Hewlett-Packard Company

Hewlett-Packard Development Company, L.p.

Josep Maria Serra

Joan Manel Garcia

Mark S Hickman

Antoni S Murcia

Juan Carles Vives

Nathan M Moroney

Matt Bonner

Gonzalo Gaston

Michael J Klausbruckner

Kurt E Thiessen

Mark A Hay

Joan Manuel Garcia

Shailendra Kumar

Javier Lagares

Lluis Vinals

William J Allen

Ramon Borrell

A program creates a unitary mask for use over a whole image, with one pattern. The mask need not be full image size; it may be tiled. In the field a printer forms a mask and prints with it, best in the same session, before another image needing another mask, whether due to different image activity or type, or operating conditions. Constraints are controlled to ensure solution. Printout can start before a mask (even the part needed to finish a top swath) is done, going columnwise in each swath. In other invention facets, a program forms a mask of size significant relative to the program and prints with it. Other facets check print conditions and form adapted masks; or find nozzles that cannot back up a known-failed nozzle and to back it up form masks with all able nozzles; or assess image activity and inject mask randomness accordingly.

Masks on demand for use in incremental printing

In accordance with one embodiment, a system comprises a print head assembly comprising a plurality of ink-ejecting nozzles and a drying station downstream of the print head assembly and configured to produce and emit air proximate a print media. A deflector is mounted between the print head assembly and the drying station and is configured to deflect an amount of the air that is produced by the drying station.

Ink jet printing systems and related methods

A program with complete conditions for a usable mask yields a unitary mask, each try. One mask pattern is used throughout an image, but may be 'tiled'. Preferably the program, for given mask position, expresses favorability of several candidate pass numbers as a 'neighborhood constraint' in the form of a weight; distills the weights into one weight for each pass number; based on that, chooses a number for the position; and iterates for all positions. Many preferences are very useful, e. g. automatically balancing randomness vs. determinism, and several generalized relative notations. Another invention facet uses an input text file of mask constraints; a program reads constraints from the file, applies them, forms a mask and stores/uses it. Another reprocesses a mask for best image quality, fixing its own imperfections of first-round mask forming.

Fast building of masks for use in incremental printing

A shingle mask has width mismatched to maximum-eye-sensitivity spatial frequency at reading distance or closer, so the mask is tiled with minimal patterning. A second invention facet forms a grid of optimum width&mdash;it corresponds to maximum sensitivity only if seen from much farther than reading distance. A third facet forms a 2D mask with width 0.25 to 2 inches, better 0.375 to 1.5, ideally 0.5 to 1 (progressively further from maximum sensitivity; as further increases help little, this enables bandfree printing without very large masks). A fourth facet optimizes width in terms of distance in the image, for aesthetics, speed and economy. Another facet automatically forms a mask that time-varies nozzle-use modulation. Another prints nontext images by a multinozzle pen, modulating use; still others by plural pens each with a multinozzle array, refraining from use of certain nozzles e.g. to simulate dynamic pen staggering.

Optimal-size and nozzle-modulated printmasks for use in incremental printing

A method, printer system and printer apparatus for simultaneously printing a first print medium and a second print medium, wherein, on the first print medium first information is printed that is one of: identical information to the second information and information that includes at least some information different from the second information that is printed on the second print medium.

Simultaneously printing information on two sides of print media

In accordance with an embodiment of the invention, a method of aligning plural staggered pens in a printer with a first pen and a second pen of the plural pens defining a macro-pen, the first and second pens being staggered, the method includes aligning the first and second pens of the macro-pen and aligning a third pen with the macro-pen.

Method and apparatus for aligning staggered pens using macro-pens

Multiple-pass printing is performed with no print medium advance between selected pairs of printing passes. In some embodiments, an entire printing operation ( ) can be conducted in one multiple-pass mode. Alternatively, a switch from n-pass to m-pass mode may occur during a printing operation ( ) but with a uniform print medium advance throughout. Different printing masks are used for the different stages.

Printing with multiple passes

A program with complete conditions for a usable mask yields a unitary mask, each try. One mask pattern is used throughout an image, but may be &ldquo;tiled&rdquo;. Preferably the program, for given mask position, expresses favorability of several candidate pass numbers as a &ldquo;neighborhood constraint&rdquo; in the form of a weight; distills the weights into one weight for each pass number; based on that, chooses a number for the position; and iterates for all positions. Many preferences are very useful, e.g. automatically balancing randomness vs. determinism, and several generalized relative notations. Another invention facet uses an input text file of mask constraints; a program reads constraints from the file, applies them, forms a mask and stores/uses it. Another reprocesses a mask for best image quality, fixing its own imperfections of first-round mask forming.

In accordance with an embodiment of the invention, a method of aligning multiple staggered pens in a printer includes printing a series of test block patterns, the test block patterns containing a plurality of composite references printed with a set of pens from at least two rows of a pen arrangement of the printer and a plurality of alignment blocks. The method further includes measuring relative distances between the plurality of composite references and the plurality of alignment blocks to determine a per-pen misalignment and modifying pen operation to compensate for the per pen misalignment.

