Method to Autofocus on Near-Eye Display

• US 20130088413A1
• Filed: 10/05/2011
• Published: 04/11/2013
• Est. Priority Date: 10/05/2011
• Status: Abandoned Application

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Raffle, Hayes Solos, Wong, Adrian, Miao, Xiaoyu
• Application Number:
  US13/253,419
• Publication Number:
  US 20130088413A1
• Time in Patent Office: Days
• US Class Current: 345/7
• CPC Class Codes: G02B 2027/0127 comprising devices increasing the depth of field
• CPC Class Codes: G02B 27/0101 characterised by optical features G02B27/0172 takes precedence
• CPC Class Codes: G02B 7/005 Motorised alignment
• CPC Class Codes: G09G 2340/14 Solving problems related to the presentation of information to be displayed
• CPC Class Codes: G09G 2354/00 Aspects of interface with display user
• CPC Class Codes: G09G 3/003 to produce spatial visual effects

Abstract

An optical system has an aperture through which virtual and real-world images are viewable along a viewing axis. The optical system may be incorporated into a head-mounted display (HMD). By modulating the length of the optical path along an optical axis within the optical system, the virtual image may appear to be at different distances away from the HMD wearer. The wearable computer of the HMD may be used to control the length of the optical path. The length of the optical path may be modulated using, for example, a piezoelectric actuator or stepper motor. By determining the distance to an object with respect to the HMD using a range-finder or autofocus camera, the virtual images may be controlled to appear at various distances and locations in relation to the target object and/or HMD wearer.

Claims

1. A head-mounted display (HMD), comprising:

a head-mounted support;

at least one optical system attached to the head-mounted support, wherein the at least one optical system comprises;

a. a display panel configured to generate a light pattern;

b. an image former configured to form a virtual image from the light pattern generated by the display panel;

c. a viewing window configured to allow outside light in from a real-world environment of the optical system;

d. a proximal beam splitter through which the outside light and the virtual image are viewable along a viewing axis;

e. a distal beam splitter optically coupled to the display panel and the proximal beam splitter; and

f. an optical path length modulator configured to adjust an optical path length between the display panel and the image former; and

an autofocus camera configured to image the real-world environment to obtain an autofocus signal; and

a computer, wherein the computer is configured to control the display panel and the optical path length modulator based on the autofocus signal.

2. The head-mounted display of claim 1, wherein the optical path length modulator comprises a voice coil actuator.

3. The head-mounted display of claim 1, wherein the optical path length modulator comprises a stepper motor actuator.

4. The head-mounted display of claim 1, wherein the optical path length modulator comprises a piezoelectric motor.

5. The head-mounted display of claim 1, wherein the optical path length modulator comprises a microelectromechanical system (MEMS) actuator.

6. The head-mounted display of claim 1, wherein the optical path length modulator comprises a shape memory alloy.

7. The head-mounted display of claim 1, wherein the optical path length modulator comprises an electrical-thermal polymer actuator.

8. The head-mounted display of claim 1, wherein the autofocus camera further comprises a range-finder.

9. The head-mounted display of claim 1, wherein the autofocus camera further comprises a passive autofocus mechanism.

10. The head-mounted display of claim 9, wherein the passive autofocus mechanism is configured to use a phase detection algorithm.

11. The head-mounted display of claim 9, wherein the passive autofocus mechanism is configured to use a contrast measurement algorithm.

12. The head-mounted display of claim 9, wherein the passive autofocus mechanism is configured to use an infrared or visible autofocus assist lamp.

13. The head-mounted display of claim 1, wherein the autofocus camera further comprises an active autofocus mechanism.

14. The head-mounted display of claim 13, wherein the active autofocus mechanism is configured to use an ultrasonic source and detector.

15. The head-mounted display of claim 13, wherein the active autofocus mechanism is configured to use an infrared source and detector.

16. A method, comprising:

receiving an autofocus signal from an autofocus camera wherein the autofocus signal is related to a target object in an environment of an optical system, wherein the optical system is configured to display virtual images formed by an image former from light patterns generated by a display panel;

selecting a virtual image; and

controlling the optical system based on the autofocus signal so as to display the selected virtual image at an apparent distance related to the target object.

17. The method of claim 16, wherein the optical system comprises an opaque display.

18. The method of claim 16, wherein the optical system comprises a see-through display.

19. The method of claim 18, wherein the optical system further comprises a viewing window configured to allow outside light in from the environment of the optical system.

20. The method of claim 19, wherein the optical system further comprises a proximal beam splitter through which outside light and virtual images are viewable along a viewing axis.

21. The method of claim 20, wherein the optical system further comprises a distal beam splitter optically coupled to the display panel and the proximal beam splitter.

22. The method of claim 16, wherein receiving an autofocus signal from an autofocus camera further comprises obtaining a range to the target object using a range-finder.

23. The method of claim 16, wherein controlling the optical system based on the autofocus signal further comprises adjusting an optical path length between the display panel and the image former.

24. The method of claim 23, wherein adjusting an optical path length comprises controlling an optical path length modulator.

25. The method of claim 16, wherein the selected virtual image relates to the target object.

26. A non-transitory computer readable medium having stored therein instructions executable by a computing device to cause the computing device to perform functions, comprising:

receiving an autofocus signal from an autofocus camera wherein the autofocus signal is related to a target object in an environment of an optical system, wherein the optical system is configured to display virtual images formed by an image former from light patterns generated by a display panel;

selecting a virtual image; and

controlling the optical system based on the autofocus signal so as to display the selected virtual image at an apparent distance related to the target object.

27. The non-transitory computer readable medium of claim 26, wherein the optical system comprises an opaque display.

28. The non-transitory computer readable medium of claim 26, wherein the optical system comprises a see-through display.

29. The non-transitory computer readable medium of claim 26, wherein controlling the optical system based on the autofocus signal further comprises adjusting an optical path length between the display panel and the image former.

30. The non-transitory computer readable medium of claim 29, wherein adjusting an optical path length comprises controlling an optical path length modulator.