Patent GB-945805-A (GB)
Title: Pivoted blade shutter for photographic camera
IPC: G03B9/22
Filed: 1960-06-01
Abstract: 945,805. Photographic shutters. AGFA A.G. June 1,1960 [June 24, 1959], No. 19466/60. Heading G2A. A pivoted blade shutter for a photographic camera of the type having two blade rings which run down in the same direction to open and close the blades, one ring, which may be called the blade opening ring, moving while the other is stationary to open the blades, and the other, which may be called the blade closing ring, subsequently moving while the blade opening ring is stationary to close the blades and the blade closing ring being liberated for closing movement through the medium of the blade opening ring, includes a shutter speed regulating mechanism arranged either to retard the blade opening ring during the last part of its running down movement before release of the blade closing ring or to retard the blade closing ring during its initial running down movement after the blade opening ring has reached its final run down position. As shown (Fig. 1), an ever-ready shutter comprises blades 7 (only one of which is shown) pivotally connected to two spring loaded blade rings 3, 4, a spring urged hand release 25 pivoted about a pin 26 and having a stop pin 31 thereon against which a spring loaded pivoted member 30 is urged, and a retard mechanism comprising a flywheel 24, a gear wheel 22, and a spring urged toothed segment 13 which is pivoted at 14 and has two pins 17, 18, thereon for co-operation respectively with an impact surface 19 and a stepped cam 20 of a timing disc. On rotation of release 25 in the direction of arrow 33 member 30 comes against abutment 10 of the mutually engaging abutments 10,11 and the two rings 3,4 are thereby rotated together to their tensioned positions. In the tensioned position detent pin 17 of the spring urged segment 13 engages behind abutment 34 of the ring 4 to an extent determined by the engagement of pin 18 with the cam 20. After further rotation of release 25, member 30 slips off abutment 10 and ring 3 runs down under loading of spring 8 for opening of the shutter blades. Near the end of this running down, abutment 12 on ring 3 comes against a lug 16 on segment 13 and after a short delay - depending in length on the set position of segment 13 - pivots the segment 13 so that detent pin 17 releases the abutment 34. Ring 4 then runs down under loading of its spring 9 for closing of the shutter blades. In an alternative embodiment (Fig. 2), the detent 17 is replaced by a spring urged pawl 36 which is engageable in a recess 53 in the ring 4 when this ring is in its tensioned position. Further, the speed regulating arrangement is different. In operation, after the rings 3 and 4 have been tensioned by the release 25, and the ring 4 has been latched, the ring 3 is released by the member 30 and runs down freely to its rest position. At the end of this movement a pin 42 on the abutment 12 pivots the pawl 36 out of the recess 53 and thereby releases the shutter closing ring 4, movement of which is initially retarted by engagement of a lug 52 on the ring 4 with an abutment surface 48 of a modified retard mechanism 37, 46 and 50. As before, the length of delay is set by a timing cam 51. A modified hand release (Fig. 4, not shown) includes a single coiled spring for loading both the members 25 and 30. Fig. 3 (not shown) relates to a minor modification of the second embodiment in which separate cocking and release levers 54, 55 are provided.