JP2011005808A - Printer, printing method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deviation in printing between a preceding nozzle train and a following nozzle train when printing by arranging a plurality of nozzle trains at different positions in a recording medium conveying direction.SOLUTION: The printer includes a plurality of nozzle trains 2-11 to 2-14 and 2-21 to 2-24 ejecting recording material of a different kind at different positions in a relative conveying direction to a printing medium 1, wherein the plurality of nozzle trains 2-11 to 2-14 and 2-21 to 2-24 include a plurality of nozzles arranged along in a direction crossing the conveying direction. The printer includes a means (9) configured to acquire density of the recording material with which the printing medium is to be printed for every recording material of the different kind, a means (9) configured to acquire the kind of the printing medium, and a means (10) configured to adjust angles of each of the plurality of nozzle trains in a nozzle arranging direction and the conveying direction from printing information including the density of the recording material with which the printing medium is to be printed and the kind of the printing medium.

Description

  The present invention relates to a printing apparatus, a printing method, and a program.

  A line-type printing apparatus is used as an inkjet printing apparatus capable of high-speed printing. In a line-type printing apparatus, one or a plurality of print heads that realize a nozzle array having a length corresponding to the length in the width direction of the recording medium (direction perpendicular to the transport direction) are used. The recording medium is conveyed, and printing on the recording medium is performed without moving the print head in the direction orthogonal to the conveying direction. In such a line-type printing apparatus, in order to obtain a resolution higher than the pitch (nozzle interval) of the nozzle rows, a plurality of nozzle rows are arranged at different positions in the conveyance direction of the recording medium by shifting the nozzle positions. .

  When arranging a plurality of nozzle rows in this way, positional deviation between the nozzle rows may be a problem. Patent Document 1 discloses that the angle of the line head with respect to the paper transport direction is adjusted in order to prevent printing defects such as oblique lines due to poor alignment of the line head (nozzle row).

JP 2008-12712 A

  When printing with a plurality of nozzle rows arranged at different positions in the conveyance direction of the recording medium, in general paper, when the preceding nozzle row passes through the recording medium, the recording medium is caused by ink that has been driven into the recording medium. Will expand. Some recording media contract. Depending on the printing apparatus, a drying mechanism is provided, and the recording medium once expanded or contracted may contract or expand due to drying of the ink. When the succeeding nozzle row passes in such a state where the recording medium is expanded or contracted, a deviation occurs between the image printed by the preceding nozzle row and the image printed by the succeeding nozzle row. . As a result, problems such as ruled line multiplexing occur.

  It takes some time for the recording medium to absorb ink and expand or contract. For this reason, if the time interval for the nozzle row to pass through the recording medium is sufficiently short, printing can be performed with the succeeding nozzle row before the recording medium expands or contracts by absorbing ink from the preceding nozzle row. And there is almost no image shift. In order to shorten the time interval through which the nozzle row passes, it is conceivable to shorten the spatial interval of the nozzle row or shorten the transport time. However, shortening the spatial interval between the nozzle rows is actually limited because there are a mechanism for supplying ink and various other mechanisms. Further, the transport speed is also related to the ink discharge time and has a limit.

  The present invention solves such a problem, and when printing by arranging a plurality of nozzle rows at different positions in the conveyance direction of the recording medium, printing deviation between the preceding nozzle row and the following nozzle row is prevented. It is an object of the present invention to provide a printing apparatus, a printing method, and a program that can be prevented.

  According to the first aspect of the present invention, it has a plurality of nozzle rows that discharge different types of recording materials at different positions in the transport direction relative to the print medium, and each of the plurality of nozzle rows has a transport direction. A printing apparatus having a plurality of nozzles arranged in a direction intersecting with the print medium, a means for acquiring the density to be printed on the print medium for each different type of recording material, and a means for acquiring the type of the print medium And a means for adjusting the angle between the nozzle arrangement direction and the transport direction for each of the plurality of nozzle rows from the print information including the density to be printed and the type of print medium. Is provided.

