TMF Sensor

TMF sensors are Canon Electronics’ unique magnetic sensors, with the company handling everything from element development and manufacturing to product application. They aim to meet new magnetic detection needs with high performance and reliability, manufactured in Chichibu. The sensors are high-frequency driven magnetic sensors that use Canon Electronics’ proprietary magnetic thin films. There are two types of sensor elements available depending on the magnetic detection application: TMF-MI elements and TMF-FG elements. TMF-MI elements utilize the magnetic impedance effect, while TMF-FG elements use orthogonal fluxgate operation. The sensors combine excellent magnetic properties of thin films, processing technology that allows for high-degree-of-freedom elements, application technology that combines magnets and coils, and signal processing technology that obtains high S/N signals at high speed, to meet various magnetic detection needs. The company is also expanding its applications into the ultra-high sensitivity world, aiming for 1 pT resolution by leveraging the latest digital technology.

TMF-MI elements are driven by applying MHz pulse current to a magnetic thin film. The magnetic anisotropy of the magnetic thin film is set so that it has almost no permeability at zero magnetic field, and permeability rapidly increases when an external magnetic field is applied. Changes in permeability are reflected in the skin effect due to high-frequency current, changing the impedance of the element. The sensitivity of the element can be freely set by pattern design. TMF-FG elements apply high-frequency current to a magnetic thin film, magnetizing the magnetic flux generated by an external magnetic field within the magnetic material, and extracting the change in magnetic flux with a stacked coil. The signal shows a large change in even-numbered harmonics relative to the applied current frequency, and the sensor signal is obtained by a detection circuit. It has a slope at the origin and does not require a bias magnetic field. There are also types incorporating a negative feedback coil, achieving high linearity and excellent temperature characteristics.

For ultra-high sensitivity, especially in fluxgate sensors, the demagnetizing field of the magnetic thin film is thoroughly reduced, coils are external to increase turns, and signal processing involves detection at twice the frequency of sine wave current. In applications, combining two sensors and numerical calculation processing allows for extracting signals buried in noise with good S/N. The TMF sensor is not sold as a standalone element, and there are no standard products. Each application is handled individually.