| 摘要 |
In a code read-out method and apparatus, a code carrier is in the form of a circular plate of non-magnetic material having, on one surface, clock indicia in the form of concentric, uniformly spaced annular bands of magnetic material and having, on the opposite surface, signal indicia in the form of concentric, selectively spaced annular bands of magnetic material, each opposite a different respective clock indicia. The code carrier is passed along a detection path and between a pair of magnetic pick-up heads which are disposed directly opposite each other, and each of which is associated with a different respective surface of the plate. Both heads are connected in parallel to an AND circuit and to an OR circuit. The OR circuit provides an output pulse responsive to detection of an indicia on either surface of the plate. The AND circuit provides an output pulse responsive only to simultaneous detection of indicia on both surfaces of the plate. Thereby, the output clock pulses are readily discriminated from the output signal pulses. Preferably, the magnetic material is imbedded in annular channels in the plate surfaces. |