  By adjusting the angle between the nozzle arrangement direction and the conveyance direction, the dot pitch of the recording material ejected from the nozzles can be adjusted. By performing this adjustment based on print information including the density to be printed and the type of print medium, even if the print medium expands and contracts, the respective print resolutions by the plurality of nozzle arrays become substantially equal. Therefore, it is possible to prevent printing deviation between nozzle rows. Here, the term “expansion and contraction” is used not only to expand or contract, but also to include contraction after expansion, expansion after contraction, and repetition of expansion and contraction.

  The means for adjusting the nozzle row for discharging the recording material to the printing medium prior to the other nozzle rows among the plurality of nozzle rows, considering the density of the recording material to be printed after that, It is desirable to adjust the angle between the nozzle arrangement direction of the nozzle row and the transport direction. That is, the angle is adjusted in consideration of not only expansion / contraction due to the recording material of each nozzle row but also expansion / contraction due to the recording material of the nozzle row to be printed later. As a result, it is possible to prevent printing deviation with higher accuracy.

  The means for adjusting the nozzle array for discharging the recording material preceding the nozzle array for discharging the recording material with the highest density among the different types of recording materials among the plurality of nozzle arrays and the nozzle arrangement direction and conveyance It is desirable to make the angle with the direction coincide with the angle between the nozzle array direction of the nozzle row that discharges the recording material with the highest density and the transport direction. Even if the amount of ink printed by a certain nozzle row is small, if a large amount of ink is ejected from the nozzle row immediately after, the expansion and contraction of the print medium will increase. In such a case, the printing deviation can be prevented by adjusting the angle of the preceding nozzle row to the angle of the immediately following nozzle row.

  According to the second aspect of the present invention, a plurality of nozzle rows that eject different types of recording materials are disposed at different positions in the transport direction relative to the print medium, and the transport directions from the plurality of nozzle rows respectively. Is a printing method in which recording material is ejected by a plurality of nozzles arranged along the direction intersecting with, acquiring the density to be printed on the printing medium for each different type of recording material, and obtaining the type of printing medium Then, a printing method is provided that adjusts the angle between the nozzle arrangement direction and the transport direction for each of a plurality of nozzle rows from printing information including the density to be printed and the type of printing medium. .

  According to a third aspect of the present invention, there is provided a program for controlling a printing apparatus connected to a computer by being installed in the computer, the printing apparatus being different at different positions in the conveyance direction relative to the printing medium. Each of the plurality of nozzle arrays has a plurality of nozzles arranged along a direction intersecting the transport direction, and each of the different types of recording materials The nozzle for each of a plurality of nozzle rows from the means for acquiring the density to be printed on the print medium, the means for acquiring the type of the print medium, and the print information including the density to be printed and the type of the print medium A program is provided that operates the computer as means for adjusting the angle between the arrangement direction and the transport direction.

FIG. 2 is a diagram illustrating the principle of the present invention, and is a block configuration diagram of a printing apparatus capable of adjusting an angle between a nozzle arrangement direction of a nozzle row and a conveyance direction. It is a figure explaining the example of nozzle arrangement | positioning of the print head of the printing apparatus shown in FIG. FIG. 10 is a diagram for describing correction of image shift between nozzle rows in a case where expansion and contraction of a print medium occurs on both sides with a center line as a reference. 1 is a block configuration diagram of a printing apparatus according to a first embodiment of the present invention. It is a block block diagram of the printing apparatus which concerns on the 2nd Embodiment of this invention. It is a figure explaining an example of arrangement | positioning of the nozzle row of the printing apparatus shown in FIG. It is a figure explaining the example different from FIG. 6 of arrangement | positioning of the nozzle row of the printing apparatus shown in FIG.

[Description of Principle]
Before describing the embodiment of the present invention, the basic concept of preventing printing deviation between the preceding nozzle row and the following nozzle row will be described.
[Constitution]
FIG. 1 is a diagram illustrating the principle of the present invention, and is a block diagram of a printing apparatus that can adjust the angle between the nozzle arrangement direction of a nozzle row and the transport direction. Here, in order to simplify the description, a case of monochrome printing will be described as an example.

