JP2000330518A - Active matrix type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce vertical stripe shaped display unevenness in an active matrix type liquid crystal display device in which a horizontal scanning driving circuit and a vertical scanning driving circuit are integrally formed on a glass substrate. SOLUTION: This display produces the inversion signal of a waveform distortion by a detecting electrode 8 detecting the waveform distortion and a correcting circuit 9 formed in the outside of a panel or in the inside of the panel and makes the inversion signal cancel the waveform distortion to a counter electrode 10 as to the vertical stripe shaped display unevenness which is generated by the effect of the waveform distortion generated at the time of the rising and the falling of a clock line 6 which operates a horizontal scanning driving circuit 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix type liquid crystal display device.
The present invention relates to a driving technique of an active matrix type liquid crystal display device driven in a point sequential manner.

[0002]

2. Description of the Related Art FIG. 5 shows a general configuration of a conventional active matrix type liquid crystal display device. Hereinafter, the active matrix type liquid crystal display device will be described with reference to FIG.

The active matrix type liquid crystal display device comprises a plurality of gate lines X arranged in rows, a plurality of data lines Y arranged in columns, and a plurality of pixel transistors 54 provided at respective intersections of the two. The pixel transistor 54 is formed of, for example, a liquid crystal cell and forms the display area 51. The pixel transistor 54 is formed by integrally forming a thin film transistor for driving the pixel transistor 54.

FIG. 5 shows a case where there are 320 horizontal pixels.

The vertical scanning drive circuit 53 sequentially scans each gate line X and selects one row of pixel transistors 54 every one horizontal period. Further, the horizontal scanning drive circuit 52
Scans each data line Y sequentially within one horizontal period, samples the video signal Vsig, and writes it in the selected row of pixel transistors 54 in dot sequence. In particular,
Source lines Y1 to Y which are data lines Y
Reference numeral 320 is connected to the data line 57 connected to each of the source lines Y1 to Y320 via the transfer gate 58, and receives an external supply of the video signal Vsig.
The horizontal scanning drive circuit 52 sequentially outputs sampling pulses, sequentially drives the transfer gates 58 to open and close, samples the video signal Vsig to the source lines Y1 to Y320, and applies the voltages Vs1 to Vs320.

A clock signal CLK for operating the horizontal scanning drive circuit 52 is input to the horizontal scanning drive circuit 52, and a clock line 56 is drawn. At this time, the clock signal frequency is a frequency obtained by dividing one horizontal scanning period by the number of source lines except for a blanking period.
about z. Further, each pixel transistor 54 is connected to a counter electrode 59 via a liquid crystal capacitor 55, and a voltage of data supplied from a data line 57 and a voltage of the counter electrode 59.
Is written into the liquid crystal capacitance 55.

[0007]

However, in the case of the above-described active matrix type liquid crystal display device, vertical stripe-shaped display unevenness 83 occurs in the source line Y direction of the active matrix type liquid crystal display device 81 as shown in FIG.
Reference numeral 82 denotes a flexible terminal. The cause will be described with reference to FIGS.

FIG. 6 shows a part of a conventional active matrix type liquid crystal display device as an equivalent circuit of a distributed constant circuit. Here, reference numeral 61 denotes a clock line (5 in FIG. 5).
6) and 62 are liquid crystal capacitors (55 in FIG. 5), and 63 is a counter electrode (59 in FIG. 5). Clock line 6
1 receives the clock signal CLK, the liquid crystal capacitor 6
2, a waveform distortion occurs in the counter electrode 63 in synchronization with the rise and fall of the clock signal CLK.

These operations will be described in more detail with reference to the timing chart of FIG. First, the CLK input waveform (70) in the liquid crystal capacitor 62 shown in FIG.
1). Further, in the counter electrode 63 shown in FIG.
Distortion like the waveform (72) occurs. Usually, the counter electrode covers the entire panel with a solid pattern formed on the other glass substrate that faces the glass substrate on which the pixel pattern is placed via a liquid crystal capacitor. The resulting distortion is superimposed on the data signal as it is,
Even when a certain data signal is input, a distorted waveform like the Vs57 waveform (73) is actually written to the data line Y. Therefore, the voltage of V1 or V2 in FIG. 7 is applied to the liquid crystal, and the difference ΔV between V1 and V2 causes uneven display. Since the display unevenness occurs in synchronization with the clock signal CLK, when a solid screen or the like is displayed, vertical stripe-shaped display unevenness 83
Appears as.

