JPH05232448A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To reduce in-surface brightness unevenness by decreasing a difference depending upon the position of the waveform distortion of a voltage generated under the influence of the impedance of a picture element. CONSTITUTION:A liquid crystal panel 11 is constituted by crossing and arranging plural signal electrodes Xm and plural scanning electrodes Yn across a liquid crystal layer and forming picture elements in matrix, and when a signal voltage and a scanning voltage whose waveforms vary stepwise are applied to one-end sides of the signal electrodes Xm and scanning electrodes Yn of the liquid crystal panel 11 to drive the liquid crystal of the respective picture elements, the waveform of at least one of the scanning voltage and signal voltage applied to the respective electrodes is distorted by a constant quantity. Consequently, the waveform of the liquid crystal driving voltage applied to each of the picture elements in a display area is already distorted. Consequently, the influence of input part resistance and impedance of each picture element is made a little, so variation in the distortion of the voltage waveforms is reduced and the difference in driving voltage effective value due to a difference in picture element position is made small, so the brightness unevenness is reducible.

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,
Specifically, a plurality of signal electrodes and a plurality of scanning electrodes are crossed across the liquid crystal layer to form a matrix of pixels, and a signal voltage and a scanning voltage are applied to one end of each of the signal electrodes and the scanning electrodes. And a liquid crystal display device configured to drive the liquid crystal of each pixel.

[0002]

2. Description of the Related Art Conventionally, a simple matrix type liquid crystal display device in which liquid crystal pixels are arranged in a matrix has been widely adopted, and a drive circuit for driving those liquid crystal pixels is known to have a structure shown in FIG. ing. In FIG. 15, the liquid crystal panel 11 sandwiches a liquid crystal layer, and a plurality of thin film-shaped signal electrodes X and a plurality of scanning electrodes Y are arranged to intersect each other to form a pixel P.
The signal electrode drive circuit 12 and the scan electrode drive circuit 13 apply a signal voltage and a scan voltage to one end of each of the signal electrodes and the scan electrode, respectively.
The liquid crystal panel 11 is formed by using, for example, a twisted nematic liquid crystal, in which the number of signal electrodes m (for example, m = 1920) and the scanning electrodes n (for example, n = 400) are arranged in a grid pattern. The drive circuits 12 and 13 are adapted to directly drive pixels by time division. For details of this driving method, for example, Japanese Patent Publication No. 57-57718, Japanese Patent Application No. 51-112994, and publication "Hitachi L"
CD driver LSI data book (Hitachi, Ltd., published in March 1988) ”.

According to the above publication, the scan electrode driving circuit 1
3 applies a scanning voltage to a plurality of scanning electrodes sequentially from the end in a constant cycle. The signal electrode drive circuit 12 selectively applies a signal voltage to each signal electrode in accordance with the input image data and the scanning. In addition, each of the drive circuits 12 and 13 has a voltage V ₁ of six potential levels output from the power supply circuit 14.
From ~V _6, respectively captures four voltage switches the level of the combined output voltage to the image signal and the scanning signal is applied to each electrode, so as to AC drive the liquid crystal of the pixel. Note that, for the signal electrode drive circuit 12 and the scan electrode drive circuit 13, for example, "LCD driver LSI HD66107T" manufactured by Hitachi, Ltd. can be used, and the details of the operation are described in the above publications.

[0004]

In the liquid crystal display device as described above, the voltage applied to one end of each electrode (hereinafter referred to as the input end) moves away from the input end, so that the resistance of the electrode and the liquid crystal are sandwiched between them. The waveform is distorted by the capacitance formed at the intersection of the electrodes, and the effective value of the voltage applied to the liquid crystal of each pixel changes depending on the position, which causes a difference in brightness depending on the position of the liquid crystal panel, which is called brightness unevenness. There is a problem that occurs.

