KR940004964Y1 - Signal composition circuit of tft-lcd - Google Patents

Abstract

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Description

Image signal correction circuit for driving TFT-LCD panel

1 is a conventional TFT-LCD panel driving circuit diagram.

2 is a video signal correction circuit for driving a TFT-LCD panel according to the present invention applied to the circuit of FIG.

3 is a waveform diagram of each part of FIG.

* Explanation of symbols for main parts of the drawings

1 TFT-LCD Panel 2 Upper Source Driver

3: lower source driver 4: gate driver

5: Triggering unit 6: Correction voltage generating unit

7: correction unit VR: variable resistor

The present invention relates to a TFT-LCD panel driving, and more particularly, to a TFT-LCD panel driving video signal correction circuit for solving the reduction of the voltage applied to the liquid crystal by the resistance of the gate line.

Conventionally, as shown in FIG. 1, the TFT-LCD panel 1 and the odd numbered array of TFTs Q and liquid crystal capacitors C are arranged in an array at the intersections of the gate lines GL and the source lines SL. The upper source driver 2 for driving the source line SL of the gate, and the gate driver for sequentially driving the lower source driver 3 and the gate line GL for driving the even-numbered source line SL. TFT-LCD panel drive circuit was driven by (4).

In the conventional circuit, as the image signal VS is applied, the upper source driver 2 and the lower source driver 3 sequentially sample the image signal VS during the 1H horizontal period of the image signal VS. The gate driver 4 sequentially generates the gate driving voltage of the TFT Q during the 1H horizontal period of the image signal VS, thereby sequentially turning on the gates of the arranged TFT Q. When the gate of the TFT 5 is turned on, the image signal sampled by the upper source driver 2 and the lower source driver 3 is applied to the source of the TFT Q. Therefore, the capacitor C of the liquid crystal C is connected to the image signal VS. The voltage is charged and the image is displayed. Reference numeral R denotes a resistor connected to the gate of the TFT (Q).

However, in the prior art, a resistance exists in the gate line, and the resistance increases due to the thinning of the line width of the metal line according to the trend of higher density of TFT-LCD panels.

The resistance of the gate line reduces the voltage applied to the gate of the TFT arranged on the right side rather than the voltage applied to the gate of the TFT arranged on the left side of the TFT-LCD panel.

Therefore, since the voltage applied to the capacitor of the liquid crystal decreases from left to right, there is a problem in that the brightness of the right side is reduced from the left side of the screen.

The present invention is to solve such a problem, an object of the present invention is to provide a video signal correction circuit for driving TFT-LCD panel to increase the voltage applied to the right pixel than the left side of the screen by generating a correction voltage of the triangular wave will be.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

FIG. 2 is a video signal correction circuit diagram for driving a TFT-LCD panel according to the present invention applied to the circuit of FIG. 1. A tree for generating a trigger signal (TS1, TS2) by receiving a horizontal synchronization signal (HS) in the circuit of FIG. In response to the rejection 5 and the trigger signals TS1 and TS2, the correction voltage generator 6 and the image signal including the correction voltages CS1 and CS2, that is, the variable resistor VR for generating a triangular wave and varying the amount of correction. And a correction unit 7 for supplying the addition signal AS to the upper source driver 2 and the lower source driver 3 by adding the correction voltages CS1 and CS2 to the VS1 and VS2. The same reference numerals in Fig. 1 denote the same parts.

Referring to FIG. 3, which is a waveform diagram of each part of FIG. 2, when the horizontal synchronization signal HS as shown in FIG. 3 (b) is input to the trigger unit 5, the trigger unit 5 The trigger signal TS1 as shown in FIG. 3 (c) is generated in the falling portion of the horizontal synchronization signal HS to discharge the output of the correction voltage generator 6, and the third (in the rising portion of the horizontal synchronization signal HS). The charging of the correction voltage generation unit 6 is started by generating the trigger signal TS2 as shown in FIG.

The correction voltage generator 6 receives the trigger signals TS1 and TS2 as inputs, and corrects the positive correction voltage CS1 as shown in FIG. 3 (e) and the negative correction voltage CS2 as shown in FIG. 3 (f). Occurs. The amount of correction may be varied by adjusting the slope of the correction voltages CS1 and CS2 by adjusting the variable resistor VR according to the change of the resistance R value of the gate line GL.

Since the TFT-LCD panel 1 must be AC driven, the image signal VS is inverted into positive and negative polarities by a certain period. The correction unit 7 adds the correction voltage CS1 and the positive image signal VS1 shown in FIG. 3 (a) to generate the corrected image signal AS1 as shown in FIG. (CS2) and the negative image signal VS2 of the opposite phase to the third phase (a) are added to generate the corrected image signal AS2 as shown in the third (h) figure so that the upper and lower source passive circuits 2, 3) will be supplied. The dotted lines shown in FIGS. 3 (g) and 3 (h) show the positive and negative video signals VS1 and VS2, respectively. The corrected video signals AS1 and AS2 are dotted lines. Since the voltages CS1 and CS2 for compensating for the reduction of the gate driving voltage due to the resistance R of the gate line GL are added to the image signals VS1 and VS2 of the portion, the liquid crystal is moved from left to right of the screen. The brightness of the entire screen can be made constant by compensating for the reduction of the voltage applied to the screen.

As described above, according to the present invention, the triangular wave correction voltage is applied to the upper source driving part of the TFT-LCD panel to increase the voltage applied to the right pixel rather than the left side of the screen, thereby improving the screen quality and making the screen brightness uniform. It can be effective.

Claims (2)

TFT-LCD panel with positive and negative video signals VS1 and VS2 as inputs, and having upper and lower source drivers 2 and 3 and a gate driver 4 for driving the TFT-LCD panel 1. In the driving circuit, a triangular wave is generated according to the trigger unit 5 and the trigger signals TS1 and TS2 that receive the horizontal synchronization signal HS and generate the respective trigger signals TS1 and TS2 in the falling and rising portions. The correction voltage generator 6 for generating the correction voltages CS1 and CS2 of the video signal AS1 and the added video signal AS1 by adding the correction voltages CS1 and CS2 to the respective video signals VS1 and VS2. And a correction unit (7) for supplying AS2 to the upper and lower source driving units (2, 3). 2. The video signal correction circuit according to claim 1, wherein the correction voltage generator (6) includes a variable resistor (VR) to vary the inclination of the triangular wave to obtain a desired correction amount.