Hewlett-Packard Company

Nicholas Nicoloff, Jr

Mark S Hickman

Majid Azmoon

Donald G Harris

John A Christianson

Douglas L Franz

Jay Wilson

Paul T Dubson

Stephen King Glass

Susan R Brassil

Clayton L Holstun

Thomas Michael Sabo

Joseph H Bauman

John M Skene

Gary M Nobel

In one embodiment of the invention, an inkjet printer selectively energizes ink ejection elements in a scanning printhead such that the top nozzles of the printhead do not always print the first line of text in a scan. In one embodiment, this is accomplished by occasionally aligning the bottommost nozzle in the printhead with the bottom of the last full line of text to be printed during the scan. The alignment of the printhead with respect to the lines of text to be printed is varied from page to page or varied at other intervals so that the top nozzles and bottom nozzles are used about equally. This will also cause more uniform wear of the middle nozzles. The more uniform wearing of the nozzles and ink ejection elements extends the life of the printhead. In inkjet printers using a black ink printhead which has a wider printing swath than one or more color ink printheads in the same scanning carriage, a new printing technique makes use of the nozzles in the wider printhead which extend beyond the shorter printhead when both printheads are being used during color printing.

Inkjet printing with uniform wear of ink ejection elements and nozzles

At least two different printmasks are used for different printing devices--such as inkjet pens--that operate concurrently, or different printing steps that proceed concurrently, to produce respective image swaths in a single, pixel-based printing machine. In one form of the invention, the different printing devices produce different respective pixel-row pitches (related to resolution) on a printing medium, and the different printmasks help to minimize adverse patterning effects that result from interaction of the different pitches with dot-placement errors. The different pitches on the print medium may be provided through different pitches of marking devices (for example, the number of inkjet nozzles per unit distance along a pen) or in other ways. In another form of the invention the different printing devices are provided with different respective liquid-base colorants, to mark in different colors on a printing medium, and the different masks facilitate physical separation of the different colorants to promote drying. Earlier-applied colorants have more time to dry and penetrate before later adjacent or superposed application of other colorants improving print attributes such as bleed, offset, cockle, curl, overall drying time and throughput.

Resolution-dependent and color-dependent print masking

At least two different pixel densities are used for different printing devices--such as inkjet pens--that operate concurrently, or different printing steps that proceed concurrently, to produce respective image swaths in a single, pixel-based printing machine. The different print devices or steps produce image swaths of respective different swath heights. In one form of the invention, the taller-swath-height printing device operates at lower pixel density, spreading its colorant over a greater area while printing-medium advance keeps pace with operation of the shallower-swath-height printing device. This procedure allows more drying and penetrating time for the colorant applied by the taller-swath device, thereby improving print attributes such as bleed, offset, cockle, curl, overall drying time and throughput. In another form of the invention the taller-swath device operates at higher pixel density, providing physical and temporal separation of colorant application from the two printing devices--to avoid adverse interfering effects between reactive inks.

Mixed-density print masking in a mixed-swath-height printer

In the preferred form, a scanning carriage in a color inkjet printer houses a high resolution printhead for black (or monochrome) printing and one or more lower resolution printheads for color printing. The nozzle arrangements, paper feed increments, and ink drop firing frequency for the black printhead and color printhead(s) are selected to provide various alignments between the larger color ink dots and the smaller black ink dots to achieve maximum ink coverage with a minimum of ink or to achieve additional color shades.

Dot alignment in mixed resolution printer

An inkjet printer is disclosed with mixed print resolution capabilities. The printed dots have a high resolution monochrome component such as black and lower resolution components such as cyan, magenta and yellow. For increased throughput, a higher resolution black printhead has a wider swath. Various alignments between the printheads and printed dots are disclosed. In one embodiment, the top edges of the smaller color printheads are aligned in a scanning carriage at or near the top of the wider black printhead. In other embodiments, the bottom edges of the smaller color printheads are aligned at or near the bottom of the wider black printhead. In another embodiment, the small color printheads are centered with the wider black printhead.

Alignment of differently sized printheads in a printer

In one embodiment of the invention, a scanning carriage in a color inkjet printer houses three identical color pens for printing cyan, magenta, and yellow. A separate array of nozzles is associated with each color ink. The nozzle arrays are such that they scan over the same print area of the medium during a single scan. To prevent the wet ink from one color swath being deposited over or bleeding into the wet ink from another color swath during the same scan, only a section of each nozzle array is used for printing during a single scan such that wet ink of two different colors cannot overlap during a single scan. This technique reduces ink bleed between colors as well as paper cockle. In another embodiment, a single tricolor pen is used where a single nozzle plate contains three nozzle arrays, one for each color. A section of each nozzle array is used during a single scan, as described above, to prevent wet ink of two different colors from overlapping during a single scan.

Simultaneously printing with different sections of printheads for

At least two different printmasks are used for different printing devices--such as inkjet pens--that operate concurrently, or different printing steps that proceed concurrently, to produce respective image swaths in a single, pixel-based printing machine. In one form of the invention, the different printing devices produce different respective pixel-row pitches (related to resolution) on a printing medium, and the different printmasks help to minimize adverse patterning effects that result from interaction of the different pitches with dot-placement errors. The different pitches on the print medium may be provided through different pitches of marking devices (for example, the number of inkjet nozzles per unit distance along a pen) or in other ways. In another form of the invention the different printing devices are provided with different respective liquid-base colorants, to mark in different colors on a printing medium, and the different masks facilitate physical separation of the different colorants to promote drying. Earlier-applied colorants have more time to dry and penetrate before later adjacent or superposed application of other colorants.

Growing community of inventors

La Mesa, CA, United States of America

Nicholas Nicoloff, Jr