Patent GB-653823-A (GB)
Title: Improvements in apparatus for registering flexible printing blocks, on printing rollers, especially for colour printing
IPC: G03F9/00
Filed: 1948-02-19
Abstract: 653,823. Printing-surfaces. NAVARRE, A. Feb. 19, 1948, No. 4917. Convention date, June 20, 1947. [Class 100 (ii)] Apparatus for registering corresponding points of flexible printing blocks on identical printing rollers 1, 2 in which the rollers are mounted co-axially for common rotation, comprises a sheet 12 of clear glass mounted so that it can be laid tangent to the rollers in a generally horizontal position and having a registering line 13 scribed thereon parallel to the roller axis and coinciding when the glass sheet is in operative position with the line of contact with the rollers, transparencies 15, 16 so supported that they can be laid on the glass sheet, one over each roller, and be moved all together in axial direction, their axial spacing being adjustable without disturbing their parallelism, each transparency having scribed thereon a registering line 17, 18 transverse to the roller axis and parallel to the other transverse line or lines, and a light projector 19, 20 mounted above each transparency and throwing a substantially vertical narrow beam, so that these beams cast sharp shadows of the several transverse registering lines and of the pairs of the axial registering line crossing them, and that the intersections of these shadows on the surfaces of the rollers define corresponding points in register with each other. The rollers 1, 2 are mounted on a shaft 3 and located thereon by adjustable collars 6 and are lockable to the shaft, which is rotatable by a hand wheel 7 whose rim has graduations 8 rotatable against a fixed mark. The glass sheet 12 is supported in side rails 10 of a U- shaped frame rockable on a fixed cross-bar 9 and having a counterweight 11. A cross-bar 14 supports a tubular member 21 rotatable and slidable thereon and lockable thereto, being mounted in end members which are only slidable. The transparencies 15, 16 are in the form of set squares slidable in a longitudinal slot in the member 21 and lockable thereto. The lines 13, 17, 18 are scribed on the undersides of the glass sheet 12 and transparencies 15, 16 respectively. The light projectors 19, 20 are mounted rigidly on the tubular member 21 and approximate closely to point-sources of light. One printing block of a set of colour blocks may be attached to the roller 1, the rollers locked to the shaft, and the set squares locked to the member 21 with the lines 17, 18 at a predetermined spacing. The wheel 7 and member 21 are moved until the intersection of the lines 13, 17 coincides with a selected reference point on the block on roller 1. The shaft 3 and member 21 are then locked in position. The glass sheet is raised, and a second block temporarily adjusted on the roller 2, to which a slow-setting adhesive has been applied. The glass is lowered and the second block manually shifted until the equivalent reference point thereon coincides with the intersection of lines 13, 18. This is repeated with a second pair of reference points. By simultaneous rotation of both rollers by means of the wheel 7 and by shifting of the member 21, the correctness of the circumferential and axial spacing of any number of pairs of reference points can be checked to ensure that distortion has not taken place. Pressure is applied to the glass sheet to cause the block to adhere to the roller 2, which is then removed to allow the adhesive to set. The Specification as open to inspection under Sectl 91 comprises also a method of temporarily attaching transfers to the under side of the glass sheet in correct register and thereupon rolling them off on to the rollers, the required motion between the glass sheet and the rollers being obtained by mounting the pedestal bearings of the shaft 3 on a bed-plate mounted in guides so as to be slidable horizontally perpendicular to the axis of the shaft, or by similarly mounting the support for the rockable frame. This subject-matter does not appear in the Specification as accepted.