Angle sensor is primarily used to measure the rotary angle between fix part and rotary part. Angle signal converts to circuit parameter after obtained by angle sensor, then further convert into electrical signal. Angle sensor can be divided into relative type, absolute type, contact and non-contact type. The regular non-contact angle sensor includes encoder disk type, grating type, capacitive type, inductance type and Hall type. Optical angle sensor has relatively better performance, but also more easily influenced by vibration. The application of electrical angle sensor has constrained by its stability. Magneto sensitive elements have been already becoming the mainstream of angle measurement due to its reliable performance. Current magneto sensitive elements contain Hall elements and magnetoresistance elements. The sensitivity and resolution of Hall elements are lower than magneotoresistances, and cannot be used for high-performance angle sensor.
Advantages of Magnetoresitance Angle Sensor
- Wide working temperature ranges which between -40 and 150 deg C.
- High accuracy and reliable, magnetic drift which generated by mechanical stress, temperature and aging have very little influence on the accuracy.
- Durable and non-contact measurement.
- Decrease cost price of the whole electromechinical system to some extent.
Applications of Magnetoresistance Angle Sensor
Magnetoresistance angle sensor has been widely used in automotive, industrial and consumer electronics. Typical application in automotive area includes windshield wiper, power window, adjustable seating and electronic throttle. Angle sensor embedded rotary encoders have been used for speed and position control as a standard part. Hence it might be supposed that rotary devices with measurement and control requirements are all magnetoresistance angle sensor’s era.
About Magnetoresistance Angle Sensor Magnet
The angle sensor magnet for AMR sensor need to provide strong enough and symmetric distributed magnetic field, whereas would cause following unfavorable situations:
- Distort output signals and causes angle sensor response delay.
- Non-uniform magnetic field will cause asymmetric distribution on the magnetic moment of the angle sensor.
- Anti-magnetic interference capability will reduce.
For GMR and TMR sensor, magnetic field provided by the angle sensor magnet is not as bigger as better. Angle sensor magnet for GMR/TMR sensor should supply a range of uniform magnetic field, and ensure the minimum assembly tolerance. In fact, assembly tolerance of the angle sensor magnet can be enhanced by adjusting its shape, dimension and air gap.
