Patent GB-557050-A (GB)
Title: Improvements in or relating to photographic cameras
IPC: G03B42/02
Filed: 1942-09-14
Abstract: 557,050. Roll-film cameras. GENERAL ELECTRIC CO., Ltd., and CALDWELL, J. T. Sept. 14, 1942, No. 12946. [Class 98 (i)] A camera comprises a motor-driven film-feed sprocket, a control switch which in one position causes operation of means controlling the exposure, and in another causes energization of the motor and operation of an electromagnetic relay which withdraws an abutment member from engagement with a stop member rotated by the motor, and a contactor operated by the feed sprocket which subsequently de-energizes the relay so that the abutment member returns to its operative position and at the end of the film feeding operation engages the stop, this engagement serving to stop the motor. In the apparatus shown, which is intended for photographing X-ray screen images, a motor 23 drives the film sprocket 21 through a resilient coupling 33, unidirectional coil-spring coupling 35 and gears 34, 36, 37. In one position of the control switch contacts K2, K7 are closed, so controlling the operation of the X-ray source through the terminal connections T1, T2. When the switch moves to its other position the contacts K1 are closed, energizing a holding relay W1 which closes the contacts K3, so energizing the relay W2. The latter rocks the armature 30, causing it to close contacts K4 to energize the motor and to withdraw an abutment member 27 from one of the diametrically opposite pair of notches in a disc 26 rigid with the gear 34. Winding of the film then occurs, during the course of which a notch in a disc 25 rotating with the gear 34 comes opposite an abutment on a contactor K5, causing momentary opening of the contacts, which de-energizes the holding relay Wl and hence the relay W2. The motor circuit contacts K4 are however held closed until, at the end of the film-winding operation, the abutment 27 falls into the other notch of the disc 26, so allowing the armature 30 to return to the position of rest shown. The film may be wound on two frames after every series of ten or other desired number of exposures by the closure at this time of contacts K8, in parallel with the contacts K5, by a projection 41 on a disc 40 driven at an appropriate speed, thus maintaining energization of the relay W1 when the contacts K5 open. The film may be continuously wound by closing a switch K6, which energizes the relay W2. It may be fed manually by reciprocating a lever 43 through slightly over a half revolution, so driving the gear 36 through a one-way spring clutch 44. At the end of the idle stroke a projection 45 on the lever lifts the abutment 27, so freeing the disc 26 for movement during the driving stroke, which is terminated by the abutment falling into the other slot. The take-up spool is driven through a one-way resilient spring clutch through an idler gear 47 carried by a spring-urged lever 48. During normal operation, the gear is urged into mesh with the wheels 37, 46 and causes the lever 48 to maintain contacts K10 in the exposure circuit closed. Should, however, the film not be under the requisite tension the lever moves under the action of a spring 50 and allows the contacts K10 to open, preventing exposure. The camera, Fig. 1, is provided at the front with a door 60 which is held closed by a spring catch 62 until the latter is released by the attachment of the camera to a light-tight hood 12, when the door falls under the action of gravity or a spring, and in so doing closes contacts 63 in the exposure circuit. Other contacts 66 in this circuit are closed only when film is present in the gate, through plungers 64 which bear on the film. Holders 17, 18 for the film supply and take-up spools are slidably attached by tongue and groove connections to the camera body, and are held in place by a door 16. Before detaching the holder 18 for processing of the film, the film is cut by releasing a catch 71 which holds a guillotine blade 67 against the action of a spring 70.