Patent GB-556414-A (GB)
Title: Improvements in or relating to a photographic camera
IPC: G03B9/44
Filed: 1942-12-31
Abstract: 556,414. Photographic shutters. KODAK, Ltd. Dec. 31, 1942, No. 18610. Convention date, Jan. 30. [Class 98 (i)] The shutter of a camera comprises a pair of pivotally - mounted arcuate blades operated by springs which are both tensioned and released by the shutter trigger and move the blades with an established slot between them across the exposure aperture. The shutter is described as applied to a miniature roll-film camera, in which the objective barrel 7 is screwed into a threaded opening 8 in the body for focusing purposes, and internal walls 18 form a chamber extending from the objective to the exposure aperture 9. Curved walls 19, integral with the walls 18, together with walls 21 form arcuate slots 20 in which the arcuate shutter blades 24, 25 operate. These blades are formed with segmental side wings 26, 27 and 39, 40 respectively, which are pivoted on studs 30, 31 concentric with the centre of curvature of the blades. Hairpin operating springs 61, 62 encircle respectively pins 38, 44 on the top wings of the two blades and a common pin 60 on one arm 59 of a bell-crank lever which is carried on a pivot 55. The other arm 54 of this lever is engaged by the end of one arm 50 of a bell-crank lever pivoted at 49, Fig. 6, the other arm of which is engaged by a shutter release rod 14. The normal position of the shutter blades is that shown in Fig. 2. On depression of the rod 14 the arm 50 swings the bell-crank lever 59 in the anticlockwise direction, causing it first to stress the springs 61, 62 and then to move the pin 60 past their dead-centre positions in relation to the pins 38, 44. The spring 61 then moves the blade 24 to the left, Fig. 8, the blade 25 being held until the first blade has moved sufficiently to establish a predetermined slot S between them by the engagement of a nose 84 on the side wing 39 with the hooked end of an arm 83. This arm is pivoted on the stud 55 and is integral with an overlying arm 80 having a rounded end engaging the inner side of one of an integral pair of arcuate arms 73, 77 pivotally mounted on a stud 72. When the first blade has moved far enough to establish the slit S the pin 38 engages a shoulder 76 on the arm 73 and rocks it and the arm 77, causing the latter to rock the lever 80, 83, which releases the second blade. This moves until a lug 43 formed on it engages one of a series of shoulders 37 on an arm 34 pivoted on the wing 26 of the first blade, the two blades then moving together and the slit being maintained at constant width owing to the lug 43 being held in contact with the shoulder 37 by the spring 62. At the end of the exposure a lug 86 on the arm 34 engages a fixed lug 85, tripping the arm to disengage the second blade which then completes its movement and closes the slit. On release of the push-rod 14 the bell-crank lever 54, 59 is returned by a spring 57, and through the springs 61, 62 moves the blades, with closed slit, back to the normal position shown in Fig. 2. The exposure is varied by a dial 11 which adjusts the angular position of an arm 71 carrying the pivot 72 of the arcuate arms 73, 77, so varying the position of the shoulder 72 in the path of the stud 38 and hence the width of the slit formed when the second blade is released.