JP2000275607A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a defective display such as flickerings and burning from occurring by making a potential recovering within a horizontal scanning cycle be close to an optimal common potential, concerning a facing common potential distorted by a source-common coupling. SOLUTION: A pixel array 12 is prevented from flickering and burning in the display by arranging transfer dotting points 15 for bringing a TFT substrate into conduction with a facing substrate only on a gate terminal side 13 of the pixel array 12, and making distribution of the common potential at the time of having recovered from the distortion caused by the coupling between the source electrode and the common electrode within a horizontal scanning cycle be close to an optimal common potential distribution, for the common potential supplied from a common power source 16 via the transfer dotting points 15.

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 device, and more particularly to an arrangement of transfer dots provided for the purpose of conducting a TFT substrate and a common substrate.

[0002]

2. Description of the Related Art FIG. 7 is a diagram showing an equivalent circuit of a conventional active matrix type liquid crystal display device. In the figure, 1 is a thin film transistor (hereinafter referred to as TFT), 2 is a gate electrode of the TFT 1, 3 is a scanning line to which the gate electrode 2 is connected, 4 is a source electrode of the TFT 1, and 5 is a source electrode.
Is connected and a signal line to which a video signal is supplied, and 6 is a TFT
A pixel electrode 7 to which one drain electrode is connected, 7 is a counter common electrode, and a liquid crystal capacitor 8 is formed between the pixel electrode 6 and the common electrode.
Reference numeral 9 denotes a Cs electrode which forms an auxiliary capacitor 10 between the pixel electrode 6 and the Cs electrode. 1, 6 to 10 form one pixel, and the pixels are arranged in a matrix to form a pixel array as a display unit. Here, 1 to 6 are formed on a TFT substrate which is a first substrate, and the common electrode 7 is formed on a counter substrate which is a second substrate. The pixel array is driven by dot inversion.

In the conventional active matrix type liquid crystal display device configured as described above, the scanning line 3 is provided with a TF.
Selection pulse signal V for selectively turning on T1
g is input, the video signal Vs is input to the signal line 5,
The opposing common potential Vcom and the auxiliary potential Vcs are input to the opposing common electrode 7 and the Cs electrode 9, respectively, and liquid crystal display is performed. In the prior art, the transfer common points for conducting the TFT substrate and the opposing substrate are arranged uniformly and as much as possible so that the opposing common potential Vco
m, the opposing common potential, which is mainly distorted by source-common coupling, is restored to a predetermined potential within a horizontal scanning cycle at an arbitrary location in the panel. The opposite common electrode is generally made of ITO (Indium T
in Oxide), and the sheet resistance is about 20Ω. In addition, the counter common electrode is a TFT via a liquid crystal.
A capacitance is formed with the substrate, and the capacitance of the entire panel is about 1
00n [F].

[0004]

In this case, the optimum common potential in the panel increases from the start to the end of the gate in proportion to the delay of the gate potential. Only the optimum common potential and the opposing common potential Vcom did not match. As a result, in a region of the panel that did not match the optimum common potential, flicker and crackling were remarkably recognized. This becomes a serious problem particularly as the definition and size of the panel are increased and the distribution of the delay of the gate potential is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and the opposite common potential which is distorted by the source-common coupling is changed to the optimum common potential which is recovered within a horizontal scanning cycle. A first object is to make the display approach closer and to prevent display defects such as flicker and crackling. A second object of the present invention is to reduce the number of transfer hitting points, thereby reducing the cost of the transfer hitting material and improving the tact time in the transfer hitting step.

[0006]

In a liquid crystal display device according to the present invention, a scanning line provided on a first substrate and supplied with a scanning signal from a gate terminal is disposed so as to intersect the scanning line. A signal line to which a video signal is supplied,
A display portion formed by a plurality of pixels each including a thin film transistor in which a gate electrode is connected to a scanning line and a source electrode is connected to a signal line; and a first substrate which is arranged only on a gate terminal side of the display portion. And a transfer electrode formed so as to conduct the second substrate, a common electrode that supplies a common potential to form a pixel, and a common power supply that supplies a common potential to the transfer dot. The common potential supplied to the common electrode on the gate terminal side is supplied so that the common potential when the common potential is recovered within the horizontal scanning cycle from the distortion due to the coupling between the source electrode and the common electrode becomes the optimum common potential.

