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A highly stable, wide-range LED backlight brightness adjustment method and drive circuit

A technology of brightness adjustment and driving circuit, applied in static indicators, instruments, etc., can solve the problem of unstable driving of LED backlight circuit, and achieve the effect of improving stability

Active Publication Date: 2019-04-02
NO 55 INST CHINA ELECTRONIC SCI & TECHNOLOGYGROUP CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to solve the problem of unstable driving of the existing LED backlight circuit, to invent a method for adjusting the brightness of the LED backlight with high stability and wide range, and to provide a corresponding driving circuit at the same time

Method used

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  • A highly stable, wide-range LED backlight brightness adjustment method and drive circuit
  • A highly stable, wide-range LED backlight brightness adjustment method and drive circuit

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0014] Such as figure 1 shown.

[0015] A highly stable and wide-range brightness adjustment method for LED backlight, which uses MCU controller to control the protection voltage of constant current IC to make LED drive circuit enter constant voltage mode or constant current mode, and at the same time output PWM pulse signal to control LED brightness ;In the high-brightness backlight mode, the drive circuit enters the constant current mode, samples the output current, and keeps it in a high and stable state through the automatic gain control closed-loop loop; in the low-brightness backlight mode, the drive circuit enters the constant voltage mode, through the DC- The DC boost drives the backlight circuit, and performs open-loop PWM switching to control the brightness. In this way, high stability and wide-range brightness adjustment of the LED backlight are finally realized.

Embodiment 2

[0017] Such as figure 2 shown.

[0018] A highly stable and wide-range LED backlight drive circuit, which includes an MCU controller and a LED backlight constant current and constant voltage drive circuit. The PWM1 output by the MCU controller is connected to the PWM pin of the constant current IC, and the PWM2 is connected to the G pole of the MOS transistor Q3; the IO of the MCU controller is connected to the G pole of the MOS transistor Q2. In the LED backlight constant current and constant voltage drive circuit, the ISP and ISN pins of the constant current IC are connected to the resistor R2 in series in the LED; the FB pin of the constant current IC is connected to the resistor R1 to the output terminal of the booster circuit, and R3 to the ground. Connect R4 and MOS tube Q2 to ground. One end of the resistors R1, R2, and R3 is connected to the FB pin of the constant current IC at the same time.

[0019] 1) When the required LED backlight brightness is higher than a c...

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Abstract

A high-stability, wide-range LED backlight brightness adjustment method and drive circuit are characterized in that it includes an MCU controller and a LED backlight constant current and constant voltage drive circuit. The MCU controller makes the LED drive circuit enter the constant voltage mode or constant current mode by controlling the protection voltage of the constant current IC, and at the same time outputs the PWM pulse signal to control the LED brightness. In the high-brightness backlight mode, the drive circuit enters the constant current mode, samples the output current, and maintains it in a highly stable state through the automatic gain control closed-loop loop. In the low-brightness backlight mode, the drive circuit enters the constant voltage mode, drives the backlight circuit through DC-DC boost, and performs open-loop PWM switching to control the brightness. Thus, the high stability and wide-range brightness adjustment of the LED backlight can be finally realized. In the case of using a constant current IC, the present invention simultaneously realizes the constant current and constant voltage driving circuit of the LED backlight, which can effectively improve the stability and brightness adjustment range of the LED backlight circuit.

Description

technical field [0001] The invention relates to the field of liquid crystal display, in particular to an LED backlight driving circuit in a liquid crystal display device. Background technique [0002] LED backlight refers to the use of LED (light emitting diode) as the backlight of the LCD screen. Compared with the traditional CCFL (cold cathode tube) backlight, LED has the characteristics of low power consumption, low calorific value, high brightness and long life. The mainstream LED constant current drive circuit is mainly aimed at the application scenarios in the daily illumination environment, and the adjustment range of the backlight brightness is small. In other special fields, especially in airborne application scenarios, a wide dimming range is required (0.5cd / m 2 ~45000 cd / m 2 ). Moreover, when the commonly used constant current drive circuit is at low brightness, the LED operating current is set to be very small, and the current sampled by the constant current ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G09G3/34G09G3/36
CPCG09G3/3406G09G3/36
Inventor 赵红伟殷照陈建军张伟
Owner NO 55 INST CHINA ELECTRONIC SCI & TECHNOLOGYGROUP CO LTD