JPH06202592A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To provide a liquid crystal display device capable of reducing the occurrence of a glitch and obtaining an excellent picture display. CONSTITUTION:This device is the device capable of displaying an image with a halftone on a liquid crystal display pannel 6 by using a pulse modulation system, and signal electrode driving signals Yn, Yn for displaying the halftone are generated by signal electrode driving circuits 41, 42 to be imparted to respective signal electrodes in the liquid crystal display pannel 6. On the other hand, this device is constituted so that a pair of scanning electrode driving signals Xn, Xn are constituted to a set by two pieces from the scanning electrode driving circuit 7, and are imparted to the scanning electrodes Xj, Xj to be constituted in scanning side double matrix, and the interval between the scanning electrodes Xj, Xj in respective sets are short-circuited at the time of nonselecting the scanning electrode.

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 capable of displaying halftones by using a pulse modulation method.

[0002]

2. Description of the Related Art Conventionally, as a liquid crystal display device for driving a liquid crystal display panel used for a television receiver or the like, an image signal is converted into a digital signal of a plurality of bits, which is given to a signal electrode drive circuit and predetermined by pulse modulation. There is a method in which an image having a halftone can be displayed by generating the signal electrode drive signal of (1) and applying the signal electrode drive signal to the signal electrode and the scan electrode together with the scan electrode drive signal.

By the way, when displaying a halftone A and a halftone B on the liquid crystal display panel 1 as shown in FIG.
For such a liquid crystal display panel 1, a signal electrode waveform for continuing to output a halftone A as a signal electrode drive signal and a signal electrode waveform for outputting a halftone A in the first half and a halftone B in the second half, respectively. In the second half, Fig. 6 (a)
The signal electrode waveforms Ya and Yb shown in (b) are given.

However, these signal electrode waveforms Ya, Y
b may affect the scan electrode waveform via the LC circuit, and as a result, the scan electrode waveform X1 is affected by the rise and fall of the signal electrode waveforms Ya and Yb.
In some cases, a glitch as shown in FIG. 7C may occur in the non-selected portion. Then, the glitch generated in the non-selected portion of the signal electrode waveform may cause, for example, uneven brightness or crosstalk called so-called string pull, particularly in the C portion on the screen of the liquid crystal display panel 1. There was a problem that the quality of the screen deteriorates.

[0005]

In the liquid crystal display device for driving the conventional liquid crystal display panel as described above, a glitch is generated in the non-selected portion of the scan electrode waveform by switching the rising and falling edges of the signal electrode waveform. , The effect of this glitch causes uneven brightness on the liquid crystal display panel, and
There is a drawback that the quality of the screen on the liquid crystal display panel is remarkably deteriorated, such as crosstalk called string pulling.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a liquid crystal display device which can reduce the occurrence of glitches and can obtain a high-quality screen display.

[0007]

According to the present invention, in a liquid crystal display device having a liquid crystal display panel in which scanning electrodes and signal electrodes are arranged in a matrix, the scanning electrodes are constituted by two sets each. One of the pairs faces the odd-numbered signal electrodes and the other faces the even-numbered signal electrodes, and the scanning electrodes in the above-mentioned pair are supplied with voltages of opposite polarities at the time of selection and are not selected. The time is short-circuited.

[0008]

As a result, according to the present invention, the liquid crystal display panel is constructed in the common side double matrix so that a pair of scan electrode drive signals in a set are formed in groups of two and applied to the scan electrodes. By short-circuiting the scan electrodes of each set when the scan electrodes are not selected, it is possible to cancel the glitches generated in the non-selected portions of the waveforms of the scan electrodes and reduce the occurrence thereof.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of the same embodiment. In the figure, 1 is a controller, and this controller 1 controls all circuits in a centralized manner. Reference numeral 2 denotes a sync separation circuit. The sync separation circuit 2 separates a sync signal from a video signal which is an image signal and supplies it to the controller 1.

