Segmented Lens Drive Coil Layout for Higher Focusing Thrust
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Solution Overview
Problem
Conventional linear motor configurations, such as those disclosed in Patent Literature 1, face limitations in increasing thrust force to effectively drive heavier lenses, necessitating further improvements to accommodate larger and more massive imaging elements.
Innovation Solution
The proposed lens drive unit incorporates n-phase coils and a first field portion with N poles and S poles alternately disposed along the optical axis. The coils are arranged in two or more sets side by side, each set being n-phase coils with respect to one of the field portions, allowing for increased thrust by optimizing the magnetic circuit configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional linear motor configuration is used, then the structure is simple, but the thrust force is insufficient to drive heavier lenses
Solution Approach 1:
The linear motor is divided into multiple independent coil sets (first set, second set, third set, etc.) arranged along the optical axis. Each coil set can be controlled independently and contributes to the total thrust force, allowing the system to generate higher thrust by combining the forces from multiple segmented coil units.
Solution Approach 2:
The coil sets are arranged in the optical axis direction (longitudinal dimension) rather than only in the radial direction. This dimensional arrangement allows multiple coil sets to contribute additively to the thrust force along the optical axis, effectively increasing the motor's thrust capability without proportionally increasing the radial space required.
2Weight of moving object
If the lens mass is increased to achieve larger imaging elements, then the imaging performance is improved, but the thrust requirement increases beyond conventional motor capabilities
Solution Approach 1:
Multiple coil sets are merged into a single integrated motor structure that works together to drive the lens. The combined thrust from all coil sets (first set, second set, third set, and fourth set) provides sufficient force to move heavier lenses with larger imaging elements, overcoming the limitation of conventional single-coil or fewer-coil configurations.
3Force
If magnets are disposed along the optical axis to sandwich the coils, then the thrust is increased, but the magnetic circuit becomes more complex
Solution Approach 1:
The magnetic circuit is segmented into multiple field portions, each associated with a specific coil set. The first field portion corresponds to the first coil set, the second field portion to the second coil set, and so on. This segmentation allows each magnet assembly to be optimized independently while contributing to the overall thrust through coordinated operation of all segments.
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 achieves higher thrust compared to previous designs, enabling the smooth operation of heavier lenses by effectively increasing the thrust force while maintaining a compact design.
Implementation Method 1
n-phase coils and a first field portion... The coils are disposed in two or more sets side by side in the optical axis direction... achieves higher thrust
Data Source
AI summary
A lens drive unit comprises two-phase coils and field units. The two-phase coils are fixed to a focusing lens frame that is able to move back and forth in the optical axis direction and holds a lens, and are disposed side by side along the optical axis direction. The field units have N poles and S poles that are disposed alternately along the optical axis direction. The coils are disposed in two or more sets side by side in the optical axis direction, with one set of two-phase coils for a field unit.