Abstract: In a scavengeless development apparatus, an electrode wire is disposed between a donor roll and a latent image to form a powder cloud of toner to develop the latent image. A magnet is disposed along the electrode wire, and low-frequency AC is passed through the electrode wire. The electromagnetic forces acting on the wire from the interaction of the AC with the magnetic field are adapted substantially to cancel mechanical vibration of the electrode wire.

Abstract: A scanner adapted to selectively discharge a charged photosensitive surface emits a plurality of light beams, with the plurality of light beams impinging on the charged photosensitive surface forming a composite light spot to discharge the charge thereon. The intensity of at least one of the plurality of light beams may be varied to adjust the position of the composite spot centroid on the charged photosensitive surface.

Abstract: A device for embossing electrophotographically printed sheets is operatively disposed downstream of a fusing station. The device includes a rotatable member having a relief defined on an edge thereof for pressing into the sheet. The rotatable member is rotated by the same mechanism that drives the fusing station.

Abstract: A raster output scanner system for multi-color printing provides a plurality of independently-controllable, substantially parallel writing beams. A rotating polygon causes the writing beams to scan simultaneously. The parallel beams are then reflected by a multifacet mirror and redirected to various photoreceptor surfaces. Each writing beam comprises a set of converging sub-beams, the relative intensity of which is adjustable to effect small positional adjustments of the writing beam on the photoreceptor surfaces.

Abstract: A multi-color imaging charge-coupled array comprises a plurality of photosensitive layers, each sensitive to a specific range of wavelengths as would be found in a full-color image. The various photosensitive layers are separated by boundary layers of high band-gap energy, so that charge packets formed within individual layers are insulated from charge packets formed in other layers within the same pixel. The combination of photosensitive layers and high band-gap boundary layers cause charge packets to be formed in potential wells within each pixel area of the charge-coupled array.

Abstract: A grating having holographic properties is employed in a pixel clock for a raster-output scanner. A pilot beam, off-axis from the writing beam creating a latent image on the photoreceptor, is focused on the grating. The grating is adapted to direct a portion of the pilot beam to a photodetector in a fixed point location. The holographic properties of the grating ensure that a wave associated with a reflected interference pattern is always directed at the photodetector throughout the scan path of the pilot beam.

Abstract: An apparatus in which a donor roll advances toner to an electrostatic latent image recorded on a photoconductive member. A plurality of electrical conductors are located on the donor roll. The electrical conductors are spaced from one another and adapted to be electrically biased in the development zone to detach toner from the donor roll so as to form a toner cloud in the development zone. In the development zone, toner is attracted from the toner cloud to the latent image. A predetermined significant resistance at the interface between a commutator wiping brush and the electrodes limits arcing as the roll rotates.

Abstract: A cartridge for supplying liquid ink to a thermal ink-jet printing apparatus includes a chamber having a ventilation port and an outlet port. A medium occupies at least a portion of the chamber, for retaining liquid ink therein at a predetermined back pressure. An open-ended conduit defines a passageway extending from the ventilation port to a portion of the chamber substantially devoid of liquid ink, to prevent leakage of liquid ink from the cartridge.

Abstract: A monitoring system for replaceable units, such as toner cartridges in an electrophotographic printer, includes on the unit an electronic count memory and an electronic flag memory. The count memory maintains a one-by-one count of prints made with the cartridge. The flag memory includes a series of bits which are alterable from a first state to a second state but not alterable from the second state to the first state. The bits in the flag memory are altered at predetermined intervals as prints are made with the cartridge. The flag memory is used as a check to override unauthorized manipulation of the count memory.

Abstract: Semiconductor chips, such as photosensor arrays in a full-width scanner, are mounted on a substrate to maintain reasonably consistent spacing among chips regardless of temperature conditions during use. After chips are tacked onto the substrate with uncured epoxy, the assembly is brought to a low temperature prior to the heating of the curing step. The technique permits design of the assembly to compensate for differences between the thermal coefficient of expansion of the chips and that of the substrate, while also minimizing mechanical stresses on the chips caused by heating in the course of use.