The video signal is sent to the A / D converter 3 through the sync separation circuit 2 and is converted into a k-bit digital signal there. Then, the k-bit digital signal output from the A / D converter 3 is sent to the signal electrode drive circuits 41 and 42, respectively.

The signal electrode drive circuit 41 includes the controller 1
Further, the timing signal CKFS is directly applied, and the signal electrode drive circuit 42 is adapted to be supplied with the timing signal CKFS from the controller 1 via the inverter 5 so as to generate the signal electrode drive signals Yn and Yn, respectively. I have to. Signal electrode drive circuit 4 in this case
Signal electrode drive signals Yn and Yn generated by
Have the same content but opposite polarities. The signal electrode drive signals Yn and Yn are supplied to the signal electrode drive circuit 4
1, the signal electrodes Y1, Y3, Y5 of the liquid crystal display panel 6
, And are applied to the signal electrodes Y2, Y4, Y6 of the liquid crystal display panel 6 by the signal electrode drive circuit 42, respectively.

On the other hand, 7 is a scan electrode drive circuit, which receives a timing signal CKFC from the controller 1 and which outputs a pair of scan electrode drive signals Xn.
, Xn are generated as a set, and the scan electrode drive signals Xn, Xn forming this set are generated as scan electrodes Xj, X of the liquid crystal display panel 6.
I am trying to give it to j. In this case, the scanning electrodes Xj and Xj of the liquid crystal display panel 6 are configured in groups of two, one of which is opposed to the odd-numbered signal electrode and the other is opposed to the even-numbered signal electrode. It is supposed to do.

FIG. 2 shows a schematic structure of such a scan electrode driving circuit 7. In this case, when the scan electrodes are selected, the output buffer analog switches 71 and 72 are turned on by the non-selection signal S at this time, and the analog switches 73 and 7 are turned on.
4 is turned off, and the scan electrode drive signals Xn and Xn are output by the timing signal CKFC as V0 (high level selection potential) or V4 (low level selection potential) in a reverse polarity relationship. , When the scan electrodes are not selected, the analog switches 71, 72 are generated by the non-selection signal S.
Is turned off and the analog switches 73 and 74 are turned on, the scan electrode drive signals Xn and Xn sources are short-circuited via these analog switches 73 and 74, and the non-selection potential V2 is output.

In the liquid crystal display panel 6, the scanning electrodes X
Since j and Xj alternately take over the adjacent pixels as shown by the white and broken lines in FIG. 4, the leading line 82 between the pixels of the scan electrodes Xj and Xj is
A voltage reverse to that of the display is applied, which may adversely affect the screen display. Therefore, in order to prevent this, a display shielding portion 81 shown by a mesh is provided in a portion unrelated to the display of each scanning electrode Xj, Xj.

Next, the operation of the embodiment thus constructed will be described. Also here, an example will be described in which the area A of the halftone a and the area B of the halftone b are displayed on the liquid crystal display panel as shown in FIG. In this case, the signal electrode drive circuits 41 and 42 output the signal electrode drive signals Yn and Yn having the same content but opposite polarities in accordance with the k-bit digital signal output from the A / D converter 3.

The signal electrode drive signal Yn of the signal electrode drive circuit 41 is applied to the signal electrodes Y1, Y3, Y5 of the liquid crystal display panel 6.
, And the signal electrode drive signal Yn is applied to the signal electrodes Y2, Y4, Y6, ... Of the liquid crystal display panel 6. Then, the signal electrode drive circuits 41 and 42 output the signal electrode drive signals Yn and Yn for the k-bit image data and apply them to the liquid crystal display panel 6. The signal electrode drive signal Yn here is the signal drive waveform Ya shown in FIG. 3A for continuously outputting only the halftone A with respect to the timing signal CKFS, and the halftone A from the middle of the first halftone A. It is output as the signal drive waveform Yb shown in FIG. Further, the signal electrode drive signal Yn is the signal drive waveform Y shown in FIG.
a is output as the signal drive waveform Yb shown in FIG. 6E for outputting the halftone A first and then the halftone B halfway.

