Printing apparatus, storage medium having a program recorded thereon, pattern, computer system, and printing method

• US 20030179256A1
• Filed: 02/21/2003
• Published: 09/25/2003
• Est. Priority Date: 02/21/2002
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Endo, Hironori
• Granted Patent: US 6,964,465 B2
• Time in Patent Office: Days
• US Class Current: 347/19
• CPC Class Codes: B41J 19/145 Dot misalignment correction
• CPC Class Codes: B41J 2/04505 aiming at correcting alignment
• CPC Class Codes: B41J 2/04581 controlling heads based on piezoelectric elements
• CPC Class Codes: B41J 2/04588 using a specific waveform
• CPC Class Codes: B41J 2/04593 Dot-size modulation by changing the size of the drop
• CPC Class Codes: B41J 29/393 Devices for controlling or analysing the entire machine ; Controlling or analysing mechanical parameters involving printing of test patterns

Abstract

A printing apparatus of the invention has an ejection head for ejecting ink droplets to form dots on a printing medium. The printing apparatus is capable of printing a correction pattern on the printing medium with the ejection head, the correction pattern having a plurality of sub-patterns for correcting a misalignment between a position at which dots are formed during a forward pass through which the head is moved and a position at which dots are formed during a return pass through which the head is moved, and correcting the misalignment based on two or more sub-patterns that stand out in density among the plurality of sub-patterns.

Claims

1. A printing apparatus comprising:

an ejection head for ejecting ink droplets to form dots on a printing medium;

wherein said printing apparatus is capable of

printing a correction pattern on said printing medium with said ejection head, said correction pattern having a plurality of sub-patterns for correcting a misalignment between a position at which dots are formed during a forward pass through which said head is moved and a position at which dots are formed during a return pass through which said head is moved, and

correcting said misalignment based on two or more sub-patterns that stand out in density among said plurality of sub-patterns.

2. A printing apparatus according to claim 1, wherein

each sub-pattern is made of dots arranged in a main-scanning direction and a sub-scanning direction.

3. A printing apparatus according to claim 1, wherein

each of said sub-patterns has forward-pass dots that are formed with a predetermined spacing therebetween during the forward pass through which said head is moved and return-pass dots that are formed with a predetermined spacing therebetween during the return pass through which said head is moved, and

an amount of misalignment between a position at which the forward-pass dots are formed and a position at which the return-pass dots are formed is different for each sub-pattern.

4. A printing apparatus according to claim 1, wherein

a correction amount with respect to said misalignment is set to be an integer multiple of a distance that is obtained by evenly dividing an ideal dot pitch in a main-scanning direction, and

a number of the sub-patterns included in the correction pattern is larger than a number by which the ideal dot pitch has been divided.

5. A printing apparatus according to claim 1, wherein

said sub-patterns are arranged in order of correction amounts corresponding to each said sub-pattern, and

said printing apparatus is capable of

selecting two of the sub-patterns based on a density distribution in the main-scanning direction of said correction pattern, and

regarding a median between the correction values of the two selected sub-patterns as a correction value for correcting said misalignment.

6. A printing apparatus according to claim 5, wherein

said two sub-patterns are

a sub-pattern that stands out the most in the density distribution in the main-scanning direction of said correction pattern and

a sub-pattern that is located away from this sub-pattern by said number by which the ideal dot pitch has been divided.

7. A printing apparatus according to claim 5, wherein

in said correction pattern, a predetermined sub-pattern and a sub-pattern located away therefrom by said number by which the ideal dot pitch has been divided are regarded as a sub-pattern pair, and

among the sub-pattern pairs, the sub-pattern pair that stands out the most in average density is regarded as said two sub-patterns.

8. A printing apparatus according to claim 7, wherein,

if there are a plurality of sub-pattern pairs that stand out the most in said average density, then each of the sub-patterns located in the middle of each of these sub-pattern pairs are regarded as said two sub-patterns.

9. A printing apparatus according to claim 7, wherein

if there are a plurality of sub-pattern pairs that stand out the most in said average density, then the sub-pattern pair that includes a sub-pattern having a density that stands out the most among the sub-patterns making up each of the sub-pattern pairs is regarded as said two sub-patterns.

10. A printing apparatus according to claim 5, wherein

the density distribution of said correction pattern is a curved line interpolated based on the density of each sub-pattern.

