Patent GB-277420-A (GB)
Title: Improvements in or relating to apparatus for x-ray photography
IPC: G03B42/02
Filed: 1926-06-15
Abstract: 277,420. Furby, C. W., and X-Rays, Ltd. June 15, 1926. R÷ntgen - ray apparatus; magazine hand cameras for roll fims.-In a portable apparatus adapted to be applied to the object to be radiographed, the film is adapted to be wound intermittently from one spool to another, and the portions of the film which are carried by the spools are screened by material impervious to R÷ntgen rays. In one form, the apparatus comprises a lead-lined box 10, Fig. 2, having an exposure aperture 16 closed by a sheet of thin wood 18 pervious to the rays, upon which is secured an intensifying screen 34. Spool holders 24, 26 are mounted on each side of the aperture 16, and the spool mounted on the holder 26 is driven to wind the film across the aperture 16 by gearing which is operated by an external handle, and includes a ratchet drive. Rotation of the handle through 180‹ counterclockwise winds a fresh length of film into the focal aperture, and an equal reverse rotation restores the handle to its initial position without moving the film. Hinged to the box 10, and connected to it by a jointed strut 20, is a lead-lined lid 14 having an aperture wherein is mounted a box 66 of sheet lead, the sides of which serve to support and guide a pressure plate 63 of wood carrying a second intensifying screen 64 which, when the lid 14 is closed, presses the film against the intensifying screen 34 in the exposure aperture 16. Arms 74 pivoted on the box 66 and connected by links 76 to the plate 63 are caused by springs 80 to apply the required pressure to the plate 63 when the film is stationary in the exposure aperture. On turning, the film-feeding handle to wind a fresh length of film, a notched cam 100 in the feeding gear train raises a lever 88 pivoted at 90 to the box 10, and causes a projection 94 thereon to lift a screw 84 on a pin 78 engaging the levers 74, so that the plate 63 is withdrawn slightly to permit free passage of the film between the intensifying screens during the feed movement. The cam 100 permits the return of the lever 88 at the end of the feed movement in order to restore the pressure on the film. The feeding gear train operates a numbered disc which indicates successive exposures. Within the box 66 is mounted a sheet of lead glass carrying a fluorescent screen 114 which may be employed for inspecting the image before the first length of film is wound into the exposure aperture 16. The box 66 may be provided with a removable or hinged lead-lined lid. An extension spindle may be provided on the film winding handle for use when the camera is operated in circumstances which render turning the handle difficult. During the film winding movement, the handle may either operate a. switch for cutting out the current supply to the tube, or alternatively may displace a lead screen over the exposure aperture. In a modified form of apparatus, the spool-holders, Fig. 8, are separate from each other, each being enclosed in a leadlined box 100. 102 having hinged bottoms, and light-trapped slots for the passage of the film. Pads 108 in the slot of the box 100 press tightly on the film, while pads 110 in the slot of the box 102 press lightly thereon. The lead lining in the box 102 is extended to form a spigot 112 round the film slot, which is adapted to enter a socket 114 round the film slot of the box 100, and the boxes are held together by latches 166. The spool in the box 102 is adapted to be rotated to wind the film by a coil spring 118 wound by an external key, the barrel 122 of the spring having ratchet teeth engaging a pawl 128, and a withdrawable locking-pin 130 being provided to hold the barrel as the spring is being wound. The strength of the spring is insufficient to overcome the pressure of the pads 108 on the film, so that winding does not occur when the locking- pin is withdrawn. A length of film 28 to be exposed is withdrawn from the box 100 by merely separating the boxes through any desired distance, which may be determined by chains or cords connecting the boxes. After exposure, the boxes are moved together again, and the spring 118 winds the exposed lengths of film on to the spool in the box 102. This form of apparatus is used when it is desired to bend the film to conform to the part of the patient to be radiographed, for example the throat, but it must be operated in a dark room.