Patent ID: 7906958
Filing Date: 2011-03-15
Classification: G01D

Abstract:
1. An electromagnetic induction type encoder comprising: a number of scale coils arrayed on a scale along the measurement direction; transmitting coils and receiving coils that are disposed on a grid relatively movably in the measurement direction with respect to the scale, which encoder detects a relative movement amount of the scale and the grid from changes in magnetic fluxes detected by the receiving coils via the scale coil when the transmitting coils are magnetized; wherein a plurality of sets of the transmitting coils, the receiving coils and the scale coils are disposed symmetrically with respect to the center of the scale, and scale coils of one set located at a symmetrical position around the center of the scale is disposed with ½ phase of the scale pitch shifted with respect to scale coils of the other set.