Magnetic Swing Actuator Angle Detection for Compact Optical Scanners
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Solution Overview
Problem
Conventional bearing-type optical scanning devices face challenges in miniaturization and accuracy due to the limitations of photodiodes and LEDs, particularly in environments with significant temperature fluctuations, where the accuracy of angle detection is compromised.
Innovation Solution
The design incorporates a swing portion that is electrically conductive and swingable about two orthogonal axes, supported by a frame and drive assembly with a magnet and non-magnetic structure, utilizing a pair of angle detection elements with columnar magnetic structures and detection coils to accurately detect the swing angle, independent of temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photodiodes and LEDs are used for angle detection, then angle detection can be implemented, but the device cannot be miniaturized and temperature range is limited
Solution Approach 1:
The patent replaces the optical detection system (photodiodes and LEDs) with a magnetic field-based detection system using detection coils and magnets. This substitution enables angle detection through magnetic field interactions rather than optical methods, allowing for significant miniaturization of the device while maintaining detection functionality
Solution Approach 2:
The patent changes the detection parameter from optical properties (light emission and detection) to magnetic properties (magnetic field strength and direction). By using magnets attached to the swing portion and detection coils in the stationary part, the system detects angle changes through variations in magnetic field parameters, enabling operation across a wide temperature range and reducing device size
2Measurement precision
If photodiodes and LEDs are used for angle detection, then angle detection can be implemented, but accuracy is compromised in high or low temperature environments
Solution Approach 1:
The patent replaces temperature-sensitive optical components (photodiodes and LEDs) with magnet-based detection components that are insensitive to temperature variations. Magnets and detection coils maintain their magnetic properties across a wide temperature range, enabling accurate angle detection in both high and low temperature environments
Solution Approach 2:
The patent changes the detection mechanism from optical parameters (which are temperature-dependent) to magnetic parameters (which are temperature-independent). The magnetic field strength and direction detected by the coils remain stable across temperature changes, ensuring consistent angle detection accuracy regardless of environmental temperature
3Measurement precision
If photodiodes and LEDs are arranged on the back surface of the mirror, then angle detection is possible, but the device structure becomes complex and difficult to miniaturize
Solution Approach 1:
The patent replaces the complex optical component arrangement (photodiodes and LEDs mounted on the mirror back surface with light reflection paths) with a simpler magnetic field-based system. Magnets are attached to the swing portion and detection coils are placed in the stationary housing, eliminating the need for complex optical alignment and reducing structural complexity
Solution Approach 2:
The patent merges the detection function into the stationary housing structure by placing detection coils within the housing rather than requiring separate optical components on the moving mirror. This integration simplifies the overall device structure, reduces the number of components, and facilitates miniaturization
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 configuration enables precise angle detection and miniaturization of the optical scanning device, maintaining accuracy across varying temperatures and improving resolution in detecting the position and shape of objects, especially at distances.
Implementation Method 1
a detection coil extending along an outer periphery of the magnetic structure
Data Source
AI summary
An actuator includes a swing portion swingable about a first axis orthogonal to a central axis extending vertically and about a second axis orthogonal to the first axis and intersecting the central axis. An angle detector includes a pair of first angle detection elements above a non-magnetic structure and extending in the second axis direction with the first axis interposed therebetween when viewed from the central axis direction, and a pair of second angle detection elements extending in the first axis direction with the second axis interposed therebetween. Each of the first angle detection elements and each of the second angle detection elements include a columnar magnetic structure between the swing portion and the non-magnetic structure in the central axis direction, and a detection coil along the outer periphery of the magnetic structure.