Liquid Lens Voice Coil Motor for Precise AF and OIS Control
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Solution Overview
Problem
Conventional lens drive devices for liquid lenses struggle to precisely control displacement and deformation, leading to inadequate auto focus and optical image stabilization performance.
Innovation Solution
A voice coil motor with multiple sub-motor parts, including a movable part, connection elastic piece, and drive circuit, is designed to independently control each sub-motor, allowing precise movement and deformation of the liquid lens along the optical axis, enabling effective auto focus and optical image stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single motor assembly is used to drive the liquid lens for both AF and OIS, then the device complexity is reduced, but the control precision over liquid lens displacement and deformation deteriorates
Solution Approach 1:
The motor assembly is divided into multiple independent sub-motor parts, each capable of independent control. This segmentation allows precise control over different aspects of liquid lens deformation while maintaining a relatively simple overall structure. Each sub-motor part can be independently actuated to achieve specific focusing or stabilization effects.
Solution Approach 2:
The connection elastic piece is designed with anisotropic stiffness characteristics, being more flexible in the direction perpendicular to the optical axis and stiffer in the optical axis direction. This dynamic flexibility allows the system to achieve both AF and OIS functions with a single motor assembly while maintaining control precision through differential stiffness control.
2Measurement precision
If the connection elastic piece has high stiffness in the optical axis direction, then the movable part can move in a single direction for precise control, but the flexibility for deformation control is reduced
Solution Approach 1:
The connection elastic piece is designed with non-uniform stiffness distribution, being stiffer in the optical axis direction and more flexible in the perpendicular direction. This local quality differentiation allows the structure to maintain positional accuracy along the optical axis while providing sufficient flexibility for the liquid lens deformation required by both AF and OIS operations.
Solution Approach 2:
The stiffness coefficients of the connection elastic piece are specifically engineered to have different values in different directions (anisotropic stiffness). By changing the stiffness parameter selectively in different spatial directions, the system achieves both precise displacement control and adequate deformation flexibility simultaneously.
3Measurement precision
If multiple sub motor parts are used with independent control, then the control precision is improved, but the device complexity increases
Solution Approach 1:
The motor assembly is divided into multiple independent sub-motor parts, each capable of independent control. This segmentation allows precise control over different aspects of liquid lens deformation while maintaining a relatively simple overall structure. Each sub-motor part can be independently actuated to achieve specific focusing or stabilization effects.
Solution Approach 2:
The multiple sub-motor parts share common structural elements and control mechanisms, allowing them to perform both AF and OIS functions through different actuation patterns. This multi-functionality reduces the overall complexity compared to having separate dedicated motors for each function.
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 voice coil motor achieves precise control over the liquid lens, enhancing both auto focus and optical image stabilization by ensuring accurate displacement and deformation, improving imaging quality.
Implementation Method 1
a coil and a circuit board that are fastened on the motor base part, where the coil is fastened on the circuit board and is electrically connected to the circuit board; and the movable part includes a magnet disposed opposite to the coil
Data Source
Figure 1(a)~1(d)
Figure 2
Figure 3
AI summary
This application provides a voice coil motor for driving a liquid lens and a lens assembly having a voice coil motor. The voice coil motor includes a plurality of sub motor parts. The plurality of sub motor parts can be independently controlled. The sub motor part includes: an unmovable part; a movable part, which can move along an optical axis direction relative to the unmovable part; a connection elastic piece, connected to a liquid lens and the movable part, where when a force is applied to the movable part in the optical axis direction, the movable part drives the connection elastic piece to squeeze the liquid lens, the connection elastic piece is a plate spring, and a stiffness coefficient of the connection elastic piece in the optical axis direction is greater than a stiffness coefficient of the connection elastic piece in a direction perpendicular to the optical axis direction; and a drive circuit part, configured to control a moving distance of the movable part. The voice coil motor in the foregoing technical solution can accurately implement auto focus and optical image stabilization of the liquid lens.