Abstract: A bracket to mount a charge roller and a blade against a photoconductive drum within an image forming apparatus. Bracket may include a pair of guides that extend outward to receive the ends of the charge roller. A biasing device may be positioned to bias the charge roller against the photoconductive drum. The guides may include an opening sized to allow the charge roller to move and maintain contact with the photoconductive drum. A mounting surface may be positioned on the bracket for receiving adhesive to mount the blade. In one embodiment, the bracket is constructed of an electrically conductive material such that a charge introduced to the bracket is delivered to the charge roller.

Abstract: Toner usage is measured with good accuracy. Printing tends to darken with the depletion of toner from a source. A toner cartridge employed in a printer (70) has the capability at the cartridge of determining the amount toner used. In an embodiment this is by a torsion spring (60) drive to a toner paddle (3). At turn-on and cover open, the amount of toner is measured at the cartridge (80). That is stored in NVRAM (78) when it is very different from the current amount stored in NVRAM. At certain amount levels observed at the cartridge the amount in NVRAM is revised to the new amount. Between those levels the amount of toner used is tracked by counting pels (94). Use amounts are converted to operating factors in a table (100), and the operating factors are applied to the printer to keep the darkness of printing more constant. Writing to NVRAM is minimized.

Abstract: An improved method of digital halftoning using “screens” or dither arrays is provided, including stochastic dither arrays (e.g., stochastic screening). The weakness of ordinary stochastic dithering is its isolated or dispersed dots and the related problems of dot gain and consistent dot formation when used with certain types of printers. However, the inconsistent formation of isolated dots causes unpredictable variations in uniformity and tone. The present invention solves this problem by grouping dots into small clusters, which may be rendered more consistently. Unlike conventional clustered-dot halftoning, however, this method arranges the dot clusters in a stochastic fashion to avoid objectionable periodic artifacts. A novel weighting function is used to generate the dot clusters, in which one function of a first extent is subtracted from another function of a second extent, thereby creating clusters of dots that center at locations where the weighting function chooses to place dots.

Abstract: A layered intermediate used in inkjet printing contains a release coat formed on a transfer medium in an area where an image has not been printed. The release coat is formed of polyvinyl pyrrolidone (PVP) or a PVP copolymer and at least one solvent selected from the group consisting of glycol solvents and diol solvents. A viscous coating of PVP or the PVP copolymer is formed on the transfer medium in an area where an image has been printed. A release layer formed from components in the release coat and components in the ink is formed on the viscous coating. A first ink layer is formed on the release layer of flocculated ink. A second ink layer is formed on the first ink layer, of ink that is substantially not flocculated.

Abstract: Toner hopper (1) of a printer (70) has a stirring paddle (3) with an encoder wheel (30, 50) mounted on paddle shaft (5). The drive connection to paddle (3) is through a torsion spring (60). Data processing apparatus determines paddle acceleration or deceleration (90, 94, 98, 102) and executes a table look-up to determine scaled amounts of subsequent movement (92, 96, 100, 104). Steady state movement is a unitary (unscaled) amount (106). These amounts are totaled (93) and used to define yield at the torsion spring, which corresponds to amount of toner in the hopper. This eliminates hardware in previous embodiments at the drive motor to signal actual rotation of the drive motor.

Abstract: A device and method of supporting a doctor blade within an image forming apparatus. The device has a housing for positioning a doctor blade such that a bottom edge contacts a developer roller. One or more extensions are positioned to support a first side of the doctor blade. The one or more extensions may include dampeners which are constructed of a resilient material. Supports are positioned on a second side of the doctor blade. The doctor blade is sized to fit between the one or more extensions and the supports. A method of supporting the doctor blade includes positioning the doctor blade to dampen vibrations and velocity fluctuations caused by sticking and slipping of the bottom edge of the doctor blade against the developer roller.

Abstract: A fuser latch system suitable for a customer replaceable fuser unit. Front holders include datum receivers on a base machine frame and datums on the fuser frame. Rear latches include retainers connected to the base machine frame, and axially translatable and rotatable shafts connected to the fuser frame. An end of the shaft is received in a retainer upon axial translation of the shaft, and locked in place upon rotation of the shaft. The rear latches bias the fuser frame for proper gear mesh and paper path alignment.

