Patent GB-128609-A (GB)
Title: Improvements in or relating to Aerial Photography.
Inventor: BROCK ARTHUR
IPC: G03B19/02
Filed: 1917-01-03
Abstract: 128,609. Brock, A. Jan. 3, 1917. Cameras for roll-films with connected action, between shutter and changing- mechanism; aeronautical apparatus.- A camera for taking a series of photographs from aircraft has an intermittently-operating motor for operating the film-feeding mechanism and the shutter, and timing-mechanism for starting the motor at regular intervals. The timing-mechanism is regulated by means operable from the pilot's seat. The motor for operating the film feed and shutter comprises four spring drums J<1> - - J<4> Fig. 6, the drum J' carrying a spur-wheel j<14> for driving the film mechanism and a second spur-wheel j<15> engaging the spur-wheel j<1>, Fig, 2, of the timing-mechanism, by which the tension of the spring j<19> is maintained. The film-winding mechanism comprises spur-wheels M, F<1>, Fig. 5, which drive the winding-roll F through a friction clutch F<2>, F<3>,Fig. 6. Engaging with the pinion F<1> is a spur-wheel L' engaging gearing M<2>, E<1> which drives a measuring-drum E for measuring the required amount of film for each exposure, and also drives the roller blind mechanism. The spurwheel L<1> carries on its axle ratchetwheels L which are released in turn by pawls K<2>, the timing of which is controlled by the timing-gear. The timing-gear comprises a spring drum j<19> wound by means of a handle j<31> driving an escapement-wheel j<1> engaged by an anchor escapement j<9> attached to an adjustable pendulum j<11>, j<12>. The axle of the spring drum j<18> carries cams j<20> which engage the levers K by which the pawls K<2> are moved. In the form shown in Figs. 2 and 5, the adjustable pendulum comprises a lever j<11> carrying a pin j<13> engaging a slot in the heavy disk j<12> mounted on the pivoted arm j<16>. The timing is regulated by altering the distance of the disk j<12> from the lever j<11> by means of a cam j<24> operated by a worm and worm-wheel. The worm may be rotated through a flexible shaft by means of a handle on the aeroplane. In the form shown in Fig. 10, the adjustable pendulum comprises a lever j<110> a slot in which engages a pin carried by the lever j<120> carrying weights j<123>, the position of which is varied by means of a right and left handed screw j<124>. The shutter arrangement comprises a roller-blind shutter G moving in the focal plane, and a safety shutter R opened immediately before and closed immediately after an exposure is made. The roller-blind shutter is wound up by means of gearing M<2>, E', M<3> - - M‹ from the spur-wheel L, and is held against return by means of a ratchet-wheel and pawl I<4>. When sufficient film is wound and the shutter set, the cam j<21> on the timing-gear engages the lever N, which trips the pawl I<4> and releases the shutter. Immediately before the release of the shutter G, the safety shutter R is opened by means of a cam L<3> engaging a lever R bearing against the short lever R<2>. For use on aircraft, the apparatus is suspended in gimbals provided with dash-ports, as described in Specification 128,593. In order to prevent the winding of the film from the supply to the take-up spool from disturbing the centre of gravity of the apparatus, the counterweight S<7>, Fig. 9, is mounted on a lever S<5> connected through link-work to a roller S<2> kept in contact with the film on the roll C by a spring S'.