Actuator Driver Crosstalk Correction via Radial Distance Mapping
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Solution Overview
Problem
Existing camera modules face challenges in accurately correcting crosstalk errors in autofocus position detection signals due to misalignment between the center of the position detection magnet and the magnetosensitive unit of the Hall element, caused by assembly variations and dimensional tolerances, which complicates the correction process.
Innovation Solution
A method and actuator driver that displace the movable unit in two-axis directions to detect peak position signals, store reference positions and correction information, and generate correction amounts to adjust the position detection signals, effectively converting two-dimensional displacement into a one-dimensional radius for simplified crosstalk correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If crosstalk correction is performed using two-dimensional distribution in the XY plane when magnet center and magnetosensitive unit are misaligned, then measurement precision is improved, but device complexity increases significantly
Solution Approach 1:
The patent transforms the two-dimensional XY plane correction problem into a one-dimensional radial distance correction by introducing the radial dimension. By calculating the radial distance between the magnet center and magnetosensitive unit and using pre-measured correction values corresponding to different radial distances, the system simplifies the correction process while maintaining high precision AF position detection even when misalignment occurs.
2Adaptability or versatility
If the center of the position detection magnet is not located right above the magnetosensitive unit due to assembly variations, then manufacturing adaptability is improved, but measurement precision deteriorates
Solution Approach 1:
The patent performs preliminary measurement and storage of correction values during the manufacturing process. By measuring the magnetic field distribution in advance and storing correction values corresponding to different radial distances in a table, the system prepares the necessary correction data before actual operation. This preliminary action enables the system to adapt to assembly variations without compromising AF position detection precision during use.
Solution Approach 2:
The patent changes the correction approach from fixed two-dimensional XY plane correction to dynamic radial distance-based correction. By calculating the radial distance parameter and selecting correction values based on this parameter from a pre-measured table, the system adapts to different alignment conditions while maintaining measurement precision across various assembly variations.
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 approach allows for accurate crosstalk correction even when the magnetosensitive unit is misaligned, reducing the complexity of the correction process and ensuring precise autofocus and image stabilization operations.
Implementation Method 1
a Hall element for detecting a change in magnetic field is disposed on a fixed unit
Data Source
AI summary
An image stabilization actuator is used to displace a movable unit in a first direction, and a position in the first direction when an AF-axis position detection signal reaches a peak value is detected. Similarly, the image stabilization actuator is used to displace the movable unit in a second direction, and a position in the second direction when the AF-axis position detection signal reaches a peak value is detected. A reference position based on the position in the first direction and the position in the second direction thus obtained is stored. Correction information indicating a relationship between a displacement amount, from the reference position, of the movable unit displaced by the image stabilization actuator and a correction amount of the position detection signal is stored.