FIG. 16 shows the phenomenon of occurrence of the uneven brightness.
~ It demonstrates in detail with reference to FIG. FIG. 16 is an electrically equivalent circuit of the liquid crystal panel 11 viewed from the drive circuits 12 and 13, in other words, a load circuit of each drive circuit 12 and 13. For simplicity, the figure shows the scan electrode drive circuit 1
3 shows a load circuit related to the scan electrode Y ₁ of the first line viewed from 3. As shown in the figure, n signal electrodes X _{1 to} Xm intersect the scanning electrode Y ₁ , and a capacitance CL is formed between the electrodes sandwiching the liquid crystal layer at the intersections. Further, the resistances Rx and Ry of the electrodes of the portion corresponding to each pixel are distributed. The resistors Rxi and Ryi are input unit resistors, for example, on-resistances Rx ₁ and Ry ₁ of the switching elements of the drive circuits 12 and 13 and a connection resistance Rx ₂ of the drive circuit and the electrodes, respectively.
It is a combined resistance of Ry ₂ and the resistances Rx ₃ and Ry ₃ of the input terminal portion of each electrode. Therefore, the load circuit of one line of the scan electrode Y ₁ viewed from the scan electrode drive circuit 13 has an input resistance R
It is represented as a ladder circuit composed of xi and Ryi, resistors Rx and Ry of each pixel, and a capacitance CL. It is known that when a voltage that changes stepwise is applied to such a ladder-type circuit, the waveform is distorted as the distance from the application point increases.

An example of this waveform distortion is shown in FIG. The figure shows signal electrodes X ₁ , X ₂ , ..., X (m−1), X.
The signal voltage Vx shown in the diagram (a) is applied to m, the voltage applied to the liquid crystal of each pixel when applying a scan voltage Vy to the scan electrodes Y ₁ shown in FIG. (b) (hereinafter, referred to as a liquid crystal driving voltage ) VLm is shown in FIGS. The display in this case corresponds to a case where all the pixels in the first line have the same display data. As can be seen from the figure, the scanning voltage Vy applied to each pixel has its waveform distorted by the input portion resistance Ryi, the electrode resistance Ry, and the capacitance CL of the liquid crystal, and the liquid crystal drive voltages VL ₁ , VL ₂ , VL ₃ , VL (m-
1) and VLm are shown in FIGS.
As shown in (f) and (g), as the distance from the input terminal of the scanning electrode Y ₁ increases, the waveforms of the rising portion and the falling portion that change stepwise become distorted waveforms. Further, the change in the waveform distortion of the liquid crystal drive voltage shows the same change as the voltage attenuation of the ladder circuit, changes significantly in the pixels near the input terminal portion, and decreases as the distance from the input terminal increases.

Due to the difference in the waveform distortion of the liquid crystal driving voltage depending on the position, the effective value of the liquid crystal driving voltage applied to the liquid crystal of each pixel changes, so that the transmittance of each pixel also changes depending on the position. This causes uneven brightness.

Here, FIGS. 18A and 18B show the simulation results of the change in the effective value of the liquid crystal drive voltage depending on the pixel position and the change in the transmittance depending on the pixel position, respectively.
In the simulation, the effective value of the liquid crystal drive voltage waveform of each pixel is obtained by setting the resistance and the capacitance of an actual liquid crystal panel and applying the voltage value of the drive condition to the equivalent circuit of FIG. The horizontal axis in the figures represents a pixel position m from the input terminal of the first line scan voltage of the scan electrodes Y _1, the vertical axis 60 line of signal electrodes on the scanning electrode Y ₁ in FIG. (A) Relative value (%) of the liquid crystal drive voltage of each pixel, with the effective value of the liquid crystal drive voltage VL ₆₀ of the X ₆₀ pixel being 100.
The vertical axis of FIG. 7B shows the transmittance of each pixel as a relative value (%) with the transmittance of the pixel of the signal electrode X ₆₀ of the 60th line on the scanning electrode Y ₁ being 100. Is.

As is clear from the result shown in FIG.
The relative value of the effective value of the liquid crystal drive voltage applied to the liquid crystal of each pixel is attenuated as the distance from the input terminal of the scan electrode Y ₁ increases. In particular, the change is large in the range up to about 1000 lines, and the change becomes more severe as it approaches the input terminal. By the way, the transmittance TR of the liquid crystal of each pixel increases almost proportionally from a certain voltage to the effective value VR of the liquid crystal drive voltage as shown in FIG. 19 (region A in the figure), and becomes saturated when the voltage exceeds a certain voltage. (Shown as region B) is shown. It is the change region A that mainly affects the luminance characteristics. Therefore, as shown in FIG. 18B, the transmittance is also attenuated as the distance from the input terminal of the scanning electrode Y ₁ is increased, and is significantly changed in the range up to about 1000 lines, which causes uneven brightness in the surface. Of.

