DOT formation position misalignment adjustment performed using pixel-level information indicating dot non-formation

• US 6,547,355 B1
• Filed: 11/09/2000
• Issued: 04/15/2003
• Est. Priority Date: 03/10/1999
• Status: Expired due to Term

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Kanaya, Munehide, Hayashi, Toshihiro, Otsuki, Koichi, Shimada, Kazumichi
• Primary Examiner(s): Nguyen, Judy
• Assistant Examiner(s): MOUTTET, BLAISE L
• Application Number:
  US09/708,620
• Time in Patent Office: 887 Days
• Field of Search: 347/9, 347/16, 347/19, 347/104, 347/37, 347/39, 347/12, 347/14, 347/40, 347/41, 358/1.5, 358/1.8, 358/1.9, 358/1.12, 358/1.14, 358/502, 358/504, 358/406, 400/76, 400/279
• US Class Current: 347/12
• CPC Class Codes: B41J 19/145 Dot misalignment correction
• 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: B41J 2/2135 Alignment of dots

Abstract

While performing main scanning in which a head having a plurality of nozzles that eject ink is moved in prescribed forward and reverse main scanning directions relative to a print medium, print images are printed on the print medium by forming dots in each pixel aligned in the main scanning direction in accordance with print data. The dot formation position misalignment amount for each nozzle is corrected using image pixel value data indicating the existence of image pixels comprising images and adjustment pixel value data indicating the existence of adjustment pixels in which dots are not formed.

Claims

1. A printing apparatus comprising:

a head having a plurality of nozzles that eject ink;

a main scanning unit that carries out main scanning by moving the head forward and backward in prescribed directions relative to a print medium;

a head driving unit that drives the head in at least one of the forward and reverse passes in accordance with print data and forms dots on at least some of a plurality of pixels aligned in the main scanning direction;

a sub-scanning unit that carries out sub-scanning by moving the print medium forward relative to the head in a sub-scanning direction that is perpendicular to the main scanning direction; and

a control unit that controls printing,

wherein the print data includes raster data having;

image pixel value data indicating a dot formation status at image pixels that constitute images, and being two-dimensional image data indicating the pixels aligned in the two dimensions of the main scanning direction and the sub-scanning direction;

adjustment pixel value data indicating existence of adjustment pixels in which dots are not formed and which are used to adjust positions of the image pixels in the main scanning direction and are located in at least one end of the image pixel value data, with regard to each nozzle for each main scanning session,

wherein the control unit includes;

an image pixel value data memory unit that stores the image pixel value data;

a misalignment amount memory unit that stores an amount of the dot formation position misalignment;

a determining unit that determines the relationship of correspondence between each nozzle mounted in the head and the two-dimensional image data in accordance with an amount of sub-scan feed;

an allocation setting unit that allocates the adjustment pixels to one or both ends of the image pixel value data based on the determination so that the misalignment amount is corrected;

a raster data generating unit that generates the raster data from the image pixel value data and the allocation of the adjustment pixels, and

corrects, in dot formation in accordance with the print data, dot formation position misalignment in the main scanning direction for each nozzle, using the image pixel value data and the adjustment pixel value data.

2. The printing apparatus according to claim 1, wherein

the head forms dots of various colors by ejecting ink of prescribed colors from each nozzle;

the misalignment amount memory unit stores the formation position misalignment amount for each ink color; and

the allocation setting unit sets the allocation separately for each ink color.

3. The printing apparatus according to claim 1, wherein the plurality of nozzles are classified into a plurality of nozzle rows that extend in the sub-scanning direction and that are aligned in the main scanning direction;

the misalignment amount memory unit stores the formation position misalignment amount for each nozzle row; and

the allocation setting unit sets the allocation separately for each nozzle row.

4. The printing apparatus according to claim 1, wherein

the misalignment amount memory unit stores the formation position misalignment amount separately for each nozzle;

and

the allocation setting unit sets the allocation separately for each nozzle.

5. The printing apparatus according to claim 1, wherein the head driving unit drives the head along both the forward and reverse scanning passes of main scanning.

6. The printing apparatus according to claim 1, wherein the head driving unit drives the head only along either the forward or the reverse scanning pass.

7. The printing apparatus according to claim 1, wherein the head driving unit completes dot recording for each main scanning line during one pass of the head.