11. A printing apparatus according to claim 5, wherein

if two sub-patterns that stand out in the density distribution in the main-scanning direction of said correction pattern do not exist,

then

a correction amount of a sub-pattern that is located at an end in the main-scanning direction is changed and

a new correction pattern in which the correction amounts have sequentially been changed in the main-scanning direction is printed.

12. A printing apparatus according to claim 11, wherein

the correction amounts for printing the new correction pattern are changed according to a position of a sub-pattern that stands out in density with respect to a sub-pattern serving as a reference of said correction amount.

13. A printing apparatus according to claim 1, further comprising:

a sensor for scanning said printed correction pattern in the main-scanning direction and reading a density of each sub-pattern;

wherein

the density of said printed correction pattern is read by said sensor, and

said misalignment is corrected based on density information that has been read out.

14. A printing apparatus according to claim 13, further comprising:

selection means for selecting a sub-pattern that stands out in density based on said density information;

wherein

if two or more sub-patterns that stand out in density cannot be selected by said selection means, then

a correction amount of a sub-pattern that is located at an end in the main-scanning direction is changed and

a new correction pattern is printed.

15. A printing apparatus comprising:

an ejection head for ejecting ink droplets to form dots on a printing medium;

wherein

said printing apparatus is capable of printing a correction pattern on said printing medium with said ejection head, said correction pattern having a plurality of sub-patterns for correcting a misalignment between a position at which dots are formed during a forward pass through which said head is moved and a position at which dots are formed during a return pass through which said head is moved,

each of said sub-patterns is made of forward-pass dots and return-pass dots arranged in a main-scanning direction and a sub-scanning direction, said forward-pass dots being formed with a predetermined spacing therebetween during the forward pass through which said head is moved, and said return-pass dots being formed with a predetermined spacing therebetween during the return pass through which said head is moved,

an amount of misalignment between a position at which the forward-pass dots are formed and a position at which the return-pass dots are formed is different for each sub-pattern,

a correction amount with respect to said misalignment is set to be an integer multiple of a distance that is obtained by evenly dividing an ideal dot pitch in a main-scanning direction,

a number of the sub-patterns included in the correction pattern is larger than a number by which the ideal dot pitch has been divided,

said sub-patterns are arranged in order of correction amounts corresponding to each said sub-pattern, and

said printing apparatus is capable of

selecting two of the sub-patterns based on a density distribution in the main-scanning direction of said correction pattern,

regarding a median between the correction values of the two selected sub-patterns as a correction value for correcting said misalignment, and

if two sub-patterns that stand out in the density distribution in the main-scanning direction of said correction pattern do not exist, changing a correction amount of a sub-pattern that is located at an end in the main-scanning direction, and printing a new correction pattern in which the correction amounts have sequentially been changed in the main-scanning direction.

16. A storage medium having a program recorded thereon, comprising:

a memory for storing the program;

wherein

said program is capable of making a printing apparatus that has an ejection head for ejecting ink droplets to form dots on a printing medium;

print a correction pattern on said printing medium with said ejection head, said correction pattern having a plurality of sub-patterns for correcting a misalignment between a position at which dots are formed during a forward pass through which said head is moved and a position at which dots are formed during a return pass through which said head is moved, and

correct said misalignment based on two or more sub-patterns that stand out in density among said plurality of sub-patterns.

17. A storage medium according to claim 16, wherein

if two sub-patterns that stand out in the density distribution in the main-scanning direction of said correction pattern do not exist,

said program makes said printing apparatus

change a correction amount of a sub-pattern that is located at an end in the main-scanning direction and

print a new correction pattern in which the correction amounts have sequentially been changed in the main-scanning direction.

18. A storage medium according to claim 17, wherein

said program has a function making information for urging a change of the correction amount of said sub-pattern that is located at the end in the main-scanning direction be displayed by a user interface.

19. A correction pattern comprising:

a plurality of sub-patterns that are printed by a printing apparatus having an ejection head for ejecting ink droplets to form dots on a printing medium and that are for correcting a misalignment between a position at which dots are formed during a forward pass through which said head is moved and a position at which dots are formed during a return pass through which said head is moved;

wherein

said correction pattern has two or more sub-patterns that stand out in density among said plurality of sub-patterns.

20. A computer system comprising:

a computer main unit; and

a printing apparatus that has an ejection head for ejecting ink droplets to form dots on a printing medium, is connected to said computer main unit, and is capable of performing printing to the printing medium;

wherein said computer system is capable of

printing a correction pattern on said printing medium with said ejection head, said correction pattern having a plurality of sub-patterns for correcting a misalignment between a position at which dots are formed during a forward pass through which said head is moved and a position at which dots are formed during a return pass through which said head is moved, and

correcting said misalignment based on two or more sub-patterns that stand out in density among said plurality of sub-patterns.

