Patent GB-650874-A (GB)
Title: Improvements in or relating to photographic shutters
IPC: G03B9/20
Filed: 1947-01-13
Abstract: 650,874. Photographic shutters. KODAK, Ltd. (Eastman Kodak Co., and Fuerst, C. C.). Jan. 13, 1947, Nos. 1133 and 26075. [A Specification was laid open to inspection under Sect. 91 of the Acts, July 14, 1947.] [Class 98 (i)] A photographic shutter of the kind having pivotally mounted shutter blades operated by a blade driving member and having a spring-operated member for tripping the latch holding the shutter set and wherein the blade driving member and the spring- operated tripping member are both set by the shutter setting means, is characterized by the latch for the blade-driving member also holding the spring-operated tripping member set and by the shutter trigger moving the latch sufficiently to release the spring-operated tripping member, but not the blade driving member which is released thereafter by the spring- operated tripping member moving the latch. As shown, the shutter case 1 which has an upstanding peripheral flange 15 slotted at 16, 17 to accommodate the setting and releasing members 7, 6, carries a mechanism plate 20, Fig. 6 and Fig. 2 (not shown), on which is rotatably mounted a blade ring 23 to which are pin-and-slot connected on their axes of symmetry symmetrical doubleended shutter blades 18 which are also pivotally mounted on the plate 20 so that anticlockwise rotation of the blade ring moves first one end of each blade out of, and then the other end into, the exposure aperture 3. The shutter is set by moving clockwise the member 7, which is secured to the blade ring 23, from the dotted to the full line position, thus tensioning the driving spring 25 attached between the casing at 27 and a pin 26 on the blade ring, and causing a pin 125 on the blade ring to move a lug 128 on a member 123 to the right-hand end of a slot 129 in a member 39, both the members 123 and 39 being pivoted at 40 on a second mechanism plate 30. The shutter is held set by a latch surface 33 on a member 32 engaging a projection mounted at 29 coaxially with a latch member 28, against which a lug 36 on it is urged by a spring 37 and which is itself latched at 31 by the member 39 and urged anticlockwise by a spring 126 arranged around the pivot 40 between a pin 116 on the member 39 and the lug 128 on the clockwise urged pivoted member 123 which is held against movement by a pin 125 on the blade ring. Since the shutter blades 18 in moving to their set position open the aperture 3, capping blades 70, 71, Fig. 6, which normally close it, are pivoted on the plate 20 at 77, 76 and pin- and-slot connected at 73 to the release lever 6 which is pivoted at 42 on the plate 30. On depressing the release 6, the capping blades open and the lever 28 is also depressed, unlatching the member 39 but not the blade ring. The member 39 which has teeth 39a meshing with a flywheel-governered train then drives the lever 28 to cause the lever 32 to release the blade ring to make the exposure. To prevent premature closure of the capping blades, the release 6 is latched in its depressed position by a lug 62 on a lever 60 pivoted on the plate 20 at 61 and spring-urged clockwise, and is released only when the edge 66 of the member 7 returns to its exposed (rest) position and strikes a lug 63 on the opposite end of the lever 60. The lever 39 is returned to its rest position, where it is again latched by the member 28, by movement of the blade ring anticlockwise releasing from the pin 125 the arm 127 of the member 123, which together with the member 39 is then rotated clockwise until the arm re-engages the pin 125 by its spring 41, carried on the pivot 40 and engaging the casing flange 15 and the lug 128 beneath the spring 126, the lug 128 having moved to the left-hand end of the slot 129 during the driven movement of the member 39, where it remains until the shutter is set again, when it moves to the position shown in Fig. 1. Slower exposures are produced by means of known retard mechanisms, such as a gear train including a gear segment 52, engaging the pin 26 on the blade ring, the amount of the retardation depending on the angle of setting of the arm 53 to the slot 50 as determined by a cam surface 91 on the exposure selecting ring 90 which is followed by a pin 54 on the segment 52. For bulb exposures, a lever 80, pivoted on the plate 20 at 42 and urged anticlockwise so that a lug 83 on it engages a surface 85 on the ring 90 and normally holds the lever inoperative by a spring 84 mounted on the pivot 61 and engaging at its other end the latch 28, is allowed to move by lug 83 entering a recess 86 in the surface 85 so that one end 82 lies in the path of the lug 34 on the lever 7, preventing the shutter from closing until the lever 6 is released, the normal lock 62 on this lever being held disengaged by a portion 88 on the ring 90. In an alternative shutter construction, Fig. 12, the casing has a flange 203 slotted at 204 for a manually operable lever 205 controlling both setting and releasing, and has a mechanism plate 215 on which is mounted a master-member operated blade ring to which are pin-and-slot connected blades 224 also pivoted on the plate 215 so that to-and-fro movement of the blade ring opens and closes the shutter. The shutter is set by moving the lever 205 clockwise to the position shown when the pin 209 on the arcuate sliding member 207 attached to the lever engages a pin 216 on the master member 210 rotating it clockwise against its spring 212 until the pin 216 which is bevelled at 218 slips beneath an arm 220 attached to the blade ring and the latch end 231 of the lever 232 pivoted at 233 and urged clockwise by a spring 234 slips behind the latch 230 on the master member, when also, due to the lug 208 on the member 207 engaging the edge 245 of the pivoted member 241, the latching edges 239, 240 on the levers 232, 241 are brought into engagement, thus holding the shutter set. On moving the lever 205 anticlockwise, the pin 238 strikes the surface 237 of the latch 232, and so without releasing the master member disengages the latch 239, 240, allowing the member 241 to be driven anticlockwise by its spring 243 to trip the latch for the master-member which by means of the pins 216, 217 engaging successively the member 220 opens and closes the shutter. For slower exposures the movement of the master member is retarded by the tail 264 of a gear segment 261 of an escapement gear train including a pallet and star wheel 271, 272 engaging a projection 265 on the master member. The subject-matter of this embodiment was contained also in the Specification laid open to inspection under Sect. 91.