8. The printing apparatus according to claim 1, wherein the printing apparatus further comprises:

a test pattern data memory unit that stores test pattern data used to print prescribed test patterns designed to enable detection of the amount of dot formation position misalignment for each nozzle; and

a misalignment amount setting unit that sets the misalignment amount to be stored in the misalignment amount memory unit based on the test patterns printed using the test pattern data.

9. The printing apparatus according to claim 1, wherein

the head driving unit drives the head along both the forward and reverse scanning passes;

the print data includes;

raster data block having at least the image pixel value data with regard to each nozzle for each main scanning session,

sub-scan feed data that indicates a feed amount for sub-scanning performed after main scanning session, and

adjustment pixel placement data, that is separate from the raster data block, indicating numbers of adjustment pixels to be placed at opposite ends of the image pixel value data, the adjustment pixel placement data functioning as at least a part of the adjustment pixel value data; and

the control unit includes

a pass reversal detecting unit that detects that a direction of a scheduled pass for each raster data block is reversed, and

a raster data reconstruction unit that reconstructs the raster data block by reversing placement of the adjustment pixels across the image pixels sandwiched between the adjustment pixels, for the raster data block regarding which the pass is reversed, and by aligning, based on the reversed placement of the adjustment pixels, the adjustment pixel value data in at least one of the opposite ends of the image pixel value data.

10. The printing apparatus according to claim 9, wherein the raster data prior to the reconstruction further includes, as at least a part of the adjustment pixel value data, adjustment pixel data having the same format as the image pixel value data.

11. The printing apparatus according to claim 9, wherein each raster data block also includes a direction flag indicating the direction of the scheduled pass for each raster data block.

12. The printing apparatus according to claim 9, wherein

the head forms dots of various colors through ejection of ink of a prescribed color from each nozzle;

and

the adjustment pixel placement number in the adjustment pixel placement data is determined separately for each ink color.

13. The printing apparatus according to claim 9, wherein

the plurality of nozzles are classified into a plurality of nozzle rows that extend in the sub-scanning direction and that are aligned in the main scanning direction;

and

the adjustment pixel placement number in the adjustment pixel placement data is determined separate for each nozzle row.

14. The printing apparatus according to claim 9, wherein the adjustment pixel placement number in the adjustment pixel placement data is determined separately for each nozzle.

15. The printing apparatus according to claim 1, wherein

the head has a driving device for each nozzle to eject ink;

the head driving unit has a drive signal generating unit that generates drive signals to drive the driving devices to eject ink;

the drive signal generating unit has a base drive signal generating unit that generates base drive signals that are used to generate the drive signals, the base drive signals repeatedly generating a signal for the nozzle to record one pixel;

the base drive signal generating unit generates a plurality of base drive signals that have the same periods but different phases that are mutually offset from each other; and

the raster data generating unit has a pass splitting unit that classifies the image pixels and the adjustment pixels aligned in each main scanning line into a plurality of pixel groups, and

the dots on respective pixels in the plurality of pixel groups are formed based on the different base drive signals respectively.

16. The printing apparatus according to claim 15, wherein

the plurality of base drive signals includes N base drive signals having phases that are sequentially offset by an amount equal to 1/N of one period (N being a natural number equal or greater than 2);

and

the number of the pixel groups is N.

17. The printing apparatus according to claim 16, wherein the pass splitting unit classifies every Nth pixel of the image pixels and the adjustment pixels aligned in a main scanning line into the same pixel group in the order of their placement.

18. The printing apparatus according to claim 16, wherein the head driving unit drives the head along both the forward and reverse scanning passes of main scanning.

19. The printing apparatus according to claim 16, wherein the head driving unit drives the head only along either the forward or the reverse scanning pass.

20. The printing apparatus according to claim 2, wherein

the plurality of nozzles are classified into a plurality of nozzle rows that extend in the sub-scanning direction and that are aligned in the main scanning direction with a prescribed interval therebetween;

and wherein

the printing apparatus includes;

a delay data memory unit that stores delay data indicating an amount of delay needed to correct for a difference in times that nozzles arrive at a particular pixel during main scanning, in accordance with a design distance between the nozzle rows aligned in the main scanning direction with the prescribed interval therebetween;

a misalignment amount memory unit that stores the dot formation position misalignment amount; and

a delay data adjustment unit that readjusts the delay data so that the misalignment is corrected; and

wherein

the control unit includes a serial data generating unit that, for each nozzle during each main scanning session, generates serial data using the readjusted delay data as the adjustment pixel value data, and supplies this serial data to the head driving unit, the serial data includes the readjusted delay data and the image pixel value data that follows the readjusted delay data.

