WO2019232282A1

WO2019232282A1 - Compact variable focus configurations

Info

Publication number: WO2019232282A1
Application number: PCT/US2019/034763
Authority: WO
Inventors: Bach Nguyen; David Lundmark
Original assignee: Magic Leap, Inc.
Priority date: 2018-05-30
Filing date: 2019-05-30
Publication date: 2019-12-05
Also published as: CN112236713B; CN112236713A; EP3803488A1; JP2024024075A; JP2021525902A; EP3803488A4; US11204491B2; US20190369383A1

Abstract

One embodiment is directed to a head-wearable viewing component for presenting virtual image information to a user, comprising: a head wearable frame; a left optical element for a left eye of the user, the left optical element coupled to the head wearable frame and comprising a left fluid/membrane lens configured to have an electromechanically adjustable focal length for the left eye of the user; a right optical element for a right eye of the user, the right optical element coupled to the head wearable frame and comprising a right fluid/membrane lens configured to have an electromechanically adjustable focal length for the right eye of the user; and a controller operatively coupled to the left optical element and right optical element and configured to provide one or more.

Description

COMPACT VARIABLE FOCUS CONFIGURATIONS

RELATED APPLICATION DATA:

The present application claims the benefit under 35 U.S.C. § 119 to U.S. Provisional Applications Serial No. 62/678,234 filed May 30, 2018. The foregoing application is hereby incorporated by reference into the present application in its entirety.

FIELD OF THE INVENTION:

This invention is related to viewing optics assemblies, and more specifically to compact variable focus configurations.

BACKGROUND :

It is desirable that mixed reality, or augmented reality, near-eye displays be lightweight, low-cost, have a small form- factor, have a wide virtual image field of view, and be as transparent as possible. In addition, it is desirable to have configurations that present virtual image information in

multiple focal planes (for example, two or more) in order to be practical for a wide variety of use-cases without exceeding an acceptable allowance for vergence-accommodation mismatch.

Referring to Figure 1, an augmented reality system is

illustrated featuring a head-worn viewing component (2), a hand held controller component (4), and an interconnected auxiliary computing or controller component (6) which may be configured to be worn as a belt pack or the like on the user. Each of these components may be operatively coupled (10, 12, 14, 16, 17, 18) to each other and to other connected resources (8) such as cloud computing or cloud storage resources via wired or wireless communication configurations, such as those specified by IEEE 802.11, Bluetooth (RTM) , and other connectivity standards and configurations. As described, for example, in U.S. Patent

Application Serial Numbers 14/555,585, 14/690,401, 14/331,218, 15/481,255, and 62/518,539, each of which is incorporated by reference herein in its entirety, various aspects of such components are described, such as various embodiments of the two depicted optical elements (20) through which the user may see the world around them along with visual components which may be produced by the associated system components, for an augmented reality experience. In some variations, true variable focus components may be utilized as components of the optical elements (20) to provide not only one or two focal planes, but a spectrum thereof, selectable or tunable by an integrated control system. Referring to Figures 2A-2C and Figure 3, one category of variable focus configurations comprises a fluid type of lens coupled to a membrane and adjustably housed such that upon rotation of a motor (24), an associated mechanical drive

assembly (26) rotationally drives a cam member (28) against a lever assembly (30), which causes two opposing perimetric plates (38, 40) to rotate (48, 46) relative to a main housing assembly (41), and rotate about associated rotation pin joints (32, 34) such that the fluid/membrane lens (36) is squeezed (44/42; or released, depending upon the motor 24 / cam 28

direction/positioning), as shown in Figure 3. This

squeezing/releasing and reorientation of the opposing perimetric plates (38, 40) relative to each other changes the focus of the fluid/membrane lens (36), thus providing an electromechanically adjustable variable focus assembly. One of the challenges with such a configuration is that it is relatively bulky from a geometric perspective for integration into a head-wearable type of system component (2) . Another challenge is that with such a configuration, due to the nature of the system that re-orients the opposing perimetric plates (38, 40) relative to each other as each of them pivots at the bottom relative to the frame that couples the assembly, there is a concomitant change in image position as the focus is varied; this brings in another

undesirably complicating variable which must be dealt with in calibration or other steps or configurations. There is a need for compact variable focus lens systems and assemblies which are optimized for use in wearable computing systems.

