CN100492111C - Discharge circuit and liquid crystal display device using the discharge circuit - Google Patents

Abstract

The invention relates to a discharge circuit, comprising: a first input end, a second input end, a level generating circuit, a transistor and a resistor, where the first input end is connected with the source of the transistor, the second input end is connected with the grid of the transistor through the level generating circuit, the drain of the transistor is earthed through the resistor, the level generating circuit receives a working voltage at the second input end and then generates a high level to turn on the transistor, and external charges are released through a discharge circuit composed of the first input end and the transistor. And the invention provides a LCD adopting the discharge circuit.

Description

Discharge circuit and liquid crystal display device using the discharge circuit

technical field

The invention relates to a discharge circuit and a liquid crystal display device using the discharge circuit.

Background technique

When the liquid crystal display device is turned off or suddenly cut off, the thin film transistor controlling the liquid crystal pixel is in the off state, but the off voltage applied to the gate of the thin film transistor cannot quickly become 0 volts, so the voltage applied to both ends of the liquid crystal pixel cannot be quickly turned off. Discharge, resulting in afterimage after shutdown. For this reason, the industry has developed various technologies to improve the afterimage phenomenon after shutdown.

A prior art liquid crystal display device for improving the afterimage phenomenon after power off is to connect a resistor in series between the off voltage input terminal (Vgl) and the ground to speed up the discharge speed of the off voltage of the gate of the thin film transistor, thereby speeding up the liquid crystal pixel. The rate at which the voltage is discharged.

However, the liquid crystal display device also continuously discharges through the resistor during normal operation, thereby increasing the extra power consumption of the system.

Contents of the invention

In order to solve the problem in the prior art that the liquid crystal display device increases the extra power consumption of the system during normal operation, the present invention provides a discharge circuit that does not increase the extra power consumption of the system during normal operation.

At the same time, it is necessary to provide a liquid crystal display device using the discharge circuit.

A discharge circuit, which includes a first input terminal, a second input terminal, a level generating circuit, a transistor and a resistor, the first input terminal is connected to the source of the transistor, and the second input terminal passes through the The level generating circuit is connected to the gate of the transistor, and the drain of the transistor is grounded through the resistor. The level generating circuit generates a high level to turn on the transistor after receiving an operating voltage at the second input end, and external charges are discharged through the discharge path formed by the first input end and the transistor. The level generating circuit includes Two inverters and a D flip-flop, wherein one inverter is connected in series between the second input end and the trigger input end of the D flip-flop, and the other inverter is connected in series between the second input end and the trigger input end of the D flip-flop. Between the clock control terminals of the D flip-flop, the output terminal of the D flip-flop is the output terminal of the level generating circuit.

A liquid crystal display device, which includes a discharge circuit, a driving integrated circuit, a plurality of data lines, a plurality of scanning lines, a plurality of thin film transistors and a plurality of pixel units, the driving integrated circuit includes a scanning driver and a data driver, and the discharging circuit includes A first input terminal, a second input terminal, a level generating circuit, a transistor and a resistor, the first input terminal is connected to the source of the transistor, the second input terminal is connected to the transistor through the level generating circuit The gate is connected, the drain of the transistor is grounded through the resistor, the scan driver is electrically connected to the plurality of scan lines, the data driver is electrically connected to the plurality of data lines, and the plurality of thin film transistors are located between the plurality of data lines and the plurality of scan lines At the intersection, the plurality of pixel units are electrically connected to the plurality of thin film transistors, and the level generating circuit generates a high level to turn on the transistor after receiving an operating voltage at the second input terminal, and the plurality of thin film transistors pass through the first The discharge path formed by the input terminal and the transistor is discharged, thereby accelerating the discharge speed of the pixel units. The level generating circuit includes two inverters and a D flip-flop, wherein an inverter is connected in series to the second input terminal. Between the trigger input end of the D flip-flop, another inverter is connected in series between the second input end and the clock control end of the D flip-flop, and the output end of the D flip-flop is the level generating circuit output terminal.

Compared with the prior art, the level generating circuit of the discharge circuit of the present invention continuously outputs low level to turn off the transistor when the liquid crystal display device is working normally, so as not to increase the extra power consumption of the system. The level generating circuit outputs a high level to turn on the transistor when the liquid crystal display device is turned off or is suddenly powered off, and the off-voltage input terminal of the liquid crystal display device is discharged through the transistor and the resistor, thereby effectively improving the afterimage phenomenon after shutdown .

Description of drawings

FIG. 1 is a schematic diagram of a liquid crystal display device of the present invention.

Fig. 2 is a circuit block diagram of the discharge circuit of the present invention.

Fig. 3 is a specific circuit structure diagram of the level generating circuit of the present invention.

Detailed ways

Please refer to FIG. 1 , which is a schematic diagram of a liquid crystal display device of the present invention. The liquid crystal display device 2 includes a data driver 21 , a scan driver 22 , a plurality of data lines 211 , a plurality of scan lines 221 , a plurality of thin film transistors 201 , a plurality of pixel units 202 and a plurality of storage capacitors 203 . The scan driver 22 includes a discharge circuit 220 .

The plurality of data lines 211 are electrically connected to the data driver 21 , and the plurality of scan lines 221 are electrically connected to the scan driver 22 . The plurality of thin film transistors 201 are located at the intersections of the plurality of data lines 211 and the plurality of scan lines 221, their gates are electrically connected to the plurality of scan lines 221, their sources are electrically connected to the plurality of data lines 211, and their drains are respectively connected to The plurality of pixel units 202 and the plurality of storage capacitors 203 .

