Low-visual noise, jitterized pulse width modulation brightness control circuit

摘要

A low visual noise, jitterized pulse width modulation brightness control circuit is provided. The circuit uses a brightness control signal generating unit to receive a brightness adjusting signal and to generate a brightness control signal in response to the brightness adjusting signal. The brightness control pulse signal has a duty cycle or frequency varying in a predetermined range. An inverter coupled to the brightness control signal generating unit drives the fluorescent lamp in response to the brightness control pulse signal to reduce the visual interference due to the adjustment of the current beam density.