Patent ID: 8558534
Filing Date: 2013-10-15
Classification: B62D,G01D

Abstract:
1. A rotational angle detection device that detects a rotational angle of a detection target, the rotational angle detection device comprising: a rotational angle sensor that outputs a sine signal and a cosine signal of which output levels are changed in accordance with the rotational angle; a first rotational angle detector that detects the rotational angle based on the sine signal and the cosine signal, the first rotational angle detector detecting the rotational angle when the rotational angle detection device is in an ignition-on mode; a pulse signal generator that generates, based on the sine signal and the cosine signal, three-phase pulse signals that have edges corresponding to predetermined rotational angles of the detection target and that are set in such a manner that the predetermined rotational angles do not overlap each other and are at regular intervals; and a second rotational angle detector that detects the rotational angle based on the pulse signals when the pulse signals indicate an edge, the second rotational angle detector detects the rotational angle when the rotational angle detection device is in the ignition-on mode or when the rotational angle detection device is in an ignition-off mode, wherein when the rotational angle detection device is in an ignition-off mode and the second rotational angle detector detects the edge, the second rotational angle detector compares the detected rotational angle to a stored and previously measured rotational angle to determine whether the rotation angle detection device is rotating in a positive direction or a negative direction.