JPH10221676A - Liquid crystal display device and driving method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of preventing the deterioration of picture quality caused by that adjacent gate pulses being in a V scanner are overlapped and to provide the driving method therefor. SOLUTION: This liquid crystal display device has row shaped gate lines X. column shaped signal lines Y and pixel parts (whose figures are omitted) arranged at intersection parts of the both lines. An individual part is drived by a TFT. A V scanner is constituted of a first V scanner 11 connected to odd numbered gate lines and a second V scanner 12 which is connected to even numbered gate lines and whose phase is the same phase as that of the first V scanner 11. Then, selection pulses are made to be alternately supplied on the gates every one line through buffer circuits and NAND circuits connected t the first and second V scanners 11, 12. Thus, it is extinguished that adjacent gate pulses are overlapped and the picture quality of this liquid crystal display device is improved.

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 used for, for example, a camera-integrated VTR or a liquid crystal projector and a method of driving the same, and more particularly, to improving the image quality by preventing adjacent gate pulses from overlapping in a V scanner. And a driving method thereof.

[0002]

2. Description of the Related Art In recent years, as devices with a liquid crystal display device represented by a camera-integrated VTR and a liquid crystal projector have become widespread, demands for higher performance of the liquid crystal display device have been increased. Is progressing. For example, a thin film transistor (Thin Fi
A liquid crystal display device employing an lm transistor (hereinafter simply referred to as “TFT”) has attracted attention due to its high-speed performance and has been adopted in many devices with a liquid crystal display device.

The outline of a conventional liquid crystal display device will be briefly described with reference to FIG. FIG. 3 is a circuit diagram showing a main configuration of a conventional liquid crystal display device.

A conventional liquid crystal display device has a row-shaped gate line X, a column-shaped signal line Y, a liquid crystal cell disposed at each intersection of the two, and a pixel portion (not shown) including a storage capacitor. . Each pixel unit is driven by the TFT1. The V scanner 2 supplies a selection pulse to a gate line X via a buffer circuit 3 as shown in the figure. The gate line X has an internal resistance R1, R2, R3.
-Rn is apparently connected.

As shown in timing charts showing the operation of the conventional V scanner shown in FIGS. 3 and 4, the V scanner 2 sequentially scans selection pulses V _1L , V _2L , V _3L. A pixel portion for one row is selected every (1H). The H scanner (not shown) is connected to each signal line Y within 1H.
Are sequentially sampled, and the video signal Vsig is written to the selected pixel portion for one row. More specifically, the video signal Vsi is connected via a horizontal switch 4 connected to each signal line Y and controlled to open and close by a horizontal sampling pulse (not shown).
g.

The relationship among the internal resistances R1, R2, R3,... Rn of the gate line X connected to the buffer circuit 3 is as follows.
R1 <R2 <R3 << Rn. That is, the V _1L is immediately after the buffer circuit 3 in the TFT 1, different waveform depending of the selection pulse is the time constant of V _1R immediately before the selected gate line X is turned off, V _1R is compared to V _1L pulse The waveform becomes dull. When the waveform of the selection pulse becomes dull, as shown in FIG. 4, the selection pulses V _1R , V _2R , V
An area A where _3Rs are simultaneously turned on occurs. This means that the gate lines X are selected redundantly, and the video signal Vsig is written overlapping the selected gate line X. As a result, the video signals Vsig are mixed. Therefore, there is a problem that the image quality of the liquid crystal display device is adversely affected.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to reduce the image quality of a liquid crystal display device caused by overlapping adjacent gate pulses in a conventional V scanner. It is an object of the present invention to provide a liquid crystal display device and a driving method thereof.

[0008]

In order to solve the above-mentioned problems of the prior art, the following measures have been taken. That is, the liquid crystal display device of the present invention includes a V scanner to which a plurality of gate lines arranged in a row are connected, an H scanner to which a plurality of signal lines arranged in a column are connected, and each of a gate line and a signal line. In a liquid crystal display device including a pixel portion provided at an intersection, a V scanner is divided into a first V scanner to which odd-numbered gate lines are connected and a second V scanner to which even-numbered gate lines are connected. At the same time, a NAND circuit and a buffer circuit having one end on the input side connected to the n gate line of the first V scanner are connected in series, and the n-1 gate line of the second V scanner is connected to the non-connection end on the input side of the NAND circuit. (Except for the first gate line)
A NAND circuit and a buffer circuit are connected in series to the n gate line of the second V scanner, and the end of the n-1 gate line of the first V scanner is connected to the non-connection end on the input side of the NAND circuit via an inverter circuit. By connecting, the first V
This prevents the gate line of each of the scanner and the second V scanner from being redundantly selected.

