Method and apparatus for plotted in hz along pressure adjustment with preview and a preceding correction of setting faults

摘要

1,062,882. Automatic registration control. CEA-PEREGO S.p.A. March 13, 1964 [March 13, 1963], No. 10653/64. Heading G3R. In a system for automatically maintaining longitudinal register in multi-colour printing of a moving web, register error and rate of change of error control signals are derived from marks at each format on the web detected by a photo-cell which is operative for only a small angular movement of a printing roller. In Fig. 1, paper printed in one colour with registration marks Ic passes a second printing roller S2 which superimposes a second colour with registration marks IIc. The registration marks repeat at intervals corresponding to the longitudinal pitch of the printing and, in passing, respectively cause light to be reflected from lamps L1 L2 on to photo-cells CF1 CF2. After passing through amplifiers A1A2, the signals from the photo-cells control transistor flip-flop circuits C to produce, according to which of the marks occurs first, one or other of two signals for a period corresponding to the time interval between the two marks. The signal so produced comprises pulses the frequency of which is dependent on the speed of the web as determined by a tachometer generator DT. The pulses are integrated to produce a voltage corresponding in magnitude and polarity to the magnitude and sense of error in longitudinal registration. If a difference in timing of marks Ic IIc is desired this may be achieved by setting an integrating circuit Cb to delay one signal. An interrupter IC driven with the printing roller ensures that the photo-cells are only effective over a limited portion of the revolution to eliminate the effect of other printed matter on the photo-cells. To the error signal so derived is added a signal, corresponding to the rate of change of error, obtained by subtracting from the average of each group of four error detections the average of the preceding group of four error detections. These average signals are derived by digital computation and converted to analogue signals. The resultant error signal is effective to eliminate error automatically by operating through a circuit PCR a reversible servomotor MCII which adjusts a roller T2 in the appropriate sense to alter the length of paper between the first and second printing rollers. Operation of the servomotor is interrupted periodically to prevent over correction and correction continues until a signal corresponding to the amount of correction equals the resultant error signal. Error signals are inhibited during correction and digital stores are reset after each correction. Application to printing in more than two colours is referred to.