A device for checking longitudinal registration on machines for performing repetitive operations on a continuous band

摘要

934,728. Automatic alignment control. G. DALL'OGLIO, A. DE MARSICO, and G. CARNEVALI. May 18, 1961 [May 18, 1960], No. 18228/61. Class 38 (4). In a machine for registering multi-colour printing, a number of rollers are geared to a shaft driven by a main motor, the first roller being coupled directly to the shaft, and the other rollers being each coupled through a differential connected to a servomotor for independent rotation of the rollers to correct their respective positions. Reading heads check the relative positions of marks printed on the paper by respective rollers, or a mark printed on the paper is checked against one engraved on a subsequent roller. An impulse generator, coupled to the main driving shaft, is connected to a high-speed electronic counter 10, a reference head 6 and control head 7 supplying pulses to a starting circuit 8 for the counter. The interval between the pulses represents the positional error, and during this interval the counter 10 registers the pulses from the generator 5. The heads 6, 7 are also connected through sign detector 9 to error-correcting devices 11, 12, which are selectively effective in accordance with the sense of the error. Thus, when the counter 10 has finished counting the number of pulses corresponding to the error, one or other of the devices 11, 12 come into operation for correcting the error. A pulse generating device 13 is coupled to the error-correctors 11, 12, and is connected to the counter 10 for stopping the correction device when the correction has reached a value corresponding to the magnitude of the error. The device 13 may either reduce the number counted in the device 10 to zero or it may stop the correction before zero is reached to allow for inertia. In another embodiment, the generator 5 is replaced by a constant-frequency generator the pulses from which being counted during the interval between the pulses emitted by a reference head and a control head, as in the previous arrangement. A third head is placed at a fixed distance from the reference head and reads the same mark. A second counter records the number of generator pulses between the pulses emitted respectively by the reference head and the third head, and a device connected to both counters determines the ratio between the counted pulses and actuates a correction device, such ratio being independent of the speed of the paper.