The luminance unevenness due to the above causes is disclosed in Japanese Patent Laid-Open No. 1-22.
As described in Japanese Patent No. 13623, when the drive voltage is applied from both ends of each electrode, there is not much problem. However, this method complicates the production and raises the cost.

It is also possible to change the voltage level of the signal electrode according to the position of the scanning electrode in order to reduce the uneven brightness due to the above causes, but the structure of the drive circuit becomes complicated and the cost increases. There is.

It is an object of the present invention to reduce the in-plane luminance unevenness without changing the levels of the signal voltage and scanning voltage applied to each electrode and applying those voltages to one end of each electrode. It is to provide a high quality liquid crystal display device.

[0013]

In order to achieve the above object, the present invention provides a liquid crystal in which a plurality of signal electrodes and a plurality of scanning electrodes are crossed across a liquid crystal layer to form a matrix of pixels. A panel, and a signal electrode drive circuit and a scan electrode drive circuit for driving the liquid crystal of each pixel by applying a signal voltage and a scan voltage having a waveform that changes stepwise to one end of each of the signal electrode and the scan electrode of the liquid crystal panel. And a means for distorting a waveform of at least one of the scanning voltage and the signal voltage applied to each electrode.

As a means for distorting the waveform of the signal voltage or the scanning voltage, an impedance element or a resistance element is preferable, but a means including an arithmetic means may be used.

As the impedance element, it is possible to use a dummy pixel formed by arranging the electrode and the other electrode across the liquid crystal layer on the input side of the electrode corresponding to the voltage that distorts the waveform. .. In this case, the dummy pixel can be integrally formed in the non-display area outside the display area of the liquid crystal display panel. Furthermore, it is possible to equip the electrode drive circuit as an integrated circuit equivalently or to form a combination thereof.

When the impedance element is formed by using a dummy pixel, it is preferable that the dummy pixel has a structure invisible from the outside.

[0017]

According to the present invention having the above-mentioned structure, the above object can be achieved by the following operation. As described with reference to FIG. 18, since the electrical equivalent circuit of the liquid crystal panel viewed from the electrode driving circuit is a ladder type circuit, the distortion of the voltage waveform changes from the input end to a certain range, that is, the difference in distortion depending on the position. Is big. However, beyond the range, if the distance from the input end exceeds a certain level, the distortion itself is large, but the difference due to the position is small. The distortion of the voltage waveform is caused by suppressing the rising and falling changes of the step change of the signal voltage or the scanning voltage by the impedance element including the resistance and the capacitance of each pixel. Therefore, if the waveform of the rising and falling changes of the voltage input to each electrode is distorted in advance into a waveform that changes relatively smoothly, the effect of suppressing the change due to the impedance element of each pixel becomes small, so that It is possible to reduce the relative ratio between the effective value of the liquid crystal drive voltage of the pixel near the input end and the effective value of the liquid crystal drive voltage of the pixel at the position away from the input end.

The present invention is based on such an action, and is provided with means for predistorting at least one of the signal voltage and the scanning voltage. As a result, the difference in the waveform distortion of the drive voltage due to the difference in the position of the pixel in the direction of the signal electrode or the scan electrode is reduced, and the difference in the effective value of the liquid crystal drive voltage applied to the liquid crystal of each pixel is reduced. As a result, the difference in liquid crystal transmittance of the pixel due to the difference in position is suppressed, the in-plane luminance unevenness is reduced, and high quality display can be realized.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments. FIG. 1 is a diagram showing a configuration of a main part of an embodiment of the present invention. This embodiment is an embodiment in which only the waveform of the scanning voltage is distorted and applied to the input end of each scanning electrode. As a means for distorting the scanning voltage, it is arranged adjacent to the display pixel region 11A of the liquid crystal panel 11. Then, a dummy pixel region 11B in which a dummy pixel group is formed is provided on the input end side of the scanning electrode. The dummy pixel area 11B is the display pixel area 11A.
And the scanning electrode Y ₁ with the liquid crystal layer in between.
The dummy electrodes D _{1 to} Dk are arranged so as to intersect with each other in the extension of Yn to Yn.

