GB412880A - Improvements in or relating to focal plane shutters for photographic cameras - Google Patents

Abstract

412,880. Photographic cameras. LEITZ GES., E., Optical Works, Wetzlar, Germany. Jan. 31, 1934, No. 3242. Convention date, Feb. 18, 1933. [Class 98 (i).] Shutters, roller-blind.-In a shutter where the slot is formed, after the shutter release, by a second blind following a first blind across the focal plane of the camera objective, the second blind is released for the longer time settings after a time interval determined by an escapement mechanism, which is only brought into action just before the first blind completes its movement, the driving force for the escapement being derived from the driving spring for the second blind. The driving bands for the first blind are wound on reels A<1>, A<2>, Fig. 6, rigid with spindle A, and the second blind is wound on a roller B freely rotatable on spindle A, driving springs tending to unwind the blinds from the reels and roller. A pin B <1> connects roller B to a member B<2> passing through the camera wall C. Pin B<1> passes through an arcuate slot A<3> in reel A<1> of sufficient length to allow the required relative movement of A and B. Lugs B<3>, B<4> on part B<2> coact respectively with a latch D, Fig. 1, and with an arm G<3> connected to the escapement K. A stop C<2> on the camera wall C<1> arrests a pin A<4> on reel A<2> when the first blind is fully unwound. A disc A<6> rigid with spindle A has holes to receive a pin E<1> on a setting knob E marked with the shorter time settings. To set, knob E is withdrawn and pin E placed in the appropriate hole so that the desired timing E<3> reads against a mark on casing C. Knob E carries a pin E<4> which depresses catch D to release the parts B<3>, B after spindle A and parts A<6>, E, E<4> have rotated through an angle determined by the setting of E. A spindle G is moved axially downwards, Fig. 5, just before the first blind is fully unwound, by a spring blade F, a projection F<1> of which is depressed by a cam A<7> on spindle A. The other end of spindle G passes through an arcuate slot C<3> in wall C and carries a pin G<1> pivoting in the free end of a crank H, itself pivoted at H<1>, the centre of arc C<3>. A spring H<2> tends to raise pin G<1>, Fig. 1, and to move rod G longitudinally against blade F. The rod is held down in slot C<3> by a cam J<1> on setting knob J for the longer time settings. Escapement K, Figs. 1 and 5, is connected by pin K<1> to an arm G<4> mounted on a part G<2> rigid with rod G. Arm G<3> on rod G coacts with lug B<4> on member B'. The escapement is thus driven by the driving spring of the second blind on roller B. For the position of Fig. 1, when the first blind is released, spindle A near the end of its rotation releases latch D and parts B3, B<2>, B ; lug B<4> meets arm G<3> and the escapement delays the rotation of the second blind until lug B<4> wipes free of arm G<3>. For the shorter exposures, rod G is raised to the top of slot C<3> so that arm G<3> is clear of lug B<4> and the escapement does not function.