21. A printing apparatus comprising:

an ejection head for selectively ejecting ink droplets of a plurality of sizes to form dots on a printing medium;

wherein

said printing apparatus is capable of printing a correction pattern on said printing medium, said correction pattern enabling correction of a misalignment between a position at which dots are formed during a forward pass through which said head is moved and a position at which dots are formed during a return pass through which said head is moved, and

a spacing in a sub-scanning direction between dots that make up said correction pattern printed by ejecting ink droplets of a certain size from said ejection head is different from a spacing in the sub-scanning direction between dots that make up said correction pattern printed by ejecting ink droplets of a different size from said ejection head.

22. A printing apparatus according to claim 21, wherein

said correction pattern has a plurality of sub-patterns, and

each sub-pattern is made of dots arranged in a main-scanning direction and the sub-scanning direction.

23. A printing apparatus according to claim 22, wherein

each said sub-pattern has forward-pass dots that are formed with a predetermined spacing therebetween during the forward pass through which said head is moved and return-pass dots that are formed with a predetermined spacing therebetween during the return pass through which said head is moved, and

an amount of misalignment between a position at which the forward-pass dots are formed and a position at which the return-pass dots are formed is different for each sub-pattern.

24. A printing apparatus according to claim 21, wherein

a spacing in a main-scanning direction between the dots forming said correction pattern is the same regardless of said size.

25. A printing apparatus according to claim 23, wherein

said predetermined spacing is at least twice the spacing in the sub-scanning direction between the dots.

26. A printing apparatus according to claim 23, further comprising:

a density detection member for detecting a density of said sub-patterns;

wherein

the misalignment between a position at which dots are formed during a forward pass through which said head is moved and a position at which dots are formed during a return pass through which said head is moved is corrected based on a result of the density detected by said density detection member.

27. A printing apparatus comprising:

an ejection head for selectively ejecting ink droplets of a plurality of sizes to form dots on a printing medium;

wherein

said printing apparatus is capable of printing a correction pattern on said printing medium, said correction pattern enabling correction of a misalignment between a position at which dots are formed during a forward pass through which said head is moved and a position at which dots are formed during a return pass through which said head is moved,

a spacing in a sub-scanning direction between dots that make up said correction pattern printed by ejecting ink droplets of a certain size from said ejection head is different from a spacing in the sub-scanning direction between dots that make up said correction pattern printed by ejecting ink droplets of a different size from said ejection head, and

said printing apparatus is capable of

receiving command information from a user based on said correction pattern, and,

based on the command information, correcting a misalignment between a position at which dots are formed during a forward pass through which said head is moved and a position at which dots are formed during a return pass through which said head is moved.

28. A printing apparatus comprising:

an ejection head for selectively ejecting ink droplets of a plurality of sizes to form dots on a printing medium;

wherein

said printing apparatus is capable of printing a correction pattern on said printing medium, said correction pattern enabling correction of a misalignment between a position at which dots are formed during a forward pass through which said head is moved and a position at which dots are formed during a return pass through which said head is moved,

a spacing in a sub-scanning direction between dots that make up said correction pattern printed by ejecting ink droplets of a certain size from said ejection head is different from a spacing in the sub-scanning direction between dots that make up said correction pattern printed by ejecting ink droplets of a different size from said ejection head,

said correction pattern has a plurality of sub-patterns,

each sub-pattern is made of dots arranged in a main-scanning direction and the sub-scanning direction,

each said sub-pattern has forward-pass dots that are formed with a predetermined spacing therebetween during the forward pass through which said head is moved and return-pass dots that are formed with a predetermined spacing therebetween during the return pass through which said head is moved,

an amount of misalignment between the forward-pass dots and the return-pass dots is different for each sub-pattern,

a spacing in the main-scanning direction between the dots forming said correction pattern is the same regardless of said size,

said predetermined spacing is at least twice the spacing in the sub-scanning direction between the dots,

said printing apparatus further comprises a density detection member for detecting a density of said sub-patterns, and

the misalignment between a position at which dots are formed during a forward pass through which said head is moved and a position at which dots are formed during a return pass through which said head is moved is corrected based on a result of the density detected by said density detection member.

