A DC negative dimming circuit and liquid crystal display device

Abstract

The present invention provides a DC negative dimming circuit to convert the first dimming signal output by the main chip of a liquid crystal display device into a second dimming signal and output it to a backlight module, which includes a first and a second electric switch and the first to third resistors, the control terminal of the first electrical switch is connected to the dimming signal output terminal of the main chip through the first resistor to receive the first dimming signal, the first terminal of the first electrical switch is connected to the output terminal of the main chip through the second resistor Connect to the voltage terminal to receive the first high level signal, the second terminal is connected to the control terminal of the second electric switch, and the first terminal of the second electric switch is connected to the dimming signal receiving terminal of the backlight module to output the second The dimming signal is grounded through the third resistor, the second end receives the second high level signal, and the levels of the first and second dimming signals are opposite. Therefore, the first dimming signal of the main chip can be directly supplied to the backlight module after being converted into the second dimming signal, thereby meeting the requirement of the liquid crystal display device for direct current negative dimming.

Description

technical field [0001] The invention relates to the field of display technology, in particular to a direct current negative dimming circuit and a liquid crystal display device. Background technique [0002] There are two ways to adjust the brightness of LCD TVs at this stage. One is DC dimming, and the other is PWM dimming. Among them, the PWM dimming method makes the current flowing through the LED light string continuously turn on and off through high-frequency switching. By controlling the conduction duty cycle of the light string, the brightness adjustment is realized. Therefore, in the process of PWM dimming, the LED light-emitting diode is actually blinking continuously. In order to avoid the recognition range of human eyes, TV manufacturers generally increase the dimming frequency to above 100Hz. The DC dimming method achieves dimming by linearly adjusting the current of the LED light string. There is no switch in the DC dimming mode, which realizes flicker-free ...

AI Technical Summary

Problems solved by technology

However, the dimming signal of the main chip cannot be directly supplied to the LED backlight control chip, so it cannot meet the requirements of the TV system for DC negative dimming

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