Patent GB-654232-A (GB)
Title: Improvements in shutter actuation in photographic cameras
IPC: G03B9/08
Filed: 1944-09-25
Abstract: 654,232. Photographic shutter actuating devices. WILLIAMSON, S. Sept. 25, 1944, No. 18297. [Class 98 (i)] A shutter actuating device comprises passive shutter operating mechanism, a flywheel supplied from a constantly running source of motive power, and means for directly clutching the shutter operating mechanism to the flywheel for one cycle of opening and closing of the shutter and then declutching it, so that the shutter is operated by energy obtained directly from the flywheel. The flywheel may be the rotating part of the source of motive power, e.g. when an electric motor is used the rotor thereof. As shown, an electric motor 13 drives through gearing 14 a flywheel 15 carried in ball bearings 16 on a shaft 5 supported at its extremities in bearings 11. The shaft 5 carries lugs 5a apertured to receive two cylindrical formations 20 on a pawl 18 having a tail piece 19, spring urged so as to raise the pawl into the path of a tooth 17 secured to the flywheel, but normally held flat against the enlarged portion of the shaft, so that the pawl lies in a recess in the shaft flush with the periphery of the shaft and clear of the tooth. The armature 26 of a solenoid 27 energized by a switch 31 is attached by an adjustable stop 28 to a pawl retainer 21 which engages an abutment 32 on the shaft 5 to hold it still and is pivoted at 23 coaxially with a pawl arm 22, the retainer 21 being urged clockwise and the arm 22 anticlockwise so that their left-hand ends contact each other by springs 25, 29. On closing the switch 31 the pawl retainer 21 is rotated anticlockwise against its spring 25, releases the abutment 32 and allows the pawl tail 19 to rise raising the pawl 18 for engagement by the tooth 17 so that the flywheel drives the shaft 5 which carries an eccentric pin 6 operating the shutter release against the action of a control spring 33. The pin 6 may be arranged to engage a slotted cross member attached to the rack of a louvretype shutter, the louvres being secured to pinions; or to engage a slotted radial extension of the blade ring of an iris diaphragm shutter. The abutment 32 having passed from the path of the pawl arm 22, this moves under its spring so that its left-hand end occupies the position previously occupied by the pawl retainer 21. As the shaft 5 completes one revolution the pawl tail passes beneath and is depressed by the pawl arm so' freeing the tooth 17 from the pawl whether the switch 31 is opened or closed, the shaft being arrested by engagement of the pawl arm and abutment 32. On opening the switch 31, the pawl retainer by virtue of its stronger spring 29 returns to its Fig. 1 position, carrying the pawl arm with it and keeping the pawl tail depressed and the shaft 5 stationary. In a modification the members 21, 22 are replaced by a forked member pivoted on the body and having its tail connected to the solenoid armature. In this arrangement each arm arrests the shaft 5 alternately after every half revolution so that the shutter is held open so long as the solenoid is energized. In an alternative construction the flywheel is mounted on the rotor shaft and carries a tyre which is frictionally engaged by a sleeve carrying a shutter operating pin and mounted on a stub shaft parallel to the flywheel shaft. This sleeve carries two diametrically disposed teeth ; one engaged by a pawl on one arm of a pivoted three-armed lever, the other arms of which are connected to a spring and a solenoid armature respectively ; and the other by a second pawl on a lever pivoted on the same pin as the threearmed lever and connected to it by a spring, its movement towards this lever being limited by a pin. The operation is similar to that of the modification referred to above.