Magnetic Field Sensor Single Coil Calibration and Reset
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing magnetic field sensors face challenges such as excessive size, inadequate sensitivity, temperature dependence, hysteresis, and complexity due to the need for multiple coils for calibration and reset operations, which complicates manufacturing and increases size, while sensors without calibration coils cannot measure sensitivity electrically.
Innovation Solution
A magnetic field sensor design utilizing magnetoresistive elements with a single on-chip coil for both calibration and reset operations, employing a low unipolar or bipolar current pulse cycle for calibration and a large unipolar current for reset, with a coil configuration that generates magnetic fields parallel and perpendicular to the sensing axis to align domains and calibrate the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple coils (calibration coil and set/reset coil) are used, then calibration and reset functions are achieved, but device complexity and size increase
Solution Approach 1:
The patent combines the calibration coil and set/reset coil into a single integrated coil structure. The coil is configured with multiple turns where different segments carry current in opposite directions, enabling both calibration (producing magnetic field parallel to sensing axis) and reset (producing magnetic field perpendicular to sensing axis) functions through controlled current direction, thereby reducing the number of separate coils from two to one.
Solution Approach 2:
The single coil is designed to perform multiple functions: it serves as both the calibration coil and the set/reset coil. By controlling the direction of current flow through different segments of the same coil, the system achieves both calibration and reset operations without requiring separate dedicated coils, thus implementing multi-functionality in a single component.
2Reliability
If multiple coils are used, then calibration and reset operations are enabled, but manufacturing process complexity increases
Solution Approach 1:
The patent integrates multiple coil functions into a single coil structure that can be fabricated as one continuous conductive element. This single coil is patterned with multiple turns and segments that can be manufactured in a single fabrication process step, eliminating the need to separately fabricate and align multiple independent coils, thereby simplifying the manufacturing process while maintaining calibration and reset capabilities.
3Use of energy by moving object
If distance between sensor and calibration coil is reduced, then power consumption decreases, but physical space constraints are violated
Solution Approach 1:
The patent places the calibration function and set/reset function within the same coil structure that is already positioned near the magnetoresistive sensor elements. By integrating both functions into a single coil located in close proximity to the sensor, the design achieves low power consumption for calibration operations without requiring additional space for separate coils, as the same physical structure serves both purposes.
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 design simplifies the manufacturing process, reduces sensor size, and allows for high-accuracy sensitivity measurement and calibration, achieving improved sensitivity and temperature compensation while minimizing hysteresis and complexity.
Implementation Method 1
a coil placed near said magnetoresistive sensing elements, which generates a magnetic field parallel to the sensing axis of said magnetoresistive elements
Implementation Method 2
magnetoresistive sensing elements
Implementation Method 3
a first current through the coil is used to reset the sensing elements while a second current is used to calibrate the response of the sensing elements
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention discloses a magnetic field sensing device that utilizes a single coil for calibrating the response of the sensor to compensate for temperature dependent sensitivity drift and also for resetting the magnetic field sensor in order to eliminate hysteresis. The single coil configuration is advantageous since it reduces the size of the sensor chip by decreasing the number of contact pads on the chip and also because it wastes less space, which permits an increase in the density of the magnetoresistive elements on the sensor chip.