Patent GB-456225-A (GB)
Title: Improvements in and relating to cinematograph cameras
IPC: G03B21/32
Filed: 1935-05-29
Abstract: 456,225. Kinematograph apparatus. WILLIAMSON, C. M., Cascade Works, Litchfield Gardens, Willesden Green, London. May 29, 1935, Nos. 15645/35 and 15256/36. [Class 97 (i)] In a motor-driven camera operative while a trigger is held, means is provided to expose one additional film frame after the trigger has been released and the movement cycle then in progress has been completed; the camera may be attached to a gun and the additional exposure may be of a watch or other instrument. The camera mechanism may be driven by a motor 6 geared to a shaft 7 carrying a drum 41 having an aperture 42 in its periphery and containing a loose stop member 59 urged by a spring 61 to rotate into a position in which its front face engages a projection 60 fixed within the drum. When the mechanism is still, the member 59 is engaged, as shown in Fig. 2a, by a pin 43 on an arm 44 secured to a shaft 45, and the rear face of the member 59 is engaged by the projection 60. When exposure is to begin, the arm 44 is rocked by the action of a solenoid 54 on an arm 48 fixed to the shaft 45, and the pin 43 is moved through the aperture 42 to release the drum &c. ; the solenoid 54 and motor 6 are wired in parallel. The spring 61 then rotates the member 59 relatively to the rotating drum so that its front face engages the projection 50. When exposure is to stop, the circuits of the motor and solenoid are broken by release of the trigger, and the spring 55 pulls on the arm 48 to cause the pin 43 to enter the aperture 42 when, on the completion of the movement cycle, it comes into position. The momentum of the motor armature causes the drum to continue rotating until the projection 60, after substantially one revolution of the drum, again engages the rear face of the member 59; the mechanism is so designed that this rotation of the drum produces one additional exposure. The additional exposure may be effected through the back of the film, the light beam to the front of the film being cut off by a shutter 56 which is rocked by an arm 50 fixed on the shaft 45. This exposure may be of a watch 63 held in a sliding panel 64 on one side wall of the camera, and is effected by an objective and reflecting prism in a cell 68, and by lamps 62 illuminating the watch and controlled by switch contacts 57 caused to engage by a spring-pressed arm 51, 52, loose on the shaft 45, and riding on a cam 58 before and after the exposure ; the arm 52 is held so as to be ineffective throughout the preceding exposures by a stop on an arm 49 fixed on the shaft 45. A friction clutch 70 may be interposed between the motor 6 and shaft 7, if the energy of the armature is great, to reduce shock produced by the sudden engagements of the projection 60 and member 59 ; alternatively, if the energy is small, motor contacts 57a may be closed simultaneously with the lamp contacts. The camera mechanism may be carried by a plate 1 having upper and lower flanges 2 slidable in a casing 3, and held by a screw 10 manipulated by a knob 11. The shaft 7 drives, through helical gears 12, a double-pin wheel 13 actuating a Maltese cross 14 on a spring-mounted shaft carrying one half of a dog clutch mating with a clutch member on a sprocket shaft in a separate film magazine. It also drives an intermittent shutter 23 through a gear 25 and teeth on the shutter rim ; a double-winged member 26 may be rotatable about the shutter axis to vary the size of the shutter aperture. Rotation of the member 26 is effected by axial movement of a sleeve 29 having a pin engaging a helical slot in a sleeve 27 to which the shutter is secured, and a pin 29a engaging the member 26. The sleeve 29 is movable through a push rod by a face cam on an externally adjustable ring 32 or by a lever remotely controlled through a Bowden wire. In a modification, the sleeve may be movable into either of two positions by means of a lever and solenoid. A switch blade 37permanently engaging a feed stud 39 may be moved into engagement with any of three studs 38, by rotation of an external ring 40, so as to vary the resistance in the motor circuit. An interchangeable graticule 71 may slide in a holder 72 in front of the gate, heaters 74 controlled by a thermostat 75 may be provided on the plate 1, and the wiring may be led to a plug fitting 73. The apparatus may be operated and controlled by compressed air. The film may be carried by spools in a magazine containing the gate and intermittent sprocket, the take-up spool being driven from the sprocket shaft by a belt or by a gear train and friction clutch ; the magazine is inserted in the casing behind the lens 9, shutters &c. by way of a hinged lid 5. According to the first Provisional Specification, a centrifugal governor is geared to the main shaft, the shutter 56 is operated through a toothed sector, and the cam producing the closure of the lamp contacts is within the drum.