Flexure-Amplified Piezo Actuator for Temperature-Stable Camera Focus

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

High-resolution cameras in autonomous vehicles face image focus capability issues due to temperature-induced fluctuations in the distance between the image sensor and the lens, affecting their performance across a wide temperature range.

Innovation Solution

A camera focus adjustment device utilizing a piezoelectric actuator wedged into a flexure structure, which adjusts the image sensor's position relative to the lens through temperature-dependent displacement, maintaining optimal focus by offsetting distance fluctuations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the image sensor is positioned within a threshold distance from the lens to provide focus capability, then image focus capability is improved, but the distance fluctuates with temperature changes causing focus degradation

Engineering Contradiction:

Improveimage focus capabilityVSAvoidambient temperature range

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent applies thermal expansion/contraction principles by using a piezoelectric actuator that expands when heated and contracts when cooled. This actuator is integrated into a flexure mechanism that converts the piezoelectric material's dimensional changes into precise movements of the image sensor, thereby compensating for temperature-induced focus drift. The flexure structure itself also utilizes thermal expansion characteristics to amplify the piezoelectric displacement effect.

Inventive Principle:

Principle #37Thermal expansion

Solution Approach 2:

The patent changes physical parameters by using piezoelectric material that undergoes dimensional parameter changes (expansion/contraction) in response to temperature variations. The flexure mechanism transforms these parameter changes into controlled positional adjustments of the image sensor, maintaining optimal focus distance despite ambient temperature fluctuations.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a traditional focus adjustment mechanism is used to compensate for temperature fluctuations, then focus stability is improved, but device complexity and power consumption increase

Engineering Contradiction:

Improvefocus stabilityVSAvoidmechanical moving parts

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces traditional mechanical focus adjustment mechanisms (such as motors, gears, and actuators) with a piezoelectric-based system. The piezoelectric actuator, integrated with a flexure mechanism, provides focus adjustment through material property changes rather than mechanical moving parts, thereby reducing device complexity while maintaining focus stability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The piezoelectric actuator operates passively in response to temperature changes, utilizing the temperature-induced piezoelectric effect to automatically compensate for focus drift. This self-service mechanism eliminates the need for external power sources or control systems, reducing both power consumption and device complexity while maintaining reliable focus adjustment.

Inventive Principle:

Principle #25Self-service

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

The device ensures a consistent image focus capability across a large temperature range by compensating for thermal expansions and contractions, enhancing the camera's performance without the need for power or moving parts, thus improving focus stability and power efficiency.

Implementation Method 1

Contraction of the piezoelectric material, based on an increased temperature, can cause displacement (e.g., expansion in the vertical direction) of the flexure structure

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

the distance between the image sensor and the lens can fluctuate based on temperature. For example, the distance between the image sensor and the lens may expand in warmer temperatures

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

The flexure structure may include an outer framework of structural members that are interconnected using flexure notch hinges

Methodology Applied

Scientific EffectFlexure mechanism: Hinge

Data Source

PatentUS12200337B2Flexure amplified piezo actuator for focus adjustment

Publication Date: 2025.01.14 WAYMO LLC

AI summary

A camera includes a camera focus adjustment device, a lens, and an image sensor coupled to the camera focus adjustment device. The camera focus adjustment device includes a flexure structure. The flexure structure includes an outer framework of structural members continuously interconnected by flexure notch hinges. The flexure structure also includes two inner structural members oriented in parallel and extending from the outer framework of structural members. A gap is between the two inner structural members. The camera focus adjustment device also includes a piezoelectric material within the gap and a pair of wedges within the gap. The pair of wedges is affixed to the piezoelectric material and to one inner structural member of the two inner structural members. Based on temperature-based piezoelectric activity associated with the piezoelectric material, the camera focus adjustment device is operable to move the image sensor relative to the lens.