Abstract: A media advancing device for a hardcopy apparatus comprising: a platen having at least one slot and a top surface, whereby a medium advances on the top surface; and a plurality of openings connecting the top surface to at least one zone of negative pressure; and a revolving overdrive roller having an outer surface, the outer surface emerging above the top surface through the slot, the overdrive roller being substantially sealed in a housing below the top surface, the housing separating the overdrive roller from the zone of negative pressure.

Abstract: A hold down apparatus for use in a hardcopy device (20) comprising a first surface adapted to support a sheet of print media (74) thereon and a vaccum guide arranged to support a partial vacuum, the first surface having a plurality of apertures therein in fluid communication with the vacuum guide via a porous or labyrinthine flow restraint (82a, 82b), the apparatus being arranged such that downstream of the apertures, unimpeded vacuum flow between the plurality of apertures is substantially prevented.

Abstract: A media advancing device for a hardcopy apparatus includes at least one roller having an outer surface and being rotatable for advancing media, and a negative pressure mechanism. The outer surface further comprises a plurality of openings and a contact region for engaging the media, wherein the negative pressure mechanism is capable of creating negative pressure through at least a portion of the openings in the contact region.

Abstract: A printing device includes a print media advancement subsystem for providing accurate and timely print media advancement in the printing device. The print media advancement subsystem includes a vacuum chamber for generating a vacuum force through a platen for holding a print media stationary. In response to receiving a print media advance signal from a controller in the printing device, a sealing plate forming a side of the vacuum chamber is removed from the vacuum chamber. When the sealing plate is removed, the vacuum chamber is substantially open to the atmosphere, causing the vacuum chamber to pressurize. The pressurization of the vacuum chamber results in removal of the vacuum force from the print media, allowing the print media to advance along the top surface of the platen with minimal friction.

Abstract: A vacuum holddown device for a hardcopy apparatus, comprising a printing platen with a pattern of through holes and an underlying vacuum chamber, further comprises a member located therebetween and having a substantially similar pattern of through holes, the member being moveable to align the pattern of holes or not so as to respectively interconnect or disconnect the holes in the printing platen and the vacuum chamber. The member may itself define a secondary chamber with which the holes in the printing platen are in communication when not in communication with the vacuum chamber.

Abstract: A media outputting device for a hardcopy apparatus includes a media source and at least one roller having an outer surface with a contact region for engaging media, where the roller is rotatable for outputting the media. The media outputting device also includes a negative pressure mechanism for creating a negative pressure distribution on the contact region where at least one portion of the contact region that is farther from the media source has a greater negative pressure than at least one portion of the contact region that is closer to the media source.

Abstract: A printing device includes a print media advancement subsystem for providing accurate and timely print media advancement in the printing device. The print media advancement subsystem includes a vacuum chamber for generating a vacuum force through a platen for holding a print media stationary. In response to receiving a print media advance signal from a controller in the printing device, a sealing plate forming a side of the vacuum chamber is removed from the vacuum chamber. When the sealing plate is removed, the vacuum chamber is substantially open to the atmosphere, causing the vacuum chamber to pressurize. The pressurization of the vacuum chamber results in removal of the vacuum force from the print media, allowing the print media to advance along the top surface of the platen with minimal friction.

Abstract: A media advancing device for a hardcopy apparatus includes at least one roller having an outer surface and being rotatable for advancing media, and a negative pressure mechanism. The outer surface further comprises a plurality of openings and a contact region for engaging the media, wherein the negative pressure mechanism is capable of creating negative pressure through at least a portion of the openings in the contact region.

Abstract: A vacuum holddown device for a hardcopy apparatus, comprising a printing platen with a pattern of through holes and an underlying vacuum chamber, further comprises a member located therebetween and having a substantially similar pattern of through holes, the member being moveable to align the pattern of holes or not so as to respectively interconnect or disconnect the holes in the printing platen and the vacuum chamber. The member may itself define a secondary chamber with which the holes in the printing platen are in communication when not in communication with the vacuum chamber.

Abstract: A media outputting device for a hardcopy apparatus includes a media source and at least one roller having an outer surface with a contact region for engaging media, where the roller is rotatable for outputting the media. The media outputting device also includes a negative pressure mechanism for creating a negative pressure distribution on the contact region where at least one portion of the contact region that is farther from the media source has a greater negative pressure than at least one portion of the contact region that is closer to the media source.

Abstract: A misalignment compensation technique for a dot printer is disclosed. This technique first supplies printing instructions to a printhead for energizing printing elements in various groups (primitives) to print a pattern on a medium. The printed pattern is then detected by optical sensors in the printer. Based on the detection, a position offset error for each primitive is determined. These errors are used to generate a separate time correction for each of the primitives such that, when the printer is used normally, the time period for printing a dot will be advanced or delayed for each primitive so as to align the dots printed by the primitives. In another embodiment, alignment data taken by a manufacturing line sensor is stored in a memory on the print cartridge. After the print cartridge is installed in the printer, a second optical test completes the data needed to create timing correction values.

Abstract: A hardcopy apparatus includes a media holddown unit, having a platen, and a vacuum source for generating negative pressure on a medium positioned on said platen to keep it flat on said platen. The unit includes at least two vacuum chambers, both in air communication with the vacuum source. Each of the vacuum chambers can apply a negative pressure to a different portion of the medium positioned on a corresponding different region of the platen. A method for holding down a medium when placed on said platen. First the vacuum source is placed into independent air communication with a number of distinct regions of the platen, then the medium is positioned to cover one or more regions of the platen, and finally a negative pressure is applied to the back of the medium via the independent air communication.

Abstract: Techniques to compensate for random and systematic errors when measuring dot placement errors. Error accumulation due to scan axis irregularities during printhead calibration is minimized by swapping alignment block positions on the print medium from swath to swath. Print media advances during the calibration are minimized by the use of a moving reference instead of a constant reference; adjacent groups of nozzles are used to calibrate the following group. Only a small media advance is needed to print alignment blocks using adjacent nozzle groups one beside the other to be calibrated. To prevent paper slip accumulative errors when using moving references, the order of the groups of nozzles is swapped from one paper advance to the other. This randomizes for small, unavoidable slips when advancing the paper and prevents error accumulation.

Abstract: A carriage-mounted optical sensor for an ink-jet hard copy apparatus includes a unitary light tube member which holds the optical components in fixed positions relative to each other as well as relative to an outer protective casing which attaches to the carriage. The light tube member serves as a cap to capture two LEDs between itself and a protective casing, to capture an optical lens between itself and a photocell holder, and to directly engage the casing. An inner wall having light redirecting features provides an improved light path cylinder and the device obtains a more accurate representation of the test pattern mark shape, reflectance value, and position.

Abstract: In various methods, image registration variations among test patterns are used to calibrate misalignment among one or more printheads, paper advance distance, different portions of an inkjet printhead, or bidirectional printhead alignment. A set of test patterns are printed. Each pattern includes a reference portion and a varying portion. The varying portion is changed from pattern to pattern in a manner for testing a parameter being calibrated. An optical sensor scans each test pattern. The parameter setting for the lest pattern having the highest reflectance (i.e., most blank space) is selected as the calibrated parameter value.