Patent GB-208773-A (GB)
Title: An electro-mechanical starting and stopping device, primarily designed for actuatingphotographic shutters, but applicable also for actuating other devices
IPC: G03B9/58
Filed: 1922-09-25
Abstract: 208,773. Lowen, C. G., Lingwood, C. P., and Pictorial Machinery, Ltd. Sept. 25, 1922. Electrically-released switches; clockwork actuation.-An electromechanical device for actuating photographic shutters, electric motors, cocks or valves, electric lights or bells, &c. designed to enable a multiplicity of exposures or other operations of equal duration to be effected, comprises a casing 1, Figs. 1 and 2, enclosing a clock 2, the seconds hand arbor 3 of which projects through the front wall of the casing and carries a counterweighted seconds hand 4 working over a dial 5 round which is a rotatable bezel 6 carrying a pointer 7 which may be locked in any set position by a device 12. The hand 4 is carried by a spring-urged sleeve 18, Fig. 8, loosely mounted on the arbor 3, and is frictionally coupled to the arbor when a disc 15, fast with the sleeve 18, is pressed against a disc 14, fast with the arbor 3, by a lever 26 actuated by a screw 28 rotated by adjustable linkage 30, 31 from a spring-urged lever 32 operable by a push. rod 50, Fig. 2. The lever carries (1) the armature 34 of an electomagnet 35, (2) the knife 36 of a switch 37 fixed to the casing 1, (3) the upper end of a spring 24 controlling a lever 23 for resetting the clock, the lever engaging at its free end under the head 22 of a rack 21 meshing with a pinion 16, Fig. 8, fast with the disc 15, (4) means of the kind described in Specification 186,132, comprising a spring 48 adapted to start the balance-wheel 49 of the clock when the lever 32 is depressed, and to arrest it when the lever returns to inoperative position, and (5) a projection 47 co-operating for example with an antinous release 46, 45 or with pneumatic mechanism, for operating the photographic shutter 44. A switch- 39 fixed to the casing is normally closed, and its spring contact blade 40 co-operates with a projection 51 on the disc 15. The parts are wired up to a battery 42 as shown in Fig. 20, and a buzzer 43 is shunted across the electromagnet 35. In operation, the bezel 6 is set and locked with the pointer 7 at the reading corresponding to the desired exposure, and the projection 8 on the bezel, or the spring 17 in the sleeve 18, automatically sets the seconds hand to this reading. according to the direction in which the bezel is rotated. The knob 50 is then depressed, taking with it the lever 32, whereupon (1) the shutter is opened, (2) the mechanism 30, 31, 28, 26, 18, 15 frictionally engages the seconds hand 4 with its arbor 3, (3) the knife 36 closes the switch 37, so energizing the electromagnet 35 and causing it to retain the lever 32, and starting the buzzer 43 (4) the lever 23 is depressed and (5) the spring 48 starts the clock. As the seconds hand moves round the dial towards zero, the pinion 16 depresses the rack 21 and, when the hand reaches zero, the projection 51 on the disc 15 displaces the blade 40 and opens the switch 39, thus stopping the buzzer and de-energizing the electromagnet 35, so that the lever 32 rises under action of its spring 33, whereupon (1) the shutter 44 closes. (2) the frictional engagement of the seconds hand with its arbor ceases, (3) the re-setting lever 23 rises, taking with it the rack 21 which, through the pinion 16. turns the freed seconds hand 4 back to the initial set position, (4) the blade 40 returns, and closes the switch 39, and (5) the spring 48 stops the clock. The apparatus is then ready for a second exposure of equal duration. For longer exposures, the seconds hand may be replaced by a minutes hand. Endwise, movement of the arbor 3 is prevented by an arm 54. Fig. 1.