FIG. 2 shows an electrical equivalent circuit of the liquid crystal panel 11 as seen from the power source side of the drive circuits 12 and 13 of this embodiment. For simplification, the figure is an equivalent circuit of the scan electrode Y _{1 on} the first line. As shown, the equivalent load circuit of the scan electrode Y ₁ can be represented as a ladder circuit as in FIG. The difference from FIG. 16 is that an equivalent load circuit of the dummy pixel group is added to the input side of the scan electrode Y ₁ . The load DP of the dummy pixel is determined by the electrode resistance Rd of each pixel.
x, Rdy and capacitance CD. Further, the input portion resistance Rxi is included at the input ends of the dummy electrodes D _{1 to} Dk.

The operation of the embodiment thus constructed will be described with reference to the waveform of the liquid crystal drive voltage applied to each pixel shown in FIG. 6A shows the non-selection voltage V ₄ of the signal voltage Vx, and FIG. 7B shows the voltage waveform when the scanning voltage Vy changes stepwise between the non-selection voltage V ₅ and the selection voltage V ₁ . The voltage having such a waveform is applied to the signal electrodes X _{1 to} X.
m, the dummy electrodes D _{1 to} Dk, and the scan electrode Y ₁ , the waveform of the liquid crystal drive voltage applied to the liquid crystal of each pixel is similar to that of the conventional example of FIG. ，
The impedance load P composed of Ry and the electrostatic capacitance CL causes distortion, resulting in a distortion waveform corresponding to the pixel position from the voltage input terminal. However, as described above, when the waveform distortion of the liquid crystal drive voltage becomes equal to or higher than a certain value, the influence of the impedance load P is reduced, and the waveform distortion is almost equal between pixels distant from the voltage input terminal.

In view of this phenomenon, according to the present embodiment, as shown in FIGS. 1 and 2, dummy pixel regions 11B are provided on the input side where the change in waveform distortion is remarkable, and k regions per scanning line are provided in this region. The dummy pixel (impedance load DP) is provided. As a result, the liquid crystal drive voltages Vd ₁ , Vd ₂ and Vdk of the dummy pixels in the dummy pixel region 11B are
As shown in FIGS. 3 (c), (d), and (e), the waveform has a waveform in which the distortion greatly changes as the distance from the input side increases. However, the liquid crystal drive voltage VL ₁ display pixel of the display pixel area _{11A, VL 2, VL (m} -1), VLm is drawing (f), (g), (h), a waveform shown in (i) Next to
Compared with the conventional example of FIG. 17, the difference in waveform distortion depending on the position is smaller (however, this is an example of m = 1920).

FIGS. 4A and 4B show changes in the effective value and the transmittance of the liquid crystal drive voltage applied to the liquid crystal of each pixel on the scanning electrode Y ₁ . In the figure, in addition to the number k of dummy pixels from the input terminal of the scan electrode Y ₁ of the first line, the number of display pixels m
(M = 1920) is taken on the horizontal axis, and the vertical axis of FIG.
The effective value of the liquid crystal drive voltage VL ₁ applied to the pixel of the signal electrode X ₁ of the first line is 100, and the execution value of the liquid crystal drive voltage of each pixel is shown as a relative value. Also, FIG.
The vertical axis indicates the transmittance TL of each pixel as a relative value, with the transmittance of the pixel of the dummy electrode D _{1 on} the first line being 100.

As is apparent from those figures, the effective value of the liquid crystal drive voltage applied to the liquid crystal of each pixel is attenuated as it is separated from the input terminal of the scan electrode Y ₁ , as in the conventional example of FIG. Further, the change in attenuation increases as it gets closer to the input terminal. In this embodiment, since the dummy pixel group is provided in the area where the change in the attenuation of the effective value of the liquid crystal drive voltage is large, the change in the attenuation of the effective value of the liquid crystal drive voltage of each pixel in the display pixel area 11A is small. It is suppressed. Along with this, as shown in FIG. 7B, the liquid crystal transmittance of each pixel also includes a dummy pixel group in the area 11B in which the change in transmittance is large. Therefore, each pixel in the display pixel area 11A is The change in the transmittance of the liquid crystal is suppressed to a small level.