As a result, the segment drive waveforms Ya, Y
Due to the influence of the rising and falling edges of b, a glitch as shown in FIG. 7C is about to occur in the non-selected portion of the scan electrode waveform of the scan electrode Xj corresponding to the scan electrode drive signal Xn.
Further, due to the rise and fall of the signal electrode waveforms Ya and Yb, the scan electrode X corresponding to the scan electrode drive signal Xn is generated.
A glitch as shown in FIG. 7F is about to occur in the non-selected portion of the scan electrode waveform of j.

However, in the scan electrode driving circuit 7 when the scan electrodes are not selected, the analog switches 71 and 72 are turned off and the analog switches 73 and 74 are turned on by the non-selection signal S, as shown in FIG. Through the analog switches 73 and 74, the scan electrode drive signals Xn and X
The n source is shorted, which causes scan electrodes Xj and Xj.
3C is short-circuited, the glitches shown in FIGS. 3C and 3F generated in the non-selected portion of the scan electrode waveform act to cancel each other, and the actual scan electrode waveform is the same. As shown in FIG. 7G, glitches can be reduced.

Therefore, in this way, the paired scan electrode drive signals Xn and Xn are paired with the scan electrode Xj.
, Xj, the liquid crystal display panel 6
Are arranged in a double matrix on the scanning side, and when the scanning electrodes are selected, the polarities of the scanning electrode drive signals Xn and Xn for the pair of scanning electrodes Xj and Xj are given in reverse, and the scanning electrodes are not selected. Since a short circuit is made between Xj and Xj, it is possible to cancel the glitch generated in the non-selected portion of each scan electrode waveform, thereby reducing the generation of the glitch, and on the liquid crystal display panel 6 due to the influence of the glitch. It is possible to prevent uneven brightness, and to reduce the crosstalk phenomenon called string pulling.
A high quality screen display can be obtained on the liquid crystal display panel.

The present invention is not limited to the above-mentioned embodiments, and can be carried out by appropriately modifying it without changing the scope of the invention.
For example, in the above-described embodiment, the scanning-side dual matrix is configured so that the scanning electrodes Xj and Xj alternately take the pixels every other scanning electrode, but the pixels may be taken up every plural scanning electrodes.

[0021]

According to the present invention, the liquid crystal display panel is constructed in a common side double matrix so that a pair of scanning electrode drive signals in a pair are formed in pairs and are applied to the scanning electrodes. When the electrodes are not selected, the scan electrodes of each set are short-circuited to cancel the glitches generated in the non-selected portion of each scan electrode waveform, so that the occurrence of the glitches can be reduced and the liquid crystal caused by the glitches can be reduced. It is possible to prevent uneven brightness on the display panel, reduce the crosstalk phenomenon called stringing, and obtain a good-quality screen display on the liquid crystal display panel.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of a scan electrode driving circuit used in an embodiment.

FIG. 3 is a waveform chart for explaining the operation of the embodiment.

FIG. 4 is a diagram for explaining another embodiment of the present invention.

FIG. 5 is a diagram for explaining a display example on a liquid crystal display panel.

6 is a waveform chart for explaining the operation of the liquid crystal display panel of FIG.

[Explanation of symbols]

1 ... Controller, 2 ... Synchronous separation circuit, 3 ... A / D converter, 41, 42 ... Signal electrode drive circuit, 5 ... Inverter,
6 ... Liquid crystal display panel, 7 ... Scan electrode drive circuit, 71, 7
2, 73, 74 ... Analog switch.

Claims (1)

[Claims] 1. A liquid crystal display device comprising a liquid crystal display panel in which scanning electrodes and signal electrodes are arranged in a matrix, wherein the scanning electrodes are configured in groups of two, one of which is an odd number. The scanning electrodes in the above group are supplied with voltages of opposite polarities when they are selected, and are short-circuited when they are not selected. Liquid crystal display device.