Hewlett-packard Company

Hewlett-packard Development Company, L.p.

Scott A Norum

Clayton L Holstun

Ronald Albert Askeland

James A Feinn

Jeffrey Allen Nielsen

Stefano Schiaffino

Stephen William Bauer

Matthew David Giere

Dustin W Blair

Mark D Lund

Paul David Gast

Xavier Gros

Jaime H Bohorquez

Jose Julio Doval

James L McCullough

Albert Serra

James Robert Schmedake

Robert W Sperry

A printhead for an inkjet printer having geometric features which reduce drop placement error of main and satellite drops ejected from the nozzles of the printhead. Nozzles that are tilted along an axis corresponding to the direction of scanning of the printhead while printing have reduced drop placement error in the orthogonal direction to the scanning, and create a breakoff velocity for the satellite drop that can cause the main and satellite drops to be placed in a coincident location on the medium in one of the directions of scanning, thus forming desireable round printed spots and reducing drop placement error in the scan direction. These improvements can be repeatably achieved for all nozzles. Nozzles with non-circular and asymmetric bores also reduce drop placement errors, particularly when these types of nozzles are also tilted.

Inkjet nozzle structure to reduce drop placement error

A misalignment compensation technique for a dot printer is disclosed. This technique first supplies printing instructions to a printhead for energizing printing elements in various groups (primitives) to print a pattern on a medium. The printed pattern is then detected by optical sensors in the printer. Based on the detection, a position offset error for each primitive is determined. These errors are used to generate a separate time correction for each of the primitives such that, when the printer is used normally, the time period for printing a dot will be advanced or delayed for each primitive so as to align the dots printed by the primitives. In another embodiment, alignment data taken by a manufacturing line sensor is stored in a memory on the print cartridge. After the print cartridge is installed in the printer, a second optical test completes the data needed to create timing correction values.

Alignment of ink dots in an inkjet printer

Disclosed is an inkjet print cartridge including an ink supply, a substrate having a plurality of individual ink ejection chambers defined by a barrier layer formed on a first surface of the substrate and having an ink ejection element in each of the ink ejection chambers, for ejecting drops of ink having a predetermined drop volume and drop velocity. The ink ejection chambers each have the same inlet channel length and are arranged in an array spaced so as to provide a predetermined resolution. A nozzle member having a plurality of ink orifices formed therein is positioned to overlie the barrier layer with the orifices aligned with the ink ejection chambers. An ink channel connects the reservoir with the ink ejection chambers. The inkjet print cartridge has several advantages of over previous printing systems in creating high quality images by using very small individual ink drops of low volume and high velocity. Highlight regions may be formed by using single low volume drops to form a dot. The individual drops are nearly invisible and can be used to form highlights with low graininess. As the density of the image increases, multi-drop dots are formed from two or more drops merging on the media to form a composite drop.

Apparatus for generating small volume, high velocity ink droplets in an inkjet printer

Data input received by a printer is printed. Dot data, which indicates location of dots on a print medium, is generated from the data input. Dot shift data is used in order to make sub-pixel shifts in locations of a subset of the dots on the print medium. Pulses are provided to a printhead which result in ink being emitted through nozzles located on the printhead. When placing the dots on the print medium, sub-pixel shifts in locations of the subset of the dots is achieved by time shifting the occurrence of pulses used to generate the dots.

Fractional dot column correction for scan axis alignment during printing

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La Jolla, CA, United States of America

Scott A Norum