Patent ID: 8654063

Claim:
A touch sensor embedded liquid crystal display device including a backlight unit which emits backlight when turned on and does not emit the backlight when turned off, the liquid crystal display device comprising: a liquid crystal panel comprising at least one touch sensor provided in each of n pixels, where n is a Natural Number; an ROIC readout part which receives a readout voltage value from readout lines provided in the liquid crystal panel; an ADC conversion part which converts an analog voltage value transmitted to the ROIC readout part into a digital value; a calculation part which calculates a calculated value by subtracting a corresponding value detected from the ADC conversion part when the backlight is not applied from a value detected from the ADC conversion part when the backlight is applied; and a position detection part for detecting a touch point on the liquid crystal panel if the calculated value from the calculation part is beyond a predetermined value, wherein the liquid crystal panel further comprises: at least one pixel circuit for each of the n pixels; a pair of sensors corresponding to the at least one pixel circuit, each of the pair of sensors comprising a first sensor detecting an amount of first light while the backlight unit is turned on to output a first voltage corresponding to the detected amount of the first light and a second sensor detecting an amount of second light while the backlight unit is turned off to output a second voltage corresponding to the detected amount of the second light, wherein a difference of the first voltage and the second voltage is the calculated value in the calculation part; and a first control line and a second control line, and at least one of the readout lines connected to the pair of sensors, wherein each of the first and second sensors comprises, a sensor transistor driven by a first control signal or a second control signal of the first and second control lines to sense light; a sensor capacitor for storing a signal corresponding to the light sensed by the sensor transistor; and a switching transistor connected to the sensor capacitor, to transmit the signal stored in the sensor capacitor to the at least one of readout lines when switched, wherein the first control signal is applied to the first sensor via the first control line during the backlight unit is turned on and the second control signal is applied to the second sensor during the backlight unit is turned off, and the first and second control signals are applied within a vertical blank period of a vertical synchronization signal of the liquid crystal panel.