Patent ID: 7768497

Claim:
A liquid crystal display device, comprising: a liquid crystal panel; a backlight unit supplying light to the liquid crystal panel; a photo sensor detecting an ambient brightness of surrounding the liquid crystal panel; and a signal processor configured to adjust a luminance of the light supplied by the backlight unit and includes a current to voltage converter converting an current analog-type sense signal output from the photo sensor into a voltage analog-type sense signal, an analog-to-digital (A/D) converter converting the voltage analog-type sense signal into a voltage digital-type sense signal, a latch part temporarily storing the voltage digital-type sense signal and outputting the voltage digital-type sense signal to the backlight unit, an OR gate logically summing the voltage digital-type sense signal from the analog-to-digital (ND) converter and the voltage digital-type sense signal stored in the latch part, a multiplexer selecting a reference voltage according to a result of the OR gate, and a reference voltage part supplying a hysteresis voltage to the A/D converter according to the reference voltage.