Patent ID: 7196442
Filing Date: 2007-03-27
Classification: G01D,H02K

Abstract:
1. A motor encoder having: a bipolarly magnetized rotational body fixed coaxially on a motor axle; an X-phase magnetic sensor and a Y-phase magnetic sensor which are disposed facing an external peripheral surface of the rotational body and which output an X-phase signal and a Y-phase signal in the form of sinusoidal waves that differ in phase by 90° in association with the rotation of the rotational body; a rotor angle computing circuit for computing at prescribed cycles a rotor angle θa of a motor rotor on the basis of the X-phase signal and Y-phase signal; a magnetic pole signal generating circuit for generating three-phase magnetic pole signals U, V, and W that differ in phase by 120° on the basis of the number M of magnetic poles of the motor and the computed rotor angle θa; and an AB-phase signal generating circuit for generating an A-phase signal and a B-phase signal at predetermined cycles that differ in phase by 90° on the basis of the rotor angle θa computed at prescribed cycles.