US Patent 7219562 Angle sensor

The invention provides an angular position sensor (1) comprising two magnets (32, 33) attached to the inside face of a rotor (31) for generating a magnetic field (50) and a magnetism detection device (43) disposed in the magnetic field (50). The magnets (32, 33) are arranged substantially opposite each other with a pole of opposite polarity of each magnet (32, 33) directed towards the center of the rotor (31). A uniform magnetic field (50) is generated around the magnetism detection device (43) which provides more accurate sensor measurements over both small and large angles of rotation of the rotor (31). Furthermore, the magnets (32, 33) need only be axially magnetised which simplifies construction of the sensor.