Patent GB-790831-A (GB)
Title: Improvements in or relating to photographic apparatus
Inventor: FOSTER CLAUD
IPC: G03B39/02
Filed: 1953-09-09
Abstract: 790,831. Photographic cameras. BARR & STROUD, Ltd. Aug. 10, 1954 [Sept. 9, 1953], No. 24891/53. Classes 97(1) and 98(1) In a high speed photographic camera, in which a rotatory reflecting means arranged at the centre of curvature of an arcuate film path sweeps a beam of light around the path and projects a series of images on to the film 49, film feeding and supporting mechanism comprises an arcuate film supporting drum 54, a backing band 60, and a series of rollers 65. The rollers 65 may be moved outwards from the drum 54 to assist in feeding the film and inwards so that the film may rest on the drum during exposure. As shown levers 67 supporting rollers 65 are pivoted to the drum 54 and interconnected by links 68 so that all the rollers can be simultaneously moved to the outward position in which the film 49 is carried on the middle section 65b of the rollers 65, and the band 60 on outer sections 65a. As shown in Fig. 1 the reflecting mirror may be a plane mirror 25 rotating about an axis inclined to its surface and, an erecting prism 22 rotating at half the angular speed of the mirror may be included in the optical system. In the form shown in the other Figures the optical system is substantially the same as described in Specification 790,832, the film parts 49a b and c being arranged as shown in Fig. 15. The bands 59, 60 are in the form of two steel ribbons and are provided for threading the film 49 one and a half times around the drum 54 starting at the unexposed film. cassette 57 and ending at the exposed film cassette 58. Bands 59 and 60 art first wound into drums 61 and 63 and the' leading end of the unexposed film is clipped to band 59 near drum 61. Band 59 is then wound into drum 62 drawing the film around the underside of the drum. The leading end is then passed over rollers 75 and clipped to band 60 near drum 63, which is wound into drum 64 thus drawing the film 49 up to the cassette 58. Levers 67 are then actuated to move the rollers 65 into drum 54 and, after the film has been exposed through apertures 55 in drum 54, the film is changed by winding cassette 58. Sprocket 79 drives an exposure counter. A telescope 89 is provided for focusing the camera, and light from lens 40, (Fig. 11, not shown), is directed to it through lenses 90 by means of a prism which is mounted on a plate 91 and may be swung into the operative position bv lever 92 and Bowden cable 93. Lens 40 mav be replaced by a small aperture lens. and beam-splitter. The camera is carried on a four-wheeled bogey 84 having a three point support, and it can be angularly adjusted in azimuth about pivotal support 87. The shutter mechanism and control circuit for the camera is substantially the same as that described in Specification 790,833. The light from lamp 111 passes periodically through aligned slits in occulting discs 96, 97 (not shown) and, is then reflected on to a photo-electric cell 110 (Fig. 19b). The start of the exposure is indicated when a signal from the photocell is immediately followed by a signal caused by the closure of contacts 113 by push rod 108. Contacts 113 are actuated by push rod 108 before it completes its travel and after it has opened capping shutter 98.