Systems, devices, and methods for eyebox expansion displays in wearable heads-up displays

• US 10,191,283 B2
• Filed: 02/17/2016
• Issued: 01/29/2019
• Est. Priority Date: 02/17/2015
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: North Inc.
• Inventors: Alexander, Stefan, Bailey, Matthew, Morrison, Vance R., Holland, Lloyd Frederick
• Primary Examiner(s): Chang, Audrey Y
• Application Number:
  US15/046,269
• Publication Number:
  US 20160238845A1
• Time in Patent Office: 1,077 Days
• Field of Search: 359 13, 359 15, 359630, 345 8, 345 7, 353 7
• CPC Class Codes: G02B 2027/0112 comprising device for genereting colour display
• CPC Class Codes: G02B 2027/0123 comprising devices increasing the field of view
• CPC Class Codes: G02B 2027/0125 Field-of-view increase by wavefront division
• CPC Class Codes: G02B 2027/0174 holographic
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 26/10 Scanning systems
• CPC Class Codes: G02B 27/0081 with means for altering, e.g. enlarging, the entrance or exit pupil
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 27/12 operating by refraction only
• CPC Class Codes: G03H 1/2645 Multiplexing processes, e.g. aperture, shift, or wavefront multiplexing
• CPC Class Codes: G03H 1/265 Angle multiplexing; Multichannel holograms G03H1/268 takes precedence
• CPC Class Codes: G03H 2001/266 Wavelength multiplexing
• 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
• CPC Class Codes: G09G 3/001 using specific devices not provided for in groups G09G3/02 - G09G3/36, e.g. using an intermediate record carrier such as a film slide; Projection systems; Display of non-alphanumerical information, solely or in combination with alphanumerical information, e.g. digital display on projected diapositive as background slide projectors per se G03B23/00 = 42 HP

Abstract

Systems, devices, and methods for eyebox expansion by exit pupil replication in wearable heads-up displays (“WHUDs”) are described. A WHUD includes a scanning laser projector (“SLP”), a holographic combiner, and an exit pupil selector positioned in the optical path therebetween. The exit pupil selector is controllably switchable into and between N different configurations. In each of the N configurations, the exit pupil selector receives a light signal from the SLP and redirects the light signal towards the holographic combiner effectively from a respective one of N virtual positions for the SLP. The holographic combiner converges the light signal to a particular one of N exit pupils at the eye of the user based on the particular virtual position from which the light signal is made to effectively originate. In this way, multiple instances of the exit pupil are distributed over the eye and the eyebox of the WHUD is expanded.

Claims

1. A wearable heads-up display comprising:

a support structure that in use is worn on a head of a user;

a holographic combiner carried by the support structure, wherein the holographic combiner is positioned within a field of view of an eye of the user when the support structure is worn on the head of the user;

a scanning laser projector carried by the support structure, the scanning laser projector comprising a laser module to produce light signals and at least one scan mirror to reflect the light signals to select regions of the holographic combiner;

an exit pupil selector carried by the support structure and positioned in an optical path between the at least one scan mirror and the holographic combiner, the exit pupil selector controllably switchable into and between respective ones of N different discrete orientations, where N is an integer greater than 1, wherein in each one of the N different discrete orientations the exit pupil selector is positioned and oriented to receive at least one light signal generated by the scanning laser projector and redirect the at least one light signal towards the holographic combiner effectively from a respective one of N discrete spatially-separated virtual positions for the scanning laser projector, and wherein the holographic combiner comprises at least one hologram positioned and oriented to, for each one of the N different discrete orientations of the exit pupil selector, converge light signals received from the exit pupil selector to a respective one of N discrete exit pupils at or proximate the eye of the user; and

an eye tracker carried by the support structure and communicatively coupled to the exit pupil selector, the eye tracker positioned and oriented to determine a gaze direction of the eye of the user, wherein the exit pupil selector is controllably switchable into and between respective ones of the N different discrete orientations based on the gaze direction of the eye of the user determined by the eye tracker.

2. The wearable heads-up display of claim 1 wherein the exit pupil selector is controllably switchable into and between respective ones of the N different discrete orientations by at least one form of movement selected from a group consisting of:

a translation of at least one optical element of the exit pupil selector, a rotation of at least one optical element of the exit pupil selector, and a displacement of at least one optical element of the exit pupil selector.

3. The wearable heads-up display of claim 1 wherein the exit pupil selector comprises at least one dynamic optical element selected from a group consisting of:

at least one microelectromechanical systems (“

MEMS”

) based optical element and at least one piezo-based optical element.

4. The wearable heads-up display of claim 1 wherein the support structure has a shape of an eyeglasses frame.

5. The wearable heads-up display of claim 4, further comprising:

a prescription eyeglass lens, wherein the holographic combiner is carried by the prescription eyeglass lens.

6. The wearable heads-up display of claim 1 wherein the holographic combiner includes at least N multiplexed holograms, and wherein for each one of the N different discrete orientations of the exit pupil selector, a respective one of the at least N multiplexed holograms converges light signals received from the exit pupil selector to a respective one of the N discrete exit pupils at or proximate the eye of the user.

7. The wearable heads-up display of claim 1 wherein:

the scanning laser projector includes a red laser diode, a green laser diode, and a blue laser diode; and

the holographic combiner includes a wavelength-multiplexed holographic combiner that includes at least one red hologram, at least one green hologram, and at least one blue hologram, and wherein for each one of the N different discrete orientations of the exit pupil selector;

the at least one red hologram converges a red component of light signals received from the exit pupil selector to a respective one of the N discrete exit pupils at or proximate the eye of the user, the at least one green hologram converges a green component of light signals received from the exit pupil selector to a respective one of the N discrete exit pupils at or proximate the eye of the user, and the at least one blue hologram converges a blue component of light signals received from the exit pupil selector to a respective one of the N discrete exit pupils at or proximate the eye of the user.

