Abstract: In a printing apparatus for creating images on a sheet in response to digital data, the incoming data is polled for image data corresponding to a preselected density condition, such as a particular half-tone, on an area of the final image. The area having the density condition can be used as a test patch to monitor overall print quality.

Abstract: A photosensitive apparatus comprises a single crystal structure, wherein different regions of the structure are of different compositions. A first photosensitive region comprises a material adapted to generate electron-hole pairs in an area thereof exposed to light within a predetermined first range of wavelength, and a second photosensitive region, comprises a material adapted to generate electron-hole pairs in an area thereof exposed to light within a predetermined second range of wavelength different from the first range of wavelength.

Abstract: A development unit for electrostatic printing is designed to eliminate used developer at a steady rate. A barrier mounted in the housing defines in the housing a first chamber adapted to store a supply of developer material therein, and a second chamber adapted to receive excess developer material from the first chamber of the housing. A transport is mounted in the second chamber, for advancing developer material from the barrier.

Abstract: An ink-jet printer comprises a printhead including a front face defining an array of nozzle openings for the emission of ink droplets therethrough. A shuttle, including a wiper closely associated therewith, is disposed on a track adapted for the traveling of the shuttle through a fixed path generally parallel to the array. As the shuttle moves along the array, a mechanism including a lead screw causes the motion of the wiper against a portion of the front face of the printhead in a direction perpendicular to the direction of the array.

Abstract: An electrostatic discharge protection device for a connector associated with an integrated circuit chip, particularly one associated with a thermal ink-jet printhead. A MOS field effect device extends along at least one edge of the connector on the chip. A bipolar transistor, parasitic to the field effect device, conducts current from the connector to ground in response to a voltage between the connector and ground in excess of a predetermined threshold. A zone of a predetermined electrical resistance is operatively disposed between the bipolar transistor and ground. The zone may substantially encircle the bonding pad of the connector to evenly distribute local incidences of high voltage. The invention enables integrated circuits to pass ESD requirements of office products, which is 15 kV by Human Body Model testing.

Abstract: A thermal ink-jet printhead comprises a substrate having a plurality of heating elements defined thereon. A thermistor, disposed on the substrate, includes a conductor loop which does not encompass the heating elements on the substrate. The configuration of the thermistor significantly reduces both electromagnetic and capacitance interference caused by the heating elements.

Abstract: A system for supplying liquid ink to a thermal ink-jet printing apparatus comprises a housing defining a single chamber having a ventilation port and an outlet port. A medium occupies at least a portion of the chamber, the medium being adapted to retain a quantity of liquid ink. A scavenger member is disposed across the outlet port, providing a capillary force greater than that of the medium.

Abstract: In a raster input scanner, an original image is converted into digital image data. A scanning bar having at least one array of photosites is moved relative to the original image, whereby the photosites are sequentially exposed to light within a range of intensities reflected from locations on the original image. Each of the image signals from the photosites is integrated as the scanning bar moves relative to the original image, some signals being integrated for a first duration to yield a long-integration image datum, and some signals being integrated for a second duration shorter than the first duration to yield a short-integration image datum. One of the long-integration image datum and the short-integration datum is selected for each location in the original image, depending on the intensity of light associated with the location in the original image.

Abstract: A write head magnetizes magnetic-ink characters for a MICR system. A magnetic assembly defines a first pole in a first location and an opposite pole in a second location. A first pole piece and a second pole piece, spaced by a gap therebetween, are provided, the first pole piece disposed adjacent the first location and adapted to conduct a magnetic field from the first pole to the gap. A selectably positionable member is disposed between the second location and the second pole piece, the positionable member being adapted to affect a magnetic field from the second location through the second pole piece to the gap, thereby facilitating selectable alteration of a magnetic field profile across the gap.

Abstract: A capping and maintenance station for an ink-jet printer provides immersion of a printhead into a supply of ink of the same type as emitted by the printhead, when the printhead is not in use. The immersion provides cleaning and priming, and prevents drying of ink within the printhead.

