Abstract: A light emitting diode based exposure station (and electrophotographic marking machines that use such exposure stations) that requires only a small amount of photoreceptor waterfront (space). The small waterfront requirement is achieved using a gradient index lens array that transmits focused light onto the photoreceptor with a total conjugate that is sufficient to permit the widest part of the light emitting diode based exposure station to be displaced sufficiently far from the photoreceptor that other printing machine devices can be disposed between the widest part of the exposure station and the photoreceptor. The increased total conjugate is achieved using a gradient index lens array having longer rods and/or wider rods.

Abstract: A raster input scanner, and a reproduction system that uses that input scanner, having multiple depths of focus. The raster input scanner includes a light source for emitting light toward an image bearing member and at least two lens arrays, with the ability to selectably position any one lens array in optical conjugate relationship between the image bearing member on a transparent platen and a photosensor array. One of the lens arrays has a first depth of focus, while the other lens array has a second depth of focus that is different than the first depth of focus. Beneficially, the input scanner responds to an operator selection of which depth of focus is to be used to image a given image bearing member.

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: 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: An image bar printing system, which, in a preferred embodiment, utilizes a plurality of LED arrays to provide a plurality of color images. The print bars are used in conjunction with a plurality of gradient index lens arrays which optically couple and focus the LED outputs onto a photosensitive surface. In order to maintain image-to-image registration, out of spec deviations in active write length of the image bar and scan line bow are identified and compensated for by selective deformation of one or more lens arrays in a specified manner. The lens deformation serves to reorient the position of certain of the lens elements, redirecting the transmitted LED outputs so as to shorten or lengthen the active write length, or to eliminate bow in the scan line.

Abstract: REaD(Recharge Expose and Develop) electrophotographic printing using additive color toners and inhibited image on image development. Inhibited image on image development is achieved by setting the exposure set points such that exposure losses incurred when imaging through previously developed toner reduces the electrostatic potential for developing over the developed toner, by using a DC corona system during recharging so as to enhance the voltage drop across the previously developed toner(s), and/or by increasing the developed toner mass to increase the thickness of the dielectric properties of the developed toner.

Abstract: A system for concurrently imaging the first and second sides of different sequential duplex documents in alternating image lines alternating between the first and second imaging stations. This system is shown in a system for imaging both of the first and second opposing sides of duplex documents with higher productivity, with a generally "V" shaped low profile document sheet feeding path with first and second arms merging at a base position having a document reversing system, for sequentially feeding documents from an input tray through the first arm to the base position, and then back through the second arm to an output tray. A first imaging station is in the first arm for imaging the first sides of the documents, and a second imaging station is in the second arm for imaging the second sides. Both imaging stations have a simple, partially shared fixed elements optical system mounted entirely inside the document path, which can share a single electro-optical digital imager.

Abstract: A digital scanning system for scanning a document includes a full width array having two sets of color sensitive photosites, each set of photosites being sensitive to a different color of light and a backdrop portion. The backdrop portion is colored such that the backdrop portion appears nearly black to one set of color sensitive photosites and appears nearly white to a different set of color sensitive photosites. the scanning system further includes a light source, a document edge detection circuit operatively connected to the set of color sensitive photosites which perceive the backdrop portion as being nearly black, and an image processing circuit operatively connected to the set of color sensitive photosites which perceive the backdrop portion as being nearly white.

Abstract: A system for imaging both of the first and second opposing sides of duplex documents with higher productivity, with a generally "V" shaped low profile document sheet feeding path with first and second arms merging at a base position having a document reversing system, for sequentially feeding documents from an input tray through the first arm to the base position, and then back through the second arm to an output tray. A first imaging station is in the first arm for imaging the first sides of the documents, and a second imaging station is in the second arm for imaging the second sides. Both imaging stations have a simple, partially shared fixed elements optical system mounted entirely inside the document path, which can share a single electro-optical digital imager. The duplex documents are not inverted, yet are returned to the output tray in the same orientation as the stack in the overlying input tray. Compatible simplex document copying can also be provided.

Abstract: In an optical system, a lens array comprises a plurality of gradient index lenses arranged in a plurality of rows. The lens array is aligned with an image bar having a plurality of pixel rows in such a manner that each pixel row in the image bar is symmetrically arranged with respect to lens rows having fields of view encompassing the pixel row.

Abstract: The invention is directed to a document reproduction system which includes an improved apparatus for imaging both sides of a duplex document while also providing for simplex side only imaging. A document feeder, operating in a constant velocity transport mode, moves a document to be copied along a continuous path from a feed tray to a deposit tray. Two illumination and scanning stations are positioned adjacent two locations of the path of the document travel, each scanning station adapted to scan one side of the document, either simplex or duplex. The scanning station associated with scanning the simplex side of the document projects line images of the scanned document along an optical path onto a light sensitive image medium. In a first embodiment, the projection device is a linear gradient index lens array and the light sensitive member is a linear sensor array.

