Integrated Coil and GMR Sensor for Ferromagnetic Target Detection

The patent combines a coil and a magnetic field sensing element into a single integrated sensor device. The coil is positioned adjacent to the sensing element, allowing the coil to generate a magnetic field that interacts with ferromagnetic targets while the sensing element detects the resulting field changes. This integration resolves the contradiction by merging multiple functions (magnetic field generation and detection) into one device, improving measurement precision without proportionally increasing device complexity.

The integrated sensor serves multiple functions: the coil generates a magnetic field for interaction with ferromagnetic targets, while the magnetic field sensing element detects the resulting field changes. This multi-functionality improves measurement precision by incorporating both field generation and detection capabilities, while the shared physical structure helps manage overall device complexity.

The patent integrates the coil and GMR sensing element into a single device structure, improving accuracy by ensuring precise spatial relationship between the field-generating coil and the detecting element. The shared substrate and compact arrangement facilitate manufacturing by reducing alignment complexities compared to separate components, thus mitigating the worsening of ease of manufacture.

The patent employs a GMR (giant magnetoresistance) sensing element, which utilizes a specific material property that exhibits large resistance changes in response to small magnetic field variations. This parameter change approach (using materials with enhanced magnetic sensitivity) improves detection accuracy while the GMR technology itself is well-established in semiconductor manufacturing, helping to manage manufacturing difficulty.

The patent employs a pulsed or transient current source to drive the coil, creating periodic magnetic field excitation. This periodic action optimizes detection effectiveness by generating time-varying magnetic fields that enhance the interaction with moving ferromagnetic targets, improving measurement precision. The pulsed nature of the current also helps manage energy consumption by activating the coil only during detection intervals rather than continuous operation.

The system uses the output signal from the magnetic field sensing element to detect changes in the magnetic field caused by ferromagnetic targets. This feedback mechanism allows the system to optimize detection by comparing expected field patterns with actual measurements, improving detection effectiveness while the selective activation based on detection needs helps manage energy consumption.