Patent GB-684502-A (GB)
Title: Photographic pivoted blade shutter having a contact device for flashlight exposure
IPC: G03B9/70
Filed: 1950-03-23
Abstract: 684,502. Photographic shutters incorporating self-timers and flashlight synchronizers. GAUTHIER GES., A. March 23, 1950 [Jan. 30, 1950], No. 7348/50. Class 98 (i). A pivoted blade shutter having an electrical contact device for flashlight exposures includes a retard mechanism which retards the opening of the shutter relative to the actuation of the shutter release, and which consists of two relatively movable parts, one of which has a source of power, and a manually-operable member for coupling and uncoupling said two parts, so that with the aid of the whole retard mechanism delayedaction exposures can be effected whereas when the parts are uncoupled, the part having the source of power can be used to synchronize flash-lamps with the shutter for all kinds of lamps and exposure times, and the shutter is also provided with a single lever for setting the retard mechanism for both delayed-action exposures and for flashlight synchronized exposures, said lever by varying the extent of its setting movement adjusting the escapement timings to effect synchronization with different lamps. as shown, the master member is set by anti-clockwise movement of an integral lever 4 and is latched by a bell-crank lever 22 engaging a nose 4p on it so that on depressing the shutter release 23 the latch is released and the master member drives by means of a link 4a a pin 2a on the blade ring 2. For delayed action exposures, the lever 26 is moved clockwise to tension the retard mechanism comprising a sector gear on the lever, gears 31, 28, 32, 29, 33, star-wheel 30, pallet 34, and driving- spring 26<SP>1</SP>, the mechanism being held set either by a pin of a leaf-spring on the shutter casing engaging in the teeth of one of the gears of the train, in which case the retard mechanism mounting plates are pivoted in the casing or by a pin on the blade ring engaging one of the gears, in which case the retard mechanism mounting plates are rigidly fixed in the shutter casing. On depressing the release 23 the blade ring moves and releases the retard train, whereafter a lug 5 on the blade ring engages a concentric circuate cam on the lever 26 so delaying opening of the shutter until the retard train has run down. Alternatively a three-armed lever 38 may be mounted on the pivot of the lever 26 with one arm 38<SP>2</SP> spring-urged against a pinion 32 of the train and on movement of the blade ring the lug 5 first strikes the arm 38<SP>1</SP> to release the train just prior to the lug striking the cam on the lever 26. If it is desired to employ a flashlamp with a delayed-action exposure, approximate synchronization is achieved by an anticlockwise urged lever 11, which is freed by movement of the pin 2a on the blade ring, engaging as the shutter opens an insulated contact 12 of the lamp circuit, one side of which is connected to the shutter casing. For accurate synchronization of instantaneous exposure with flashlamps of finite lag, a pointer 401 on a ring 40 is moved from the mark 41 to mark 42 when the lug 40<SP>3</SP> on the ring moves the bridge 45 pivoted at 46 carrying the star-wheel and pallet to disengage them from the retard train and a lug 40<SP>2</SP> on the ring uncovers an opening in the shutter casing through which the tail of an anticlockwise urged lever 43 may project when the blade ring moves its pin 44 to allow this lever to pivot and close the lamp circuit by engaging the insulated contact 12. The lever 11 also engages this contact as stated above but not until after the lamp circuit has already been closed and so has no further effect. The extent of the setting of the lever 26 now determines the delay between the closing of the lamp circuit by the lever 43 and the opening of the shutter. In a modification, Fig. 6 (not shown), the bridge 45 is manually movable and is connected by a pivoted link to a contactspring carried on but insulated from a pivoted lever and connected to the insulated flash-lamp terminal. The contact-spring is held clear of the path of a block on the shutter blade ring when the star-wheel and pallet are engaged with the retard gear train to effect delayed action exposures and is moved into said path when the star-wheel and pallet are disengaged to effect synchronized flash-light exposures.