Development of Electronic Compass for Automobile, Using Magnetoresistive Elements

These days, a variety of navigation systems have been developed to provide the driver with necessary information such as vehicle location, direction and destination. An electronic compass is being widely used as a component for such navigation systems (1), (2) and (3). Compared with a conventional magnetic compass, an electronic compass has the following advantages:

1. 1.
   High vibration durability and quick response.
2. 2.
   Easy to calibrate and reliable.
3. 3.
   Sensor and display units can be separated.

The electronic compass, however, is accompanied by two serious subjects: the development of a sensitive geomagnetic sensor, and calibration of direction error due to an unexpectedly magnetized vehicle body. First, we developed a new geomagnetic sensor utilizing magnetoresistive elements (MRE) and magnetic lenses. Next, we clarified the magnetic disturbances and defined the mechanism of vehicle magnetization, thereby establishing a simple calibration technique for such magnetization. As a result, the newly developed electronic compass has been in mass-production since May 1991.