Static uniformity correction for a scanning projector performing consecutive non-linear scan with multi-ridge light sources

Patent metadata

Field	Value
Publication number	US-12546992-B2
Application number	US-202318130550-A
Country	US
Kind code	B2
Filing date	Apr 4, 2023
Priority date	Apr 4, 2023
Publication date	Feb 10, 2026
Grant date	Feb 10, 2026

Abstract

Static non-uniformity effects in a coherent biresonant scanning projector are mitigated through correction factors for pulse events during one frame time. According to an analytical approach, a set of input parameters such as scan angle, micro-electromechanical system (MEMS) obliquity, ridge spacing, etc. are used to optimize color-wise luminance uniformity. According to an optimization approach, pulse correction factors are determined using a custom-defined cost function that attempts to optimize for both luminance and color uniformity.

First claim

The invention claimed is:

1 . An apparatus, comprising:
a multi-emitter light source to provide a light beam; a two-dimensional (2D) beam scanner optically coupled to the light source, the two-dimensional (2D) beam scanner to:
receive the light beam; and
generate a light field by performing a biresonant scan of the light beam; and
a controller communicatively coupled to the light source and the beam scanner, the controller to:
cause the beam scanner to scan the light beam about a first axis and a second axis within a field of view (FOV) following a consecutive non-linear pattern;
determine a correction factor for each firing of each emitter of the light source for each frame of an image generated by the scanned light beam; and
utilize the determined correction factor for each firing of each emitter of the light source.

2 . The apparatus of claim 1 , wherein the light source is a multi-ridge light source, and ridges of the multi-ridge light source are aligned horizontally or vertically.

3 . The apparatus of claim 2 , wherein the correction factor is determined based on at least one of a local painting velocity vector, a brush-width, a skip, a location within the FOV, or time.

4 . The apparatus of claim 3 , wherein the brush-width is a number of ridges of the multi-ridge light source multiplied by a vector connecting two adjacent ridges, and the skip is a vertical displacement for the ridges of the multi-ridge light source.

5 . The apparatus of claim 2 , wherein the correction factor is a number between 0 and 1, and correction factors for each emitter are stored in a memory as a correction factor map.

6 . The apparatus of claim 2 , wherein correction factors for consecutive firing events are stored as a vector.

7 . The apparatus of claim 1 , wherein the controller is to determine the correction factor by:
determining a vertical brightness uniformity correction factor; determining a horizontal brightness uniformity correction factor; and multiplying the vertical brightness uniformity correction factor and the horizontal brightness uniformity correction factor.

8 . The apparatus of claim 1 , wherein the controller is to determine the correction factor by:
identifying a loss function for all color channels based on an intra-pixel variance of color content and a variation of brightness from a target brightness; identifying a gradient for all color channels; and applying an optimization technique to the loss function and the gradient.

9 . The apparatus of claim 8 , wherein the controller is further to:
prioritize at least one of the loss function or the gradient over each other by employing at least one weight factor.

10 . The apparatus of claim 1 , wherein the consecutive non-linear pattern is a coherent Lissajous pattern.

11 . The apparatus of claim 1 , wherein the beam scanner is a micro-electromechanical system (MEMS) scanner, and the beam scanner is to paint the FOV larger than a FOV of the image generated by the scanned light beam.

12 . A near-eye display device, comprising:
a waveguide to provide an image on an eye box; a projector optically coupled to the waveguide, the projector comprising:
a multi-ridge light source to provide a light beam, wherein ridges of the light source are aligned horizontally, vertically, or at an angle;
a two-dimensional (2D) beam scanner optically coupled to the multi-ridge light source, the 2D beam scanner to:
receive the light beam; and
generate a light field by performing a biresonant scan of the light beam; and

a controller communicatively coupled to the multi-ridge light source and the beam scanner, the controller to:
cause the beam scanner to scan the light beam about a first axis and a second axis within a field of view (FOV) following a consecutive non-linear pattern;
determine a correction factor for each firing of each emitter of the light source for each frame of an image generated by the scanned light beam; and
utilize the determined correction factor for each firing of each emitter of the light source.

13 . The near-eye display device of claim 12 , wherein
the correction factor is determined based on at least one of a local painting velocity vector, a brush-width, a skip, a location within the FOV, or time, and the brush-width corresponds to a number of ridges of the multi-ridge light source multiplied by a vector connecting two adjacent ridges, and the skip corresponds to a vertical displacement for the ridges of the multi-ridge light source.

14 . The near-eye display device of claim 12 , wherein
the correction factor is a number between 0 and 1, and correction factors for each emitter are stored in a memory as a correction factor map, or correction factors for consecutive firing events are stored as a vector.

15 . The near-eye display device of claim 12 , wherein the controller is to determine the correction factor by:
determining a vertical brightness uniformity correction factor; determining a horizontal brightness uniformity correction factor; and multiplying the vertical brightness uniformity correction factor and the horizontal brightness uniformity correction factor.

16 . The near-eye display device of claim 12 , wherein the controller is to determine the correction factor by:
identifying a loss function for all color channels based on an intra-pixel variance of color content and a variation of brightness from a target brightness; identifying a gradient for all color channels; and applying an optimization technique to the loss function and the gradient.

17 . A method, comprising:
generating a light beam at a multi-ridge light source of a scanning projector, wherein a distance between ridges of the multi-ridge light source is larger than one pixel and the ridges are aligned horizontally, vertically, or at an angle; scanning the light beam, at a two-dimensional (2D) beam scanner, about a first axis and a second axis within a field of view (FOV) following a coherent Lissajous pattern in a biresonant manner; generating a light field on an eye box, by a waveguide, to provide an image to a viewer through the eye box; determining a correction factor for each firing of each emitter of the light source for each frame of an image generated by the scanned light beam; and utilizing the determined correction factor for each firing of each emitter of the light source.

18 . The method of claim 17 , further comprising:
determining the correction factor based on at least one of a local painting velocity vector, a brush-width, a skip, a location within the FOV, or time, wherein the brush-width corresponds to a number of ridges of the multi-ridge light source multiplied by a vector connecting two adjacent ridges, and the skip corresponds to a vertical displacement for the ridges of the multi-ridge light source.

19 . The method of claim 17 , further comprising:
determining the correction factor by:
identifying a loss function for all color channels based on an intra-pixel variance of color content and a variation of brightness from a target brightness;
identifying a gradient for all color channels; and
applying an optimization technique to the loss function and the gradient.

20 . The method of claim 17 , further comprising:
storing correction factors for a single emitter in a memory as a correction factor map; or storing correction factors for consecutive firing events as a vector.

Assignees

• Meta Platforms Tech Llc

Inventors

• Greif Daniel Guenther
• Wheelwright Brian
• Kehs Zachary

Classifications

• G02B26/10 Primary

  Scanning systems · CPC title

• G02B2027/0112

  comprising device for genereting colour display · CPC title

• G02B2027/0118

  comprising devices for improving the contrast of the display / brillance control visibility · CPC title

• G02B2027/0178

  Eyeglass type (eyeglass details G02C) · CPC title

• 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