Lens Driving Device Isolating Orthogonal Position Detection
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Solution Overview
Problem
Existing lens driving devices suffer from reduced precision in correcting image shake due to cross-detection by position sensors, which affects the accuracy of hand movement correction.
Innovation Solution
A lens driving device with a base member, a movable member, a first driving portion, a lens frame, and Hall elements, where the Hall elements detect changes in the magnetic field caused by the movable member's orthogonal movement, maintaining constant distance and reducing part count, allowing precise image shake correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a movable member rotates around two orthogonal reference axes with position sensors for each axis, then the lens barrel can be positioned to correct image distortion, but the position sensors may detect positions in both axes directions causing cross-detection and reducing correction precision
Solution Approach 1:
The position detection function is segmented into two independent systems: (1) optical sensors detect only the rotational position around the first reference axis, and (2) Hall elements detect only the positional deviation in the second axis direction. This segmentation eliminates cross-detection between axes, allowing each sensor to measure only its designated parameter without interference from the other axis's movement.
Solution Approach 2:
A magnet is introduced as an intermediary element that couples the movable member's position to the Hall elements. The magnet moves with the movable member in the second axis direction, and the Hall elements detect the magnet's position to determine the movable member's deviation. This intermediary enables independent detection of the second axis position without affecting the optical sensors' measurement of the first axis rotation.
2Measurement precision
If separate magnets are used for driving the lens frame and for detecting movable member position, then detection precision is improved, but the number of parts increases and device size grows
Solution Approach 1:
The magnet serves multiple functions simultaneously: (1) it acts as a driving element interacting with the coil to move the lens frame in the optical axis direction, and (2) it serves as a detection target for the Hall elements to detect the movable member's position in the second axis direction. By making the magnet universal and multi-functional, the patent eliminates the need for separate magnets for driving and detection, reducing the total number of parts while maintaining detection precision.
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
Enables precise correction of image shake by isolating orthogonal movement detection, reducing the device's size and part count, and allowing common use of magnets for driving and detection.
Implementation Method 1
a Hall element that is disposed so as to oppose the first magnet in the direction of the optical axis and that detects a change in a magnetic field of the first magnet
Implementation Method 2
a second driving portion that moves the lens frame in the direction of the optical axis and that includes a first magnet that is secured to the movable member and a first coil that is secured to the lens frame
Data Source
AI summary
A lens driving device includes a base member, a movable member that is disposed at the base member and moves in a plane that is orthogonal to an optical axis, a first driving portion that moves the movable member in a direction that is orthogonal to the optical axis in accordance with image shake, a lens frame that is mounted to the movable member and moves in a direction of the optical axis, a second driving portion that moves the lens frame in the direction of the optical axis and includes a first magnet that is secured to the movable member and a first coil that is secured to the lens frame, and a Hall element that is disposed so as to oppose the first magnet in the direction of the optical axis and detects a change in a magnetic field of the first magnet.