Summary of the Invention:

One embodiment is directed to a head-wearable viewing component for presenting virtual image information to a user, comprising: a head wearable frame; a left optical element for a left eye of the user, the left optical element coupled to the head wearable frame and comprising a left fluid/membrane lens configured to have an electromechanically adjustable focal length for the left eye of the user; a right optical element for a right eye of the user, the right optical element coupled to the head wearable frame and comprising a right fluid/membrane lens configured to have an electromechanically adjustable focal length for the right eye of the user; and a controller

operatively coupled to the left optical element and right optical element and configured to provide one or more commands thereto to modify the focal lengths of the left optical element and right optical element. The head-wearable viewing component of claim 1, wherein at least one of the left and right optical elements comprises an actuation motor intercoupled between two frame members. The actuation motor may be configured to provide linear actuation. The actuation motor may be configured to provide rotational actuation. The two frame members may be coupled to the left fluid/membrane lens and configured to change the focal length for the user by moving relative to each other. The two frame members may be rotatable relative to each other to modify the focal length for the user. The two frame members may be displaceable relative to each other in a non-rotational manner. The actuation motor may comprise a stepper motor. The actuation motor may comprise a servo motor. The actuation motor may comprise a piezoelectric actuator. The actuation motor may comprise an ultrasonic motor. The actuation motor may comprise an electromagnetic actuator. The actuation motor may comprise a shape memory metal alloy actuator. The controller may be configured to command the left and right optical elements to adjust to one of two selectable predetermined focal lengths. The controller may be configured to command the left and right optical elements to adjust to one of three or more selectable predetermined focal lengths.

BRIEF DESCRIPTION OF THE DRAWINGS:

Figure 1 illustrates a system configuration featuring a head wearable component with left and right optical elements in accordance with the present invention. Figures 2A-2c and Figure 3 illustrate various aspects of a fluid lens system.

Figures 4A-4B illustrate various aspects of a single-motor compact fluid lens configuration in accordance with the present invention . Figures 5, 6, and 7A-7B illustrate various aspects of multi-motor compact fluid lens configurations in accordance with the present invention.

Figures 8A and 8B illustrate various aspects of system configurations featuring a head wearable component with left and right optical elements in accordance with the present invention.

DETAILED DESCRIPTION:

Referring to Figure 4A, two main elements of one inventive variable focus assembly (50) are a fluid/membrane lens (36) interposed between two relatively rigid perimetric frame members (70, 72) . In the depicted embodiment, between the

fluid/membrane lens (36) and each of the rigid perimetric frame members (70, 72) is a rotatable adjustment perimetric member (52, 54) which may be controllably and rotatably adjusted relative to the rigid perimetric frame members (70, 72) using a compact actuation motor (64), such as a stepper motor, servo motor, ultrasonic motor (i.e., such as those comprising a plurality of piezoelectric material components comprising one or more piezoelectric materials, such as lead zirconate titanate, lithium niobate, or other single crystal materials, configured in a substantially circular arrangement and operatively coupled to a stator and rotor to produce rotary ultrasonic motor

activation, or operatively coupled to a stator and slider to produce linear translation ultrasonic motor activation) , or other electromechanical actuator, which may be coupled to the rigid perimetric frame members (56, 58) and also coupled to the rotatable adjustment perimetric members (52, 54) using a

coupling assembly such as that depicted in Figure 4B, featuring a shaft (62) coupled to a barrel member (60) which is coupled to a pin (61) that interfaces with the rotatable adjustment

perimetric members (52, 54) as shown. In one embodiment, the motor (64) may be configured to produce controlled linear motion of the shaft (62) and intercoupled barrel member (60) relative to the depicted cylindrical housing (63) of the motor (64), such that by virtue of the intercoupled pin (61), the rotatable adjustment perimetric members (52, 54) are rotated relative to the rigid perimetric frame members (70, 72) about an axis substantially parallel with a central axis (65) that is perpendicular to the center of the intercoupled fluid/membrane lens (36) . In another embodiment, the motor (64) may be

