Abstract: A head-mounted device may have a lens module with a tunable lens. The tunable lens may include a lens element and one or more actuators that control the shape of the lens element. The actuators may be locally controlled or globally controlled. The actuators may be globally controlled by a common shape memory alloy wire. The common shape memory alloy wire may be wrapped around a pulley system and/or routed about a suitable portion of the head-mounted device. Each actuator may include one or more wedge-shaped structures. Each actuator may include a flexure that is attached between a chassis and a lens shaping element. Each actuator may include a pivot assembly and a brake assembly.

Abstract: A head-mounted device may have a lens module with a tunable lens. The tunable lens may include a fluid-filled chamber interposed between first and second lens elements. The tunable lens may include one or more actuators that control the shape of the first lens element. To mitigate the total actuation energy associated with the one or more actuators, the tunable lens may include bellows structures that are in tension for some or all of the displacement range of the lens shaping element, a pre-deformed lens shaping element, a magnetic negative stiffness element, a bistable springs negative stiffness mechanism, a cam roller negative stiffness mechanism, and/or a torsion spring.

Abstract: An electronic device may include a lens module with a tunable lens. The tunable lens may include a flexible lens element and a lens shaping structure attached to the flexible lens element. The lens shaping structure may include a plurality of tabs that are each coupled to a respective actuator. The actuator may move the tab up and down along an axis of displacement. The actuator may have a structure that is configured to rotate about a pivot structure. At least one shape memory alloy (SMA) wire may be attached to an upper portion of the structure and at least one SMA wire may be attached to a lower portion of the structure. The SMA wires may be controlled to selectively rotate the structure, thereby controlling the position of a tab along the axis of displacement.

Abstract: An electronic device may include a lens module with a tunable lens. The tunable lens may include multiple adjustable fluid-filled bladders distributed around the periphery of the tunable lens. Fluid may be selectively added to and removed from each adjustable fluid-filled bladder to control a displacement of a lens element at a given position along the periphery. The fluid may be added to and removed from the adjustable fluid-filled bladders by fluid-controlling components. The fluid-controlling components may be positioned locally within a ring-shaped chassis portion and adjacent to a respective bladder or may be consolidated in an additional chassis portion and connected to the bladders using fluid channels through the ring-shaped chassis portion. The fluid-controlling components may include stepper motors with two subassemblies that each have a ring-shaped magnet between two coils.