Apparatus and method of employing combined switching and PWM dimming signals to control brightness of cold cathode fluorescent lamps used to backlight liquid crystal displays

摘要

An AC power supply system modulates a high frequency switching signal with a pulse width modulation (PWM) signal to produce a composite signal. The duty cycle of the PWM component of the composite signal is used to control the brightness of a cold cathode fluorescent lamp for backlighting a liquid crystal display.