Electronic Device With A Tunable Lens

Abstract

A lens module in a head-mounted device may include a fluid-filled chamber, a semi-rigid lens element that at least partially defines the fluid-filled chamber, and at least one actuator configured to selectively bend the semi-rigid lens element. The semi-rigid lens element may become rigid along a first axis when the lens element is curved along a second axis perpendicular to the first axis. Six actuators that are evenly distributed around the periphery of the semi-rigid lens element may be used to control the curvature of the semi-rigid lens element. The semi-rigid lens element may initially be planar or non-planar. For example, the semi-rigid lens element may initially have a spherically convex surface and a spherically concave surface. A tunable spherical lens may be incorporated into the lens module to offset a parasitic spherical lens power from the semi-rigid lens element.

What is claimed is: 
     
         1 . A system, comprising:
 a head-mounted support structure;   a display that emits light;   a lens module supported by the head-mounted support structure that receives the light from the display, wherein the lens module comprises a flexible lens element with a periphery and a plurality of actuators around the periphery of the flexible lens element; and   control circuitry configured to control the plurality of actuators to dynamically adjust the flexible lens element.   
     
     
         2 . The system defined in  claim 1 , wherein each actuator is configured to pull radially outward on the periphery of the flexible lens element away from a center of the flexible lens element. 
     
     
         3 . The system defined in  claim 1 , wherein each actuator is a piezoelectric actuator. 
     
     
         4 . The system defined in  claim 1 , wherein each actuator is a linear electromagnetic actuator. 
     
     
         5 . The system defined in  claim 1 , wherein each actuator is configured to selectively press the periphery of the flexible lens element. 
     
     
         6 . The system defined in  claim 1 , further comprising:
 a gaze detection sensor configured to obtain gaze information, wherein the control circuitry is configured to control the actuators based on the gaze information.   
     
     
         7 . The system defined in  claim 1 , wherein the plurality of actuators comprises more than four actuators around the periphery of the flexible lens element and wherein the lens module further comprises a load-spreading ring that extends around the periphery of the flexible lens element. 
     
     
         8 . The system defined in  claim 1 , wherein the plurality of actuators comprises more than six actuators around the periphery of the flexible lens element. 
     
     
         9 . The system defined in  claim 1 , wherein the flexible lens element at least partially defines a fluid-filled chamber. 
     
     
         10 . The system defined in  claim 9 , wherein the control circuitry is configured to change an amount of fluid in the fluid-filled chamber. 
     
     
         11 . A system, comprising:
 a head-mounted support structure;   a display that emits light;   a lens module supported by the head-mounted support structure that receives the light from the display, wherein the lens module comprises first and second flexible membranes, wherein the first flexible membrane has linear stiffness variation in a first direction, and wherein the second flexible membrane has linear stiffness variation in a second direction that is perpendicular to the first direction; and   control circuitry configured to control the lens module to adjust curvature of the first flexible membrane and curvature of the second flexible membrane for astigmatism correction.   
     
     
         12 . The system defined in  claim 11 , wherein the lens module further comprises a first fluid-filled chamber at least partially defined by the first flexible membrane. 
     
     
         13 . The system defined in  claim 12 , wherein the lens module further comprises a second fluid-filled chamber at least partially defined by the second flexible membrane. 
     
     
         14 . The system defined in  claim 13 , wherein the control circuitry is configured to change a first amount of fluid in the first fluid-filled chamber and a second amount of fluid in the second fluid-filled chamber to adjust the curvature of the first flexible membrane and the curvature the second flexible membrane. 
     
     
         15 . The system defined in  claim 11 , wherein the lens module further comprises:
 actuators around a periphery of the first flexible membrane, wherein the control circuitry is configured to control the actuators to dynamically adjust the curvature of the first flexible membrane.   
     
     
         16 . A system, comprising:
 a head-mounted support structure;   a display that emits light; and   a lens module supported by the head-mounted support structure that receives the light from the display, wherein the lens module includes a fluid-filled chamber, a semi-rigid lens element that at least partially defines the fluid-filled chamber, and at least one actuator configured to selectively bend the semi-rigid lens element.   
     
     
         17 . The system defined in  claim 16 , wherein the lens module further comprises a rigid lens element that at least partially defines the fluid-filled chamber, wherein the rigid lens element and the semi-rigid lens element are parallel in a first state in which the semi-rigid lens element is not bent by the at least one actuator, and wherein the rigid lens element and the semi-rigid lens element are not parallel in a second state and wherein the at least one actuator selectively bends the semi-rigid lens element in the second state. 
     
     
         18 . The system defined in  claim 16 , wherein the lens module further comprises a rigid lens element that at least partially defines the fluid-filled chamber and wherein the lens module further comprises a tunable spherical lens and wherein the rigid lens element is interposed between the tunable spherical lens and the semi-rigid lens element. 
     
     
         19 . The system defined in  claim 16 , wherein the semi-rigid lens element has a spherically convex surface and a spherically concave surface in a first state in which the semi-rigid lens element is not bent by the at least one actuator and wherein the lens module further comprises a tunable spherical lens that is configured to offset a parasitic spherical lens power generated by the semi-rigid lens element in a second state in which the semi-rigid lens element is bent by the at least one actuator. 
     
     
         20 . The system defined in  claim 16 , wherein the at least one actuator comprises more than four actuators that are evenly distributed around a periphery of the semi-rigid lens element, wherein the lens module further comprises a load-spreading ring that extends around the periphery of the semi-rigid lens element, and wherein the semi-rigid lens element is formed from a material that has a Young's modulus greater than 2 GPa.