Patent ID: 8928311
Filing Date: 2015-01-06
Classification: G01D

Abstract:
1. An electromagnetic induction type absolute position measuring encoder having two or more tracks, the encoder comprising: two or more rows of scale coils, each row including scale coils numerously arranged on a scale in a measuring direction so as to have a scale pitch different from that of another row; and a transmitter coil and a receiver coil provided on a movable grid relative to the scale in the measuring direction so as to face the scale coils, so that the encoder can measure an absolute position of the grid with respect to the scale on the basis of a flux change detected at the receiver coil via the scale coil when the transmitter coil is excited, wherein a coil line to be an added coil is connected to at least one side of the scale coil in the measuring direction at least in one of the tracks; three rows of the scale coils are provided; and the added coils are connected only to the scale coils arranged on an upper side and a lower side, respectively, and the added coil is not connected to the scale coil arranged at a center.