Voice Coil Motor Actuator for Miniature Camera Autofocus
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Solution Overview
Problem
Current miniature camera solutions for small form-factor devices, such as smartphones and computers, face challenges with excessive heat generation during autofocus engagement, which is exacerbated by the lack of cooling periods in typical usage scenarios, affecting the performance and reliability of these devices.
Innovation Solution
The proposed solution involves an actuator module with a voice coil motor base, a coil rigidly attached to the base, a lens movement mechanism suspended by a suspension means to limit orthogonal motion, and a plurality of magnets mounted to the lens movement mechanism, which generates controlled motion using Lorentz forces to adjust the lens position relative to the image sensor, while also incorporating a metallic component for heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voice coil motor with coil and magnets is used for autofocus in miniature cameras, then the lens position can be adjusted along the optical axis, but excessive heat is generated during prolonged autofocus engagement
Solution Approach 1:
The patent extracts the heat-generating coil from the moving lens assembly and mounts it rigidly to the stationary voice coil motor base. Only the magnets are attached to the lens movement mechanism, separating the thermal source from the thermally sensitive autofocus components. This extraction reduces heat transfer to the lens and image sensor while maintaining autofocus functionality.
Solution Approach 2:
The patent introduces a suspension means as an intermediary between the lens movement mechanism and the voice coil motor base. This suspension system limits orthogonal motion while allowing axial movement for autofocus, and acts as a thermal barrier that reduces heat transfer from the coil to the lens assembly.
2Volume of moving object
If the camera is miniaturized for small form-factor devices, then the device size is reduced, but heat dissipation becomes more difficult
Solution Approach 1:
By extracting the coil from the moving lens assembly and mounting it to the stationary base, the patent creates a dedicated heat source location that can be thermally managed. This separation allows for more efficient heat dissipation paths in the miniaturized camera structure, as the heat-generating coil is isolated from the compact lens and sensor assembly.
Solution Approach 2:
The patent applies different mounting configurations to different components: the coil is rigidly mounted to the base for thermal stability and heat dissipation, while the magnets are mounted to the moving lens mechanism. This local differentiation of mounting quality optimizes both thermal management and mechanical functionality in the miniaturized design.
3Speed
If the coil is rigidly attached to the voice coil motor base, then the lens can be moved along the optical axis with controlled Lorentz forces, but heat is retained in the actuator module
Solution Approach 1:
The patent extracts the coil from the moving assembly and fixes it to the base, creating a stationary electromagnetic field source. This extraction allows the lens to be moved by magnetic forces alone without the coil heating the moving components, improving both speed control and thermal management.
Solution Approach 2:
The patent replaces a traditional mechanical motor system with a voice coil motor that uses electromagnetic Lorentz forces for lens actuation. This substitution enables precise, controlled lens movement along the optical axis while generating less mechanical friction and heat in the moving parts compared to conventional motors.
4Ease of operation
If magnets are mounted to the lens movement mechanism, then the lens position can be adjusted, but the structure becomes more complex
Solution Approach 1:
The patent merges the autofocus function with the optical image stabilization function by using the same voice coil motor assembly and suspension means. The magnets mounted to the lens movement mechanism enable both autofocus (through electromagnetic interaction with the base coil) and OIS (through controlled interaction with additional coils), reducing overall system complexity despite the added mounting requirements.
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 configuration enhances thermal performance by effectively managing heat dissipation and maintaining reliable autofocus functionality, even during prolonged engagement, thereby improving the overall performance and durability of small form-factor cameras.
Implementation Method 1
a coil rigidly attached to the voice coil motor base... a plurality of magnets rigidly mounted to the lens movement mechanism
Data Source
AI summary
In some embodiments, the actuator module includes an voice coil motor base, a coil rigidly attached to the voice coil motor base, a lens movement mechanism suspended on the voice coil motor base by a suspension means configured to limit relative motion in linear directions orthogonal to an optical axis of the miniature camera, and a plurality of magnets rigidly mounted to the lens movement mechanism.