Microsoft Corporation
Closed loop controller for laser beam scanning display with high tolerance to mirror resonance frequency variation

Abstract:

The techniques disclosed herein provide methods, devices, and systems to compensate the drive waveform to a slow-scan mirror in a laser beam scanning (LBS) display device. The slow-scan controller generates the drive waveform, which is combined with feedback and coupled to the input of a notch filter in the control loop. Ripple in the slow-scan mirror trajectory, which occurs as a consequence of mismatches between the notch frequency of the notch filter and the resonance of the slow-scan mirror, is effectively suppressed in real time by an adaptive notch compensator. Consequently, the described compensation scheme allows for relaxed notch filter design criteria with high tolerance and mitigation of ripple is achieved at reduced cost. The parameters, logic and blocks of the adaptive notch compensator scheme may be time-domain or frequency domain solutions that are implemented, in hardware, software or combinations thereof.