Therefore, according to the present embodiment, in the liquid crystal display device, a plurality of dummy electrodes having the same arrangement as the signal electrodes of the display pixel group are arranged on the input side of the scanning voltage, and the dummy pixel electrode Since another dummy electrode group is provided, the change in the waveform distortion of the liquid crystal drive voltage of each pixel in the scan electrode direction caused by the resistance Ry of the scan electrode of the display pixel group and the capacitance CL of the liquid crystal becomes small. The difference in the effective value of the liquid crystal drive voltage applied to the liquid crystal of each pixel is reduced, and thus the difference in the transmittance of the pixel in the scan electrode direction is suppressed to a small value.
As a result, in-plane luminance unevenness is reduced, and a high quality liquid crystal display device can be realized.

In the above embodiment, the number k of dummy electrodes of the dummy pixel group is determined by the electrical equivalent load and the input resistance of the display pixel group of the liquid crystal display device to be improved, and the required luminance unevenness standard. Set appropriately according to the degree.

Further, since it is not necessary to display the dummy pixel group, the applied voltages to the dummy electrodes D ₁ , D ₂ , ..., Dk are different from the signal electrodes X ₁ , X ₂ ,. m-1),
It does not have to be the same as the signal voltage Vx applied to Xm.
In short, the voltage applied to the dummy electrodes D ₁ , D ₂ , ..., Dk is set so as to cause the required waveform distortion in the dummy pixel region 11B.

Further, since the dummy pixel area 11B is an area which is not related to display, the dummy pixel area 11B is made to be covered with the cover 16 as shown in FIG. As a result, the user can work without any discomfort by seeing only the necessary information displayed in the display pixel area 11A.

FIG. 6 is a circuit diagram of a main part of an equivalent load circuit of a liquid crystal display panel and an input section according to another embodiment of the present invention. In this embodiment, instead of the dummy pixel group of FIG.
The impedance circuit Z ₁ having a function equivalent to this is inserted in the input side of the scan electrode. That is, the impedance circuit Z ₁ is composed of the resistance element and the capacitance element so as to cause the waveform distortion of the scanning voltage, similarly to the dummy pixel group of FIG. This suppresses the difference in the effective value of the liquid crystal drive voltage applied to the liquid crystal of each pixel depending on the position, and reduces the in-plane luminance unevenness.

Specifically, the impedance circuit Z1 is
As shown in FIG. 7, the resistor Rd is connected to the input portion of the scanning voltage Vy.
It is configured by connecting y, Rdx and the capacitance CD in the same manner as the circuit configuration of the liquid crystal pixel section. The values of the resistors Rdy and Rdx of the impedance circuit Z ₁ and the capacitance CD are set so that the same waveform distortion as the waveform distortion of the scanning voltage Vy caused by the plurality of dummy pixel groups in FIG. 1 is obtained. According to this, the structure is simpler than that of the embodiment shown in FIG. 1, and the same effect can be obtained while saving space.

Further, as shown in FIG. 8 instead of FIG. 7, the waveform distortion of the liquid crystal drive voltage of each pixel in the display pixel region 11A is made to be the same to some extent by providing the resistor RD at the input portion of the scanning voltage Vy. can do. That is, by the resistance RD of the input portion of the scanning voltage Vy and the capacitance CL of the liquid crystal of the pixel of the signal electrode X ₁ of the display pixel group,
It is possible to increase the impedance of the pixels of the line 1 and increase the waveform distortion of the liquid crystal drive voltage applied to the liquid crystal of the pixels of the 1st line. The change is small.

9A to 9G, the applied voltage VZ of the capacitance CD of the impedance circuit Z1 and the liquid crystal drive voltage V applied to the liquid crystal of each pixel in the display pixel area 11A.
L ₁ , VL ₂ , VL ₁₉₁₉ , and VL ₁₉₂₀ are shown. As shown, since the scanning voltage Vy is greatly distorted by the impedance circuit Z ₁ , the liquid crystal drive voltages VL ₁ , VL ₂ , VL ₁₉₁₉ ,
The difference in VL ₁₉₂₀ waveform distortion can be reduced.