Abstract: A photosensor for measuring the reflectivity of a surface is calibrated for consistent gain and offset. The reflectivities of a plurality of regions of a test surface are measured. An average of the measured reflectivities is calculated, and a threshold value related to the average is derived therefrom. A revised average of the measured reflectivities is then calculated, the revised average being an average of measured reflectivities only of regions having reflectivities of a predetermined relationship to the threshold value. Subsequent signals from the photosensor are then revised according to a function related to the revised average.

Abstract: A system controls the concentration of toner in developer in an electrophotographic printer. Toner is applied on a test patch on a charge-retentive surface in a manner consistent with a desired toner density on a test patch, and the actual toner density on the test patch is measured. The charge applied to the charge-retentive surface is then adjusted in response to the measured actual toner density to obtain the desired toner density on a subsequent test patch. The change in charge applied to the charge-retentive surface is used to detect a shortage of toner in the developer.

Abstract: A system controls a transformer having a primary coil. A pulse is applied to an inverter associated with the primary coil, whereby a leading edge of the pulse creates in the primary coil a tank circuit current of an initial polarity in a tank circuit inherent to the transformer. The tank circuit is seen from an effective inductance in series with the primary coil, the effective inductance including a leakage inductance of the primary coil, and an effective capacitance in parallel with the primary coil, the effective capacitance including a parasitic capacitance of the transformer. A trailing edge of the pulse occurs when the tank circuit current is different from the initial polarity.

Abstract: A control method for optimizing print quality in an electrophotographic printer uses a fuzzy-logic technique with solid-area, halftone, and light toner density as control inputs, and scorotron voltage, ROS laser power, and cleaning voltage as outputs. The fuzzy-logic program involves two two-input error subset matrices, one for simultaneous readings of solid-area and halftone densities, and one for successive light toner density readings.

Abstract: An apparatus develops an electrostatic latent image on a charge-retentive surface. A donor roll is selectably rotatable in a process direction and in a reverse direction relative to the process direction. A toner mover loads toner particles onto a portion of the surface of the donor roll. A metering blade is disposed downstream of the toner mover in the process direction. A seal is disposed upstream of the toner mover in the process direction, and is adapted to remove at least approximately half of the undeveloped toner from the donor roll.

Abstract: A photosensitive apparatus comprises a single crystal structure, wherein different regions of the structure are of different compositions. A first photosensitive region comprises a material adapted to generate electron-hole pairs in an area thereof exposed to light within a predetermined first range of wavelength, and a second photosensitive region, comprises a material adapted to generate electron-hole pairs in an area thereof exposed to light within a predetermined second range of wavelength different from the first range of wavelength.This application incorporates by reference a previously-filed application, Ser. No. 07/973,811, entitled "Color Imaging Charge-Coupled Array with Photosensitive Layers in Potential Wells," filed Nov. 5, 1992, and having the same inventor and assignee as the present application.

Abstract: In a raster input scanner adapted to perform multiple scans of a document through a series of color filters, a mechanism exploits the reciprocating motion of the scanner relative to the document platen to effect the changing of filters between scans without the addition of a separate motor.

Abstract: A developer unit for an electrophotographic printer includes a housing defining a chamber for retaining developer material. An auger is rotatable within the chamber for the conveying of developer material within the chamber. The auger and a second rotatable member are adapted to receive rotational drive from a single source of rotational motion. A clutch is responsive to a torque above a predetermined level associated with the auger. A selectably openable outlet port is adapted to permit escape of developer material from the chamber. A linkage is operatively disposed between the clutch and the openable outlet port. A torque above a predetermined level associated with the auger causes the clutch to move the linkage, causing the mechanical linkage to open the outlet port.

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. The donor roll includes a section of increased diameter spaced away from the latent image, and the electrode wire is disposed in sliding contact with the section of increased diameter to obtain a consistent spacing from the main length of the donor roll.

Abstract: A remote driver board suitable for creating electrical interconnections in a substantially wireless electrical apparatus such as a electrophotographic apparatus. A series of parallel conductors extend the length of one side of the board, and along the other side is disposed a modular connector and a switching device, such as in the form of an integrated circuit, for controlling connections between the parallel conductors to other electrical devices in the system through the modular connector.