Reader for barcode magnetic characters and circuit arrangement for evaluating the bar edge timing values in such a reader

摘要

To achieve high reliability of detection in the case of CMC 7 magnetic characters, which may also be inclined, the read head (LK) is sub-divided into several tracks, two adjacent tracks AS1, 2-2, 3...13, 14 in each case being combined with mutual overlap by in each case one track to form one channel signal. The front-edge, rear-edge and separating-gap signals (VK, HK, LW) occurring in the individual channel signals are in each case allocated timing values which are temporarily stored in one timing-value buffer each (ZWP1...ZWP7) per channel. These timing-value buffers are connected serially by means of a channel control (KST) to an interval detection circuit (IES) which determines narrow and wide intervals from the timing values read out serially. From these intervals, individual, partially complete and partially incomplete interval sequences are formed for each channel and are transferred into an interval sequence register (IFR). These interval sequences are finally cyclically evaluated in such a manner that when a first complete interval sequence occurs, the evaluation of the further channel interval sequences is suppressed. <IMAGE>