Print data generation method, printing apparatus and method of generating mask

• US 7,878,613 B2
• Filed: 11/09/2006
• Issued: 02/01/2011
• Est. Priority Date: 12/01/2005
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Tajika, Hiroshi, Takamiya, Hideaki, Yoshikawa, Hirokazu, Konno, Yuji, Seki, Satoshi, Yano, Fumiko, Ide, Daisaku, Nishikori, Hitoshi, Yazawa, Takeshi, Mizoguchi, Yoshito
• Primary Examiner(s): HUFFMAN, JULIAN D
• Assistant Examiner(s): Garcia, Jr.; Rene
• Application Number:
  US11/558,324
• Publication Number:
  US 20070126789A1
• Time in Patent Office: 1,545 Days
• Field of Search: 347/15, 347/40, 347/14, 347/41, 347/43, 358/1.2, 358/1.9, 358 301- 303, 358/3.06, 358/501, 358/520
• US Class Current: 347/15
• CPC Class Codes: G06K 15/107 Mask selection

Abstract

Mask patterns to be used for multi-pass printing make it possible to make a print with a higher quality at a higher speed. Specifically, by performing a swapping process with adjacency forbiddance, two points in the horizontal direction, or the scanning direction of a printing head, are selected in a buffer in which codes for each scan pass are set depending on printing ratios of a gradation mask. Subsequently, codes are swapped between the two points. By this swap, adjacencies between print permitting areas are eliminated in the mask pattern. As a result, when driving frequencies set for the printing head is kept constant, the scanning speed can be doubled at minimum.

Claims

1. A method of generating print data for printing by a plurality of times of scanning of a print head arranging a plurality of nozzles to a given region on a print medium, said method comprising the step of:

generating print data for printing in each of the plurality of times of scanning, by thinning print data for printing on the given region with use of a plurality of mask patterns corresponding to the plurality of times of scanning, respectively,

wherein each of the plurality of mask patterns corresponding to the plurality of times of scanning arranges print permitting areas that permit printing based on the print data and print non-permitting areas that do not permit printing based on the print data in a scanning direction, in correspondence with each of the plurality of nozzles, and the print permitting areas are not adjacent to each other in the scanning direction,

wherein a ratio of the print permitting areas in the mask pattern corresponding to end nozzles of the printing head is smaller than a ratio of the print permitting areas in the mask pattern corresponding to central nozzles of the printing head, and

wherein each of the plurality of mask patterns arranges the print permitting areas aperiodically in the scanning direction.

2. A printing apparatus for printing by a plurality of times of scanning of a print head arranging a plurality of nozzles to a given region on a print medium, said apparatus comprising:

a generating unit that generates print data for printing in each of the plurality of times of scanning, by thinning print data for printing on the given region with use of a plurality of mask patterns corresponding to the plurality of times of scanning, respectively,

wherein each of the plurality of mask patterns corresponding to the plurality of times of scanning arranges print permitting areas that permit printing based on the print data and print non-permitting areas that do not permit printing based on the print data in a scanning direction, in correspondence with each of the plurality of nozzles, and the print permitting areas are not adjacent to each other in the scanning direction,

wherein a ratio of the print permitting areas in the mask pattern corresponding to end nozzles of the printing head is smaller than a ratio of the print permitting areas in the mask pattern corresponding to central nozzles of the printing head, and

wherein each of the plurality of mask patterns arranges the print permitting areas aperiodically in the scanning direction.

3. An ink jet printing apparatus which performs a plurality of times of scanning with a print head arranging a plurality of nozzles to a given region on a print medium to print thinned images with use of different nozzle groups of the print head for each of the plurality of times of scanning so that an image to be printed to the given region is completed, said apparatus comprising:

generating unit that generates print data for printing in each of the plurality of times of scanning, by thinning print data for printing on the given region with use of a plurality of mask patterns corresponding to a plurality of nozzle groups used in the plurality of times of scanning respectively; and

print controller that prints the thinned image with use of the nozzle group which is opposed to the given region based on the generated print data, in each of the plurality of times of scanning,

wherein each of the plurality of mask patterns arranges print permitting areas and print non-permitting areas so that a ratio of the print permitting areas corresponding to a nozzle at a part closer to an end of the nozzle arrangement is smaller than a ratio of the print permitting areas corresponding to a nozzle at a part closer to a center of the nozzle arrangement, and the print permitting areas are arranged to be not adjacent to each other and to be aperiodic, in a scanning direction, and

wherein a ratio of the print permitting areas in the mask pattern corresponding to the nozzle group including an end nozzle of the printing head are smaller than a ratio of the print permitting areas in the mask pattern corresponding to the nozzle group including no end nozzle.

4. An ink jet printing apparatus which performs a plurality of times of scanning with a print head arranging a plurality of nozzles to a given region on a print medium to print thinned images with use of different nozzles of the print head for each of the plurality of times of scanning so that an image to be printed to the given region is completed, said apparatus comprising:

convey device that conveys the print medium by an amount corresponding to one nozzle group of a plurality of nozzle groups that are made by dividing the plurality of nozzles in predetermined number of parts, in order to oppose each of the plurality of nozzle groups to the given region for each of the plurality of times of scanning;

generating unit that generates print data for printing in each of the plurality of times of scanning, by thinning print data for printing on the given region with use of a plurality of mask patterns corresponding to a plurality of nozzle groups used in the plurality of times of scanning respectively; and

print controller that prints the thinned image with use of the nozzle group which is opposed to the given region based on the generated print data, in each of the plurality of times of scanning,

wherein each of the plurality of mask patterns arranges print permitting areas and print non-permitting areas so that the farther from a central part of the nozzle arrangement along the nozzle arrangement, ratios of the print permitting areas become smaller, and the print permitting areas are arranged to be not adjacent to each other and to be aperiodic, in a scanning direction, and

wherein a ratio of the print permitting areas in the mask pattern corresponding to the nozzle group including an end nozzle of the printing head are smaller than a ratio of the print permitting areas in the mask pattern corresponding to the nozzle group including no end nozzle.