Flexure based guidance system for varifocal head-mounted displays

Patent metadata

Field	Value
Publication number	US-10915162-B2
Application number	US-201816149303-A
Country	US
Kind code	B2
Filing date	Oct 2, 2018
Priority date	Jun 15, 2018
Publication date	Feb 9, 2021
Grant date	Feb 9, 2021

Abstract

A varifocal head mounted display (HMD) includes an electronic display, an optical system, and the guidance system. The electronic display presents content. The optical system includes one or more optical elements and provides the content to an eyebox of the HMD. The guidance system is a flexure based guidance system that includes an actuator and a first and second flexure elements (e.g., parallel beam, dual Roberts, etc.) guiding movement of the electronic display along an optical axis of the optical system in order to adjust a location of one or moveable elements in the optical system and, thereby, control a location of an image plane. The first and second flexure elements are able to flex or bend with movement of the actuator to adjust the location of the one or moveable elements that includes the electronic display and/or one or more optical elements of the optical system.

First claim

What is claimed is:

1. A headset comprising:
an electronic display;
an optics block;
a varifocal actuation system comprising:
an actuator positioned off-axis relative to an optical axis of the optics block configured to adjust a location of an image plane of the headset by varying a distance between the electronic display and the optics block, the actuator having a movable end fixed relative to the electronic display and a fixed end fixed relative to the optics block; and
a guidance system comprising:
a first flexure element guiding movement of the electronic display along the optical axis in a first dimension, the first flexure element comprising a first pair of flexure beams parallel to each other; and
a second flexure element guiding movement of the electronic display along the optical axis in a second dimension, the second flexure element comprising a second pair of flexure beams parallel to each other, a first end of each of the first flexure element and the second flexure element being fixed to the movable end of the actuator and a second end being fixed relative to the optics block, the first pair of flexure beams and the second pair of flexure beams arched in shape to conform to a shape around the optics block within the headset.

2. The headset of claim 1 , wherein the first flexure element and the second flexure element are compound parallel beam flexures that each include an additional pair of flexure beams, the additional pair of flexure beams in the first flexure element parallel to the first pair of flexure beams and the additional pair of flexure beams in the second flexure element parallel to the the second pair of flexure beams.

3. The headset of claim 1 , wherein the first flexure element is configured to minimize tilt of the electronic display in the first dimension and the second flexure element guide is configured to minimize tilt in the second dimension.

4. The headset of claim 1 , wherein the varifocal actuation system varies a distance between the electronic display and the optics block along a z-axis, the first dimension corresponds to an x-axis, and the second dimension corresponds to an y-axis, wherein the first flexure element guides movement of the electronic display along the z-axis while minimizing tilt about the x-axis and the second flexure element guides movement of the electronic display along the z-axis while minimizing tilt about the y-axis.

5. The headset of claim 1 , wherein the actuator is a voice coil actuator, stepper motor, or a brushless DC electric motor.

6. The headset of claim 1 , wherein the headset is a head mounted display (HMD) or a near eye display (NED).

7. The headset of claim 1 , further comprising:
an encoder in communication with the varifocal actuation system configured to:
receive an input corresponding to a focal length for a frame of a virtual scene being presented on the electronic display;
determine a position for the electronic display relative to the optics block to achieve the focal length; and
provide the actuator with an instruction causing the electronic display to move relative to the optics block to achieve the focal length for the frame of the virtual scene.

8. A varifocal actuation system of a headset comprising:
an actuator configured to adjust an image plane at an exit pupil of the headset by varying a distance between an electronic display and an optics block of the headset, the actuator having a movable end fixed relative to the electronic display and a fixed end fixed relative to the optics block; and
a guidance system comprising:
a first flexure element guiding movement of the electronic display in a first dimension, the first flexure element comprising a first pair of flexure beams parallel to each other; and
a second flexure element guiding movement of the electronic display in a second dimension, the second flexure element comprising a second pair of flexure beams parallel to each other, a first end of each of the first flexure element and the second flexure element being fixed to the movable end of the actuator and a second end being fixed relative to the optics block, the first pair of flexure beams and the second pair of flexure beams arched in shape to conform to a shape around the optics block within the headset.

9. The varifocal actuation system of claim 8 , wherein the actuator is positioned off-axis relative to an optical axis of the optics block.

10. The varifocal actuation system of claim 8 , wherein the first flexure element and the second flexure element are compound parallel beam flexures that each include an additional pair of flexure beams, the additional pair of flexure beams in the first flexure element parallel to the first pair of flexure beams and the additional pair of flexure beams in the second flexure element parallel to the second pair of flexure beams.

11. The varifocal actuation system of claim 8 , wherein the first flexure element is configured to minimize tilt of the electronic display in the first dimension and the second flexure element guide is configured to minimize tilt in the second dimension.

12. The varifocal actuation system of claim 8 , wherein the actuator is a voice coil actuator, stepper motor, or a brushless DC electric motor, and wherein the varifocal actuation system is part of a head mounted display (HMD) or a near eye display (NED).

13. The varifocal actuation system of claim 8 , wherein the varifocal actuation system varies the distance between the electronic display and the optics block along a z-axis, the first dimension corresponds to an x-axis, and the second dimension corresponds to an y-axis, wherein the first flexure element guides movement of the electronic display along the z-axis while minimizing tilt about the x-axis and the second flexure element guides movement of the electronic display along the z-axis while minimizing tilt about the y-axis.

Assignees

• Facebook Tech Llc

Inventors

• Ebert Ryan Michael
• Lindberg David C
• Moczydlowski Seth Robert
• Smith Clinton

Classifications

• G02B27/0176 Primary

  characterised by mechanical features · CPC title

• G02B7/005

  Motorised alignment · CPC title

• G06F3/011 Primary

  Arrangements for interaction with the human body, e.g. for user immersion in virtual reality (blind teaching G09B21/00) · CPC title

• G02B2027/0185

  Displaying image at variable distance · CPC title