Patent GB-1221366-A (GB)
Title: Character generation system
Inventor: GARDNER GERALD MARVIN
IPC: G06K15/10
Filed: 1968-08-15
Abstract: 1,221,366. Character generators for printing machines. STANDARD TELEPHONES & CABLES Ltd. 15 Aug., 1968, No. 39006/68. Heading G4H. A character generating system comprises a line input unit for assembling the data applied to the system into a coded character, a cyclic code generator giving serial codes representative of the characters and means for selecting at least part of the serial code and directing it to character-forming means. The characters are formed by a series of dots arranged in 10 columns and 20 rows. In one form the apparatus is designed to write a complete row of 20 characters at once, the top row of dots of all the characters being written in succession by the 220 electrodes of an electrographic recording head 16. The paper is fed under the head 16 by a cylinder 17. After the recording of all the top rows of dots, the second rows are recorded in succession, the paper having advanced the appropriate distance. Each character is represented by a coded series of 200 bits (each being one of the 10 x 20 matrix). There are possible 50 characters and code generator 8 has means for producing the 50 sequences of 200 bits. This may be achieved by using a 10,000-stage shift-register which is preset before each read-out with an appropriate pattern of bits. Alternatively a delay line may be used, the output being fed back to the input to recirculate the code pattern. In another arrangement the codes may be generated by shift-registers having gated feed-back loops and modulo-2 adders so that a desired sequence of bits is generated during successive cycles of the shift-register. The gates may be controlled to cause the generator to produce codes representing the 50 characters in turn. The code generator also generates a succession of outputs on 6 parallel leads indicating which character is at present being read out. Inputs in the same code representing a line of 20 characters are applied at A and entered into line store 2 or store 3, the stores operating alternately. Meanwhile the previous line of characters is read out of the other store and the characters compared in turn at 9 with the successive six-bit signals from the code generator 8. The comparator also receives a control signal from row counter 19 so that the output of the comparator applied to gates 10, serves to gate out only the first ten bits of the 200-bit train representing a character. During the recording of the next row a slightly delayed signal is applied by counter 19 to read out the next ten bits and so on. The ten signals and one blank position are applied via eleven buffer stores 11 and amplifiers 12 to a diode matrix which is controlled by a character counter 15 to distribute the successive groups of eleven bits to appropriate groups of eleven recording heads. Means may be provided to vary the spacing between characters. For this purpose a width recorder is provided giving an indication of character width for each character recognized by the comparator 9. This signal is applied to the counter 15, now working not in character steps but in dot steps. The counter 15 routes the signals to the recording heads appropriate to obtain the desired spacing.