Shenzhen China Star Optoelectronics Technology Co., Ltd.

Chingyuan Yang

Chengming He

Mei-Hao Wu

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.

Backlight module and an LCD thereof

A backlight module detecting abnormal lamp tubes and an LCD employing such a backlight module are proposed. The LCD includes a voltage calculator for detecting voltage applied on ends of a lamp tube to monitor the lamp tube. Once the lamp tube becomes abnormal, the voltage varies accordingly. The voltage calculator calculates a voltage signal from a plurality of lamp tubes and produces a voltage value. A protection circuit regards the voltage value as a feedback signal to decide if there are any abnormalities. Once any of the lamp tubes is abnormal, the protection circuit transmits the voltage signal to a pulse-width modulated integrated circuit (PWM IC) to activate a protective function. The protection circuit of the present invention obtains the protection signal by sampling the voltage signal of the ends of the lamp tube and then gets the control signal by means of the calculation of the voltage calculator. Thus, voltage level retrieved from the protection signal are less easily affected by dimming and temperature.

Backlight module detecting abnormal lamp tubes and an LCD thereof

The present invention provides a backlight module, and the backlight module has an LED module which has a plurality of light emitting diodes averagely divided into a plurality of light strings. Forward voltages of the light emitting diodes are between a minimum forward-voltage value and a maximum forward-voltage value, and each of the light strings at least has one first light emitting diode and one second light emitting diode. The first light emitting diode has the minimum forward-voltage value and the second light emitting diode has the maximum forward-voltage value. The backlight module is contributive to lower power loss on a constant current control circuit.

Backlight module

The present invention provides a driving circuit and a driving method of a backlight module of a display apparatus. The driving method comprises the following steps: utilizing a phase detector to detect voltage phases of an inductor and a capacitor of a resonant circuit; utilizing a frequency adjusting module to obtain an operation frequency according to a phase detection signal; and utilizing a driving chip to drive a DC-to-AC power stage circuit according to the operation frequency. The invention can improve the transformation efficiency of the driving circuit.

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Shenzhen, China

Chingyuan Yang