  The printing apparatus shown in FIG. 1 includes print heads 2-1 and 2-2 having one nozzle row at different positions along the conveyance direction of the print medium 1. In the following description, it is assumed that the positions of the print heads 2-1 and 2-2 are fixed and the print medium 1 is conveyed to these print heads 2-1 and 2-2. The movements of the heads 2-1 and 2-2 are relative, and the print heads 2-1 and 2-2 may move, or both may move. Hereinafter, the direction in which the print medium 1 is conveyed is referred to as a medium conveyance direction. In the print head 2-1, one row of nozzles 21-1 to 21-10 (see FIG. 2) that discharges a recording material (ink) to the print medium 1 is arranged along a direction that intersects the medium conveyance direction. . Similarly, one row of nozzles 22-1 to 22-10 is arranged in the print head 2-2.

  The printing apparatus also includes a print control unit 3. The print control unit 3 includes an image input unit 4, an image conversion unit 5, a halftone processing unit 6, a nozzle drive unit 7, a conveyance control unit 8, an expansion rate estimation unit 9, and a head angle adjustment unit 10.

  The image input unit 4 captures image data from one or more of image data sources such as a computer, a network, and a recording medium. The image conversion unit 5 converts the captured image data into a printable format. In FIG. 1, monochromatic printing is described as an example. However, in a practical embodiment, the image conversion unit 5 converts image data input in RGB (red, green, blue) format or other formats into CMYK. (Cyan, magenta, yellow, black) and the like are converted into print data. The halftone processing unit 6 generates density data for each ink from the printing data obtained by the image conversion unit 5. The nozzle drive unit 7 controls the nozzles 21-1 to 21-10 and 22-1 to 22-10 in the print heads 2-1 and 2-2 according to the grayscale data obtained by the halftone processing unit 6. Drive to discharge the recording material.

  The expansion coefficient estimation unit 9 constitutes means for estimating the expansion coefficient, acquires information affecting the expansion / contraction of the print medium 1 from the print information to be printed on the print medium 1, and expands the expansion coefficient of the print medium 1. Is estimated. As the print information, the output of the halftone processing unit 6, medium information that is information on the print medium, and ink information that represents the type of ink are used.

  From the output of the halftone processing unit 6, the ink color to be ejected onto the print medium 1 and the average density of the image to be printed on the print medium 1, that is, the ink shot amount, are obtained. From the medium information, information on the type of the print medium 1, for example, the quality of the print medium 1, the basis weight (medium weight), the fiber direction, and the like are obtained. Furthermore, depending on the medium information, information on the drying conditions of the print medium 1, information on the time interval during which the nozzle arrays 2-1 and 2-2 pass through the print medium 1, and information on the movement of the print medium 1 may be obtained. it can.

  As the ink information, the type of ink to be used, the viscosity of the ink, and the like can be used. This ink information may be available automatically when the ink cassette is loaded, or may be detected by a separate sensor. In addition, the ink information may be manually input. The medium information is obtained by being input on an input screen that stands up before printing. Further, information obtained by various sensors such as a weight sensor installed in the printing apparatus can be used as the medium information.

  The expansion rate estimation unit 9 can also obtain a recording mode in which the image data is image-based or text-based as information relating to the amount of ink together with the medium information. The expansion coefficient estimation unit 9 estimates the expansion coefficient of the print medium 1 from any one or more of all the print information.

  As medium information input to the expansion coefficient estimation unit 9, a test pattern is printed on a medium substantially the same quality as the print medium 1 before actual printing is started, and after passing through each of the nozzle arrays 2-1, 2-2. Information obtained by measuring the expansion coefficient of the medium can also be included. Thereby, the actual expansion rate can be known using the same printing medium 1 used for actual printing, and the angle of the nozzle row can be adjusted more accurately.

  The head angle adjustment unit 10 constitutes a means for adjustment, and based on the expansion coefficient of the recording medium 1 estimated by the expansion coefficient estimation unit 9, the nozzle arrangement direction and medium conveyance direction of at least one of the nozzle arrays 21 and 22. And adjust the angle. In the example shown in FIG. 1, the angle of the nozzle row 21 is adjusted.

