GB641830A - Improvements in or relating to register control systems for moving webs - Google Patents

Abstract

641,830. Automatic web control systems. CROSFIELD, Ltd., J. F., and CROSFIELD, J. F. Jan. 27, 1948. No. 2456. [Class 38 (iv)] [Also in Group XL (b)] In a printing press, four colours, printed by successive rollers, are registered by marks, printed on the web by the rollers, and scanned by photo-electric cells. As shown, Fig. 2, the photo-electric cells scanning the .Y, Bu and Bk marks, formed by the yellow, blue and black rollers respectively, also scan the picture areas and are therefore rendered inactive, by an electronic switch, Fig. 6, except during the interval while the space R1, R2, marked by the red roller, is passing the scanning point. During the active period, pulses corresponding to R2 and Y, Bu and Bk are detected and produce D.C. voltages which operate the correcting servomotor which is energized cyclically after a predetermined number of revolutions by the time cycling switch. Registration of the red and black colours is effected by cells 4, 5 respectively, the pulse outputs of which, after amplification are applied to the electronic switch, Fig. 9, in which, upon the application of the pulse corresponding to R1, to the flip-flop valve 47, the grids 55, 56 of valves 57, 58 are rendered positive and the valves themselves conduct, and permit the passage of pulses due to R2 and Bk applied to 46, 61 respectively. The outputs. of 57, 58 are each applied through 64, 65 to trigger and integrating circuits, Fig. 10, and D.C. voltages corresponding to misalignment between the red and black are developed at either condenser 89 or 93 depending upon whether R2 leads or lags Bk. If R2 leads Bk, the flip-flop valve 67 is operated and causes 89 to charge for a period which is terminated when the pulse due to Bk is applied to valve 67 at 74. Integration of the pulses due to R2 therefore occurs at 89. Similarly, should Bk lead R2, the condenser 93 is charged to an extent depending upon the degree of misalignment, by the action of valve 58 in the flip-flop 76. Correction is effected by a D.C. motor, the armature connections of which are reversed by relays energized in accordance with the voltage at 89 or 93. Periodic energization of the motor is effected, after a given number of roller revolutions, by the relay 120, energized from valve 117, Fig. 11, which is controlled by the flip-flop valve 101. Pulses generated by R2 are applied, from 64, to the valve 101, which develops voltages at the grids 116, 115, by means of integrating circuits including condensers 112, 108, which are proportional respectively to the speed at which the registration system is to operate and to the number of revolutions of the press subsequent to the last correction. In an alternative form, the registration marks Bk, Bu, R, Y, may be on a single longitudinal path.