Hewlett-Packard Development Company, L.p.

Hewlett-Packard Company

Hewlett-Packard Development, L.p.

Miquel Boleda

Ferran Vilanova

Eng-Long Goh

David J Arcaro

James L McCullough

Michael Nelson

Steven W Trovinger

Eric Lee Burch

Howard G Wong

Francesc Subirada

David Michael Kwasny

Michel Georges Encrenaz

Esteve Comas

Paul David Gast

David Herbert Donovan

Robert R Giles

Marc Serra

Gary E Hanson

Xavier Gros

Abdolreza Movaghar

Johan Maurice Lammens

Jose Julio Doval

Jorge Castano

Dennis Sonnenburg

Albert Serra

Stephen Ledak

Salvador Sanchez

John Havard

Francisco-Javier Pozuelo

Greg Burke

Guillaume Montaclair

Keith William Kirkwood

Lionelle Grandmougin

Jes&uacute;s De La Lama

Michel Encrenaz

Jose Gabriel Escabia

An inkjet printing apparatus comprises at least one printhead which comprises at least one ink chamber and a plurality of nozzles, at least one ink container remote from the printhead, an ink delivery system comprising a source of gas under pressure operable to supply ink from said remote ink container to said ink chamber on the printhead, a priming device arranged to prime at least one printhead and comprising a connecting assembly to connect the source of gas under pressure to the printhead to be primed, and a controller to control the flow of gas through said connecting assembly to provide upon demand gas under pressure to the printhead in order to cause a flow of ink from the ink chamber through the nozzles to prime the printhead.

Inkjet printing apparatus with a priming device

A method of finishing a plurality of sheets for a bound document. The method comprises accumulating a stack of sheets at a first position, scoring the sheets at the first position, and outputting the stack of scored sheets from the first position.

Method and apparatus for finishing sheets for a bound document

Example embodiments of a media handling system are shown and described in which gears are moved by a carrier into engagement with a gear that is operably coupled to a media driver.

Media handling system

Example embodiments of a media handling accessory and method are illustrated and described, wherein the accessory includes a media input tray and a duplexing path.

Media handling accessory and method

CDE is measured for each nozzle array, to enable modification of a mapping between input image data and intended printing marks to compensate for the CDE. Printing proceeds using the modified mapping, which is either an optical-density transformation of data to printing marks or a spatial-resolution relation between image data and intended pixel grid. The density transformation preferably includes a dither mask (but can be error-diffusion thresholding instead); the resolution relation includes scaling of image data to pixel grid. For some invention forms, CDE includes printing-density defects, measured and used to derive a correction pattern&#x2014;in turn used to modify halftone thresholding. For other forms CDE includes swath-height error, but still this is measured and used to derive a correction pattern etc. For still other forms, however, CDE includes swath-height error and correction takes the form of scaling. When the halftoning forms are applied to plural-pass printing, a printmask is used to map the dither mask etc. to the nozzle array, enabling application of the correction to the mask. Halftone forms ideally uses a gamma function, though threshold or linear corrections are possible instead. Halftone correction is effective in single-pass printing. The swath-height correction can modify heights of all nozzle arrays. Computations are done at most only once for a full image.

Apparatus and method for mitigating colorant-deposition errors in incremental printing

PPS variation along a scan axis is found by shining a light beam from pen carriage to print-medium position and back to detector, and applying a pathlength/intensity correlation. Sensing is done while scanning, to find relative PPS profile along the track. With no medium in place this measures mechanical imperfections&#x2014;and can be corrected by later deducting thickness of a medium. If medium is present, adjustment is omitted. For absolute values a plural-lamp sensor is calibrated for each lamp, at the PPS design point. Pagewide/webwide variants are included.

Printhead-to-platen spacing variation along scan axis due to carriage guide, measured by simple sensor on carriage

Absolute perceptual values are stored in the design lab, for maximum-density-tone cutoffs&#x2014;preferably a maximum yellow-blue chrominance b* for yellow and minimum luminosity L* for other colorants. Automatic field operations in each printer then force the printer to subsequently print nominal full-saturation colorants so as to match the stored values. In addition to the stored cut-offs, black-and-white reference values measured in the printer are also used in linearizing printer response, for specific combinations of printing medium and printmode.

