Patent GB-925347-A (GB)
Title: Improvements in or relating to photographic contact printing or copying machines
Inventor: BAGLOW DENIS VAUGHAN
IPC: G03B27/30
Filed: 1958-06-16
Abstract: 925,347. Photographic copying machines. BLOCK & ANDERSON Ltd. June 12, 1959 [June 16, 1958], No. 19198/58. Class 98 (1). A photographic contact printing or copying machine comprises a transparent cylinder-as at 14-rotatable about an internal light source -as at 33-in combination with an endless belt drive system-as at 15-which embraces a major part of the cylinder surface to provide a conveyance path around said light source for paper sheets fed between said cylinder and said belt system from a sheet entry position to a sheet discharge position, a sheet feed table-as at 57-for supporting sheets adjacent said sheet entry position and intermittently operative sheet feed means-as at 53, 48-controlled by the rotation of said cylinder to commence feeding of a sheet placed on said table along an input path to said sheet entry position at a predetermined angular position of such cylinder during each rotation thereof, alternative lay stop means adjacent said sheet entry position comprising a master sheet lay stop-as at 63- movable between an operative position for registering the forward edge of a master sheet on said feed table prior to feeding thereof and an inoperative position clear of said input path and a copy sheet lay stop-as at 64-similarly movable between an operative position for registering the forward edge of a copy sheet on said feed table prior to feeding thereof at a position further from said sheet entry position than said master lay stop, and movable copy sheet deflector means-as at 37-adjacent said sheet discharge position also controlled by the rotation of said cylinder, the arrangements being such that the leading edge of a master sheet fed into said conveyance path during one revolution of said cylinder with said master sheet lay stop in operative position is positioned sufficiently in advance of the leading edge of a copy sheet fed into said conveyance path during a subsequent revolution of said cylinder with said copy sheet lay stop in operative position to allow said sheet deflector means to move into deflecting position behind the leading edge of the emerging master sheet but ahead of the leading edge of the overlying copy sheet so as to deflect only the copy sheet away from said cylinder. The belt drive system 15 comprises a plurality of endless belts passing over rollers 16-18, 20 and 21, 18 of which is spring urged to maintain tension in the belts and 17 of which is driven by an electric motor 28 through a speed reducing gear-box 27, sprockets 26 and 23 and a chain 24. Mechanism for controlling operation of the various movable parts of the machine in phased relationship to the rotation of the cylinder includes three cam discs (101- 103, Figs. 1 and 3, not shown) coaxial and rotatable with the cylinder and a system of levers. This control mechanism is not described in detail here. Operation of the machine once the motor 28 has been started is as follows. To prepare the machine for insertion of a master sheet to be copied, an operating bar 96 is raised, whereupon a lay stop rocker arm 61 carrying the stops 63, 64 is moved into a horizontal position in which stop 63 is operative and a driven roller 53 on a pivoted plate 54 is locked in a position out of contact with a free roller 48 as it is next lowered by said control mechanism (it is lowered once during each rotation of the cylinder 14). The master sheet may now be placed on the table 57 with its leading edge against the stop 63. On subsequent lowering of the bar 96, said control mechanism operates to raise the roller 53 into contact with the roller 48, whereby the master sheet is fed to the sheet entry point and on to the cylinder at a predetermined position relative to the cam discs. At the same time, arm 61 is returned to the position shown, in which stop 64 is operative. The master sheet rotates with the cylinder 14 and as its leading edge approaches a separator member 37 and a master stripper member 40, these are pivoted (by the control mechanism) away from the cylinder so as to allow the master sheet to continue to travel in contact therewith. The member 40 becomes locked in its pivoted position but the member 37 continues to be rocked each time the master sheet passes. Guide plates 42 guide the master sheet to a rapidly rotating brush 44 which pulls the master sheet taut as it passes by and re-presents it at the entrance point. Insertion of copy sheets: A copy sheet, e.g. of diazo type material, may be inserted (when ever the roller 53 is lowered) by placing it on the table 57 with its leading edge against the stop 64. When the roller is raised again, the sheet will be fed on to the cylinder 14 with its leading edge displaced behind that of the master sheet. The two sheets then travel together for exposure by the mercury-discharge lamp 33 as far as the member 37. This is pivoted back towards the cylinder after allowing the leading edge of the master sheet to pass therebeneath so as to deflect the copy sheet away from the cylinder. The sheet is then transported in frictional contact with the belts 15 to a developing section, guide members 71 and rollers 73, 74 being provided for this purpose. To remove a master sheet from the machine, the bar 96 is again raised (this can only be effected when roller 53 is lowered or being lowered). The master stripper member 40 is thereby released and pivoted towards the cylinder so as to deflect the master sheet off the cylinder and out of the machine over the discharge plate 66. The developing section: When a copy sheet reaches the end of the upper stretch 22 of the belts 15, it is guided by plate 75 to pass between driven rollers 83, 77, where developer solution is applied from interconnected liquid troughs 81, 83 supplied from a tank attached to the side of the machine. The sheet is then fed between squeeze and conveyer rollers 84, 85 and comes to rest lying on grid-like support wires 95 of transfer tray 94, with its rear edge lying on a free roller 86. Heating may be applied here to assist in the drying. After a short interval, one of said cam discs engages a nose 104 of a lever 105 and, through a coupling member 108, raises the roller 86, carried by rocket arms 87, into contact with a roller 88, which is continuously driven at high speed by a motor 90. The copy sheet is thereby propelled through the convergent throat of plates 92, 93 into a final delivery tray 67. Exposure time is controlled by altering the speed of the motor 28 by a variable resistance. Visual indicating means or an additional stop may be provided, controlled by said control mechanism, to prevent insertion of copy sheets except when roller 53 is lowered. Members 94, 67 and 58 are constructed so as to form part of the easing 10 of the machine when this is not in use. Specification 925,348 is referred to.