Abstract: Apparatus for cleaning the photoconductive drum of an electrostatic copier in which a rotating foam roller and a self-cleaning squeegee blade are sequentially arranged adjacent the photoconductive surface at a location following the station at which the image has been transferred to copy material such as paper. The self-cleaning squeegee blade is formed by a driven endless belt which extends across the entire photoconductive surface and which is so disposed that an edge portion or portions contact the surface of the photoconductor. The endless belt is cleaned by means remote from the photoconductive surface. In various embodiments of the invention the endless belt contacts the photoconductive surface at an acute, a right, and an obtuse angle to a tangent to the photoconductive surface. Means is provided for supplying developer liquid to the developer applicator on start-up of the machine and to the cleaning apparatus upon initiation of a copying operation.

Abstract: In an electrostatic copier having an applicator electrode positioned closely adjacent but not touching the photoconductive surface on which there is a latent electrostatic image to be developed. The surface of the latent image and the surface of the applicator electrode move at the same speed, or the electrode may move at a greater speed. The electrode and the photoconductor are spaced from each other by a gap in the order of between three and six mils. The applicator roller is mounted with its lower segment immersed in a tank containing a developing liquid bearing charged toner particles. There is a mechanism for increasing the liquid to the gap, such as a drive for speeding the rotary electrode to more than the photoconductor speed. After the latent image has been developed, a metering roller, which is a roller whose surface moves in the direction opposite to the surface of the photoconductor, meters or dynamically removes a portion of the liquid from the developed image.

Abstract: The invention basically comprises systems and methods relating to the field of electrostatics and is concerned with multicolor electrostatic reproduction, printing or constituting on coated and uncoated print receiving media with multilayer apertured elements or screens carrying charge distributions in accordance with selected color separation patterns. Ions accelerated through the apertures of the multilayer element pass therethrough under modulation control dictated by the color separation pattern, thereby forming a modulated ion stream having a cross-sectional density pattern corresponding to the color separation pattern. Electrostatic latent images are formed with modulated ion streams and are developed in various ways.

Abstract: A deformable polyurethane roller, which may be either a squeegee roller or a blotting roller, is positioned to contact a liquid-developed electrostatic image on a photoconductor. The polyurethane roller has a resistivity of 10.sup.9 ohm-centimeters or less and a Shore A hardness of 45 or less. The roller is biased by a potential having a sign the same as the sign of the charged toner particles in a liquid developer which comprises an insulating liquid having charged toner particles disseminated therethrough. The bias on the polyurethane roller is such that it prevents streaking, smearing, tailing or distortion of the developed electrostatic image and removes so much of the liquid carrier of the liquid developer from the surface of the photoconductor that the just-moist developed image can be transferred to a carrier sheet. This enables a higher-boiling insulating liquid to be used as the carrier liquid in a liquid developer.

Abstract: Apparatus for removing excess developer liquid from the surface of a photoconductor carrying a layer of developer liquid of a predetermined thickness in which a mechanical barrier extending across the photoconductive surface is positioned at a distance from the photoconductor surface which is less than said predetermined thickness, in which the surface and the mechanical barrier move relative to each other so that the mechanical barrier has a trailing portion with reference to the direction of relative movement, and in which a low-pressure air barrier is provided in the region of adjacency of the surface and the mechanical barrier to inhibit wetting of the trailing portion of the latter by the developer liquid.

Abstract: The invention basically comprises systems and methods relating to the field of electrostatics and is concerned with multicolor electrostatic reproduction, printing or constituting on coated and uncoated print receiving media with multilayer apertured elements or screens carrying charge distributions in accordance with selected color separation patterns. Ions accelerated through the apertures of the multilayer element pass therethrough under modulation control dictated by the color separation pattern, thereby forming a modulated ion stream having a cross-sectional density pattern corresponding to the color separation pattern. Electrostatic latent images are formed with modulated ion streams and are developed in various ways.

Abstract: Apparatus for separating a sheet of paper to which a developed toner image has been transferred from a moving photoconductive surface by directing a high velocity flow of air against an edge of a leading portion of the sheet on the surface to separate said portion, and exerting pneumatic pressure on the separated sheet portion to separate the remainder of the paper from the photoconductive surface. The high velocity air stream is pulsed to coincide with the arrival of the paper edge at a predetermined point in the separating apparatus.

