Roller-Guided Lens Actuator for Fast Stable Autofocus
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Solution Overview
Problem
Existing camera modules face challenges in miniaturization and performance enhancement, particularly in achieving fast autofocus operation and suppressing bobbin movement during autofocus, while also accommodating larger magnet and coil sizes.
Innovation Solution
A lens moving apparatus that incorporates a bobbin guided by rollers instead of a leaf spring, with a magnetic and coil system optimized for compact size and efficient movement, including a circuit board and magnetic body to enhance the autofocus mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a leaf spring is used to guide the bobbin, then the structure is simple, but the autofocus speed is slow and bobbin movement cannot be suppressed
Solution Approach 1:
The patent replaces the leaf spring mechanical guiding system with a roller-based guiding system. The rollers reduce friction between the bobbin and the guiding structure, enabling faster bobbin movement during autofocus operation while maintaining structural guidance. This mechanical substitution directly addresses the contradiction by improving autofocus speed without excessive complexity increase.
Solution Approach 2:
The patent changes the friction parameter by introducing rollers with low-friction contact surfaces. The rollers convert sliding friction into rolling friction, significantly reducing resistance to bobbin movement. This parameter change enables faster autofocus response while the roller configuration maintains adequate structural guidance.
2Force
If the magnet and coil sizes are increased to improve driving force, then the autofocus performance improves, but the camera module size increases
Solution Approach 1:
The patent optimizes the magnetic field parameters by using high-strength rare-earth magnets and optimizing coil winding parameters. This allows achieving higher driving force density, enabling sufficient autofocus force with smaller overall magnet and coil dimensions, thus improving performance without proportionally increasing module size.
Solution Approach 2:
The patent employs composite magnetic structures combining different magnetic materials with optimized geometries. The use of high-coercivity magnetic materials allows for more efficient magnetic field generation in compact volumes, resolving the contradiction between driving force and size.
3Speed
If the bobbin is allowed to move freely during autofocus, then the movement speed increases, but unwanted bobbin movement and instability occur
Solution Approach 1:
The patent introduces rollers as intermediary elements between the bobbin and the housing guiding surfaces. These rollers mediate the interaction by providing controlled guidance while minimizing friction, allowing the bobbin to move quickly in the desired direction while preventing unwanted lateral or rotational movements through the roller's constrained contact geometry.
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 solution improves autofocus speed, suppresses bobbin movement, and allows for a wider range of magnet and coil sizes, enhancing the performance and miniaturization of camera modules.
Implementation Method 1
a coil disposed between the first post and the second post so as to correspond to the magnet
Data Source
AI summary
A lens moving apparatus includes a base comprising a body and a post extending upward from an upper surface of the body; a bobbin disposed on the body; a magnet disposed on the bobbin; and a coil disposed to correspond to the magnet and configured to move the bobbin in a direction parallel to an optical axis by an interaction with the magnet; and a rolling member disposed between the bobbin and the post of the base. The post includes a groove having an opening spaced from opposite ends of the groove, and the rolling member is disposed in the groove of the post, and the opening is configured to expose a portion of the rolling member. The bobbin includes a support extending into the opening so as to be in contact with the rolling member.