Patent ID: 8144112

Claim:
A backlight modulation circuit comprising: a backlight source; a backlight driving circuit configured for driving the backlight source; a rough modulation key and a fine modulation key configured for generating a rough triggering signal and a fine triggering signal respectively; a scaler configured for receiving the rough triggering signal and the fine triggering signal, and generating an illumination modulation signal; and an illumination modulation signal processing circuit configured for receiving the illumination modulation signal and processing the illumination modulation signal to generate one of a rough modulation controlling signal to modulate illumination of the backlight source in a large range and a fine modulation controlling signal to modulate the illumination of the backlight source in a small range; wherein the illumination modulation signal processing circuit comprises a first integrating and smoothing circuit, a reversing circuit, a pulse width modulation filter circuit, a second integrating and smoothing circuit, a summing circuit, an amplifying circuit, a selecting circuit, and a counting and comparing circuit, the first integrating and smoothing circuit, the reversing circuit, and the summing circuit are electrically connected in series; the pulse width modulation filter circuit, the second integrating and smoothing circuit, and the summing circuit are electrically connected in series; the summing circuit, the amplifying circuit, and the selecting circuit are electrically connected in series; the pulse width modulation filter circuit are electrically connected to the counting and comparing circuit; and the counting and comparing circuit and the second integrating and smoothing circuit are connected to the selecting circuit.