Patent GB-724581-A (GB)
Title: Improvements in or relating to photographic shutters
IPC: G03B9/10
Filed: 1953-04-01
Abstract: 724,581. Photographic shutters. KODAK, Ltd. April 1, 1953 [April 2, 1952], No. 9041/53. Class 98 (1). A shutter in which a pivotallymounted shutter blade is connected by a spring with a pivotally-mounted cover blade normally disposed to cover the shutter aperture, the construction being such that on release movement of the shutter trigger the cover blade is moved clear of the shutter aperture and the shutter blade is operated by said spring to make an exposure, the cover blade being returned after the exposure to cover the aperture before the shutter blade returns to rest, is provided with a latch for normally holding the cover blade across the shutter aperture, a driving spring for the cover blade, a setting member for tensioning said cover blade driving spring and which is movable against the action of a return spring to a set position in which it is held by latching means, said cover blade latch being released by operation of the shutter trigger which upon return to its rest position releases, the latching means for the setting member so that this is moved by its return spring to its rest position and simultaneously moves the cover blade to cover the shutter aperture in which position it is held by the latch therefor. As shown, the shutter is set by moving the arm 47 of a plate 49 pivoted at 32 anticlockwise against a return spring 62 to a position in which a lug 51 on the plate 49 is latched by a nose 60<SP>1</SP> on a clockwise-urged lever 60 thereby tensioning a spring 43 between a notch 45<SP>1</SP> in a step in the plate and a pin 45 on a cover blade 31 also pivoted at 32 and which is latched in a position covering the exposure aperture 17 by a nose 35 on a clockwise-urged three-armed lever 135 pivoted at 36 engaging a lug 34. On moving anticlockwise the shutter trigger 39 also pivoted at 32, a shoulder 40 thereon engages a lug 38 on the lever 135 and so trips the latch for the blade 31 which moves under action of the tensioned spring 43 clear of the exposure aperture which is then uncovered since the shutter blade 18 is positioned with its aperture 19 over it. The movement of the blade 31 causes a lug 33 on it to engage an arm 65 on the lever 60 to trip the latch for the plate 49 which is then latched by a nose 64 on a similar lever 57 and simultaneously tensions a hairpin spring 28, weaker than the spring 43, between the blades 31, 18, so that when the dead-centre position is reached the blade 18 rotates clockwise on its pivot 20 to close the shutter. To avoid rebound, the blade 18 is decelerated by a rounded nose on an arm 37 of the lever 135 engaging a cam flange 23 on the blade the clockwise movement of which is finally arrested by a projection 21 on it engaging a stop 14. On releasing the trigger, it is spring-returned clockwise and a projection 67 on it engages a lug 66 to trip the latch 64 for the plate 49 which is returned by the spring 62 which is stronger than either of the springs 43, 28. On the return movement, an arm 50 on the plate engages a lug 78 on the blade 31 and returns it to cover the aperture 17 closed by the blade 18, and in so doing again tensions the hairpin spring 28 to rotate anticlockwise the blade 18 back to the rest position shown. An exposure may be made either as described above or at the cost of increased camera shake by merely operating the trigger 39 since this has a riser 71 which may engage in a notch 54 in the setting member 49 and so cause setting to be followed immediately by release. If a shutter with a faster exposure is required, the aperture 19 does not initially overlie the exposure aperture so that - the shutter is both opened and closed by the blade 18, the blade 31 serving only as a cover blade. By moving a lever 11 anticlockwise so that an abutment 70 is brought into the path of the projection 21 on the blade 18, bulb exposures may be made. An insulated spring -contact 81 having a depending flange 82 formng part of a flashlamp synchronizing switch makes a wiping contact with the blade 31 before the aperture 17 is opened. Specification 634,679 is referred to.