GB588776A - Improvements in or relating to photographic shutters - Google Patents

Abstract

588,776. Photographic shutters. KODAK, Ltd. March 5, 1945, No. 5492. Convention date, March 28, 1944. [Class 98 (i)] A pair of blade-operating rings in a photographic shutter are movable in opposite directions by means of a rocker arm so that for one exposure one blade ring is driven and for another exposure the other blade is driven, both in the same direction, the driven blade ring driving the other ring in the opposite direction through to rocker arm to effect an exposure. The shutter blades 9 are pivoted at 10 to an outer blade ring 8 and carry pins 11 engaging slots 12 in an inner blade ring 7. A rocker arm 13 has slotted ends 15, 16 engaging pins 17, 18 on the blade rings. The master member comprises a ring 19 and a setting handle 20 with a constraining spring 23. The ring is retained in set position by a latch element 27 with a handle 29 extending through the shutter casing, the latch being released against the pressure of a spring 31. When the lever 20 is moved to setting position, a selector cam 32 carried by a frictionally held ratchet 33 pivoted on the handle is moved by a spring pawl 34. A roller 54 presses against this cam and is carried by a sliding driver 50 (Fig. 7) which is slotted to slide on the stud supporting the cam. A spring 55 maintains the roller and cam in . contact, each part rotation of the cam displacing the position of the driver 50 and of a driving pin 49 mounted on its underside. The ' cam 32 has two sets of surfaces 60, 61, one a greater distance from the stud 39 than the other. The pin 49 in its two extreme positions corresponding to engagement of roller 54 with the two sets of surfaces 60, 61 engages projections 47, 48 on either of the blade rings 7, 8, its position being changed with each exposure by the action of the pawl 34 in rotating the cam. When the master member is released, the pin 49 engages the appropriate blade ring and rotates the double-ended blades. In a modification (not shown), the pins which coact with the slots of the rocker arm 13 are extended upwardly and are coacted in turn by one or other of two pins on the driver, the rocker arm in this case being located close to and in the path of the driver arm of the master member.