Patent ID: 8265897
Filing Date: 2012-09-11
Classification: G01B,G01D

Abstract:
1. A rotation angle detector for detecting an absolute rotation angle of a detectable rotation body to be rotated a multiple number thereof, comprising: a first rotation body to be rotated as a cycle of a rotation angle Tc with corresponding to a rotation of the detectable rotation body; a first detecting unit for detecting the rotation angle of the first rotation body; a second rotation body to be rotated due to the first rotation body or the detectable rotation body, and to be rotated as a cycle of a rotation angle Tm with corresponding to the rotation of the detectable rotation body, that is different from the cycle of the rotation angle Tc regarding the first rotation body; a second detecting unit for detecting the rotation angle of the second rotation body; and a rotation angle detecting unit for detecting the absolute rotation angle of the detectable rotation body with reference to a first continuous signal for the angle to be detected by using the first detecting unit and to a second continuous signal for the angle to be detected by using the second detecting unit, wherein the individual rotation bodies is rotated with corresponding to the rotation of the detectable rotation body, and a rotation angle of the detectable rotation body to be rotated in a period of the individual rotation bodies to be rotated as 360 degrees is defined as the individual cycles of the rotation angle respectively; and in a case where either one of the first rotation body or the second rotation body is assumed to be as a main rotation body, the other one thereof is assumed to be as a substitutive rotation body, the detecting unit for detecting the rotation angle of the main rotation body is defined as a main detecting unit and the detecting unit for detecting the rotation angle of the substitutive rotation body is defined as a substitutive detecting unit regarding the first detecting unit and the second detecting unit, the rotation angle detecting unit detects a number of rotations regarding the main rotation body with reference to a difference of phases ΔT between the first continuous signal for the angle and the second continuous signal for the angle, and calculates the absolute rotation angle of the detectable rotation body to be rotated the multiple number thereof with reference to the individual continuous signals for the angle and the number of rotations to be detected by using the main detecting unit.