Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
2001-10-01
2003-05-13
Nguyen, Thinh (Department: 2853)
Incremental printing of symbolic information
Ink jet
Controller
C347S043000
Reexamination Certificate
active
06561610
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a technique for printing images on a print medium by ink ejection.
2. Description of the Related Art
Ink-jet printers for forming ink dots into images on print media by ejecting ink droplets are widely used as devices for outputting images created by computers and digital cameras.
When non-picture image such as characters, illustrations, and line drawings are printed by an ink-jet printer, the ink sometimes bleeds along the outlines of the non-picture image. Such ink bleeding is attributed to the fact that the ink ejected into the line-drawing area accumulates without being absorbed by the print medium, and flows out toward the areas not intended to form dot therein.
In particular, ink dots tend to elongate in the direction of main scanning when they are formed while the print head is moved in the direction of main scanning, so contour lines extending parallel to the direction of main scanning are prone to ink accumulation and bleeding. Contour lines extending parallel to the direction of higher resolution are also apt to accumulate ink when different resolutions are set for the directions of main and sub-scan. Not only does such bleeding affect the outline portions, but it sometimes occurs in cases in which differently colored high-concentration regions are brought close together to form an outline.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to reduce ink bleeding in outline portions in a printing device for printing images by ejecting ink droplets.
In order to attain the above and the other objects of the present invention, there is provided a printing control apparatus for generating print data to be supplied to a printing unit to perform printing during main scans. The printing control apparatus comprises: a dot data generator, a contour line extractor, and a dot data adjuster. The dot data generator is configured to generate dot data from image data indicative of a image to be printed, where the dot data representing a state of dot formation in each pixel. The contour line extractor is configured to extract a first type contour line of a specific type image area represented by the dot data, where the first contour line is parallel to a main scan direction, and the specific type image area is composed of pixels at which specific type dots are to be formed. The dot data adjuster is configured to adjust the dot data so as to regularly reduce an amount of ink for forming dots on the first contour line.
Therefore, it is possible to reduce bleeding from the outlines of a printed image, because the amount of ink is regularly reduced for the ink dots needed to form contour lines disposed parallel to the direction of main scanning, where bleeding is apt to occur. As a result, texts and other printed images having sharply defined outlines can be printed with high legibility.
In a preferred embodiment of the invention, the dot data adjuster is configured to adjust the dot data so as to reduce the amount of ink by selectively performing one of dot skipping and dot size reduction, depending on a pixel position of each dot within the specific image area.
This arrangement is advantageous in that sharply defined outlines can be obtained within a range devoid of ink bleeding because the amount of ink can be reduced in a more controlled manner.
In another embodiment, a printing control apparatus for generating print data to be supplied to a printing unit capable of printing images on print medium with multiple print resolution, the printing control apparatus comprising: a dot data generator configured to generate dot data from image data indicative of a image to be printed, the dot data representing a state of dot formation in each pixel; a contour line extractor configured to extract a transverse contour line parallel to a main scan direction of an image area composed of pixels at which a specific type dot to be formed by the dot data, the specific type dot being defined by the fact that a first value is greater than the predetermined first threshold, the first value being obtained by dividing the length of the specific type dot in a main scan direction by the pixel length in the main scan direction, assuming that the specific type dot is formed individually; and a dot data adjuster configured to adjust the dot data so as to regularly reduce an amount of ink for forming dots on the transverse contour line.
In the other embodiment, a printing control apparatus for generating print data to be supplied to a printing unit to perform printing during main scans, the printing unit comprising a print head having a plurality of nozzles and a plurality of ejection driving elements for causing ejection of ink droplets respectively from the plurality of nozzles, each nozzle being adaptable to form a selected one of N different dots having different sizes in one pixel area on the print medium, N being an integer of at least 2, the N different dots including a specific size dot that is one of comparatively large dots among the N different dots; and a dot data generator configured to generate dot data from image data indicative of a image to be printed, the dot data representing a state of dot formation in each pixel; a contour line extractor configured to extract a contour line of a specific type image area represented by the dot data, the specific type image area being composed of pixels at which specific size dots are to be formed; and a dot data adjuster configured to adjust the dot data so as to reduce the amount of ink by reducing dot size when the contour line is formed with the specific size dot.
The present invention can be realized in various forms such as a method and apparatus for printing, a method and apparatus for producing print data for a printing unit, and a computer program product implementing the above scheme.
REFERENCES:
patent: 5136401 (1992-08-01), Yamamoto et al.
patent: 5596352 (1997-01-01), Bliss et al.
patent: 5633662 (1997-05-01), Allen et al.
patent: 5872896 (1999-02-01), Li et al.
patent: 6099104 (2000-08-01), Sato et al.
patent: 0628415 (1994-12-01), None
patent: 10-250119 (1998-09-01), None
Sato Akito
Yamasaki Keigo
Beyer Weaver & Thomas LLP
Nguyen Thinh
Seiko Epson Corporation
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