Projection System with Multi-Phased Scanning Trajectory

• US 20080144150A1
• Filed: 02/18/2008
• Published: 06/19/2008
• Est. Priority Date: 05/17/2002
• Status: Active Grant

• Current Assignee: Microvision, Inc.
• Original Assignee: Microvision, Inc.
• Inventors: Freeman, Mark O., Brown, Margaret K., Champion, Mark
• Granted Patent: US 8,446,342 B2
• Time in Patent Office: Days
• US Class Current: 359/199
• CPC Class Codes: G09G 3/025 with scanning or deflecting the beams in two directions or dimensions
• CPC Class Codes: G09G 5/18 Timing circuits for raster scan displays specially adapted for television H04N ; synchronisation between the display unit and other display units, videodisc player G09G5/12

Abstract

A scanned beam display device scans a beam to paint an image. The beam is scanned in two dimensions and includes at least one sinusoidal component. Phase offsets are introduced to provide different scan trajectories for successive traversals of the image field of view.

Claims

1. A scanned beam display system comprising:

a scanning mirror to deflect a beam in response to electrical stimuli; and

a driver circuit to produce the electrical stimuli, wherein the electrical stimuli causes the beam to be deflected in a sinusoidal horizontal trajectory having a first period (T_H), and a vertical trajectory having a second period (T_V), wherein the second period is a non-integer multiple of the first period.

2. The scanned beam display system of claim 1 wherein the vertical trajectory is a sawtooth trajectory.

3. The scanned beam display system of claim 1 wherein the vertical trajectory is a triangular trajectory.

4. The scanned beam display system of claim 1 wherein the vertical trajectory is a sinusoidal trajectory.

5. The scanned beam display system of claim 1 wherein a ratio of the second period to the first period (T_V/T_H) is equal to (n+½

) where n is an integer.

6. The scanned beam display system of claim 1 wherein a ratio of the second period to the first period (T_V/T_H) is equal to (n+⅓

) where n is an integer.

7. The scanned beam display system of claim 1 wherein a ratio of the second period to the first period (T_V/T_H) is equal to (n+1/x) where n and x are integers.

8. The scanned beam display system of claim 1 further comprising at least one laser light source to emit the beam.

9. The scanned beam display system of claim 8 further comprising image processing circuitry to drive the at least one laser light source, wherein the image processing circuitry is operable to interpolate between pixel data in an image to determine pixel data to be displayed.

10. The scanned beam display system of claim 1 wherein the electrical stimuli are responsive to a sync signal representing a resonant frequency of the mirror.

11. A scanned beam projection apparatus comprising:

means for deflecting a visible light beam to create a scanned beam having a horizontal trajectory and a vertical trajectory; and

means for creating control signals to drive the means for deflecting, the control signals determining the horizontal and vertical trajectories;

wherein the vertical trajectory has a first fundamental frequency, and the horizontal trajectory is sinusoidal and has a second fundamental frequency that is a non-integer multiple of the first fundamental frequency.

12. The scanned beam projection apparatus of claim 11 wherein the means for deflecting a visible light beam comprises a mirror.

13. The scanned beam projection apparatus of claim 12 further comprising at least one laser light source to produce the visible light beam.

14. A scanned beam projection system comprising:

at least one laser light source to produce a visible beam;

a micro-electronic machine (MEMS) mirror to deflect the visible beam in a scan trajectory that includes a sinusoidal horizontal trajectory and a vertical trajectory; and

driver circuitry to provide at least one drive signal to the MEMS mirror to provide a non-zero phase shift in the sinusoidal horizontal trajectory for successive vertical trajectories.

15. The scanned beam projection system of claim 14 wherein the vertical trajectory is linear.

16. The scanned beam projection system of claim 14 wherein the vertical trajectory is sinusoidal.

17. The scanned beam projection system of claim 14 wherein the non-zero phase shift is substantially 180 degrees.

18. The scanned beam projection system of claim 14 further comprising image processing circuitry to drive the at least one laser light source to cause pixels to be displayed along the scan trajectory.

19. The scanned beam projection system of claim 18 wherein the image processing circuit is operable to cause pixels to be displayed during horizontal trajectory sweeps from left-to-right and right-to-left.

20. The scanned beam projection system of claim 18 wherein the image processing circuit is operable to cause pixels to be displayed during vertical trajectories from top-to-bottom and bottom-to-top.

21. A mobile device comprising:

a communications transceiver; and

a projection apparatus that includes a micro-electronic machine (MEMS) mirror to deflect a laser light beam in two dimensions to repeatedly traverse an image field of view and paint pixels, wherein a phase offset is introduced on each traversal to cause different scan trajectories on successive traversals.

22. The mobile device of claim 21 wherein the phase offset is substantially 180 degrees.

23. A method comprising:

scanning a light beam on a first trajectory that includes a sinusoidal pattern in a first dimension while sweeping the light beam in a second dimension orthogonal to the first dimension; and

scanning the light beam on a second trajectory offset from the first trajectory in the first dimension.

24. The method of claim 23 further comprising modulating the light beam to display pixels on the first and second trajectories.

25. The method of claim 23 wherein scanning the light beam on the first trajectory and the second trajectory comprises driving a micro-electronic machine (MEMS) device with a sinusoidal horizontal deflection signal having a first period, and a vertical deflection signal having a second period that is a non-integer multiple of the first period.