Abstract: A photoconductive belt for use in an electrophotographic copying machine has extremities thereof joined together in a manner keeping one side of the belt even for smooth movement through electrophotographic processing stations yet avoiding loosening of the joint by backward and forward bendings of the belt in its path in the machine. The joined extremities have end edges formations which mainly interfit yet each comprises lips that extend over the surface of the other extremity, all the lips being at the same side of the belt and being covered by an adhesive strip that joins the extremities together.

Abstract: Toner powders having excellent flow and non-agglomerating properties, and being readily removable from the imaging medium in use for indirect electrophotographic copying, are provided in the form of substantially spherical resin particles, containing additives or not as desired, which particles have been formed from irregularly shaped resin particles heated in a liquid dispersion containing hydrophobic silica particles smaller than 100 nanometers in diameter. The toner particles may be thus formed so as to carry on their surface or dispersed therein electrically conductive particles, such as carbon black, rendering them attractable by electrical inductance.

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: 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: 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: A self-sticking adhesive tape is provided which is particularly effective for joining free ends of a photoconductive belt at a side of the belt presenting a photoconductive layer of ZnO dispersed in a binding agent. The tape comprises a polyester support film provided on one side with a flexible electrically conductive layer to prevent retention of electrostatic charges and provided on the other side with an adhesive layer, made sticky preferably by an acrylate resin, having (a) an adhesive force of at least 200 Newton per meter and (b) a shear tolerance of not more than 1 mm, as determined by tests of the tape after its adhesive side has been adhered to such photoconductive layer. The conductive layer preferably consists essentially of a dispersion of carbon particles in a polymeric binder such as 60:40 copolymer of ethylene-terephthalate and ethylene-isophthalate, and the adhesive layer of a dried coating of an anionic dispersion in water of a finely divided acrylic ester containing carboxyl groups.

Abstract: Transfer of a powder image from a material carrying the image, such as a photoconductive material utilized for indirect electrophotographic copying, is effected magnetically by employing permanently magnetizable developing powder for forming the image, magnetizing the powder image, and bringing the powder image into contact with a first receiving support made of soft magnetic material so that this support is magnetizable and possesses a substantially uniform magnetic permeability over its whole surface but becomes magnetized so weakly that the powder image after being transferred to the first receiving support can be transferred readily from it, directly or indirectly, to a final receiving support which may be plain copy paper. The magnetizable material of the first receiving support has a coercive force of less than about 90 Oersteds and a relative magnetic permeability of at least 2.

Abstract: For control of an indirect electrophotographic copier employing an endless photoconductive belt having thereon at least one marking which excites a sensor each time the marking passes a fixed point in the belt path, the movement of the belt is measured electronically by a pulse generator coupled to a belt transport roller and a counter. Any difference between an electronically registered length of the belt and its actual length at a moment of sensor excitation is registered in a memory. At the end of a copying run pulses from the generator are diverted to the memory which then causes the difference to be corrected by discontinuation of the driving of the belt at an earlier or later moment.

Abstract: An apparatus for positioning a sheet-like original on the feed table of a copying machine comprises a plurality of sensors, mounted on the table, that have different states of response corresponding to the presence or absence of an original at the sensor on the table. The sensors are mounted in pairs, the sensors in each pair being arranged symmetrically with respect to the center line of the feed table that extends parallel to the direction of feed of sheet-like originals. A lateral transport mechanism causes an original, lying ready to be copied, to be displaced in a lateral direction, transverse to the feed direction.

Abstract: Charge images on a moving substrate such as a photoconductive belt surface are developed by being passed over two magnetic developing rollers in succession, which include nonmagnetizable cylinders rotatable in opposite directions about stationary magnet systems and are spaced apart outside each other's zone of influence in the upper region of a trough-shaped reservoir. The reservoir has oppositely sloped side walls converging to a bottom for holding a supply of developing powder, from which powder is supplied into a zone between the developing rollers for attraction to their surfaces by at least one magnetic transfer roller located between them and the bottom.

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.

