Patent GB-323325-A (GB)
Title: Improved construction of photographic projection-printing apparatus
IPC: G03B27/36
Filed: 1928-11-21
Abstract: 323,325. Hana, G. H. Nov. 21, 1928. Projection printing - apparatus comprises a cabinet provided with a door and enclosing (1) a vertically movable platform carrying the lightsource, negative, and projecting lens, (2) holders for sensitive sheets of different sizes, (3) provision for maintaining the lens in focus when the platform is moved to different positions to vary the ratio of enlargement, (4) a locking-device for the door, adapted to turn on the light-source when the door is locked and turn it off when the door is unlocked, and (5) holders for strip negatives and sensitive strip material. As shown, the cabinet 20, having a hinged door 21, encloses a vertically-adjustable apertured platform 28 which is supported by cords passing over pulleys 23, 24 to a counterweight 27, and is adapted to be arrested in any one of four different positions by stop devices on the interior of the casing. The upper surface of the platform supports a, housing 32 for an electric lamp 35, and carries a heatinsulating asbestos ring 31. Below the platform are secured an apertured plate 43 for supporting the negative holder 45, and lugs 46 in which are pivoted arms 47 supporting a lens panel 48 connected by bellows 50 to the plate 43. Lenses 53. 53a for alternative use are mounted in a slideway on the lens panel 48. Depending from the panel 48 is an inclined rod 53<b> bearing against a roller 54 secured to the cabinet, this arrangement serving to adjust the lens for maintaining focus in different positions of the platform 28. Guides are provided in the base of the cabinet to receive a. slide 59 containing a sensitive paper &c. strip, the end of the slide emerging from the casing being provided with an upturned handle 61 whereby the slide may be displaced longitudinally for successive printing operations. Above the slideways are arranged a fixed tray 63 and two hinged trays 65, 66, each adapted to receive a different size of sensitive paper &c., either of the trays 65, 66 being swung down, when required for use, to rest in the tray 63. Strip negatives may be placed between glass sheets in a slide 75 comprising a skeleton flanged frame provided with a pin 75d. A holder 45 is provided with guides to receive the slide 75, and with registering holes 45b for the pin 75d, whereby any image on the negative strip may be registered with the masking aperture 45<c> for projection through the lens. A modified holder is described for allowing several images of the strip to be projected at one time. The lamp 35 is controlled by a switch 72 connected by a link 70 with a lever 69 pivoted at one end to the exterior of the cabinet and bent upwards at its free end to form a retaining latch for a pin 68 carried by a catch 67 on the door 21, so that when the latch is in retaining position the switch 72 is on, and when the latch is moved downwards to release the pin prior to opening the door 21, the switch 72 is turned off. A swinging bar 75 retains the latch in depressed position while the door is open, and is displaced by the pin 68 to free the latch, and allow the lever 69 to be raised, when the door is closed.