Printing method and printing apparatus

• US 6,364,446 B1
• Filed: 06/07/2000
• Issued: 04/02/2002
• Est. Priority Date: 06/07/1999
• Status: Expired due to Fees

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Tajika, Hiroshi, Edamura, Tetsuya, Ishikawa, Hisashi, Konno, Yuji, Kawatoko, Norihiro, Maeda, Tetsuhiro, Inoue, Hiroo
• Primary Examiner(s): NGUYEN, THINH H
• Application Number:
  US09/588,177
• Time in Patent Office: 664 Days
• Field of Search: 347/15, 347/16, 347/19, 358/461, 358/517
• US Class Current: 347/15
• CPC Class Codes: G06K 15/107 Mask selection
• CPC Class Codes: H04N 1/4015 of the reproducing head

Abstract

A printing method capable of printing a high-quality image at a high speed and low cost and a corresponding printing apparatus are disclosed. In this printing apparatus, a shading-corrected mask pattern for multipass printing control in consideration of the characteristics of each printing element of a printhead is generated. The size of the mask pattern in the conveyance direction of the printing medium is set to be an integer multiple of the conveyance amount of the printing medium per scanning of the printhead. Image data masked using the mask pattern is transferred to the printhead and printed. Alternatively, the conveyance-direction size of the mask pattern for masking print data in accordance with each pass printing of multipass printing is set to be equivalent to the number of nozzles of an ink-jet printhead having a plurality of nozzles arrayed in the conveyance direction of the printing medium, and the mask pattern is dividedly used for each pass printing. Any error of the position of a dot printed on the printing medium by an ink droplet discharged from each nozzle is detected in units of nozzles. Printing may be performed using a mask pattern generated such that a printing element with a small error is frequently used in accordance with the detection result, or performed such that the positions of print data are exchanged.

Claims

1. A printing method of printing data on a printing medium under multipass printing control of a printhead having a plurality of printing elements, comprising:

a generation step of generating a shading-corrected mask pattern for the multipass printing control in consideration of characteristics of each printing element of said printhead;

a setting step of setting a size of the mask pattern in a conveyance direction of the printing medium to be an integer multiple of a conveyance amount of the printing medium per scanning of said printhead; and

a printing step of applying the mask pattern to image data, transferring the masked image data to said printhead, and printing.

2. The method according to claim 1, wherein the image data is data obtained by binarizing multivalued density data.

3. The method according to claim 2, wherein said generation step generates a plurality of mask patterns in accordance with a density range of the multivalued density data.

4. The method according to claim 3, further comprising a selection step of selecting one of the plurality of mask patterns in accordance with the density range of the multivalued density data.

5. The method according to claim 1, wherein said generation step, in units of printing elements of said printhead, inputs density data, performs correction so that a relationship between the input density data and an output density obtained from said printhead by actual printing becomes linear, and generates the mask pattern on the basis of the correction.

6. A printing method of printing data on a printing medium under multipass printing control of a printhead having a plurality of printing elements, comprising:

a generation step of, in units of printing elements of said printhead, inputting data indicating a position of said printhead along a moving direction of said printhead and quantized data, and generating a conversion table used for outputting a shading-corrected dot pattern in consideration of characteristics of each printing element of said printhead;

a setting step of setting a size of the conversion table in a conveyance direction of the printing medium to be an integer multiple of a conveyance amount of the printing medium per scanning of said printhead; and

a printing step of inputting quantized data which has undergone pseudo-halftoning to the conversion table to convert the quantized data, transferring the converted quantized data to said printhead, and printing.

7. The method according to claim 6, wherein the pseudo-halftoning includes error diffusion processing.

8. The method according to claim 6, wherein said generation step, in units of printing elements of said printhead, inputs density data, performs correction so that a relationship between the input density data and an output density obtained from said printhead by actual printing becomes linear, and generates the conversion table on the basis of the correction.

9. A printing apparatus for printing data on a printing medium under multipass printing control of a printhead having a plurality of printing elements, comprising:

generation means for generating a shading-corrected mask pattern for the multipass printing control in consideration of characteristics of each printing element of said printhead;

setting means for setting a size of the mask pattern in a conveyance direction of the printing medium to be an integer multiple of a conveyance amount of the printing medium per scanning of said printhead; and

printing means for applying the mask pattern to image data, transferring the masked image data to said printhead, and printing.

10. The apparatus according to claim 9, wherein said printhead is an ink-jet printhead for discharging ink for printing.

11. The apparatus according to claim 10, wherein said ink-jet printhead comprises an electrothermal transducer for generating thermal energy to be given to ink to discharge the ink using the thermal energy.

12. A printing apparatus for printing data on a printing medium under multipass printing control of a printhead having a plurality of printing elements, comprising:

generation means for, in units of printing elements of said printhead, inputting data indicating a position of said printhead along a moving direction of said printhead and quantized data, and generating a conversion table used for outputting a shading-corrected dot pattern in consideration of characteristics of each printing element of said printhead;

setting means for setting a size of the conversion table in a conveyance direction of the printing medium to be an integer multiple of a conveyance amount of the printing medium in each scanning cycle of said printhead; and

printing means for inputting quantized data which has undergone pseudo-halftoning to the conversion table to convert the quantized data, transferring the converted quantized data to said printhead, and printing.

13. The apparatus according to claim 12, wherein said printhead is an ink-jet printhead for discharging ink for printing.

14. The apparatus according to claim 13, wherein said printhead comprises an electrothermal transducer for generating thermal energy to be given to ink to discharge the ink using the thermal energy.

