| 摘要 |
A positioning apparatus, and method of making same are disclosed, the apparatus including two relatively movable threaded nut and screw members with one of the members having detectable means thereon at intervals about the thread crests and the other having reading head means capable of detecting the detectable means wherein such apparatus is capable of precisely relatively moving its members by relative rotation therebetween and indicating both the magnitude and direction of movement of one member with respect to the other by detection of the detectable means.
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