Scanned light beam display with brightness compensation

• US 7,612,737 B2
• Filed: 03/28/2006
• Issued: 11/03/2009
• Est. Priority Date: 04/09/2001
• Status: Active Grant

• Current Assignee: Microvision, Inc.
• Original Assignee: Microvision, Inc.
• Inventors: Urey, Hakan, Straka, Scott W., Bright, Gregory Scott, Moore, James G., Tegreene, Clarence T., Lewis, John R., Black, Philip C.
• Primary Examiner(s): Abdulselam; Abbas I
• Application Number:
  US11/393,161
• Publication Number:
  US 20060164330A1
• Time in Patent Office: 1,316 Days
• Field of Search: 345/7, 345/204, 345/32, 345/77, 345/214, 345/505, 345/589, 345/593, 345/690, 348/68, 348/500, 348/51, 348/742, 348/750, 250/363.02, 250/205, 347/225, 347/230, 347/232, 359/201.1, 359/242, 359/462, 359/630, 358/505
• US Class Current: 345/32
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G09G 3/001 using specific devices not provided for in groups G09G3/02 - G09G3/36, e.g. using an intermediate record carrier such as a film slide; Projection systems; Display of non-alphanumerical information, solely or in combination with alphanumerical information, e.g. digital display on projected diapositive as background slide projectors per se G03B23/00 = 42 HP
• CPC Class Codes: G09G 3/025 with scanning or deflecting the beams in two directions or dimensions
• CPC Class Codes: H04N 3/08 having a moving reflector
• CPC Class Codes: H04N 5/04 Synchronising for television systems using pulse code modulation H04N7/56
• CPC Class Codes: H04N 5/06 Generation of synchronising signals
• CPC Class Codes: H04N 5/126 whereby the synchronisation signal indirectly commands a frequency generator
• CPC Class Codes: H04N 9/3132 using one-dimensional electronic spatial light modulators
• CPC Class Codes: H04N 9/641 Multi-purpose receivers, e.g. for auxiliary information H04N9/642 takes precedence

Abstract

A scanned beam display is operable to compensate for variations in apparent pixel brightness arising from variations in beam scanning velocity and/or pixel dwell times. A compensation circuit modifies pixel values according to their scanning velocity and/or dwell time.

Claims

1. A method for correcting the brightness of pixels in a displayed image in a scanned light display having a non-uniform light scanning velocity, comprising the steps of:

receiving a pixel brightness multiplier;

determining a pixel dwell time for a scanned beam of light;

determining a corrected pixel brightness as a function of the pixel brightness multiplier and the pixel dwell time, wherein the step of determining a corrected pixel brightness as a function of the pixel brightness multiplier and the pixel dwell time includes determining the pixel brightness multiplier as a function of gamma; and

outputting a signal corresponding to the corrected pixel brightness.

2. A method for correcting the brightness of pixels in a displayed image in a scanned light display having a non-uniform light scanning velocity, comprising the steps of:

receiving a pixel brightness multiplier;

determining a pixel dwell time for a scanned beam of light, wherein the step of determining a pixel dwell time includes selecting an approximate pixel dwell time, and wherein the step of selecting an approximate pixel dwell time includes selecting an approximate pixel dwell time from a group of approximate pixel dwell times as a function of the pixel position along a dimension scanned by the beam of light;

wherein the number of groups of approximate pixel dwell times is less than the number of pixels along the dimension scanned by the beam of light;

determining a corrected pixel brightness as a function of the pixel brightness multiplier and the pixel dwell time; and

outputting a signal corresponding to the corrected pixel brightness.

3. The method of claim 2 wherein the approximate pixel dwell times within a group are non-constant.

4. The method of claim 2 wherein:

each of the groups of approximate pixel dwell times includes a linear function of pixel position;

each linear function forms a spline with at least one other group of approximate pixel dwell times; and

the step of selecting an approximate pixel dwell time includes fitting the pixel position to the linear function.

5. The method of claim 4 wherein the splines together include a fit to a actual pixel dwell times as a function of pixel position.

