Hewlett-Packard Company

Eva-Maria Moon

Steven B Elgee

Paul David Gast

Alan Shibata

Thomas B Pritchard

Eric L Ahlvin

Shane D Wall

A method adapted for implementation in a computer system for correcting and half toning color data in a list of colors is provided. Starting with the first color in the list, color corrections are performed. Using traditional half toning methods, descriptions of the resulting printable dots for each position in the halftone matrix for that color are determined. Color corrections and half toning are repeated for each of the colors in the list. A lookup table is compiled. As each pixel of the image from which the list of colors was compiled is encountered, the printable dots are determined by reference to the lookup table.

Computerized memory mapping method for transforming color data

Automatic print rate-controlling and pen-servicing method and apparatus are described for power management and for determining appropriate servicing intervals for plural-pen ink-jet printers. The preferred method involves counting the number of drops of ink that are fired from each of plural pens in the printer's printhead carriage and optionally calculating the pen firing rate such that printer throughput can be controlled to limit time-averaged power and such that pen servicing frequency can be based upon the need for such servicing. The counts are maintained in memory connected, for example, with the printer's microcontroller, as are parameters that the microcontroller uses to determine appropriate drop count-based print rate controlling or pen servicing that reduce printer throughput only to the extent necessary. Particularly, the pens are serviced when any of the counts is within a predefined finite range of a predefined number or no later than when any of the counts exceeds a corresponding predefined number. The preferred apparatus includes a drop counter, a service station for wiping and spitting plural pens within a printhead carriage and a controller responsive to the drop counter to control the printing rate and to move the printhead carriage into operative association with the service station based upon drop count, firing rate, time-averaged power capability, printhead location and other predetermined criteria.

Drop count-based ink-jet pen servicing method

Bidirectional interleaving of tri-color and black ink-jet pen print pass carriage retrace periods by the invention are utilized whenever possible for black printing. Preferably, printer controller logic used to determine next print direction monitors and records a most recent, or last, black print direction indicium such as a flag stored in memory. If certain predetermined last black print direction criteria are met, the next black print pass is performed in the opposite direction from that of the most recent color print pass, thereby increasing printer throughput. In accordance with the invention, typical tricolor and black printed swaths require up to three color print passes, one black print pass during retrace and only two non-printing retraces, thereby saving time and motion that otherwise would be wasted performing two additional, non-printing retraces.

Bidirectional black and color pass print method for ink-jet printers

A synchronized wiper and pen motion solution for ink-jet printers is described. The invented method and apparatus synchronize the motion of the pen and wiper throughout the wipe stroke, and provide for controlled, simultaneous movement therebetween that avoids pole vaulting, excess interference and ink flicking. Such is accomplished by moving the carriage to a defined position shy of a wiping position above the service station including a sled mounting the wiper; raising the sled to produce a proper interference fit between the wiper and the pen while simultaneously moving the carriage at low speed; continuing the wipe stroke by high-speed carriage movement with the sled stationary; and, at the end of the stroke, lowering the sled to clear the wiper from contact with the pen before reversing carriage motion. The solution lends itself to single- or plural-pen ink-jet printers.

Synchronized carriage and wiper motion method and apparatus for ink-jet

Carriage and paper motion overlap method and apparatus are described. The preferred method utilizes carriage ramp-down and unidirectional, constant-speed periods of time to advance paper via the printer's paper advancement mechanism while avoiding current-intensive ramp-up periods of time during which demands on the printer's power supply are high. The printer's controller is programmed to implement preferably concurrently operable processes one of which controls paper movement and the other of which controls carriage movement. The processes signal one another based upon their monitoring of defined conditions of the printer and the print buffer, and by setting and clearing a flag.

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Washougal, WA, United States of America

Eva-Maria Moon