Patent ID: 8648590
Filing Date: 2014-02-11
Classification: G01B,G01D

Abstract:
1. An induction detecting type rotary encoder comprising: a stator; a rotor configured to be rotated with respect to a rotary shaft, the rotor being disposed while facing the stator; a first transmitting coil disposed on a first surface of the stator, the first surface facing the rotor; a second transmitting coil disposed on the first surface to surround the first transmitting coil, the second transmitting coil being arranged in a concentric pattern with the first transmitting coil with respect to the rotary shaft; a first receiving coil disposed on the first surface; a second receiving coil disposed on the first surface to surround the first receiving coil, the second receiving coil being arranged in a concentric pattern with the first receiving coil with respect to the rotary shaft; a first magnetic flux coupling body disposed on a second surface of the rotor, the second surface facing the stator, the first magnetic flux coupling body magnetically coupling with the first receiving coil; and a second magnetic flux coupling body disposed on the second surface to surround the first magnetic flux coupling body, the second magnetic flux coupling body being arranged in a concentric pattern with the first magnetic flux coupling body with respect to the rotary shaft, the second magnetic flux coupling body magnetically coupling with the second receiving coil, wherein: the first transmitting coil is disposed between the first receiving coil and the second receiving coil; a distance between the second transmitting coil and the rotary shaft is larger than a distance between the second receiving coil and the rotary shaft; the first magnetic flux coupling body forms a first track for causing a periodic change for each rotation; the second magnetic flux coupling body forms a second track for causing a periodic change for each rotation; the second magnetic flux coupling body has a pattern of which an inner peripheral side is substantially continuous in a circumferential direction, the second magnetic flux coupling body includes a first wiring and a second wiring, and a magnetic flux coupling degree between the second transmitting coil and the first wiring of the second magnetic flux coupling body becomes larger than a magnetic flux coupling degree between the second transmitting coil and the second wiring of the second magnetic flux coupling body.