GB1449605A - Code recognition - Google Patents

Abstract

1449605 Label reader UNILEVER Lid 19 Sept 1973 [21 Sept 1972] 43750/72 Heading G4M Labels on articles, e.g. in warehouse or automated or computer linked control systems having parallel rows of digital code markings, each row containing one digit, are reads using a television camera having its line scan aligned with the rows. The code used has wide or narrow bars which may be symmetrical about a centre line (Fig. 1 not shown) the narrow bars indicating a zero in a bit position and the wide bars a one. Each decimal digit may contain a wide space the position of which indicates the decade of the digit, e.g. a wide space between bits 3 and 4 indicates hundreds and between 1 and 2 indicates units. The codes may be non- symmetrical (Fig. 2 not shown) using similar wide and narrow bars but with non-symmetrical wide and narrow spaces to indicate the direction of reading. Coded articles A on a conveyer are scanned by the television camera C which feeds a conditioning unit D which removes high and low frequencies and noise and triggers a square wave having a background or white level and a mark or black level. A decoder E produces '0' and '1's from the video signals. In the decoder when a signal level changes a shift register is reset and a pulse is fed in. At the next signal level change the stage reached by the signal determines whether the mark is ignored because the signal is not shifted far enough, whether it is a '1' because the signal is situated betweeen predetermined stages, whether a error exists because the signal is between two further predetermined stages, whether the signal is a '1' for similar reasons or whether the signal has shifted too far and is an error or the end of the train. The binary signal is fed to the first half F of a shift register and sequentially proceeds into the second half. When the registers are full their contents are compared and if they differ a fault is diagnosed. If the comparison is correct the order determined by the wide space is obtained and the character is fed to memories J or K. The television scan is arranged so that at least three successive scans pass through each row and so three successive decodings of the data are compared using memories J,K and comparators L,M. I is a memory selector determining which memory the data enters. The fully decoded and correct signal is passed to units N and P for storage on tape or for use in a computer. Successive lines may use different codings which are fed to different decoders on reading.