Closed-loop color correction using factory-measured color cutoffs anchored to field-measured white point

A thermal transfer overcoating technology for reducing overcoat tags. Skewing the interface between a carrier ribbon to coated document at the peeling of the carrier from the coated document concentrates the forces at the interface to a smaller region of the document edge. Moreover, tensioning the document at the interface changes the forces at the interface from peeling type to tensile type.

Thermal transfer overcoat tag reduction

Method and apparatus for thermal transfer overcoat technology. Throughput conditions are anticipated. Multi-stage preheating of the fuser is performed such that active heating during thermal transfer overcoat is eliminated. Thermal waves create an accumulated fuser heat that is a sufficient energy to maintain a substantially constant fuser temperature needed for one whole thermal transfer overcoat cycle.

Anticipative temperature control for thermal transfer overcoating

Computation and data-storage are minimized in both accounting for element condition and reallocation of print tasks away from subnominal elements. An accounting function maintains an element-condition tabulation partly in a cumulative form&mdash;representing element stability directly without later interpretation. A reallocation distributes print burden from a subnominal element to plural other elements without making a new mask. Rather, entries for a poor element in a current mask are shifted prospectively and quickly to other elements serving the same pixel rows.

Streamlined real-time printmask revision, and printing-element data system, to circumvent element malfunction

Combined media handling and material applicator printer

Techniques for printing ink drops in an inkjet printer, where at least one color ink can be printed by two (or more) printheads. The drops to be printed are divided between the two printheads with purposes of higher printer velocity, higher image quality and higher print reliability.

Multiple marker inkjet printing for increased print speed

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. No further paper advances are used at all for the rest of the dot placement calibration (odd to even columns in a print-head, pen to pen correction and bidirectional correction). When calibrating X-axis position for a group of nozzles, a group of nozzles located at the same Y-axis coordinate is used, so that no paper advances are needed to print them one beside the other.

Techniques for robust dot placement error measurement and correction

A memory holds calibration data that are applied to compensate imperfections in a printhead-carriage guide rod, improving alignment between marks printed with different heads. Commonly heads and a carriage encoder are spaced from the rod at different distances, which interact with rod deviation to form dot-placement errors (DPE) that vary along the rod. The memory holds a single offset value, best a weighted composite of (a) an average of maximum and minimum deviations from straightness, and (b) median deviation, along the rod; or as the carriage moves on the rod the system steps or interpolates between successive offsets, or uses a continuous corrective-offset function. Separate offsets may be stored for adjacent-head pairs. The memory is best a digital unit holding just a few data bits, but may be a mechanical cam or linkage, compensation network or other analog circuit, polynomial coefficients, or codestrip with unequally spaced graduations. A custom strip is used with no further intervention. Calibration data in other memory types are used to modify interhead alignment, carriage-encoder signals, carriage position/speed, printhead-actuation timing or marking rapidity&mdash;or image-data position values, color-plane alignment, or pixel structure. Calibration may be prepared by measuring rod-straightness deviations, calculating expectable DPEs between mark pairs made by different heads, and from these finding the needed numbers for storage. Measuring may use conventional instruments but preferably the printer prints patterns (e.g. alternating marks made by two outboard heads) and measures them with an internal sensor. In existing systems&mdash;with interhead alignment set in a limited rod segment&mdash;the offset is found by comparing DPE ranges over the whole length vs. that segment.

Controlling residual fine errors of dot placement in an incremental printer

An inkjet printing device comprises a platen on which a printing zone is defined, a carriage, onto which at least a printhead is mounted, slidable along the printing zone near the platen, a service station, located in a service zone separated from the printing zone, a housing protecting and enclosing the printing zone and the servicing zone, and a device, for example a fan, for producing an air flow within the housing. A substantially constant air path is defined within the housing of the device through which the air flow is allowed to pass during its operation. A method for reducing ink aerosol in such a device, during its operation, comprises the following steps: producing an air flow within the housing, and forcing the air flow to pass through a substantially constant air path defined within the housing.

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Barcelona, Spain

Miquel Boleda