Abstract: A process cartridge (14) is comprised of a process housing (138) and a transfer housing (148). The process housing (138) contains a photoconductor drum (16) and an intermediate transfer belt (160). The transfer belt (160) is operable to receive multiple images from the photoconductor drum (16) until a composite image is formed on the transfer belt (160). Thereafter, the transfer housing (140) is titled into contact with a backup roller (162) in the process housing (138) through a transfer roller (208). The nip between the two rollers is then operable to feed a piece of paper therethrough and transfer the composite image from the transfer belt (160) to the paper. Alignment pins (114) and (116) on the upper end of the housing and lower alignment pins (118) and (120) on the lower end of the process housing (138) are provided to fit in the guide rails (110) and (112), which provide an alignment function.

Abstract: An electrophotographic printing device having an arcuate photoconductive member (12) includes a flat screen member (32) that is spaced apart from the arcuate photoconductive member (12). A plurality of arcuate opaque lines are disposed on the screen member (32) such that the plurality of arcuate opaque lines are centered along the longitudinal axis thereof. Each of the lines is dimensioned such that it represents the mirror image of the shadow on the photoconductive member that would exist if a straight line were disposed on the screen at the same position.

Abstract: A dual mode electrophotographic print engine. A voltage controller (25) provides operating voltage to a scorotron (27), which applies a charge to a photoreceptive medium. In a first mode a screen (40) is placed in a first position, out of the optical path between the image focusing device and the photoreceptive medium (45). This produces full exposure of the photoreceptive medium (45) to the focused image. This produces a latent image on the photoreceptive medium. Toner is then applied to the latent image to produce a developed image. In the second mode of operation, for producing half-tone copies, the screen (40) is inserted into the optical path. This reduces the exposure of the photoreceptive medium (45). To compensate for the reduced exposure the voltage controller (25) provides a second, lower voltage to the scorotron. This lower voltage compensates for the reduced exposure time so as to produce a high quality latent image. Toner is then applied to the latent image to produce a developed image.

Abstract: A method for measuring and adjusting the toner density of black toner in a multi-color copy machine includes first developing and transferring a layer of yellow toner (132) onto the surface of a transfer belt (18). A crosshatch pattern (134) of black toner is then developed and transferred onto the surface of the yellow toner layer (132) in a series of patches (138)-(148). The cross-hatch pattern (134) is comprised of vertical and horizontal bars (136) that are spaced a predetermined distance apart and have a predetermined width. A toner density sensor (40) is disposed over the surface of the transfer belt (18) to measure the toner density. The amount of toner deposited on a photoreceptor belt (12) is altered by varying the grid voltage on a charging corona (28) during the developing step to provide multiple toner densities for each of multiple patches (138)-(148). This data is then extrapolated to determine what the grid voltage on the charging corona (28) should be for the desired toner density.

Abstract: A belt conditioning system for a flexible belt electrophotographic print engine includes a cleaning blade (144) which is operable to clean a transfer belt (20) on a per page basis. A roller (152) is operable to be disposed in contact with the belt (20) on a page intermittent basis to more aggressively condition the belt (20). A controller (39) is operable to activate the roller (152) on a page intermittent basis and, during activation of the roller (152), transfer of images to the transfer belt (20) from a PC belt (30) is inhibited to prevent any registration problems from occurring during the conditioning cycle.

Abstract: A print engine including a photosensitive belt which is an endless loop vertically mounted in the copier or printer housing. A photosensitive belt stretches over a pair of rollers such that the exterior of the surface of the belt defines a developing position for an electrostatic image in a substantial vertical plane. An exposure station in the copier housing focuses light on the developing position of the photosensitive belt forming the electrostatic image. Toner applied to the electrostatic image forms a developed image which is transferred to a second endless loop belt and subsequently communicated and fixed on an image receptor, such as paper. A second endless loop belt stretches between a first roller and a second roller. The first roller is vertically spaced-apart from the second roller. Each roller is horizontally and vertically off-set from one of the pair of rollers around which the photosensitive belt is stretched.

