Patent ID: 8279245

Claim:
A liquid crystal display comprising: a liquid crystal display panel; a backlight unit that provides light to the liquid crystal display panel; a panel drive circuit that drives signal lines of the liquid crystal display panel; a timing controller that supplies a video signal to the panel drive circuit and controls an operation timing of the panel drive circuit; a data stretching unit that modulates an internal video signal using a data stretching curve determined depending on a brightness of the internal video signal for a self-screen drive; an internal memory that stores the modulated internal video signal; a self-screen drive controller that generates a dimming signal having a dimming ratio less than a dimming ratio in a normal drive to reduce a luminance of the backlight unit and generates an internal timing signal to extract the modulated internal video signal from the internal memory; a scaler unit that generates an external video signal and an external timing signal for the normal drive; a selection unit that supplies one of an output of the self-screen drive controller and an output of the scaler unit to the timing controller in response to a mode selection signal; an internal power circuit that generates driving voltages required to drive the panel drive circuit, the timing controller, and the self-screen drive controller; an external power circuit that generates a power input to the internal power circuit and generates a power for driving the scaler unit; and a microprocessor that blocks an output of the external power circuit from being supplied to the scaler unit in the self-screen drive, wherein the data stretching unit fixes a slope of lower gray level, calculates an average luminance of the internal video signal corresponding to 1 frame, adjusts a slope of upper gray level between a previously set minimum slope and a previously set maximum slope depending on the calculated average luminance, and connects the fixed slope of lower gray level and the adjusted slope of upper gray level to determine a data stretching curve.