Method and apparatus for aligning staggered pens using a composite reference

An inkjet printing system uses high-resolution printheads holding different color inks to produce true 600 dpi color printing with a single pass of the printheads. By achieving a smaller drop size in the range of 25-50 picoliters for each printhead having a separate ink color (yellow, cyan, magenta, black), a full range of high-resolution color print-quality modes is possible. In an exemplary embodiment with a carriage scan speed of 25 ips, a two-pass draft mode uses a 7.5 kHz firing frequency, a four-pass normal mode uses a 4 kHz firing frequency, and an eight-pass best mode uses a 2 kHz firing frequency. In all of these print modes, each printhead can provide color inkdrop placement on every pixel row during a single pass.

High-resolution inkjet printing using color drop placement on every pixel row during a single pass

Bidirectional scanning printheads discharge color-ink drops at ultrahigh resolution while scanning in each direction, to form color swaths on a print medium. The heads are at least partially aligned with respect to the longitudinal axis of the medium, so that the swaths at least partly overlap in that direction. An advance mechanism intermittently steps the print medium longitudinally, to enable displacement of successive swaths. A control system alternates (1) one full reciprocation of the heads, to discharge drops while scanning each way across the medium, with (2) each step of the advance mechanism. Preferably the heads print, while scanning each way, a respective generally fixed nonzero fraction of the total amount of each secondary color to be printed. In this way the overall appearance of each secondary is essentially consistent and partway between two appearances respectively produced by scanning two ways. This invention avoids the long-printzone drawbacks associated with full-height-staggered heads. Preferably the fractions for all the swaths are about equal, so that the consistent appearance for each secondary is essentially the average of two appearances respectively produced by scanning two ways. Various printmasks complete each swath in eight passes with four print-medium advances, or four passes and two advances, or two and one&mdash;in each case printing in every pass.

Bidirectional color printmodes with semistaggered swaths to minimize hue shift and other artifacts

The method enables swath-type bidirectional printing without hue shift, using plural scanning multiple-inkjet printheads (holding inks of different colors respectively) and printing-medium advance orthogonal to the scan axis. Inking is calculated and implemented for each position in the grid independently. Images appear as a pixel grid of columns and rows both spaced--i.e. in both the scan and media-advance directions--more finely than 300 dpi. In one aspect of the invention, both these resolutions are the same, and equal to the nozzle spacing. At least some of the nozzles are overlapping and respectively aligned along the advance axis, to be capable of printing on adjacent rows during a single pass. In another aspect of the invention, the nozzle arrays only partially overlap, so as to use significantly fewer than the total number of nozzles in each array. As to this second aspect of the invention, in each nozzle array the method uses a number of nozzles that is fewer than the total nozzle complement by a certain number that is preferably at least fifteen, more preferably thirty, and ideally roughly sixty nozzles.

Bidirectional color printing using multipass printmodes with at least

Scanning printheads form a color image as inkdrops in a pixel grid on a print medium. Pixel row spacing equals nozzle pitch. Apparatus holds and provides (or creates in real time) a printmask using location rules that prevent addressing, within each scan, immediately neighboring pixels in any horizontal, vertical or diagonal direction. The mask is applied to control the heads. In other aspects of the invention, the rules also prevent addressing, in each scan, horizontally neighboring pixels within the entire width of the mask; or vertically neighboring pixels within its entire height; or immediate neighbors in any direction across a boundary--horizontal, vertical, or either--between abutting masks. Specific masks are set forth implementing these aspects. Another form of the invention yields a two-pass mask with this pass-number pattern: ##EQU1## Another form is a mask-creating-and-using method: generate a number series to define rows/columns of a pixel grid for printing in successive head passes, test the numbers against rules to minimize ink coalescence, and accumulate the numbers as an array to define a pixel grid--all automatically. Also check performance of arrays so generated, select a preferred one, and store it in a tangible medium for later automatic recall to control a printer.

Multipass color printmasks based on location rules to minimize hue

Color inkdrops form on a print medium in at least partly overlapping swaths. Apparatus holds and provides--or generates in real time--data defining a generally randomized printmask, which is applied to control working parts of an inkjet printer. Preferably the apparatus establishes an elemental pixel subgrid of rows and columns, used in determining inking patterns essentially throughout the image; and stores in the pixel subgrid a previously generated, generally randomized selection of pixel columns for printing of an inkdrop, in each subgrid pixel row--and conversely an analogous selection of pixel rows for printing a drop in each subgrid pixel column. Also preferably the generally randomized selection is subjected to location rules as to pixels above and to at least one side of each pixel. Numerous specific masks are specified as pass-number patterns, including an eight-by-eight 'knight' array, two sixteen-by-five arrays, a sixteen-by-ten array, and several four-by-four arrays. Another form of the invention includes apparatus for minimizing directional and other patterns in a printed color image, and coalescence and puddling of ink. A method of creating and using a printmask includes generating, as a row-and-column array, a series of essentially randomized numbers for use in defining rows or columns, or both, of a pixel subgrid; and storing the array in a tangible medium.

Growing community of inventors

San Diego, CA, United States of America

Josep Maria Serra