An object of the present invention is to provide an active matrix type liquid crystal display device in which vertical stripe-like display unevenness is reduced by changing the above-mentioned conventional circuit configuration.

[0011]

In order to achieve the above object, the present invention provides an active matrix type liquid crystal driving device comprising a plurality of gate lines arranged in rows and a plurality of source lines arranged in columns. A plurality of pixels provided at each intersection of the two and constituting a display area; a vertical scanning drive circuit for sequentially scanning each gate line vertically and selecting one row of pixels every one horizontal period; A horizontal scanning drive circuit for sequentially scanning each source line within the horizontal period, sampling a video signal, and writing dot-sequentially to selected one row of pixels, and comprising a vertical scanning drive circuit and a horizontal scanning drive circuit. Are formed on the same first glass substrate. Also, the first
A counter electrode present on the second glass substrate via the glass substrate and the liquid crystal material, and a detection electrode for detecting a waveform distortion generated in the counter electrode by a clock signal for driving the horizontal scanning drive circuit. And an inverting amplifier for inverting the polarity of the waveform distortion obtained at the detection electrode and superimposing the inverted waveform on the counter electrode.

According to the present invention, an effect is obtained that an inverted signal of waveform distortion is generated, and distortion to the counter electrode is canceled to prevent the occurrence of vertical stripe-shaped display unevenness appearing in the source line direction.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

(Embodiment 1) FIG. 1 is a circuit configuration diagram of an active matrix type liquid crystal display device according to Embodiment 1 of the present invention. Here, the configuration of the horizontal scanning drive circuit 2, the vertical scanning drive circuit 3, and the pixels in the first embodiment,
The operation thereof is not different from the conventional circuit configuration shown in FIG. 5, but will be described with reference to the change of symbols. 1 is a display area, 4 is a pixel transistor, 5 is a liquid crystal capacitor, 6 is a clock line, and 7 is a data line. It is.

In FIG. 1, a clock signal CLK for operating the horizontal scanning drive circuit 2 is input from the outside, and is input to the horizontal scanning drive circuit 2 through a clock line 6.

A detection electrode 8 is formed on the same glass substrate as the counter electrode 10, and an output terminal of the detection electrode 8 is connected to a correction circuit 9 installed outside the panel. The output terminal of the correction circuit 9 is connected to a counter electrode 10 inside the panel. Here, the correction circuit 9 includes an inverting amplifier 90, and the output terminal of the detection electrode 8 is connected to the negative input terminal of the inverting amplifier 90. The common terminal COM is connected to the positive input terminal.

Next, the circuit operation of the active matrix type liquid crystal display device will be described with reference to the timing chart of FIG.

When the clock signal CLK is input (input waveform 20), the clock line 6 has a waveform (2) due to the resistance component of the clock line and the liquid crystal capacitance component.
The waveform rounding of 1) occurs. Further, the detection electrode 8
In synchronization with the rise and fall of the input, CLK →
Waveform distortion (22) occurs in the direction indicated by the detection electrode 8.

Next, since the correction circuit 9 outputs a waveform (23) obtained by inverting the waveform distortion detected by the detection electrode 8, waveform distortion occurs in the direction indicated by the output of the correction circuit 9. Here, when the data signal Vsig is input from the outside, a distortion is superimposed on the data line 7 in a direction generated by the detection electrode 8 and the output of the correction circuit 9, and the distortion is shown on the detection electrode 8 → Vs 7 respectively. Waveform distortion (24) and the waveform distortion (25) shown in the correction output 9 → Vs7.