A scanning line provided on the first substrate and supplied with a scanning signal from a gate terminal; a signal line arranged to cross the scanning line and supplied with a video signal;
A display portion formed by a number of pixels each including a thin film transistor in which a gate electrode is connected to a scanning line and a source electrode is connected to a signal line; and a first portion is disposed only on a side opposite to a gate terminal of the display portion. A transfer hit point formed to conduct the substrate and the second substrate,
A common potential is supplied by the transfer point, and a common electrode that constitutes a pixel and a common power supply that supplies a common potential to the transfer point are provided.
The common potential supplied to the common electrode on the opposite side of the gate terminal is supplied so that the common potential when recovered within the horizontal scanning cycle from the distortion due to the coupling between the source electrode and the common electrode becomes the optimum common potential. . A variable resistor is connected between the common power supply and the transfer point.

Further, a scanning line provided on the first substrate and supplied with a scanning signal from a gate terminal, a signal line arranged to intersect the scanning line and supplied with a video signal, A display portion formed by a number of pixels each including a thin film transistor having a gate electrode connected thereto and a source electrode connected to a signal line, and disposed only on the gate terminal side and the opposite side of the display portion, the first A transfer hit point formed so as to conduct the substrate and the second substrate, a common electrode which is supplied with a common potential by the transfer hit point and constitutes a pixel, and a common potential is supplied via a variable resistor for each transfer hit point A common power supply is provided, and the variable resistor is connected to a common power supply that recovers within the horizontal scanning period from distortion caused by coupling between the source electrode and the common electrode. It is intended to be adjusted to approximate the distribution to the distribution of the optimum common potential.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a diagram showing an equivalent circuit of an active matrix type liquid crystal display device according to Embodiment 1 of the present invention. In the figure, reference numeral 12 denotes a pixel array serving as a display unit; 13, a gate terminal side of the pixel array 1 where the gate terminal is provided; 14, a source terminal side of the pixel array 12 where the source terminal is provided;
Reference numeral denotes a transfer hit point which is provided so as to establish conduction between the TFT substrate and the opposing substrate and supplies a counter common potential. Reference numeral 16 denotes a common power supply which supplies the transfer hit point 15 with an opposing common potential.

FIG. 2 is a diagram showing an optimum common potential and an opposite common potential of the active matrix type liquid crystal display device according to the first embodiment of the present invention. Embodiment 1
The configuration of one pixel is the same as that shown in FIG. In the liquid crystal display device thus configured, the transfer hit point 15 is provided on the gate terminal side 13, and the common potential supplied from the common power supply 16 is supplied to the opposite substrate via the transfer hit point 15. Embodiment 1
Is applied when the distortion of the opposite common potential due to the source-common coupling is in the positive direction. The common potential Vcom1 output from the common power supply 16 is made to match the optimum common potential value at the gate start end. The number and positions of transfer hit points need to be optimized so as to match the optimum common potential distribution.

In the first embodiment, the transfer hit point 15
2, the delay of the common potential is increased from the transfer hitting point arrangement side (gate start end side) to the non-hitting point arrangement side (gate end side) as shown in FIG. -The potential at which the opposite common potential distorted in the positive direction due to the coupling between the commons recovers within the horizontal scanning period TH approaches the optimum common potential.
This prevents display defects such as flicker and cracking, and further reduces the number of transfer dots by forming a non-dot arrangement portion, thereby reducing the cost of the transfer dot material and improving the tact time in the transfer dot process. it can.

Embodiment 2 FIG. FIG. 3 is a diagram showing an equivalent circuit of an active matrix type liquid crystal display device according to a second embodiment of the present invention, in which transfer dots are provided on the side opposite to the gate terminal side. In the figure, 12-
16 is the same as that in FIG. FIG.
FIG. 9 is a diagram showing an optimum common potential and a counter common potential of an active matrix type liquid crystal display device according to a second embodiment of the present invention.

The second embodiment is applied to a case where the distortion of the opposite common potential due to the source-common coupling is in the negative direction. Common potential V output by common power supply 16
com2 is made to coincide with the optimum common potential value at the gate terminal. The number and positions of transfer hit points need to be optimized so as to match the optimum common potential distribution. In the second embodiment, the transfer point 15 is set to the gate terminal side 1
3, the delay of the common potential is increased from the start end of the transfer gate to the end of the gate as shown in FIG. 4, and the opposite common potential distorted by the coupling between the source and the common is scanned horizontally. The potential recovered within the period TH is made to approach the optimum common potential. This prevents display defects such as flicker and crackling,
Further, the formation of the non-stripping point portion to reduce the number of transfer striking points leads to a reduction in the cost of the transfer striking material and an improvement in tact in the transfer striking step.

