Patent GB-895903-A (GB)
Title: Automatic shutter speed control in photographic cameras
IPC: G03B7/083
Filed: 1958-10-08
Abstract: 895,903. Photographic shutters. GAUTHIER G.m.b.H., ALFRED. Oct. 8, 1958 [Oct. 18, 1957], No. 32143/58. Class 98(1). [Also in Group XL(b)] A photographic exposure is initiated at or soon after the beginning of the movement of a meter &c. energized from a photo-cell and is terminated when the movement reaches a limiting position. Four arrangements are described in some detail. First arrangement, Figs. 4..6. The stopcontrol of the camera is geared to an iris diaphragm 76 co-operating with the photo-cell, the relative openings being adjustable in accordance with other factors such as film speeds and filters. Diaphragm 9 may be replaced or supplemented by an adjustable grey wedge. Operation of a push-button 19 connects the photo-cell to the meter movement over a resistor and the resulting reading enables it to be ascertained whether the desired picture is possible. When the shutter is armed by means of lever 4a, spring 5 is tensioned, ring 3 for driving the shutter blades being latched at 21a. Operation of the shutter release button 32 energizes magnet 26 to release ring 3 and allow the shutter to open, ring 3 being latched at 24a in the open position. At the same time the meter is connected directly to the photocell and swings over releasing 26 when it moves off normal and, at the full scale position energizing 20 to allow the shutter to close. Modifications in which the same magnet initiates and terminates exposure Fig. 1 and Figs. 2, 3 (not shown) and Fig. 9 and Figs. 10, 11 (not shown). At the end of the arming movement of the shutter, member 4 in Fig. 1 is latched with the driving spring 5 under tension by inter-engagement of a projection from lever 45 with a projection on member 4. When the shutter release button is operated, magnet 20 is operated momentarily (the circuit including contacts opened when the meter pointer moves off normal as in the previously described arrangement). The shutter then opens but cannot close because the driving ring is latched by engagement of projection 3a with the part 45b of the lever 45. When the pointer reaches the limit of its travel it energizes the magnet again to allow the shutter to close. In the arrangement of Fig. 9 the ring 3 is latched after arming by the pivoted armature 47 of magnet 20 in its de-energized position. On the operation of the shutter release button, the magnet is energized and the shutter is latched open by engagement of a pivoted latch 51 with a projection 52. When the meter needle reaches full scale deflection the magnet is shunted out to disengage this latch and permit the closing of the shutter by the return of ring 3. Modification in which opening of shutter is initiated mechanically, Fig. 7. Member 4 is latched at 54c when the shutter is armed and separates contact springs 69, 70. On the operation of the shutter release lever 57a member 4 is released, allows the contacts to close and after some lost motion given by a pin and slot connection with the usual toggle, opens the shutter which is latched in the open position by engagement of detent lever 60a with projection 54c on member 4. Springs 69, 70 connect the photo-cell to the meter and when the pointer reaches its limit, magnet 20 is energized to rock lever 60a and allow the shutter to close. A switch 80 permits the disconnection of the magnet and the shutter then acts like an ordinary shutter in the "B" condition.