Rotation Angle Measuring Apparatus Using Magnetic and Capacitive Sensors
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Solution Overview
Problem
Existing rotation angle measuring apparatuses, particularly capacitive rotary encoders, face challenges in determining absolute rotation angles with high precision and robustness, especially when measuring multiple circles, due to complexity and cost constraints.
Innovation Solution
A rotation angle measuring apparatus and method that incorporates a moving disk with a magnet and periodically varying reflecting regions, a stationary disk with emitting and receiving regions forming a static electric field, and magnetic sensors to generate angle signals, allowing for incremental and absolute rotation angle determination with improved precision and robustness, including multiple-circle measurement capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitive rotary encoder is used to determine absolute rotation angles, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The encoder is divided into two functional parts: a capacitive measurement system for high-precision incremental angle detection and a magnetic detection system for determining the period and number of circles. This segmentation allows each subsystem to be optimized independently, reducing overall complexity while maintaining measurement precision.
Solution Approach 2:
The magnetic sensor serves multiple functions: detecting the period of the static electric field and determining the number of circles rotated. By making this component multi-functional, the patent reduces the need for additional specialized components, thereby simplifying the overall device structure.
2Measurement precision
If magnetic sensors with high sensitivity requirements are used, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent changes the operating parameters of the magnetic sensor to achieve optimal sensitivity with reduced power consumption. By adjusting detection thresholds and signal processing parameters, the system maintains measurement precision while lowering energy requirements.
Solution Approach 2:
The magnetic sensor operates in a periodic measurement mode, taking readings at specific intervals rather than continuously. This periodic operation significantly reduces power consumption while still capturing all necessary information about the period and number of circles.
3Device complexity
If incremental rotation angle measurement is used, then device complexity is reduced, but measurement capability is limited to single circle
Solution Approach 1:
The magnetic sensor acts as an intermediary that bridges the incremental capacitive measurement system with the absolute position information. By detecting the period and number of circles, it enables the system to determine absolute rotation angles across multiple circles while keeping the capacitive measurement subsystem relatively simple.
Solution Approach 2:
The patent merges incremental measurement (from capacitive sensors) with absolute position detection (from magnetic sensors) into a unified measurement system. This combination allows the system to achieve both the simplicity of incremental encoding and the multi-circle capability of absolute encoding.
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 provides a simple, compact, and cost-effective apparatus capable of determining absolute rotation angles with high precision and robustness, while reducing the sensitivity requirements of magnetic sensors and power consumption, enabling accurate multiple-circle measurements.
Implementation Method 1
a magnet, arranged on the moving disk; a first magnetic sensor, arranged on the stationary disk, and generating an angle signal under the action of the magnet
Implementation Method 2
a receiving region, being able to form a static electric field with the emitting region, the static electric field being modulated by the reflecting region and hence periodically varying as the moving disk rotates
Data Source
AI summary
A rotation angle measuring apparatus and method are provided for measuring a rotation angle of a moving disk relative to a stationary disk, the moving disk being configured to rotate about an axis and the stationary disk being arranged opposite the moving disk. A magnet is arranged on the moving disk. A first magnetic sensor is arranged on the stationary disk, the first magnetic sensor generating an angle signal under the action of the magnet as the moving disk rotates. An incremental rotation angle of the moving disk is determined on the basis of an output of the receiving region, a period of the static electric field is determined on the basis of an angle signal generated by the first magnetic sensor, and an absolute rotation angle of the moving disk is determined on the basis of the period of the static electric field and the incremental rotation angle.