GB402890A - Improvements in or relating to cameras for use on aircraft - Google Patents

Abstract

402,890. Photographic cameras; gyroscopic apparatus. BOWEN, I., Air Ministry, Kingsway, London. Aug. 10, 1932, No. 22389. [Classes 97 (iii) and 98 (i).] A camera and a gyroscopic vertical indicator are combined so that the images of an index mark on the gyroscopic system and a datum mark fixed relatively to the camera which show the relative tilt of the indicator and the camera, are recorded simultaneously with the image of the ground when the camera is operated. As shown, the gyroscope rotor 1 is mounted in gimbals 3, 5 in a casing 7 relatively to which it is constrained by an electro-magnet 8 which produces eddy currents in a metal disc 9 on the rotor spindle and tends thereby to maintain the rotor spindle erect to the casing. Alternatively the rotor may be constrained relatively to the casing by means of a spring. The casing 7 is secured to the body 10 of the camera, of which 11 is the film box and 12 the lens cone, by means of an intermediate casing 7x containing an optical projection system comprising a prism or mirror 13, a lens 14 and a prism or mirror 15 disposed in a tube 16 secured in the casing 7x. Alternatively the casing 7 may be secured to the film magazine or the lens cone of the camera. A disc 20 bearing an index mark is mounted on the gimbal ring 3 in alignment with the rotor axis 2, and the optical system 13, 14, 15 projects an image of the index mark on to the film. An image of the graticule 21 is also projected on to the film. An electric lamp bulb 22 illuminates the disc 20. The camera main blind 23 and the capping blind 24 or their release mechanism are arranged to close the lamp circuit to illuminate the disc 20 at the time of exposure. Alternatively, the optical system 13, 14, 15 may be arranged so that the index mark on the gyroscopic vertical indicator and the graticule fixed relatively to the camera are photographed on a separate film or plate from that on which the ground is photographed. Instead of controlling the photographing of the index mark and the graticule by means of the camera blind or shutter it may be controlled by a blind or shutter working simultaneously with but separate from the camera blind or shutter, or by the lamp 22. A large graticule concentric with the optical axis 25 of the camera may be provided on the glass plate 26 against which the film is pressed. In a modification a gyroscope rotor pendulously controlled may be used as a pitch and roll indicator.