Patent GB-1007931-A (GB)
Title: Improvements relating to pattern recognition devices
Inventor: INGHAM WILLIAM ELLIS
IPC: G06V30/192
Filed: 1960-10-06
Abstract: 1,007,931. Automatic character reading. ELECTRIC & MUSICAL. INDUSTRIES Ltd. Jan. 5, 1962 [Oct. 6, 1960; March 4, 1961], Nos. 34282/60 and 7951/61. Heading G4R. In apparatus for recognizing characters the characters are scanned in a vertical raster and the signals entered into a number of serialconnected delay lines having means for detecting the arrival of pulses at predetermined points, the points defining a predetermined pattern and means responsive to the arrival of a corresponding pattern of pulses to produce a, signal indicative of the pattern. The character is scanned by a flying spot scanner and reflected or transmitted light is received in a photo-cell to produce, for each vertical scan, a series of pulses of variable length representing black areas cut. The black signals are used to gate pulses from a source 13 to an amplifier, so that each cut of the character is now represented by a burst of pulses which after amplification at 27 are applied to the input coil 37 of a magnetostrictive delay line 15. A pick-off coil 45 at the other end detects the pulses in the delay line, re-shaped at 48 and applied to the input coil of a second delay line and so on. There is a delay line for each vertical scan through the character so that the character is reproduced as a pattern of moving pulses in the delay lines. Sensing coils along each delay line sample the contents and the outputs of coils lying in predetermined patterns are combined by adding. The pattern most closely resembling the character sensed will give the highest output and may be identified by a threshold device with a fixed operating level or one derived from the outputs from all the combinations. Alternatively, sampling coils arranged in predetermined patterns may be serial connected in groups to add their outputs so that the group giving the highest output identifies the character sensed. The patterns of coils may recognize only particular character shape elements, such as vertical and horizontal lines, and signals representing these elements are then combined to recognize the character the different elements being differently weighted in each recognition circuit. Groups of four coils may be positioned on the delay line, the outputs being combined and applied to pairs of bi-stable cores. These switch if an area is detected containing more than a certain amount of " black " and the binary output is combined to recognize the character. The white parts of a scan may also be used to gate bursts of pulses on to a " white " line. These are applied to a second series of delay lines in the same way and sampled by coils to produce " white area " outputs which are combined with the " black area " outputs by subtracting them in recognition circuits. For this purpose transformers may be used, the black and white area signals being applied severally to primary windings wound in opposite senses. To accommodate misregistry of the characters the scan is arranged to cover a broad vertical strip including the character and the sampling coils are concentrated over a middle part large enough to cover the character. To prevent a false read out from the recognition circuits a delay device is provided to prevent a recognition if it is followed within a predetermined interval by another recognition signal. As a further safety measure a certain predetermined interval must elapse between one recognition signal and the next, this interval being the time between the scanning of adjacent characters.