Abstract: A magnetic roller comprising a diamagnetic cylinder rotatable about magnetic poles which extend axially inside the cylinder and are each formed by similar poles of magnets lying axially beside each other is made to generate a substantially homogeneous magnetic field over its full working width, thus enabling the magnets to be made of strongly ferromagnetic, anisotropic material, by the provision, over and along one or more of the magnetic poles between the magnetic pole and the diamagnetic cylinder, of a material having high magnetic permeability, such as a strip of soft iron of between 0.1 and 1 mm. in thickness fixed to and not wider than the surface of the magnetic pole.

Abstract: A profiled roller for pressing sheet material evenly against a roller that applies a film of liquid to the material, without collecting or forming a meniscus of the liquid in the absence of material to be moistened, comprises on a core a sleeve composed of many contiguous identical rings each provided with a peripheral series of protuberances that recur n times circumferentially thereof with each ring turned circumferentially relative to a contiguous ring at an angle thereto of less than 360.degree./n. The tops of the protuberances, each having a surface area of less than 0.5 mm.sup.2, define a cylindrical roller outline and are spaced apart by a distance of 1.5 to 4 mm, providing between them open spaces that will not retain the liquid by capillary action. The opposite sides of each ring are formed with complementary profiles disposed circumferentially apart at the said angle so that the rings may be readily assembled in the required angular disposition on the core.

Abstract: A copying apparatus provided with a system for transferring electrostatic or powder images from a moving image supplying surface to a moving intermediate surface for temporary retention on the latter, wherein the respective supports of the surfaces are pressed together during image transfer and are kept apart at other times, is made with an arrangement which assures synchronized movement of the two surfaces for image transfer by driving the supports at slightly different speeds yet causing one of them to be driven by friction with the other, precisely at its speed, while and at the location where the surfaces are pressed together for image transfer.

Abstract: A magnetic roller comprising a diamagnetic cylinder rotatable about magnets extending axially inside the cylinder is made to inhibit escape of magnetically attractable powder particles from the surface of the cylinder by providing the magnets, or a cylindrical magnet composed of several of them, with means which form in the magnetic field near each end of the cylinder a spirally extending bandlike field range which deviates in field strength from that existing in other regions of the cylinder surface. The bandlike ranges preferably have a reduced field strength and are formed by grooves made in the surface of the magnets and/or by applied strips of material having a greater magnetic permeability than air. They preferably extend from the extremities of the magnets spirally inward in the direction of the rotation of the cylinder, so that powder particles will be displaced inwardly from them as the cylinder rotates.

Abstract: A light reflecting casing especially suitable for use in photocopiers is provided by means of a resilient foil, e.g. of stainless steel or of a metallized flexible plastic material, which is held elastically curved with a reflecting side thereof directed toward the light and is shaped exactly to the form of a developable ruled surface by a plurality of support members engaging its other side.

Abstract: Electrophotographic copies having images of high optical density formed on photoconductive layers having little weight and suitably transparent for use as photocopying originals are produced by charging electrostatically and exposing imagewise a photoconductive layer of less than 10 g/m.sup.2 in dry weight and less than 6 microns in thickness which contains zinc oxide and a binder in a weight proportion of between 9 and 14 and is chargeable at most to a surface potential of between 100 and 250 V, this layer being carried on a conductive flexible support having a specific resistance of less than 10.sup.13 ohm. cm, and thereafter developing the resulting charge pattern by contacting it during at most 3 seconds with a "one-component" powder which contains pigment dispersed in resin and has a specific resistance below 10.sup.7 ohm. cm, while maintaining a conductive connection between the developing powder and said support.

Abstract: Copying apparatus of the type in which an original after being passed through a copying path with a copy sheet can be either delivered away or passed back through a return path into the copying path for making another copy is provided with a simple and reliable system for adjustably positioning a side edge of the original, even if it is fragile, relative to a side edge of the copy sheet so that the position of the images on multiple copies will not vary from copy to copy.

Abstract: Fading of the light-sensitivity of a dye-sensitized photoconductive layer used repeatedly for image formation in indirect electrophotographic copying is avoided by employing a photoconductive layer sensitized by a nitro-substituted dye such as a nitro-fluorescein or a nitro-phenolsulfonephthalein.

Abstract: In electrophotographic copying processes use is made of a reproduction element comprising on a conductive support a photoconductive layer containing dispersed in a binder a bisazo naphthol compound having a certain structure of substituents whereby the reproduction element exhibits relatively high light-sensitivity and is repeatedly exposable and developable imagewise so as to be useful for indirect electrophotographic copying. Special binder compositions enhance the light-sensitivity of the element and special layer constructions are provided to suit it for certain uses.

Abstract: Diazotype copies are produced from one-component diazotype material in a practically dry state without adversely affecting their feel or the speed of development. The diazotype material comprises a support and a light-sensitive surface layer having an average maximum thickness of not more than 8 micrometers and comprising 0.2-2 milligram molecules of one or more diazo compounds, which, in vitro, couple more actively than 4-diazo-2-chloro-N.N.-diethylaniline. After imagewise exposure the copy is developed by applying to the light-sensitive surface of the diazotype material a quantity amounting to 1.5 to 4.5 cm.sup.3 /m.sup.2 of an aqueous, buffered solution, which is at a pH of between 5.5 and 7 and which comprises per liter 0.1-0.6 g.mol of azocoupling component, consisting for at least 50% by weight of phloroglucinol and 1-3 g. equivalents of buffer salt. The diazo layer advantageously is formed by spreading 2-8 cm.sup.3 of sensitizing solution of adapted concentration onto the support.