Further, the driving method of the liquid crystal display device according to the present invention comprises a V-scanner which sequentially scans the gate lines arranged in a row to select a pixel portion for one row every one horizontal period, and a V-scanner within one horizontal period. In a method of driving a liquid crystal display device having an H scanner for sampling a signal line arranged in a column and writing a video signal to a pixel portion for one row selected, a V scanner is connected to an odd gate line. 1 V scanner and a second V scanner for selecting even gate lines, and n gate lines of the first V scanner are connected to n gates of the second V scanner.
-1 The gate line does not rise until the end of the gate line is completely turned off, and the n gate line of the second V scanner is connected to the n gate line of the first V scanner.
The selection pulse is alternately supplied from the two V scanners every gate line so that the gate line does not rise until the end of the -1 gate line is completely turned off. As a result, the selection pulses of the n gate line and the immediately preceding n-1 gate line do not overlap, and the deterioration of the image quality of the liquid crystal display device caused mainly by the overlap of the selection pulses can be prevented.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

First, the configuration of the liquid crystal display device of the present invention will be described with reference to FIG. FIG. 1 is a circuit diagram showing a main configuration of the liquid crystal display device of the present invention. The same portions as those of the liquid crystal display device of the related art are denoted by the same reference numerals, and the description thereof will be partially omitted.

The liquid crystal display device of the present invention has a row-shaped gate line X, a column-shaped signal line Y, and a pixel portion (not shown) arranged at each intersection of the two. Each pixel unit is driven by the TFT1. The V scanner includes a first V scanner 11 connected to an odd gate line,
The same-phase second V scanners 12 connected to the even-numbered gate lines are arranged at both ends of the pixel portion. These first V
Since the scanner 11 and the second V scanner 12 have the same phase, it is not necessary to newly increase input signals. As a second feature of the present invention, as will be described later in detail, the two V scanners are connected to each other through a buffer circuit and a NAND circuit.
The selection pulse is alternately supplied for each gate line.

That is, a buffer circuit 14 is connected in series to one gate line of the first scanner 11 via a NAND circuit 13, and an inverter circuit 1
5 is connected. The output of the inverter circuit 15 is the second V
NAND circuit 1 connected to two gate lines of scanner 12
6 is input to one end. A buffer circuit 17 is connected in series to the output of the NAND circuit 16, and an inverter circuit 18 is connected to the end of the buffer circuit 17.

The output of the inverter circuit 18 is the first
The signal is input to one end of a NAND circuit 19 connected to three gate lines of the V scanner 11. A buffer circuit 20 is connected in series to the output of the NAND circuit 19, and an inverter circuit 21 is connected to the end of the buffer circuit 20. The output of the inverter circuit 21 is input to one end of a NAND circuit 22 connected to four gate lines of the second V scanner 12. NAN
A buffer circuit 23 is connected in series to the output of the D circuit 22, and an inverter circuit 24 is connected to the end of the buffer circuit 23. Hereinafter, a NAND circuit and a buffer circuit are connected to each of the first V scanner 11 and the second V scanner 12 in the same manner.

Next, a method of driving the liquid crystal display device of the present invention will be described with reference to FIGS. FIG. 2 is a timing chart showing the operation of the V scanner of the liquid crystal display device of the present invention.

As shown in FIGS. 1 and 2, the first V scanner 11 includes a NAND circuit 13 and a buffer circuit 14.
Outputs a selection pulse V _1L via the selecting pixels of one row. The H scanner (not shown) sequentially samples the video signal Vsig within 1H by the horizontal switch 4 connected to each signal line Y, and writes the video signal Vsig to the selected one-row pixel portion. The selection pulse V _{1R at} the end of one gate line is a somewhat dull selection pulse (see FIG. 2) for the above-described reason.

