Abstract: A light collector for directing light to a concentrated area on a target surface such as for use with a linear LED array used as an erase lamp in an electrophotographic printer. The collector includes a compound cylinder lens supported by a pair of reflecting members. The reflecting members reflect light rays from the LED array to the cylinder lens. The cylinder lens includes a lower surface for capturing the reflected light rays and a tongue extending from the lower surface for capturing light rays directly from the LED array. The cylinder lens directs and concentrates the captured light rays in a narrow line on a target surface.

Abstract: A low ink sensing system is combined with an ink cartridge detection system to enable a more efficient ink jet printer. An ink container which supplies ink to an associated printhead is modified by the incorporation of two light directing elements, in the preferred embodiment, a faceted prism and a roof mirror, into a transparent wall of the container housing. The cartridge, comprising the ink container and associated printhead, is mounted on a scan carriage. Periodically, the carriage is conveyed to a sensing station comprising a pair of light sources and a commonly used photosensor. A first light source is energized and a beam of light is directed to a location where the roof mirror, would be positioned if the cartridge is present. If the cartridge is absent, lack of a reflected return signal is sensed, indicating a cartridge has not been inserted. Print operation is halted until a cartridge is inserted.

Abstract: A sensor system for measuring physical properties of paper. The paper property sensor system includes a surface and a diaphragm opposed to each other. The small diaphragm includes a first pair and a second pair p-type piezoresistors. Each piezoresistor of the first pair has a longitudinal axis and is located perpendicular to and very close to one of the long edges of the diaphragm. Each piezoresistor of the second pair has a longitudinal axis and is located between and parallel to first pair of piezoresistors, and away from the short edges of the diaphragm. Coupling the first pair of piezoresistors with the second pair via a Wheatstone bridge produces a voltage representative of the shear force exerted by a sheet.

Abstract: A sensor detects the presence of opaque and transparent copy substrates in a substrate transporting path and includes an LED disposed near the transporting path for projecting light toward a reflector on the opposite side of the media transport path and a phototransistor located relative to the LED and reflector to receive light reflected from the reflector which is periodically interrupted by substrates within the transporting path to provide an output proportional to the light received from the LED via the reflector. The operating range of the phototransistor has a linear portion and a saturated portion. A control, electrically connected to the sensor, adjusts the phototransistor to maintain the output signal in the linear portion of the operating range. The sensor is tilted at an angle with respect to the horizontal of a copy substrate to be able to detect transparencies.

Abstract: A system for transporting a sheet of material including an actuator, a position sensing system, and a tactile sensor system. The actuator imparts a known force to a sheet, moving it through to the position sensing system, which measures the sheet velocity at various points. Afterward, the sheet moves through the tactile sensor system, which determines the coefficient of friction of the sheet. Given these quantities, a controller can determine the mass of the sheet, which can be used alter the performance of the sheet transport system.

Abstract: A device for diagnosing the condition of copy substrate sensors including a transparent test document supposing a plurality of stripes of predetermined optical density The stripes are arranged in descending optical density about a stripe of maximum density and a transporter conveys the test document into communication with the optical path of each sensor. Circuitry responds to the stripes of predetermined optical density to provide a timing pulse of response of each sensor to the test document. The timing pulse is a. digital step pulse identifying the range of optical sensitivity each sensor and the step pulse represents a given set of stripes that provide a detector signal exceeding a threshold value.

Abstract: A system for measuring the mass of a sheet of material including an actuator, a position sensing system, and a tactile sensor system. The actuator imparts a known force to a sheet, moving it through to the position sensing system, which measures the sheet velocity at various points. Afterward, the sheet moves through the tactile sensor system, which determines the coefficient of friction of the sheet. Given these quantities, a controller can determine the mass of the sheet, which can be used alter the performance of a reproductive machine. A second embodiment of the mass measuring system includes an actuator, a position sensing system, and a subsystem for eliminating friction. The actuator applies a force to a sheet to move it into and through the subsystem. The position sensing system incorporated in the subsystem senses the acceleration of the sheet. Given this quantity, a controller can determine the mass of the sheet.

Abstract: A maintenance system for an ink jet printer of the type having a full width array printhead has a movable carriage with a droplet sensor and a nozzle recovery device. As the carriage moves along the length of the printhead, each nozzle checked, one at a time, by the droplet sensor for the presence or absence of an ejected droplet and if the droplet has the correct directionality. Any problem nozzle is identified during a single traversal of the carriage across the printhead, and during a second traversal, the identified problem nozzles have a recovery operation performed on them such as being cleaned to remove any dried ink or other contaminating particles or being primed in the case of a clogged nozzle. The problem nozzles which have had a recovery operation performed on them and checked again by the droplet sensor is required for the entire array of nozzles, and ink is conserved since only predetermined nozzles are printed.

Abstract: An optical element uniformly distributes radiant energy on a target surface, such as for discharging an area of a photoreceptor in a xerographic printer, or for applying infrared energy to dry an ink-jet image. A cylinder lens collimates light beams from a light source and directs the collimated light beams to a preselected area on the target surface. First and second refractive portions, each attached to and extending parallel to the cylinder lens, totally internally reflect light beams from the light source and direct the light beams reflected therein to the target surface.

