Magnetic Detection Device Bridge Circuit Topology
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Solution Overview
Problem
Existing magnetic detection devices used in high-resolution magnetic encoders have complex and large circuit structures, which hinder achieving both small circuit size and high detection accuracy.
Innovation Solution
A magnetic detection device with a bridge circuit that includes resistive units connected between output portions of series circuits, allowing for the generation of pulse signals with high accuracy without the need for a differential amplifier, and using magnetic detection elements whose resistance values change in response to external magnetic fields to shift reference voltages and create potential differences for comparators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a differential amplifier and Schmitt trigger comparators are used to achieve high detection accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the differential amplifier from the circuit, using only two comparators to directly process the bridge circuit output. This removal of the differential amplifier stage simplifies the circuit structure while maintaining detection accuracy through direct comparator evaluation of the bridge output voltages.
Solution Approach 2:
The comparators in the patent perform multiple functions: they directly compare the bridge circuit output voltages against reference voltages and generate the final detection signals without requiring separate differential amplification. This multi-functional approach reduces the number of circuit components needed.
2Measurement precision
If a differential amplifier and multiple comparators are used to achieve high detection accuracy, then measurement precision is improved, but the size of the circuit structure increases
Solution Approach 1:
The patent removes the differential amplifier component entirely, reducing the physical footprint of the circuit. By using comparators that directly evaluate the bridge circuit outputs against reference voltages, the circuit occupies less area while achieving the same detection accuracy.
Solution Approach 2:
The patent combines the functions of differential amplification and signal comparison into a single comparator stage. The comparators directly process the bridge circuit outputs without requiring separate amplification hardware, thereby reducing the overall circuit size.
3Device complexity
If resistive units are connected between output portions of series circuits, then device complexity is reduced, but measurement precision may be compromised
Solution Approach 1:
The patent introduces resistive units as intermediary elements connected between the output portions of the series circuits and the comparators. These resistive units serve as mediators that enable direct comparator evaluation while maintaining signal integrity and detection accuracy, eliminating the need for complex differential amplification.
Solution Approach 2:
The patent changes the circuit configuration by introducing resistive units that modify the voltage distribution at the comparator inputs. This parameter change allows the comparators to directly evaluate the bridge circuit outputs with appropriate reference voltages, achieving both simplification and maintained precision.
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
This configuration results in a small circuit structure with high detection accuracy and improved operation stability, enabling the generation of pulse signals with high precision and simplifying the circuit design compared to previous technologies.
Implementation Method 1
a plurality of magnetic detection elements R11 to R22 whose magnetic characteristics are changed by an external magnetic field
Data Source
Figure 1~2
Figure 3A~3B
Figure 4
AI summary
An object of the invention is to provide a magnetic detection device capable of achieving a small circuit structure and high detection accuracy, as compared to the related art. An embodiment of the invention provides a bridge circuit including magnetic detection elements whose magnetic characteristics are changed by an external magnetic field. Two output portions are provided at an intermediate point of each series circuit of the bridge circuit. A resistive unit 25 is connected between a first output portion a1 which is provided on the side of an input terminal Vdd of one series circuit and a second output portion a2 which is provided on the side of a ground terminal GND of the one series circuit and a resistive unit 26 is connected between a third output portion 3a which is provided on the side of the input terminal Vdd of the other series circuit and a fourth output portion a4 which is provided on the side of the ground terminal GND of the other series circuit. The first output portion and the fourth output portion are connected to a first comparator 30, and the second output portion and the third output portion are connected to a second comparator 31.