The selection pulse V _{1R at} the end of one gate line is input to the NAND circuit 16 via the inverter circuit 15, but the selection pulse for the two gate lines is apparent from the timing chart of FIG. In this way, the operation of the inverter circuit 15 and the NAND circuit 16 does not rise until the selection pulse V _{1R at} the end of one gate line is completely turned off, and prevents the selection pulses of the one gate line and the two gate lines from overlapping. I do.

Similarly, the selection pulse V at the end of the two gate lines
_2L is connected to the first V scanner 11 via the inverter circuit 18.
, The selection pulse V _3L of the three gate lines is _supplied to the inverter circuit 1.
8 and the NAND circuit 19 do not rise until the selection pulse V _{2L at} the end of the two gate lines is completely turned off, preventing the selection pulses of the two gate lines and the three gate lines from overlapping.

Similarly, by outputting a selection pulse for each gate line via a NAND circuit and a buffer circuit connected to the first V scanner 11 and the second V scanner 12, a gate pulse of an adjacent gate pulse in the V scanner is output. Prevent overlap. Thus, it is possible to prevent the image quality of the liquid crystal display device from being deteriorated mainly due to the overlap of the selection pulses. Also, the first V scanner 1 of the present invention
Since the first and second V scanners 12 have the same phase, there is no need to newly increase the number of input signals.

The present invention is not limited to the above embodiment,
Various embodiments can be employed. For example, in the present embodiment, an example of a circuit for preventing overlap of adjacent gate pulses by a combination of an inverter circuit and a NAND circuit has been described. However, other than the above-described circuit, another configuration having a similar function may be used. Needless to say, the present invention can be appropriately applied without departing from the gist of the present invention.

[0021]

As described above, according to the liquid crystal display device and the method of driving the same according to the present invention, the selection pulses are alternately supplied from the two V scanners for each gate line. The overlapping gate pulses do not overlap, and the image quality of the liquid crystal display device can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a main configuration of a liquid crystal display device of the present invention.

FIG. 2 is a timing chart illustrating an operation of a V scanner of the liquid crystal display device of the present invention.

FIG. 3 is a circuit diagram illustrating a configuration of a main part of a conventional liquid crystal display device.

FIG. 4 is a timing chart showing an operation of a V-scanner of a conventional liquid crystal display device.

[Explanation of symbols]

1 ... thin film transistor (TFT), 2 ... V scanner, 3 ... buffer circuit, 11 ... 1st V scanner, 1
2... 2nd V scanner, 13, 16, 19, 22... N
AND circuit, 14, 17, 20, 23 ... buffer circuit, 15, 18, 21, 24 ... inverter circuit

Claims (2)

[Claims] 1. A V-scanner to which a plurality of gate lines arranged in a row are connected, an H-scanner to which a plurality of signal lines arranged in a column are connected, and at each intersection of the gate line and the signal line. In a liquid crystal display device provided with a pixel portion provided, the V scanner is divided into a first V scanner to which odd-numbered gate lines are connected and a second V scanner to which even-numbered gate lines are connected, and A NAND circuit and a buffer circuit are connected in series to the n gate line of the first V scanner, and the end of the n-1 gate line of the second V scanner is connected to an unconnected input terminal of the NAND circuit via an inverter circuit. A NAND circuit and a buffer circuit are connected in series to the n gate line of the second V scanner, and the n-1 gate of the first V scanner is connected to a non-connection input terminal of the NAND circuit. By connecting the end of bets line through an inverter circuit, a liquid crystal display device characterized by preventing each gate line of the first 1V scanner and said second 2V scanner is selected duplicate. 2. A V-scanner for sequentially scanning gate lines arranged in a row to select a pixel portion for one row every one horizontal period, and sampling a signal line arranged in a column in one horizontal period. H to write the video signal to the pixel portion of one row selected by H
A method of driving a liquid crystal display device having a scanner, wherein the V-scanner is divided into a first V-scanner for selecting an odd-numbered gate line and a second V-scanner for selecting an even-numbered gate line. The line does not rise until the end of the n-1 gate line of the second V scanner is completely turned off, and the n gate line of the second V scanner is not turned on until the end of the n-1 gate line of the first V scanner is completely turned off. A method for driving a liquid crystal display device, characterized in that control is performed so that gate lines of the first V-scanner and the second V-scanner are not selected redundantly.