Abstract: A laser beam sensor assembly in an electrophotographic machine includes a sensor device detecting a position of a laser beam in a process direction. The sensor device has a detection range in the process direction. The sensor device has at least one slot or at least one projection. A fixed structure has an other of the at least one slot and the at least one projection. The at least one slot and the at least one projection coact to allow the sensor device to slide in the process direction to a location such that the laser beam is at a desired position within the detection range of the sensor device.

Abstract: Heat rolls and fuser belts utilized in the fusing step of the electrophotographic process are disclosed. These belts and rollers eliminate toner offset while still maintaining excellent release characteristics of the printed page from the fuser. The heat rolls comprise a core member having coated thereon a plurality of concentric layers, wherein at least one of said layers (preferably the top layer) does not contain electrically conductive materials and wherein the roll exhibits electrical breakdown at about 250 volts or less. The fuser belts comprise a heat resistant resin substrate (such as a polyimide belt) carrying thereon a plurality of layers coating the outer surface of said belt, wherein at least one of said layers (preferably the top layer) does not contain electrically conductive materials and wherein the belt exhibits electrical breakdown at about 250 volts or less.

Abstract: A method of determining misalignment of color planes within an image forming apparatus. A first pattern is formed with a first color and comprises first and second sections. A second pattern is formed with a second color and positioned within the first and second sections of the first pattern. The alignment of the two color planes is determined by the difference in the amount of color within the first and second sections. The amount of misalignment may further be determined by the ratio of the difference in the amount of color within the sections and the sum of the amount of color within the sections. Perfect alignment of the two color planes results in equal color amounts in each section.

Abstract: A single-pass color electrophotographic printer includes four imaging stations, yellow, cyan, magenta, and black, on a generally linear path. A toned image in each toner color is developed on an image bearing member or photoconductive drum. A plurality of electrically biased first transfer rollers associated with each imaging station is operative to transfer the developed images from the photoconductive drum to an intermediate transfer member (ITM) belt that travels sequentially past the imaging stations along the generally linear path in a first transfer operation. The image on the ITM belt is transferred to media at a second transfer operation at which the ITM belt passes through a nip between a backup roller and a further electrically biased transfer roller. A servo operation is used to set the voltages on the transfer rollers. Rollers at the second transfer are positioned to direct media downwardly out of the nip to a media transport belt and to a fuser assembly.

Abstract: A two part cartridge having a photoconductor part (1) and a toner part (5) having no force biasing element on either part. The two parts fit together so that a developer roller (7) in the toner part contacts a photoconductor drum (3) in the other part. When the two parts are installed in a printer the cover (50), when closed, brings a spring (62) into contact with one side of the toner part while the frame (F) of the printer blocks movement away from the cover. An advantage of the two part cartridge is that the toner part can be replaced without replacing the photoconductor part. Members on the cartridge for force biasing are avoided and the need for training or skill to latch the parts together is avoided.

Abstract: A pre-scan optics assembly for a laser scanning device. A housing includes reference surfaces against which a pre-scan lens is directly referenced, to restrain the lens against rotation about the optical axis and the scan axis of the device. A lens carrier is attached to the housing and has an abutment surface to restrain the lens against rotation about the process axis of the device. A spring clip secures position of all components in the desired locations. The optical system aperture is formed directly in a wall of the lens carrier.

Abstract: Transfer belt subassembly for a color printer includes a transfer belt, home position indicator, temperature sensor, and memory. The transfer belt subassembly is measured and characterized after fabrication, before being installed in a printer. Measurement and calibration data for the transfer belt is stored in memory as part of the subassembly, including data representing velocity characteristics of the transfer belt and temperature compensation factors used by an engine-controller in a method to govern the speed of the drive motor. When the transfer belt subassembly is inserted into a printer, the engine-controller is operative in response to data stored in the memory and sensed belt velocity and temperature data, providing adjustment of belt velocity and compensation for variations in the transfer belt speed. Using the predetermined characterizing data, precise alignment of the color planes with respect to one another is achieved for accurate color printing.

