Patent GB-1021446-A (GB)
Title: Improvements in or relating to magnetic tape control means
Inventor: JACKSON JOHN ALFRED
IPC: G05B19/16
Filed: 1963-04-04
Abstract: 1,021,446. Programmed control of guillotines. E. K. COLE Ltd. March 31, 1964 [April 4, 1963], No. 13317/63. Heading G3N. A programme control system for a papercutting guillotine as disclosed in Specification 961,505 is modified to permit a backfence to be arrested in a position intermediate of rear and forward limit positions. As shown, a mesh on a twin track magnetic tape, moved in synchronism with the back-fence, is read by a head A and a pulse passed through an amplifier 1, pulse clipper 2, pulse generator 3, counter drive 4, pulse counter and store 5 to a backfence slow down mechanism 6 so that the paper approaches a cutting position at a slow rate. The marks are then read by heads B, B1 causing pulses to pass through amplifiers 7, 7a, chopper 8, 8a, pulse generator 9, 9a. The pulse, or pulses is accepted by an and/or gate 10 and passed to a monostable circuit 11 to operate a contactor 12 to arrest the backfence. Coincidence of pulse from generators 9, 9a is sensed by a coincidence gate 13 to actuate a knife circuit 14. The completion of the knife operation pulses on lines 16, 17 cause the pulse to be removed from store 5 and the coincidence gate 13 restored to its original state. To arrest the backfence in partial forward and rear limit positions additional marks are recorded on the track scanned by the head B1 which cause the backfence to stop and a pulse to be developed by an anti-coincidence circuit 18 in response to a pulse from generator 9a in the absence of a pulse from a generator 9c fed from amplifier 7. The negative pulse from circuit 18 changes the state of a monostable circuit 22 and a bi-stable circuit 19 which sends a signal to an input of a bi -stable circuit 20 receiving its other input through a delay circuit 21 from a terminal Y when the back-fence stops, to actuate a reversing contactor for the backfence drive through a terminal X. Since the backfence overshoots the mark during the reverse movement the signal from the bi-stable circuit 20 is fed to charge the state of a bi-stable circuit 23 and cause transistors T2, T3 to conduct and prevent the pulse from circuit 18 passing along the leads to which their collectors are connected. During reverse movement circuit 13 is rendered inoperative, by a signal from the reversing contactor, to prevent coincident pulses operating the knife mechanism 14. The reverse movement continues until a rear partial limit mark passes the head B1 which causes a pulse to be developed by circuit 18 to remove one input to circuit 20 switching off the reversing contactor. On initiating the next programme by the operation of a forward push button a signal from the pushbutton is applied to a terminal 2 to change the state of circuit 23 and render conductive transistors T2, T3, T4 of which transistor T4 prevents the pulse from circuit 11, due to the repassing of the rear partial limit mark, from reaching the forward contactor 12. The transistors T2, T3, T4 are subsequently open-circuited the circuit 22 reverting, after a delay, to its original state and changing the state of circuit 23. The energization of transistors T2, T3, T4 and change of state of circuit 23 during a check on the programme, necessitating the operation of the forward push button, is reversed by a monostable circuit 24 responsive to a pulse through a terminal E when the knife circuit 14 is de-energized by the operation of the forward push button, the circuit 14 only being energized at a programmed cut point. It is stated that the programme may be recorded on magnetic wire.