Please refer to FIG. 2 , which is a circuit structure diagram of the discharge circuit of the present invention. The discharge circuit 220 includes a first input terminal 2201, a second input terminal 2202, a level generating circuit 2203, a transistor 2204 and a resistor 2205, and the gate of the transistor 2204 is connected to the first level generating circuit 2203 through the level generating circuit 2203. An input terminal 2201 is connected, the source of the transistor 2204 is connected to the second input terminal 2202 , and the drain of the transistor 2204 is grounded through the resistor 2205 . The first input terminal 2201 is used to receive an operating voltage, the second input terminal 2202 is electrically connected to the turn-off voltage input terminal (Vgl) (not shown) of the scan driver 22, and the level generating circuit 2203 is connected to the first input terminal 2203. When the terminal 2201 has a working voltage input, it generates a low level, and when the first input terminal 2201 has no working voltage input, it generates a high level. A specific circuit structure of the level generating circuit 2203 is shown in Figure 3, the level generating circuit 2203 includes a first inverter 2206, a second inverter 2207 and a D flip-flop 2208, the first The inverter 2206 is connected in series between the first input terminal 2201 and the trigger input terminal of the D flip-flop 2208, and the second inverter 2207 is connected in series between the first input terminal 2201 and the clock of the D flip-flop 2208 Between the control terminals, the output terminal of the D flip-flop 2208 is the output terminal of the level generating circuit 2203 .

When the liquid crystal display device 2 is working normally, the level generating circuit 2203 outputs a low level to the gate of the transistor 2204, and the transistor 2204 is turned off, that is, the second input terminal 2202 is disconnected from the ground.

When the liquid crystal display device 2 is turned off or powered off suddenly, the level generating circuit 2203 outputs a high level to the gate of the transistor 2204, and the transistor 2204 is turned on, that is, the second input terminal 2202 is connected to the ground. A discharge path is formed between the second input terminal 2202, the source and drain of the transistor 2204, the resistor 2205 and the ground, and the voltage of the off voltage input terminal becomes 0 volts rapidly, and the pixel unit 202 and the storage capacitor 203 The discharge speed is accelerated, so as to achieve the purpose of improving the afterimage after shutdown.

In the liquid crystal display device 2 of the present invention, the scan driver 22 and the data driver 21 can be replaced by a driver integrated circuit, so the discharge circuit 220 can also be arranged in the driver integrated circuit.

Compared with the prior art, the level generating circuit 2203 of the discharge circuit 220 of the present invention continuously outputs low level to turn off the transistor 2204 when the liquid crystal display device 2 is working normally, so as not to increase the extra power consumption of the system. The level generating circuit 2203 outputs a high level to turn on the transistor 2204 when the liquid crystal display device 2 is turned off or is suddenly powered off, and the off voltage input terminal of the liquid crystal display device 2 is discharged through the transistor 2204 and the resistor 2205, thereby enabling Effectively improve the afterimage phenomenon after shutdown.

Claims (4)

1. A discharge circuit comprising a first input terminal and a resistor, characterized in that: the discharge circuit also comprises a second input terminal, a level generating circuit and a transistor, the first input terminal and the transistor The source is connected, the second input end is connected to the gate of the transistor through the level generating circuit, the drain of the transistor is grounded through the resistor, and the level generating circuit generates a high voltage after the second input end receives an operating voltage. The level makes the transistor turn on, and the external charge is discharged through the discharge path formed by the first input terminal and the transistor. The level generating circuit includes two inverters and a D flip-flop, and one of the inverters is connected in series to the Between the second input end and the trigger input end of the D flip-flop, another inverter is connected in series between the second input end and the clock control end of the D flip-flop, and the output end of the D flip-flop is the The output terminal of the level generating circuit. 2. A liquid crystal display device, which includes a discharge circuit, a driver integrated circuit, some data lines, some scan lines, some thin film transistors and some pixel units, the driver integrated circuit includes a scan driver and a data driver, the scan The driver is electrically connected to the plurality of scanning lines, the data driver is electrically connected to the plurality of data lines, the plurality of thin film transistors are located at the intersections of the plurality of data lines and the plurality of scanning lines, and the plurality of pixel units are electrically connected to the plurality of thin film transistors, The discharge circuit includes a first input terminal and a resistor, and is characterized in that: the discharge circuit also includes a second input terminal, a level generating circuit and a transistor, the first input terminal is connected to the source of the transistor, the The second input end is connected to the gate of the transistor through the level generating circuit, the drain of the transistor is grounded through the resistor, and the level generating circuit generates a high level after the second input end receives an operating voltage to make the transistor turn on, the plurality of thin film transistors are discharged through the discharge path formed by the first input terminal and the transistor, thereby accelerating the discharge speed of the plurality of pixel units, the level generating circuit includes two inverters and a D flip-flop, one of which An inverter is connected in series between the second input terminal and the trigger input terminal of the D flip-flop, another inverter is connected in series between the second input terminal and the clock control terminal of the D flip-flop, and the D The output terminal of the flip-flop is the output terminal of the level generating circuit. 3. The liquid crystal display device as claimed in claim 2, wherein the discharge circuit is disposed in the driving integrated circuit. 4. The liquid crystal display device as claimed in claim 2, wherein the discharge circuit is disposed in the scan driver.

Images