ROTATIONAL POSITION DETECTION APPARATUS

摘要

PROBLEM TO BE SOLVED: To improve reliability of a mechanism for detecting that a drive gear is on an origin position and to prevent an electric circuit from being complicated.SOLUTION: A rotational position detection apparatus includes a measuring gear 62 having a different number of teeth to be engaged with a drive gear 32, a drive gear sensor 67 for detecting one position in a circumferential direction of the drive gear 32 and a measuring gear sensor 64 for detecting one position in a circumferential direction of the measuring gear 62. When the drive gear 32 is on an origin position, the measuring gear 62 is also on the origin position and both the sensors 67 and 64 are in detection states. When the drive gear 32 is rotated by 360°×n from the origin position and the drive gear sensor 67 is in a detection state, the measuring gear 62 is rotated over 360°×m from the origin position and the measuring gear sensor 64 is in an undetectable state.