Driving scanning projector display with pulses shorter than pixel duration

Patent metadata

Field	Value
Publication number	US-11025871-B1
Application number	US-201916414397-A
Country	US
Kind code	B1
Filing date	May 16, 2019
Priority date	Apr 4, 2019
Publication date	Jun 1, 2021
Grant date	Jun 1, 2021

Abstract

A driver for powering a pulsed light source of a scanning projector display is configured to provide a succession of powering electric pulses to the light source. Duration of the powering electric pulses is less than a pixel time interval during which a scanner of the projector display is directing the light beam to form a corresponding pixel of the image to be displayed. The amplitude of the powering electric pulses is proportionally higher, such that the light pulse has a pulse energy similar to the light energy provided by the light source when continuously driven through the pixel time interval. This enables the light source to be operated at a steeper portion of the electro-optical transfer curve, thereby improving the wall plug efficiency of the scanning projector display.

First claim

What is claimed is:

1. A driver for providing a succession of powering electric pulses to a light source for providing a light beam comprising a succession of light pulses corresponding to the succession of powering electric pulses;
wherein the light beam is coupled to a scanning projector display for rastering an image comprising a plurality of pixels by scanning the light beam to provide the image pixel-by-pixel, each light pulse of the succession of light pulses corresponding to a particular pixel of the plurality of pixels, wherein a duration of a powering electric pulse of the succession of powering electric pulses is less than a pixel time interval during which a scanner of the scanning projector display is directing the light beam to form a single pixel of the image; and
wherein the driver is configured to control energy of the light pulses for displaying the image by controlling an amplitude of the powering electric pulses.

2. The driver of claim 1 , configured to provide the powering electric pulses having an amplitude such that a pulse energy of light pulses provided by the light source when driven by the powering electric pulses is equal to an energy of the light beam when the light source is driven at a constant driving current during the entire pixel time interval to provide a pixel of a pre-defined brightness.

3. The driver of claim 1 , wherein a pulsewidth of the powering electric pulses is no greater than one third of the pixel time interval.

4. The driver of claim 3 , wherein the driver is configured to provide the powering electric pulses in a middle of the corresponding pixel time intervals during which a scanner of the scanning projector display is directing the light beam to the corresponding pixels of the image.

5. A scanning projector display comprising:
a light source for providing a light beam comprising a succession of light pulses;
a driver operably coupled to the light source for providing a succession of powering electric pulses to the light source to provide the succession of light pulses thereby;
a scanner optically coupled to the light source for scanning the light beam for rastering an image comprising a plurality of pixels by scanning the light beam to provide the image pixel-by-pixel, each light pulse of the succession of light pulses corresponding to a particular pixel of the plurality of pixels; and
a controller operably coupled to the scanner and the driver and configured for operating the driver, wherein durations of the powering electric pulses are less than a pixel time interval during which the scanner is directing the light beam to form a single pixel of the image;
wherein the driver is configured to control energy of the light pulses for displaying the image by controlling an amplitude of the powering electric pulses.

6. The scanning projector display of claim 5 , wherein the light source comprises at least one of a single-mode light source or a multimode light source.

7. The scanning projector display of claim 6 , wherein the light source comprises at least one of a side-emitting laser diode, a vertical-cavity surface-emitting laser diode, a superluminescent light-emitting diode, or a light-emitting diode.

8. The scanning projector display of claim 5 , wherein pulse energy of the powering electric pulses is lower than a threshold energy equal to the pixel time interval multiplied by a threshold power.

9. The scanning projector display of claim 8 , wherein the light source comprises a superluminescent LED (SLED), wherein the threshold power is a lasing threshold electric power of the SLED.

10. The scanning projector display of claim 5 , wherein a pulsewidth of the powering electric pulses is less than 10 nanoseconds.

11. The scanning projector display of claim 10 , wherein a pulsewidth of the powering electric pulses is less than 5 nanoseconds.

12. The scanning projector display of claim 5 , wherein the driver is configured to provide the powering electric pulses in a middle of the corresponding pixel time intervals during which a scanner of the scanning projector display is directing the light beam to the corresponding pixels of the image.

13. The scanning projector display of claim 5 , further comprising a body supporting the light source, the driver the scanner, and the controller, wherein the body has a form factor of a pair of glasses.

14. The scanning projector display of claim 5 , wherein the light source comprises an array of superluminescent LEDs.

15. A method for displaying an image, the method comprising:
using a scanner to angularly scan a light beam for rastering the image, the light beam comprising a succession of light pulses, each pulse corresponding to a particular individual pixel of the image;
determining a pointing angle of the scanner;
in accordance with the determined pointing angle of the scanner, determining an energy of a light pulse to be emitted; and
energizing a light-emitting diode (LED) by providing a powering electric pulse to the LED, the powering electric pulse having an energy corresponding to the determined energy of the light pulse to be emitted;
wherein a duration of the powering electric pulse is less than a pixel time interval during which the scanner is directing the light beam to form a single pixel of the image;
wherein determining the energy of the light pulse to be emitted comprises determining an amplitude of the light pulse to be emitted.

16. The method of claim 15 , wherein determining the amplitude of the light pulse to be emitted comprises determining an amplitude of the powering electric pulse.

17. The method of claim 15 , wherein determining the amplitude of the light pulse to be emitted comprises determining a duration of the powering electric pulse.

18. The method of claim 15 , wherein the powering electric pulse is provided in a middle of the pixel time interval during which the scanner is directing the light beam to form the corresponding pixel of the image.

Assignees

• Facebook Tech Llc

Inventors

• Magoz Ziv
• Laudolff James
• Greif Daniel Guenther
• McEldowney Scott Charles

Classifications

• G02B26/101

  with both horizontal and vertical deflecting means, e.g. raster or XY scanners (colour television using laser beams scanning a display screen H04N9/3129) · CPC title

• G02B27/0093

  with means for monitoring data relating to the user, e.g. head-tracking, eye-tracking · CPC title

• G02B27/0172

  characterised by optical features · CPC title

• G03B21/2053

  Intensity control of illuminating light (controlled by video signal processing H04N5/74 or H04N9/31) · CPC title

• G03B21/2033

  LED or laser light sources · CPC title