However, the waveform of the counter electrode 10 (2
6) is offset by the combination of the respective distortions, so that the data line 7 actually has the respective waveform voltages V1
As a result, only the voltage V as shown in the waveform (27) of Vs7 obtained by synthesizing the waveform voltage V2 is applied, and the counter electrode 10 generated by the influence of the rising and falling of the clock line 6 as in the related art. It is possible to reduce vertical stripe-like display unevenness (83 in FIG. 8) caused by the influence of the distortion on the image.

As shown in FIG. 6 of the prior art,
Since the clock line 6 and the counter electrode 10 in FIG. 1 are represented by a distributed constant circuit, the magnitude of the distortion of the counter electrode 10 caused by the influence of the clock line 6 depends on the position in the display area 1, the liquid crystal capacitance 5, and the like. Therefore, by adjusting the resistances R1 and R2 of the inverting amplifier 90 in the correction circuit 9, it is possible to obtain more optimal display quality.

As described above, by using the circuit configuration of the active matrix type liquid crystal display device shown in the first embodiment of the present invention, the vertical stripe-like display unevenness which has conventionally occurred can be effectively removed, and the display quality can be improved. Thus, it is possible to provide an active matrix type liquid crystal display device.

(Embodiment 2) FIG. 3 is a circuit configuration diagram of an active matrix type liquid crystal display device according to Embodiment 2 of the present invention. Here, the configuration of the horizontal scan drive circuit 32, the vertical scan drive circuit 33, and the pixels in the second embodiment and the operation thereof are not different from those of the conventional circuit configuration. Is a display area, 34 is a pixel transistor, 35 is a liquid crystal capacitor, 3
6 is a clock line and 37 is a data line.

In FIG. 3, a clock signal CLK for operating the horizontal scanning drive circuit 32 is input from the outside, and is input to the horizontal scanning drive circuit 32 through a clock line 36.

A detection electrode 38 is formed on the same glass substrate as the counter electrode 40, and an output terminal of the detection electrode 38 is connected to a correction circuit 39 similarly formed on the same glass substrate. I have. The output terminal of the correction circuit 39 is connected to the counter electrode 40. Here, the correction circuit 3
9 comprises an inverting amplifier 41 and a detection electrode 38.
Is connected to the negative input terminal of the inverting amplifier 41. The common signal COM is connected to the positive input terminal.

Next, the operation of the circuit of the active matrix type liquid crystal display device will be described with reference to the timing chart of FIG.

When the clock signal CLK is input (input waveform 42), the waveform (43) of the CLK 36 is rounded on the clock line 36 due to the resistance component of the clock line and the liquid crystal capacitance component. The detection electrode 38 has CL
In synchronization with the rise and fall of the K input, CLK
→ Waveform distortion (44) occurs in the direction indicated by the detection electrode 38. Next, since the correction circuit 39 outputs a waveform (45) obtained by inverting the waveform distortion detected by the detection electrode 38, the waveform distortion occurs in the direction indicated by the output of the correction circuit 39. Here, when the data signal Vsig is input from the outside, a distortion is superimposed on the data line 37 in a direction generated by the detection electrode 38 and the output of the correction circuit 39, and the distortion is shown on the detection electrode 38 → Vs37, respectively. Waveform distortion (46) and the waveform distortion (47) shown in the correction output 39 → Vs37.

However, the waveform of the counter electrode 40 (4
8) is offset by the combination of the respective distortions, so that the actual waveform voltage V
1 and the waveform Vs7 obtained by combining the waveform voltage V2 (49)
Only the voltage V as shown in FIG. 1 is applied, and as in the prior art, vertical stripe-shaped display unevenness caused by the influence on the counter electrode 40 caused by the rise and fall of the clock signal CLK (see FIG. 8 83) can be reduced.

As shown in FIG. 6 of the prior art,
Since the clock line 36 and the counter electrode 40 in FIG. 3 are represented by a distributed constant circuit, the magnitude of the distortion of the counter electrode 40 caused by the influence of the clock line 36 depends on the position in the display area 31, the liquid crystal capacitance 35, and the like. Therefore, by adjusting the resistances R1 and R2 of the inverting amplifier 41 in the correction circuit 39, it is possible to obtain more optimal display quality.

