LED backlight driving circuit, driving method of LED backlight driving circuit and liquid crystal display device

A technology of backlight driving circuit and LED light bar, applied in static indicators, instruments, etc., can solve the problems of not being able to provide short-circuit protection for LED light bars, and the inability to identify LED backlight driving circuits.

Active Publication Date: 2015-05-20
TCL CHINA STAR OPTOELECTRONICS TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] When one or more LED lamp beads in the LED light bar are short-circuited, the LED backlight driving circuit using the above technology cannot be identified, so it cannot provide effective short-circuit protection for the LED light bar

Method used

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  • LED backlight driving circuit, driving method of LED backlight driving circuit and liquid crystal display device
  • LED backlight driving circuit, driving method of LED backlight driving circuit and liquid crystal display device
  • LED backlight driving circuit, driving method of LED backlight driving circuit and liquid crystal display device

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0058] like figure 1 , 2 As shown, the comparison unit in this embodiment includes a subtractor U1, a first input terminal of the subtractor U1 is coupled to the feedback voltage V1; a second input terminal thereof is coupled to the first reference voltage VF1. The difference between the feedback voltage and the first reference voltage VF1 can be directly output through the subtractor U1, so that the subsequent drive unit only needs to judge whether the difference exceeds a preset deviation value, and if it exceeds, the drive power supply module is turned off.

[0059] The driving unit includes a comparator U2, the first input terminal of the comparator U2 is coupled to the output terminal of the subtractor U1; the second input terminal of the comparator U2 is coupled with a second reference voltage VF2;

[0060] The second reference voltage VF2 is equal to the preset deviation value, and when the output voltage of the subtractor U1 is greater than the second reference voltag...

Embodiment 2

[0064] like figure 1 , 3 As shown, the comparison unit in this embodiment includes a first controllable switch Q1, a first resistor R1, a second resistor R2 and a third resistor R3; the source of the first controllable switch Q1 is coupled to A reference high-level signal VCC, the drain of which is coupled to the ground terminal of the LED backlight drive circuit through the second resistor R2; the feedback voltage V1 is coupled to the gate of the first controllable switch Q1 through the third resistor R3; the second A reference voltage VF1 is coupled to the drain of the first controllable switch Q1; the source of the first controllable switch Q1 is also coupled to an inverter 43, and the output terminal of the inverter 43 is coupled to the drive unit ;

[0065] The inverter 43 includes a second controllable switch Q2, a third controllable switch Q3, a fourth resistor R4, and a fifth resistor R5;

[0066] The source of the second controllable switch Q2 is coupled to the ref...

Embodiment 3

[0077] like Figure 4 Shown, a kind of driving method of LED backlight driving circuit, described LED backlight driving circuit comprises LED light bar, drives the power supply module of LED light bar, and described driving method comprises steps:

[0078] A: Connect the voltage dividing resistor R0 in series at the output end of the LED light bar; preset the first reference voltage VF1 and the deviation value;

[0079] The first reference voltage VF1 is greater than or equal to the maximum voltage at both ends of the divider resistor R0 when the normal LED light bar is at maximum brightness;

[0080] B: The voltage at both ends of the voltage dividing resistor R0 is compared with the first reference voltage VF1 as a feedback voltage, and if the difference between the feedback voltage and the first reference voltage VF1 exceeds a preset deviation value, the power supply module is controlled to be turned off.

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PUM

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Abstract

An LED backlight driving circuit and a driving method therefor, and a liquid crystal display apparatus. The LED backlight driving circuit (10) comprises an LED light bar (30) and a power module (20) driving the LED light bar (30). An output end of the LED light bar (30) is separately coupled to a short-circuit protection module (40) and a divider resistor (R0). The short-circuit protection module (40) comprises a comparison unit (41) and a driving unit (42) coupled to the comparison unit (41). Voltages at two ends of the divider resistor (R0) are used as feedback voltages (V1, V2) coupled to the comparison unit (41). The comparison unit (41) is also coupled to a preset first reference voltage (VF1). When a value, by which the feedback voltages (V1, V2) exceed the first reference voltage (VF1), is greater than a preset deviation value, the driving unit (42) controls the power module (20) to be switched off. When the first reference voltage (VF1) is greater than or equal to a maximum brightness of the LED light bar in a normal state, the voltages at the two ends of the divider resistor (R0) are divided. The LED backlight driving circuit (10) can provide a short-circuit protection function when an LED lamp bead is in a short circuit.

Description

technical field [0001] The invention relates to the field of liquid crystal display, and more specifically, relates to an LED backlight driving circuit, a driving method thereof, and a liquid crystal display device. Background technique [0002] The liquid crystal display device includes a liquid crystal panel and a backlight module. The backlight module includes multiple strings of LED light strips and their drive circuits. In the current design, due to the different voltages of the LED light strips, there will be some voltage differences. This voltage difference is loaded to a constant voltage. On the current drive chip or other devices, it will cause the temperature of the constant current drive chip or other devices to rise, so there is a solution to this problem: by changing the current size and duty cycle of each string, keep each string The same average current and the same voltage across. For example, if the voltage of a string of LED light strips is too small, you ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G09G3/36G09G3/34
CPCG09G3/342G09G2330/04G09G2330/12
Inventor 张先明杨翔
Owner TCL CHINA STAR OPTOELECTRONICS TECH CO LTD
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