# US 11,079,596 B2 · 3-dimensional electro-optical see-through displays

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- Number: US 11,079,596 B2
- Document ID: US11079596B2
- Status: Granted
- Kind: B2
- Application number: 14/729,195
- Filed: 2015-06-03
- Published: 2016-05-26
- Granted: 2021-08-03
- Earliest claimed: 2009-09-14
- Assignees: Arizona Board of Regents on Behalf of the University of Arizona
- Applicants: The Arizona Board of Regents On Behalf of the University of Arizona
- Inventors: Hong Hua; Sheng Liu
- Web page: https://patentgrep.com/patent/US11079596B2

## CPC

- G02B 27/0172: {characterised by optical features}
- G02B 26/004: {based on a displacement or a deformation of a fluid}
- G02B 27/017: {Head mounted}
- G02B 30/34: Stereoscopes providing a stereoscopic pair of separated images corresponding to parallactically displaced views of the same object, e.g. three-dimensional [3D] slide viewers
- G06T 19/006: {Mixed reality (object pose determination, tracking or camera calibration for mixed reality G06T7/00)}
- H04N 13/322: using varifocal lenses or mirrors
- H04N 13/344: with head-mounted left-right displays
- H04N 13/383: for tracking with gaze detection, i.e. detecting the lines of sight of the viewer's eyes
- G02B 2027/0127: {comprising devices increasing the depth of field}
- G02B 2027/0132: {comprising binocular systems}
- G02B 2027/0134: {of stereoscopic type}
- G02B 2027/014: {comprising information/image processing systems}
- G02B 2027/0145: {creating an intermediate image}
- G02B 2027/0147: {comprising a device modifying the resolution of the displayed image}
- G02B 2027/0187: {slaved to motion of at least a part of the body of the user, e.g. head, eye}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

An exemplary display is placed in an optical pathway extending from an entrance pupil of a person's eye to a real-world scene beyond the eye. The display includes at least one 2-D added-image source that is addressable to produce a light pattern corresponding to a virtual object. The source is situated to direct the light pattern toward the person's eye to superimpose the virtual object on an image of the real-world scene as perceived by the eye via the optical pathway. An active-optical element is situated between the eye and the added-image source at a location that is optically conjugate to the entrance pupil and at which the active-optical element forms an intermediate image of the light pattern from the added-image source. The active-optical element has variable optical power and is addressable to change its optical power to produce a corresponding change in perceived distance at which the intermediate image is formed, as an added image to the real-world scene, relative to the eye.

## Claims

### Claim 1

A method for displaying, to a person via a see-through display, an image of a virtual 3-D scene containing objects located at differing 3-D depths within the scene, comprising:
providing a 2-D display physically extending in two directions away from an optical axis of the see-through display;
providing an active-optical element at a location to receive a light pattern emitted by the 2-D display, the active-optical element having an addressable and variable optical power;
switching the optical power of the active-optical element to provide multiple respective focal planes at respective focal distances corresponding to the differing 3-D depths within the virtual 3-D scene, such that the focal distance of the light pattern produced by the 2-D display is modulated in a time-sequential manner;
creating a plurality of perspective views of the virtual 3-D scene, each perspective view containing respective virtual objects at distances associated with respective accommodation cues being provided by the 2-D display; and
synchronously with switching of the focal planes, updating the light pattern on the 2-D display to render a selected one of the plurality of perspective views matched to the respective accommodation cues being provided by the 2-D display, wherein a switching rate of the focal planes is sufficiently fast to avoid flicker.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the active-optical element is switched to change the optical power to produce a corresponding change in perceived distance at which an intermediate image is formed.

### Claim 3 (depends on 2)

The method according to claim 2, wherein the intermediate image is added to a real-world scene observable through the see-through display.

### Claim 4 (depends on 2)

The method according to claim 2, wherein a distance at which the intermediate image is formed can serve as an accommodation cue for the person with respect to the intermediate image.

### Claim 5 (depends on 2)

The method according to claim 2, wherein the step of switching the optical power includes correspondingly moving the intermediate image along an optical pathway relative to the focal plane to produce a corresponding change in distance of the image relative to the person's eye.

### Claim 6 (depends on 1)

The method according to claim 1, wherein, in synchrony with a signal driving the active-optical element, far and near virtual objects are rendered on two or more separate image frames and displayed sequentially.

### Claim 7 (depends on 1)

The method according to claim 1, wherein the switching rate, fN, is given by
f
N
=
f
min
N
,
where N is the total number of focal planes and fmin is a lowest response speed (in Hz) among the 2-D display, the active-optical element, and electronics driving the 2-D display and active-optical element.

### Claim 8 (depends on 1)

The method according to claim 1, wherein the 2-D display comprises a 2-D array of light-producing pixels.

### Claim 9 (depends on 1)

The method according to claim 1, wherein the step of switching the optical power includes controlling dioptric spacing between adjacent focal planes and an overall range of accommodation cues.

### Claim 10

A see-through display for placement in an optical pathway extending from an entrance pupil of a person's eye to a real-world scene beyond the eye for displaying to the person via the see-through display, an image of a virtual 3-D scene containing objects located at differing 3-D depths within the virtual 3-D scene, the display comprising:
a 2-D display physically extending in two directions away from an optical axis of the see-through display, the 2-D display addressable to produce at least two light patterns corresponding to respective virtual objects;
an active-optical element disposed at a location to receive the at least two light patterns emitted by the 2-D display, the active-optical element having an addressable and variable optical power;
a controller in communication with the 2-D display and the active-optical element, and configured to switch the optical power of the active-optical element to provide multiple respective focal planes at respective focal distances corresponding to the differing 3-D depths within the virtual 3-D scene, such that the focal distances of the at least two light patterns produced by the 2-D display is modulated in a time-sequential manner, the controller also configured to create a plurality of perspective views of the virtual 3-D scene, each perspective view containing respective virtual objects at distances associated with respective accommodation cues being provided by the 2-D display and configured to update the at least two patterns on the 2-D display, synchronously with switching of the focal planes, to render a selected one of the plurality of perspective views matched to the respective accommodation cues being provided by the 2-D display.

### Claim 11 (depends on 10)

The see-through display of claim 10, wherein the 2-D display comprises a 2-D array of light-producing pixels.

### Claim 12 (depends on 10)

The see-through display of claim 10, comprising a spherical mirror disposed on the optical axis in optical communication with the active-optical element and at a location such that the active-optical element is disposed between the spherical mirror and the 2-D display.

### Claim 13 (depends on 12)

The see-through display of claim 12, wherein the active-optical element is offset along the optical axis from the center of a radius of curvature of the spherical mirror.

### Claim 14 (depends on 13)

The see-through display of claim 13, wherein the active-optical element is offset by Δ, and an exit pupil of the 2-D display is magnified by an amount mp,
m
p
=
R
R
+
2
⁢
Δ
.

### Claim 15 (depends on 10)

The see-through display of claim 10, wherein the active-optical element comprises a refractive active-optical element.

### Claim 16 (depends on 15)

The see-through display of claim 15, wherein the refractive active-optical element comprises a liquid lens.