Microvision, Inc.

Michael Lee Schaaf

Margaret K Brown

Mark Alan Champion

Randall Brian Sprague

Bruce Rothaar

Robert James Jackson

Bin Xue

Heng Huang

Steve Holmes

Lifford McLauchlan

Clint Charles Rollins

Mehrube Mehrubeoglu

Gregory Schneider

The radiance of a laser diode is a function of laser diode drive current. The radiance is also a function of other factors, such as age and temperature. A laser projection device includes laser diodes to generate light in response to a commanded radiance, and also includes photodetectors to provide a measured radiance. The commanded radiance and measured radiance are compared, and drive currents for the laser diodes are adjusted to provide luminance and color balance tracking.

Laser projection white balance tracking

A scanning beam projection system includes a scanning mirror having a fast-scan axis and a slow-scan axis. Movement on the slow-scan axis is controlled by a slow-scan scanning mirror control system. The control system receives position information describing angular displacement of the mirror. An outer loop of the control system operates in the frequency domain and determines harmonic drive coefficients for a scanning mirror drive signal. An inner loop of the control system operates in the time domain and compensates for a scanning mirror resonant vibration mode at a frequency within the frequency band occupied by the harmonic drive coefficients.

Scanning mirror control

The temperature of a laser diode changes in response to video content across a line of a displayed image, and the radiance changes as a function of temperature. An adaptive model estimates the temperature of the laser diode based on prior drive current values. For each displayed pixel, diode drive current is determined from the estimated diode temperature and a desired radiance value. A feedback circuit periodically measures the actual temperature and updates the adaptive model.

Laser projection temperature compensation

Growing community of inventors

Bainbridge Island, WA, United States of America

Michael Lee Schaaf