21. The printing apparatus according to claim 20, wherein

the head has a driving device for each nozzle to eject ink;

the head driving unit has a drive signal generating unit that generates drive signals to drive the driving devices to eject ink;

the drive signal generating unit has a base drive signal generating unit that generates base drive signals that are used to generate the drive signals, the base drive signals repeatedly generating a signal for the nozzle to record one pixel;

the delay data memory unit stores the delay data that is expressed in units of one period of the base drive signals;

the delay data adjustment unit readjusts the delay data in units of one period of the base drive signals based on the misalignment amount; and

the drive signal generating unit generates the drive signals from the serial data for each nozzle and the base drive signals.

22. The printing apparatus according to claim 21, wherein the nozzle rows aligned in the main scanning direction are aligned with an interval therebetween equal to a multiple m (m being a natural number equal to or greater than 1) of a pixel pitch corresponding to the print resolution.

23. The printing apparatus according to claim 21, wherein the head driving unit drives the head along both the forward and reverse scanning passes of main scanning.

24. The printing apparatus according to claim 21, wherein the head driving unit drives the head only along either the forward or the reverse scanning pass.

25. The printing apparatus according to claim 2, wherein

the plurality of nozzles are classified into N nozzle groups (N being a natural number equal to or greater than 2);

the base drive signal generating unit generates N base drive signals that have the same periods but different phases that are sequentially offset by an amount equal to 1/N of one period, and supplies the base drive signals to the driving devices of the corresponding nozzle groups; and

the drive signal generating unit generates drive signals from the serial data for each nozzle and the base drive signals supplied to the driving devices for each nozzle.

26. The printing apparatus according to claim 25, wherein the nozzle rows aligned in the main scanning direction are aligned with an interval therebetween equal to a multiple (N×

m) (m being a natural number equal to or greater than

     1) of a pixel pitch corresponding to the print resolution.

27. A printing control apparatus that generates print data to be supplied to a printing unit, the printing unit performing main scanning in which a head having a plurality of nozzles that eject ink is moving forward and backward in prescribed directions relative to a print medium, carrying out sub-scanning in which the print medium is forwarded in a sub-scanning direction perpendicular to the main scanning direction relative to the head, and driving the head in accordance with the print data along at least one of the forward or reverse scanning passes such that dots are formed on at least some of a plurality of pixels aligned along the main scanning direction,

wherein the printing control apparatus generates the print data, in which dot formation position misalignment for each nozzle in the main scanning direction is corrected,

wherein the print data includes raster data having:

image pixel value data indicating a dot formation status at image pixels that constitute images and being two-dimensional image data indicating the pixels aligned in the two dimensions of the main scanning direction and the sub-scanning direction;

adjustment pixel value data indicating existence of adjustment pixels in which dots are not formed and which are used to adjust positions of the image pixels in the main scanning direction, and being located at least one end of the image pixel value data, with regard to each nozzle for each main scanning session, wherein the printing control apparatus further comprises;

an image pixel value data memory unit that stores the image pixel value data;

a misalignment amount memory unit that stores an amount of the dot formation position misalignment;

a determining unit that determines the relationship of correspondence between each nozzle mounted in the head and the two-dimensional image data in accordance with an amount of sub-scan feed;

an allocation setting unit that allocates the adjustment pixels to one or both ends of the image pixel value data based on the determination so that the dot formation position misalignment amount is corrected; and

a raster data generating unit that generates the raster data from the image pixel value data and the allocation of the adjustment pixels.

28. The printing control apparatus according to claim 27, wherein

the head of the printing unit forms dots of various colors by ejecting ink of prescribed colors from each nozzle;

the misalignment amount memory unit stores the formation position misalignment amount separately for each ink color; and

the allocation setting unit sets the allocation separately for each ink color.

