Patent GB-552923-A (GB)
Title: Improvements in or relating to radiographic camera systems
IPC: G03B42/02
Filed: 1941-09-23
Abstract: 552,923. Radiographic apparatus. WATKINSON, E. J. W. Sept. 23, 1941, No. 12327. [Class 98 (i)] Radiographic apparatus comprises in combination an X-ray tube with a fluorescent screen, a film camera for photographing the image on the screen, a spring or other motor which is set in operation by a press button and automatically feeds the film and subsequently renders the tube operative, a holder for an index card which is photographed together with the image on the screen, means for illuminating the card, a switch in the actuating circuit of the camera adapted to be operated by the card, and a press button or like switch for initiating the operation of the camera. The camera shown is provided with a spring driving motor c which is normally held out of action by a brake pad mounted on a pivoted arm y. Closure of a starting switch energizes solenoids 4, which attract an armature 3 on the arm y and rock the arm clockwise, so releasing the brake from the motor. The arm is locked in this position by a pin v on an arm w moving along a slot in a locking lever o and becoming engaged in an angular extension at the end of the slot. The motor drives a snindle e through a single revolution, during the first half of which a film sprocket 30, Figs. 4 and 5, is driven to feed the film. The driving means comprises an axially-slidable clutch element 26 having two holes 27 in either of which a spring pressed pin 28 carried by the sprocket may engage. Engagement and disengagement of the clutch is caused by a pin 33 which rides over a fixed cam surface 34 and swings a stirrup arm 231 having pins engaging a groove 25 in a collar on the clutch member 26. A gate member 44 carried by spring-urged parallel links 40, 41 holds the film during exposure against a rear gate member 31, Fig. 4, but during movement of the film is held away by a swinging movement of the links produced by an arm 38 when it is engaged by a stepped peripheral part 36 of a disc 35 carried by the spindle e. A sprocket s loosely mounted on a shaft i is connected by a chain to a sprocket g on the spindle e, and drives a sprocket 5 connected by a chain to a sprocket 21 on a spindle 7 having dogs 9 which engage and rotate the driving pin 10 of the film take-up spool 11. A slipping clutch 6 between the sprockets s and 5 allows the former to continue rotating when the film is held during exposure. A disc k rigid with the sprocket s has a projection n which, at the commencement of the second half rotation of the spindle e, engages a lever q to close relay contacts causing the operation of the X-ray tube for a preset time to effect the exposure. Subsequently a pin m on the disc k engages the lever o and rocks it to unlatch the arm w which then, together with the lever y, returns to the position shown in Fig. 1, so stopping the motor. The pin m also moves a feed-wheel p the teeth of which engage apertures 62 in a drum 58, so rotating it step-by-step to bring translucent exposure-registering indications 57 successively opposite an aperture 60, where they are illuminated by a lamp. At one corner of the fluorescent screen is a frame for an index card carrying a switch which is closed by the insertion of a card. This switch, a lamp which illuminates the card, and an indicator lamp 53, are connected in series to a current supply, and across the lamp 53 are connected in series the starting switch, the solenoids 4, and contacts 51 which are closed by the edge of the film engaging them. It is thus necessary for an index card to be in position, the lamp which illuminates it to be lit, and film to be in position in the camera before the starting circuit can be completed. The film magazine, Fig. 4, comprises spool chambers 16, 17, film sprocket 30, and rear eate member 31, all carried by a plate 14 which closes an aperture in the camera wall through which they are inserted. A pivoted latch 45 retains the plate In position, and when turned to release the plate operates linkage which withdraws the front gate member 44 from the film.