Patent GB-979178-A (GB)
Title: Improvements in scanning circuit arrangements for use in the automatic recognition of symbols
IPC: G06V10/10
Filed: 1962-05-21
Abstract: 979,178. Automatic character reading. SIEMENS & HALSKE A.G. May 21, 1962, No. 19438/62. Heading G4R. In a character recognition apparatus the rear end of a character is detected by storing the character signals in successive scans so as to obtain a line of solid black representing the projection of the character, and this is compared with the signals derived from the current scan, the end of the character being indicated when a series of black signals in the store corresponds with a series of white signals in the current scan, there being white signals in both the store and the scan on each side of the series. The character signals are applied at n Fig. 2 to an Or gate OGp and blocking gate SGp to a circulating register Rp through which the signals are stepped in turn by clock pulses T. The register holds one scan and it has feed-back to retain all black ("I") signals. At the end of the character, therefore, the register holds a projection of the character, a line of black signals. It also holds signals relating to another character on the line above and sometimes the adjacent character if this is an oplique stroke. Gates Gp00 and Gp10 look respectively for the both white and the black and white combinations in the store Rp and in the input n. As the scan m passes between b and o Fig. 1 the O-O condition is present and a store Sp00 is set. In the region o-u the 1-0 condition passes a signal to gate Gp0010 enabled by the store Sp00 and a store Sp0010 is set to enable gate Gz. In the region below u the O-O condition causes gate Gp00 to give an output. The output from gate Gp0010 is also applied to a counter Zp10 and the number of 1-0 conditions is counted. At a certain predetermined minimum count, the store Sp10 is set. It is reset if a maximum count is exceeded. Supposing the maximum is not exceeded, the gate GZ passes a signal when gate Gz gives an output i.e. at the occurrence of the second O-O condition at u. The number of black sections in the register is counted by a counter Vz operated through a differentiator Dv. At the second O-O condition (u) the count is transferred to a store ZSz and at the same time if there is an output from gate GZ, the count is also transferred to store ZSZ. At the end of the current scan the counts are entered into backward counters RZz and RZZ. During the next scan as the black sections are read out of register Rp the counters step back. The second black section is the character, the signals for which are to be passed to recognition circuitry without the signals for the neighbouring characters. The second pulse delivered from differentiator Dr brings the counters RZz and RZZ back to zero, the first stages being set. The output from the first stage of counter KZz is gated in gate G1 with the black signals from the register. An output 1 is given as long as the black character parts are present. The 1 signal is gated with the output of the first stage of counter RZZ which is not present unless a proper number of 1-0 combinations was counted by counter Zp10. Gate Gze gives an output ze for the duration the black signals are present at the register output. This signal is used for selecting the signals appropriate to the character in subsequent circuitry.