Magnetic Field Rotation Angle Detection Circuit
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Solution Overview
Problem
Existing magnetic field rotation angle detection devices require a four-pole auxiliary magnet and A/D conversion circuits, increasing component mounting area and current consumption, making it costly and inefficient to achieve high resolution without these components.
Innovation Solution
A detection circuit with two sensor units of bridge-connected magnetoresistance elements arranged at a predetermined angle, using comparison and amplification circuits to calculate rotation angles with higher resolution without the need for a four-pole auxiliary magnet or A/D conversion circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a four-pole auxiliary magnet is used to generate a synthesized rotating magnetic field, then the rotation angle detection range is improved to 0°-360°, but the component mounting area and device complexity significantly increase
Solution Approach 1:
The patent removes the four-pole auxiliary magnet from the system entirely. Instead of using multiple magnets to generate a synthesized magnetic field, the invention uses a single rotating magnet combined with a magnetic sensor that has two sensor units arranged at specific angles, eliminating the need for the auxiliary magnet and reducing mounting area
Solution Approach 2:
The patent replaces the mechanical approach of using multiple magnets (four-pole auxiliary magnet + rotating magnet) with a magnetic field detection approach using sensor units positioned at specific orientations. The sensor units detect magnetic field components along different axes, and the control circuit calculates the rotation angle from these signals, substituting physical magnetic field synthesis with electronic signal processing
2Measurement precision
If an A/D conversion circuit is used for signal processing, then high resolution rotation angle detection is achieved, but the current consumption and cost significantly increase
Solution Approach 1:
The patent replaces the A/D conversion circuit with a control circuit that performs analog signal processing. The control circuit directly processes the analog signals from the magnetic sensor, compares them against reference signals, and determines the rotation angle through analog comparison and logic operations, eliminating the need for analog-to-digital conversion and reducing power consumption
Solution Approach 2:
The patent changes the processing approach from digital conversion to analog signal manipulation. By using operational amplifiers, comparators, and logic circuits that operate directly on analog signals, the system maintains high resolution detection capability while avoiding the high current consumption associated with A/D conversion circuits
3Device complexity
If two sensor units are arranged at 45° to each other, then the circuit configuration is simplified, but the rotation angle detection resolution is limited to 45° (1/8 rotation)
Solution Approach 1:
The patent enhances the detection capability by adding signal processing dimensions through operational amplifiers and comparators. Instead of relying solely on the geometric arrangement of sensor units, the invention uses multiple comparison operations and logic circuitry to extract finer angular information from the sensor outputs, effectively increasing resolution without changing the physical sensor arrangement
Solution Approach 2:
The control circuit uses feedback mechanisms through comparators that compare sensor outputs with reference signals. By continuously comparing the magnetic field signals against reference values and using logic circuits to determine angular quadrants and positions, the system achieves resolution finer than the physical sensor spacing would suggest
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
Enables detection of magnetic field rotation angles with resolutions finer than 45°, reducing circuit size and cost by eliminating the need for A/D conversion circuits and achieving high-resolution angle detection in electronic devices like water and gas meters.
Implementation Method 1
MR elements have the property to change the value of their resistance depending on the intensity of a magnetic field because of the magnetoresistance effect
Data Source
AI summary
Detection of the rotation angle of a magnetic field using a magnetic sensor in which two sensor units are arranged at a predetermined angle with respect to each other is performed with a resolution of an angle smaller than 45° with a simple circuit configuration. A detection circuit is connectable to a magnetic sensor in which first and second sensor units are arranged at a predetermined angle with respect to each other, each sensor unit having a bridge circuit of magnetoresistance elements. The detection circuit includes a first comparison circuit that compares output signals of the first or second sensor unit, a second comparison circuit that compares an output signal of the first sensor unit with an output signal of second sensor unit, and a rotation angle calculation circuit that calculates a rotation angle of a magnetic field based on the comparison results of the first and second comparison circuits.