Abstract: A system, including a specially-designed optical element, facilitates extremely precise and accurate registration of a light beam on a photoreceptor. The optical element includes a redirecting cylinder lens, having a longitudinal axis oriented obliquely relative to the scan path of the light beam to redirect the light beam. The redirected light beam interacts with an aperture in the photoreceptor to provide an accurate measuring device for the exact position of the aperture with each scan.

Abstract: An ionographic printer directs a stream of ions from a source to a charge receptor to create an electrostatic latent image thereon. The ion stream passes through a relatively large aperture having associated therewith a focusing pinch electrode for narrowing the ion stream to a preselected width, and displacing electrodes for positioning the narrowed ion stream within the aperture. Varying the biases of the displacing electrodes causes the ion stream to scan across the aperture to deposit multiple spots of charged areas at desired locations on the receptor.

Abstract: In a development system for conveying toner to a latent image on a surface in an electrophotographic printing apparatus, including a donor structure spaced from the charge retentive surface for conveying toner to a development zone adjacent the surface and an electrode structure disposed between the donor structure and the surface, contaminants are removed from the development zone by a flow of air away from the development zone.

Abstract: A donor roll for the conveyance of toner in a development system for an electrophotographic printer includes an outer surface of phenolic resin. The resin is doped to a suitable conductivity to facilitate a discharge time constant thereon of less than 300 microseconds. The donor roll is used in conjunction with an electrode structure as used in scavengeless development.

Abstract: In an electrophotographic printing apparatus having a fuser roll and a second roll forming a nip therebetween for the passage of a copy sheet therethrough, each copy sheet is inserted through the nip so that at least one edge of the copy sheet is skewed relative to the direction of motion of the fuser roll.

Abstract: An agitator for agitating particles such as toner particles in an electrophotographic printer includes a stirring member having an elongated longitudinal member. Vanes are attached to the longitudinal member and form a gap therebetween. When the longitudinal member is caused to move within a cavity, the vanes act to clear toner particles from an area within the cavity associated with a sensor.

Abstract: Areas of a predetermined gray-scale in a desired image are printed on a sheet by a linear array of ink-jet ejectors. The individual ejectors are operated according to a probability function which controls the frequency of a random activation of the ejectors as the sheet moves past the ejectors. The frequency of activation is a function of the desired gray-scale of the area being printed. The resulting spots on the sheet are distributed in uniform lines in one dimension and randomly in another dimension.

Abstract: A system controls an ink jet printing apparatus for propelling ink jet droplets on demand from a printhead having a plurality of drop ejectors. In the printhead, each ejector includes a heating element actuable in response to electrical input signals, each input signal having an amplitude and a time duration, selectably applied to the heating element to produce a temporary vapor bubble and cause a quantity of ink to be emitted for the creation of a mark on a copy sheet. The temperature of ink in the printhead is sensed, and a combination of power level and time duration of the electrical input signal for the heating element to result in a desired size of the mark of the copy sheet is selected, by entering the sensed temperature of the ink into a predetermined function relating the energy of the electrical input signal to the corresponding resulting size of the mark on the copy sheet.

Abstract: A device prevents the migration of particles from the edge of a moving surface, such as a photoreceptor in an electrophotographic printing apparatus. A brush in contact with an edge of the surface includes fibers of a first type, and fibers of a second type. The fibers of the second type are less resilient than those of the first type and substantially incapable of abrading the surface. The brush guides the particles toward a bead-removal device.

Abstract: In the development system of an electrophotographic apparatus, a selected ratio of electrostatic charge per unit mass for particles adhering to a member transporting to a surface having a latent image recorded thereon is maintained. Means are provided for controlling a ratio of particle mass to the member surface area, and such means are controlled as a function of the selected ratio of electrostatic charge to unit mass to regulate the ratio of particle mass to the member surface area so as to substantially maintain particle electrostatic charge to unit mass ratio at the selected ratio of electrostatic charge to unit mass.