Improvements in or relating to guillotine back stop control units

988,889. Guillotine cutting machines; punching. VICTORY - KIDDER PRINTING MACHINE CO. Ltd. May 22, 1963 [May 22, 1962], No. 19630/62. Heading B4B. A guillotine back stop control unit for cutting paper stacks comprises a tape 5, Fig. 1, which is driven by means 3 in synchronism with the movement of the back stop and is provided with a plurality of channels of control indicia, the portions of the indicia in the first channel corresponding to positions at which the back stop is to be halted in a first forward movement for a series of cuts to be made in the stack, the position of the indicia in the second channel corresponding to the stopping of the back stop in a reverse direction, and the positions of the indicia in the third channel corresponding to positions at which the back stop is to be halted in a second forward movement for a second series of cuts to be made in the stack which has been swung through right-angles after cutting of the first series. Sensing means 11 sense the positions of the indicia in the channels and switch means 21, Fig. 2, select the operative channel on the tape. As described, sprocketed Manilla tape punched with holes arranged in three parallel rows 38 ... 40, Fig. 7 (i.e. the above-mentioned control channels) is wound from a spool 6, Fig. 1, to a spool 7, and vice versa, by a conductive disc 3 bearing pins 4 and driven in synchronism with the movement of the back stop. A framework 10 movable towards the disc by a lever 12 carries two sets of sensing brushes 11a, 11b, each including three brushes which contact the disc 3 through the punched holes in the tape. An apertured disc 13 is mounted for movement with the back stop shaft 2, Fig. 2, and is engaged with corresponding apertures in the disc 3 by a pin 14, Fig. 1. In operation, a system of relays and switches provide for control of the machine in response to actuation of a switch 16, Fig. 2, having " Hand," " Manual," " Semi-automatic " and " Automatic " positions. In the " Hand " position the guillotine is operated by buttons 17 and the back stop by a wheel 35. The position is also used to set up the tape-programme, by moving the back-stop to the desired position, operating the disc clutch 13 by removing the pin 14 from the discs 3, 13, displacing the tape to a punching position corresponding to the distance between the brushes 11 and the punches 15, and reinserting the pin 14, the required hole being made by manual depression of an appropriate punch 15, and resetting the clutc