Patent ID: 7154263
Filing Date: 2006-12-26
Classification: G01D

Abstract:
1. A rotation angle detector, comprising: a rotator that rotates in engagement with an object; a first detector that rotates in engagement with the rotator; a second detector that rotates in engagement with the first detector; a first rotation-detecting section for detecting a rotation of the first detector; a second rotation-detecting section for detecting a rotation of the second detector; an auxiliary detector that rotates in engagement with the rotator; an auxiliary rotation-detecting section for detecting a rotation of the auxiliary detector; and a controller for detecting the rotation angle of the rotator from detecting signals fed from the first rotation-detecting section and the second rotation-detecting section, wherein, the first detector, the second detector, and the auxiliary detector each rotate at a different speed, the controller receives each detecting signal from i) the first rotation-detecting section and the second rotation-detecting section; ii) the second rotation-detecting section and the auxiliary rotation-detecting section; and iii) the first rotation-detecting section and the auxiliary rotation-detecting section to calculate at least two tentative values for the rotation angle, the controller employs the detecting signal received from the first rotation-detecting section and the second rotation-detecting section for detecting the rotation angle of the rotator when the calculated values are within a predetermined range.