Ink jet printing apparatus and method

• US 9,050,821 B2
• Filed: 12/02/2010
• Issued: 06/09/2015
• Est. Priority Date: 12/09/2009
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Konno, Yuji, Murayama, Yoshiaki
• Primary Examiner(s): Le, Uyen Chau N
• Assistant Examiner(s): Smith, Chad
• Application Number:
  US12/958,805
• Publication Number:
  US 20110134177A1
• Time in Patent Office: 1,650 Days
• Field of Search: 347/41
• US Class Current: 1/1
• CPC Class Codes: B41J 2/2125 by means of nozzle diameter selection
• CPC Class Codes: B41J 2/2132 Print quality control characterised by dot disposition, e.g. for reducing white stripes or banding methods for local corrections by dot omission, image edge enhancement, or multi-pass mask selection G06K15/102; colour conversion H04N1/40
• CPC Class Codes: G06K 15/107 Mask selection

Abstract

Through the use of a mask with an appropriate pattern, depending on dot size or density, in an in jet printing apparatus, image defects caused by conveyance distance errors are suppressed. More concretely, at the masking unit A an interlaced mask pattern is used and a masking process is performed with respect to 2 pl dot data obtained from the dot pattern development unit 604. On the other hand, at the masking unit B a random mask pattern is used and masking is performed with respect to 5 pl dot data. Herewith it has become possible, at all gradations, to suppress the 2 image defects, density unevenness and graininess, caused by conveyance distance errors.

Claims

1. An ink jet printing apparatus, which uses a print head provided with ejection ports that eject ink drops having a first size and that are arranged in a sub-scanning direction, and ejection ports that eject ink drops having a second size larger than the first size and that are arranged in the sub-scanning direction, and performs printing an image by relative scanning of the print head and the print medium in a main-scanning direction crossing to the sub-scanning direction, comprising:

a printing unit configured to print the image to a predetermined region on the print medium by a plurality of scans of the print head; and

a generating unit configured to generate first print data for ejecting ink drops having the first size for each of the plurality of scans by using a first mask pattern and generate second print data for ejecting ink drops having the second size for each of the plurality of scans by using a second mask pattern,

wherein a number of low frequency components of a spatial frequency characteristic shown by an arrangement of print permitted pixels in the second mask pattern is lower than a number of low frequency components of a spatial frequency characteristic shown by an arrangement of print permitted pixels in the first mask pattern.

2. The printing apparatus according to claim 1, wherein the first mask pattern has a random pattern of print permitted pixels and the second mask pattern has an interlaced pattern of print permitted pixels, and in the interlaced pattern, print permitted pixels are consecutively arranged in the main-scanning direction and are not consecutively arranged in the sub-scanning direction.

3. An ink jet printing apparatus that, during a relative movement of a print head in a main-scanning direction, which comprises a first ejection port array, in which a plurality of ejection ports that eject first ink drops are arranged in a sub-scanning direction, and a second ejection port array, in which a plurality of ejection ports that eject second ink drops having a size larger than that of the first ink drops are arranged in the sub-scanning direction, performs printing by ejecting the first ink drops and the second ink drops onto the print medium from the print head, comprising:

a generation unit configured to generate first print data for ejecting the first ink drops to be printed to a predetermined region of the print medium for each of a plurality of relative movements of the print head by using a first mask pattern and generate second print data for ejecting the second ink drops to be printed to the predetermined region for each of the plurality of relative movements of the print head by using a second mask pattern; and

a printing unit configured to print the image to the predetermined region based on the first and second print data generated by the generation unit,

wherein the print permitted pixels of the first mask pattern are arranged non-periodically, and

the print permitted pixels of the second mask pattern are arranged periodically.

4. The printing apparatus according to claim 3, wherein the arrangement pattern of print permitted pixels in the first mask pattern is a random pattern and the arrangement pattern of print permitted pixels in the second mask pattern is an interlace pattern, and in the interlaced pattern, print permitted pixels are consecutively arranged in the main-scanning direction and are not consecutively arranged in the sub-scanning direction.

5. An ink jet printing method, in which a print head provided with ejection ports that eject ink drops having a first size and that are arranged in a sub-scanning direction and ejection ports that eject ink drops having a second size larger than the first size and that are arranged in the sub-scanning direction is used, for performing printing an image by relative scanning of the print head and the print medium in a main-scanning direction crossing to the sub-scanning direction, comprising:

a step that provides a printing unit configured to print the image to a predetermined region on the print medium by a plurality of scans of the print head; and

a step for generating first print data for ejecting ink drops having the first size for each of the plurality of scans by using a first mask pattern and generating second print data for ejecting ink drops having the second size for each of the plurality of scans by using a second mask pattern,

wherein a number of low frequency components of a spatial frequency characteristic shown by an arrangement of print permitted pixels in the second mask pattern is lower than a number of low frequency components of a spatial frequency characteristic shown by an arrangement of print permitted pixels in the first mask pattern.

6. An ink jet printing method that, during a relative movement of a print head in a main-scanning direction, which comprises a first ejection port array, in which a plurality of ejection ports that eject first ink drops are arranged in a sub-scanning direction, and a second ejection port array, in which a plurality of ejection ports that eject second ink drops having a second size larger than the first size are arranged in the sub-scanning direction, performs printing an image by ejecting the first ink drops and the second ink drops onto the print medium from the print head, comprising:

a generation step for generating first print data for ejecting the first ink drops to be printed to a predetermined region of the print medium for each of a plurality of relative movements of the print head by using a first mask pattern and generating second print data for ejecting the second ink drops to be printed to the predetermined region for each of a plurality of relative movements of the print head by using a second mask pattern; and

a printing step for printing the image to the predetermined region based on the first and second data generated at the generation step,

wherein the print permitted pixels of the first mask pattern are arranged non-periodically, and

the print permitted pixels of the second mask pattern are arranged periodically.

7. An ink jet printing apparatus, which uses a print head provided with ejection ports that eject ink drops having a first size and that are arranged in a sub-scanning direction, and ejection ports that eject ink drops having a second size larger than the first size and that are arranged in the sub-scanning direction, and performs printing an image by relative scanning of the print head and the print medium in a main-scanning direction crossing to the sub-scanning direction, comprising:

a printing unit configured to print an image to a predetermined region on the print medium by a plurality of scans of the print head; and

a generating unit configured to generate first print data for ejecting ink drops having the first size for each of the plurality of scans by using a first mask pattern and generate second print data for ejecting ink drops having the second size for each of the plurality of scans by using a second mask pattern,

wherein the first mask pattern has a random pattern of print permitted pixels and the second mask pattern has an interlaced pattern of print permitted pixels, and in the interlaced pattern, dots are consecutively arranged in the main-scanning direction and not consecutively arranged in the sub-scanning direction.