Further, in the second embodiment, the correction circuit 3
Since 9 is formed on the same glass substrate as the horizontal scan drive circuit 32 and the vertical scan drive circuit 33, there is no need to provide a new external circuit, which is advantageous in terms of cost.

As described above, by using the circuit configuration of the active matrix type liquid crystal display device shown in the embodiment of the present invention, display unevenness in the form of vertical stripes which has conventionally occurred can be effectively removed, and the display quality can be improved. An active matrix display device can be provided.

[0032]

As described above, the present invention uses a simple circuit configuration of a waveform distortion detecting electrode and an inverting amplifier for inverting the polarity of the waveform distortion, thereby canceling the waveform distortion generated in the counter electrode. In addition, it is possible to provide an active matrix type liquid crystal display device which can effectively reduce vertical stripe-like display unevenness and have extremely high display quality as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of an active matrix liquid crystal display device according to Embodiment 1 of the present invention.

FIG. 2 is a timing chart showing an operation of the active matrix liquid crystal display device according to the first embodiment of the present invention.

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

FIG. 4 is a timing chart showing an operation of an active matrix liquid crystal display device according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram of a conventional active matrix type liquid crystal display device.

FIG. 6 is a diagram showing an equivalent circuit of a conventional active matrix type liquid crystal display device.

FIG. 7 is a timing chart showing the operation of a conventional active matrix type liquid crystal display device.

FIG. 8 is a diagram showing display unevenness in the form of vertical stripes in a conventional active matrix type liquid crystal display device.

[Explanation of symbols]

1, 31, 51 Display area of active matrix type liquid crystal display device 2, 32, 52 Horizontal scan drive circuit 3, 33, 53 Vertical scan drive circuit 4, 34, 54 Pixel transistor 5, 35, 55 Liquid crystal capacitance 6, 36, 56 Clock line 7, 37, 57 Data line 9, 39 Correction circuit 10, 40, 59 Counter electrode 41, 90 Inverting amplifier 58 Transfer gate 61 Equivalent circuit of clock line 62 Equivalent circuit of liquid crystal capacitance 63 Equivalent circuit of counter electrode Y1 Y320 Source line X1 to X3 Gate line 81 Active matrix liquid crystal display device 82 Flexible terminal 83 Vertical stripe-shaped display unevenness

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H093 NA16 NA42 NC18 NC58 NC62 ND15 NE03 5C006 AC11 AF46 AF50 AF52 BB16 BC03 BC12 BC20 BF25 BF38 FA18 FA22 5C080 AA10 BB05 DD05 FF11 JJ02 JJ03 JJ04

Claims (3)

[Claims] 1. A plurality of gate lines arranged in a row, a plurality of source lines arranged in a column, a plurality of pixels provided at each intersection of the two and constituting a display area, and A vertical scanning drive circuit for sequentially performing vertical scanning and selecting one row of pixels every one horizontal period, and one row of pixels selected by sequentially scanning each source line within one horizontal period and sampling a video signal An active matrix type liquid crystal display device, comprising: a horizontal scanning drive circuit for writing dot-sequentially to the pixels; wherein the vertical scanning drive circuit and the horizontal scanning drive circuit are formed on the same first glass substrate as the pixels. A second glass layer interposed between the first glass substrate and the liquid crystal material;
A counter electrode formed on the glass substrate, a detection electrode for detecting a waveform distortion generated in the counter electrode by a clock signal for driving the horizontal scanning drive circuit, and a waveform inversion obtained by the detection electrode by inverting the polarity. An active matrix type liquid crystal display device, comprising: a correction circuit for superimposing on the counter electrode. 2. The correction circuit comprises an inverting amplifier, is provided outside a panel made of the first and second glass substrates, and has an output from a detection electrode formed on the second glass substrate. 2. The active matrix type liquid crystal display device according to claim 1, wherein the active matrix type liquid crystal display device is connected to a terminal and an output terminal of the inverting amplifier is connected to a counter electrode formed on the second glass substrate. 3. The active matrix type liquid crystal display device according to claim 1, wherein said correction circuit is formed on said first or second glass substrate.