Staas & Halsey
Reference-point return method
 The invention relates to a reference-point return method for returning a movable element of a machine to a reference point using solely a linear scale, without relying upon a limit switch. The method includes providing the linear scale (1) with a second scale portion (2) for stipulating a deceleration starting position and a reference-point position, in addition to first scale portion (3, 4) for generating two-phase signals for position detection, generating signals (S.sub.1, S.sub.2) indicative of the deceleration starting position (D) and reference-point position (O) from the second scale portion (2) of the linear scale, slowing a reference point return rapid-traverse velocity (Va) to a reference-point return rapid-traverse velocity (Vb) using the deceleration starting signal (S.sub.1), and effecting return to the reference point by stopping movement in response to the reference-point signal (S.sub.2). 
Fanuc Ltd.
G G G
G05B G05B G05B
inventional inventional additional
Shigeyuki Mitsuyuki Hirofumi Keiji
Ushiyama Taniguchi Kikuchi Sakamoto