Abstract: A toner module has a mixing roller and a decorator roller. The decorator roller, which extends partially through a developer opening, has a partial magnetic core enclosed by a developer carrying sleeve. Developer is removed by orientating a nonmagnetic portion of the core toward the developer opening. The decorator roller is then rotated so that the sleeve carries the used developer over the nonmagnetic portion, thereby allowing the developer to fall out of the toner module. New developer is added by orientating the magnetic portion of the core to face the developer opening. The decorator roller is then rotated so that, as the sleeve rotates over the developer to be added, the magnetic force of the developer core pulls the developer onto the sleeve and into the toner module. Orientating a magnetic portion of the mixing roller proximate to the decorator roller causes the developer to be carried further into the toner module, so as to provide for more storage volume for the developer.

Abstract: In an electrophotographic system, a compact, space-efficient device is provided which allows adjustment and quick release of a photosensitive belt. An idler roller supporting the belt is used in conjunction with a cam which provides a take-up feature. A configuration is provided which allows the cam to be disengaged, and the idler roller retracted to facilitate removal of the belt.

Abstract: A transfer mechanism for a full color double transfer electrophotographic print engine. Relatively conductive developer materials having successively increasing triboelectric charge characteristics are used to develop sequential images. Conductive plates displaced away from the transfer station along the direction of travel of the transfer belt are used as one electrode for applying an electrostatic field at each transfer station. A parameter of the transfer mechanism is a bulk resistivity of the transfer belt in the range of 10.sup.7 to 10.sup.10 ohm-centimeters and a surface resistivity for the belt in the range of 10.sup.7 to 10.sup.10 ohms per square. A selectively operable compression roller, compressing paper and transfer belt against a rubberized idling roller at one of the transfer stations increase dwell time in the transfer station. The compression roller automatically falls to a cleaning station where it is rotated by another rotary member to clean it between transfers.

Abstract: An electrophotographic print engine with a photosensitive flexible belt stretched over a plurality of rollers in a compact electrophotographic printer such that a developing position on the belt is disposed in a vertical plane, the developing position exposed first to a light on one side of the printer and activated to trace the image of the document to be printed and second passed vertically adjacent at least one toner module extending a decorator roller horizontally to the photosensitive belt on a second side of the printer to create a developed image, the developed image transferred at the upper end of the vertically disposed belt to the downward facing side of a sheet of paper which passes through a fuser to fix the print before the paper is placed facedown in an output tray, permitting the compact printer to create multi-page documents in sequence without manual re-sorting of the document, residual toner wiped from the vertically disposed belt to fall by gravity to a modular collection receptical.

Abstract: An improved fuser for use in an electrophotographic print engine having mutually compressible rollers for uniformity and thoroughly fused toner images. Also, the need for paper fingers to guide image receptor sheets is eliminated. The wear on the fixing device in the improved fuser is reduced by preventing binding of oil leveling blades, removing offset toner, and the use of oiling rollers in conjunction with oil leveling blades to apply oil to the fixing device. An improved fuser is also easily accessible and serviceable. The fusing device is contained within a clam-shell housing such that the fixing device and the compression device are separated when the housing opens thereby freeing jammed image receptor sheets and allowing convenient access for further service and repair. In addition, an oil wick, an oil tank, and the leveling blade comprise a subassembly which can be removed and replaced.

Abstract: Improved cleaning station for use in electrophotographic print engines which selectively removes toner from a transfer medium and has cleaning elements which are simple to remove, clean, and replace. The transfer medium cleaning station is equipped with a locking mechanism that allows inserting the cleaning station into and removing it from the print engine without scraping the transfer medium with the cleaning element.

Abstract: Improved cleaning stations for use in electrophotographic print engines having cleaning elements which are simple to inspect, remove, clean, and replace. The photoreceptor belt cleaning station is positioned in one frame of the print engine and the photoreceptor medium is positioned in the other frame of the print engine so that the cleaning station is directly accessible when the print engine is open. Also, when the print engine is closed, the photoreceptor medium contacts the cleaning elements at a substantially perpendicular angle resulting in minimum stress to both the photoreceptor medium and the cleaning elements.

