GB537068A - Improvements in or relating to focal plane shutters - Google Patents

Abstract

537,068. Photographic shutters. KODAK, Ltd. May 8, 1940, No. 8277. Convention ate, Aug. 3, 1939. [Class 98 (i)] A focal-plane shutter of the type having two curtains so arranged that, on release, one moves relatively to the other to form the exposure slit, whereupon both move together to make the exposure, is provided with a speed-setting dial coupled to the shutter mechanism so as to vary the width of the slit and with manuallyoperable means carried externally on the camera which is coupled to the setting dial to adjust it, and is uncoupled from it by means operating during the first part of the movement of the release trigger. The invention is described as applied to a shutter of the kind described in Specification 529,297, tapes 37 from the first curtain being wound on rollers 38 and the second curtain 32 being wound on a roller 39. The shutter is wound by rotating a gear 41 by a mechanism which may be of the type described in Specification 513,738. The speed-setting knob 6 is mounted on a shaft 8 passing through a slot 9 in the camera wall and carried by a pivoted arm 10, the shaft 8 carrying also a gear 14 which engages a gear 15 carried by the speed dial 16, when the parts are in the position shown, so that rotation of the knob 6 adjusts the dial. The arm 10 is latched in this position by a lug 30 on it which is engaged by a lug 29 on a pivoted arm 20. Depression of the release button 28 swings a bell-crank lever 26 anti-clockwise which, through a connecting- rod 25, moves the arm 20 clockwise, the initial movement unlatching the arm 20 which is then given a small movement by a spring 12 to withdraw the gear 14 from engagement with the gear 15 and to move the knob 6 so that its edge protrudes through an open portion of the side wall of a recess 5 in which it is mounted. Further movement of the arm 20 causes a lug 22 on it to engage a pawl 23 to release the first curtain, which as it runs down rotates the gears 55, 55<SP>2</SP>, 55<SP>1</SP>, 48, the dial 16 and a dial plate 42 which it carries beneath it. Movement is transmitted from the gear 48 to the plate 42 by a spring clutch 46, one arm 45 of which engages in radial notches in the plate, but allows the dial to be rotated to adjust the speed after winding the shutter. After a degree of movement determined by the initial setting of the speed dial, a pin 49 projecting downwardly from the dial plate strikes a lug 50 on an arm 51, causing it to rock the shaft 52 on which it is mounted, so that a pawl 53 on the same shaft is disengaged from a single-toothed ratchet 54 secured to the roller 39 of the second curtain, which is thus released. At the same time the pawl 53, which before its movement engages the tail of a pawl 56 on the ratchet disc 54, releases this second pawl, which then engages a tooth of a ratchet 61 secured to roller 38, thus latching the rollers 38, 39 together. Both curtains then move together with the previously-established slot between them,