GB767380A - Improvements in or relating to sheet or the like clamping and releasing mechanism - Google Patents

Abstract

767,380. Optical-projection apparatus. KODAK, Ltd. March 16, 1955 [March 19, 1954], No. 7654/55. Class 97(1) A hollow cylinder is mounted for rotary and axial movement and is provided with a device extending radially into it, for clamping one edge of a sheet to the cylinder surface, the clamping engagement being maintained during rotation in one direction but released when the rotation is reversed. In the form shown the drum 14 is carried on a shaft 30 journalled in end supports forming part of a framework slidable axially on rods 16, 16<SP>1</SP>. A plate 47 is slidable across the end face 38 of the drum; being retained thereon by a tongue 57 which passes through slots in the end face and carries an enlarged portion 61 behind the end face. The upper end 62 is similarly engaged behind the end face and continues longitudinally within the drum being coupled by inter-engaging tongues. not shown, to a member 45 running the length of the drum, projecting through a longitudinal slot and turned over to form a lip at 46. The plate 47 and hence the member 45 is urged radially inwards by a spring - 48 anchored to the plate and encircling the shaft 30. The lip 46 is thus urged into contact with the surface of the drum 14 and may be used to clamp one edge of a sheet to be wrapped round the drum. The member 47 carries an upwardly bent tongue 67<SP>1</SP> which, once per revolution of the drum in a clockwise direction, rides over a spring tongue 72 carried by the end plate in which the shaft 30 is journalled. The two tongues have a ratchet-like relation so that if the drum rotation is reversed engagement thereof lifts the members 47 and 45 to permit the edge of a sheet to be inserted under or removed from under the lip 46. The upward movement is limited by tongues 51 projecting from the member 45. Fig. 1 shows the device in an optical projector. A sheet, on the drum 14 rotatable by knobs 32, is illuminated, at a projection gate, not shown, and an image thereof projected episcopically on to the screen 12. Rotatable balls 78 maintain close contact of the sheet, with the drum 14 in the vicinity of the projection aperture. Alternatively a pressure pad may be used.