GB190602713A - Improvements in or relating to Photographic Shutters. - Google Patents

Abstract

2713. Dietz, G. Feb. 3. Shutters in which exposure is effected during the rotation of rotary blades from one closed position to a second closed position without reciprocation. The torsion in a helical spring is used for driving the shutter, the mechanism allowing the shutter to operate in either direction, and to be re-set without moving the blades. The escapement release comprises two elbow levers on the sime fulcrum, and relatively adjustable for time and bulb exposures. An air buffer is used in very fast exposures, and a pneumatic retarding-piston can be coupled to the driving-ring for slow instantaneous exposures. The blades d, Figs. 1 and 2, are thickened towards their pivots r<3>, and are actuated by pins r' on the driving-ring r, Fig. 6. The driving-spring b is attached between the bevelwheel a<1> gearing with the driving-ring r and the winding-wheel a<7>. The toothed section r<2> of the driving-ring is sufficient to rotate the blades from one closed position to the scond closed position. The ratchet-wheel a<7> is retained by the movable pawl a<8>, thus enabling the spring to be set in both directions. The driving-ring r is held by the pin e<3> on the release lever e engaging one of the recesses r<7> on the driving-ring. The release lever e is coupled with a smaller elbow lever e' carrying the time pin e8 by a pin on the handle e<10>. For bulb or time exposures, the pin is rotated to engage the righthand hole e<11> of the lever e, Fig. 1, s) that the pin e<8>, which for ordinary exposures is inoperative, then projects into the path of the stop r<8> on the driving-ring r when the release lever is operated: For time exposures, the pivoted lever t is swung over, the projection t<3> retaining the lever e until released by hand. For slow instantaneous exposures, a projecting pin p<2> on the driving-ring is coupled to the rod n<2> of the pneumatic piston n, which has a small air escape. In very fast exposures in one direction, a second projecting pin p cushions against the head m<4> of the piston m. The pin p can be used to turn the driving-ring backwards and so to re-set the shutter without the necessity of re-setting and rewinding the driving- spring b in the opposite direction. By rounding off the blades d as shown in Fig. 11, the light admitted through the aperture during an exposure is considerably increased.