29. A correction pattern comprising:

forward-pass dots that are formed by an ejection head during a forward pass through which said head is moved, said ejection head being capable of selectively ejecting ink droplets of a plurality of sizes to form dots on a printing medium; and

return-pass dots that are formed by said ejection head during a return pass through which said head is moved;

wherein

said correction pattern is for correcting a misalignment between a position at which the forward-pass dots are formed and a position at which the return-pass dots are formed, and

a spacing in a sub-scanning direction between dots that make up said correction pattern printed by ejecting ink droplets of a certain size from said ejection head is different from a spacing in the sub-scanning direction between dots that make up said correction pattern printed by ejecting ink droplets of a different size from said ejection head.

30. A computer system comprising:

a computer main unit; and

a printing apparatus that has an ejection head for selectively ejecting ink droplets of a plurality of sizes to form dots on a printing medium, is connected to said computer main unit, and is capable of performing printing to the printing medium; and

wherein

said computer system is capable of printing a correction pattern on said printing medium, said correction pattern enabling correction of a misalignment between a position at which dots are formed during a forward pass through which said head is moved and a position at which dots are formed during a return pass through which said head is moved, and

a spacing in a sub-scanning direction between dots that make up said correction pattern printed by ejecting ink droplets of a certain size from said ejection head is different from a spacing in the sub-scanning direction between dots that make up said correction pattern printed by ejecting ink droplets of a different size from said ejection head.

31. A printing apparatus comprising:

a carry roller for carrying a print sheet;

wherein

said carry roller has virtual circumference segments that are obtained by virtually dividing a circumference of the carry roller into a plurality of segments in a direction in which the carry roller is rotated, and

said printing apparatus is capable of

printing a plurality of patterns for each of said virtual circumference segments, each of said patterns corresponding to a different correction amount, and

setting a correction amount corresponding to one of the patterns to each said virtual circumference segment.

32. A printing apparatus according to claim 31, wherein

said printing apparatus is capable of forming the pattern for determining a correction amount for a predetermined virtual circumference segment by printing a predetermined structural pattern before and after the print sheet is carried by that virtual circumference segment of said carry roller.

33. A printing apparatus according to claim 31, wherein

the patterns, which correspond to the correction amounts for each of the virtual circumference segments, are arranged in a row in a carry direction of the print sheet for each of the virtual circumference segments, and

the pattern rows, which are arranged in rows, are printed on a single print sheet in a direction that is perpendicular to said carry direction.

34. A printing apparatus according to claim 32, wherein

the plurality of patterns for each of said virtual circumference segments corresponding to one correction amount are formed starting from a front end side of the print sheet in order of formation of the patterns.

35. A printing apparatus according to claim 31, wherein said printing apparatus is capable of

forming a pattern group by forming patterns for each of said virtual circumference segments corresponding to one correction amount, and

changing said correction amount each time said carry roller makes a full turn and forming said pattern group made of patterns corresponding to the correction amount that has been changed.

36. A printing apparatus according to claim 35, further comprising

a print head for printing while performing scanning in a direction that is perpendicular to a carry direction of said print sheet;

wherein

as for two adjacent patterns that make up one of said pattern groups, a structural pattern printed before carrying in one pattern and a structural pattern printed after carrying in another pattern are printed during the same scan of the print head.

37. A printing apparatus according to claim 36, wherein

said print head has a plurality of nozzles that are arranged in the carry direction of said print sheet and that are capable of ejecting ink,

said patterns are formed using some of said nozzles, and

nozzles forming the structural pattern printed after said carrying by a particular virtual circumference segment are located more toward the front end of the print sheet than nozzles forming the structural pattern printed before said carrying.

38. A printing apparatus according to claim 31, wherein

a length of each said pattern in said carry direction is shorter than a product of an amount the print sheet is carried and a number into which said carry roller is virtually divided.

39. A printing apparatus according to claim 32, wherein

said structural pattern is made of a plurality of lines spaced at an equal spacing in a carry direction of the print sheet, or dot rows arranged in a direction that is perpendicular to said carry direction, and

a correction amount corresponding to the pattern in which said lines or said dot rows of the structural pattern that is printed after carrying are formed at a position that evenly divides a space between said lines or said dot rows of the structural pattern that is printed before carrying said print sheet is set.

