Autofocus Actuator Using Piezoelectric Compensation
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Solution Overview
Problem
Conventional optical systems face challenges in maintaining image sensor alignment with lenses over a wide temperature range due to thermal expansion, leading to defocusing and optical aberrations, which existing passive athermalization methods cannot fully mitigate.
Innovation Solution
An active compensation system using a piezoelectric structure is introduced between the lens holder and the image sensor substrate, allowing for dynamic adjustment of the image sensor's position to maintain focus over a predetermined temperature range, incorporating a piezoelectric tube or linear actuators to compensate for thermal focus shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If passive athermalization methods are used to compensate for thermal expansion, then manufacturing complexity is reduced, but the ability to maintain focus over wide temperature ranges deteriorates
Solution Approach 1:
The patent replaces passive mechanical athermalization structures with an active piezoelectric actuation system. The piezoelectric actuator converts electrical signals into precise mechanical displacements to dynamically adjust the image sensor position, compensating for thermal focus shifts that passive structures cannot correct across wide temperature ranges.
Solution Approach 2:
The system changes the physical state by applying voltage to the piezoelectric actuator, which undergoes dimensional changes (expansion/contraction) in response to electrical fields. This allows dynamic adjustment of the image sensor position to maintain focus as temperature varies, overcoming the limitations of fixed passive athermalization designs.
2Reliability
If active compensation systems with piezoelectric structures are implemented, then focus maintenance over temperature ranges is improved, but device complexity increases
Solution Approach 1:
The piezoelectric actuator serves multiple functions: it acts as both the compensation mechanism for thermal focus shifts and the positioning actuator for autofocus. The control system integrates temperature sensing, piezoelectric actuation, and focus control into a unified system that handles both athermalization and autofocus requirements, reducing the need for separate dedicated components.
Solution Approach 2:
The piezoelectric actuator functions as an intermediary element between the control electronics and the image sensor positioning system. It translates electrical control signals into precise mechanical displacements, enabling fine control of the image sensor position to compensate for thermal effects without requiring direct mechanical linkages or complex transmission mechanisms.
3Reliability
If the image sensor position is dynamically adjusted using piezoelectric actuators, then thermal focus shift is compensated, but manufacturing precision requirements increase
Solution Approach 1:
The piezoelectric actuator system provides self-adjustment capability, automatically compensating for thermal focus shifts without requiring manual intervention or complex mechanical adjustment mechanisms. The system senses temperature changes and autonomously actuates to maintain focus, reducing the need for high-precision manual assembly and field adjustments.
Solution Approach 2:
The system transitions from static mechanical positioning to dynamic piezoelectric actuation. The image sensor position can be continuously adjusted in real-time in response to temperature changes, replacing rigid precision-machined mechanical linkages with flexible, controllable piezoelectric elements that can adapt to thermal conditions.
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
This solution effectively maintains the image sensor at the focal plane across a temperature range of -30 to 65°C, reducing thermal focus shift impacts and enhancing optical system stability and performance.
Implementation Method 1
an active compensation system having a piezoelectric structure coupled between the lens holder and the first surface of the substrate
Implementation Method 2
Conventional optical systems face challenges in maintaining image sensor alignment with lenses over a wide temperature range due to thermal expansion
Data Source
AI summary
The present disclosure relates to systems, vehicles, and methods that include adjusting a position of an image sensor with respect to a lens assembly. An example optical system includes a lens assembly having at least one lens. The at least one lens defines an optical axis, a focal distance, and a focal plane. The optical system also includes a lens holder coupled to the lens assembly and a substrate having a first surface. The optical system additionally includes an image sensor attached to the first surface of the substrate. Furthermore, the optical system includes an active compensation system having a piezoelectric structure coupled between the lens holder and the first surface of the substrate. The active compensation system is configured to maintain the image sensor at the focal plane over a predetermined temperature range.