GB1384554A - Opti'l contact printing machines - Google Patents

Abstract

1384554 Program control of printing ETABS ANDRE DEBRIE 15 Dec 1971 [16 Dec 1970] 58303/71 Heading G3N The spectral composition of a light beam used for contact printing using the three colour additive principle is changed automatically under programme control frame by frame in synchronism with the film to be printed to obtain colour effects. A notch in the film indicating a change of sequence, is read by an index feeler in unit Mo, which after a delay provided by Ro, corresponding to passage of the film notch to the projection aperture operates, via a bi-stable unit Bo, an electromagnet 10 which, between frames, impulsively sets the symmetrically disposed shutter members 3, 3' of each of three flux modulators to positions derived from binary information stored on a tape read by reader L, the light from an incandescent or halogen lamp having been split by a mirror or filtering foil system into red, green and blue components passing through the respective flux modulators, the resultant beams when recombined illuminating the film to be printed. Control circuit for shutter positions, Fig. 1. The signal from bi-stable unit Bo also, via pulse emitter Eo and spacing selector So enables, in succession, the storage in memories Ml, M2, M3 corresponding to the primary colours, of flux information derived from the tape via reader L. D.A. converters C1, C2, C3 provide an analogue signal via amplifiers Al and A1" to D.C. motor 16 driving a cam 18, Fig. 3 to an angular position corresponding to the next desired shutter setting, an actual position signal from motor driven potentiometer 21 via amplifier A<SP>1</SP>, of unit gain for temperature compensation being combined with the signal from A 1 for the position control. Potentiometer 23 is set in dependence on the chromatic response characteristics of the printing film. The information in the memories M 1 , M 2 , M 3 is cancelled after a predetermined time by a circuit (not shown). The tape is advanced under control of impulses from unit Bo. Flux modulators, Fig. 3, see also Fig. 2 (not shown). A housing 1 with aligned apertures (2), 2<SP>1</SP> through which light passes contains shutters 3, 3<SP>1</SP> geared together by gear-wheels 6<SP>1</SP>, 6, for simultaneous movement in opposite rotational senses. Rotation of the shaft (17) of motor 16 to its programmed position, via cam 18, and levers 14, 13 sets the angular position of a line joining rollers 15, 15<SP>1</SP> at a corresponding value, without moving the shutters, which are held by braking arrangement (7, 9), the former a disc on shaft (4) supporting gear-wheel 6. Upon energization of electromagnet 10, rollers 15, 15<SP>1</SP> are drawn by collar (11) into re-entrant faces of cam 5 on shaft (4) causing the latter to impulsively rotate until cam 5 is aligned with rollers 15, 15<SP>1</SP>, corresponding to the programmed shutter opening. The electromagnets of all three flux modulators operate simultaneously. Integrated circuit construction is used.