Elliptical Piezoelectric Actuator Torque in Compact Lens Barrels
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As digital cameras and lens barrels become more compact, the limited space available for vibration actuators results in a reduction in the diameter of the vibrating element, leading to a decrease in generated torque, compromising drive performance.
Innovation Solution
A vibration actuator design featuring a piezoelectric body with an elliptical shape, where the thickness varies along the relative movement direction, and electrode portions are formed to maintain constant electrostatic capacity, allowing for maximum torque generation in constrained spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the vibration actuator is made smaller to fit limited space, then the space requirement is reduced, but the diameter of the vibrating element becomes smaller and the generated torque decreases
Solution Approach 1:
The piezoelectric body employs variable thickness distribution, being thicker at the major axis sides and thinner at the minor axis sides of the elliptical shape. This local quality variation allows the driving surface to generate sufficient elliptical motion amplitude for high torque while keeping the overall actuator size compact. The non-uniform thickness optimizes the vibration characteristics locally to maintain torque output despite reduced overall dimensions.
Solution Approach 2:
The piezoelectric body has an elliptical cross-section rather than a circular one, with the thickness varying asymmetrically along different axes. This asymmetric geometry allows the actuator to generate effective elliptical motions at the driving surface while maintaining a compact form factor. The elliptical shape with varied thickness distributes the piezoelectric material optimally to produce high torque in a limited space.
2Force
If the piezoelectric body thickness is increased to generate higher torque, then the generated torque increases, but the overall size of the vibration actuator increases
Solution Approach 1:
Instead of uniformly increasing the piezoelectric body thickness, the invention applies variable thickness locally where needed - thicker at the major axis sides to generate sufficient vibration amplitude for high torque, and thinner at the minor axis sides to maintain compact overall dimensions. This localized optimization resolves the contradiction between torque generation and size reduction.
Solution Approach 2:
The invention transitions from a circular symmetric design to an elliptical asymmetric design with thickness variation in multiple dimensions. By utilizing the elliptical geometry with different thicknesses along major and minor axes, the actuator optimizes torque generation in the radial dimension while controlling the overall volume through strategic thickness distribution.
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 vibration actuator achieves excellent drive performance and can be arranged in limited spaces, providing a stable driving force by ensuring consistent progressive wave generation and contact between the moving element and the vibrating element, even in compact designs.
Implementation Method 1
A vibration actuator utilizes expansions and contractions of a piezoelectric body to generate progressive oscillation waves at a driving surface of an elastic body
Data Source
AI summary
Disclosed is a vibration actuator which can be arranged in a limited space, and which has excellent drive performance. Also disclosed are a lens barrel and a camera, which are provided therewith. Specifically disclosed is a vibration actuator which includes: a piezoelectric body which has a first surface, and which is excited by an electrical signal; a vibration body which is joined to the first surface, and which has a second surface on which vibration waves are generated by the excitation; and a moving body which is brought into pressure contact with the second surface, and which moves relatively to the vibration body, wherein the thickness of the piezoelectric body is different in the direction of the relative movement of the moving body.