[Arrangement of nozzle rows]
FIG. 2 is a diagram illustrating an example of nozzle arrangement of the print heads 2-1 and 2-2 of the printing apparatus illustrated in FIG. Here, the nozzle row 21 is constituted by a plurality of nozzles 21-1 to 21-10 arranged in one row, and the nozzle row 22 is similarly a plurality of nozzles 22-1 to 22- arranged in one row. The example comprised by 10 is shown. Here, in order to simplify the explanation, the number of nozzles of each of the print heads 2-1 and 2-2 is nine, but the actual number of nozzles is the width of the print medium 1 (for example, 210 mm for A4), It is designed for printing resolution (for example, 360 dpi with one print head). The print heads 2-1 and 2-2 will be described as using the same product with the same nozzle interval. In addition, as an example of the print medium 11, a general paper that expands when ink is attached will be described.

  The nozzle rows 21 and 22 are arranged by shifting the positions of the nozzles 21-1 to 21-10 and the nozzles 22-1 to 22-10 in a direction parallel to the medium conveyance direction in order to obtain a resolution higher than the nozzle interval. The If the nozzle rows 21 and 22 are both aligned in the direction perpendicular to the medium transport direction, the print medium 1 will expand due to the ink that has been driven by the preceding nozzle row 21. For this reason, when an image is printed by the nozzle row 22 that follows from the top, a deviation occurs from the image printed by the nozzle row 21, thereby causing problems such as multiplexing of ruled lines.

  Therefore, as shown in FIG. 2, the angle between the arrangement direction of the nozzles 21-10 to 21-10 of the preceding nozzle row 21 and the medium conveyance direction is adjusted. As a result, the nozzle interval β of the nozzle row 21 in the direction orthogonal to the passing direction of the print medium 1 (referred to as “width direction”) is smaller than the interval α of the nozzle row 22. At this time, the dot interval printed by the nozzle row 21 is made equal to the nozzle interval α of the nozzle row 22 due to the expansion of the print medium 1. Thereby, it is possible to correct an image shift due to expansion of the print medium 1 in the width direction.

[Rotation of nozzle row]
When the conveyance of the print medium 1 is performed in a state where the print medium 1 is arranged in the center with respect to the center line of the print medium 1, the expansion and contraction of the print medium 1 occurs on both sides with respect to the center line. In this case, in order to adjust the angles of the nozzle rows 21 and 22, the print heads 2-1 and 2-2 are bi-directional based on the point where the nozzle arrangement direction intersects the center line of the print medium 1. The one that can be rotated is used. Thereby, the positions of the ink dots ejected from the nozzles 21-1 to 21-10 can be adjusted according to the estimated expansion and contraction of the print medium 1.

  FIG. 3 is a diagram for explaining correction of image misalignment between the nozzle arrays 21 and 22 when expansion and contraction of the print medium 1 occurs on both sides with respect to the center line. Here, for the sake of simplicity of explanation, the nozzle 21-5 of the preceding print head 2-1 and the nozzle 22-5 of the subsequent print head 2-2 are connected to the center line of the print medium 1 in the medium transport direction. It shall be arranged on the same line that matches. In FIG. 3, the nozzle 21-5 is the center of rotation of the print head 2-1, and the nozzle 22-5 is the center of rotation of the print head 2-2. Here, with reference to the direction in which the nozzle arrangement directions of the print heads 2-1 and 2-2 are orthogonal to the medium conveyance direction, the rotation angles of the nozzle arrays 21 and 22 from this direction are θ1 and θ2. In the example shown in FIG. 3, the rotation angle θ1 is greater than 0 degree and less than 90 degrees. The rotation angle θ2 is 0 degree.

