VARIFOCAL HEAD-MOUNTED DISPLAY INCLUDING MODULAR AIR SPACED OPTICAL ASSEMBLY

• US 20180203505A1
• Filed: 01/17/2017
• Published: 07/19/2018
• Est. Priority Date: 01/17/2017
• Status: Active Grant

• Current Assignee: META Platforms Technologies LLC (Meta Platforms, Inc. (f/k/a Facebook, Inc.))
• Original Assignee: Oculus VR, LLC (Meta Platforms, Inc. (f/k/a Facebook, Inc.))
• Inventors: Trail, Nicholas Daniel, Lanman, Douglas Robert
• Granted Patent: US 10,310,598 B2
• Time in Patent Office: Days
• CPC Class Codes: G02B 2027/0138 comprising image capture systems, e.g. camera
• CPC Class Codes: G02B 2027/014 comprising information/image processing systems
• CPC Class Codes: G02B 2027/0185 Displaying image at variable distance
• 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: G02C 7/081 Ophthalmic lenses with variable focal length
• CPC Class Codes: G06F 1/163 Wearable computers, e.g. on a belt
• CPC Class Codes: G06F 3/011 Arrangements for interaction with the human body, e.g. for user immersion in virtual reality blind teaching G09B21/00
• CPC Class Codes: G06F 3/013 Eye tracking input arrangements G06F3/015 takes precedence

Abstract

A head-mounted display (HMD) includes an electronic display configured to emit image light, an optical assembly that provides optical correction to the image light, an eye tracking system, and a varifocal module. The optical assembly includes a back optical element configured to receive the image light from the electronic display, and a coupling assembly configured to couple a front optical element to a location within the optical assembly such that the front optical element receives light transmitted by the back optical element. The optical correction is determined in part by an optical characteristic of the front optical element that is replaceable. The eye tracking system determines eye tracking information for a first eye of a user of the HMD. A varifocal module adjusts focus of images displayed on the electronic display, based on the eye tracking information and the optical correction.

Claims

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

an electronic display;

an optical assembly comprising a front optical element in series with a back optical element adjacent to the electronic display with an air gap between the front optical element and the back optical element, wherein the optical assembly is configured to change an optical characteristic of at least one of the front optical element and the back optical element;

an eye tracker configured to determine a position and orientation of a user'"'"'s eye based at least in part on the optical characteristic; and

a varifocal module configured to adjust focus of one or more images displayed on the electronic display, based on the determined position and orientation of the user'"'"'s eye and the optical characteristic.

2. The HMD of claim 1, wherein the front optical element is replaceable and selected from a set of optical elements, each optical element from the set having a different optical characteristic.

3. The HMD of claim 2, wherein each optical element from the set has a different optical prescription.

4. The HMD of claim 2, wherein the set of optical elements comprises spherical lenses with spherical optical powers of −

6, −

3, 0, and 3 diopters, and other lenses with the same spherical optical powers having additional diopters for astigmatism.

5. The HMD of claim 1, wherein the optical characteristic is a correction for astigmatism, and the front optical element is rotatable to align the front optical element within the optical assembly to compensate for astigmatism.

6. The HMD of claim 1, wherein the varifocal module is configured to adjust focus of the one or more images displayed on the electronic display by adjusting position of at least one of the electronic display, the front optical element and the back optical element.

7. The HMD of claim 1, wherein the eye tracker is positioned optically after reflection from the back optical element.

8. The HMD of claim 1, wherein the eye tracker is positioned optically folded between the front optical element and the back optical element.

9. The HMD of claim 1, wherein the back optical element comprises a first surface adjacent to the electronic display and a second surface opposite to the first surface configured to reflect light of a defined range of wavelengths, and the eye tracker comprises:

an illumination source positioned optically between the front optical element and the back optical element, the illumination source configured to illuminate the second surface of the back optical element with light having one or more wavelengths within the defined range of wavelengths;

an imaging device positioned optically between the front optical element and the back optical element, the imaging device configured to capture an image of the user'"'"'s eye illuminated with light emitted from the illumination source having the one or more wavelengths and reflected from the second surface of the back optical element; and

a controller coupled to the imaging device and the illumination source, the controller configured to;

determine the orientation of the user'"'"'s eye based on the captured image, and

adjust resolution of the one or more images displayed on the electronic display, based on the determined orientation of the user'"'"'s eye.

10. The HMD of claim 9, wherein the illumination source and the imaging device are positioned outside of a primary display optical path to the user'"'"'s eye.

11. The HMD of claim 9, wherein the second surface is coated to reflect light of the defined range of wavelengths and transmit visible light.

12. The HMD of claim 9, wherein the second surface is spherical, aspherical, consisting of a polynominal basis, or of a free-form.

13. The HMD of claim 9, wherein the imaging device is oriented to capture the image of the eye illuminated with the light reflected from the eye and then from the second surface of the back optical element.

14. The HMD of claim 1, wherein the front optical element is composed of a different material than the back optical element.

15. The HMD of claim 1, wherein the optical assembly further comprises at least one other optical element positioned in optical series with the front optical element and the back optical element.

16. A head-mounted display (HMD) comprising:

an electronic display configured to emit image light;

an optical assembly that provides optical correction to the image light, the optical assembly comprising;

a back optical element configured to receive the image light from the electronic display,

a coupling assembly, the coupling assembly configured to couple a front optical element to a location within the optical assembly such that it receives light transmitted by the back optical element, and that there is an air gap between the location and the back optical element, wherein the optical correction is determined in part by an optical characteristic of the optical assembly; and

an eye tracking system that determines eye tracking information for one or both eyes of a user of the HMD; and

a varifocal module configured to adjust focus of one or more images displayed on the electronic display, based on the eye tracking information and the optical correction.

17. The HMD of claim 16, wherein the varifocal module is configured to compensate for a difference between a prescription of the user and the optical characteristic of the optical assembly to provide the optical correction to the image light.

18. The HMD of claim 16, wherein the varifocal module is configured to adjust focus of the one or more images displayed on the electronic display by adjusting position of at least one of the electronic display, the front optical element and the back optical element, based on the eye tracking information and the optical correction.

19. The HMD of claim 16, wherein:

the front optical element is coupled, via the coupling assembly, to the location within the optical assembly; and

the front optical element is positioned in optical series with the back optical element adjacent to the electronic display.

20. The HMD of claim 19, wherein the front optical element is replaceable and selected from a set of optical elements, each optical element from the set having a different optical characteristic.

21. The HMD of claim 19, wherein the back optical element comprises a first surface adjacent to the electronic display and a second surface opposite to the first surface configured to reflect light of a defined range of wavelengths, and the eye tracking system comprises:

an illumination source positioned between the front optical element and the back optical element, the illumination source configured to illuminate the second surface of the back optical element with light having one or more wavelengths within the defined range of wavelengths;

an imaging device positioned between the front optical element and the back optical element, the imaging device configured to capture an image of the user'"'"'s eye illuminated with light emitted from the illumination source having the one or more wavelengths and reflected from the second surface of the back optical element; and

a controller coupled to the imaging device and the illumination source, the controller configured to determine the eye tracking information based on the captured image.

22. The HMD of claim 21, wherein:

the light having the one or more wavelengths reflected from the second surface of the back optical element comprises infra-red (IR) light; and

the imaging device comprises a camera configured to capture images in the IR.

23. The HMD of claim 21, wherein the first surface of the back optical element comprises a Fresnel surface.