Backlight module and an LCD thereof
AssigneeShenzhen China Star Optoelectronics Technology Co., Ltd.
InventorsChengming He, Chingyuan Yang
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Abstract
A backlight module and a liquid crystal display (LCD) device thereof are proposed. The backlight module includes a DC/DC converter producing a positive/negative voltage level. The backlight module can output the positive and negative levels of driving voltage from an output end of the inverter to drive LEDs through alternately switching. Besides, a constant current can be obtained with designs of power on/off periods and energy-storing inductors to prevent LEDs employing current limiting resistors from having too low current efficiency and from being burnt out.
Claims10
A backlight module comprising a power end for supplying a power supply voltage, characterized in that the backlight module further comprising:
- a converter electrically connected to the power end, comprising a switch signal generator for generating a switch signal, the converter for converting the power supply voltage to a positive voltage level of a driving signal in response to a first voltage level of the switch signal, and for converting the power supply voltage to a negative voltage level of the driving signal in response to a second voltage level of the switch signal, the positive and negative voltage levels being generated alternately, the converter comprising:
- a capacitor element coupled to the lighting device in parallel;
- a first switch electrically coupled to the power end, turning on when the switch signal is at the first voltage level;
- a second switch electrically coupled to the power end, turning on when the switch signal is at the first voltage level;
- a first inductor element electrically coupled to the first switch;
- a second inductor element electrically coupled to the power end, the second switch, and the capacitor element;
- a third switch electrically coupled to the second inductor element and the power end, turning on when the switch signal is at the second voltage level;
- a first diode comprising a first positive end directly coupled to the first inductor element and the second switch, and a first negative end directly coupled to the capacitor element;
- and
- a second diode comprising a second positive end directly coupled to the capacitor element and the first negative end of the first diode, and a second negative end directly coupled to the second inductor element and the third switch;
- and
- a lighting device electrically connected to the converter, for generating light based on the positive and negative voltage levels of the driving voltage from the converter.
An LCD device comprising a power end for supplying a power supply voltage and an LCD panel for displaying an image, characterized in that the LCD device further comprising:
- a converter electrically connected to the power end, comprising a switch signal generator for generating a switch signal, the converter for converting the power supply voltage to a positive voltage level of a driving signal in response to a first voltage level of the switch signal, and for converting the power supply voltage to a negative voltage level of the driving signal in response to a second voltage level of the switch signal, the positive and negative voltage levels being generated alternately, the converter comprising:
- a capacitor element coupled to the lighting device in parallel;
- a first switch electrically coupled to the power end, turning on when the switch signal is at the first voltage level;
- a second switch electrically coupled to the power end, turning on when the switch signal is at the first voltage level;
- a first inductor element electrically coupled to the first switch;
- a second inductor element electrically coupled to the power end, the second switch, and the capacitor element;
- a third switch electrically coupled to the second inductor element and the power end, turning on when the switch signal is at the second voltage level;
- a first diode comprising a first positive end directly coupled to the first inductor element and the second switch, and a first negative end directly coupled to the capacitor element;
- and
- a second diode comprising a second positive end directly coupled to the capacitor element and the first negative end of the first diode, and a second negative end directly coupled to the second inductor element and the third switch;
- and
- a lighting device electrically connected to the converter, for generating light based on the positive and negative voltage levels of the driving voltage from the converter.
Dependencies are inferred from the claim text.