INK JET PRINTING APPARATUS AND METHOD

• US 20110134177A1
• Filed: 12/02/2010
• Published: 06/09/2011
• Est. Priority Date: 12/09/2009
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Murayama, Yoshiaki, Konno, Yuji
• Granted Patent: US 9,050,821 B2
• Time in Patent Office: Days
• US Class Current: 347/14
• 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 capable of forming dots of a first size on a print medium and ejection ports that eject ink capable of forming dots of a second size, larger than the first size, on the print medium, and performs printing by ejecting ink onto the print medium based on print data, comprising:

a multi-pass printing unit that executes the printing of a predetermined region by a plurality of scans of the print head in relation to the print medium; and

a masking unit for generating thinned print data for each of the plurality of scans by masking the print data of the predetermined region using a mask,

wherein said masking unit performs masking of the print data for forming the dots of the first size using a first mask pattern and performs masking of the print data for forming the dots of the second size using a second mask pattern in which the arrangement pattern of print permitted pixels has a lower number of low frequency components than that of the first mask pattern.

3. The printing apparatus according to claim 1 or claim 2, 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.

2. An ink jet printing apparatus, which uses a print head provided with ejection ports that eject ink capable of forming dots of a first density on a print medium and ejection ports that eject ink capable of forming same-colored dots of a second density, higher than the first density, on the print medium, and performs printing by ejecting ink onto the print medium based on print data, comprising:

a multi-pass printing unit that executes the printing of a predetermined region by a plurality of scans of the print head in relation to the print medium; and

a masking unit for generating thinned print data for each of the plurality of scans by masking the print data of the predetermined region using a mask,

wherein said masking unit performs masking of the print data for forming the dots of the first density using a first mask pattern and performs masking of the print data for forming the dots of the second density using a second mask pattern in which the arrangement pattern of print permitted pixels has a lower number of low frequency components than that of the first mask pattern.

4. An ink jet printing apparatus that, during a relative movement of a print head, which is capable of ejecting first ink drops and second ink drops of either a different ejection volume or a different color than the first ink drops, in relation to a print medium, performs printing by ejecting the first ink drops and the second ink drops onto the print medium from the print head, comprising:

a data generation unit that, using a mask pattern on which print permitted pixels and non-print permitted pixels are arranged, generates, from image data to be printed at the same region of the print medium, image data to be printed at each of a plurality of relative movements of the print head; and

a printing unit that performs printing at the same region based on image data generated by the data generation unit,

wherein the print permitted pixels of the mask pattern for generating image data rendering the image to be printed by the first ink drops at the same region are arranged non-periodically, and

the print permitted pixels of the mask pattern for generating image data rendering the image to be printed by the second ink drops at the same region are arranged periodically.

5. The printing apparatus according to claim 4, wherein the ejection volume of the second ink drops is greater than that of the first ink drops.

6. The printing apparatus according to claim 4 or claim 5, wherein the second ink drops have a higher color concentration than the first ink drops.

7. An ink jet printing method, in which a print head provided with ejection ports that eject ink capable of forming dots of a first size on a print medium and ejection ports that eject ink capable of forming dots of a second size, larger than the first size, on the print medium is used, for performing printing by ejecting ink onto the print medium based on print data, comprising:

a step that provides a multi-pass printing unit to execute the printing of a predetermined region by a plurality of scans of the print head in relation to the print medium; and

a masking step for generating thinned print data for each of the plurality of scans by masking the print data of the predetermined region using a mask,

wherein said masking step performs masking of the print data for forming the dots of the first size using a first mask pattern and performs masking of the print data for forming the dots of the second size using a second mask pattern in which the arrangement pattern of print permitted pixels has a lower number of low frequency components than that of the first mask pattern.

8. An inkjet printing method, in which a print head provided with ejection ports that eject ink capable of forming dots of a first density on a print medium and ejection ports that eject ink capable forming same-colored dots of a second density, higher than the first density, on the print medium is used, for performing printing by ejecting ink onto the print medium based on print data, comprising:

a step that provides a multi-pass printing unit to execute the printing of a predetermined region by a plurality of scans of the print head in relation to the print medium; and

a masking step for generating thinned print data for each of the plurality of scans by masking the print data of the predetermined region using a mask,

wherein said masking step performs masking of the print data for forming the dots of the first density using a first mask pattern and performs masking of the print data for forming the dots of the second density using a second mask pattern in which the arrangement pattern of print permitted pixels has a lower number of low frequency components than that of the first mask pattern.

9. An ink jet printing method that, during a relative movement of a print head, which is capable of ejecting first ink drops and second ink drops of either a different ejection volume or a different color than the first ink drops, in relation to a print medium, performs printing by ejecting the first and second ink drops onto the print medium from the print head, comprising:

a data generation step that, using a mask pattern on which print permitted pixels and non-print permitted pixels are arranged, generates, from image data to be printed at the same region of the print medium, image data to be printed at each of a plurality of relative movements of the print head; and

a printing step that performs printing at the same region based on image data generated at the data generation step,

wherein the print permitted pixels of the mask pattern for generating image data rendering the image to be printed by the first ink drops at the same region are arranged non-periodically, and

the print permitted pixels of the mask pattern for generating image data rendering the image to be printed by the second ink drops at the same region are arranged periodically.