Embodiment 3 FIG. 5 is a diagram showing an equivalent circuit of an active matrix type liquid crystal display device according to Embodiment 3 of the present invention. In the figure, reference numerals 12 to 16 are the same as those in FIG. Reference numeral 17 denotes a variable resistor inserted in series between the common power supply 16 and the transfer point 15. The transfer hit point 15 is provided on the gate terminal side 13. In the third embodiment, the source
This is applied when it is necessary to adjust the distribution of the delay of the common potential when the distortion of the opposite common potential due to the coupling between the commons is in the positive direction. The common potential output from the common power supply 16 is matched with the optimum common potential value at the gate start end. If the common common potential does not approach the optimum common potential distribution only by the transfer hit point arrangement, adjust the variable resistance value and change the delay of the input common potential to the panel to change the common common potential to the optimum common potential distribution. Get closer. This configuration is also applicable when the transfer point 15 is provided on the side opposite to the gate terminal side 13.

Embodiment 4 FIG. 6 is a diagram showing an equivalent circuit of an active matrix type liquid crystal display device according to Embodiment 4 of the present invention. In the figure, reference numerals 12 to 17 are the same as those in FIG. In FIG. 6, variable resistors 17 are inserted in series between the common power supply 16 and each transfer point 15. The transfer hit points 15 are provided on the gate terminal side 13 and the opposite side. Embodiment 4 can be applied to both cases where the distortion of the opposing common potential due to source-common coupling is positive and negative. For example, when the distortion of the opposite common potential is positive, the variable resistance values R1, R2 <R3,
By stopping the supply of charges to the side opposite to the gate terminal side 13 as R4, the same effect as in the first embodiment can be expected.

[0016]

Since the present invention is configured as described above, it has the following effects. A scanning line provided on the first substrate and supplied with a scanning signal from a gate terminal, a signal line arranged to intersect the scanning line, and supplied with a video signal, and a gate electrode connected to the scanning line A display portion formed by a number of pixels each including a thin film transistor having a source electrode connected to a signal line, and a display portion formed only on the gate terminal side of the display portion,
A transfer hit point formed so as to conduct the first substrate and the second substrate, a common electrode which is supplied with a common potential by this transfer hit point and forms a pixel, and a common power supply which supplies a common potential to the transfer hit point The common power supply supplies the common potential supplied to the common electrode on the gate terminal side such that the common potential when the common potential is recovered within the horizontal scanning period from the distortion due to the coupling between the source electrode and the common electrode becomes the optimum common potential. So
The distribution of the common potential having the distortion in the positive direction can be approximated to the distribution of the optimum common potential, and the number of transfer points can be reduced to reduce the cost.

A scanning line provided on the first substrate and supplied with a scanning signal from a gate terminal; a signal line arranged to intersect the scanning line and supplied with a video signal;
A display portion formed by a number of pixels each including a thin film transistor in which a gate electrode is connected to a scanning line and a source electrode is connected to a signal line; and a first portion is disposed only on a side opposite to a gate terminal of the display portion. A transfer hit point formed to conduct the substrate and the second substrate,
A common potential is supplied by the transfer point, and a common electrode that constitutes a pixel and a common power supply that supplies a common potential to the transfer point are provided.
Since the common potential supplied to the common electrode on the opposite side of the gate terminal is supplied so that the common potential at the time of recovery within the horizontal scanning period from the distortion due to the coupling between the source electrode and the common electrode becomes the optimum common potential, The distribution of the common potential having directional distortion can be made closer to the optimum common potential distribution, and the number of transfer points can be reduced to reduce costs.

Further, since a variable resistor is connected between the common power supply and the transfer hit point, the distribution of the common potential supplied by the common power supply can be better and approximated to the optimum common potential distribution.

Further, a scanning line provided on the first substrate and supplied with a scanning signal from a gate terminal, a signal line arranged to intersect with the scanning line and supplied with a video signal, A display portion formed by a number of pixels each including a thin film transistor having a gate electrode connected thereto and a source electrode connected to a signal line, and disposed only on the gate terminal side and the opposite side of the display portion, the first A transfer hit point formed so as to conduct the substrate and the second substrate, a common electrode which is supplied with a common potential by the transfer hit point and constitutes a pixel, and a common potential is supplied via a variable resistor for each transfer hit point A common power supply is provided, and the variable resistor is connected to a common power supply that recovers within the horizontal scanning period from distortion caused by coupling between the source electrode and the common electrode. Since is adjusted so as to approach the distribution to the distribution of the optimum common potential may correspond to the common potential with the distortion of the positive and negative directions.

