Magnetic Encoder Adjusting Offset to Maintain Signal Accuracy
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Solution Overview
Problem
Magnetic encoders with large magnetic pole pitches face errors in detection values due to the difficulty in changing the offset between magnetoresistive element groups, leading to reduced magnetic field strength and detection signal quality when used with magnetic field generators having different pole pitches.
Innovation Solution
A magnetic encoder design with a magnetic field generator and sensor configuration that includes pairs of N and S poles alternately arranged, where the sensor generates detection signals with resistors arranged to reduce harmonic components, particularly the second-order harmonic, allowing for a magnetic pole pitch greater than the design pitch while maintaining signal accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the distance between the magnetic sensor and the magnetic field generator is increased to prevent collision in devices with great vibration, then the reliability of the device is improved, but the magnetic field strength applied to the magnetic sensor decreases and the detection signal is reduced
Solution Approach 1:
The patent changes the magnetic pole pitch parameter of the magnetic field generator from a small value to a great value. This parameter change allows the magnetic field generator to maintain sufficient magnetic field strength at larger distances from the sensor, thereby preventing collision while preserving detection signal quality
2Reliability
If the magnetic pole pitch of the magnetic field generator is increased to maintain magnetic field strength at large distances, then the reliability is improved, but the offset amount between magnetoresistive element groups cannot be easily changed leading to detection errors
Solution Approach 1:
The patent makes the offset amount between the first and second magnetoresistive element groups adjustable rather than fixed. This dynamic adjustment capability allows the offset to be optimized for different magnetic pole pitch values, thereby maintaining detection accuracy even when using a magnetic field generator with a great magnetic pole pitch
Solution Approach 2:
The patent changes the offset amount parameter between magnetoresistive element groups to match the great magnetic pole pitch of the magnetic field generator. This parameter adjustment ensures that the detection signals maintain the appropriate phase relationship, preventing detection errors while using a large pole pitch configuration
3Device complexity
If the pitch between magnetoresistive elements is maintained while using a magnetic field generator with great magnetic pole pitch, then the device complexity is reduced, but the detection value error increases
Solution Approach 1:
The patent introduces adjustability in the offset amount between magnetoresistive element groups, allowing the system to adapt to different magnetic pole pitch configurations without requiring complete redesign of the element arrangement, thus balancing complexity and precision
Solution Approach 2:
The patent adjusts the offset parameter between magnetoresistive elements to correspond with the great magnetic pole pitch, maintaining detection accuracy through parameter optimization rather than through complex structural changes
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 configuration reduces errors associated with differences in magnetic pole pitch, ensuring accurate detection signals even with increased magnetic pole pitches, enhancing the encoder's performance in devices with vibrations.
Implementation Method 1
a magnetic field generator configured to generate a target magnetic field including a magnetic field component in a first direction
Implementation Method 2
a magnetic sensor configured to detect the target magnetic field
Implementation Method 3
a plurality of resistors each configured to change in resistance with change in the strength of the magnetic field component
Data Source
AI summary
A magnetic encoder includes a magnetic field generator configured to generate a target magnetic field including a magnetic field component, and a magnetic sensor configured to detect the target magnetic field. The magnetic sensor includes a plurality of resistors each configured to change in resistance with change in strength of the magnetic field component. The magnetic field generator is a magnetic scale including a plurality of pairs of N and S poles alternately arranged. A magnetic pole pitch being a center-to-center distance between two N poles adjoining via one S pole is different from a design pitch being four times a distance between a predetermined position in one resistor included in the plurality of resistors and a predetermined position in another resistor.