Patent GB-790833-A (GB)
Title: Improvements in or relating to photographic apparatus
Inventor: FOSTER CLAUD
IPC: G03B9/08
Filed: 1953-09-09
Abstract: 790.833. Photographic cameras. BARR & STROUD, Ltd. Aug. 10. 1954 [Sept. 9. 1953], No. 24893/53. Classes 97(1) and 98(1) In a high speed photographic camera in which at least one rapidly rotating reflector sweeps a beam of light round at least one arc of lenses which produce images on a stationary arcuate photographic film. and a shutter is controlled automatically to prevent double exposure, the axis of the arc of the film lies in the plane of the reflector. Preferably, the shutter comprises two superposed co-axial occulting shutter discs 96, 97 rotating in the same sense but at different speeds and having eccentric light apertures which periodically coincide. The form of the camera is substantially the same as that disclosed in Specification 790,832 and continuously rotating exposure discs 95 open at several times the frequency at which the apertures of discs 96, 97 coincide with the exposure aperture 97a. The discs 95 thus ensure a sufficiently rapid exposure time between the separation of their trailing edges (Fig. 16a) and the coming together of their leading edges (Fig. 16b) to prevent double exiposure, while discs 96, 97 provide sufficient time for a capping shutter 98 to close and thus prevent multiple exposure. The capping shutter is opened just before an exposure is about to commence by an upward thrust exerted on lever 105 and rod 108 by the armature of solenoid 102 so that roller 106 enters groove 107 in cam 99 which rotates at the same speed as the slower occulting disc 97. Solenoid 102 is energized by push-button 127 or remote control push-button 128 and the armature opens the blades 98 at the commencement of its travel; by a further movement it opens contacts 109 to de-energize solenoid 102 and closes contacts to signal the commencement of the exposure. As the roller 106 leaves the other end of groove 107, the lever 105 is thus able to return to its original position and the shutter 98 is accordingly closed as soon as the exposure has been made. Relay 130 is energized directly by push-buttons 127 or 128 and the closure of contacts 130a, b and c energizes relay 129. retains relay 130 and energizes solenoid 102 respectively. Contacts 109 cut out relay 130 thus de-energizing solenoid 102 by opening contacts 130c. Contacts 129b retain relay 129 with contacts 129a open as long as push-buttons 127 or 128 remain on and relay 130 cannot therefore be re-energized until pushbuttons 127 and 128 are opened. Slits may be provided in discs 96, 97 so that light may pass through them and operate a photo-electric cell to indicate the moment at which the exposure commenced. The reflector may be driven by a variable' speed motor energized by a motor-alternator set supplied with direct current. The phase voltage output of the alternator is adjusted to run the motor at the desired speed. For flash exposures, the drive to the shutter discs is declutched from the drive to the reflector, the shutter discs are set in their fully open position and the capping shutter is opened by solenoid 117 through switch 131 instead of by the normal exposure controlling solenoid 102, the signal produced by the exposure signalling contacts being used to set off flash illumination.