Tunable Lens Pivoting SMA Actuators for User-Specific Adjustment

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Solution Overview

Problem

Head-mounted devices often have lenses with fixed shapes and properties, making it difficult to adjust them optimally for each user.

Innovation Solution

Incorporation of a pivot structure with shape memory alloy (SMA) wires and a brake assembly to selectively adjust the position of a conductive lens shaping element, allowing for tunable lens configurations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If fixed shape lenses are used in head-mounted devices, then the device structure is simple and reliable, but the lens cannot be adjusted optimally for different users

Engineering Contradiction:

Improvelens adjustabilityVSAvoiddevice structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies the dynamics principle by transforming the fixed lens system into a dynamic, adjustable system. Shape memory alloy actuators enable the lens to change its shape and position dynamically, allowing optimization for different users while maintaining a relatively simple overall device structure through controlled transformation rather than complete redesign.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements parameter changes by utilizing shape memory alloy materials that undergo phase transformations to alter their physical state. This enables the lens parameters (shape, position, curvature) to be changed on demand through temperature or stress-induced phase changes in the SMA actuators, providing adjustability without complex mechanical structures.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If shape memory alloy actuators are added to enable lens adjustment, then lens customizability is improved, but the device complexity increases

Engineering Contradiction:

Improvelens customizationVSAvoidactuator mechanism

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies mechanics substitution by replacing traditional mechanical adjustment mechanisms (motors, gears, linkages) with shape memory alloy actuators that use material phase transformations to achieve the same functional outcome. This substitution reduces the complexity of the actuator mechanism while enabling lens customization, as SMAs provide direct shape change without complex mechanical transmission systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent utilizes phase transitions in shape memory alloy materials to achieve actuation. The SMA wires undergo martensitic phase transformations when exposed to specific temperatures or stress conditions, causing them to change shape and apply force to adjust the lens. This phase transition mechanism provides a simple, direct way to achieve lens adjustment without complex mechanical actuation systems.

Inventive Principle:

Principle #36Phase transitions

3Manufacturing precision

If multiple actuators are distributed around the lens periphery, then the lens shaping precision is improved, but the manufacturing complexity increases

Engineering Contradiction:

Improvelens shaping precisionVSAvoidassembly process

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent applies segmentation by dividing the lens adjustment system into multiple distributed actuators positioned around the periphery. Each actuator independently controls a specific region of the lens, allowing precise shaping through coordinated action. This segmentation enables high precision lens shaping while simplifying the manufacturing process, as each modular actuator unit can be produced and assembled independently rather than requiring a single complex mechanism.

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables customizable lens adjustments to optimize content presentation for individual users, enhancing user experience and adaptability.

Implementation Method 1

at least one shape memory alloy wire that is configured to selectively rotate the structure about the pivot structure

Methodology Applied

Scientific EffectShape memory alloy: Shape Memory Alloy

Implementation Method 2

at least one shape memory alloy wire that is configured to selectively pull the conductive structure

Methodology Applied

Scientific EffectShape memory alloy: Shape Memory Alloy

Data Source

PatentUS20250355240A1Tunable Lens with Pivoting Shape Memory Alloy Actuators

Publication Date: 2025.11.20 APPLE INC

AI summary

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.