GB736214A - Improvements in sliding plate shutters for a photographic camera - Google Patents

Abstract

736,214. Photographic sliding plate shutters. BERGERHOFF, H. Jan. 29, 1951 [April 26, 1950], No. 2179/51. Class 98 (1). A sliding plate camera shutter comprises two shutter plates movable longitudinally in planes parallel to that of the image-recording surface and coupled by means of a pivoted lever in frictional engagement with one of the plates whereby both plates are movable simultaneously to provide an exposure slit between their adjacent edges, means for varying the slit width by relative longitudinal sliding movements of the plates, means for moving the adjusted shutter plates perpendicularly across the optical axis of the camera, and tensioning and release means connected to at least one of the shutter plates. As shown, the two shutter plates 6, 7 are slidably mounted in guides 2, 3 on a back plate 1 and are coupled by a lever 11 pivoted at 12 on the plate 7 and bearing a pin 16 guided in an arcuate slot 18 in the plate 7 and engaging in a vertical slot 19 in the plate 6, the parts being maintained in their adjusted relative positions by friction. The shutter is set by moving clockwise a rotatable cover plate (not shown) which caps the shutter before its pin-and-slot connection with a rotatable non-capping tensioning disc engaging a pin 29 on the plate 7 causes movement of the plates 6, 7 to the left tensioning the driving spring (not shown) secured to the pin 29 and the shutter is held set by engagement of the pin by the hooked end 50 of a lever 35. On releasing the cover plate it is spring-returned to uncap the exposure aperture. When the shutter is set the lever 11 is adjacent an annular toothed sector 23 which is rotatably supported by pins slidable in arcuate slots 22 in a front plate 21, the slit width is adjusted by rotating a pinion 25 on the front plate. Separate vertically slidable release members 43, 44 are provided for instantaneous and prolonged exposures. On depressing the member 43 the lever 35 is rotated anticlockwise to release the pin 29 while on depressing the member 44 an additional lever 38 is simultaneously moved anticlockwise to bring its hooked end 56 into the path of the pin so that the shutter is held open by it. If the member 44 is depressed further than is necessary to effect a bulb exposure it is latched in the depressed position by a detent 57, giving a time exposure. To ensure that for prolonged exposures the shutter aperture is fully open, a disc having a circumferential slot in which engages a pin 62 on the member 44 is rotated by the aperture adjusting means and prevents depression of the member 44 until the disc presents a radial slot to the pin 62 when the shutter slit width is equal to the exposure aperture. In a modification for instantaneous and bulb exposures only a single release member is provided which can be rocked into alternative positions in one of which it actuates only the lever 35. Specification 430,648 is referred to.