It should be noted that the resistance RD of FIG. 8 also causes VL ₁ , VL ₂ , and V to some extent as shown in FIGS. 9A to 9G.
The difference between the L ₁₉₁₉ and VL ₁₉₂₀ waveform distortions can be reduced.

FIGS. 10A and 10B are shown in FIGS.
FIG. 8 is a diagram showing the relative value of the effective value of the liquid crystal drive voltage applied to the liquid crystal of each pixel and the relative transmittance of the liquid crystal of each pixel in the same manner as in (b). As is clear from the figure, the impedance circuit Z ₁ can reduce the difference between the relative value of the effective value of the liquid crystal drive voltage of each pixel and the relative transmittance depending on the pixel position, reduce the in-plane luminance unevenness, and improve the display quality. Can be increased.

In the embodiment of FIG. 7 or the embodiment of FIG. 8, the values of the resistors Rdy and Rdx and the capacitance CD or the resistor RD of the impedance circuit Z ₁ are the input portion resistance and the pixel group of the liquid crystal display device. Set according to the equivalent load and display quality requirements.

Since the impedance circuit Z ₁ has nothing to do with display, the voltage applied to the dummy electrode Xd is the signal voltage V applied to the signal electrodes X ₁ , X ₂ , ..., Xm of the display pixel group.
It does not have to be the same as x.
Set according to ₁ to how much the voltage waveform is distorted.

Further, the impedance circuit Z ₁ is not limited to the circuit shown in FIG. 7, and an arithmetic circuit or the like may be used as long as it has a function of causing waveform distortion of the scanning voltage. It is possible to reduce the fluctuation of the transmittance of the pixel in the scanning electrode direction to reduce the in-plane luminance unevenness, and it is possible to realize a liquid crystal display device of high quality display.

FIG. 11 shows the impedance circuit Z _{1 of} FIG.
An example in which the liquid crystal display panel 11 is formed in an adjacent region outside the display region will be described. As a result, a specific structure example for realizing the capacitance CD and the resistance Rdy or RD is shown in FIG.
2 and FIG. As shown in FIG. 12, the capacitance CD is realized by making the dummy electrode and the extension of the scanning electrode face each other with the liquid crystal layer interposed therebetween. The value of the electrostatic capacitance CD is set by setting the width WC of the scanning electrode in the portion forming the electrostatic capacitance CD.
Is the width WT of the input terminal or the width WP of the scan electrode of the pixel.
_{For example,} the width WD of the dummy electrode Xd in the portion forming the capacitance CD is made wider than the width WP2 of the signal electrode of the display pixel. That is,
A liquid crystal (or another dielectric may be used) is sandwiched in a region where the scanning electrode Yn and the dummy electrode Xd intersect to form a capacitance CD. According to this, the capacitance value can be arbitrarily set by adjusting the widths WC and WD of the electrodes.

Further, as shown in FIG. 13, the resistor Rdy or RD is provided with a region having an electrode width WR narrowed with respect to the width WT of the input terminal or the width WP of the electrode of the pixel, and this region is provided with the resistor Rdy or RD. Used as. According to this, the resistance value can be arbitrarily set by adjusting the width WR of the electrode.

Although each of the embodiments shown in FIGS. 1, 2, 6, 7, and 8 above basically shows that the means for distorting the voltage waveform is integrally formed with the liquid crystal panel, the present invention is not limited to these. However, it is not limited to this, and can be provided outside the liquid crystal panel.

For example, the impedance circuit Z ₁ is shown in FIG.
As shown in FIG. 5, a well-known device or material may be used to form an integrated circuit in the scan electrode moving circuit 13. According to this, it is possible to use a highly reliable semiconductor manufacturing process with a circuit area smaller than that provided in the liquid crystal panel 11, and to provide the impedance circuit Z ₁ having a function of causing waveform distortion of the scanning voltage. Obtainable.