29. The printing control apparatus according to claim 27, wherein

the plurality of nozzles belonging to the printing unit are classified into a plurality of nozzle rows that extend in the sub-scanning direction and that are aligned in the main scanning direction;

the misalignment amount memory unit stores the formation position misalignment amount for each nozzle row; and

the allocation setting unit sets the allocation separately for each nozzle row.

30. The printing control apparatus according to claim 27, wherein

the misalignment amount memory unit stores the formation position misalignment amount for each nozzle;

and

the allocation setting unit sets the allocation separately for each nozzle.

31. The printing control apparatus according to claim 27, wherein the printing unit drives the head along both the forward and reverse scanning passes;

the print data includes;

raster data block having at least the image pixel value data with regard to each nozzle for each main scanning session,

sub-scan feed data that indicates a feed amount for sub-scanning performed after main scanning session,

adjustment pixel placement data, that is separate from the raster data block, indicating numbers of adjustment pixels to be placed at opposite ends of the image pixel value data, the adjustment pixel placement data functioning as at least a part of the adjustment pixel value data; and

the printing control apparatus includes

a pass reversal detecting unit that detects that a direction of a scheduled pass for each raster data block is reversed, and

a raster data reconstruction unit that reconstructs the raster data block by reversing placement of the adjustment pixels across the image pixels sandwiched between the adjustment pixels, for the raster data block regarding which the pass is reversed, and by aligning, based on the reversed placement of the adjustment pixels, the adjustment pixel value data at least one of the opposite ends of the image pixel value data.

32. The printing control apparatus according to claim 31, wherein the raster data prior to the reconstruction further includes, as at least a part of the adjustment pixel value data, adjustment pixel data having the same format as the image pixel value data.

33. The printing control apparatus according to claim 31, wherein each raster data block also includes a direction flag indicating the direction of the scheduled pass for each raster data block.

34. The printing control apparatus according to claim 27, wherein

the printing unit (i) has a driving device for each nozzle to eject ink, (ii) generates a plurality of base drive signals in which signals or a nozzle to record one pixel are repeated, and (iii) generates from the base drive signals drive signals to drive the driving devices to eject ink, the plurality of base drive signals being a plurality of base drive signals that have the same periods but different phases that are mutually offset from each other;

and

the raster data generating unit has a pass splitting unit that classifies the image pixels and the adjustment pixels aligned in each main scanning line into a plurality of pixel groups; and

the dots on respective pixels in the plurality of pixel groups are formed based on the different base drive signals respectively.

35. The printing control apparatus according to claim 34, wherein

the plurality of base drive signals includes N base drive signals having phases that are sequentially offset by an amount equal to 1/N of one period (N being a natural number equal to or greater than 2);

and

the number of the pixel groups is N.

36. The printing control apparatus according to claim 35, wherein the pass splitting unit classifies every Nth pixel of the image pixels and the adjustment pixels aligned in a main scanning line into the same pixel group in the order of their placement.

37. The printing control unit according to claim 27, wherein

the plurality of nozzles belonging to the printing unit are classified into a plurality of nozzle rows that extend in the sub-scanning direction and that are aligned in the main scanning direction with a prescribed interval therebetween;

and wherein

the printing control apparatus has

a delay data memory unit that stores delay data indicating an amount of delay needed to correct for a difference in times that nozzles arrive at a particular pixel during main scanning, in accordance with a design distance between the nozzle rows aligned in the main scanning direction with the prescribed interval therebetween;

a misalignment amount memory unit that stores the dot formation position misalignment amount; and

a delay data adjustment unit that readjusts the delay data so that the misalignment is corrected; and

a serial data generating unit that, for each nozzle during each main scanning session, generates serial data using the readjusted delay data as the adjustment pixel value data, and supplies this serial data to the head driving unit, the serial data includes the readjusted delay data and the image pixel value data that follows the readjusted delay data.

