Abstract: In an apparatus for exposing a set of discrete locations on a photosensitive surface, such as an electrophotographic printer, a scanner transmits a light beam along a scan path onto the photosensitive surface. An optical element, interposed in the scan path between the photosensitive surface and the scanner, defines a plurality of apertures therein where no more than one aperture is disposed at any location along a linear dimension of the optical element parallel to the scan direction. The light beam transmitted through each aperture exposes a discrete location on the photosensitive surface.

Abstract: A fiber optic system is used in a laser ROS scanning system to generate a start of scan signal. In one embodiment, a single optical fiber is positioned at the beginning of a scan line sweep. The fiber transmits a portion of a scan beam energy to a photodetector located on a main electronics system board. The photodiode generates an output signal which is sent as an input to a high speed comparator. A second input to the comparator is a second signal derived from said first signal but having a lower amplitude. The comparator compares two wave forms and generates a sharp electrical transition at the precise time the two wave forms cross which, in preferred embodiment, occurs when the first wave form amplitude level falls to about 1/2 of maximum. The comparator output is used to initiate the SOS signal of a laser diode ROS.

Abstract: The present invention is an apparatus for eliminating differential scanline bow in a raster output scanner (ROS) printing system. The apparatus employs a field lens device at the output of a pre-scanning optical assembly in order to direct the laser beams toward the scanning surface, or facet, at a right angle to the scanning surface, thereby eliminating a source of scanline bow.

Abstract: A electrophotographic printing apparatus comprises a first laser source, emitting a first beam in a first direction, and a second laser source, emitting a second beam in a second direction. A roof mirror directs the first beam and the second beam along a third direction, so that the two beams have a substantially coincident virtual source point.

Abstract: A fiber optic system is used in a laser ROS scanning system to generate a start of scan signal. In one embodiment, a single optical fiber is positioned at the beginning of a scan line sweep. The fiber transmits a portion of a scan beam energy, directed non-axially into the fiber entrance to a photosensor. The photosensor generates an output response which is processed to initiate the SOS signal. The fiber entrance face is formed so that the beam, entering non-axially, is either reflected internally along the fiber axis or first refracted and then reflected along the fiber axis. Dual fiber embodiments are also presented which detect and transmit non-axially incident scanning beams.

Abstract: An optical element for the selective scan line skew correction in a raster output scanner (ROS) of an electrostatographic printer. The optical element includes a chamber having a volume defined by parallel surfaces in substantially parallel planes containing a liquid crystal material having a variable index of refraction as a function of voltage applied thereacross. An inhomogenous electric field is generated through the liquid crystal material to produce a refractive index gradient along substantially perpendicular planes in the optical element. The ROS includes a control and feedback system coupled to a variable voltage source for applying a variable biasing voltage across the optical element to control the variable index of refraction of the liquid crystal material for selectively correcting scan line skew.

Abstract: An optical element for the transmission of a light beam moving in a scan direction in an electrophotographic printer provides real-time feedback to monitor the motion of the scan. A member elongated in the scan direction is adapted for the transmission of light therethrough in a direction transverse to the scan direction. An optical pattern along a portion of the member in the scan direction includes at least one surface for the non-transmission of light passing transverse to the scan direction.

Abstract: A conformable drive system for transporting a surface, such as an imaging surface, along a predetermined path of travel. An intermediate drive assembly, including an endless tape loop, operatively associated with a rotational drive source is provided. The endless tape loop is driven by the rotational drive source such that the tape loop, when positioned in frictional contact with the surface to be transported, induces transport movement of the surface. The tape loop includes a nonelastic support layer for preventing the tape loop from stretching, and also includes a frictional contact layer for providing substantial frictional forces between the tape loop and the surface being transported. The configuration of the conformable drive system provides sufficient contact pressure for imparting a substantially constant velocity vector to the transported surface for maintaining substantially constant speed control of the transported surface.

