Patent ID: 8290732
Filing Date: 2012-10-16
Classification: G01D

Abstract:
1. An absolute type linear encoder comprising: a scale comprising a plurality of tracks including a high-order track and a low-order track; and a detection head configured to detect a relative position to the scale, a relative posture of the scale to the detection head being adjusted when attaching the scale and the detection head to machine equipment that becomes an application object, the detection head receiving an output outputted from the low-order track at a plurality of cycles for the entire length of the scale to the high-order track; and a processing circuit configured to obtain the number of cycles of the low-order track by using a correction value obtained per correction pitch, the width of which is wider than the detection pitch, based on an error between tracks produced by a difference between the position of the high-order track to the detection head and the position of the low-order track thereto when the position of the detection head is detected at a detection pitch for the position correction thereof, an output value of the high-order track, an output value of the low-order track, and a cyclic ratio of the low-order track to the high-order track, and obtain the position of the detection head to the scale based on the number of the cycles and the output value of the low-order track.