38. A printing method comprising the steps of:

while performing main scanning in which a head having a plurality of nozzles that eject ink is moved in prescribed forward and reverse directions relative to a print medium, carrying out sub-scanning in which the print medium is forwarded in a sub-scanning direction perpendicular to the main scanning direction relative to the head;

driving the head in accordance with print data along at least one of the forward or reverse scanning passes to form dots in at least some of the plurality of pixels aligned in the main scanning direction,

wherein the printing method corrects the dot formation position misalignment for each nozzle in the main scanning direction using image pixel value data as well as adjustment pixel value data, the image pixel value data indicating a dot formation status regarding image pixels that constitute images, and comprising two-dimensional image data indicating pixels aligned in the two dimensions of the main scanning direction and the sub-scanning direction, the adjustment pixel value data indicating existence of adjustment pixels in which dots are not formed and are used to adjust positions of the image pixels in the main scanning direction, and

further comprises the steps of;

setting the allocation of the adjustment pixels to one or both ends of the image pixel value data so that the amount of the dot formation position misalignment is corrected;

generating, from the image pixel value data and the allocation of the adjustment pixels, raster data having the image pixel value data and the adjustment pixel value data placed at least one side of the image pixel value data;

generating the print data including the raster data,

wherein the step of setting the allocation of the adjustment pixels comprises the steps of;

determining the relationship of correspondence between each nozzle mounted in the head and the two-dimensional image data in accordance with an amount of sub-scan feed; and

setting the allocation of the adjustment pixels based on the determination.

39. The printing method according to claim 38, wherein

the step of driving the head includes a step of forming dots of various colors by ejecting ink of a prescribed color from each nozzle; and

the step of setting the allocation includes a step of setting the allocation separately for each ink color.

40. The printing method according to claim 38, wherein

the step of driving the head includes a step of forming dots using a plurality of nozzles that are classified into a plurality of nozzle rows that extend in the sub-scanning direction and that are aligned in the main scanning direction;

and

the step of setting the allocation includes a step of setting the allocation separately for each nozzle row.

41. The printing method according to claim 38, wherein

the step of driving the head includes a step of setting the allocation separately for each nozzle.

42. The printing method according to claim 38, wherein the step of setting the allocation includes a step of driving the head along both the forward and reverse passes of main scanning.

43. The printing method according to claim 38, wherein the step of setting the allocation includes a step of driving the head either the forward or reverse scanning passes.

44. The printing method according to claim 38, wherein the step of setting the allocation includes a step of completing dot recording for each main scanning line during one pass of the head.

45. The printing method according to claim 38, wherein the method further comprising the steps of:

printing prescribed test patterns designed to enable detection of the amount of dot formation position misalignment for each nozzle; and

specifying the misalignment amount based on the test patterns.

46. The printing method according to claim 38, wherein

the step of detecting includes a step of classifying the image pixels and the adjustment pixels aligned in each main scanning line into a plurality of pixel groups;

and wherein

the step of reconstructing further comprising the steps of;

generating a plurality of base drive signals in which signals for the nozzles to record one pixel are repeated;

generating from the base drive signals drive signals to drive the driving devices mounted in each nozzle to eject ink; and

forming dots on respective pixels in the plurality of pixel groups based on the different base drive signals respectively; and

wherein

the plurality of base drive signals having same periods but different phases that are mutually offset from each other.

47. The printing method according to claim 46, wherein

the plurality of base drive signals includes N base drive signals having phases that are sequentially offset by an amount equal to 1/N of one period (N being a natural number equal to greater than 2);

and

the number of the pixel groups is N.

48. The printing method according to claim 47, wherein the step of detecting includes a step of classifying every Nth pixel of the image pixels and the adjustment pixels aligned in a main scanning line into the same pixel group in the order of their placement.

49. A printing method comprising the steps of:

while performing main scanning in which a head having a plurality of nozzles that eject ink is moved in prescribed forward and reverse directions relative to a print medium, carrying out sub-scanning in which the print medium is forwarded in a sub-scanning direction perpendicular to the main scanning direction relative to the head;

driving the head in accordance with print data along at least one of the forward or reverse scanning passes; and

forming dots in at least some of the plurality of pixels aligned in the main scanning direction,

wherein the printing method corrects the dot formation position misalignment for each nozzle in the main scanning direction using image pixel value data as well as adjustment pixel value data, the image pixel value data indicating a dot formation status regarding image pixels that constitute images, and comprising two-dimensional image data indicating pixels aligned in the two dimensions of the main scanning direction and the sub-scanning direction, the adjustment pixel value data indicating existence of adjustment pixels in which dots are not formed and are used to adjust positions of the image pixels in the main scanning direction, and

further comprises the steps of;

generating the print data that includes

raster data block that has at least the image pixel value data with regard to each nozzle for each main scanning session;

