Patent ID: 8174486

Claim:
A light sensing circuit for a liquid crystal display having a backlight unit, the light sensing circuit comprising: sensor unit comprising: a first sensor that detects an external light to output a first current value; a third sensor that detects an internal light generated from the backlight unit to output a third current value; and a second sensor that detects a peripheral light isolated from the external light and the internal light to output a second current value, wherein the sensor unit outputs a first differential value between the third current value and the second current value and a second differential value between the first current value and the second current value; a voltage generator generating a reference voltage in response to the first differential value and generating a sensing voltage in response to the second differential value; and a readout circuit generating brightness information of the external light using the reference voltage and the sensing voltage, wherein the second and third sensors are serially connected between a first voltage and a second voltage lower than the first voltage to comprise a first subtraction circuit that outputs the first differential value, and the second and first sensors are serially connected between the first voltage and the second voltage to comprise a second subtraction circuit that outputs the second differential value.