GB870335A - Improvements in or relating to photographic cameras fitted with focal plane shutters - Google Patents

Abstract

870,335. Photographic cameras. KAMERAWERKE NIEDERSEDLITZ VEB. Sept. 25, 1957 [Sept. 28, 1956], No. 30032/57. Class 98(1) In a focal-plane shutter, in which the starting position of an index pin, which travels synchronously with the' leading shutter member, can be varied to vary the exposure time and the distance of travel to the point in its path at which the trailing shutter member is released, another pin, which also moves synchronously with the leading shutter member, drives a retard mechanism and prevents the first pin from reaching the trailing member release point until the desired exposure time has elapsed. As shown, two blinds 6, 7 are wound on coaxial rollers 10, 11 respectively, and the trailing blind roller 11 is retained in the set position by the engagement of latch 29 with pin 30 carried by member 31 rotatable with roller 11. The shutter is wound by means of a knob on spindle 18 fast with non-return ratchet 21 which carries pawl 23. Pawl 23 pushes gear wheel 17, which is freely rotatable on spindle 18, by means of nose 19 and roller 10 is driven through gears 14-16 to wind blind 6 on roller 10 and tension the counter spring roller (Figs. 4, 6, not shown). Nose 32 on gear 14 engages pin 33 on member 31 to wind blind 7 on roller 11 against its spring tension. The shutter speeds are set by engaging an index pin (Fig. 1, not shown) in holes 24 in gear wheel 14 which is fast with shaft 12 of roller 10. On actuating shutter release button 43, pawl 23 is removed from nose 19 and blind 6 runs down carrying the pin in a hole 24 into engagement with a lever 27 of latch 29 to release pin 30 and blind 7. However, if a pin 35 carried on wheel 14 reaches an arm on a toothed segment 36 before the pin in a hole 24 reaches lever 27, a gear retard 37-40 slows blind 6 (which is clear of the exposure aperture) before blind 7 is released. The holes 24 are accordingly so spaced that at an appropriate instant in the running of the retard, the lever 27 is actuated and the trailing blind 7 released. On re-winding the shutter, the gear retard is returned under its own spring 41. In another form (Figs. 4-6, not shown) two separate non- coaxial blind rollers 10, 11 are provided. Sliding plate and pivoted disc focal plane shutters operating on the same principle are referred to.