sub-scan feed data that indicates a feed amount for the sub-scanning performed after each main scanning session; and

adjustment pixel placement data, that is separate from the raster data block, indicating numbers of adjustment pixels to be placed at opposite ends of the image pixel value data, the adjustment pixel placement data functioning as at least a part of the adjustment pixel value data;

driving the head and forming dots in both the forward and reverse scanning passes in accordance with the print data;

detecting that a direction of a scheduled pass for each raster data block is reversed; and

reconstructing the raster data block by reversing placement of the adjustment pixels across the image pixels sandwiched between the adjustment pixels, for the raster data block regarding which the pass is reversed, and by aligning, based on the reversed placement of the adjustment pixels, the adjustment pixel value data at least one of the opposite ends of the image pixel value data,

wherein the step of generating the print data includes the step of;

setting the allocation of the adjustment pixels to one or both ends of the image pixel value data so that the amount of the dot formation position misalignment is corrected,

wherein the step of setting the allocation of the adjustment pixels includes the steps of;

determining the relationship of correspondence between each nozzle mounted in the head and the two-dimensional image data in accordance with an amount of sub-scan feed; and

setting the allocation of the adjustment pixels based on the determination.

50. The printing method according to claim 49, wherein the step of generating the print data includes a step of generating adjustment pixel data having the same format as the image pixel data as at least a part of the adjustment pixel value data.

51. The printing method according to claim 49, wherein the step of generating the print data includes a step of placing a directional flag indicating the direction of the scheduled scanning pass for each raster data block.

52. The printing method according to claim 49, wherein

the step of driving the head includes a step of forming dots of various colors through ejection of ink of a prescribed color from each nozzle; and

the step of generating the print data includes a step of setting the adjustment pixel placement number in the adjustment pixel placement data separately for each ink color.

53. The printing method according to claim 49, wherein

the step of generating the print data includes a step of forming dots using a plurality of nozzles that are classified into a plurality of nozzle rows that extend in the sub-scanning direction and that are aligned in the main scanning direction;

and

the step of driving the head includes a step of setting the adjustment pixel placement number in the adjustment pixel placement data separately for each nozzle row.

54. The printing method according to claim 49, wherein the step of driving the head includes a step of setting the adjustment pixel placement number in the adjustment pixel placement data separately for each nozzle.

55. A printing method comprising the steps of:

while performing main scanning in which a head having a plurality of nozzles that eject ink is moved in prescribed forward and reverse directions relative to a print medium, carrying out sub-scanning in which the print medium is forwarded in a sub-scanning direction perpendicular to the main scanning direction relative to the head;

driving the head in accordance with print data along at least one of the forward or reverse scanning passes; and

forming dots in at least some of the plurality of pixels aligned in the main scanning direction,

wherein the printing method corrects the dot formation position misalignment for each nozzle in the main scanning direction using image pixel value data as well as adjustment pixel value data, the image pixel value data indicating a dot formation status regarding image pixels that constitute images, and comprising two-dimensional image data indicating pixels aligned in the two dimensions of the main scanning direction and the sub-scanning direction, the adjustment pixel value data indicating existence of adjustment pixels in which dots are not formed and are used to adjust positions of the image pixels in the main scanning direction, and

further comprising the steps of;

readjusting the delay data indicating an amount of delay needed to correct for a difference in times that nozzles arrive at a particular pixel during main scanning, in accordance with a design distance in the main scanning direction between the plurality of nozzles classified into a plurality of nozzle rows that extend in the sub-scanning direction and that are aligned in the main scanning direction with a prescribed interval therebetween, so that the dot formation position misalignment amount may be corrected;

generating serial data that includes the readjusted delay data and the image pixel value data that follows the readjusted delay data, for each nozzle during each main scanning session, using the readjusted delay data as the adjustment pixel value data; and

forming dots based on the serial data,

wherein the step of generating serial data includes the step of;

setting the allocation of the adjustment pixels to one or both ends of the image pixel value data so that the amount of the dot formation position misalignment is corrected,

wherein the step of setting the allocation of the adjustment pixels includes the steps of;

determining the relationship of correspondence between each nozzle mounted in the head and the two-dimensional image data in accordance with an amount of sub-scan feed; and

setting the allocation of the adjustment pixels based on the determination.

