Patent GB-290654-A (GB)
Title: Improvements in or relating to machines for photographic printing from tracings, negatives and the like
IPC: G03B27/22
Filed: 1928-03-29
Abstract: 290,654. Petit, L. May 20, 1927, [Convention date]. Printing-apparatus with continuous movement of negative and printed surface.-In a printing machine in which the sensitized paper, drawn from a supply roll, is driven together with the negatives over the surface of a stationary glass plate by means of an endless driving band provision is made for (1) feeding the free end of the roll of paper on to the driving band, comprising a bar, preferably of wedge shape, mounted transversely of the paper and so arranged that during the feed movement of the bar the paper is folded and introduced over the whole of its width under the driving band; (2) for correcting any tendency to lateral creeping of the paper on the printing platen, (3) for severing the paper when printing is finished, (4) for separating the negatives from the printed paper on delivery from the printing zone, and (5) for continuous displacement of the printing lamps at constant speed without appreciable slowing up at the ends of the travel. In the form shown, the machine comprises a curved glass platen 2 enclosing printing lamps (not shown), and an endless feed-belt 3 guided round the platen on rollers 4, 4<1>, 4<11>, the roller 4 being driven through a clutch 66 from a motor 63. The sensitive paper roll 11 is mounted on a shaft 12, which may be adjusted axially to correct for lateral creep of the paper on the platen 2, and is braked by a counterweighted wiper 17. To introduce the paper, a lever 30, held in mid-position, Fig. 1, by springs 31, 31<1>, is raised, and through links 29, 28 raises a wedge 25 into the position 25<1>, Fig. 2. The end of the paper is pushed through a gap between the belt 3 and a pressure roller 19 mounted on a bell-crank lever 37. Further upward movement of the lever 30 causes the lower end of the link 29 to engage and rock the bell-crank lever 37 so that the roller 19 presses the paper on the moving belt 3 and causes it to be fed along guides 21 and between a fixed block 22 and a cutting blade 23 into the position 24, Fig. 2. On now depressing the lever 30 the roller 19 releases the paper and the wedge 25 is moved into the position 25<11>, carrying the end of the paper between a spring plate 5 and the endless band 3, whereby it is carried round the platen 2. The lever 30 is then released, and the wedge resumes the position 25 to allow introduction of the negative between the moving paper and the spring plate 5. When the paper emerges from the end of the platen 2, the operator lifts a partition 6 into the position 6<1>, and attaches the end of the paper to the hub 7 of a store reel driven by a friction roller 10 from the motor 63. The negatives 8 are retained by the partition 6, and fall into a receptacle 9 when the partition is lowered. When the last negative has been fed to the machine, a lever 41 is quickly raised, causing a wire 39 stretched between the arms 40 of the lever, and resting normally in a groove 38 in the block 22, to move the paper against the cutting blade 23 and sever it right across, so that the feed from the roll 11 is arrested. A modified machine is described in which the sensitive paper moves from left to right through the machine instead of downwardly. The Specification as open to inspection under Sect. 91 (3) (a) describes also means for reciprocating the printing lamps along the axis of the platen 2. The lamps are attached to an endless cord passing round pulleys 45, 47 at opposite ends of the platen, and guide pulleys 46. A pinion 49 on the pulley 45 engages a rack-bar 50 connected by a link 52 to a bar 54 having a con. tinuous rack 55 engaging a pinion 60 driven through worm-gearing from the motor 63, whereby the lamp cord is continuously reciprocated to an extent variable by rotary displacement of an adjusting pinion 58 engaging a rack slot 57 in the link 52 and a fixed rack-slot 57<1>. This subjectmatter does not appear in the Specification as accepted.