configured to produce rotational motion of the shaft (62) relative to the depicted cylindrical housing (63) of the motor (64), and the mechanical coupling between the shaft (62) and barrel member (60) may comprise a threaded interface, such that by virtue of the intercoupled pin (61), the rotatable adjustment perimetric members (52, 54) are rotated relative to the rigid perimetric frame members (70, 72) about an axis substantially parallel with a central axis (65) that is perpendicular to the center of the intercoupled fluid/membrane lens (36) . The

mechanical interface between the rotatable adjustment perimetric members (52, 54) and the rigid perimetric frame members (70, 72) may be configured to comprise perimetrically located features, such as ramps, bumps, or step-ups, which will cause the

intercoupled fluid/membrane lens (36) to be squeezed or loosened with a substantially even perimetric loading, such as by three or more interfacial feature groupings (i.e., one at every 120 degrees around the 360 degree perimetric interfaces between the rotatable adjustment perimetric members (52, 54) and the rigid perimetric frame members (70, 72) . In other words, the

fluid/membrane lens (36) may be loosened or tightened relatively evenly, preferably without substantial movement or reorientation of the image position relative to the plane of the lens.

Further, the mechanical perimetric interfaces may be configured such that sequenced levels of tightening or loosening of

fluid/membrane lens (36) may be predictably obtained. For example, in one embodiment the motor may be operatively coupled to a controller, such as a microcontroller or microprocessor, such that a desired or commanded tightening or loosening of the fluid/membrane lens (36), which may be correlated with a predetermined focal length for the fluid/membrane lens (36), may be reliably obtained, preferably with relatively low latency, via commands to the motor from the controller. One advantage of such a configuration as shown and described in reference to Figures 4A and 4B is that a single motor may be utilized to control the focal length of the fluid/membrane lens (36) .

Referring to Figures 5-7B, other embodiments are

illustrated which are configured to provide substantially even perimetric loading (and thus focus adjustment without

substantial movement or reorientation of image position) for a compact variable focus configuration featuring an intercoupled fluid/membrane lens (36) .

Referring to Figure 5, a compact variable focus assembly (68) features two rigid perimetric frame members (70, 72) and an intercoupled fluid/membrane lens (36), with substantially even perimetric loading of the fluid/membrane lens (36) provided by a plurality of electromagnetic actuators (76, 77, 78), which may be utilized to controllably urge or repel the two rigid

perimetric frame members (70, 72) relative to each other to provide controllable focal adjustment. The electromagnetic actuators (76, 77, 78) preferably are placed equidistantly from each other perimetrically (i.e., about 120 degrees from each other) to provide even loading with a 3-actuator configuration as shown. Other embodiments may include more actuators, such as four actuators at 90 degrees apart, etc. In one embodiment, each of the electromagnetic actuators (76, 77, 78) may be operatively coupled between the perimetric frame members (70, 72) such that upon actuation, they urge or repel the perimetric frame members (70, 72) relative to each other with linear actuation; in another embodiment each of the electromagnetic actuators (76,

77, 78) may be operatively coupled between the perimetric frame members (70, 72) such that upon actuation, they cause rotational motion of an intercoupling member, such as an intercoupling member similar to the shaft member (62) of the assembly of Figure 4B, which may be interfaced with a threaded member, such as a threaded member similar to the barrel member (60) of the assembly of Figure 4B which may be coupled to one of the

perimetric frame members (70, 72), for example, to be converted to linear motion to urge or repel the perimetric frame members (70, 72) relative to each other. In other words, the

electromagnetic actuators (76, 77, 78) may be configured to produce either linear or rotational actuation motion, and this linear or rotational actuation motion may be utilized to urge or repel the two rigid perimetric frame members (70, 72) relative to each other to provide controllable focal adjustment.

