GB712863A - Photographic contact-printing apparatus - Google Patents

Abstract

712,863. Photographic contact-printing. KENNEDY INSTRUMENTS, Ltd. March 3, 1953 [March 7, 1952], No. 6059/52. Class 98(2) Photographic contact-printing apparatus of the kind described in Specifications 687,368, 687,369 or 712,862 includes means for urging the rolling plate or cylinder to its rest position constituted by a sloping bed to the apparatus whereby the plate or cylinder is urged to its rest position by gravity, or by means of a tension spring or like device, and timing apparatus comprising a spring-actuated sear adapted to hold the plate or cylinder in the working position, a pivoted lever carrying a gear wheel driven at a constant speed, one end of the lever being located so that when the plate or cylinder or - its framework engages with the sear, the lever is pivoted to bring the gear into mesh with a second gear, means for presetting the rotational position of the second gear, and a stud on the second gear which at one point in its rotation engages with mechanism which depresses the sear to release the plate or cylinder or associated framework. The mechanism, Fig. 2, is mounted on a plate 1. A bell-crank lever 2, pivoted at 5, is spring-urged clockwise to raise a sear 3 formed at one end. A gear wheel 6, spring-urged clockwise and carrying a stop (not shown) is pivoted to plate 1. A disc 8, inscribed with a time scale, lies over gear wheel 6 and has a stop below the zero mark of the scale against which the stop on gear wheel 6 is urged. A lever 11, pivoted at 12 to plate 1, carries a gear wheel 15 driven by a constant speed electric motor. When the rolling plate or cylinder of the printing apparatus is moved into working position, a part 22 connected thereto moves lever 11 against a stop 20 and engages gear wheels 15, 6. The part 22 is engaged by the sear 3, which thus retains the plate or cylinder in working position. The motor drives gears 15, 6 until the stop on gear wheel 6 engages lever 2 to lower sear 3 which releases part 22, allowing the plate or cylinder to return to rest position. The time at which this occurs depends on the starting position of the stop on gear wheel 6, which is set by adjusting the disc 8 according to the scale thereon. The disc is clamped after adjustment to the body of the apparatus by a wing- nut 21. The sear may also be depressed by hand by means of a lever 16 pivoted at 17, acting on lever 2 through a cam 18 pivoted at 19. The pivots 5, 17, 19, 20 may be formed by bolts attaching the timer to the printing apparatus. Switches may be provided switching the motor on and off as levers 11 or 2 are rocked. The levers 2, 16 and cam 18 may be combined as a single lever.