Abstract: A photoconductive element giving prolonged service without appreciable deterioration of its properties as the imaging medium in an indirect electrophotograpic copier is obtained by the provision, on an electrically conductive support that preferably is electrically conductive paper coated with a thin layer of hydroxyethyl cellulose, of a photoconductive layer composed essentially of continuous tone zinc oxide and at least one other photoconductive zinc oxide dispersed in a binder consisting predominantly of an organic polymer having an acid number between 10 and 30, such as an acrylic resin or such resin with 1 to 15% of styrene-modified alkyd resin, at a weight ratio of between 5 and 3 parts of zinc oxide per part of binder. The content of continuous tone zinc oxide preferably is limited to a minor proportion amounting to between 6 and 30% of the total zinc oxide content.

Abstract: Transfer of a powder image from a material carrying the image, such as a photoconductive material utilized for indirect electrophotographic copying, is effected magnetically by employing magnetically attractable developing powder for forming the image and bringing the powder image while under the influence of a magnetic field into contact with a first receiving support that comprises a myriad of zones of a first material which are separated from each other by a second material, one of these materials being magnetizable and the other being not magnetizable. The materials preferably are metals giving the first receiving support a durable smooth surface. The zones of the first material have a diameter and inter-distance of, at most, about 5 times and preferably about 1 to 2 times the diameter of the largest powder particles to be transferred, so usually of about 50 to 100 microns.

Abstract: An apparatus for feeding sheetlike originals to be copied which has a defined path for conveying the original that includes a feed section with guide elements which together form a feed slot and a continuously driven roller for conveying an original introduced in the path further includes a sheet arresting element located downstream of the driven roller and movable between two positions, namely, a first position in which the arresting element blocks the path of conveyance, and a second position in which the arresting element lies outside of the path of conveyance.

Abstract: A device for covering the exposure plate of a copying apparatus includes a belt driven at intervals for transporting sheetlike originals from a ready position on the device to a copying position in which an original is covered and pressed on the plate by the belt, and the belt is so mounted and positioned that the same device serves for covering and pressing books and other objects of irregular dimensions placed on the plate for copying. A control circuit is provided which coordinates operations of the belt drive with the starting of operation of the copying apparatus and the presence of a sheetlike original in ready position.

Abstract: In a copying apparatus of the type employing a moving image-carrying belt from which an image is transferred to an intermediate support during the action of a device for pressing the belt against and advancing it with intermediate support, which is moved at a speed slightly lower than the speed at which the belt is driven, lengths of the belt leading to and from the belt pressing device are engaged by respective floating rollers which apply first and second forces tensioning the belt. The second tensioning force is kept greater than the first, thus acting when the pressing device is inactive to displace upward the belt lead to the pressing device, and an arrest device limits the upward displacement.

Abstract: An apparatus for conveying a sheetlike original to be copied through the exposure section of a copying machine and back again when multiple copies are desired includes an original return means having at least two sets original sheet gripping and conveying elements which have been mounted in a common supporting element which can be displaced cyclically to a number of positions, whereby, in each position of the supporting element and with the return means activated, one set occupies a position located in the path of movement of an original leaving the exposure section, and another set occupies a second position located in the path of movement joining the entry to the exposure section.

Abstract: The light emission of a gas-discharge lamp is controlled effectively by the action of a cooling organ making use of a Peltier element having its cold side thermally connected with a portion of the wall of the lamp and having its hot side thermally connected with means for discharging heat to the ambient, together with means for sensing the temperature at said wall portion and for regulating correspondingly an electrical current to the Peltier element.

Abstract: Powder particles blemishing the background of a powder image formed by attraction of toner particles to an electrostatic charge pattern on a photoconductive support surface are removed selectively without loss of the image by subjecting the image bearing surface to a limited electric field generated from a wall defining a suction mouth through which the powder particles attracted by this field from the support are sucked away. In an embodiment involving transfer of the powder image, the suction mouth serves also as a protective device for removing all powder particles from the support surface if a receiving material is not in position at the transfer station to receive the image, for which purpose a high voltage is applied at the suction mouth and/or the support surface is treated ahead of the suction mouth to diminish its charges attracting the image particles.