6. A method for correcting the brightness of pixels in a displayed image in a scanned light display having a non-uniform light scanning velocity, comprising the steps of:

receiving a pixel brightness multiplier;

determining a pixel dwell time for a scanned beam of light;

determining a corrected pixel brightness as a function of the pixel brightness multiplier and the pixel dwell time; and

outputting a signal corresponding to the corrected pixel brightness, wherein the step of outputting a signal corresponding to the corrected pixel brightness further comprises;

driving a digital-to-analog converter to produce an analog pixel voltage;

amplifying the analog pixel voltage to produce a drive voltage; and

driving a light emitter with the drive voltage to produce emitted pixel light corresponding to the corrected pixel brightness.

7. The method of claim 6 further comprising the steps of:

transmitting the emitted pixel light to a scanner; and

reflecting the emitted pixel light at an angle corresponding to the pixel position.

8. A method for correcting the brightness of pixels in a displayed image in a scanned light display having a non-uniform light scanning velocity, comprising the steps of:

receiving a pixel brightness multiplier;

determining a pixel dwell time for a scanned beam of light;

determining a corrected pixel brightness as a function of the pixel brightness multiplier and the pixel dwell time; and

outputting a signal corresponding to the corrected pixel brightness;

repeating the steps of;

receiving the pixel brightness multiplier;

determining a pixel dwell time for a scanned beam of light;

determining a corrected pixel brightness as a function of the pixel brightness multiplier and the pixel dwell time;

driving a digital-to-analog converter to produce an analog pixel voltage;

amplifying the analog pixel voltage to produce a drive voltage;

driving a light emitter with the drive voltage to produce emitted pixel light corresponding to the corrected pixel brightness;

transmitting the emitted pixel light to a scanner; and

reflecting the emitted pixel light at an angle corresponding to the pixel position to produce a brightness-corrected displayed image.

9. The method of claim 8 wherein driving a light emitter includes driving a plurality of light emitters operable to emit a corresponding plurality of wavelengths;

and

wherein the plurality of light emitters are operable to produce a color displayed image.

10. A method for correcting the brightness of pixels in a displayed image in a scanned light display having a non-uniform light scanning velocity, comprising the steps of:

receiving a pixel brightness multiplier;

determining a pixel dwell time for a scanned beam of light;

determining a corrected pixel brightness as a function of the pixel brightness multiplier and the pixel dwell time, wherein the step of determining a corrected pixel brightness includes determining a gamma correction; and

outputting a signal corresponding to the corrected pixel brightness.

11. A scanned beam video display comprising:

an interface to receive a video image;

a correction processor coupled to the interface, the correction processor to modify pixel values in the received video image to compensate for variable pixel dwell time and produce a compensated video image comprising the compensated pixel values;

at least one light emitter;

an electronic drive circuit coupled to the correction processor and the at least one light emitter, the electronic drive circuit to drive the at least one light emitter to emit at least one compensated beam of light; and

a beam sweep mechanism to sweep the compensated beam of light over a field of view at a variable angular velocity to form a displayed video image formed from pixels having a variable dwell time.

12. The scanned beam video display of claim 11 wherein the beam sweep mechanism includes a beam scanner aligned to receive the at least one compensated beam of light and reflect the compensated beam of light toward the field of view.

13. The scanned beam video display of claim 11 wherein the beam scanner scans resonantly in at least one dimension.

14. The scanned beam video display of claim 11 wherein the beam scanner includes a MEMS scanner.

15. The scanned beam video display of claim 14 wherein the correction processor modifies the pixel values in the received video image to compensate for optical loss in the relay optics.

16. The scanned beam video display of claim 14 wherein the correction processor modifies the pixel values in the received video image to compensate for chromatic variation in the relay optics.

17. The scanned beam video display of claim 14 wherein the correction processor applies gamma correction to the pixel values in the received video image to produce a gamma-corrected video image.

18. The scanned beam video display of claim 11 further comprising relay optics to relay the swept compensated beam of light toward the field of view.

19. A method for displaying an image with a scanned beam display comprising the steps of:

receiving an image comprised of pels;

for a plurality of pels in the received image, determining a corresponding beam scanning velocity, wherein the step of determining a corresponding beam scanning velocity includes selecting an approximate beam scanning velocity from a group of approximate beam scanning velocities as a function of the pel position along a dimension scanned by the beam of light;

wherein the number of groups of approximate beam scanning velocities is less than the number of pels along the dimension scanned by the beam of light; and

modifying the values of the plurality of pels to produce compensated pel values corresponding to the beam scanning velocity.