Hewlett-packard Company

Irene H Williams

Daniel R Tretter

Robert D Haselby

Gerold G Firl

Steven Ray Card

Lowell J Stewart

Cindy Y Sansom-Wai

Curt Behrend

Edward D Davis

A system and method is described for automatically determining in a scanned document image the presence of unwanted extraneous information caused by an extraneous device and scanner background information. Once the presence of this information is determined, the system and method of the present invention can compute, for instance, skew and crop statistics. From this, the image can be automatically deskewed and cropped appropriately without the background and extraneous information. The system and method accomplishes this by first determining the presence of unwanted extraneous and background information and then appropriately processing the document image. The extraneous information is ignored during deskew and crop computations. Also, the scanner background and the extraneous information are prevented from being included in the final digital representation of the image.

Image processing system with image cropping and skew correction

Signals indicating ink-discharge presence control priming and preferably halt document creation pending ink resupply--or pending an operator command to go on without resupply. A detector senses ink discharge; circuits including a programmed microprocessor apply the detector signal to control, most typically, pen priming or repriming--and preferably related functions including suspension of printer operation. The detector preferably includes an optical source and detector along an optical path that intersects an ink-discharge path. With a pen that has multiple ink-discharge nozzles, preferably the apparatus distinguishes between ink discharge from the different nozzles (by correlation with nozzle-actuating pulses), and accordingly controls priming of each nozzle independently. Preferably this system is operated before starting to print a new sheet and upon newly installing a pen. In event of inadequate ink discharge, progressively more-energetic priming impulses (higher voltage or duration, or both) are directed to the pen, until adequate discharge results or no further energy increase is deemed suitable.

Apparatus for enhancing ink-flow reliability in a thermal-inkjet pen;

A process for start up of a thermal ink-jet printhead cartridge that includes a sequence of nozzle clearing procedures of increasing severity which are performed in sequence so long as some of the nozzles of the printhead fail to fire ink drops pursuant to ink firing pulses provided to the printhead or until all of the procedures have been performed.

Pen start up algorithm for black and color thermal ink-jet pens

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Escondido, CA, United States of America

Irene H Williams