GB720847A - Improvements relating to photographic pivoted blade lens shutters - Google Patents

Abstract

720,847. Photographic pivoted blade shutters. DECKEL, H., and DECKEL, F. W. March 25, 1953 [June 20, 1952], No. 8264/53. Class 98 (1). A pivoted blade shutter having a poweroperated master member which drives a rotatably mounted blade ring in opposite directions to open and close the shutter is characterized in that the point at which the master member acts on the ring to close the shutter is further from the centre of the ring than the point at which it acts to open the shutter. As shown, the master member 12 is set by anticlockwise movement of a ring 30 geared to a disc 34 having a depending arm 28 engaging an upstanding lug 24 on the master member and is held in the set position with the driving spring 16 tensioned by a pivoted pawl 42 engaging a lug 40 on it. During setting a lug 64 on the master member rides up and over the bevelled face of a resiliently mounted pin on the shutter blade ring 44. On tripping the pawl 42 manually or through a release means the master member rotates clockwise and the lug 64 engages the pin 50 to drive the ring 44 to open the shutter and while the shutter is open the lug 24 engages an arm of a gear sector 60 forming part of an exposure time-controlling retarding mechanism. Finally the lug 40 engages a pin 58 on an arm 56 extending outwardly from the ring 44 so moving the ring clockwise to close the shutter with a torque equal to the opening torque applied to the pin 50 although the driving power of the spring 16 has meanwhile diminished.