Abstract: A system for transporting an imaging surface in an electrostatographic printing apparatus. The imaging surface is transported along a predetermined path in a process direction of travel while being maintained in both lateral and skew alignment via a selectively controllable drive system for inducing differential or non-differential transport motion of the imaging surface. A control system is also provided for selectively operating the drive system to compensate for detected lateral or skew misalignment of the imaging surface.

Abstract: An apparatus is useful for positioning a substrate having an aperture therein movable in a process direction. A photodetector is disposed adjacent a first side of the substrate, in a position intersecting a path of the aperture along the process direction. A first light source point and a second light source point are positioned whereby, when the aperture is disposed between the first light source point and the second light source point and the photodetector, direct light from both the first light source point and the second light source point is capable of being detected by the photodetector. A condition detector detects a condition in which light of substantially equal intensity from the first light source point and the second light source point is detected by the photodetector.

Abstract: An ionographic printing system including an imaging member with a charge retentive surface on which a latent image may be formed; a printhead including a source of ions, means for moving ions from the source to the charge retentive surface in a continuous stream, and means for modulating the stream in accordance with a desired image; and in which a projection field between the charge retentive surface and the printhead tends to focus ions in a manner reducing spread in directions parallel and anti-parallel to the process direction, there is provided means for defocusing and slightly repositioning the ion stream including an additional pair of electrodes arranged adjacent to the ion stream and an A.C. voltage source with time dependent bias, to apply an A.C. field across the ion stream at a frequency selected to sweep the ion stream in two directions parallel and anti-parallel to the process direction of the device.

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 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 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: 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: A method employing multiple pulses per pixel to reproduce an image. A motion detector detects movement of an image receptor relative to a row of reproduction elements. The motion detector generates multiple pulses for each movement of the image receptor corresponding to a pixel dimension. Each pulse from the motion detector enables each reproduction element for a predetermined time.

Abstract: A belt steering roller mechanism for active steering correction of an endless belt, including a shaft having a longitudinal axis and a deformable roller having a fore end and an aft end and a predetermined diameter. The roller is rotatable about the shaft and has a body including a plurality of longitudinally extending rigid members located near the outer diameter of the roll separated by a plurality of longitudinally extending deformable sections. The body may be elastomeric or may be rigid with flexible hinges to provide differential lateral velocity of an outer circumferential surface of the roller. At least one flange plate is located against one of the fore end and aft end and is flexibly held on the shaft by a flexible coupling. Upon a corrective force being applied to the flange plate by an articulating mechanism, the longitudinally extending rigid members are laterally displaced in a cyclic fashion by the flange plate.

Abstract: The device has a glass-like substrate of variable configurations. Three layers of thin paint-like material is uniformly deposited upon the substrate. The first and third layers are an electrically resistive material, the second layer is a dielectric material. An air gap, descending through all three layers, runs the width of the device. Thus, in operation, energizing the resistive layers in varying configurations of potentials will strike a gaseous plasma in a narrow gap thus ionizing air molecules. In the preferred arrangement, a high potential is applied to the first or innermost resistive layer to strike a plasma and generate ions. A fraction of these ions flow outwardly through the gap past the third or outer resistive layer and may be accelerated to the charging charge retentive surface.

Abstract: In an imaging device having a belt supporting image on an image supporting surface and moving along an endless path in a process direction, an exposure device for forming images on the image supporting surface, an arrangement is provided to derive information about belt position with respect to the exposure device. The belt is provided with at least one fiducial opening or target at a belt edge, and a sensor is arranged with respect to the belt and the fiducial opening, to sense illumination directed through the fiducial opening. An illumination source is provided at a fixed position with respect to the exposure device and the sensor to directing illumination to the sensor, when the fiducial opening is aligned with the sensor, including at least two independently detectable illumination sources arranged along a cross process direction. Belt position with respect to the exposure device is then determined from the amount of occlusion of one of the first and second independently detectable illumination sources.

Abstract: A print head for an ionographic printing system, including a multiple pluralities of modulation electrodes for modulating an ion stream generated by the print head, and multiple correction electrodes. Each correction electrode is located in proximity to one of the pluralities of modulation electrodes.