Self-Oscillation Coil for Miniaturized Displacement Detection
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Solution Overview
Problem
Conventional inductive position detection devices face challenges in achieving accurate detection of small or minute displacements and miniaturization due to limited inductance variation in self-oscillation circuits, especially when using magnetism-responsive members like iron.
Innovation Solution
A displacement detection device incorporating a coil and a magnetism-responsive member within a self-oscillation circuit, where the oscillation frequency varies with inductance changes, allowing for calculation of velocity and displacement data through differential and integral operations, respectively, thereby canceling offset errors and enabling precise detection of small displacements while miniaturizing the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a self-oscillation circuit is used to eliminate the dedicated AC signal source for miniaturization, then device size is reduced, but inductance variation becomes insufficient for accurate detection of small displacements
Solution Approach 1:
The patent merges the coil's dual functions by incorporating it into the self-oscillation circuit as both the position detection element and the inductance element for oscillation. This integration eliminates the need for a separate dedicated AC signal source, enabling device miniaturization while maintaining detection capability through the unified coil structure.
Solution Approach 2:
The patent changes the operational parameters by using the coil's inductance variations within the self-oscillation circuit to generate oscillation frequency changes. By monitoring these frequency variations caused by magnetism-responsive member displacement, the system achieves accurate detection of small displacements despite the miniaturized structure.
2Device complexity
If the coil is incorporated in the self-oscillation circuit as an inductance element, then device complexity is reduced, but the amount of inductance variation becomes small making accurate detection difficult
Solution Approach 1:
The patent transforms the small inductance variation into a measurable signal by converting it into oscillation frequency changes. The self-oscillation circuit amplifies the significance of minor inductance variations through frequency modulation, allowing accurate detection despite reduced inductance change magnitude and simplified circuit structure.
Solution Approach 2:
The patent substitutes direct inductance measurement with oscillation frequency measurement. Instead of measuring small inductance changes directly, the system uses the coil's inductance variations to modulate the oscillation frequency, which can be measured more accurately with simpler circuitry, thus reducing overall device complexity while maintaining precision.
3Measurement precision
If conventional inductive position detection devices with separate oscillation circuits are used, then detection accuracy is maintained, but device size increases
Solution Approach 1:
The patent combines the oscillation circuit and position detection coil into a single integrated structure. The coil serves dual purposes as both the detection element and the inductance element of the self-oscillation circuit, eliminating the need for separate oscillation circuits and dedicated AC signal sources, thereby achieving miniaturization without sacrificing detection accuracy.
Solution Approach 2:
The patent makes the coil multi-functional by using it simultaneously for position detection and as the inductance element for oscillation generation. This universal application of the coil eliminates redundant components, reducing device size while maintaining the accuracy needed for detecting small displacements.
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 device achieves precise displacement detection with enhanced dynamic range, effectively canceling offset errors and allowing for miniaturization, even for small or minute displacements, by utilizing the self-oscillation circuit's inductance variations to generate accurate velocity and displacement data.
Implementation Method 1
a self-oscillation circuit that incorporates the coil (11) therein as an oscillation element so that an oscillation frequency varies with an inductance variation of the coil (11) responsive to the displacement of the magnetism-responsive member (12) relative to the coil (11)
Data Source
AI summary
A device has a construction capable of promoting miniaturization, and comprises: a coil; a magnetism-responsive member disposed so as to be displaced relative to the coil according to a position of a detection object; and a self-oscillation circuit that incorporates the coil therein as an oscillation element so that an oscillation frequency varies with an inductance variation of the coil responsive to an displacement of the magnetism-responsive member relative to the coil. An arithmetic section generates a measured value responsive to oscillation frequency based on an oscillation output of the self-oscillation circuit, calculates velocity data by differentiating successive measured values, and calculates displacement data by integrating the velocity data. An offset error component caused by the peripheral temperature or a mechanical attachment position of the detection device can be automatically cancelled or reduced by the differential operation for calculating the velocity data, and precise displacement detection can be realized.