The rotary encoder detects the magnetic field of a permanent magnet attached to the end of the rotating shaft using CMOS magnetic sensors (MAGFET arrays) set in a square arrangement. The rotation angle is calculated in real time by logic circuits integrated with the sensor arrays. Using a fine-pitched sensor array and a digital domain signal processing technique, a compact encoder with high resolution can be realized. A prototype sensor chip with dimensions of 4.3 x 4.3 mm2 is implemented. The CMOS rotary encoder can achieve the resolution of 10 bits per rotation.
|Block diagram of sensor chip||Arrangement of sensor chip and permanent magnet|
|Prototype Sensor chip|