Abstract: An imaging system having a raster output scanner that produces high quality scan lines comprised of evenly spaced pixels. The raster output laser device is modulated in accordance with a variable frequency pixel clock that is derived from a high frequency oscillator using a dual modulus programmable divider that is controlled by a state machine. In turn, that state machine is controlled by information stored in a memory. The variable frequency pixel clock compensates for scan line nonlinearity, polygon facet errors, and/or scan line magnification.

Abstract: A substrate sensor system having a light source for radiating light toward a substrate position, a light sensor system positioned to receive light transmitted or reflected at the substrate, a lens that images the light transmitted or reflected at the substrate onto the light sensor system, and a telecentric stop between the lens and the light sensor system. Beneficially, such substrate sensor systems will include an electrical circuit that produces position information regarding the position of a substrate and/or the position of an image on a substrate.

Abstract: Raster output scanners having piezoelectric-activated lens movers comprised of a mounting base, an electrically operated piezoelectric element connected to the mounting base, a flexible linkage having a lens mount, and a lens attached to the lens mount. The flexible linkage includes flexible arms that can flex in the predominate direction of motion of the piezoelectric element, but that are substantially rigid in another direction. The flexible linkage is mounted such that the flexible arms bias the lens toward the piezoelectric element. Expansion and contraction of the piezoelectric element, combined with the bias of the flexible arms cause the lens mount and its attached lens to follow the expansion and contraction of the piezoelectric element. The rigidity of the flexible arms hold the lens in the proper focal plane. Beneficially, the piezoelectric element is driven so as to compensate for scan line position errors.

Abstract: A substrate feeding system, and printers that use such feeding systems, that includes a feed roll and a retard roll that form a nip, a nudger roll for advancing a substrate from a substrate stack toward the nip, and an entrance guide between the nudger roll and the nip. The entrance guide has a contact surface that forms an angle of more than 100.degree. with the direction of motion of the substrate. The entrance guide further including a top section over which the substrate moves as it advances into the nip. The entrance guide is beneficially pivotally mounted such that when a retard roll is removed the entrance guide pivots out of the way, and such that when a retard roll is in place the entrance guide moves into position.

Abstract: A rapid warm-up fuser roller (and fusers and marking machines that use such a fuser) comprised of a metallic cylindrical core, a thermally and electrically insulating layer of volume graft over the metallic core, a resistive heating layer over the insulating layer, and electrical connections to the resistive heating layer such that electrical current passing through the electrical connections flows through the resistive heating layer in a direction that is substantially parallel to the axis of the metallic core. The electrical current causes the resistive heating layer to heat while the insulating layer of volume graft enables rapid warm-up of the roller.

Abstract: An apparatus for forming an image comprising a substrate with a plurality of high voltage transistors on the substrate. The transistors include a source electrode, a drain electrode and a gate electrode. Each transistor switches a marking potential of several hundred volts between the source and drain by a gate potential of at least an order of magnitude lower than the source to drain potential. There are a plurality of high voltage capacitors on the substrate. One of each capacitor is connected to one of the drain electrodes and each capacitor stores a charge potential approximately equal to the marking potential. The charge potential on each capacitor controls the forming of the image. A first data input on the substrate selectively loads a gate potential on gate the electrodes. A second data input located on the periphery of the substrate selectively loads a source potential on the source electrodes.

Abstract: A raster output scanner assembly having a first laser source for producing first and second laser beams, and a second laser source for producing third a fourth laser beams. The first and second laser beams are directed to a first rotating, multifaceted polygon while the third and fourth laser beams are directed to a second rotating, multifaceted polygon. The first polygon reflects the first and second laser beams onto a moving photoreceptor while the second polygon reflects the third and fourth laser beams onto the photoreceptor. The spots produced by the various laser beams are interlaced such that the scan line produced by the third laser beam is between the scan lines produced by the first and second laser beams, while the scan line produced by the fourth laser beam is adjacent the scan line produced by the second laser beam.

Abstract: Correcting color banding problems resulting from facet-to-facet jitter in a color imaging device having a multifaceted polygon are corrected by starting each color separation using the same facet. This facet synchronization has been shown to reduce the objectionable color banding. Imaging offsets that result from either advancing or retarding the exposure of a latent image such that the latent image begins with the same facet as other latent images are compensated for using a rotating cylinder mirror whose rotation is controlled by a piezoelectric element.

Abstract: A color electrophotographic printer that prepares a composite toner image for transfer by exposing an image area containing the composite toner image to an erase lamp and then running the composite toner image by an AC scorotron.

Abstract: An apparatus for advancing at least two different types of substrates from a moving surface to a fusing station is disclosed. A constant speed transport positioned to receive the substrate from the moving surface advances the substrate to the fusing station. An air moving device moves air such that air pressure induces a drive force on the substrate on the transport. A sensor generates a first signal when the substrate is of a first type and generates a second signal when the substrate is of a second type. The air moving device induces a first drive force when the sensor generates the first signal and induces a second drive force when the sensor generates the second signal.