8. The wearable heads-up display of claim 7 wherein the holographic combiner includes a wavelength-multiplexed and angle-multiplexed holographic combiner that includes at least N angle-multiplexed red holograms, at least N angle-multiplexed green holograms, and at least N angle-multiplexed blue holograms, and wherein for each one of the N different discrete orientations of the exit pupil selector:

a respective one of the at least N angle-multiplexed red holograms converges a red component of light signals received from the exit pupil selector to a respective one of the N discrete exit pupils at or proximate the eye of the user, a respective one of the at least N angle-multiplexed green holograms converges a green component of light signals received from the exit pupil selector to a respective one of the N discrete exit pupils at or proximate the eye of the user, and a respective one of the at least N angle-multiplexed blue holograms converges a blue component of light signals received from the exit pupil selector to a respective one of the N discrete exit pupils at or proximate the eye of the user.

9. The wearable heads-up display of claim 1 wherein the optical path between the scanning laser projector and the holographic combiner includes a total scan range θ

of the scanning laser projector, and wherein for each one of the N different discrete orientations of the exit pupil selector, the exit pupil selector is positioned and oriented to receive all light signals corresponding to a sweep of the total scan range θ

by the scanning laser projector and redirect all light signals corresponding to the sweep of the total scan range θ

of the scanning laser projector towards the holographic combiner effectively from a respective one of the N discrete spatially-separated virtual positions for the scanning laser projector.

10. The wearable heads-up display of claim 1 wherein the at least one light signal includes an image comprising at least two pixels.

11. The wearable heads-up display of claim 10 wherein in each one of the N different discrete orientations the exit pupil selector is positioned and oriented to receive the image generated by the scanning laser projector and redirect the image towards the holographic combiner effectively from a respective one of the N discrete spatially-separated virtual positions for the scanning laser projector, and wherein at least one hologram of the holographic combiner is positioned and oriented to redirect the image received from the exit pupil selector towards one of the N discrete exit pupils at or proximate the eye of the user.

12. The wearable heads-up display of claim 1, wherein the exit pupil selector comprises at least one dynamic optical element.

13. The wearable heads-up display of claim 12, wherein the at least one dynamic optical element includes at least one of MEMS-based lens, piezo-based lens, reflector, partial reflector, prism, diffractor, diffraction grating, and mirror.

14. A wearable heads-up display comprising:

a support structure that in use is worn on a head of a user;

a holographic combiner carried by the support structure, wherein the holographic combiner is positioned within a field of view of an eye of the user when the support structure is worn on the head of the user;

a scanning laser projector carried by the support structure, the scanning laser projector comprising a laser module to produce light signals and at least one scan mirror to reflect the light signals to select regions of the holographic combiner; and

an exit pupil selector carried by the support structure and positioned in an optical path between the at least one scan mirror and the holographic combiner, the exit pupil selector controllably switchable into and between respective ones of N different discrete orientations, where N is an integer greater than 1, wherein in each one of the N different discrete orientations the exit pupil selector is positioned and oriented to receive at least one light signal generated by the scanning laser projector and redirect the at least one light signal towards the holographic combiner along a respective optical path between the exit pupil selector and the holographic combiner, and wherein the holographic combiner comprises at least one hologram positioned and oriented to, for each one of the N different discrete orientations of the exit pupil selector, converge light signals received from the exit pupil selector to a respective one of N discrete exit pupils at or proximate the eye of the user; and

an eye tracker carried by the support structure and communicatively coupled to the exit pupil selector, the eye tracker positioned and oriented to determine a gaze direction of the eye of the user, wherein the exit pupil selector is controllably switchable into and between respective ones of the N different discrete orientations based on the gaze direction of the eye of the user determined by the eye tracker.

15. The wearable heads-up display of claim 14, wherein the exit pupil selector comprises at least one dynamic optical element.

16. A method of operating a wearable heads-up display, the wearable heads-up display including a scanning laser projector, a controllably switchable exit pupil selector, an eye tracker communicatively coupled to the exit pupil selector, and a holographic combiner positioned within a field of view of an eye of a user when the wearable heads-up display is worn on a head of the user, the method comprising:

determining a gaze direction of the eye of the user by the eye tracker;

controllably switching the exit pupil selector into a first discrete orientation based on the gaze direction of the eye of the user determined by the eye tracker;

generating a first light signal by a laser module of the scanning laser projector and reflecting the first light signal by at least one scan mirror of the scanning laser projector;

receiving the first light signal reflected by the at least one scan mirror by the exit pupil selector in the first discrete orientation;

redirecting the first light signal towards the holographic combiner effectively from a first discrete virtual position for the scanning laser projector by the exit pupil selector in the first discrete orientation;

redirecting the first light signal towards a first discrete exit pupil at the eye of the user by the holographic combiner;

determining the gaze direction of the eye of the user by the eye tracker;

controllably switching the exit pupil selector into a second discrete orientation based on the gaze direction of the eye of the user determined by the eye tracker;

generating a second light signal by the scanning laser projector;

receiving the second light signal by the exit pupil selector in the second discrete orientation;

redirecting the second light signal towards the holographic combiner effectively from a second discrete virtual position for the scanning laser projector by the exit pupil selector in the second discrete orientation, the second discrete virtual position spatially-separated from the first discrete virtual position; and

redirecting the second light signal towards a second discrete exit pupil at the eye of the user by the holographic combiner, the second discrete exit pupil spatially-separated from the discrete first exit pupil.