GB544830A - Improvements in or relating to register control apparatus for maintaining the operation of a rotating element on a travelling web in register with any prior conditioningof said web - Google Patents

Abstract

544,830. Automatic control systems for multi-colour printing. CHAMPLAIN CORPORATION. Jan. 29, 1941, No. 1188. Convention date, Feb. 27, 1940. [Class 38 (iv)] [Also in Group XL] . Registration -control apparatus maintaining the operation of an element on a travelling web in register with any prior conditioning of the web comprises light-sensitive electrical means controlled in accordance with the pre-conditioned portion and other light-sensitive means controlled in accordance with one limit of tolerance and the position of the element and a device for indicating the need for, or performing, a correction when the error in register exceeds the limit of tolerances. Preferably photo-cells produce impulses which co-operate in the control of the anode current of a single space discharge device. Marks 14, printed by a cylinder 13, passing in front of a light beam cause a photo-electric cell 38, or the like, and amplifying valves 61, 62 to produce voltage variations simultaneously in the grids 65A, 65B of valves 65, 66. A member 45 in apparatus 111 having slots 46, 47 defining both tolerance limits is rotated in step with a second printing cylinder 17 to admit light to photo cells 50, 51 respectively whereby amplifiers 102, 109 are caused to produce voltage variations on grids 65B, 66B normally before and after the variations on the grids 65A, 66A. When the tolerance limit is passed in either direction the appropriate valve 65, 66 receives corresponding and simultaneous voltage changes on both grids whereby it passes current to energize a relay 75 or 80 energizing a capacitor motor 27 in a direction causing longitudinal movement of a worm 22 to correct the registration of the cylinder 17. The limits of tolerance may be adjusted by circumferential movement of the cells 50, 51 in relation to the slots 46, 47 and the construction of the register control apparatus 111 provides facility for jointly adjusting their optical systems in the same and in opposite directions. The relays 75, 80 also operate upon the grid circuit of a valve 85 so as to energize a relay 84 to open the plate circuit and the valves 65, 66 to stop the correcting movement of the motor after a time interval determined by adjustment of resistances 90, 92 in the circuit of a condenser 97 in the grid circuit of valve 85. Lamps 70, 79 indicate incorrect registration. When the colour of the registration work 14 is yellow a photo cell having a rubidium surfaced cathode in a bulb of lime glass is used in association with an optical filter transmitting the blue end of the spectrum predominantly.