Preferably one or more predictable levels of tightening or loosening of fluid/membrane lens (36) may be obtained through operation of the electromagnetic actuators (76, 77, 78) . For example, in one embodiment the electromagnetic actuators (76,

77, 78) may be operatively coupled to a controller, such as a microcontroller or microprocessor, such that a desired or commanded tightening or loosening of the fluid/membrane lens (36), which may be correlated with a predetermined focal length for the fluid/membrane lens (36), may be reliably obtained, preferably with relatively low latency, via commands to the electromagnetic actuators (76, 77, 78) from the controller.

Referring to Figure 6, a compact variable focus assembly (74) features two rigid perimetric frame members (70, 72) and an intercoupled fluid/membrane lens (36), with substantially even perimetric loading of the fluid/membrane lens (36) provided by a plurality of shape memory metal alloy actuators (80, 82, 84), which may be utilized to controllably urge or repel the two rigid perimetric frame members (70, 72) relative to each other to provide controllable focal adjustment. The shape memory metal alloy actuators (80, 82, 84) preferably are placed equidistantly from each other perimetrically (i.e., about 120 degrees from each other) to provide even loading with a 3- actuator configuration as shown. Other embodiments may include more actuators, such as four actuators at 90 degrees apart, etc. In one embodiment, each of the shape memory metal alloy

actuators (80, 82, 84) may be operatively coupled between the perimetric frame members (70, 72) such that upon actuation, they urge or repel the perimetric frame members (70, 72) relative to each other with linear actuation; in another embodiment each of the shape memory metal alloy actuators (80, 82, 84) may be operatively coupled between the perimetric frame members (70,

72) such that upon actuation, they cause rotational motion of an intercoupling member, such as an intercoupling member similar to the shaft member (62) of the assembly of Figure 4B, which may be interfaced with a threaded member, such as a threaded member similar to the barrel member (60) of the assembly of Figure 4B which may be coupled to one of the perimetric frame members (70, 72), for example, to be converted to linear motion to urge or repel the perimetric frame members (70, 72) relative to each other. In other words, the shape memory metal alloy actuators (80, 82, 84) may be configured to produce either linear or rotational actuation motion, and this linear or rotational actuation motion may be utilized to urge or repel the two rigid perimetric frame members (70, 72) relative to each other to provide controllable focal adjustment.

Preferably one or more predictable levels of tightening or loosening of fluid/membrane lens (36) may be obtained through operation of the shape memory metal alloy actuators (80, 82,

84) . For example, in one embodiment the shape memory metal alloy actuators (80, 82, 84) may be operatively coupled to a controller, such as a microcontroller or microprocessor, such that a desired or commanded tightening or loosening of the fluid/membrane lens (36), which may be correlated with a

predetermined focal length for the fluid/membrane lens (36), may be reliably obtained, preferably with relatively low latency, via commands to the shape memory metal alloy actuators (80, 82, 84) from the controller.

Referring to Figures 7A and 7B, a compact variable focus assembly (76) features two rigid perimetric frame members (70,

72) and an intercoupled fluid/membrane lens (36), with

substantially even perimetric loading of the fluid/membrane lens (36) provided by a plurality of piezoelectric actuators (86, 88, 90), which may be utilized to controllably urge or repel the two rigid perimetric frame members (70, 72) relative to each other to provide controllable focal adjustment. Each of the

piezoelectric actuators (80, 82, 84), may comprise one or more piezoelectric cells configured to produce a given load and displacement change upon actuation, or may comprise a socalled "ultrasound" or "ultrasonic" actuator configuration (i.e., such as those comprising a plurality of piezoelectric material components comprising one or more piezoelectric materials, such as lead zirconate titanate, lithium niobate, or other single crystal materials, configured in a substantially circular arrangement and operatively coupled to a stator and rotor to produce rotary ultrasonic motor activation, or operatively coupled to a stator and slider to produce linear translation ultrasonic motor activation) . The piezoelectric actuators (80, 82, 84) preferably are placed equidistantly from each other perimetrically (i.e., about 120 degrees from each other) to provide even loading with a 3-actuator configuration as shown. Other embodiments may include more actuators, such as four actuators at 90 degrees apart, etc. In one embodiment, each of the piezoelectric actuators (80, 82, 84) may be operatively coupled between the perimetric frame members (70, 72) such that upon actuation, they urge or repel the perimetric frame members (70, 72) relative to each other with linear actuation; in another embodiment each of the piezoelectric actuators (80, 82, 84) may be operatively coupled between the perimetric frame members (70, 72) such that upon actuation, they cause rotational motion of an intercoupling member, such as an intercoupling member similar to the shaft member (62) of the assembly of Figure 4B, which may be interfaced with a threaded member, such as a threaded member similar to the barrel member (60) of the assembly of Figure 4B which may be coupled to one of the

