Patent ID: 8692760

Claim:
A backlight unit comprising: a backlight including a plurality of light sources to generate light; and a backlight control unit configured to control an on/off time of the backlight in units of at least one frame using an off time setting value set by a user and an external dimming control signal and to control the amount of light emitted from the backlight, wherein the backlight control unit includes, a driving Micro Controller Unit (MCU) configured to receive the external dimming control signal and to generate a pulse width modulation (PWM) signal corresponding to a duty ratio of the dimming control signal and to generate a delay time setting value (DTS) such that the PWM signal is delayed according to the off time setting value, wherein the DTS is generated by subtracting the on time of the backlight from the off time setting value; and at least one backlight control IC configured to receive the PWM signal and the DTS from the MCU and to receive the external dimming signal, wherein the at least one backlight control IC delays the PWM signal in correspondence with the DTS and supplies or cuts off backlight driving currents according to the delayed PWM signal, wherein the backlight control unit sets the off time of the backlight according to the off time setting value, and delays a Pulse Width Modulation (PWM) signal such that each LED group of the backlight is turned on in synchronization with the set off time of the backlight and then turns each LED group on using the delayed PWM signal, wherein the off time setting value is preset by the user as a digital value of a period from a start time of every frame period to a time when the backlight is turned off according to the size of the liquid crystal panel or the use of the liquid crystal panel, wherein the off time setting value is set such that the backlight is held at the on state during a rising period of liquid crystal of pixel regions included in any one horizontal line among a plurality of horizontal lines included in the liquid crystal display panel, and is set such that the backlight is turned off in synchronization with a falling time of liquid crystal of pixel regions included in any one horizontal line among a plurality of horizontal lines.