Variable focus assemblies
An example head-mounted display device includes a light projector, an optical assembly arranged to direct light from a light projector to a user, and an actuator module. The optical assembly includes a variable focus lens assembly including a rigid refractive component, a shaper ring defining an aperture, and a flexible lens membrane between the shaper ring and the rigid refractive component and covering the aperture. The refractive component, the shaper ring, and the lens membrane are arranged along an axis. The refractive component and the lens membrane define a chamber containing a volume of fluid. The actuator module is configured to adjust an optical power of the variable focus lens by moving the shaper ring relative to the refractive component along the axis, such that a curvature of the lens membrane in the aperture is modified.
1. A head-mounted display device comprising:
a light projector;
an optical assembly arranged to receive light from the light projector and direct the light to a user during use of the head-mounted display device, wherein the optical assembly comprises a variable focus liquid lens assembly comprising:
a rigid refractive component,
a shaper ring defining an aperture, and
a flexible lens membrane between the shaper ring and the rigid refractive component, the flexible lens membrane covering the aperture,
wherein the rigid refractive component, the shaper ring, and the flexible lens membrane are arranged along an axis,
wherein the rigid refractive component and the flexible lens membrane define a chamber between the flexible lens membrane and the refractive component, and
wherein a volume of fluid is disposed within the chamber; and
an actuator module coupled to the variable focus liquid lens assembly, wherein the actuator module is configured to adjust an optical power of the variable focus liquid lens by moving the shaper ring relative to the rigid refractive component along the axis, such that a curvature of the flexible lens membrane in the aperture is modified;
wherein the optical assembly comprises a second variable focus liquid lens assembly including:
a second rigid refractive component,
a second shaper ring defining a second aperture, and
a second flexible lens membrane between the second shaper ring and the second rigid refractive component, the second flexible lens membrane covering the second aperture,
wherein the second rigid refractive component, the second shaper ring, and the second flexible lens membrane are arranged along the axis,
wherein the second rigid refractive component and the second flexible lens membrane define a second chamber between the second flexible lens membrane and the second rigid refractive component,
wherein a second volume of fluid is disposed within the second chamber,
wherein the actuator module is configured to adjust an optical power of the second variable focus liquid lens assembly by moving the second shaper ring relative to the second rigid refractive component along the axis, such that a curvature of the second flexible lens membrane in the aperture is modified, and
wherein the optical assembly further comprises a support structure securing the variable focus liquid lens assembly to the second variable focus liquid lens assembly,
wherein the support structure comprises an element physically coupling the second rigid refractive component to the shaper ring, the element being composed of a material having a thermal expansion property such that, in a range of operating temperatures of the optical assembly, thermal expansion of the element is sufficient to reduce compression of the rigid refractive component against the shaper ring and to reduce compression of the second rigid refractive component against the second shaper ring to maintain an optical power of the variable focus liquid lens assembly and the second variable focus liquid lens assembly in the range of operating temperatures.
2. The head-mounted display of claim 1 , wherein the supporting structure comprises:
a first arm mounted to the shaper ring,
a second arm mounted to the second rigid refractive component, and
a bar extending from the first arm to the second arm.
3. The head-mounted display of claim 1 , wherein the actuator module is configured, during use of the head-mounted display device, to adjust the optical power of the variable focus liquid lens assembly and the optical power of the second variable focus liquid lens assembly, such that the optical power of the variable focus liquid lens assembly is the inverse of the optical power of the second variable focus liquid lens assembly.
4. The head-mounted display device of claim 3 , wherein the optical assembly further comprises an eyepiece disposed between the variable focus liquid lens assembly and the second variable focus liquid lens assembly,
wherein the eyepiece is configured to receive the light from the light projector and direct the light through one of the variable focus liquid lens assembly or the second variable focus liquid lens assembly to the user during use of the head-mounted display device.
5. The head-mounted display device of claim 3 , further comprising a control module configured to control the actuator module during use of the head-mounted display device, such that the optical power of the variable focus liquid lens assembly is the inverse of the optical power of the second variable focus liquid lens assembly.
6. The head-mounted display device of claim 1 , wherein the support structure is composed of the material.
7. The head-mounted display device of claim 1 , wherein in the range of operating temperatures of the optical assembly,
a position of the rigid refractive component relative to the shaper ring is maintained, and
a position of the second rigid refractive component relative to and the second shaper ring is maintained.
8. The head-mounted display device of claim 7 , wherein the support structure comprises:
a first portion extending from the second shaper ring to the rigid refractive component, and
a second portion extending from the second rigid refractive component to the shaper ring,
wherein the second portion comprises the material having the thermal expansion property, and
wherein the second portion is configured to, in the range of operating temperatures of the optical assembly:
maintain the position of the rigid refractive component relative to the shaper ring, and
maintain the position of the second rigid refractive component relative to and the second shaper ring.