Magnetic Lens Carrier Position Sensing for Autofocus
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Solution Overview
Problem
Small form factor cameras face challenges in achieving high image quality due to unwanted motion, which is not accurately compensated by existing autofocus and optical image stabilization mechanisms, requiring improved position measurement techniques for precise lens control.
Innovation Solution
The implementation of a method using position sensor magnets and Hall sensors to generate and measure magnetic fields, allowing for accurate position measurement and feedback control of the camera lens carrier, enabling precise motion control orthogonal to the substrate and improving system resolution while minimizing external interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional autofocus mechanisms are used in small form factor cameras, then the camera can focus on objects at different distances, but the lens position measurement accuracy is insufficient leading to unwanted lens motion and degraded image quality
Solution Approach 1:
The patent replaces traditional mechanical position sensing mechanisms with a magnetic field-based sensing system. Hall sensors detect the position of the lens carrier by measuring magnetic field changes caused by magnets attached to the moving lens assembly, eliminating the need for complex mechanical encoders or potentiometers while achieving high measurement precision
Solution Approach 2:
The patent introduces magnets as an intermediary element attached to the lens carrier. These magnets create a magnetic field that serves as a mediator between the moving lens and the stationary Hall sensors, enabling non-contact position detection through magnetic field measurements
2Reliability
If optical image stabilization mechanisms are added to compensate for unwanted lens motion, then image quality can be improved, but the device complexity and parasitic motion increase
Solution Approach 1:
The patent implements a feedback control system where Hall sensors continuously measure the lens carrier position, and this position information is fed back to control algorithms that adjust the lens actuator to compensate for unwanted motion. This closed-loop feedback enables effective image stabilization without requiring additional complex stabilization hardware
Solution Approach 2:
The magnetic sensing system serves dual purposes: it provides both autofocus position detection and optical image stabilization measurements using the same sensors and magnets, eliminating the need for separate measurement systems and reducing overall device complexity
3Ease of operation
If the lens is moved as a single rigid body along the optical axis for autofocus, then focusing can be achieved, but parasitic motion in orthogonal directions occurs degrading image quality
Solution Approach 1:
The patent segments the lens system into a stationary camera body and a movable lens carrier assembly. By independently controlling the lens carrier's position along the optical axis while maintaining its orientation, the system achieves focus adjustment without introducing parasitic rotational or lateral motions that would degrade image quality
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 enhances the accuracy of autofocus and optical image stabilization, leading to improved image quality by accurately compensating for unwanted lens motion and reducing parasitic movements, thus stabilizing the image capture process.
Implementation Method 1
generating a measurement of a magnetic field resulting at least in part from the one or more position sensor magnets
Implementation Method 2
measuring the magnetic field component at a sensor fixedly mounted to the substrate of the autofocus actuator
Data Source
AI summary
Some embodiments include a method for measuring the position of a camera lens carrier moveable by an autofocus actuator. In some embodiments, the method includes generating a measurement of a magnetic field resulting at least in part from the one or more position sensor magnets. In some embodiments, the generating the measurement of the magnetic field includes measuring a magnetic field component created at least in part by the one or more position sensor magnets fixedly mounted to the camera lens carrier. In some embodiments, the camera lens carrier is moveably coupled to a substrate by the autofocus actuator to provide motion in a direction orthogonal to the substrate. In some embodiments, the generating the measurement of the magnetic field component includes measuring the magnetic field component at a sensor fixedly mounted to the substrate of the autofocus actuator.