  In the example illustrated in FIG. 3, the print medium 1 expands around a line connecting the nozzles 21-5 and 22-5. Then, the position shift increases as it goes to both sides of the print medium 1 in the width direction. On the other hand, by making the rotation angle θ1 of the nozzle row 21 larger than the rotation angle θ2 of the nozzle row 22, the difference in the nozzle position in the width direction between the nozzle row 21 and the nozzle row 22 is changed from the nozzles 21-5 and 22-5. It gets bigger as you leave. Here, the difference between the positions of the nozzle 21-4 and the nozzle 22-4 is γ1, the difference between the positions of the nozzle 21-3 and the nozzle 22-3 is γ2, and the difference between the positions of the nozzle 21-2 and the nozzle 22-2 is γ3. , ... At this time, the difference between the positions of the nozzles 21-6 and 22-6 is γ1, the difference between the positions of the nozzles 21-7 and 22-7 is γ2, and the difference between the positions of the nozzles 21-8 and 22-8 is γ3. , ... Further, γ2 = 2 × γ1, γ3 = 3 × γ1, and so on. That is, similarly to the positional deviation due to the printing medium 1, the nozzle positional deviation in the width direction can be increased as the printing medium 1 moves to both sides in the width direction. Therefore, by setting the rotation angle θ1 of the nozzle row 21 to be larger than the rotation angle θ2 of the nozzle row 22, the nozzle interval β of the preceding print head 2-1 is made wider than the nozzle interval α of the subsequent print head 2-2. The width of the print medium 1 can correspond to the expansion in the direction.

  Further, when the printing medium 1 is transported in a state where the printing medium 1 is justified, the nozzle rows 21 and 22 are rotated in both directions based on the points intersecting with the lines that serve as the basis for the justification. It is better to use what is possible.

  The print image of the nozzle row 21 is inclined by adjusting the angle of the nozzle row 21. This is because the ink discharge timings of the nozzles 21-1 to 21-10 of the nozzle row 21 are electrically controlled. It can be corrected by changing. Similarly, the correction of the deviation caused by the expansion of the print medium 1 in the medium conveyance direction can be electrically corrected.

[Expansion rate of print media]
Factors affecting the expansion rate of the print medium 1 mainly include the type and amount of ink (image density) and the type of the print medium 1. In particular, the ink having a high water content causes the printing medium 1 to swell, and if the ink amount increases, the printing medium 1 swells accordingly. Also, the expansion rate of the print medium 1 is greatly different between normal copy paper and coated paper even if the same type of ink is used in the same amount. Moreover, even if the paper has the same quality, the expansion rate differs if the basis weight is different.

  In a simple experiment by the inventors, when water-based ink was printed at a density of 3.6 mg / inch2 on A4 (width 210 mm, length 297 mm) coated paper having a basis weight of 104.7 g / m2, the center of the paper was fixed. In 4 seconds, there was an expansion of about 40 μm on one side in the lateral direction. That is, a total expansion of 80 μm occurred in the lateral direction. The longitudinal expansion was about 15 μm on one side in 4 seconds. The difference in expansion coefficient between the horizontal direction and the vertical direction is related to the direction of the paper, that is, the fiber. 4 seconds corresponds to the passage interval of the nozzle rows 21 and 22 in the actual printing apparatus. The expansion increased almost linearly up to about 20 seconds, after which the expansion was saturated. Subsequent expansion has not been measured, but is expected to shrink gradually as the ink dries. The actual expansion rate depends not only on the paper type but also on the manufacturer and product lot. In addition, depending on the type of ink, for example, oil-based ink or quick-drying or ultraviolet-curing ink may shrink instead of expanding within 4 seconds corresponding to the passage interval of the nozzle rows 21 and 22. Conceivable. In addition, it is also known that the nozzle rows 21 and 22 are subjected to a drying process. In this case, the print medium 1 may contract. Taking these into account, the angles of the nozzle rows 21 and 22 are adjusted.

Here, for simplicity, it is assumed that the width of the print medium 1 expands by 80 μm to 210 mm. At this time, an angle θ3 formed by the nozzle arrangement direction of the nozzle row 21 and the medium conveyance direction is
210 · sin θ3 = 210−80 × 10 ⁻³
By doing so, it is possible to cope with the expansion of the print medium 1. That is,
sin θ3 = 209.92 / 210
Should be set. When this is expressed by the rotation angle θ1 of the nozzle row 21, θ3 = π / 2−θ1.
cos θ1 = 209.92 / 210
It becomes.

