Head-wearable display with collimated light source and beam steering mechanism

• US 9,335,548 B1
• Filed: 08/21/2013
• Issued: 05/10/2016
• Est. Priority Date: 08/21/2013
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Cakmakci, Ozan, Gupta, Anurag
• Primary Examiner(s): Cerullo, Liliana
• Application Number:
  US13/972,782
• Time in Patent Office: 993 Days
• US Class Current: 1/1
• CPC Class Codes: G02B 26/005 based on electrowetting
• CPC Class Codes: G02B 27/0093 with means for monitoring data relating to the user, e.g. head-tracking, eye-tracking
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G06F 3/013 Eye tracking input arrangements G06F3/015 takes precedence
• CPC Class Codes: G06F 3/017 Gesture based interaction, e.g. based on a set of recognized hand gestures interaction based on gestures traced on a digitiser G06F3/04883

Abstract

A head-wearable display includes a collimated light source, a beam steering mechanism, and a synchronization controller. The collimated light source selectively emits collimated light. The beam steering mechanism is optically coupled to receive the collimated light and angularly scans the collimated light between beam steering states that each redirect the collimate light to a different angular direction along at least one angular dimension. The beam steering mechanism is coupled to scan the collimated light across an eyebox. The synchronization controller is coupled to the collimated light source and the beam steering mechanism to synchronize selective emission of the collimated light from the collimated light source with the beam steering states of the beam steering mechanism to repetitiously draw an image in the eyebox.

Claims

1. An apparatus for a head-wearable display, comprising:

a collimated light source coupled to selectively emit collimated light, wherein the collimated light source comprises a pixelated light source that generates a two-dimensional (“

2D”

) array of collimated light pixels;

a beam steering mechanism optically coupled to receive the collimated light as the 2D array of collimated light pixels emitted from the collimated light source and to angularly scan the 2D array of collimated light pixels between beam steering states that each redirect the 2D array of collimated light pixels to a different angular direction along at least one angular dimension, wherein the beam steering mechanism scans the 2D array of collimated light pixels across an eyebox, wherein the beam steering mechanism bends the 2D array of collimated light pixels by a same angle at a given time for all collimated light pixels output from the collimated light source at the given time; and

a synchronization controller coupled to the collimated light source and the beam steering mechanism to synchronize selective emission of the collimated light from the collimated light source with the beam steering states of the beam steering mechanism to repetitiously draw an image in the eyebox.

2. The apparatus of claim 1, wherein the beam steering mechanism is coupled to angularly scan between beam steering states angularly separated along two dimensions.

3. The apparatus of claim 2, wherein the beam steering mechanism is coupled to raster scan through the steering states angularly separated along the two dimensions under the influence of the synchronization controller.

4. The apparatus of claim 1, further comprising:

an eye tracking camera positioned to capture an eye image of an eye within the eyebox,

wherein the synchronization controller is coupled to the eye tracking camera to determine a gazing direction based upon the eye image and to selectively enable the collimated light pixels only within a localized subset of the pixelated light source based upon the determined gazing direction, wherein the localized subset is less than all of the collimated light pixels within the pixelated light source.

5. The apparatus of claim 4, wherein the beam steering mechanism comprises a two-dimensional array of beam steering elements and wherein a subset of the beam steering elements localized about the gazing direction are enabled by the synchronization controller to angularly steer the collimated light pixels while the beam steering elements outside of the subset of the beam steering elements are disabled and do not angularly scan passing light.

6. The apparatus of claim 1, wherein the beam steering mechanism comprises:

a first layer having a first two-dimensional (“

2D”

) array of electrowetting prisms coupled to beam steer along a first angular axis; and

a second layer having a second 2D array of electrowetting prisms coupled to beam steer along a second angular axis orthogonal to the first angular axis.

7. The apparatus of claim 1, wherein the beam steering mechanism comprises a liquid crystal polarization grating.

8. The apparatus of claim 1, wherein the collimated light source and the beam steering mechanism are see-through such that a user can view ambient scene light through the collimated light source and the beam steering mechanism.