Further, the function of the impedance circuit Z ₁ having a function of causing the waveform distortion of the scanning voltage is provided by the liquid crystal panel 1.
1 and the scan electrode drive circuit 13 may be provided separately.

Further, in the above-mentioned embodiment, the description has been made focusing on eliminating the waveform distortion in the scanning electrode direction, but the present invention is not limited to this, and in the case of eliminating the luminance unevenness due to the waveform distortion in the signal electrode direction. Can also be applied.

[0044]

As described above, according to the present invention,
Since the means for distorting at least one of the signal voltage and the scanning voltage is provided in advance, the difference in the waveform distortion of the liquid crystal drive voltage due to the difference in the position of the pixel in the direction of the signal electrode or the scanning electrode is reduced, and the difference is applied to the liquid crystal of each pixel. The difference in the effective value of the liquid crystal driving voltage is reduced. As a result, it is possible to suppress a difference in liquid crystal transmittance of pixels due to a difference in position, reduce in-plane luminance unevenness, and achieve high quality display.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a liquid crystal drive device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a part of an electrically equivalent load circuit of FIG. 1 embodiment.

FIG. 3 is a diagram showing a waveform of a liquid crystal drive voltage of each pixel for explaining the operation of the embodiment shown in FIGS. 1 and 2;

4A and 4B are diagrams for explaining effects of the embodiments of FIGS. 1, 2, and 3, in which FIG. 4A is a diagram showing execution values of a liquid crystal drive voltage at each pixel position as relative values, and FIG. It is the figure which showed the transmittance | permeability of the liquid crystal in each pixel position by the relative value.

FIG. 5 is a diagram showing an embodiment of the present invention relating to the structure of the liquid crystal display device of the embodiment shown in FIGS. 1 and 2;

FIG. 6 is a main part circuit diagram of an equivalent load circuit as seen from the liquid crystal drive circuit side according to another embodiment of the present invention.

FIG. 7 is a circuit diagram of an embodiment embodying the embodiment of FIG. 6;

FIG. 8 is a circuit diagram of a modification of the embodiment of FIG. 7 of the present invention.

FIG. 9 is a diagram showing a waveform of a liquid crystal drive voltage of each pixel for explaining the operation of the embodiment of FIGS. 6 and 7;

10A and 10B are diagrams for explaining the effects of the embodiments of FIGS. 6 and 7, where FIG. 10A is a diagram showing relative values of execution values of the liquid crystal drive voltage at each pixel position, and FIG. 10B is each pixel position. FIG. 6 is a diagram showing the relative transmittance of the liquid crystal in FIG.

FIG. 11 is a diagram showing an embodiment relating to a configuration in which the embodiment of FIGS. 6 and 7 of the present invention is integrally formed with a liquid crystal panel.

FIG. 12 is a partial detailed diagram illustrating a method of setting the electrostatic capacitance of FIG.

13 is a partial detailed diagram illustrating a method of setting the resistance of FIG.

FIG. 14 is a diagram showing an example of a configuration in which the impedance circuit of FIGS. 6 and 7 of the present invention is provided in a scan electrode driving circuit.

FIG. 15 is an overall configuration diagram of a liquid crystal display device as an example to which the present invention is applied.

FIG. 16 is a circuit diagram showing a part of an equivalent load circuit of the liquid crystal panel viewed from the drive circuit.

FIG. 17 is a diagram showing a waveform of a liquid crystal drive voltage of each conventional pixel for explaining a problem to be solved by the present invention.

FIG. 18 is a diagram showing characteristics of a conventional liquid crystal device for explaining a problem to be solved by the present invention, FIG. 18A is a diagram showing effective values of a liquid crystal drive voltage at each pixel position as relative values,
(B) is a diagram showing the transmittance of the liquid crystal at each pixel position as a relative value.

FIG. 19 is a diagram showing the relationship between the transmittance of liquid crystal and the effective value of drive voltage.