piezoelectric actuators (80, 82, 84) may be configured to produce either linear or rotational actuation motion, and this linear or rotational actuation motion may be utilized to urge or repel the two rigid perimetric frame members (70, 72) relative to each other to provide controllable focal adjustment.

Preferably one or more predictable levels of tightening or loosening of fluid/membrane lens (36) may be obtained through operation of the piezoelectric actuators (80, 82, 84) . For example, in one embodiment the piezoelectric actuators (80, 82, 84) may be operatively coupled to a controller, such as a microcontroller or microprocessor, such that a desired or commanded tightening or loosening of the fluid/membrane lens (36), which may be correlated with a predetermined focal length for the fluid/membrane lens (36), may be reliably obtained, preferably with relatively low latency, via commands to the piezoelectric actuators (80, 82, 84) from the controller. Referring to Figure 7B, depending upon how much mechanical throw is needed in each of the piezoelectric actuators for a given variable focus lens configuration, each of the

piezoelectric actuators may comprise an assembly of a series of individual piezoelectric devices (92, 94, etc) intercoupled such that activation of each provides a given mechanical throw which is added to others in the assembly to produce an overall

assembly throw which is suitable for the application.

Referring to Figure 8A, an assembly configuration is illustrated featuring componentry such as discussed above in reference to Figures 4A and 4B, with a head wearable component (2) comprising a frame (130) mountable on a user's head so that the user's left (100) and right (102) eyes are exposed to the optical elements (20; here a left optical element 110 and right optical element 112 are separately labelled; these optical elements feature left and right fluid/membrane lenses, 36, and 37, respectively) . Left (114) and right (116) motors are configured to electromechanically adjust the focal length of each optical element, as described above in reference to Figures 4A and 4B, for example. A controller (108), such as a micro controller or microprocessor, may be utilized to issue commands to the motors (114, 116) to adjust the focal lengths. In various embodiments, cameras (104, 106) may be coupled to the frame (130) and configured to capture data pertaining to the positions of each of the eyes (100, 102); this information may be utilized by the controller (108) in determining how to command the motors (114, 116) in terms of desired focal length. For example, if it is determined that the user is focused on a close-in object relative to the wearable component (2), the system may be configured to have the controller utilize the motors to switch to a closer focal length. Figure 8B

illustrates a configuration analogous to that of Figure 8A, but with an electromechanical actuation configuration akin to those described in reference to Figures 5-7B, wherein a plurality of motors or actuators (118, 120, 122; 124, 126, 128) may be operatively coupled to a controller (108) and utilized to adjust focal length of the optical elements (110, 112) .

Various example embodiments of the invention are described herein. Reference is made to these examples in a non-limiting sense. They are provided to illustrate more broadly applicable aspects of the invention. Various changes may be made to the invention described and equivalents may be substituted without departing from the true spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation, material, composition of matter, process, process act(s) or step(s) to the obj ective ( s ) , spirit or scope of the present invention. Further, as will be appreciated by those with skill in the art that each of the individual variations

described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present inventions.

All such modifications are intended to be within the scope of claims associated with this disclosure.

The invention includes methods that may be performed using the subject devices. The methods may comprise the act of

providing such a suitable device. Such provision may be

performed by the end user. In other words, the "providing" act merely requires the end user obtain, access, approach, position, set-up, activate, power-up or otherwise act to provide the requisite device in the subject method. Methods recited herein may be carried out in any order of the recited events which is logically possible, as well as in the recited order of events. Example aspects of the invention, together with details regarding material selection and manufacture have been set forth above. As for other details of the present invention, these may be appreciated in connection with the above-referenced patents and publications as well as generally known or appreciated by those with skill in the art. The same may hold true with respect to method-based aspects of the invention in terms of additional acts as commonly or logically employed.