9. The apparatus of claim 1, wherein the collimated light source comprises:

a collimator including a two-dimensional (“

2D”

) array of micro-mirrors; and

a light source module including a 2D array of divergent light sources each optically aligned with a corresponding one of the micro-mirrors, wherein the light source module is disposed between the collimator and the beam steering mechanism such that divergent light emitted from the light source module towards the collimator is reflected back towards the beam steering mechanism through the light source module as collimated light pixels.

10. The apparatus of claim 1, wherein the collimated light source comprises:

a collimator including a two-dimensional (“

2D”

) array of transmissive micro-lenses; and

a light source module including a 2D array of divergent light sources each optically aligned with a corresponding one of the micro-mirrors, wherein the collimator is disposed between the light source module and the beam steering mechanism such that divergent light emitted from the light source module is collimated upon passing through the collimator to form collimated light pixels.

11. The apparatus of claim 1, wherein the collimated light source comprises:

a divergent light source coupled to generate divergent light;

a collimating lens positioned to collimate the divergent light into the collimated light;

a lightguide for guiding the collimated light received from the collimating lens; and

one or more emission pixels disposed along a surface of the lightguide, wherein the one or more emission pixels are coupled to the synchronization controller to selectively emit the collimated light in synch with the angularly scanning of the beam steering mechanism under the influence of the synchronization controller to draw the image in the eyebox.

12. The apparatus of claim 11, wherein the one or more emission pixels comprise one or more switchable Bragg gratings configured to selectively emit the collimated light from the lightguide along a direction that is substantially normal to the surface of the lightguide.

13. The apparatus of claim 12, wherein the lightguide comprises a planar lightguide, and wherein the head-wearable display further comprises:

a linear array of divergent light sources;

a linear array of collimating lenses; and

a two-dimensional array of emission pixels disposed along the surface of the planar lightguide.

14. The apparatus of claim 1, wherein the collimated light source comprises:

a two-dimensional (“

2D”

) pixelated array of divergent light sources; and

a collimator disposed in an optical path between the two-dimensional pixelated array of divergent light sources and the beam steering mechanism.

15. The apparatus of claim 14, wherein the collimator comprises one of a 2D array of micro-lenses or photonic crystals implementing a super-collimation effect.

16. A method of operation of a head-worn display, comprising:

selectively emitting collimated light as a two-dimensional (“

2D”

) array of collimated light pixels;

directing the 2D array of collimated light pixels through a beam steering mechanism positioned in front of an eye of a user;

angularly scanning the 2D array of collimated light pixels into an eyebox, wherein the 2D array of collimated light pixels is angularly scanned across beam steering states angularly separated along two dimensions, wherein the 2D array of collimated light pixels are bent by a same angle at a given time for all collimated light pixels output from the collimated light source at the given time when angularly scanned across the beam steering states; and

synchronizing the selective emission of the collimated light with the angular scanning of the collimated light to repetitiously draw the image in the eyebox.

17. The method of claim 16, wherein the collimated light is sequentially raster scanned between the beam steering states such that all the collimated light emitted during a given beam steering state is redirected by a common angle and each beam steering state is associated with a different angle.

18. The method of claim 17, further comprising:

capturing an eye image of an eye within the eyebox;

determining a gazing direction based upon the eye image; and

selectively enabling the collimated light pixels only within a localized subset of the collimated light pixels based upon the determined gazing direction, wherein the localized subset is less than all of the collimated light pixels.

19. The method of claim 18, further comprising:

enabling a subset of the beam steering elements within the beam steering mechanism localized about the gazing direction to angularly steer the collimated light pixels; and

disabling the beam steering elements outside of the subset of the beam steering elements such that those beam steering elements do not angularly scan ambient light.

20. A head-wearable display, comprising:

a see-through display including;

a collimated light source coupled to selectively emit collimated light as a two-dimensional (“

2D”

) array of collimated light pixels;

a beam steering mechanism optically coupled to receive the 2D array of collimated light pixels emitted from the collimated light source and to angularly scan the 2D array of collimated light pixels between beam steering states that each redirect the 2D array of collimated light pixels to a different angular direction spread across two angular dimensions, wherein the beam steering mechanism scans the 2D array of collimated light pixels across an eyebox, wherein the beam steering mechanism bends the 2D array of collimated light pixels by a same angle at a given time for all collimated light pixels output from the collimated light source at the given time; and

a synchronization controller coupled to the collimated light source and the beam steering mechanism to synchronize selective emission of the collimated light from the collimated light source with the beam steering states of the beam steering mechanism to repetitiously draw an image in the eyebox; and

a frame assembly to support the see-through display for wearing on a head of a user with the beam steering mechanism positioned in front of and facing an eye of the user.

