Abstract: A corona device suitable for use in electrophotographic apparatus to provide a uniform charge on photoconductive material comprises as the ion-generating means a multiplicity of electrode pins, all of the same diameter, which are provided at the same mutual spacing from one another in a body of insulating material from which all the pins project to the same extent, with the pins limited to a diameter between 10 and 100 microns, a mutual spacing of between 0.3 and 2.5 mm, a projecting length of between 0.7 and 3 mm, a length to diameter ratio of between 10 and 300 and a spacing distance to diameter ratio of between 4 and 250. The electrode pins are formed from lengths of a suitable conductive wire which are laid at the required mutual spacing and soldered to and between conductive strips to form an electrically conductive unit that is embedded in a cast body of the insulating material with free ends of the wire lengths projecting to the required extent.

Abstract: A reproduction apparatus comprises a rotatable drum having trained over its circumferential surface a length of finite belt that extends and is transportable back and forth between two supply reels inside the drum and is impressible with image information to be transferred to receiving material at a transfer station adjacent to the drum surface. During transport of the belt in either direction relative to the drum surface the drum is held at a peripheral velocity which depends upon the direction of the belt transport and, considering both magnitude and direction, is equal to a given processing velocity of the belt relative to the transfer station minus the velocity of transport of the belt over the drum surface. Thus, the transport of the belt relative to the transfer station is always in the same direction and of the same magnitude, whether the belt is being transported from one reel to the other or back from the other to the one reel.

Abstract: A drying apparatus for drying material treated with liquid by heating and circulating a drying gas and for recovering vaporized liquid absorbed by a drying gas comprises at least one chamber unit which is essentially completely closed to the external atmosphere, a heating system in the chamber, a condensing system located in the chamber lowermost portion, means for guiding the material, in the form of a web, through the chamber through slot-like inlet and outlet openings such that the web is maintained free of contact at its wet surface, and a drying gas circulation system which divides the drying gas into several streams.

Abstract: In a process for the formation of an electrostatic image on a photoconductive element comprising a photoconductive zinc oxide-binder layer and an insulating top layer, the top layer is first positively charged and then is negatively charged until the element is saturated with negative charge, after which the top layer is imagewise exposed to light.

Abstract: A system for feeding originals one by one from a stack of them to the illumination station of a copying machine and finally back to the top of the stack, so as to enable automatic production of sets of correctly sequenced copies of double-sided and/or single-sided originals, comprises a holder for stacking originals, means for removing the bottom original from the holder, a first transport path for transporting the original from the holder to the illumination station via its inlet side with the side of the original that faced downward in the holder in position for copying, means for transporting the original from the exit side of the illumination station into a reversing path and from the reversing path again via the inlet side to the illumination station, and means including at least part of the reversing path and a final transport path for returning the original from the exit side of the illumination station to the holder and placing it in its original orientation on top of the stack.

Abstract: An improved continuous centrifugal machine includes a rigid base structure, a bearing housing, a normally vertical basket shaft journalled for rotation on bearings in the bearing housing, an upwardly open frusto-conical centrifugal basket secured to the upper end of the basket shaft for rotation therewith, a stationary curb wall mounted on the base structure and surrounding the basket, buffering assemblies for resiliently mounting the bearing housing on the base structure to permit gyration of the basket, and a motor mounted to one side of the curb wall and connected by an improved system to the lower end of the shaft for rotating the basket. In accordance with improvements in the machine an annular support ring is mounted on the base structure within the curb wall and has an upwardly facing surface.

Abstract: A holder for electrographic developing powder comprises an oblong outlet opening for the powder and has the opening covered by a membrane and by a slide valve which is movable along channels bordering the opening and is provided near one of its ends with a cutting device that cuts the membrane as the slide valve is moved from a first position closing off the opening to a second position not covering the opening. The holder comprises a flexible end portion that can be contracted by being pinched in a direction substantially parallel to the plane of the slide valve, and from which projections extend laterally for engagement with notches in guides that support the holder over a powder reservoir. The cutting device is moved toward the flexible end portion as the slide valve is moved from the first to the second position.

