Patent GB-367903-A (GB)
Title: Improvements in or relating to cameras
IPC: G03B27/58
Filed: 1930-11-28
Abstract: 367,903. Roll-film cameras. POWERS, F. T., 205, West 39th Street. New York, U.S.A. Nov. 28, 1930, No. 35853. [Class 98 (i).] Provision is made for housing a number of rolls of sensitive material (paper, film, &c.) of different widths, and means for feeding any desired length of material from any one roll into the focal plane. Disclaiming reference is made to a particular construction embodying this feature in Specification 367,902 concurrent herewith. The camera described has also, (a) a retractable pressure plate ; (b) an associated endless belt, automatically started on retracting the plate for assisting the passage of the film into the focal plane, and its subsequent discharge therefrom ; (c) adjustable means for masking the upper and lower edges of the exposed film for regulating and centering the exposed area ; (d) means for severing the film at the edge of the exposure ; and (e) a half-tone screen holder, adaptable for any size of screen, and adjustable to and from the focal plane. The apparatus may be constructed as part of an enlarging outfit, Fig. 1, with a roller carriage 6 for the lens, a scale 9, and object holder 11. The back of the camera has closure doors and may be mounted in the wall or partition of a dark-room 13. A number of film rolls are mounted on shafts 22, 23, 24, Fig. 2, within an upper compartment of the camera, each film being fed by rollers 35, 37 through a separate channel (e.g. 31, 32 or 33) to a common exit slot 30 at the top of the focal plane and just behind a sheet of glass 84, Fig. 3. The feed rolls 35 are operated by external handles 67, Fig. 1. To facilitate threading the films, each pressure roll 37, Figs. 2 and 6, can be retracted from the operated feed roll 35, by lateral bars 52 which move slides 39 having slotted bearings 42 for the pressure rolls. The pressure rolls are normally pressed against the feed rolls by springs 46. To facilitate feeding the film into the focal plane and to press the film flat against the plate 84 for exposure, a reciprocating pressure plate 86, Fig. 3, is provided the framework of which carries an endless feed belt 112. The feed belt only operates when the pressure plate is retracted. The plate 86 slides on lateral guideways in the camera and is moved to and fro by an external handle 94 operating the shaft 92 and linkwork 95, 101, 105. The endless belt 112 is operated by feed rolls 115, 116 positively driven by a motor 135 through a flexible shaft 134. The starting switch 138 of the motor is moved by the lever 137 on shaft 92 when the plate 84 is retracted. For masking a central area of the exposure plate 84, two slides 166, 160, Fig. 3, are adjusted by screw shafts 162 which are operated by bevel gearing 170, 171, Fig. 2, from an external handle 188, Fig. 1, and the set position is indicated by a scale 186. In a modified construction, Fig. 19, the upper masking slide 166 has side racks operated by a pinion shaft, and the lower slide 160 is connected by cords 247, over pulleys 248 so as to move synchronously. For feeding a measured length of film, determined by the length necessary to reach the edge of the lower masking slide 160, a rack bar 74, Figs. 1 and 8, with an indicator 78 is moved along a graduated guideway 75 by a pinion 68 loosely mounted on the end of the feed roll shaft 37, and coupled therewith by a crown tooth clutch 65, 69, Fig. 16, and resilient spring 70. To provide for cutting off exactly the exposed length, the film is fed backwards after an exposure until the upper edge of the exposed length is adjacent the slot 30. The forward feed and subsequent backward feed are indicated by scales 76, 77, Fig. 8, used in conjunction with the scale 186, Fig. 1, used for setting masking slides. For cutting the exposed film a knife blade 145, Figs. 2 and 15, is mounted on a guided block 146 and is drawn across the slot 30 by a rod 149. A half-tone screen 227<1>, Fig. 3, may be adjustably positioned in front of the glass plate 84. Different sizes of screen may be used. The screen is mounted between cross-bars 224, 227 carried by vertical uprights 200 which are mounted on slotted blocks 201, 202, sliding in fixed guideways 203, 204. The screen is positioned by a handle 216, Fig. 1, on the shaft 214 by means of crank and lever mechanism 206, 213 and 205, 209 connected by links 211. The setting handle 216 is fixed in set position by a pin engaging holes in the hub shaft of the handle. For holding screens of different sizes the holding bars 224, 227 are pivotally mounted on sleeves sliding on the uprights 200, and positioned by spring catches 228 engaging spaced holes 230 in the uprights. The screen is held between bevelled edges 225, Fig. 3, on the bars 224, 227 and front lugs 226 thereon, and the pivot mounting 224a, Fig. 11, of the bars allows for irregularities in the edges of the screen.