Patent GB-657133-A (GB)
Title: Photographic contact-printing apparatus
IPC: G03B27/12
Filed: 1948-10-06
Abstract: 657,133. Photographic contact printers. GRINTEN, L. P. F. VAN DER, GRINTEN, P. A. W. VAN DER, and GRINTEN, K. J. J. VAN DER, (trading as CHEMISCHE FABRIEK L. VAN DER GRINTEN). Oct. 6, 1948, No. 26100. Convention date, Oct. 6, 1947. [Class 98 (ii)] A photographic contact printer comprises a rotatable printing cylinder with a light source therein, means for feeding light - sensitive material around the greater part of the surface of the cylinder and for pressing the material against the surface, means for feeding a transparent original between the light-sensitive material and said surface, means for releasing the original from the cylinder, a counting device operated by rotation of the cylinder and arranged to record the number of said rotations, and adjustable means connected to the counting device and adapted to cause the device, after a pre-set number of rotations of the cylinder, determined by the adjustable means, to set in motion the said releasing means. The contact printer shown comprises a glass cylinder 1 having a tubular lamp 2 therein and being rotatable by the moving light-sensitive material 3 which passes round rolls 7, 11 and is pressed on to the cylinder. The surface of the cylinder has ducts 12 therein which, during the rotation of the cylinder, communicate with an air chamber 18 connected by a pipe 4 to a valve 6. This valve includes a rod 9 carrying pistons 13 and secured to a spring 16 and electromagnet 15 connected to a source of current through a switch 36. When magnet 15 is energized, the rod 9 moves downwardly so that the chamber 18 is connected via valve 6 and pipe 14 to a source of air pressure; when magnet 15 is not energized, chamber 18 is connected by valve 6 and pipe 8 to a source of air suction. Magnet 15 is energized when switch 36 is closed by a projection 33, 34 or 35 on a disc 65 carried by a ratchetwheel 30 that is rotated through one tooth by a pawl 29 each time a projection 25 on cylinder 1 contacts a pivoted lever 28 carrying said pawl. Cylinder 1 is provided with a projecting camsurface 35 for closing a switch 38 so that an electromagnet 20 is energized and causes a lever 17 to move downwardly against the pressure of a spring 21. The lower end of this lever carries a rotatable roller 26 with fingers 27 attached thereto and when the lever moves downwardly the roller and fingers displace the leading edge of a transparent original 10, positioned as shown with said edge engaging an abutment attached to a curved guide 22 having an opening 23 through which the roller 26 projects, so that said original can move around the cylinder between the material 3 and the cylinder surface. In use, an original 10 is positioned as shown and with switch 36 open and switch 38 closed, chamber 18 is connected to a suction source and lever 17 descends so that the original is caused to move with the cylinder 1. After each revolution of the cylinder, the disc 65 rotates through one tooth and, when one of the projections 33-35 contacts switch 36, magnet 15 is energized and the original 10 is blown off the cylinder and is guided at 19 out of the printer. After another revolution of the cylinder, switch 36 re-opens and, when switch 38 is closed by cam 37, a fresh original 10 is fed to the cylinder. Other forms are described wherein switch 36 is operated by a perforated strip and wherein two alternatively-operated counting devices are provided. Reference has been directed by the Comptroller to Specification 657,325.