Abstract: In an apparatus for copying sheetlike originals, wherein a transport system feeds originals from a positioning surface onto an exposure plate and from the latter after exposure to a receiving tray, the positioning surface presents at least two distinct areas upon each of which an original can be laid ready to be fed in for copying and each area is bordered by a lateral arrest so that plural originals laid ready in the areas and against the arrests will be fed together to exact positions on the exposure plate for copying on one sheet of receiving material in one copying run of the apparatus. A system of open-front trays for piles of originals, each aligned with one of the positioning surface areas, facilitates the laying of originals in ready position. A control system responds to sensed presence of a complete set of originals in ready position to start a run.

Abstract: An optical apparatus for setting any one of a plurality of lenses in a certain operating position and for setting the opening of at least one of the lenses comprises a lens turret rotatable around an axis and having the lenses mounted thereon at locations spaced apart about the same axis, a gear on at least one of the lenses and turnable relative to the turret for adjusting the lens opening, and a drive system including a shaft coaxial with and rotatable in either direction about the axis and carrying a drive gear engaging each adjusting gear for turning the lens turret and each adjusting gear. At least one of the adjusting gears has a limited range of rotation relative to the lens turret in at least one direction so that the turret is rotatable by the drive gear through an adjusting gear when the latter is at a limit of its range of relative rotation. Preferably each lens is provided with an adjusting gear and only one drive gear is employed, which at any moment drivably engages all the adjusting gears.

Abstract: A mechanism for setting an optical system accurately to any of various reproduction ratios comprises at least one carrier which has an optical element or elements mounted thereon and is movable along an optical axis to any selected one of several set positions corresponding to desired reproduction ratios by a buffered four-position pneumatic cylinder having oppositely extending piston rods connected respectively with the carrier and a frame part. The four-position cylinder can be adjusted to set the carrier exactly at the position required for a desired reproduction ratio without affecting the settings that provide other ratios. The carrier may be an objective carrier carrying an objective holder that can be moved relative to it in a plane perpendicular to the optical axis and is so moved as the carrier is moved between its set positions; and a movable part of the objective is adjusted at the same time.

Abstract: The explosive 2,4,6-trinitrotoluene (TNT) is desensitized by dissolving it in oleum of from 10 to 40% (by weight) in strength. The solutions formed preferably contain at least 400 g and at most 480 g of dissolved TNT per liter of oleum in oleum of 20-25% strength. They are especially useful for the preparation of phloroglucinol.

Abstract: For reversal development of an electrical potential pattern formed by imagewise exposure of a uniformly charged photoconductive layer, the charging of the layer is restricted to such a level below its breakdown voltage that the contact between the photoconductive layer and the toner powder used in the development step is insulating, and a magnetisable and inductively attractable toner powder is applied for the development. The toner powder is applied by means of a magnetic brush device comprising a conductive development roller which is provided with an electrical potential suited for reversal development. Preferably the photoconductive layer is charged to a level of at most 35-75% of its breakdown voltage, and a scorotron preferably is used for the charging. The photoconductive layer may comprise a photoconductive polymer and/or a bisazo pigment as photosensitive compound, or may be a layer of "pink" zinc oxide dispersed in a binder.

Abstract: A composition and process for developing diazotype material utilizes a developing liquid comprising a buffered, aqueous solution of an azo-coupling component having a pH between 5.5 and 8 and, as an additive compound, sorbic acid, an alkali metal salt, ammonium salt, or magnesium salt of sorbic acid or mixtures of the same. The process produces a clear copy image more quickly than a process in which the developing liquid does not contain the additive compound and, when the azo-coupling component is a mixture of phloroglucinol and resorcinol, forms a neutrally black image. The additive compound is added in an amount of 10 to 80%, and preferably 30 to 60%, by weight, of the maximum amount soluble in the solution at room temperature.

