公开(公告)号：JPH08249676A

公开(公告)日：1996-09-27

申请号：JP951896

申请日：1996-01-23

Applicant: IBM

Inventor： TEIMOSHII SUCHIYUAATO GAADONAA ,  KIMURA MASATOSHI ,  DERUBAATO AREN HANSEN

IPC: G11B21/08 ,  G11B7/085

Abstract: PROBLEM TO BE SOLVED: To generate the linear position signal of a coarse adjustment carriage having an optical polarizing element regardless of the variation of the environment and one- directional position detecting device by providing a light source at one end of the moving range of the carriage and projecting a light beam toward the other end of the moving range, and then, providing the position detecting device near the other end of the moving range. SOLUTION: The coarse position detecting device 300 is fixed to a drive frame 206 near the outer limit of the moving range of a carriage 202 and incorporated with a light source which emits light toward the inner limit of the movement range of the carriage 202 and is composed of a collimating LED 302, etc. A one-dimensional position detecting device(PSD) 304 is fixed to a frame 206 near the inner limit of the moving range of the carriage 202 with the photosensitive surface of the device 304 being faced to the LED 302 and an optical polarizing element 306 is fixed to the carriage 202. When the element 306 is not fixed to the carriage 202, the light from the LED 302 is made incident to the PSD 304 at a reference position A. When the carriage 202 and element 306 approach the inner and outer limits of the moving range of the carriage 202, the light is polarized to a second and third positions (B') across an increasingly long distance. The position of the carriage 202 is calculated by using basic trigonometry.