signal to a signal line and a source drive circuit for supplying a video signal to the source signal line, a scanning signal supplied from the gate drive circuit is supplied to the gate signal line. The liquid crystal display device is applied to a center side from both ends of the liquid crystal display. 2. The liquid crystal display device according to claim 1, wherein two or more paths are provided from said gate drive circuit to a supply portion of said gate wiring. 3. The liquid crystal display device according to claim 1, wherein a scanning signal supplied from said gate driving circuit is applied to a central portion of said gate signal line. 4. A source signal line and a gate signal line, and a source signal line and a gate arranged in a matrix on two opposing transparent substrates sandwiching a liquid crystal layer therebetween. A switching element provided corresponding to each intersection of the signal wiring, a pixel electrode connected to the switching element, a counter electrode formed on the substrate or the other substrate so as to face the pixel electrode, and the gate In a liquid crystal display device including at least a gate drive circuit for sequentially supplying a scanning signal from both sides to a signal wiring at the same timing and a source driving circuit for supplying a video signal to the source signal wiring, scanning supplied from the gate driving circuit A liquid crystal display device wherein a signal is applied to a center side from both ends. 5. The liquid crystal display device according to claim 4, wherein each scanning signal supplied from said gate drive circuit is applied to an intermediate point between an end and a center of said gate signal wiring. 6. A connection in which a gate signal supply line for supplying each scanning signal from the gate drive circuit is formed below or above the gate signal line via an insulating layer, and is connected to the gate signal line. The liquid crystal display device according to any one of claims 1 to 5, further comprising a unit. 7. A source signal line and a gate signal line, and a source signal line and a gate signal line arranged in a matrix on two opposing transparent substrates sandwiching a liquid crystal layer therebetween. A switching element provided corresponding to each intersection of the signal wiring, a pixel electrode connected to the switching element, a counter electrode formed on the substrate or the other substrate so as to face the pixel electrode, and the gate In a liquid crystal display device comprising at least a gate drive circuit for sequentially supplying a scanning signal to a signal line and a source drive circuit for supplying a video signal to the source signal line, the video signal supplied from the source drive circuit is supplied to the source signal line The liquid crystal display device is applied to a center side from both ends of the liquid crystal display. 8. The liquid crystal display device according to claim 7, wherein two or more paths are provided from said source drive circuit to a supply portion of said source wiring. 9. The liquid crystal display device according to claim 7, wherein a video signal supplied from said source drive circuit is applied to a central portion of said source signal line. 10. A source signal line and a gate signal line, and a source signal line and a gate disposed in a matrix on two opposing transparent substrates sandwiching a liquid crystal layer therebetween. A switching element provided corresponding to each intersection of the signal wiring, a pixel electrode connected to the switching element, a counter electrode formed on the substrate or the other substrate so as to face the pixel electrode, and the gate In a liquid crystal display device having at least a gate drive circuit for sequentially supplying a scan signal to a signal line and a source drive circuit for supplying a video signal from both sides to the source signal line at the same timing, scanning supplied from the gate drive circuit A liquid crystal display device wherein a signal is applied to a center side from both ends. 11. The liquid crystal display device according to claim 10, wherein each video signal supplied from said source driving circuit is applied to an intermediate point between an end and a center of said source signal wiring. 12. A connection in which a source signal supply line for supplying each scanning signal from the source drive circuit is formed below or above the source signal line via an insulating layer, and is connected to the source signal line. The liquid crystal display device according to any one of claims 7 to 11, further comprising a unit.