Abstract: An electrophotographic element that comprises an electrically conductive support and a photoconductive layer containing a photosensitive azo-compound dispersed in a film-forming polymeric binder is prepared by synthesizing the photosensitive azo-compound in situ, by reaction between a diazonium compound and an azo-coupling component, in the film-forming polymeric layer on the support. The azo-compounds thus synthetized are distributed in the binder layer in an almost perfectly homogeneous form. Under an electron microscope screen scan they are not distinguishable as separate particles, even at a ten thousand fold magnification. By forming a very thin photoconductive layer in this way and coating it with a charge transporting top layer, especially useful electrophotographic elements are obtained. The invention relates also to electrophotographic elements prepared according to the process.

Abstract: Electrically conductive developer powder for developing electrostatic images by inductive attraction is provided, with avoidance of practical disadvantages of known "one-component" developer powders, by incorporating finely divided water-insoluble quaternary ammonium salt into thermoplastic resin particles forming the powder, with or without other finely divided additives such as coloring material and/or magnetically attractable material. The specific resistance of the resin particles is lowered to between 10.sup.7 and 10.sup.11 ohm. cm by from 8 to 35% by weight of the quaternary ammonium salt, and can be lowered further by additions of fine conductive material such as carbon black. The resin particles remain sufficiently fusible even when they also contain enough magnetically attractable material, e.g. about 50% by weight, to render them transportable by a magnetic powder-applicator.

Abstract: Apparatus for transporting sheetlike originals past an exposure plate (10) of a copying apparatus, of the kind in which a flight of at least one endless belt (25) is driven over the exposure plate, is provided with a device (80) for applying a solid abherent material (85) to that surface of the belt (25) which comes into contact with the exposure plate (10).

Abstract: Transverse areas lying between image areas of a moving photoconductive element can be discharged efficiently with sharp demarcations between the respective areas by an exposure device in which a flash lamp is disposed perpendicularly between two elongate side walls of a reflective housing having an open side and an elongate light-reflecting rear wall. A protective cover fixed near the lamp at the open side prevents direct radiation of the element from the lamp. Scatter of the reflected light is prevented by partitions fixed in parallel to the side walls in end regions of the housing space.

Abstract: Diazotype material having a thin light-sensitive layer that is developable excellently by a limited application (1.5 to 4.5 cm.sup.3 /m.sup.2) of a buffered aqueous solution of an azo component, and which adheres well to the support even in moist condition, can be obtained by providing on a paper support a light-sensitive layer containing a binder and filler with at least one diazo compound, when the binder comprises a condensation product of an amino compound with formaldehyde, e.g. cross-linked hexamethoxymethyl-melamine, and a hydrophilic polymer crosslinkable with said product, e.g. highly hydrolyzed polyvinyl alcohol, and the filler comprises starch particles, e.g. rice starch powder, in a weight proportion to said polymer of at least 5 to 1, and even as high as 30-70 to 1. A water-sealing layer on both sides of the support, or only on a side beneath the light-sensitive layer, renders the material curl resistant.

Abstract: In a system for developing electrostatic images on a moving photoconductive support by contact with a brush of two-component developer powder carried on a moving surface, in which the toner content of the powder is controlled in response to optical sensings of the reflectance of the brush at a location just beyond the developing zone, objectionable fluctuations of the toner concentration are avoided by shaping the developer brush to a constant layer thickness, for instance by reducing its thickness to about 0.5 to 0.6 mm, as the brush is being transported from the developing zone so that the sensings of the reflectance will occur at a constant distance from the brush. As an aid for adjusting or checking the operation of the toner control system, a reference surface having the same reflectance as a developer layer of the prescribed thickness and toner concentration is inserted in place of the brush at the location where reflectance is sensed.