Patent GB-687834-A (GB)
Title: Improvements in or relating to photographic shutters
IPC: G03B9/22
Filed: 1951-09-19
Abstract: 687,834. Photographic shutters. KODAK, Ltd. Sept. 19, 1951 [Oct. 7, 1950], No. 21951/51. Class 98 (i). In a shutter having pivotally mounted blades movable in one direction by a setting member to set the shutter and in the other direction by a spring to make an exposure upon operation of a release trigger, a blade driving ring is movable by a setting lever to tension the driving spring and is held set by a latch which upon operation of the trigger is releasable by a power-operated member upon movement of the latter, at the end of which movement it occupies a position for decelerating and finally arresting the movement of the blade ring when this has in its exposure controlling movement moved the blades past the open position. As shown, asymmetrical double-ended shutter blades 20 pivoted at 24 and controlled by pins 28 carried by the blade ring 26 and engaging. in slots in the blades which are reinforced about the slot and pivot are provided to produce a greater overlap in the rest position than in the set position. By moving a roughly semicircular lever 38 pivoted at 39 near one end of the diameter from position to position II against the action of a return spring 25, a projection 141 on the lever engaging a pin 34 on the blade ring moves the latter, tensioning the driving spring 35, to a position where the blade ring is held set (Fig. 6), due to the engagement of a pin 30 thereon by the nose 41 of a latch lever 42 pivoted at 43 and spring-urged anticlockwise, the lever 38 returning to the position I on letting it go. During the setting movement the blades open and close but the exposure aperture is maintained closed by two oppositely disposed pivoted sickle-shaped cover blades (not shown). Simultaneously with the setting of the blade ring, a pin 31 on the ring rotates anticlockwise an arm 70 which is pivotally mounted on the manual trigger 61 and spring-urged so as normally to extend radially of the shutter, as shown, and prevent operation of the trigger until the shutter has been set. A pin 30 on the blade ring also tensions the driving spring 55 for a member 48 which trips the latch lever 42, said spring being connected between a fixed pin on the member 48 and the pin 30. The power-operated release member 48, which is pivoted at 54 and geared to a governing retard train 59, 60, is held with its driving spring tensioned by a sub-trigger 47, which is pivoted at 49 and spring-urged anticlockwise and has an arm 51 which blocks the path of an arm 56 on the member 48. On depressing the manual trigger, which is pivoted also at 49, against its return spring, an edge 67 on the lever engages a lug 52 on the sub-trigger so that the latter moves clockwise, whereby a pin 117 thereon engaging in slots in each of the two cover blades (not shown) moves these blades to clear the exposure aperture and the arm 51 moves clear of the arm 56 of the power-driven member 48, which in turn trips the latch 41 and allows the blade ring to move anticlockwise and effect an exposure. The power-driven member in its tripping movement moves into a position in which towards the end of the exposure its cammed edge 57 engages the pin 30 on the blade ring, thereby slowing down the blade ring while the blades are overlapping. For a faster exposure, an additional spring 94 between a pivoted lever 95 and a pivoted arm 91 assists the blade ring movement by causing the arm 91 to bear in the set position of the shutter on a pin 100 on the blade ring, the spring 94 being initially tensioned by an anticlockwise setting movement of the lever 95. Slower exposures are produced by a retard gearcontrolled pivoted sector 33 having a nose 75 extending into the path of a block 32 on the blade ring, one set of exposures being made without the pallet 84 in train by varying the initial position of the sector and a second slower set being made with the same sector settings and with the pallet in train. The exposure time is selected by a ring (not shown) bearing cams controlling the settings of the lever 95, sector 33, and pallet 84 by engaging projections 97, 85, and 89 thereon respectively. A bulb exposure may be made when an enlargement of a peripheral cam track 114 on the exposure setting ring allows a lug 113 on a lever 66 which is pivoted at 54 to move inwardly under spring action so as to follow the trigger 61, whereby on operation of the trigger, a shoulder 110 on the lever 66 arrests the blade ring pin 31 holding the shutter open until the trigger is released. The power-operated tripping member 48 also carries a contact pin 105 which it moves against a contact 106 of a flashlight circuit carried on a pivoted insulated lever 204, the position of the contact 106 being determined by the engagement of a pin 201 on the lever 204 with a control cam on a setting ring (not shown) to accommodate lamps of different lags.