TMR Magnetic Sensor for TPMS Communication
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Solution Overview
Problem
Current tire pressure monitoring systems (TPMS) face challenges in reducing the size and cost of low-frequency (LF) antenna coils and magnetic reed switches, which are essential for bi-directional communication, while also dealing with interference from magnetic impulse noise and reliability issues in harsh mechanical environments.
Innovation Solution
Integration of a magnetic sensor, such as a tunnel magneto-resistive (TMR) sensor, into the TPMS sensor integrated circuit to detect modulated low-frequency electromagnetic carrier signals and static magnetic fields, enabling both LF uplink and magnetostatic communication without the need for external LF antenna coils or magnetic reed switches, thus reducing size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a resonant LF antenna coil is used for communication, then communication sensitivity is improved, but the device size and cost increase
Solution Approach 1:
The patent replaces the mechanical resonant antenna coil system with a magnetic sensor-based detection system. Instead of using a physical coil that requires resonance and occupies significant space, the invention uses a magnetic sensor to detect magnetic field changes directly, eliminating the need for a large resonant antenna structure while maintaining communication capability.
Solution Approach 2:
The patent changes the operating principle from resonant frequency-based detection to direct magnetic field sensing. By changing the detection parameter from requiring high Q-factor resonance to direct magnetic field measurement, the system achieves comparable sensitivity without the size and cost penalties of a resonant antenna coil.
2Ease of operation
If a magnetic reed switch is used for uplink communication, then a simple permanent magnet tool is sufficient, but the device size increases and reliability decreases in harsh environments
Solution Approach 1:
The patent replaces the mechanical reed switch with a solid-state magnetic sensor. The magnetic sensor detects magnetic field changes electronically without mechanical moving parts, eliminating the reliability issues associated with mechanical switches in harsh environments while maintaining the simplicity of using a permanent magnet for actuation.
Solution Approach 2:
The magnetic sensor serves multiple functions: it can detect the permanent magnet for uplink communication initiation, sense magnetic field changes for data transmission, and potentially function as an accelerometer or compass. This multi-functionality replaces the specialized reed switch while improving reliability and reducing size.
3Duration of action of stationary object
If motion detection sensor is used to conserve battery life, then battery service life is maximized, but the sensor cannot receive downlink communication while parked
Solution Approach 1:
The patent replaces the motion-detection-based power management approach with a magnetic field-based detection system. The magnetic sensor can detect both motion (through changes in magnetic field orientation) and static magnetic fields, allowing the system to remain in low-power mode while still being able to detect and respond to downlink communication signals from external transmitters.
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 magnetic sensor solution provides a compact, cost-effective, and reliable communication method for TPMS, minimizing interference and enhancing system performance with lower current consumption and increased accuracy.
Implementation Method 1
a magnetic sensor configured to detect a modulated low-frequency electromagnetic carrier signal as a communication signal
Implementation Method 2
detecting static magnetic fields, and transmitting magnetostatic field information to the microcontroller unit
Implementation Method 3
Integration of a magnetic sensor, such as a tunnel magneto-resistive (TMR) sensor, into the TPMS sensor integrated circuit
Data Source
AI summary
A sensor device and a communication method are provided. The sensor includes a microcontroller unit, and a receiver electrically connected to the microcontroller unit and configured to receive at least one communication signal. The receiver includes a magnetic sensor configured to detect a modulated electromagnetic carrier signal as a first communication signal and output an encoded measurement signal based on the detected modulated electromagnetic carrier signal. The sensor device further includes a demodulator configured to convert the encoded measurement signal into a data signal and output the data signal to the microcontroller unit.