21. The head-wearable display of claim 20, wherein the collimated light source comprises a pixelated light source that generates the two-dimensional (“

2D”

) array of collimated light pixels.

22. The head-wearable display of claim 21, further comprising:

an eye tracking camera positioned to capture an eye image of an eye within the eyebox,

wherein the synchronization controller is coupled to the eye tracking camera to determine a gazing direction based upon the eye image and to selectively enable the collimated light pixels only within a localized subset of the pixelated light source based upon the determined gazing direction, wherein the localized subset is less than all of the collimated light pixels within the pixelated light source.

23. The head-wearable display of claim 20, wherein the collimated light source comprises:

a collimator including a two-dimensional (“

2D”

) array of micro-mirrors; and

a light source module including a 2D array of divergent light sources each optically aligned with a corresponding one of the micro-mirrors, wherein the light source module is disposed between the collimator and the beam steering mechanism such that divergent light emitted from the light source module towards the collimator is reflected back towards the beam steering mechanism through the light source module as collimated light pixels.

24. The head-wearable display of claim 20, wherein the collimated light source comprises:

a collimator including a two-dimensional (“

2D”

) array of transmissive micro-lenses; and

a light source module including a 2D array of divergent light sources each optically aligned with a corresponding one of the micro-lenses, wherein the collimator is disposed between the light source module and the beam steering mechanism such that divergent light emitted from the light source module is collimated upon passing through the collimator to form collimated light pixels.

25. The head-wearable display of claim 20, wherein the collimated light source comprises:

a divergent light source coupled to generate divergent light;

a collimating lens positioned to collimate the divergent light into the collimated light;

a lightguide for guiding the collimated light received from the collimating lens; and

one or more emission pixels disposed along a surface of the lightguide, wherein the one or more emission pixels are coupled to the synchronization controller to selectively emit the collimated light in synch with the angularly scanning of the beam steering mechanism under the influence of the synchronization controller to draw the image in the eyebox.

26. An apparatus for a head-wearable display, comprising:

a collimated light source coupled to selectively emit collimated light, wherein the collimated light source comprises a pixelated light source that generates a two-dimensional (“

2D”

) array of collimated light pixels;

a beam steering mechanism optically coupled to receive the collimated light as the 2D array of collimated light pixels emitted from the collimated light source and to angularly scan the 2D array of collimated light pixels between beam steering states that each redirect the 2D array of collimated light pixels to a different angular direction along at least one angular dimension, wherein the beam steering mechanism scans the 2D array of collimated light pixels across an eyebox;

a synchronization controller coupled to the collimated light source and the beam steering mechanism to synchronize selective emission of the collimated light from the collimated light source with the beam steering states of the beam steering mechanism to repetitiously draw an image in the eyebox; and

an eye tracking camera positioned to capture an eye image of an eye within the eyebox,

wherein the synchronization controller is coupled to the eye tracking camera to determine a gazing direction based upon the eye image and to selectively enable the collimated light pixels only within a localized subset of the pixelated light source based upon the determined gazing direction, wherein the localized subset is less than all of the collimated light pixels within the pixelated light source.

27. A method of operation of a head-worn display, comprising:

selectively emitting collimated light as a two-dimensional (“

2D”

) array of collimated light pixels;

directing the 2D array of collimated light pixels through a beam steering mechanism positioned in front of an eye of a user;

angularly scanning the 2D array of collimated light pixels into an eyebox, wherein the 2D array of collimated light pixels is angularly scanned across beam steering states angularly separated along two dimensions;

synchronizing the selective emission of the collimated light with the angular scanning of the collimated light to repetitiously draw an image in the eyebox;

capturing an eye image of an eye within the eyebox;

determining a gazing direction based upon the eye image; and

selectively enabling the collimated light pixels only within a localized subset of the collimated light pixels based upon the determined gazing direction, wherein the localized subset is less than all of the collimated light pixels.