Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-02-14
2002-09-17
Nguyen, Thinh (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S019000
Reexamination Certificate
active
06450611
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the invention
The present invention relates to optimizing carrier movement in an ink jet printer, and, more particularly, to optimizing carrier movement in an ink jet printer with a minimum of memory.
2. Description of the Related Art
A significant performance problem with an ink jet printer is unnecessary carrier movements on a page. Unnecessary carrier movements may result from excess carrier motion at the beginning and end of any given swath or from non-optimal form advancement between swathes. Each of these unnecessary delays causes a reduction in print performance.
On an ink jet printer, printing the job in an optimal time requires knowledge about the characteristics of the current swath being printed plus the next swath. Precise swath prediction requires expansion of the next swath into memory before boundary calculations can be performed. Unfortunately, on a printer that is constrained by memory, it may be impossible to expand more than one swath at a time.
To move the carrier optimally, a way is needed to determine information about the subsequent swath to be printed. On a standard page printer that typically expands the entire page into a bitmap before printing, this would not be a problem, as all of the detailed information for the next swath would be available before launching the current swath. Unfortunately, on a printer that is constrained by memory, it may be impossible to expand more than one swath at a time. The current swath must remain resident in memory until it has completely printed. Therefore, what is needed is a method of predicting the margins for the next swath to be printed which requires less memory or processor bandwidth without significantly sacrificing accuracy of the predicted margins. This predictive data must also contain the information needed to compute optimal form indexing needed to advance the paper beyond white space.
What is needed in the art is a method of minimizing delays resulting from unnecessary carrier movements by optimizing form indexing and carrier movement throughout the page. More particularly, a method is needed to predict the boundaries of the next swath that requires little memory or processor bandwidth without significantly sacrificing accuracy of the predicted boundaries.
SUMMARY OF THE INVENTION
The present invention provides a method of identifying boundaries of a swath to be printed by an ink jet printer with a minimum of memory so that carrier movements can be optimized.
The invention comprises, in one form thereof, a method of positioning an ink jet printhead in a printer. A bitmap is divided into a plurality of rows of tiles. A subset of the rows of tiles to be printed in a next pass of the printhead is identified. Printable ones of the tiles in the subset of rows are identified. The printable tiles contain printable data. Within each printable tile, a top most location of the printable data and at least one of a left most location of the printable data and a right most location of the printable data are identified. A print medium is advanced in a feed direction until a portion of the print medium corresponding with the top most location of the printable data of at least one printable tile is substantially aligned with a top nozzle of the printhead. The printhead is moved, in a scan direction, directly to a position on the print medium corresponding to one of the left most location of the printable data of at least one printable tile and the right most location of the printable data of at least one printable tile.
An advantage of the present invention is that carrier movements in an ink jet printer are optimized while using a minimum of memory and processor bandwidth.
Another advantage is that predicted margins are more accurate.
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Brown, Jr. Martin Joseph
Hoang Cuong Manh
Langer David Brian
Murphy David William
Overall Gary Scott
Barker Scott N.
Lambert D. Brent
Lexmark International Inc.
Nguyen Thinh
Taylor & Aust P.C.
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