GB1136555A - Improvements in or relating to the printing devices - Google Patents

Abstract

1,136,555. Printing machine control circuits. ING. C. OLIVETTI & C. S.p.A. 28 March, 1966 [29 March, 1965], No. 13520/66. Heading G4H. In a printing machine of the kind having a hammer Ml &c. for each character position adapted to be operated at the correct instant to print from type members on a moving drum 1, the input being from a cyclic memory 14 having a cycle shorter than the interval between the instants when successive characters come under the hammers, the hammers are operated by windings EM1 &c. connected to thyristors TH1 &c. selectively conditioned by the store to be operated at the correct instants by a power pulse source. The cyclic memory 14 consists of a magneto strictive delay line with a recirculating gate 13. The complete line of characters recirculates in delay line 14 during the time taken for the drum 1 to move from one printing position to the next. Oscillator 11 controls the recirculation and also applies character pulses to a counter 12 which energizes lines U1 &c. in turn to open successive character gates G1 &c. The bits relating to each character are staticized at 10 and compared at 9 with bit groups read off a coded disc 3 on the end of the character drum. When a match occurs a signal appears on lead 22 to enable the gates G1 &c. The corresponding thyristor is thereby made conductive and is held in this state by a low voltage from a source 7. When all the characters have passed through the delay line 14 a high voltage pulse from source 7 draws sufficient current through those thyristors that are conducting to operate the corresponding print magnets. The line of print is thereby built up by printing all the A's, then all the B's and so on. When all the characters have been printed, the voltage from source 7 briefly becomes negative to reset the thyristors. The source 7 consists of a transformer having secondary windings connected to rectifying networks giving the desired voltage levels. These are switched in turn to an output lead by transistors connected to tappings on a delay line. A pulse applied to the delay line operates transistors in sequence to provide the desired succession of voltage levels. A Zener diode is used to stabilize the output voltage levels.