Method and apparatus for controllably modulating a laser in a laser projection display
View Patent ↗A laser projection device suitable for displaying full color images is disclosed. The LPD includes a variety of techniques for modulating laser beams produced by one or more lasers with image data to controllably produce the image using a modified raster scan.
1. An arrangement for projecting an image on a projection surface comprising:
a red laser source for generating a red laser beam;
a blue laser source for generating a blue laser beam;
a green laser source for generating a green laser beam;
an acousto-optical modulator (AOM) for converting image data into acoustic signals for modulating one of the laser beams, the AOM including a crystal through which the one laser beam passes, and an acoustic transducer for converting the acoustic signals into acoustic waves in the crystal and operative for deflecting the one modulated laser beam modulated by the image data;
a controller for controllably energizing the laser sources that generate other of the laser beams to modulate the other laser beams to form modulated other laser beams,
a combiner for combining the modulated laser beams to form a composite beam;
a scanner for sweeping the composite beam to form a scan line having pixels arranged along one direction, and for sweeping the scan line along another direction generally orthogonal to the one direction to form a raster pattern of scan lines on the projection surface; and
the controller being operative to illuminate selected pixels on the scan lines to form the image on the projection surface.
2. The arrangement of claim 1 , wherein the scanner includes a pair of scan mirrors oscillatable about respective axes extending along both of the directions.
3. A method of projecting an image on a projection surface, comprising the steps of:
generating a red laser beam with a red laser source;
generating a blue laser beam with a blue laser source;
generating a green laser beam with a green laser source;
converting image data into acoustic signals by modulating only one of the laser beams, including only passing the one laser beam through a crystal and converting the acoustic signals into acoustic waves in the crystal and deflecting the modulated one laser beam modulated by the image data;
controllably energizing the light sources that generate other of the laser beams to modulate the other laser beams to form modulated, other laser beams,
combining the one and other, modulated beams to form a composite beam;
sweeping the composite beam to form a scan line having pixels arranged along one direction, and sweeping the scan line along another direction generally orthogonal to the one direction to form a raster pattern of scan lines on the projection surface; and
illuminating selected pixels on the scan lines to form the image on the projection surface.