Abstract: Correcting motion quality induced color banding problems resulting from photoreceptor motion defects in a color imaging device having a laser based multifaceted polygon and a rotating cylindrical mirror whose rotation is set by a controlled rotation inducing element. A motion sensor senses the motion of the photoreceptor. Based upon motion errors a controller either advances or delays the production of a latent image. The controller further controls the rotation inducing element, beneficially a piezoelectric element, such that a latent image is produced in a predetermined location. When multiple latent images are produced, the controller beneficially causes the latent images to be properly registered.

Abstract: Operation of a developer so as to achieve reduced scavenging and reduced direct contamination when using a hybrid developer. A hybrid developer is operated in three modes. The first mode is normal operation in which the developer operates as in the prior art. The second mode is an unloaded standby mode wherein toner is not on the developer's donor roll and wherein the developer's bias potentials are selected to reduce scavenging. The third mode is a loaded standby mode wherein toner is on the developer's donor roll and wherein the developer's bias potentials are selected to reduce direct contamination.

Abstract: REaD electrophotographic printing using additive color toners. Toners that are non-transmissive to exposing light are developed using inhibited image-on-image printing. Then, the photoreceptor is exposed to produce a latent image for a toner that transmits the exposing light. Finally, the latent image for a toner that transmits the exposing light is developed.

Abstract: A rapid warm-up fuser belt (and fusers and marking machines that use such a fuser belt) comprised of a conductive substrate having a resistive heating layer on one side and a release layer on the other side. The fuser belt further enables an electrical contact to the conductive substrate. Electrical current passing through the conductive substrate and through the resistive heating layer, causes the resistive heating layer to heat. The fuser belt can either provide for a direct electrical connection to the resistive heating layer, or it can include a semiconductive layer on the resistive heating layer that improves the electrical connection to the resistive heating layer.

Abstract: A system for removal of toner particles from a transfer support member surface without the necessity of an independent toner recovery system. A cleaning blade on the transfer support member collects and accumulates residual toner particles. When a non-image area on the photoconductor passes beneath the blade, the blade is spaced from the photoconductor and a reverse bias applied to the transfer support member so that the accumulated particles are transferred to the photoconductive surface. Subsequently, the cleaning system associated with the photoconductive member removes these toner particles.

Abstract: Raster scanner assemblies, and machines which use such raster scanner assemblies, which produce spots having a variable spot dimension. Raster scanner assemblies according to the present invention include an electronic subsystem which produces both image data and a spot size control signal, a laser assembly which produces a polarized laser beam having a beam with a first dimension and which is modulated in accord with the image data, a variable aperture assembly which changes the first dimension of the laser beam, a rotating polygon having a plurality of facets sweeping the laser beam in a sweep plane, and a scan lens for focusing the laser beam onto an image plane. The variable aperture assembly beneficially includes both a liquid crystal cell, which receives the laser beam and the spot size control signal, and a polarizing filter.

Abstract: A system of mounting a raster output scanner relative to a photoreceptor such that deskewing, focusing, and pitch adjustment of the aerial image are possible. A spring isolated ROS assembly having at least two ROS arms attaches to a backer bar assembly that locates the position of the photoreceptor. The backer bar assembly and the ROS assembly connect at one end using a ball and socket and at the other end using a ball and fork such that the center line of the balls form a scan line plane. The ball and socket form a reference connection at one end. At the ball and socket end the photoreceptor backer bar has a mounting arm that is flexible in one plane but rigid in a perpendicular plane. A deskew mechanism, beneficially a motor driven cam, flexes the backer bar mounting arm as required to deskew the scan line.

Abstract: Color banding resulting from facet-to-facet jitter in a color imaging device having a plurality of multifaceted polygons is reduced by matching the facets of the various polygons such that the composite image produced by the matched facets result in minimal color banding. The latent images are registered by starting each latent image with a selected "starting" facet such that the matched facets trace corresponding scan lines. Imaging offsets that would result from either advancing or retarding the exposure of a latent image such that the latent images begin with the correct facet are compensated for by moving a rotating cylinder mirror in each polygon such that the latent images are registered. Moving of the cylinder mirror is beneficially achieved using a controlled piezoelectric element.

Abstract: Registering a first image on a first side of a substrate with a second image on a second side. A motor driven document transport advances a substrate to a transfer station that transfers the first image onto the substrate. The substrate is then inverted and the document transport moves the inverted substrate back to the transfer station to receive a second image. A sensor detects a leading edge and a trailing edge of the substrate, while an encoder operatively connected to the motor produces a predetermined number of pulses per revolution. A counter counts the number of encoder pulses between the leading edge and the trailing edge. The controller then determines the width of the substrate from the number of counted encoder pulses and from the distance the substrate advances per encoder pulse. The controller then controls the document transport to position the substrate at the transfer station such that the second image is registered with the first image.

Abstract: A Recharge-Expose-and-Develop Image on Image color electrophotographic printing system in which the photoreceptor is recharged between development of one color of toner image and the subsequent exposure for a second color latent image by first being sprayed with opposite sign ions to reduce the photoreceptor potential and then being charged with correct sign ions to recharge the photoreceptor to a desired potential.