[Explanation of symbols]

11 liquid crystal panel 11A display pixel area 11B dummy pixel area 12 signal electrode drive circuit 13 scan electrode drive circuit 16 cover Z ₁ impedance circuit D _{1 to} Dk dummy electrode X _{1 to} Xm signal electrode Y _{1 to} Yn scan electrode Rxi, Ryi input unit Resistance Rx, Ry Electrode resistance per pixel CL Capacitance per pixel P Liquid crystal load Rdx per pixel Rdx, Rdy Electrode resistance per dummy pixel CD Capacitance per dummy pixel Vx Signal voltage Vy Scan voltage VL _{1 to} Vm Liquid crystal drive voltage applied to liquid crystal of each pixel TR Transmissivity of liquid crystal VR Effective value of liquid crystal drive voltage VD _{1 to} Vdk Voltage applied to liquid crystal of each dummy pixel CD Impedance circuit Z ₁ static capacitance RD impedance circuit Z ₁ of the resistance Vz impedance circuit Z ₁ of the applied voltage

Claims (17)

[Claims] 1. A liquid crystal panel in which a plurality of signal electrodes and a plurality of scanning electrodes are arranged to cross each other across a liquid crystal layer to form pixels in a matrix, and a signal electrode and a scanning electrode of the liquid crystal panel, respectively. In a liquid crystal display device including a signal electrode driving circuit and a scanning electrode driving circuit for driving a liquid crystal of each pixel by applying a signal voltage and a scanning voltage having a stepwise changing waveform to one end, the voltage is applied to each electrode. A liquid crystal display device comprising means for distorting a waveform of at least one of the scanning voltage and the signal voltage by a certain amount. 2. The liquid crystal display device according to claim 1, wherein the means for distorting the waveform of the signal voltage or the scanning voltage is an impedance element. 3. The dummy according to claim 2, wherein the impedance element is formed on the input side of an electrode corresponding to a voltage that distorts a waveform by interposing the electrode and the other electrode across a liquid crystal layer. A liquid crystal display device characterized by being a pixel. 4. The liquid crystal display device according to claim 3, wherein the dummy pixel is integrally formed in a non-display area outside a display area of the liquid crystal display panel. 5. The liquid crystal display device according to claim 2, wherein the impedance element is incorporated as an integrated circuit in a drive circuit of an electrode corresponding to a voltage that distorts a waveform. 6. The dummy according to claim 2, wherein the impedance element is formed on the input side of an electrode corresponding to a voltage that distorts a waveform by crossing the electrode and the other electrode with a liquid crystal layer interposed therebetween. A liquid crystal display device comprising a pixel and an integrated circuit formed in a drive circuit of an electrode corresponding to a voltage that distorts the waveform. 7. The liquid crystal display device according to claim 2, wherein the impedance element includes a resistance and a capacitance. 8. A liquid crystal display device according to claim 3, wherein the dummy pixel has a structure invisible from the outside. 9. The dummy pixel according to claim 3, wherein the width of at least one electrode forming the dummy pixel is adjusted in order to arbitrarily set the capacitance of the impedance element. A liquid crystal display device characterized by the above. 10. The liquid crystal display device according to claim 3, wherein a plurality of the dummy pixels are provided for one electrode. 11. The liquid crystal display device according to claim 3, wherein the resistance of the impedance element is formed by using the extended portion of the electrode. 12. The liquid crystal display device according to claim 11, wherein the resistance value of the resistor is set by adjusting the width of the electrode. 13. The liquid crystal display device according to claim 1, wherein the means for distorting the waveform of the signal voltage or the scanning voltage is a resistance element. 14. The electrode according to claim 13, wherein the resistance element is an input side of an electrode corresponding to a voltage that distorts a waveform and is arranged in a non-display area outside a display area of the liquid crystal display panel. A liquid crystal display device formed by using. 15. The liquid crystal display device according to claim 13, wherein the resistance element is incorporated in a drive circuit of an electrode corresponding to a voltage that distorts a waveform. 16. The electrode according to claim 13, wherein the resistance element is an input side of an electrode corresponding to a voltage that distorts a waveform and is arranged in a non-display region outside a display region of the liquid crystal display panel. A liquid crystal display device, comprising: a resistance element formed by using a resistor element and a resistance element incorporated in a drive circuit of an electrode corresponding to a voltage that distorts the waveform. 17. The liquid crystal display device according to claim 13, wherein the width of the electrode is adjusted and set in order to arbitrarily set the resistance value of the resistance element.