Position Detection Unit Asymmetric Sensor Placement
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Solution Overview
Problem
Position detection units using magnetic sensors face challenges in achieving high detection accuracy due to limitations in accurately detecting positional changes of moving components, such as lenses, in imaging apparatuses.
Innovation Solution
A position detection unit, lens module, and imaging apparatus that incorporate a magnetic sensor, a first magnetic field generator with two spaced magnets, and a second magnetic field generator movable orthogonal to the first, allowing the magnetic sensor to detect positional changes of the second magnetic field generator by sensing a composite magnetic field, which improves detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic sensor is used to detect lens position, then detection capability is provided, but detection accuracy is insufficient
Solution Approach 1:
The magnetic field detection is segmented into two independent components: a first magnetic field generator (with first and second magnets) providing a reference magnetic field, and a second magnetic field generator (movable magnet) providing position-dependent magnetic field variations. The magnetic sensor detects the composite field, and the controller separates and processes these components independently to determine lens position, thereby improving detection accuracy while maintaining reliability.
Solution Approach 2:
A third magnetic field generator (mediator) is introduced between the first and second magnetic field generators. This intermediary element helps to stabilize the magnetic field distribution and provides a reference that enhances the sensor's ability to distinguish positional changes, thereby improving both detection accuracy and reliability simultaneously.
2Measurement precision
If a single magnetic field generator is used, then device complexity is low, but detection accuracy is insufficient
Solution Approach 1:
The magnetic field generation function is segmented into multiple independent generators: a first magnetic field generator with fixed magnets providing a reference field, and a second magnetic field generator with a movable magnet providing position-dependent field variations. This segmentation enables accurate position detection through composite field analysis while keeping each individual generator relatively simple in structure.
Solution Approach 2:
The first magnetic field generator serves multiple functions: it provides a reference magnetic field for the sensor, establishes a baseline field distribution, and enables the sensor to detect variations caused by the second generator's movement. This multi-functionality improves detection accuracy without proportionally increasing overall device complexity.
3Measurement precision
If the magnetic sensor is positioned at the midpoint between magnets, then field symmetry is achieved, but detection accuracy deteriorates
Solution Approach 1:
The magnetic sensor is deliberately positioned asymmetrically relative to the first and second magnets, specifically at a location where the magnetic field gradient provides maximum sensitivity to the movement of the second magnet. This asymmetric positioning creates an optimal detection point where small positional changes produce measurable field variations, thereby improving detection accuracy while maintaining controlled field composition through the multi-generator approach.
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 enhances detection accuracy by allowing the magnetic sensor to effectively track positional changes of the second magnetic field generator, thereby improving the precision of lens positioning in imaging apparatuses, reducing measurement errors, and maintaining accuracy across varying temperatures.
Implementation Method 1
the magnetic sensor is configured to generate a detection signal corresponding to a direction of a detection-target magnetic field, and configured to detect a positional change of the second magnetic field generator. The detection-target magnetic field is a magnetic field to be detected, and is a composite of the first magnetic field along a plane orthogonal to the second direction and the second magnetic field along the plane.
Data Source
AI summary
A position detection unit includes a magnetic sensor, a first magnetic field generator, and a second magnetic field generator. The first magnetic field generator includes a first magnet and a second magnet spaced apart from each other in a first direction, and generates a first magnetic field. The second magnetic field generator generates a second magnetic field and is movable along a second direction orthogonal to the first direction with respect to the first magnetic field generator and the magnetic sensor. In the first direction, a center position of the magnetic sensor lies at a position in a region between the first magnet and the second magnet other than a midpoint position between the first magnet and the second magnet. The magnetic sensor generates a detection signal corresponding to a direction of a magnetic field to be detected, and detects a positional change of the second magnetic field generator.