Contactless Angular Sensor Using Magnetic and Capacitive Coupling
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Solution Overview
Problem
Existing angular motion sensors for rotating objects, such as tachymetry generators and optical encoders, suffer from wear-related reliability degradation, complexity, and sensitivity to temperature and vibration, leading to reduced precision and increased costs.
Innovation Solution
A contactless angular motion sensor utilizing a frame with a fixed and rotating part, featuring magnetic and capacitive couplings between printed circuits with conductive pads, eliminating direct contact and minimizing temperature-induced drift, and simplifying the structure for easier manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contactless coupling is used between fixed and moving parts, then reliability is improved due to reduced wear, but device complexity increases due to magnetic and capacitive coupling structures
Solution Approach 1:
The sensor is divided into a fixed part and a moving part that are spatially separated but functionally connected through magnetic and capacitive couplings. This segmentation eliminates direct mechanical contact while maintaining functional integrity, resolving the contradiction between reliability and complexity.
Solution Approach 2:
Magnetic fields and electric fields serve as intermediary carriers to transmit signals between the fixed and moving parts without direct contact. The magnetic coupling transfers excitation signals, while capacitive coupling transfers measurement signals, enabling contactless communication and improving reliability.
2Measurement precision
If magnetic and capacitive couplings are used for signal transmission, then measurement precision is improved with large amplitude signals, but energy consumption increases
Solution Approach 1:
The patent combines magnetic coupling for excitation signal transmission and capacitive coupling for measurement signal transmission within a single sensor structure. This merged approach achieves high measurement precision through large amplitude signals while optimizing energy consumption by utilizing the complementary strengths of both coupling mechanisms.
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 sensor achieves long-lasting reliability with reduced wear and sensitivity to environmental factors, providing large amplitude measurement signals for easier processing and cost-effective production.
Implementation Method 1
a primary excitation winding (15) in the form of a flat coil extending around the periphery of the first part (1)... The windings and the conductive pads are centered on the axis of rotation of the second part (2) and arranged to respectively create magnetic and capacitive couplings between the first printed circuit (10) and the second printed circuit (20)
Implementation Method 2
two conductive pads (11, 12) which have an elongated shape extending radially with respect to the axis of rotation (X)... The first printed circuit (10) and the second printed circuit (20) respectively comprise conductive pads to form capacitive sectors
Implementation Method 3
a secondary excitation winding (25) in the form of a flat coil which extends around the periphery of the second part (2)... The first printed circuit (10) and the second printed circuit (20) arranged to respectively create magnetic and capacitive couplings between the first printed circuit (10) and the second printed circuit (20)
Data Source
Figure 1~3
Figure 4
AI summary
A sensor for sensing the angular motion of an object, comprising a frame (0) on which a first stationary part (1) and a second rotatably movable part (2) are mounted, bearing, respectively, a first printed circuit (10) and a second printed circuit (20) centred on the axis of rotation (X) and facing each other, that comprise conductive pads (11, 12, 21, 22) for forming capacitive sectors and, respectively, a primary excitation winding (15) and a secondary excitation winding (25) connected to the conductive pads (21, 22) of the second printed circuit; the first printed circuit being connected to an electronic control circuit (30) arranged to create excitation signals transmitted by the first printed circuit to the second printed circuit by magnetic coupling and demodulate signals transmitted by the second printed circuit to the first printed circuit by capacitive coupling.