Abstract: An infrared densitometer which measures the diffuse component of reflectivity as marking particles are progressively deposited on a moving photoconductive belt. Collimated light rays are projected onto a test patch including the marking particles. The light rays reflected from the test patch are collected and directed onto a photodiode array. The photodiode array generates electrical signals proportional to the total flux and a diffuse component of the total flux of the reflected light rays. Circuitry compares the electrical signals and determines the difference to generate an electrical signal proportional to the specular component of the total flux of the reflected light rays. Additional circuitry adds the electrical signals proportional to the total flux and the diffuse component of the total flux of the reflected light rays and compares the result of the summed signal to the specular component to provide a total diffuse signal for controlling developed mass.

Abstract: A sensor having a shutter mounted upon a shaft for rotation within a housing in opposition to a light path between an LED and photodetector is described. A potion of the shaft extends outside the housing connected to an elongated arm. A runner secured to the elongated arm, engages a moving photosensitive surface and deviations of the edge position of the photosensitive surface rotate the shutter in relation to the light path between the LED and photodetector for tracking the edge position of the moving photosensitive surface by providing signals representing shutter position.

Abstract: An apparatus and method for reliably monitoring the position of a radiant energy beam, for example, a scanning laser beam such as that produced by a raster output scanning system to expose a photoresponsive member, where the beam traverses the surface of a photoreceptive member at a high rate of speed. The apparatus, which includes a lateral-effect photodiode, is also capable of signaling when the radiant energy beam traverses a specific location. The apparatus may also be used to determine the relative intensity of the radiant energy beam, thereby significantly reducing the space and expense necessary to monitor the radiant energy beam by combining multiple sensing operation in a single apparatus.

Abstract: An apparatus for positional tracking a moving photoconductive belt and adjusting an imager in an electrophotographic printing machine to correct for alignment errors when forming a composite image. Registration errors are sensed by developing an appropriate set of target marks, detecting the target marks, and controlling the position of the imager.

Abstract: An apparatus and method for reliably monitoring the position of a radiant energy beam, for example, a scanning laser beam such as that produced by a raster output scanning system to expose a photoresponsive member, where the beam traverses the surface of a photoreceptive member at a high rate of speed. The apparatus, which includes a lateral-effect photodiode, is also capable of signaling when the radiant energy beam traverses a specific location. The apparatus may also be used to determine the relative intensity of the radiant energy beam, thereby significantly reducing the space and expense necessary to monitor the radiant energy beam by combining multiple sensing operation in a single apparatus.

Abstract: A printing machine in which magnetically permeable marking particles develop a latent image recorded on a photoconductive member. A read head is positioned on the opposite of the photoconductive member to detect magnetic field intensity effects produced by the leading edge and the trailing edge of the marking particles on the characters recorded. The detected signals are used to control the magnetic quality of the developed image.

Abstract: An apparatus and method of adjusting an imager in an electrophotographic printing machine to correct for registration errors when forming a composite image. Registration errors are sensed by forming one or more target lines on the photoreceptor surface, detecting the center of the lines and controlling the operation of the imager in response thereto. In one embodiment, four LED print bars form a composite color image in a single pass. A photosensor is placed beneath the print bars; a narrow target line is formed on the belt surface a few scan lines before the start of an exposure frame. The center of the line is detected by circuitry connected to the sensor output which produces a signal corresponding to detection of the center of the target line. This output signal is generated for each of the three downstream print bars and a signal is applied to each print bar to start the image exposure sequence in registration with first image exposure.

Abstract: A magnetic ink monitoring system is provided including a reader which outputs an electrical signal representative of a magnetic flux, a storage mechanism which stores an integral representation of a signal from a standard magnetic ink display, and a comparator operatively connected to the read means and the storage means to compare an integral signal of the electrical signal of the magnetic ink display to the integral representation of a signal from a standard magnetic ink character.

Abstract: A method and apparatus is provided for lateral registration of image exposures on photoreceptive belts subject to lateral deviation from linear travel. In one embodiment, a plurality of Raster Output Scanner (ROS) imagers in a digital color printer are positioned so as to form successive images on the surface of the belt. A plurality of split cell photodetectors are positioned beneath the belt, one each associated with each of the ROS imagers. An aperture is formed in the belt in a non-image area, but in alignment with the detectors. Scan lines from each ROS unit are periodically visible through the aperture and illuminate the photodetector. The outputs from each of the photodetector photosites are compared and lateral belt movement errors thereby identified. Appropriate correction signals are generated to maintain the correct lateral registration.

Abstract: A Raster Output Scanner (ROS) color printer is formed by providing several ROS imagers adjacent image exposure locations of a photoreceptor belt. Each ROS imager forms a separate color image in response to video input signals with each color image superimposed in registration over the previously formed images. Registration in the process direction is enabled by a quad cell photosensor whose output is continually compared to determine whether process registration deviations from a previously established position are necessary. Correction signals are generated in an iterative fashion until a preselected process registration position is re-established. The quad cell detector is also used for a second function; to produce the start and end of scan signals which enable image registration in the cross-process direction.

Abstract: The present invention is directed to a precise method of registering plurality of imaging stations, so as to form sequential images on a photoreceptor belt in a single pass. A belt hole is formed in the photoreceptor belt, outside the image area, but within the scan of the imager scan line. The scan line is sequentially swept in a transverse direction across the width of the belt. As the leading edge of the belt hole advances into the sweeping beam, a plurality of beam sweeps will occur while the leading edge is moving through the sweep area. Due to the gaussian illumination of the scanning beam, the exposure at the belt edge gradually increases to a maximum point coinciding with the maximum illumination of the scanning beam. A detector is placed beneath the belt to provide a signal representing the exposure level of each scanning beam which crosses the leading edge of the advancing belt hole. The detectors produce a current output representative of the exposure level.