GB534370A - Improvements in or relating to photographic shutters - Google Patents

Abstract

534,370. Photographic shutters. KODAK, Ltd. Feb. 9, 1940, No. 2509. Convention date, Feb. 11, 1939. [Class 98 (i)] A shutter of the type comprising a pivoted aperture blade 15 to which a cover blind 10 movable by the shutter trigger 8 is latched so as to cover the aperture during movement of the blade in one direction to tension the spring, the latch being released at the end of the movement to permit the blade to move alone in the reverse direction to make the exposure, is provided with a retarding device comprising a gear segment 21 and weighted pinion 22 engaging it, one being carried by the shutter blade and the other by the casing. This causes the shutter to operate at a slower speed, and avoids change of speed due to gravity effects when the camera is held in different positions. In the form illustrated, Fig. 1, showing the parts before an exposure, and Fig. 3 after exposure but before release of the trigger 8, the cover blind 10 is secured to the shaft 9 of the trigger, and is provided with a latch element 11 which is engaged by the end of a spring arm 12, Fig. 7, extending from one edge of the shutter blade. On depression of the trigger, the blind 10 carries the blade with it until the end of the arm 12 rides up on a stud 20, the blade being thus unlatched and returning under spring action to make the exposure. The retarding means comprise a rack 21 formed on the edge of the block and engaging a pinion 22 to which a small flywheel 24 is attached. " Bulb " exposures are obtained by moving a lever 25 to cause the upturned end 28 of an arm 27 to arrest the blade in the open position. In a modification, the pinion is mounted on the blade, and engages a fixed rack segment. In another form, the pinion is carried on a pivoted arm so that it may be moved out of engagement, with the rack on the blade to give a shorter exposure. A modification providing a speeded shutter is shown in Fig. 12, a spiral spring 61 being secured at its inner end to the shaft 52 of the pinion 51 and at its outer end to a disc 56 which can be rotatably adjusted to vary the spring tension by an external knob 57.