Patent ID: 7733336

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 a brightness of an ambient surrounding the liquid crystal panel and generating a sense signal, wherein the sense signal generated by the photo sensor is a current type sense signal; a signal processor adjusting a luminance of the light supplied by the backlight unit according to the sense signal; and a sensor controller converting the current type sense signal to a voltage type sense signal, wherein the sensor controller includes: first to third thin film transistors each having a gate electrode, a source electrode and a drain electrode; a variable element connected to the third thin film transistor; an enable signal input terminal receiving an enable signal, the enable signal having one of high and low level voltages; a ground terminal receiving a ground signal; a variable signal input terminal applying a variable signal to the variable element; and an output terminal outputting an output voltage to the signal processor, wherein the photo sensor is connected to the ground terminal and the gate electrodes of the second and third thin film transistors.