15. A printing method of printing data on a printing medium by multipass printing while scanning, in a direction perpendicular to a conveyance direction of the printing medium, a printhead having a plurality of printing elements arrayed in the conveyance direction, comprising:

a setting step of setting a size of a mask pattern, in the conveyance direction, for masking print data in accordance with each pass printing of the multipass printing to be equivalent to the number of said plurality of printing elements arrayed on said printhead; and

a division step of dividing the mask pattern for each pass printing, and using the divided mask pattern.

16. The method according to claim 15, wherein said printhead is an ink-jet printhead, and further comprising a detection step of detecting, in units of said plurality of printing elements, an error of a position of a dot printed on the printing medium by an ink droplet discharged from said ink-jet printhead, and wherein

printing is performed using the mask pattern generated such that a printing element with a small error is frequently used in accordance with a detection result obtained in said detection step.

17. The method according to claim 16, wherein the mask pattern is formed using a lookup table format,

and further comprising an update step of updating contents of the lookup table in accordance with the detection result obtained in said detection step.

18. The method according to claim 16, wherein the error includes an error in the conveyance direction of the printing medium, an error in a scanning direction of said printhead, or errors in the conveyance direction of the printing medium and in the scanning direction of said printhead.

19. The method according to claim 16, further comprising an exchange step of exchanging positions of print data in accordance with the detection result obtained in said detection step.

20. The method according to claim 19, wherein the exchange step includes exchanging the position of the print data in the conveyance direction of the printing medium, exchanging the position of the print data in the scanning direction of said printhead, or exchanging the positions of the print data in the conveyance direction of the printing medium and in a scanning direction of said printhead.

21. The method according to claim 16, wherein said ink-jet printhead comprises an electrothermal transducer for generating thermal energy to be given to ink to discharge the ink using the thermal energy.

22. A printing apparatus comprising:

conveyance means for conveying a printing medium;

an ink-jet printhead having a plurality of printing elements arrayed in a conveyance direction of the printing medium;

scanning means for reciprocally scanning said ink-jet printhead;

a printing buffer for temporarily storing print data; and

control means for controlling to print the data on the printing medium on the basis of the print data stored in said printing buffer using said ink-jet printhead by multipass printing using a mask pattern for masking the print data in accordance with each pass printing,

wherein a size of the mask pattern in the conveyance direction is set to be equivalent to the number of said plurality of printing elements arrayed on said printhead, and the mask pattern is dividedly used for each pass printing.

23. The apparatus according to claim 22, further comprising detection means for detecting, in units of said plurality of printing elements, an error of a position of a dot printed on the printing medium by an ink droplet discharged from said ink-jet printhead, wherein

printing is performed using the mask pattern generated such that a printing element with a small error is frequently used in accordance with a detection result obtained by said detection means.

24. The apparatus according to claim 23, wherein the mask pattern is formed using a lookup table format,

and further comprising update means for updating contents of the lookup table in accordance with the detection result obtained by said detection means.

25. The apparatus according to claim 23, wherein the error includes an error in the conveyance direction of the printing medium, an error in a scanning direction of said printhead, or errors in the conveyance direction of the printing medium and in the scanning direction of said printhead.

26. The apparatus according to claim 23, further comprising exchange means for exchanging positions of print data in accordance with the detection result obtained by said detection means.

27. The apparatus according to claim 26, wherein the exchange includes exchanging the position of the print data in the conveyance direction of the printing medium, exchanging the position of the print data in the scanning direction of said printhead, or exchanging the positions of the print data in the conveyance direction of the printing medium and in the scanning direction of said printhead.

28. The apparatus according to claim 22, wherein said ink-jet printhead comprises an electrothermal transducer for generating thermal energy to be given to ink to discharge the ink using the thermal energy.

29. A printing method of printing an image on a printing medium by using a printhead having a plurality of printing elements, comprising the steps of:

inputting multi-valued density data corresponding to each of said plurality of printing elements;

quantizing the inputted multi-valued density data, based on a quantized level corresponding to each of said plurality of printing elements; and

printing by driving said plurality of printing elements, based on the quantized data,

wherein the quantized level is corrected, based on correction data corresponding to a printing characteristic of each of said plurality of printing elements.

30. The method according to claim 29, wherein the quantized level is stored in a look-up table.

31. The method according to claim 29, wherein the quantized data is corrected by shading data for correcting the printing characteristic of each of said plurality of printing elements.

32. The method according to claim 29, wherein said printhead is an ink-jet printhead for printing by discharging ink.

33. The method according to claim 32, wherein said ink-jet printhead comprises an electrothermal transducer for generating thermal energy to be given to ink to discharge the ink using the thermal energy.

34. An image processing apparatus for processing image data to be inputted into a printing apparatus for printing an image on a printing medium by using a printhead having a plurality of printing elements, comprising:

input means for inputting multi-valued density data corresponding to each of said plurality of printing elements;

a table for storing a quantization level corresponding to each of said plurality of printing elements;

correction means for correcting the quantization level stored in said table, based on shading data for correcting a printing characteristic of each of said plurality of printing elements; and

quantization means for quantizing the multi-valued density data inputted by said input means, based on the quantized level corrected by said correction means.

35. The apparatus according to claim 34, wherein said printhead is an ink-jet printhead for printing by discharging ink.

36. The apparatus according to claim 35, wherein said ink-jet printhead comprises an electrothermal transducer for generating thermal energy to be given to ink to discharge the ink using the thermal energy.