# US 8,770,693 B2 · Ink jet printing apparatus and printing method

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- Number: US 8,770,693 B2
- Document ID: US8770693B2
- Status: Granted
- Kind: B2
- Application number: 13/188,591
- Filed: 2011-07-22
- Published: 2012-02-02
- Granted: 2014-07-08
- Earliest claimed: 2010-07-30
- Assignees: Canon Kabushiki Kaisha
- Applicants: Hirokazu Tanaka; Tetsuya Edamura; Toshiyuki Chikuma; Takatoshi Nakano; Wakako Yamamoto; Kiichiro Takahashi
- Inventors: Hirokazu Tanaka; Tetsuya Edamura; Toshiyuki Chikuma; Takatoshi Nakano; Wakako Yamamoto; Kiichiro Takahashi
- Web page: https://patentgrep.com/patent/US8770693B2

## CPC

- 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)}
- B41J 2/2125: {by means of nozzle diameter selection}
- G06K 15/107: {Mask selection}
- B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- G06K: GRAPHICAL DATA READING (image or video recognition or understanding G06V); PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS

## Abstract

An ink jet printing apparatus and printing method are provided that can, without the addition of a special structure, suppress density imbalance between the print images formed by ink ejected from each of the ejection ports formed on a print head. As for the plurality of ejection ports, one portion of them are established as multiple impact ejection ports that form multiply impacted pixels at which the number of times ink is impacted at the same area is greater than at other pixels of the print area. And, print control is carried out such that more multiply impacted pixels are printed at print areas printed using ejection ports at the ends of the print head than at print areas printed without using ejection ports at the ends of the print head.

## Claims

### Claim 1

An ink jet printing method for printing an image on a print medium by ejecting ink from a print head, on which a plurality of ejection ports are aligned, based on print permitting ratios which indicate whether or not ejection of ink is permitted, comprising the steps of:
printing a first part of the image with a plurality of scans of the print head to a first area on the print medium by using ejection ports located at ends of the print head in at least one scan; and
printing a second part of the image with a plurality of scans of the print head to a second area on the print medium without using ejection ports located at the ends of the print head,
wherein a sum of the print permitting ratios in the plurality of scans to the first area is larger than a sum of the print permitting ratios in the plurality of scans to the second area.

### Claim 2 (depends on 1)

The ink jet printing method according to claim 1, wherein the number of scans to the first area is larger than the number of scans to the second area.

### Claim 3 (depends on 1)

The ink jet printing method according to claim 1, wherein based on first mask patterns corresponding to print permitting ratios to the first area in the plurality of scans, data for printing in each of the plurality of scans to the first area is generated, and wherein based on second mask patterns corresponding to print permitting ratios to the second area in the plurality of scans, data for printing in each of the plurality of scans to the second area is generated.

### Claim 4 (depends on 3)

The ink jet printing method according to claim 3, wherein the print permitting ratios corresponding to the first area are respective duty in each of the first mask patterns, and wherein the print permitting ratios corresponding to the second area are respective duty in each of the second mask patterns.

### Claim 5 (depends on 4)

The ink jet printing method according to claim 4, wherein the sum of respective duty in each of the first mask patterns is larger than 100%, and wherein the sum of respective duty in each of the second mask patterns is 100%.

### Claim 6 (depends on 1)

The ink jet printing method according to claim 1, wherein the number of scans to the first area is the same as the number of scans to the second area.

### Claim 7 (depends on 1)

The ink jet printing method according to claim 1, wherein the number of scans to the first area is three, and the number of scans to the second area is two.

### Claim 8

An ink jet printing method for printing an image on a print medium by ejecting ink from a print head having a first ejection port array and a second ejection port array that ejects ink of the same color as the first ejection port array, the ejection port arrays being aligned in a scanning direction, based on print permitting ratios which indicate whether or not ejection of ink is permitted, comprising the steps of:
printing a first part of the image to a first area on the print medium with the print head by using ejection ports located at ends of the first and second ejection port arrays in at least one scan; and
printing a second part of the image to a second area on the print medium with the print head without using ejection ports located at the ends of the first and second ejection port arrays,
wherein a sum of the print permitting ratios to the first area is larger than a sum of the print permitting ratios to the second area.

### Claim 9 (depends on 8)

The ink jet printing method according to claim 8, wherein the image is printed to the first and second areas by one scan of the print head.

### Claim 10 (depends on 8)

The ink jet printing method according to claim 8, wherein the print permitting ratio corresponding to the first area is larger than 100%, and wherein the print permitting ratio corresponding to the second area is 100%.