Abstract: A cover device for pressing originals having different thicknesses with equal force against a glass exposure plate of photocopying apparatus comprises a bordering frame swingable between closed and open positions and, inside the frame, a platelike covering member which rests upon supporting elements of the frame when the frame is in open position, presses down upon an original on the exposure plate yet is displaced according to the thickness of the original as the frame is moved to closed position, and is guided from displaced positions to rest again upon said supporting elements as the frame is moved from closed to open position.

Abstract: Device for the assorted collection of sheets, comprising a transport track and bins situated along this track. The bins are provided with guide organs and each bin can be moved so that its guide organ protrudes into the track so as to guide a sheet into a bin. In the transport track the sheets are transported by means of belts running around a vacuum holddown device so as to hold the sheets onto the belts. The device may be arranged to receive copy sheets exiting from a copying apparatus and may be operated selectively in a first mode in which all similar copy sheets are delivered to a particular bin, or in a second mode in which sheets are collated into a predetermined number of bins.

Abstract: The electrophotographic properties of photoconductive elements sensitized by a cadmium sulfide-binder layer are improved by incorporating hydrophobic colloidal silica in the photoconductive layer.

Abstract: In a magazine for receiving, storing and delivering a long zigzag foldable belt having successive sections thereof stacked one upon another in upwardly bowed postures between zigzag folds bearing against oppositely disposed, downwardly convergent guide walls, proper placement of successive incoming belt sections on the stack within the magazine is effected, without need for precise synchronization of the feeding of the belt with the movement of fold positioning mechanism, by engagement of the entering belt folds with portions of continuously moving carriers, such as toothed belts or rollers protruding into and driven substantially vertically downwardly along upper regions of the magazine at the opposite sides thereof, which carrier portions displace the successive entering folds downwardly and lay them gently into their proper stacked position.

Abstract: A reserve supply of diazotype developing liquid from which liquid is supplied to semi-dry diazotype developing apparatus is maintained at both a substantially constant level and the required concentration of azo coupling component by introducing solvent for the liquid to restore the liquid level upon a decrease of the supply volume, sensing the specific gravity of the supply liquid by a hydrometer, and counteracting the decrease of concentration resulting from solvent addition by introducing a liquid concentrate containing the azo coupling component and electrolyte in response to a lowering of the hydrometer.

Abstract: Reproduction camera provided with means for displacing the lens and the original table, which include signal devices that emit electrical signals respectively representing the positions occupied by the lens and by the original table. Each signal device consists of a cam-roll type decade counting unit with drive shaft, of which each roll consists of a cam wheel with ten cams, and each cam wheel cooperates with a rotating ten-step switch with digital output.

Abstract: A stable panchromatically sensitized zinc oxide having a low moisture sensitivity with dark discharge properties rendering it suitable as the photoconductive material of elements for indirect as well as direct electrophotography is produced by reacting finely divided zinc oxide with gaseous ammonia and carbon dioxide, while keeping the zinc oxide particles in motion, until a critical stage is reached corresponding usually to a weight increase of 4 to 7.5%, at which point the reacting is terminated and the product is heated to constant weight at a temperature between 190.degree. and 350.degree. C. Photoconductive elements made with the panchromatically sensitive zinc oxide not only are reusable indefinitely under varying atmospheric humidity conditions without loss of their sensitivity, but also exhibit a memory effect much lower than that of known photoconductive zinc oxides.

Abstract: Reproduction apparatus with at least two objectives in a movable holder and an adjustable diaphragm. The holder and the diaphragm are provided with signal initiators which activate detectors in dependance on the position of the holder respectively the adjustment of the diaphragm.

Abstract: A device which is useful in development of diazotype paper said device comprising a liquid application roller, a dosing roller cooperating with it and one or more pressing organs to bring the diazotype material into contact with the application roller. In order to reduce liquid transport via the extremities of the rollers toward the pressing organs, the dosing roller is provided with limiting elements which are installed at the exhaust side of the dosing roller near the nip between this roller and the application roller and each limiting element consists of at least five plates, installed perpendicularly on the shaft of the dosing roller of which plates one side is closely adjacent to the cylinder surface of the dosing roller. The limiting elements transport superfluous liquid from said nip between the rollers toward the liquid reservoir and thus they inhibit the liquid transport toward the pressing organs which would wet the rear side of the diazotype material.

Abstract: Vinylpyrene (substituted or not) is prepared in a single reaction stage by reacting the corresponding acetylpyrene with a metal alkoxide, e.g. aluminum isopropoxide, in an inert organic solvent, e.g. a xylene, at a temperature above 110.degree. C. which, for some reaction conditions, optimally is between 130.degree. and 150.degree. C. The presence of hydroquinone in the mixture reduces the time and increases the yield of the reaction.