Lens Holder Driving Device with Hall Element Positioning
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Solution Overview
Problem
Existing lens holder driving devices for miniature cameras face challenges in stabilizing images without increasing size or complexity, particularly in miniaturizing image stabilizer structures like sensor shift and lens shift methods, which are unsuitable for mobile phones due to size and complexity issues.
Innovation Solution
A lens holder driving device that incorporates an auto-focusing lens holder driving portion and an image stabilizer portion, using a permanent magnet and focusing coil to move the lens holder along the optical axis, and an image stabilizer coil to stabilize images by moving the lens holder in orthogonal directions, with Hall elements positioned to avoid magnetic field interference and suspension wires secured to prevent fracturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensor shift method or lens shift method is used for image stabilization, then image quality is improved, but device size increases making it unsuitable for miniature cameras
Solution Approach 1:
The patent combines the autofocus driving structure and image stabilization structure into a single integrated system. The lens holder serves dual purposes: it moves the lens along the optical axis for autofocus while simultaneously being movable in orthogonal directions for image stabilization. This merging eliminates the need for separate sensor shift or lens shift mechanisms, achieving image stabilization with compact dimensions suitable for mobile phones.
Solution Approach 2:
The lens holder is designed with multi-functionality, serving both as the autofocus actuator platform and the image stabilizer. By making the lens holder movable in multiple directions (longitudinal for focus, lateral for stabilization), the system achieves dual functionality without requiring additional dedicated components for image stabilization, thus reducing overall device size.
2Device complexity
If software stabilizing method is used, then processing complexity is reduced, but taking time interval becomes longer due to software processing
Solution Approach 1:
The patent replaces software-based image stabilization with a hardware-based optical stabilization system. By using electromagnetic actuators to physically move the lens holder in orthogonal directions to counteract camera shake, the system achieves real-time stabilization without the time delays associated with software processing and post-processing operations.
3Measurement precision
If Hall elements are positioned close to coils for detection, then detection precision is improved, but magnetic field interference from coil current adversely affects detection accuracy
Solution Approach 1:
The patent extracts the Hall elements from the region affected by coil magnetic fields and positions them in a location where they can detect the position of the permanent magnet without being influenced by the alternating magnetic field generated by the coil current. This spatial separation eliminates the harmful magnetic field interference while maintaining detection functionality.
Solution Approach 2:
The permanent magnet serves as an intermediary between the coil and the Hall elements. The coil generates a magnetic field that acts on the permanent magnet, causing it to move, and the Hall elements detect the position of this permanent magnet. This intermediary arrangement allows indirect measurement of coil position without exposing the sensitive Hall elements to the harmful alternating magnetic field of the coil current.
4Ease of operation
If suspension wires are made flexible for movement, then ease of operation is improved, but reliability decreases due to risk of fracturing under impact
Solution Approach 1:
The patent employs suspension wires made from elastically deformable materials that combine flexibility with high strength. These composite or specially selected materials allow the wires to bend and accommodate movement while maintaining sufficient tensile strength to resist fracturing under impact loads, thus achieving both ease of operation and reliability.
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 effectively stabilizes images while maintaining a compact size, preventing suspension wire fractures, and enhancing impact resistance, allowing for efficient image stabilization in miniature camera systems.
Implementation Method 1
a permanent magnet 28 and a focusing coil 26 for moving the lens holder 24 in the direction of the optical axis O
Implementation Method 2
an image stabilizer coil 18 for moving the lens holder 24 in directions orthogonal to the optical axis O
Implementation Method 3
two Hall elements 50f, 50l for detecting the position of the auto-focusing lens holder driving portion 20
Implementation Method 4
four suspension wires 16 extending along the optical axis O and having first end portions 161 fixed to the fixed portion 13 and second end portions 162 fixed to the upper end portion of the auto-focusing lens holder driving portion 20
Data Source
AI summary
An AF unit of a lens holder driving device includes a lens holder, a focusing coil, a permanent magnet having a plurality of permanent magnet pieces having first surfaces opposed to the focusing coil, a magnet holder holding the permanent magnet, and first and second leaf springs supporting the lens holder in a direction of an optical axis shiftably. An image stabilizer portion includes a fixed portion disposed near the second leaf spring, a supporting member swingably supporting the AF unit with respect to the fixed portion, an image stabilizer coil having a plurality of image stabilizer coil portions disposed so as to oppose to second surfaces of the plurality of permanent magnet pieces that are perpendicular to the first surfaces, and a plurality of Hall elements. Each Hall element is disposed at a position where the image stabilizer coil portion is separated into a plurality of coil parts.