Abstract: An improved toner module for use in an electrophotographic print engine. A decorator or developer roller with a rotatable core provides an apparatus for, and an improved method of, replacing developer. The decorator roller has a core that is partially magnetic and partially nonmagnetic. By rotating the decorator core to adjust the position of the non-magnetic portion of the decorator core, developer can be both removed and added without the use of any additional equipment. A mixing roller within the toner module provides for greater quantity of developer to be stored within the toner module. The disclosed toner module therefore has a greater capacity for storage of developer.

Abstract: A method and apparatus for controlling belt movement and separated image registration in a belt oriented full color double transfer electrophotographic print engine is disclosed. The photoreceptor and transfer belts have a ratio of lengths which is nominally equal to an integer. Independent servos control rotation of the belts driving each at a constant rotational period. The rotational periods are calculated so that their ratio is precisely equal to the above referenced integer value which is the nominal ratio of the belt lengths. A plurality of separated image creation and development control signals are provided under the control of an event timing clock. The event timing clock is preset to a predetermined modulo M value, M being the units of time for the targeted rotational period of the transfer belt, each time a reference pulse is provided from a reference station associated with the transfer belt indicating that a predetermined location on the transfer belt has arrived at the reference station.

Abstract: An improved color correction apparatus for improved color printing in a subtractive color printing system is disclosed. The disclosed apparatus utilizes an optimized three-dimensional look up table of pigment density values addressed by primary color values. The look up table is created by printing a plurality of pigment bars in response to known input density signals to a laser beam for each of three color pigments used in the system. Each of these sets of bars is subsequently scanned by the input scanner to determine the spectral content of the resultant bars and thus create a plurality of color pigment values corresponding to the spectral content of each bar for each color which is a complementary color of one of the pigments. These characteristics are used to calculate the spectral content of an actual printed image generated in response to an image generated by an input triplet to the system.

Abstract: An improved full color electrophotographic print engine using flexible belts to carry a photosensitive electrostatic image developer and a transfer belt for building up composite developed images. Each belt, and an optical scanner, are driven by mechanically independent motors which are synchronized by an electronic digital controller implementing precise servos. The use of the flexible belts allows the machine to be relatively inexpensive, very small compared to previous full color print engines, and yet maintain precise registration of color composite images. An improved fuser mechanism with increased dwell time at constant machine speed is also shown. The fuser includes a pair of spaced-apart rollers, both of which urge a sheet of image receptor against the heated roller over a predetermined angular portion of the roller. The machine is specifically designed to be used interchangeably with an optical bench source as a copier or with a laser bench as a laser printer.

Abstract: Improved dual belt synchronization for a print engine for color electrophotography using a photoreceptor belt and a seamless transfer belt on which a composite image is built up. Improved synchronization of the two belt drives enhances image registration. A tension mechanism used in conjunction with the belts prevents rapid changes in the belt dimensions. An improved transfer belt cleaner system is synchronized with the belt drives such that excess toner is not left in the imaging area of the transfer belt.

Abstract: A color filter interpositioning mechanism for use in an electrophotographic print mechanism which uses motor driven pulleys to move a belt which is located directly beneath a grooved track into which the color filter assemblies are inserted. The belt contains spaced apart holes which are brought beneath the color filter assemblies, by the rotation of the belt about the pulleys, thus allowing a spring loaded pin, attached to each filter, to fall through a slot in the grooved track and into the hole. The filter assembly is then drawn down the track and into an optical path. A sensor detects when the filter is properly positioned in the optical path and signals the motor to stop. An image of the original to be copied is then projected through the filter and onto a photoreceptor.

Abstract: An improved full color electrophotographic print engine using flexible belts to carry a photosensitive electrostatic image developer and a transfer belt for building up composite developed images. Each belt, and an optical scanner, are driven by mechanically independent motors which are synchronized by an electronic digital controller implementing precise servos. The use of the flexible belts allows the machine to be relatively inexpensive, very small compared to previous full color print engines, and yet maintain precise registration of color composite images. An improved fuser mechanism with increased dwell time at constant machine speed is also shown. The fuser includes a pair of spaced-apart rollers, both of which urge a sheet of image receptor against the heated roller over a predetermined angular portion of the roller. The machine is specifically designed to be used interchangeably with an optical bench source as a copier or with a laser bench as a laser printer.