Magnetic Sensor Bridge Circuit Shunt Current Reduction
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Solution Overview
Problem
Magnetic sensors with bridge circuits and magnetoresistance effect elements face errors in detecting the rotation angle of a rotator due to shunt current flowing into external devices, causing electrical unbalance and inaccuracies in output voltage measurement.
Innovation Solution
A magnetic sensor design with a bridge circuit comprising four resistance element sections, each including at least one magnetoresistance effect element, and two resistors connected to output terminals, where the resistance ratio of each resistor to the bridge circuit is at least 2, effectively reducing shunt current and improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the output voltage from the bridge circuit is measured directly by connecting to an external device, then the measurement process is simple, but shunt current flows into the external device causing electrical unbalance and measurement error
Solution Approach 1:
High-value resistors are introduced as intermediary elements connected between the bridge circuit output terminals and the external measurement device. These resistors act as mediators that limit the shunt current flowing to the external device, thereby preventing electrical unbalance in the bridge circuit while still allowing the output voltage to be measured. The resistors are positioned strategically to block harmful current paths without interfering with the voltage signal.
Solution Approach 2:
The invention changes the electrical parameters of the measurement system by introducing resistors with specifically high resistance values (at least 2 times the minimum resistance of the bridge circuit). This parameter change effectively reduces the shunt current to acceptable levels. By adjusting the resistance parameter, the system achieves a balance between maintaining bridge circuit stability and enabling external voltage measurement.
2Power
If the resistance of resistors connected to the bridge circuit output terminals is low, then the voltage signal is strong, but shunt current increases causing electrical unbalance
Solution Approach 1:
The invention optimizes the resistance parameter of the resistors connected to the bridge circuit output terminals. By setting the resistance to be at least 2 times the minimum resistance of the bridge circuit, the system achieves an optimal balance: the resistance is high enough to limit shunt current and maintain bridge circuit electrical balance, yet low enough to maintain adequate voltage signal strength for accurate measurement.
Solution Approach 2:
The resistors are placed specifically at the output terminals of the bridge circuit, applying the quality change locally at the critical interface between the bridge circuit and external measurement devices. This localized application of high resistance precisely where needed allows the rest of the bridge circuit to maintain its normal low-resistance, high-signal operation.
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 significantly reduces angle errors caused by shunt current, enhancing the accuracy of magnetic field detection and maintaining accuracy across various temperatures, with an optimal resistance ratio of at least 2 to 12 times the minimum resistance of the bridge circuit.
Implementation Method 1
a bridge circuit configured to provide an output that changes in accordance with the direction of an external magnetic field, the bridge circuit including four resistance element sections, each of which includes at least one magnetoresistance effect element
Data Source
AI summary
A magnetic sensor for detecting a direction of an external magnetic field comprises: a bridge circuit configured to provide an output that changes in accordance with the direction of the external magnetic field, the bridge circuit including four resistance element sections, each of which comprises at least one magnetoresistance effect element; and two resistors connected to respective output terminals of the bridge circuit. The ratio of the resistance of each of the resistors to that of the bridge circuit is at least 2 when the resistance of each of the resistance element sections is at a minimum corresponding to a change in magnetoresistance.