56. The printing method according to claim 55, wherein the step of forming dots includes

generating a plurality of base drive signals in which signals for the nozzles to record one pixel are repeated; and

generating from the base drive signals drive signals to drive the driving devices mounted in each nozzle to eject ink; and

wherein

the delay data is prepared in units of one period of the base drive signals;

the step of readjusting includes a step of readjusting the delay data in units of one period of the base drive signals based on the misalignment amount; and

the step of generating from the base drive signals drive signals includes a step of generating the drive signals from the serial data and the base drive signals for each nozzle.

57. The printing method according to claim 56, wherein

the plurality of nozzles are classified into N nozzle groups (N being a natural number equal to or greater than 2);

the step of generating a plurality of base drive signals includes steps of generating N base drive signals that have same periods but different phases that are sequentially offset by an amount equal to 1/N of one period, and supplying the base drive signals to the driving devices of the nozzle group corresponding to each of the base drive signals; and

the step of generating from the base drive signals drive signals includes a step of generating the drive signals from the serial data for each nozzle and the base drive signals supplied to the driving device for each nozzle.

58. The printing method according to claim 57, wherein the nozzle rows aligned in the main scanning direction have an interval therebetween equal to the multiple (N×

m) (m being a natural number equal to or greater than

     1)of a pixel pitch corresponding to the print resolution.

59. The printing method according to claim 56, wherein the step of forming dots further comprising the step of:

driving the head along both the forward and reverse scanning passes of main scanning.

60. The printing method according to claim 56, wherein the step of forming dots further comprising the step of:

driving the head only along either the forward or the reverse scanning pass.

61. A recording medium on which is recorded a computer program to execute printing from a computer having a printing apparatus that, while performing main scanning in which a head having a plurality of nozzles that eject ink is moved in prescribed forward and reverse directions relative to a print medium, carries out sub-scanning in which the print medium is forwarded in a sub-scanning direction perpendicular to the main scanning direction relative to the head, drives the head in accordance with print data along at least one of the forward or reverse scanning passes in accordance with the print data, and forms dots in at least some of the a plurality of pixels aligned in the main scanning direction, wherein

recorded on the recording medium is a computer program to achieve the function of correcting the dot formation position misalignment for each nozzle in the main scanning direction using image pixel value data as well as adjustment pixel value data, the image pixel value data indicating a dot formation status regarding image pixels that constitute images, and comprising two-dimensional image data indicating pixels aligned in the two dimensions of the main scanning direction and the sub-scanning direction, the adjustment pixel value data indicating existence of adjustment pixels in which dots are not formed and are used to adjust positions of the image pixels in the main scanning direction,

wherein recorded on the recording medium is a computer program to achieve:

a function to set the allocation of the adjustment pixels to one or both ends of the image pixel value data so that the dot formation position misalignment amount is corrected;

a function to generate, from the image pixel value data and the allocation of the adjustment pixels, raster data having the image pixel value data and the adjustment pixel value data placed at least one side of the image pixel value data;

a function to generate the print data including the raster data; and

a function to drive the head in accordance with the print data while performing main scanning,

wherein recorded on the recording medium is the computer program to achieve in setting the allocation of the adjustment pixels;

a function to determine the relationship of correspondence between each nozzle mounted in the head and the two-dimensional image data in accordance with an amount of sub-scan feed; and

a function to set the allocation of the adjustment pixels based on the determination.

62. The printing method according to claim 61, wherein the method achieves

a function to classify the image pixels and the adjustment pixels aligned in each main scanning line into a plurality of pixel groups when the raster data is generated; and

when the head is driven and dots are formed,

a function to generate a plurality of base drive signals in which signals for the nozzles to record one pixel are repeated;

a function to generate from the base drive signals drive signals to drive the driving devices mounted in each nozzle to eject ink; and

a function to form dots on respective pixels in the plurality of pixel groups based on the different base drive signals respectively; and

wherein

the plurality of base drive signals have same periods but different phases that are mutually offset from each other.