[Brief description of the drawings]

FIG. 1 is a diagram showing an equivalent circuit of an active matrix liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an optimum common potential and an opposite common potential of the active matrix type liquid crystal display device according to the first embodiment of the present invention.

FIG. 3 is a diagram showing an equivalent circuit of an active matrix liquid crystal display device according to a second embodiment of the present invention.

FIG. 4 is a diagram showing an optimum common potential and an opposite common potential of an active matrix liquid crystal display device according to a second embodiment of the present invention.

FIG. 5 is a diagram showing an equivalent circuit of an active matrix liquid crystal display device according to a third embodiment of the present invention.

FIG. 6 is a diagram showing an equivalent circuit of an active matrix liquid crystal display device according to a fourth embodiment of the present invention.

FIG. 7 is a diagram showing an equivalent circuit of a conventional active matrix type liquid crystal display device.

[Explanation of symbols]

1 thin film transistor, 2 gate electrode, 3 scanning line, 4 source electrode, 5 signal line, 6 pixel electrode,
7 counter common electrode, 8 liquid crystal capacitor, 9 Cs electrode,
10 auxiliary capacitance, 12 pixel array, 13 gate terminal side, 14 source terminal side, 15 transfer hit point, 16 common power supply, 17 variable resistance.

Claims (4)

[Claims] 1. A liquid crystal display device having a liquid crystal sandwiched between a first substrate and a second substrate disposed opposite to the first substrate, wherein the liquid crystal display device is provided on the first substrate, A scanning line to which a scanning signal is supplied from a gate terminal, a signal line which is arranged to intersect the scanning line and is supplied with a video signal,
A display portion formed by a plurality of pixels each including a thin film transistor having a gate electrode connected to the scanning line and a source electrode connected to the signal line, and arranged only on the gate terminal side of the display portion; A transfer hit point formed so as to conduct the substrate and the second substrate, a common electrode which is supplied with a common potential by the transfer hit point and constitutes a pixel, and a common power supply which supplies a common potential to the transfer hit point. Is characterized in that the common potential supplied to the common electrode on the gate terminal side is supplied so that the common potential when recovered within the horizontal scanning cycle from the distortion due to the coupling between the source electrode and the common electrode becomes the optimum common potential. Liquid crystal display device. 2. A liquid crystal display device having a liquid crystal sandwiched between a first substrate and a second substrate disposed to face the first substrate, wherein the liquid crystal display device is provided on the first substrate. A scanning line to which a scanning signal is supplied from a gate terminal, a signal line which is arranged to intersect the scanning line and is supplied with a video signal,
A display portion formed by a number of pixels each including a thin film transistor having a gate electrode connected to the scanning line and a source electrode connected to the signal line, and arranged only on the opposite side of the gate terminal of the display portion, A transfer hit point formed so as to conduct the first substrate and the second substrate, a common electrode which is supplied with a common potential by the transfer hit point and constitutes a pixel, and a common power supply which supplies a common potential to the transfer hit point. The common power supply supplies the common potential supplied to the common electrode on the opposite side of the gate terminal so that the common potential at the time of recovery within the horizontal scanning cycle from the distortion due to the coupling between the source electrode and the common electrode becomes the optimum common potential A liquid crystal display device comprising: 3. The liquid crystal display device according to claim 1, wherein a variable resistor is connected between the common power supply and the transfer hit point. 4. A liquid crystal display device having a liquid crystal sandwiched between a first substrate and a second substrate disposed opposite to the first substrate, wherein the liquid crystal display device is provided on the first substrate. A scanning line to which a scanning signal is supplied from a gate terminal, a signal line which is arranged to intersect the scanning line and is supplied with a video signal,
A display portion formed by a number of pixels each including a thin film transistor having a gate electrode connected to the scanning line and a source electrode connected to the signal line, and arranged only on the gate terminal side of the display portion and on the opposite side thereof. A transfer hit point formed so as to conduct the first substrate and the second substrate, a common electrode supplied with a common potential by the transfer hit point and constituting a pixel, and a common potential via a variable resistor for each transfer hit point. And the variable resistor is adjusted so that the distribution of the common potential recovered within the horizontal scanning period from the distortion due to the coupling between the source electrode and the common electrode approaches the optimum common potential distribution. Characteristic liquid crystal display device.