40. A printing apparatus according to claim 32, wherein

said structural pattern is made of a plurality of lines spaced at an equal spacing in a carry direction of the print sheet, or dot rows arranged in a direction that is perpendicular to said carry direction, and

a correction amount corresponding to the pattern in which said lines or said dot rows of the structural pattern that is printed after carrying are formed at a position that overlaps said lines or said dot rows of the structural pattern that is printed before carrying said print sheet is set.

41. A printing apparatus comprising:

a carry roller for carrying a print sheet;

wherein

said carry roller has virtual circumference segments that are obtained by virtually dividing a circumference of the carry roller into a plurality of segments in a direction in which the carry roller is rotated,

said printing apparatus is capable of

printing a plurality of patterns for each of said virtual circumference segments, each of said patterns corresponding to a different correction amount,

setting a correction amount corresponding to one of the patterns to each said virtual circumference segment,

printing a predetermined structural pattern before and after the print sheet is carried by a predetermined virtual circumference segment of said carry roller, and

forming a pattern for determining a correction amount for that virtual circumference segment,

the patterns, which correspond to the correction amounts for each of the virtual circumference segments, are arranged in a row in a carry direction of the print sheet for each of the virtual circumference segments,

the pattern rows, which are arranged in rows, are printed on a single print sheet arranged in a direction that is perpendicular to said carry direction,

the plurality of patterns for each of said virtual circumference segments corresponding to one correction amount are formed starting from a front end side of the print sheet in order of formation of the patterns,

said printing apparatus is capable of

forming a pattern group by forming patterns for each of said virtual circumference segments corresponding to one correction amount, and

changing said correction amount each time said carry roller makes a full turn and forming said pattern group made of patterns corresponding to the correction amount that has been changed,

said printing apparatus further comprises a print head for printing while performing scanning in a direction that is perpendicular to a carry direction of said print sheet,

as for two adjacent patterns that make up one of said pattern groups, a structural pattern printed before carrying in one pattern and a structural pattern printed after carrying in another pattern are printed during the same scan of the print head,

said print head has a plurality of nozzles that are arranged in the carry direction of said print sheet and that are capable of ejecting ink,

said patterns are formed using some of said nozzles,

nozzles forming the structural pattern printed after said carrying by a particular virtual circumference segment are located more toward the front end of the print sheet than nozzles forming the structural pattern printed before said carrying,

a length of each said pattern in said carry direction is shorter than a product of an amount the print sheet is carried and a number into which said carry roller is virtually divided,

said structural pattern is made of a plurality of lines spaced at an equal spacing in a carry direction of the print sheet, or dot rows arranged in a direction that is perpendicular to said carry direction, and

a correction amount corresponding to the pattern in which said lines or said dot rows of the structural pattern that is printed after carrying are formed at a position that evenly divides a space between said lines or said dot rows of the structural pattern that is printed before carrying said print sheet is set.

42. A carry amount correction pattern comprising:

a plurality of pattern, each said pattern corresponding to a different correction amount;

wherein

the carry amount correction pattern has said plurality of patterns for each virtual circumference segment obtained by virtually dividing a circumference of a carry roller for carrying a print sheet into a plurality of segments in a direction in which the carry roller is rotated.

43. A storage medium having a program recorded thereon, comprising:

a memory for storing the program;

wherein said program is capable of making a printing apparatus that has a carry roller for carrying a print sheet;

print a plurality of patterns for each of a plurality of virtual circumference segments, each of said patterns corresponding to a different correction amount, and each of said virtual circumference segments being obtained by virtually dividing a circumference of said carry roller into a plurality of segments in a direction in which the carry roller is rotated, and

set a correction amount corresponding to one of the patterns to each said virtual circumference segment.

44. A computer system comprising:

a computer main unit; and

a printing apparatus that has a carry roller for carrying a print sheet and that is capable of being connected to said computer main unit;

wherein

said carry roller has virtual circumference segments that are obtained by virtually dividing a circumference of the carry roller into a plurality of segments in a direction in which the carry roller is rotated, and

said printing apparatus is capable of

printing a plurality of patterns for each of said virtual circumference segments, each of said patterns corresponding to a different correction amount, and

setting a correction amount corresponding to one of the patterns to each said virtual circumference segment.

45. A printing method comprising:

printing a plurality of patterns for each of a plurality of virtual circumference segments, each of said patterns corresponding to a different correction amount, and each of said virtual circumference segments being obtained by virtually dividing a circumference of a carry roller into a plurality of segments in a direction in which the carry roller is rotated, and

setting a correction amount corresponding to one of the patterns to each said virtual circumference segment.