Position Sensor Bias Field Offset Compensation
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Solution Overview
Problem
Position sensors in small form factor cameras face challenges in accurately determining the position of optical lenses due to bias field offsets, which can lead to incomplete external field rejection and compromised image stabilization and autofocus performance.
Innovation Solution
A position sensor configuration that includes magnetic field sensors and compensation magnets to counteract bias field offsets, ensuring accurate position sensing and improved image stabilization and autofocus by generating asymmetric magnetic fields that compensate for bias field components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic field sensors are used for position sensing in small form factor cameras, then position detection capability is provided, but bias field offsets cause measurement inaccuracies
Solution Approach 1:
The patent introduces compensation magnets as intermediary elements that generate a counter-bias magnetic field to neutralize the harmful bias field offset. These compensation magnets are positioned between the asymmetric magnet arrangement and the magnetic field sensors, acting as a mediator to cancel out the unwanted bias field and enable accurate position measurement.
Solution Approach 2:
The compensation magnets are pre-configured to generate a magnetic field that anticipates and counteracts the bias field offset before it affects the position sensing. By placing the compensation magnets in specific positions and orientations, the system proactively neutralizes the harmful bias field effect, preventing measurement errors rather than correcting them afterward.
2Adaptability or versatility
If asymmetric magnet arrangement is used for VCM actuation, then actuation functionality is provided, but bias field components are generated that offset from orthogonal axes
Solution Approach 1:
The patent converts the harmful bias field component generated by the asymmetric magnet arrangement into a useful element by using compensation magnets to create a counter-bias field. The compensation magnets transform the problematic offset field into a controlled counteracting field that enables both actuation functionality and accurate position sensing simultaneously.
Solution Approach 2:
The patent employs an asymmetric magnet arrangement for VCM actuation that intentionally creates a non-uniform magnetic field. This asymmetric configuration is complemented by strategically placed compensation magnets that generate a counter-asymmetric field to balance the overall magnetic environment, allowing the system to maintain actuation versatility while eliminating harmful bias effects.
3Measurement precision
If compensation magnets are added to counteract bias field offsets, then position sensing accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges the compensation magnets with the existing asymmetric magnet arrangement by integrating them into the same structural framework. The compensation magnets are positioned in close proximity to the asymmetric magnets and share common mounting structures, reducing the overall device complexity despite adding functional elements.
Solution Approach 2:
The compensation magnets serve multiple functions: they counteract bias field offsets for accurate position sensing, maintain the magnetic field structure for VCM actuation, and can be integrated with existing camera module components. This multi-functionality reduces the need for separate compensation mechanisms, thereby limiting the increase in device complexity.
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 effectively compensates for bias field offsets, enhancing the accuracy of position sensing and resulting in improved image stabilization and autofocus performance in small form factor cameras.
Implementation Method 1
The first magnetic field sensor may be configured to detect one or more magnetic field components to enable determination of a position, along the optical axis, of the optical package. The magnetic field components may include at least one magnetic field component produced by the first position sensor magnet.
Implementation Method 2
The first set of compensation magnets may be configured to contribute to one or more compensation magnetic fields. In various embodiments, the compensation magnetic fields counteract a first bias field component that is offset relative to a first axis that is orthogonal to the optical axis.
Data Source
AI summary
Various embodiments include a position sensor configuration that compensates for a bias field offset. The position sensor configuration may be used for position sensing of components, such as camera components, that are movable via an actuator (e.g., a voice coil motor actuator). In some embodiments, the actuator may include an asymmetric magnet arrangement that produces an asymmetric magnetic field. The asymmetric magnetic field may include one or more bias field components that are offset relative to one or more axes. In some examples, the position sensor configuration may include one or more magnetic field sensor packages. Individual ones of the magnetic field sensor packages may include a magnetic field sensor and one or more compensation magnets. The compensation magnets may be configured to contribute to one or more compensation magnetic fields that counteract the bias field components such that the compensation magnetic fields compensate for the bias field offset.