63. A recording medium on which is recorded a computer program to execute printing from a computer having a printing apparatus that, while performing main scanning in which a head having a plurality of nozzles that eject ink is moved in prescribed forward and reverse directions relative to a print medium, carries out sub-scanning in which the print medium is forwarded in a sub-scanning direction perpendicular to the main scanning direction relative to the head, drives the head in accordance with print data along at least one of the forward or reverse scanning passes in accordance with the print data, and forms dots in at least some of the plurality of pixels aligned in the main scanning direction, wherein

recorded on the recording medium is a computer program to achieve the function of correcting the dot formation position misalignment for each nozzle in the main scanning direction using image pixel value data as well as adjustment pixel value data, the image pixel value data indicating a dot formation status regarding image pixels that constitute images, and comprising two-dimensional image data indicating pixels aligned in the two dimensions of the main scanning direction and the sub-scanning direction, the adjustment pixel value data indicating existence of adjustment pixels in which dots are not formed and are used to adjust positions of the image pixels in the main scanning direction,

wherein recorded on the recording medium is a computer program to achieve

a function to generate the print data including:

raster data block that has at least image pixel value data with regard to each nozzle for each main scanning session;

sub-scan feed data that indicates a feed amount for the sub-scanning performed after each main scanning session; and

adjustment pixel placement data, that is separate from the raster data block, indicating numbers of adjustment pixels to be placed at opposite ends of the image pixel value data, the adjustment pixel placement data functioning as at least a part of the adjustment pixel value data;

a function to drive the head and form dots in both the forward and reverse scanning passes;

a function to detect that a direction of a scheduled pass for each raster data block is reversed; and

a function to reconstruct the raster data block by reversing placement of the adjustment pixels across the image pixels sandwiched between the adjustment pixels, for the raster data block regarding which the pass is reversed, and by aligning, based on the reversed placement of the adjustment pixels, the adjustment pixel value data at least one of the opposite ends of the image pixel value data,

wherein recorded on the recording medium is the computer program to achieve in generating the print data;

a function to set the allocation of the adjustment pixels to one or both ends of the image pixel value data so that the dot formation position misalignment amount is corrected,

wherein recorded on the recording medium is the computer program to achieve in setting the allocation of the adjustment pixels;

a function to determine the relationship of correspondence between each nozzle mounted in the head and the two-dimensional image data in accordance with an amount of sub-scan feed; and

a function to set the allocation of the adjustment pixels based on the determination.

64. A recording medium on which is recorded a computer program to execute printing from a computer having a printing apparatus that, while performing main scanning in which a head having a plurality of nozzles that eject ink is moved in prescribed forward and reverse directions relative to a print medium, carries out sub-scanning in which the print medium is forwarded in a sub-scanning direction perpendicular to the main scanning direction relative to the head, drives the head in accordance with print data along at least one of the forward or reverse scanning passes in accordance with the print data, and forms dots in at least some of the plurality of pixels aligned in the main scanning direction, wherein

recorded on the recording medium is a computer program to achieve the function of correcting the dot formation position misalignment for each nozzle in the main scanning direction using image pixel value data as well as adjustment pixel value data, the image pixel value data indicating a dot formation status regarding image pixels that constitute images, and comprising two-dimensional image data indicating pixels aligned in the two dimensions of the main scanning direction and the sub-scanning direction, the adjustment pixel value data indicating existence of adjustment pixels in which dots are not formed and are used to adjust positions of the image pixels in the main scanning direction,

wherein recorded on the recording medium is a computer program to achieve

a function to readjust the delay data indicating an amount of delay needed to correct for a difference in times that nozzles arrive at a particular pixel during main scanning, in accordance with the design distance in the main scanning direction between the plurality of nozzles classified into a plurality of nozzle rows that extend in the sub-scanning direction and that are aligned in the main scanning direction with a prescribed interval therebetween, so that the dot formation position misalignment amount may be corrected;

a function to generate serial data that includes the readjusted delay data and the image pixel value data that follows the readjusted delay data, for each nozzle during each main scanning session, using the readjusted delay data as the adjustment pixel value data and

a function to form dots based on the serial data,

wherein recorded on the recording medium is the computer program to achieve in generating the serial data;

a function to set the allocation of the adjustment pixels to one or both ends of the image pixel value data so that the dot formation position misalignment amount is corrected,

wherein recorded on the recording medium is the computer program to achieve in setting the allocation of the adjustment pixels;

a function to determine the relationship of correspondence between each nozzle mounted in the head and the two-dimensional image data in accordance with an amount of sub-scan feed; and

a function to set the allocation of the adjustment pixels based on the determination.