Position measuring instrument

摘要

A longitudinal position measuring device for measuring the relative positions of two objects comprising a housing, a measuring scale, and a scanning unit for scanning the measuring scale. The housing is attached to one of the objects and a scanning unit is attached to the other of the objects by means of a fastening member and a connecting element. The scanning unit comprises a light source and four photosensitive elements. The measuring signal produced by the scanning unit and power to the light source are conducted by means of a cable through the connecting element and into the fastening member. The fastening member is rotatably mounted to the connecting rod so that the fastening member may be readily attached to the other object such as a machine cradle. The cable extends through a chamber located in the fastening member and is connected to an electrical box from which the scanning signals may be taken for conduction to either a display or an evaluation unit. The chamber is dimensioned to allow a sufficient length of cable to be stored so that undesirable stresses on the cable are not exerted during rotation of the fastening member about the connecting rod.