METHOD TO REDUCE RF NOISE GENERATION AND REQUIRED PEAK LASER OUTPUT IN RASTER SCAN PORTABLE PROJECTORS

摘要

A method and apparatus that projects a two-dimensional image is disclosed. The method may include emitting a laser beam, sweeping the laser beam with a first scan mirror along a first scan direction to form a scan line on the projection surface, and sweeping the scan line with a second scan mirror along a second scan direction generally orthogonal to the first scan direction to form a raster pattern of scan lines on the projection surface. The scanner for the first scan mirror is driven with a stimulus waveform, wherein the stimulus waveform has a fundamental frequency that is substantially equal to the resonance frequency of the scanner but also contains harmonics to achieve a nearly constant velocity of the laser beam spot during its scan across the projection surface. The stimulus thereby reduces peak laser output power and corresponding noise generation while maintaining image brightness and image quality.