Camera Module Position Detection Using Magnet Poles and Neutral Zones
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Solution Overview
Problem
The increasing complexity and size of camera modules in portable electronic devices due to added features like autofocusing and optical image stabilization require more accurate detection of lens barrel movement in the optical axis direction, which existing technologies struggle to achieve efficiently.
Innovation Solution
A camera module design incorporating a fixed and movable portion with at least two position detection sensors and a magnet having N-pole, S-pole, and neutral zones, where the sensors are positioned to detect the magnet's poles and neutral zone, allowing for precise movement detection using sensing values that form sine or cosine curves and arctangent values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the amount of movement of the lens module in the optical axis direction is increased to support autofocusing and zoom functions, then the zoom function and autofocusing range are improved, but the position detection accuracy deteriorates due to the larger movement range
Solution Approach 1:
The magnet is divided into multiple magnetic poles (N-pole and S-pole) with distinct regions, and multiple position detection sensors are arranged at different positions. This segmentation allows each sensor to detect specific magnetic field regions, enabling accurate position detection across the entire large movement range through combined sensor outputs.
Solution Approach 2:
The position detection system transitions from one-dimensional detection to two-dimensional detection by arranging sensors both in the optical axis direction and in the direction intersecting the optical axis. This multi-dimensional sensor arrangement enables comprehensive position detection throughout the extended movement range while maintaining accuracy.
2Measurement precision
If multiple position detection sensors are added to improve position detection accuracy over large movement ranges, then position detection accuracy is improved, but the device complexity increases
Solution Approach 1:
The magnet structure serves multiple functions: it provides the driving magnetic field for the voice coil motor and simultaneously serves as the position detection target. The N-pole and S-pole regions are designed to both generate magnetic force and create detectable magnetic field patterns for position sensing, reducing the need for separate detection components.
Solution Approach 2:
The magnetic field generated by the magnet's N-pole and S-pole structure automatically provides position detection information to the sensors during normal operation. The same magnetic field that drives the voice coil motor also enables position sensing, allowing the system to self-monitor position without requiring additional active components.
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 design enables more accurate and efficient detection of the lens barrel's position, supporting wider range movements for autofocusing and zoom functions while maintaining a slim module size, ensuring sufficient driving force for focusing.
Implementation Method 1
a magnet disposed to oppose the at least two position detection sensors in a direction intersecting the optical axis direction. The magnet includes an N-pole and an S-pole on a surface opposing the at least two position detection sensors and a neutral zone between the N-pole and the S-pole
Data Source
AI summary
A camera module includes a fixed portion, a movable portion configured to be moved relative to the fixed portion in an optical axis direction, at least two position detection sensors, and a magnet disposed to oppose the at least two position detection sensors in a direction intersecting the optical axis direction. The magnet includes an N-pole and an S-pole on a surface opposing the at least two position detection sensors and a neutral zone between the N-pole and the S-pole. The at least two position detection sensors are disposed such that at least one position detection sensor opposes one of the N-pole and the S-pole and at least one other positon detection sensor opposes the neutral zone when the movable portion is moved in the optical axis direction.