Position-measuring device

摘要

In a position-measuring device for measuring the relative position of two objects, the graduated scale of a divided rule (M%) connected to one object is scanned by a scanning device (A%) connected to the other object. Since the graduation plane with the graduated scale lies outside the neutral plane (NE%) of the divided rule (M%), extensions and compressions of this graduation plane due to bending of the divided rule (M%) produce measurement errors. In order to compensate such measurement errors, the graduated scale consists of a first graduation (T1%) in a first graduation plane (TE1%) and of a second graduation (T2%) in a second graduation plane (TE2%); the two graduation planes (TE1%, TE2%) lie symmetrically with respect to the neutral plane (NE%) of the divided rule (M%). The first graduation (T1%) is scanned by a first scanning unit (AE1%) and the second graduation (T2%) is scanned by a second scanning unit (AE2%) of the scanning device (A%), and the periodic analog signals (S1%, S2%) delivered by the two scanning units (AE1%, AE2%) are mutually superimposed for the purpose of averaging and fed to an evaluation device (W%) for forming measured values of position (PM%) (Figure 5). <IMAGE>