Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
2000-03-24
2001-11-20
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Controller
C347S043000
Reexamination Certificate
active
06318832
ABSTRACT:
FIELD OF THE INVENTION
The present invention is generally directed to forming images consisting of patterns of dots. The invention is more particularly directed to high-resolution inkjet printing based on multiple interlaced patterns of dots.
BACKGROUND OF THE INVENTION
An inkjet printer forms an image on a print medium by placing a pattern of dots on the medium. Possible dot locations are represented by an array or grid of pixels that are arranged in a rectilinear array of rows and columns. The center-to-center distance between pixels, or dot pitch, is determined by the resolution of the printer. For example, for a printer capable of printing 300 dots per inch (dpi), the dot pitch of the array is {fraction (1/300)} of an inch.
The quality of printed images produced by an inkjet printer depends in part on the resolution of the printer. Typically, higher or finer resolutions, where the printed dots are more closely spaced, results in higher quality images. Increasing the resolution of an inkjet printer increases the number of dots to be printed in a unit area by the product of the increase factor in each dimension in the grid. For example, doubling the print resolution from 300 to 600 dpi in a square grid results in four times as many dots per unit area. Consequently, without a decrease in dot size, four times as much ink would be printed in the same area. If too much ink is printed in a given area, the print medium can become saturated. Ink saturation can cause smudging and wrinkling of the medium.
One way to avoid saturating a print medium when printing dots that are larger than optimal for the grid resolution is to reduce the size of each dot. However, significant reductions in dot size may be extremely difficult, if not impractical, to achieve.
Addressing and placing a dot of ink at every pixel location in a high-resolution grid requires many redundant nozzles, very slow print head travel across the medium, or very high firing frequency. With each of these options there is either increased cost, slowed performance, or difficult technical challenges.
Therefore a method of printing is needed that provides high-resolution printing using a dot size that is larger than optimal for the grid resolution, while avoiding ink saturation of the print medium.
Further, true high-resolution printing involves large amounts of image data. For example, 1200×1200 dpi printing involves four times as much data as 600×600 dpi printing. The standard parallel port interface between a host computer and a printer can become a data bottleneck when transferring high-resolution print data to the printer. Faster and more efficient methods of transferring print data from the host computer to the printer are needed.
SUMMARY OF THE INVENTION
The foregoing and other needs are met by an ink jet printer that receives image data defining a pattern of dots in a rectangular grid and that prints the pattern of dots on a print medium based on the image data. The printer includes a print medium advance mechanism for advancing the print medium in a first direction. The printer also includes a print head having multiple nozzles for ejecting ink droplets onto the print medium to print the dots. The center-to-center spacing in the first direction between the nozzles is represented by d. A carriage connected to the print head moves the print head adjacent the print medium in a second direction which is perpendicular to the first direction. A carriage drive mechanism connected to the carriage drives the carriage in the second direction. A printer controller is electrically connected to the print head, the print medium advance mechanism, and the carriage drive mechanism. The controller controls the print head to eject ink droplets from the nozzles toward the print medium, controls the print medium advance mechanism to advance the print medium in the first direction, and controls the carriage drive mechanism to move the carriage in the second direction. The ejection of ink droplets, advancement of the print medium, and movement of the carriage under control of the printer controller forms the pattern of dots on the medium consisting of at least four interlaced arrays of dots. Each of the arrays is offset from the other arrays by a predetermined spacing in at least one of the first and second directions.
In preferred embodiments of the invention, the printer prints four interlaced checkerboard arrays of dots in four passes of the print head in the second direction across the print medium, where each one of the four checkerboard arrays is printed during a different one of the four passes. In some preferred embodiments, the printer prints the second checkerboard array offset from the first checkerboard array in the second direction by a distance substantially equivalent to {fraction (5+L d/4+L )}. The printer prints the third checkerboard array offset from the second checkerboard array in the first direction by a distance substantially equivalent to {fraction (−d/2+L )} and in the second direction by a distance substantially equivalent to {fraction (−3+L d/4+L )}, and prints the fourth checkerboard array offset from the third checkerboard array in the second direction by a distance substantially equivalent to {fraction (−3+L d/4+L )}.
This dot placement method optimally covers a grid having a resolution of {fraction (4+L /d)}×{fraction (2+L /d )} dpi with dots having diameters that are much larger than optimal for the resolution of the grid. Thus, the invention avoids excessive dot overlap which could lead to ink saturation of the print medium.
In other preferred embodiments of the invention, the printer prints the pattern of dots consisting of first, second, third, and fourth interlaced arrays of dots. Each of the arrays has parallel columns of dots aligned in the first direction and parallel rows of dots aligned in the second direction. Adjacent dots in each column have a center-to-center spacing in the first direction substantially equivalent to d, and adjacent dots in each row have a center-to-center spacing in the second direction substantially equivalent to d. The second array of dots is offset from the first array in the first and second directions by a distance substantially equivalent to {fraction (d/2+L )}. The third array is offset from the second array in the first direction by a distance substantially equivalent to {fraction (d/2+L )}. The fourth array is offset from the third array in the first and second directions by a distance substantially equivalent to {fraction (d/2+L )}.
REFERENCES:
patent: 3977007 (1976-08-01), Berry et al.
patent: 4575730 (1986-03-01), Logan et al.
patent: 4642653 (1987-02-01), Ito et al.
patent: 5270728 (1993-12-01), Lund et al.
patent: 5321432 (1994-06-01), Ishikawa et al.
patent: 5359355 (1994-10-01), Nagoshi et al.
patent: 5416612 (1995-05-01), Ingraham et al.
patent: 5430469 (1995-07-01), Shioya et al.
patent: 5469198 (1995-11-01), Kadonaga
patent: 5500661 (1996-03-01), Matsubara et al.
patent: 5574832 (1996-11-01), Towery et al.
patent: 5583550 (1996-12-01), Hickman et al.
patent: 5602572 (1997-02-01), Rylander
patent: 5642142 (1997-06-01), Bohorquez
patent: 5648801 (1997-07-01), Beardsley et al.
patent: 5675365 (1997-10-01), Becerra et al.
patent: 5677714 (1997-10-01), Klassen et al.
patent: 5696542 (1997-12-01), Matsubara et al.
patent: 5719601 (1998-02-01), Moore et al.
patent: 5731827 (1998-03-01), Mantell et al.
patent: 5742300 (1998-04-01), Klassen
patent: 5754192 (1998-05-01), Sugaya
patent: 5767870 (1998-06-01), Klassen et al.
patent: 5818488 (1998-11-01), Tanuma et al.
patent: 0 516 420 B1 (1996-08-01), None
patent: 0 556 959 B1 (1998-07-01), None
Bates John Booth
Breswick Curt Paul
Crockett Mark P.
Le N.
Lexmark International Inc.
Nguyen Lamson D.
Pezdek John Victor
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