Patent GB-1175743-A (GB)
Title: Improvements in or relating to Photographic Cameras having a Pivoted-Flap Shutter
Inventor: BOEHM SIEGFRIED
IPC: G03B9/08
Filed: 1967-01-17
Abstract: 1,175,743. Flap shutters. PENTACON DRESDEN KAMERA-UND KINOWERKE VEB. Jan.17, 1967, No. 2469/67. Heading G2A. A shutter comprises two elements, each consisting of an arcuate part 20, 21, part 20 being supported between two side arms 15 and part 21 similarly between side arms 16. The shutter is disposed between the objective 2 and the gate 12 framing the film exposure aperture, and the exposure is made in the interval between swinging down first the shutter element 16, and then the element 17, from the cocked position of Fig.2 to the run-off position of Fig.6. The length of each arcuate part 20, 21 is such that separately they do not cover the whole height of the film gate. To the upper shutter element is attached one end of a flexible opaque curtain 22, and to the lower element a similar curtain 23. The other ends of the curtains are secured to tensioned rollers 24, 25 Fig. 2 or directly to the camera housing at 33, 34 Fig.6. The lower part of edge 20 is cranked, as at 32, to fit over the upper edge of part 21. Thus the cranked edges, together with the opaque curtains, ensure that in spite of the short length of the arcuate parts 20, 21 the film gate 12 has a light-tight covering in both the cocked position and the run-off position. Because of these short arcuate parts, the shutter can be accommodated in a reflex camera while still leaving enough room for the mirror 5 to swing into and out of position. The shutter is tensioned by the film-wind mechanism, which is geared to a pair of levers 36 and pivots these clockwise on a shaft 35, so that they engage the arms 15 and 16, driving them clockwise against their respective tensioning springs 18, 19 into the cocked position of Fig.2. The release is effected by a plunger which first unlatches levers 36, and then side arms 16, so that the lower shutter element pivots downwards to begin the exposure. After a period determined by a suitable timing device, the upper element is unlatched to pivot downwards and so terminate the exposure. Figs. 10 (not shown) and 12 include details of the mechanism controlling the movement of the reflex mirror 5 from the inclined "viewing" position of Fig.2 to the "exposure" position of Fig. 12. The lever 36, pivoted on shaft 35, has jointed to it at its farther end 74 a draw-rod 75. When the shutter is tensioned, a toothed end 76 of this draw-rod engages a pin 79 on a tap 78 which fits on one end of the mirror and pivots it down into the "viewing" position. It is latched in this position by a lever 81 which engages a pin 80 on the mirror, after which draw-rod 75 is uncoupled from the pin 79. When the exposure plunger 49 is pressed, it engages a lever 45 which unlatches lever 81 from the mirror, so allowing it to be pivoted upwards out of the light-path by a spring 86. Lever 45 then releases lever 36 to pivot anti-clockwise, hence releasing the shutter members as described above. Secured to shaft 35 of lever 36 is an arm 87 Fig.6 which, at the beginning of the running-off movement, engages a plunger 4 controlling the diaphragm, so that it is closed down from its full aperture setting during "viewing" to its predetermined exposure value.