Self-Oscillation Position Detection Device Amplitude Analysis
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Solution Overview
Problem
Conventional self-oscillation type proximity sensors require a frequency discrimination circuit and are not capable of detecting object position based on amplitude levels of oscillation output signals, and devices using flat coils on printed circuit boards face challenges in achieving sufficient magnetic flux for detection due to limited winding turns.
Innovation Solution
A position detection device incorporating a flat coil in a self-oscillation circuit with a multi-layer structure and a magnetism-responsive member that varies inductance in response to object position, allowing for position detection based on amplitude levels of oscillation output signals without a dedicated AC signal source, and employing temperature compensation to enhance accuracy.
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, then device size is reduced, but the device requires a frequency discrimination circuit and cannot detect position based on amplitude levels
Solution Approach 1:
The patent changes the detection parameter from frequency variation to amplitude level variation. By detecting the amplitude level of the oscillation output signal, the system eliminates the need for frequency discrimination circuits while maintaining position detection capability, thus reducing device complexity without sacrificing detection functionality
Solution Approach 2:
The patent uses a flat coil structure that copies the functionality of traditional coils while adapting to printed circuit board fabrication. This allows integration of the coil directly into the PCB as part of the self-oscillation circuit, eliminating separate AC signal sources and reducing overall device size
2Device complexity
If a flat coil is used on a printed circuit board to reduce device size, then device construction is simplified, but the number of winding turns is insufficient to generate adequate magnetic flux for detection
Solution Approach 1:
The patent transitions from a traditional three-dimensional wound coil to a two-dimensional flat coil pattern on the PCB. This dimensional change allows the coil to be integrated into the printed circuit board structure, simplifying device construction and reducing size while maintaining adequate magnetic flux generation through optimized trace routing and layer configuration
Solution Approach 2:
The patent employs a magnetism-responsive member that dynamically responds to changes in magnetic flux. This member varies the inductance of the flat coil in response to the position of the detection object, enabling reliable position detection despite the reduced magnetic flux generation capability of the flat coil structure
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 simplifies the device construction, reduces size, and effectively detects object position through amplitude levels of oscillation output signals, while temperature compensation ensures accurate detection by eliminating errors due to temperature variations.
Implementation Method 1
a coil section (4), which is one of position detection elements, is incorporated in a self-oscillation circuit (10) as a variable inductance element, and this coil section is energized by self oscillation
Implementation Method 2
a target section (3) whose relative position to the coil section (4) varies in response to a position of a detection object, and which includes a magnetism-responsive member constructed to cause an inductance of the coil section (4) to vary in accordance with the relative position
Data Source
Figure 1~3
Figure 4~6
Figure 7~8
AI summary
The position detection device comprises a coil section (4); a target section (3) which includes a magnetism-responsive member constructed to cause the inductance of a coil included in said coil section (4) to vary in accordance with a position relative to the position of a detection object; a self-oscillation circuit (10) comprising the coil of the coil section (4) and a capacitor (14, 15); and an output circuit (21, 22, 23) adapted to output position data of the detection object based on an oscillation output signal of the self-oscillation circuit (10).The coil section (4) includes a plurality of coils (4a, 4b'; 41, 43', 42, 44'; 41, 42) at a predetermined interval from each other. The self-oscillation circuit (10) constructs an inductance element for self-oscillation by connecting a plurality of the voltage-dividing circuits in parallel with each other, the coil (4a, 4b'; 41, 43', 42, 44'; 41, 42) being incorporated therein. A plurality of the oscillation output signals (+DVout, - DVout; +sinOUT, -sinOUT, +cosOUT, -cosOUT) are output from the voltage-dividing points of individual ones of the voltage-dividing circuits.