LED BACKLIGHT SOURCE USED IN LCD DEVCICE AND LCD DEVICE THEREFORE

• US 20160249427A1
• Filed: 10/13/2014
• Published: 08/25/2016
• Est. Priority Date: 09/29/2014
• Status: Abandoned Application

• Current Assignee: Shenzhen China Star Optoelectronics Technology Co., Ltd. (TCL Technology Group Corp.)
• Original Assignee: Shenzhen China Star Optoelectronics Technology Co., Ltd. (TCL Technology Group Corp.)
• Inventors: CHEN, Xinhong, YANG, Xiang
• Application Number:
  US14/426,381
• Publication Number:
  US 20160249427A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/44 with an active control inside an LED matrix
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

An LED backlight source used in a LCD device is disclosed. It comprises a boost circuit, boosting the input voltage to the operating voltage of an LED string; a current control module, connecting to a negative end of the LED string for modulating the operating voltage of the LED string; a microcontroller, providing the current control module with the second square wave signal to control the current control module for achieving current modulation; a boost driver chip, providing the boost circuit with a first square wave signal to the boost circuit for achieving voltage boost function; the boost driver chip receives a feedback regulation voltage found by the microcontroller and changes a duty ratio of the first square wave signal provided by the boost circuit according to the feedback regulation voltage, for modulating the operating voltage of the LED string.

Claims

1. An LED backlight source for a LCD device, comprising:

a boost circuit, configured to boost an input voltage to an operating voltage of an LED string;

a current control module, configured to connect to a negative end of the LED string for modulating the operating voltage of the LED string;

a microcontroller, configured to provide the current control module with the second square wave signal to control the current control module for achieving current modulation;

a boost driver chip, configured to provide the boost circuit with a first square wave signal to the boost circuit for achieving voltage boost function;

the boost driver chip receives a feedback regulation voltage found by the microcontroller and changes a duty ratio of the first square wave signal provided by the boost circuit based on the feedback regulation voltage, for modulating the operating voltage of the LED string.

2. The LED backlight source as claimed in claim 1, wherein the boost circuit comprises an inductor, a first MOS transistor, and a rectifier diode, wherein an end of the inductor is used for receiving the input voltage;

another end of the inductor connects to a positive electrode of the rectifier diode and an drain of the first MOS transistor;

a negative electrode of the rectifier diode connects to a positive end of the LED string, a gate of the first MOS transistor connects to a square wave signal output end of the boost driver chip; and

a source of the first MOS transistor is electrically grounded.

3. The LED backlight source as claimed in claim 1, wherein the current control module comprises a second MOS transistor and a forth resistor, wherein a gate of the second MOS transistor connects to an LED operating current control end of the microcontroller;

a drain of the second MOS transistor connects to a negative end of the LED string;

a source of a third MOS transistor connects to an end of the forth resistor; and

another end of the forth resistor is electrically grounded.

4. The LED backlight source as claimed in claim 1, wherein the LED backlight source further comprises a first resistor, a second resistor and a third resistor, wherein an end of the first resistor connects to a positive end of the LED string;

an end of the second resistor is electrically grounded;

an end of the third resistor connects to a feedback regulation voltage output end of the microcontroller;

another end of the first resistor;

another end of the second resistor and another end of the third resistor all connect to a feedback regulation voltage input end of the microcontroller.

5. The LED backlight source as claimed in claim 1, wherein the LED string comprises a predetermined number of serially connected LEDs.

6. An LCD device, comprising a LCD panel and a LED backlight source in opposite to the LCD panel, wherein the LED backlight source provides light with the LCD panel so that the LCD panel displays images, wherein the LED backlight source comprises:

a boost circuit, configured to boost an input voltage to an operating voltage of an LED string;

a current control module, configured to connect to a negative end of the LED string for modulating the operating voltage of the LED string;

a microcontroller, configured to provide the current control module with a second square wave signal to control the current control module for achieving current modulation;

a boost driver chip, configured to provide the boos circuit with a first square wave signal to the boost circuit for achieving voltage boost function; and

the boost driver chip receives a feedback regulation voltage found by the microcontroller and changes a duty ratio of the first square wave signal provided by the boost circuit according to the feedback regulation voltage, for modulating the operating voltage of the LED string.

7. The LCD device as claimed in claim 6, wherein the boost circuit comprises an inductor, a first MOS transistor, and a rectifier diode, wherein an end of the inductor is used for receiving the inputting voltage;

another end of the inductor connects to a positive electrode of the rectifier diode and an drain of the first MOS transistor;

a negative electrode of the rectifier diode connects to a positive end of the LED string;

a gate of the first MOS transistor connects to a square wave signal output end of the boost driver chip; and

a source of the first MOS transistor is electrically grounded.

8. The LCD device as claimed in claim 6, wherein the current control module comprises a second MOS transistor and a forth resistor, wherein a gate of the second MOS transistor connects to a LED operating current control end of the microcontroller;

a drain of the second MOS transistor connects to a negative end of the LED string; and

a source of a third MOS transistor connects to an end of the forth resistor, another end of the forth resistor is electrically grounded.

9. The LCD device as claimed in claim 6, wherein the LED backlight source further comprises a first resistor, a second resistor and a third resistor, wherein an end of the first resistor connects to a positive end of the LED string;

an end of the second resistor is electrically grounded;

an end of the third resistor connects to a feedback regulation voltage output end of the microcontroller;

another end of the first resistor; and

another end of the second resistor and another end of the third resistor al connect to a feedback regulation voltage input end of the microcontroller.

10. The LCD device as claimed in claim 6, wherein the LED string comprises a predetermined number of serially connected LEDs.