In addition, though the invention has been described in reference to several examples optionally incorporating various features, the invention is not to be limited to that which is described or indicated as contemplated with respect to each variation of the invention. Various changes may be made to the invention described and equivalents (whether recited herein or not included for the sake of some brevity) may be substituted without departing from the true spirit and scope of the

invention. In addition, where a range of values is provided, it is understood that every intervening value, between the upper and lower limit of that range and any other stated or

intervening value in that stated range, is encompassed within the invention.

Also, it is contemplated that any optional feature of the inventive variations described may be set forth and claimed independently, or in combination with any one or more of the features described herein. Reference to a singular item, includes the possibility that there are plural of the same items present. More specifically, as used herein and in claims

associated hereto, the singular forms "a, " "an, " "said, " and "the" include plural referents unless the specifically stated otherwise. In other words, use of the articles allow for "at least one" of the subject item in the description above as well as claims associated with this disclosure. It is further noted that such claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as "solely, " "only" and the like in connection with the recitation of claim elements, or use of a "negative" limitation.

Without the use of such exclusive terminology, the term "comprising" in claims associated with this disclosure shall allow for the inclusion of any additional element--irrespective of whether a given number of elements are enumerated in such claims, or the addition of a feature could be regarded as transforming the nature of an element set forth in such claims. Except as specifically defined herein, all technical and

scientific terms used herein are to be given as broad a commonly understood meaning as possible while maintaining claim validity.

The breadth of the present invention is not to be limited to the examples provided and/or the subject specification, but rather only by the scope of claim language associated with this disclosure .

Claims

CLAIMS What is claimed:

1. A head-wearable viewing component for presenting virtual image information to a user, comprising:

a. a head wearable frame;

b. a left optical element for a left eye of the user, the left optical element coupled to the head wearable frame and comprising a left fluid/membrane lens configured to have an electromechanically adjustable focal length for the left eye of the user;

c. a right optical element for a right eye of the user, the right optical element coupled to the head wearable frame and comprising a right fluid/membrane lens configured to have an electromechanically adjustable focal length for the right eye of the user; and d. a controller operatively coupled to the left optical element and right optical element and configured to provide one or more commands thereto to modify the focal lengths of the left optical element and right optical element.

2. The head-wearable viewing component of claim 1, wherein at least one of the left and right optical elements comprises an actuation motor intercoupled between two frame members.

3. The head-wearable viewing component of claim 2, wherein the actuation motor is configured to provide linear actuation.

4. The head-wearable viewing component of claim 2, wherein the actuation motor is configured to provide rotational actuation .

5. The head-wearable viewing component of claim 2, wherein the two frame members are coupled to the left fluid/membrane lens and configured to change the focal length for the user by moving relative to each other.

6. The head-wearable viewing component of claim 2, wherein the two frame members are rotatable relative to each other to modify the focal length for the user.

7. The head-wearable viewing component of claim 2, wherein the two frame members are displaceable relative to each other in a non-rotational manner.

8. The head-wearable viewing component of claim 2, wherein the actuation motor comprises a stepper motor.

9. The head-wearable viewing component of claim 2, wherein the actuation motor comprises a servo motor.

10. The head-wearable viewing component of claim 2, wherein the actuation motor comprises a piezoelectric actuator.

11. The head-wearable viewing component of claim 2, wherein the actuation motor comprises an ultrasonic motor.

12. The head-wearable viewing component of claim 2, wherein the actuation motor comprises an electromagnetic actuator.

13. The head-wearable viewing component of claim 2, wherein the actuation motor comprises a shape memory metal alloy actuator .

14. The head-wearable viewing component of claim 2, wherein the controller is configured to command the left and right optical elements to adjust to one of two selectable

predetermined focal lengths.

15. The head-wearable viewing component of claim 2, wherein the controller is configured to command the left and right optical elements to adjust to one of three or more

selectable predetermined focal lengths.