Lexmark International, Inc.

David Keith Lane

Randall David Mayo

John Philip Bolash

Thomas Jon Eade

Cary Patterson Ravitz

Julie Ann Gordon Whitney

Ning Ren

Raymond Edward Clark

Stanley Coy Tungate, Jr

Curt Paul Breswick

Robert Jerome Borchers

Howard Charles Cochran

Steven Lane Duncan

David Steven Waldrop

Erik Nils Ackerman

An improved color EP (laser) printer is provided for use in high humidity conditions. A humidity sensing circuit determines if the print quality might be degraded due to environmental conditions, using a resistivity sensing circuit, or a humidity sensor. If the print quality would likely be degraded, the invention is able to enhance toner transfer by printing supplemental process black toner dots underlaying standard black toner dots at predetermined pixel locations in the bitmap of a print job. This assumes that the black printing station is the 'last' station along the travel of the intermediate transfer member. Other colors could be used for the supplemental toner dots.

Black print quality enhancement for high humidity environment

Methods and systems for estimating single or multi-colored toner coverage on a printed page. One method includes generating color plane bitmaps corresponding to each color in a contone bitmap and calculating pixel coverage values for each of the color plane contone bitmaps. Another method includes receiving image data to be printed, generating color separations for the image data corresponding to available toner colors, printing each color separation on a printed page, scanning each printed page comprising the color separation and calculating toner coverage on each of the scanned printed pages.

Methods and systems for estimating single or multi-color toner coverage on a printer page

The present invention is directed a method of color trapping. In one embodiment, the color trapping is performed during the rasterization process. The color trapping comprises identifying page objects into a variety of different categories. Color trapping for each of the page objects is then performed based on specific procedures for the category. In one embodiment, the categories include identifying the page objects as rectangles, characters, and non-rectangular shapes. In one embodiment, specific page objects may be identified as being of a type that color trapping is not to be performed.

Color trapping for an image forming apparatus

A printer is provided which has a special Emulation Manager function as well as a &ldquo;code sniffer&rdquo; function, in which print data received is sent to a code sniffer buffer. A code sniffer function automatically determines the type of emulator that should be called to perform the interpretation or rendering of this print job, and if the code sniffer determines that the correct emulator is PostScript, then the code sniffer scans the data for any &ldquo;special tokens.&rdquo; If a special token is found, the PostScript emulator determines if the special token string data is part of a PostScript comment. If it is in the correct format, then the PostScript emulator sets the &ldquo;mode flag&rdquo; to the &ldquo;MacBinary&rdquo; state, and the code sniffer ceases any further filtering of control characters and disables any change of emulator command that may be received during this print job. The rest of the print job is then interpreted as RAW binary data by the PostScript emulator, until a &ldquo;UEL&rdquo; string is encountered.

Method for automatically detecting and processing binary postscript print jobs

A print quality enhancement arrangement for a dot matrix printer such as a thermal ink jet printer. The arrangement includes a buffer for receiving 300 dots per inch (dpi) resolution data in the horizontal (print head movement) direction and creates 600 dpi resolution data using image enhancement techniques. The arrangement further includes correction of the higher resolution data to remove pels which are unprintable due to the frequency response of the print elements in the print head. The correction is performed using knowledge of the history of printed pels and the original 300 dpi data. The creation of the higher resolution data and its correction occur 'on-the-fly' as data is being fed to the print head, rather than through the creation of a 300 by 600 dpi bitmap.

Print quality enhancement method and apparatus

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Stamping Ground, KY, United States of America

David Keith Lane