Hewlett-packard Company

Other

Lance B Cleveland

Gerold G Firl

Corrina A Hall

Timothy Zantow, Deceased

William James Allen

Ronald Albert Askeland

Mark S Hickman

Keshava A Prasad

W Wistar Rhoads

Abdolreza Movaghar

William C Hilliard

Catherine B Hunt

Two printing-medium guide systems restrain the medium. One is in an area upstream (along the direction of medium advance) from the pen, and extending laterally across the width of the medium except in one or more regions that are laterally near the engagement of a print-medium advancing device. The other guide system is disposed laterally from the pen, and extends laterally across the medium only in one or more regions that are laterally near the engagement of the advancing device. Preferably a human-actuable control selects a print-medium width, and shifts at least one bifurcation of the second guide system. A tensioning system, longitudinally beyond the marking head from the medium advancing device, and generally aligned laterally with that device, tensions the medium away from the advancing device to hold the medium taut at the pen. Preferably the advancing and tensioning devices are very closely spaced upstream and downstream, respectively, from the pen operating zone. When tensioned, the medium moves a normal distance through the apparatus at each operation of the advancing device; but after a trailing edge of the medium passes the advancing device (so that the medium is advanced only by the tensioner and is no longer tensioned), the advance distance is decreased (preferably by about half).

End-of-page advance-distance decrease, in liquid-ink printers

A battery terminal connector for a quick and easy way to connect and disconnect battery cables to a battery. The battery terminal connector includes a housing having an open top end, an open bottom end, an open side, a first side wall, and a second side wall and being adapted to retain a conventional battery coupler therein, and further includes a spring member having ends mounted to the first and second side walls at the open side, and also includes a lever pivotally mounted to the first and second side walls also at the open side and having a spring engaging member extending at an angle from an end of the lever, and further includes a cable fastener securely mounted on top of the housing.

Battery terminal connector

Images are printed by marks formed in pixel arrays by a scanning print head. During each scan marks are made in a pattern that approximates at least portions of many parallel, separated lines--angled steeply (best at about 3:1 slope, or at least much greater than 1:1) to the scanning axis and shallowly to the print-medium advance. Areas are left unprinted between the angled lines during one or more earlier scans for each image segment, and filled in during one or more later scans. Preferably the marks are made with liquid ink, and the medium heated to hasten drying. Heating causes an end-of-page paper-shrink defect that accentuates positional error components parallel to the print-medium advance; but the lines at a shallow angle to that advance tend to minimize those components--so the heating and steeply angled lines together promote high throughput while hiding the end-of-page defects. In practice the mark-forming includes placing marks only at pixels where marks are desired for a given image: the angled lines are incomplete where marks are not desired. The angled lines are at a steepest angle possible within design architecture of the scanning print head and print-medium-advance mechanism--or the steepest such angle consistent with a roughly equal number of marks per pen scan (for desired images in which all pixels are to be marked) and avoidance of other types of defects.

Maximum-diagonal print mask and multipass printing modes, for high

Images are printed using marks formed in pixel arrays by a scanning print head. For transparent and glossy media, with poor absorbance, drying is enhanced by a multipass (preferably six-pass) print mode in which the total number of ink drops or spots is allocated among correspondingly multiple masks, though some may be duplicates. To further hasten drying, heat is applied--through the medium, from the opposite side as that on which ink is deposited--but the amount of heat is strictly moderated, particularly for nontransparent glossy media, to accommodate the hypersensitivity of these media to heat-induced warping. Heating for glossy media is preferably restricted to about one-third the power used for drying plain paper. Convective drying too is promoted, by operating a fan over the printed image. Certain special techniques well-suited for plain-paper printing have been found undesirable for use with plastic media; these techniques include so-called 'resolution-enhanced technology', bidirectional printing (particularly of black), and optical-density controlled printing speed. At top and bottom of each page or sheet of printing medium, where it is undesirable to operate with the pen partly off the edge of the sheet, and where also the printing medium is constrained from only one direction rather than being held taut beneath the pen, the print mask is rotated while the printing medium is held stationary--thereby entirely avoiding reliance upon accuracy of print-medium advance.

Inkjet printing: mask-rotation-only at page extremes; multipass modes

At least one certain primary or secondary color is established that receives special treatment for at least one printing medium. Such treatment may include (1) using more than two drops of primaries per pixel for binary printing of a particular secondary; or (2) binary-printing the chromatic primary or secondary--but not other hues--after rendition, by use of a 'superpixel'; or (3) application of, in effect, a nonintegral number, greater than one, of ink drops per pixel; or (4) combinations of these treatments. As an example of the first of these treatments--using inks optimized for plain paper at one drop of ink for primaries and two (one of each of two primaries) for secondaries--red is printed on transparency film as one drop of yellow ink and two of magenta in each pixel. As to the second treatment, the superpixel is preferably a group of pixels (e.g., a two-by-two array) including the target pixel, in which group each pixel is inked and at least one pixel receives at least two drops of ink.

Inking for color-inkjet printers, using non-integral drop averages,

Color inkjet printers commonly employ a plurality of print cartridges, usually either two or four, mounted in the printer carriage to produce a full spectrum of colors. In order to optimize print quality, it is desirable to minimize the distance between a thermal inkjet printhead and the media that is being printed on. In a multiple printhead printer only one printhead can be the closest one to the media due to the various mechanical tolerances of the printer. Since black text print quality is more sensitive to printhead-to-media distance than is color graphics quality, the overall print quality of both black text and color graphics is optimized by assuring that the black print cartridge is closest to the media. Disclosed is a method for determining the relevant tolerances affecting printhead-to-media distance, analyzing the tolerance values to determine the range of tolerances and the greatest variation between one print cartridge and another, such that a determined percentage of the sampled print cartridges fall within this variation. This value is then used to offset the black print cartridge carriage slot so that the black print cartridge will be closest to the media.

Black text quality in printers using multiple black and color pens

A computer printer tray system comprising a paper input tray and a paper output tray, neither of which is required to have any moving parts. The output tray is supported in part by the input tray and both trays of the system are semi-permanently cantilever supported from the front of the printer so that neither tray has to be removed when loading an unprinted stack of cut sheet paper or removing printed paper. The output tray has a first portion which is inclined from a second portion by about 10.degree. to correct paper curl caused by a wet printing process.

Paper trays for computer driven printer

A wave isolator (18) is provided for large format drafting plotters (10) for preventing waves in the drafting medium (16) from traveling up the platen (14) and adversely affecting the pen (20) and its operation and reducing acceleration related vertical scalloping of angled lines. Such waves in the medium are generated by the motion of the paper during the plotting operation. The wave isolator comprises at least one strip (22a) of flexible material secured to the platen and of substantially the same length. Preferably, a polyimide film is used, having a coating of a thermoset acrylic resin with additives including conductive carbon black and polyethylene. In operation, when the medium is moving upward, the wave isolator deflects under the increased inertial load, and air trapped between the medium and the platen exits at the sides of the medium, dissipating some of its energy. When the medium is moving downward, the wave isolator sees a negative change in load and responds by flexing upward, tending to increase the volume of air between the medium and the platen, creating a low pressure area which sucks air in at the sides of the medium, again dissipating its energy. Use of the wave isolator of the invention permits high speed, high acceleration plotting on both sheet and roll media without the aid of firmware solutions.

Growing community of inventors

Davisville, WV, United States of America

Lance B Cleveland