Patent GB-549194-A (GB)
Title: Improvements in or relating to photographic cameras
IPC: G03B17/42
Filed: 1942-01-22
Abstract: 549,194. Radiographic apparatus ; photographic copying cameras. KODAK. Ltd., NAGEL. H., and CROOKS, J. L. Jan. 22, 1942, No. 935. [Class 98 (i)] A camera, particularly for photographing X-ray screen images, is provided with a switch for connection to exposure-controlling means, the switch being closed by the manual operation of the film feeding means and the switchclosing means being held against return by a latch which is automatically released, for example by an electromagnetic device, simultaneously with or after the operation of the exposure-controlling means, multiple exposures on the same exposure area of the film being thus prevented. As shown, a camera C and a fluorescent screen are mounted at opposite ends of a squaresectioned conical tunnel 2. The perforated film is fed through a film gate 13 by a sprocket on a shaft 15, the the shaft being rotated through approximately a half-turn at each feeding movement by a handle 18, loosely mounted on the shaft, through a pawl 24 and a double-toothed ratchet 25 secured to the shaft, the movement of the handle being limited by stops 19, 20 engaged by a pin 21 moving with the handle. The film take-up spool is rotated by a cross belt drive 17 from a pulley on the shaft 15. Towards the end of the movement of the handle the pin 21 engages and rocks a pawl 48 so that it moves the arm 46 of a micro-switch in the X-ray tube energising circuit to the closed position. The handle 18 is prevented from returning by the engagement of a pawl 68 with a shoulder 69 on a plate 22 moving with the handle. The tube may now be energized to take the photograph by closing a thumb switch, causing a condenser discharge through the tube, upon which a relay is operated to energize a solenoid (not shown) which disengages the pawl 68 so that the handle 18 is returned to the position shown by a spring 28. The pawl 68 may be held in the release position by a lever so that the film may be wound without exposing it. In front of one corner of the screen is a casing in which is slid an interchangeable identification panel. Lamps in the frame are illuminated when the relay above referred to operates, so that the matter on the panel is photographed subsequently to the image on the screen. The lamp circuit includes the solenoid which releases the pawl 68, so that if a lamp filament breaks the handle 18 is not returned to the starting position, thus warning the operator. Further, a switch in series with the micro-switch above referred to opens unless held closed by the indentification panel, thus preventing a photograph being taken unless the panel is in position. The opening in the camera front is closed by a hinged spring- urged flap 33, Fig. 8, when the camera is removed from the tunnel 2. When the camera front is attached to the tunnel, by sliding it in guides, a stud 42 on a lever 37 to which the flap 33 is attached engages a stud 43 on the guides, which causes it to turn and lower the flap of the position shown. The camera may be applied to photographic copying, in which case the fluorescent screen may be replaced by a holder for a negative which is illuminated by lamps in a housing behind the holder. The exposure may be controlled by a time switch in circuit with the camera switch, and the time switch may effect the disengagement of the latch for the filmwinding handle. Specification 541,642 is referred to.