Abstract: An imaging system is disclosed which incorporates a gradient index lens array to transmit focused light onto an image medium with increased Depth of Focus (DOF) and no loss of radiometric efficiency. The lens array is first constructed so that its exit pupil is generally symmetrical. This first step increases the radiometric efficiency of the lens array relative to prior art lens arrays. In a second step, the DOF is increased by reducing a quantity n.sub.o .sqroot.AR which is associated with the lens, n.sub.o being the axial refractive index of the fibers comprising the lens array, .sqroot.A being the gradient index constant of the material comprising the lens array and R being the radius of the individual optical rods, As this quantity is reduced, the DOF increases consistent with a trade off of reduced radiometric efficiency. Since the efficiency was initially increased from some optimum value, the DOF can be increased until the desired radiometric efficiency level is reached.

Abstract: A copier with an anamorphic magnification imaging system is provided with improvements which enable increased resolution of exposed line images at a photoreceptor. The improvement relates to reducing the effective imaging aperture through which the images is projected onto the surface of a photoreceptor. In one embodiment, a gradient index lens array which transmits light reflected from illuminated scan strip on a document platen is provided with two blockers attached to opposite sides of the lens array. Each blocker element has a blocking end which projects into the optical path and blocks a portion of the light that would otherwise be transmitted along the optical path. The effect of the two blockers is to form an effective imaging aperture having a width less than 1mm, in the preferred embodiment about 0.4mm. This narrow imaging width enables a high resolution output image.

Abstract: A xerographic printer especially suitable for printing copies of oversized original documents is enabled by staggering a plurality of image bars in optical alignment with a linear projection means such as gradient index lens arrays which are tilted at a preferred angle. The image bars are selectively addressed in response to digitized bit-mapped data inputs representing the document information. The modulated light outputs from the bars are transmitted as focused lines on the surface of the photoreceptor. The printer includes illumination lamps and a lamp aperture which parallels the staggered image bars. Further, a multi-function copier/printer is realized by combining a variation of the xerographic printer with a conventional imaging system for copying a document.

Abstract: The present invention relates to a color printer which forms multiple latent images on the surface of a belt type photoreceptor in a single pass. The invention enables the placement of imaging stations on both a tensioned and non-tensioned side of the belt. On the non-tensioned, an asynchronous line at a time printer such as an LED print bar is used to form the latent image in response to video data signals. On the tensioned side of the belt, either synchronous type imagers, such as laser ROSs or asynchronous imagers such as LED print bars may be located to form the latent image. The leading edges of each image frame are registered according to known methods. Each scan line within an image frame is registered by comparing the belt speed beneath each of the imagers and generating a correction signal to the asynchronous print bar.

Abstract: A printing machine in which two electrostatic latent images are recorded on a photoconductive member. One of the latent images is a charged area latent image with the other image being a discharged area latent image. A magnetic developer unit develops the charged area latent image with black toner particles. A non-magnetic developer unit develops the discharged area latent image with toner particles of a color other than black. The toner particles from both latent images are transferred substantially simultaneously to a sheet and fused thereto forming a color high lighted document.

Abstract: A printing system operating in a charged area development environmental utilizes a high resolution image print bar in cooperation with a low resolution image discharge bar to expose a charged surface of a photoreceptor with a minimum of stress being applied to the high resolution bar. The high resolution bar is addressed from an image data source so as to expose areas of the photoreceptor which correspond to informational areas of the image being printed. The low resolution bar is addressed from the same data source so as to discharge the photoreceptor surface in non-informational areas such as background areas and interimage areas. In a preferred embodiment, both the high and the low resolution bars are LED arrays located in a common exposure station.

Abstract: The resolution of an LED print bar used in printing applications is modified by optically coupling the print bar, in a preferred embodiment, to a two row, square ended, reduction enlargement gradient index lens array. The lens array is modified to have a radiometric speed suitable for printing applications (f/3 or faster) with a total conjugate long enough to maintain optical quality at full field. In a preferred embodiment, a nominal 480 spi print bar is coupled to a modified 0.80X R/E lens array to provide a resolution in an image plane of 600 spi. Other embodiments are described which utilize a plurality of print bars with a combination of unity magnification gradient index lens array in conjunction with a modified R/E lens array.

Abstract: A compact machine architecture is realized by combining the functions of copy sheet feeding and stacking into one integral apparatus. The apparatus is initially completely filled with copy sheets to be moved into the transfer/fusing area of a copier/duplicator machine. A vertically translatable stacker tray is positioned above the copy sheet input and is moved downward in vertical synchronism with copy sheets being fed from the input stack. A paper feed roller, attached to the bottom of the tray, continually feeds the top sheet from the input supply. As the input sheet stack is consumed, the output (feed) copies are deposited onto the stacker tray. As operation continues the supply stack is depleted while the finished stack increases, but the overall volume occupied by the copy sheets remains the same. Since there is no "empty" volume in the apparatus, the size and cost of the unit is greatly reduced.

Abstract: A multiple diode laser array used in a ROS scanning system is modified to reduce the effects of undesirable spatial exposure variation at the surface of certain type of layered, semi-transparent photoreceptors. The spatial absorption variation is later manifested as a "plywooding" pattern formed on output prints derived from the exposed photoreceptor. The laser array is modified to form a merged scanning beam at the photoreceptor surface of two or more diode outputs, each output operating at a different wavelength than the other. In one embodiment, a plurality of diodes, each at a different wavelength, are sequentially addressed, and an image of each diode is scanned across the photoreceptor which results in an exposure distribution that would be similar to that formed by an incoherent beam.