Abstract: An electrostatic latent image is impressed on a multilayer apertured screen to establish within the apertures electric fields that modulate the passage of charged particles through the screens so that the charged particles are distributed in correspondence with the image. After imaging the screen is operated to control the gray scale response thereof in order to optimize copy quality. The gray scale screen response is expanded by applying a bias voltage of at least two different values to the screen during the duplication interval. The response is limited by altering the latent image charge to provide a high density cutoff and by applying a bias voltage to establish a low density cutoff during the duplication interval. Copy quality is further improved by adjusting the integrated charged particle current to establish the desired degree of density in regions of the copy image corresponding to high density regions of the original image.

Abstract: A document feeder for moving documents across an upwardly facing imaging platen of a copying machine includes a stacking tray disposed above the platen and in substantially parallel relationship therewith. A first guide element guides documents moving off the imaging platen at one edge thereof along an upwardly extending curved path and discharges the documents at one end of the stacking tray along an upwardly directed trajectory. A second guide element intercepts documents discharged along the upwardly directed trajectory at a location above the top of the tray and guides the documents downwardly into the stacking tray, thus obviating interference between a document moving into the tray and a bent or curled document already in the tray.

Abstract: An automatic background brightness control for document copiers of the type using automatic feeders for advancing original documents along a transport path to an imaging platen at which the documents are copied. As the feeder advances a document to the imaging platen, one or more light sources disposed at spaced locations across the transport path direct scanning beams onto the indicia-bearing side of the document. Photodetectors sense the light reflected from the scanned portions of the document to provide signals indicating the reflectance of the scanned portions. A signal-processing circuit responsive to the reflectance signals generates a background brightness control signal representing the maximum reflectance sensed by any of the detectors. The background brightness control signal regulates the intensity of the exposure lamp of the copier when the document reaches the imaging platen.

Abstract: A semi-automatic document feeder for use with a photocopying machine in which each of a plurality of parallel spaced belts supported by first and secondary pulley assemblies has a lower traverse running across the machine imaging platen. Documents which are introduced to the feeder through an entrance port located near the top of one of said pulley assemblies, are guided around said pulley assembly onto a lower transport path defined by the plurality of belts and the imaging platen, and are stopped for copying by a gate located on the opposite edge of the machine platen and arranged to be moved into and out of the path of a document.

Abstract: The invention basically comprises systems and methods relating to the field of electrostatics and is concerned with multicolor electrostatic reproduction, printing or constituting on coated and uncoated print receiving media with multilayer apertured elements or screens carrying charge distributions in accordance with selected color separation patterns. Ions accelerated through the apertures of the multilayer element pass therethrough under modulation control dictated by the color separation pattern, thereby forming a modulated ion stream having a cross-sectional density pattern corresponding to the color separation pattern. Electrostatic latent images are formed with modulated ion streams and are developed in various ways.

Abstract: An electrophotographic liquid developing system for overcoming the effect of photoconductor background potential in which during the passage of the image area through the developer unit a constant current source supplies a small current to the development electrode to raise the electrode to a potential of the same polarity as and of a magnitude greater by predetermined amount than that of the average background potential of the image area. In a preferred embodiment the constant current source is provided by a small plate mounted in and insulated from the transfer corona housing and having such dimensions as to provide the required current. Preferably, the output of the constant current source is controlled in response to a measurement of the conductivity of the developer.

Abstract: An electrophotographic liquid developing system for overcoming the effect of photoconductor background potential in which during the passage of the image area through the developer unit a constant current source supplies a small current to the development electrode to raise the electrode to a potential of the same polarity as and of a magnitude greater by predetermined amount than that of the average background potential of the image area in a preferred embodiment the constant current source is provided by a small plate mounted in and insulated from the transfer corona housing and having such dimensions as to provide the required current. Preferably, the output of the constant current source is controlled in response to a measurement of the conductivity of the developer.

Abstract: An automatic control system for the bias on a development electrode in which a plurality of ground-insulated, narrow floating electrodes are spaced along a line adjacent the entrance of a liquid developer applicator unit. The floating electrodes relatively scan image areas of the surface of an organic photoconductor carried by a conductive support moving through the developer unit. Owing to conduction of a charge from the photoconductive surface through the developer liquid to the floating electrodes, they assume potentials each of which is a function of the average potential of the image area subtended by the floating electrode. The potential of each floating electrode is sensed by a high input impedance measuring circuit which selects the potential of the lowest value, amplifies the selected potential and applies the amplified voltage to the biasing electrode or electrodes of the developer system.