Driving circuit of backlight module
AssigneeChunghwa Picture Tubes, Ltd.
InventorsShih-Meng Chang, Chia-Lin Liu, Chi-Neng Mo, Ke-Horng Chen, Chi-Lin Chen
Life of this patent
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Abstract
A driving circuit of a backlight module is provided. The driving circuit has a dimming unit used for transmitting signals, wherein the dimming unit can adjust a current flowing through a light-emitting diode (LED) according a pulse width modulation signal and an enable signal, so as to adjust a light-emitting intensity of the LED. In the present invention, fewer devices are used to implement the dimming unit, and a transmission gate is replaced by a N-type transistor and a P-type transistor, such that a chip area and a circuit cost of the driving circuit are reduced.
Claims9
A driving circuit of a backlight module, wherein the backlight module includes a first light-emitting diode (LED) unit, the driving circuit comprising:
- a voltage conversion unit, coupled to a first end of the first LED unit for providing a driving voltage to the first LED unit;
- a current adjusting unit, coupled to a second end of the first LED unit for adjusting a conducted current of the first LED unit according to a first current adjusting signal;
- a current mapping unit, outputting a reference voltage;
- and
- a dimming unit, coupled between the current mapping unit and the current adjusting unit, and comprising a plurality of driving units, wherein a first driving unit outputs the first current adjusting signal according to a first pulse width modulation (PWM) signal, a first enable signal and the reference voltage,
- wherein the first driving unit comprises:
- an AND gate, having a first input terminal and a second input terminal respectively receiving the first PWM signal and the first enable signal;
- a N-type transistor, having a drain coupled to the reference voltage, a source coupled to the current adjusting unit and outputting the first current adjusting signal, and a gate coupled to an output terminal of the AND gate;
- and
- a P-type transistor, coupled between the reference voltage and ground, and a gate of the P-type transistor being coupled to the output terminal of the AND gate.
Dependencies are inferred from the claim text.