| 摘要 |
PURPOSE: A circuit for controlling screen brightness is provided to automatically adjust the screen brightness by detecting a DC level of an inputted image signal and outputting a correction waveform according to the detected result. CONSTITUTION: A signal input unit including an A/D converting unit(41), a memory(42) and a D/A converting unit(43) converts an inputted image signal into a digital image signal, temporarily stores the digital image signal, converts the digital image signal into an analog image signal, and outputs the analog image signal to an LCD(Liquid Crystal Display) driving unit(49). A timing generating unit(45) separates a synchronous signal from the inputted image signal, generates various timing signals on the basis of the separated synchronous signal, and provides the various timing signals to the signal input unit. A DC level detecting unit(46) detects a DC level from the inputted image signal. A peak level detecting unit(47) detects a peak level in a frame according to the timing signal of the timing generating unit(45) from the digital image signal of the signal input unit. A gamma and gain control unit(48) detects a gamma correction value and a gain adjustment value using at least one or more of the DC level and the peak level, and outputs the gamma correction value and the gain adjustment value to the LCD driving unit(49) to correct an LCD output waveform.
|