Abstract: A multiple output spread spectrum clock circuit is provided that reduces electromagnetic emissions when two different clocks operate at frequencies which overlap one another. Two such clock circuits are controlled so as to introduce a phase difference between the clocks as they operate through their spread spectrum profiles. The “best” phase differences are around 18%, or around 50%, between adjacent spread spectrum clock outputs. The phase difference can be controlled by starting the first clock (SSCG #1) at one point in time, while temporarily delaying the start of the second clock (SSCG #2) until the appropriate moment; alternatively, it can be controlled by starting both clocks at the same moment in time, however, SSCG #1 begins at one point in the spread spectrum profile, while SSCG #2 begins at a different point in its spread spectrum profile.

Abstract: The present invention relates to graft copolymers, useful as dispersants in ink jet ink compositions, which comprise two structurally distinct segments: a hydrophilic segment and a hydrophobic segment. The preferred hydrophilic segment is comprised preferably of a methacrylic acid polymer, or a copolymer thereof with another monomer, such as styrene sulfonic acid. The preferred hydrophobic segment comprises a polymer or copolymer containing electron rich functional groups comprised of a plurality of methacrylate derivatized monomers, preferably a methacrylate ester monomer, or a substituted methacrylate ester monomer (a methacrylate ester where the alkyl group is replaced with a siloxyl substituent, an oligomeric siloxane). The present invention also relates to aqueous ink compositions which include the polymeric dispersants of the present invention. A further embodiment of the present invention comprises a polymer comprising a monomeric hydrophobic head and a polymeric tail.

Abstract: The write lines of a color laser printer are maintained substantially equal throughout the printer's operation by an electronic control arrangement. At the factory, the write lines on all photoconductors of the color laser printer are calibrated to be substantially equal, and the ratio of each write line to a measuring line for each photoconductor is ascertained. During operation of the printer, the length of each of the measuring lines is periodically determined through counting the number of PELslice clock timing pulses produced from a PELslice clock operating at a fixed frequency determined during factory calibration. The length of the write line is determined by the product of the length of the measuring line and the factory calibrated ratio of the length of the write line to the length of the measuring line.

Abstract: A printer is provided which has a special Emulation Manager function as well as a “code sniffer” function, in which print data received is sent to a code sniffer buffer. A code sniffer function automatically determines the type of emulator that should be called to perform the interpretation or rendering of this print job, and if the code sniffer determines that the correct emulator is PostScript, then the code sniffer scans the data for any “special tokens.” If a special token is found, the PostScript emulator determines if the special token string data is part of a PostScript comment. If it is in the correct format, then the PostScript emulator sets the “mode flag” to the “MacBinary” state, and the code sniffer ceases any further filtering of control characters and disables any change of emulator command that may be received during this print job.

Abstract: The present invention relates to ink compositions. More particularly, the present invention relates to ink compositions comprising a colorant and a polymeric binder having a below ambient glass transition temperature, an average particle diameter above about 200 nm and an acid component ranging from about 1% to about 10% by weight of the polymeric binder. Additionally, the present invention has the novel and useful feature of resistance to both wet-rub and dry smear as well as increased highlighter resistance and decreased occurrences of maintenance problems such as clogging and kogation.

Abstract: The invention provides a method for making piezoelectric printheads for ink jet The method includes applying an insulating layer to a first surface of a silicon wafer having a thickness ranging from about 200 to about 800 microns. A first conducting layer is applied to the insulating layer on the first surface and a piezoelectric layer is applied to the first conducting layer. The piezoelectric layer is patterned to provide piezoelectric elements on the first surface of the silicon wafer. A second conducting layer is applied to the piezoelectric layer and is patterned to provide conductors for applying an electric field across each of the piezoelectric elements. A photoresist layer is applied to a second surface of the silicon wafer, and the photoresist layer is imaged and developed to provide pressurizing chamber locations. The silicon wafer is then dry etched through the thickness of the wafer up to the insulating layer on the first surface of the wafer.