  In the above description, the case where the print medium 1 expands during the passage interval between the nozzle arrays 21 and 22 has been mainly described. However, when the print medium 1 contracts, the nozzle array 2-1 is moved in the medium conveyance direction. The nozzle row 2-2 is adjusted so as to be inclined with respect to the medium conveyance direction. Both the nozzle arrays 21 and 22 may be inclined with respect to the medium conveyance direction, and the angle thereof may be adjusted.

  Here, the case where two nozzle rows 21 and 22 are arranged for the same color of ink has been described as an example, but the number of nozzle rows can be 3 or more, usually a power of 2. For example, when a resolution of 360 dpi (dots / inch) is obtained with one nozzle row, a resolution of 720 dpi with two nozzle rows and a resolution of 1440 dpi with four nozzle rows.

[Embodiment of the Invention]
In the foregoing, the basic concept of preventing printing deviation between the preceding nozzle row and the succeeding nozzle row has been described. Next, embodiments of the present invention will be described.

(Claim 1)
[First Embodiment]
FIG. 4 is a block diagram showing a modification of the printing apparatus according to the first embodiment of the present invention. This example is for performing multicolor printing, and instead of the print head 2-1 having the nozzle row 21 of the printing apparatus shown in FIG. 1, the print heads 2-11 to 11 having one nozzle row each. 2, and instead of the print head 2-2 having the nozzle row 22, print heads 2-21 to 2-24 each having one nozzle row are provided.

(Claim 1)
That is, the printing apparatus illustrated in FIG. 4 includes a plurality of print heads 2-11 to 2-14 and 2-21 to 2− that eject different types of ink at different positions in the conveyance direction relative to the print medium 1. 24. The print heads 2-11 and 2-21 eject the same ink, for example, cyan C. The print heads 2-12 and 2-22 eject the same ink, for example, magenta M, different from the print heads 2-11 and 2-21. The print heads 2-13 and 2-23 eject the same ink, for example, yellow Y, different from the print heads 2-11, 2-12, 2-21, and 22. The print heads 2-14 and 2-24 eject the same ink, for example, black K, different from the print heads 2-11 to 2-13 and 2-21 to 23.

(Claim 1)
The printing apparatus shown in FIG. 4 also has a print control unit 3 as in the printing apparatus shown in FIG. The print control unit 3 includes an image input unit 4, an image conversion unit 5, a halftone processing unit 6, a nozzle drive unit 7, a conveyance control unit 8, an expansion rate estimation unit 9, and a head angle adjustment unit 10. The expansion coefficient estimation unit 9 constitutes means for acquiring the density to be printed on the print medium 1 for each different type of ink, and means for acquiring the type of the print medium 1. The head angle adjustment unit 10 determines each of the plurality of print heads 2-11 to 2-14 and 2-21 to 2-24 from print information, for example, print information including the density to be printed and the type of the print medium 1. A means for adjusting the angle between the nozzle arrangement direction and the medium conveyance direction is configured.

(Claim 1)
The operations of the image input unit 4, the image conversion unit 4, the image conversion unit 5, the halftone processing unit 6, the nozzle drive unit 7, the conveyance control unit 8, the expansion rate estimation unit 9, and the head angle adjustment unit 10 are basically illustrated. 1 is equivalent to that of the printing apparatus shown in FIG. However, the expansion coefficient estimation unit 9 acquires the density for each different type of ink, and the head angle adjustment unit 10 performs the same color print heads 2-11 and 2-21, 2-12 and 2-22, and 2- 13 and 2-23, 2-14 and 2-24, as well as the print heads 2-11 to 14 and 2-21 to 2-24 of different colors, the angle between the nozzle arrangement direction and the medium transport direction Adjust. As a result, it is possible to prevent printing deviation between colors as well as for each color. In order to adjust the angle, the passage times (average speed) of the print heads 2-11 to 2-14 and 2-21 to 2-24 are also taken into consideration.

(Claim 2)
The head angle adjusting unit 10 is a print head 2 that discharges a recording material to the print medium 1 prior to the other print heads among the print heads 2-11 to 2-14 and 2-21 to 2-24. For 11 to 2-14 and 2-21 to 2-23, the angle between the nozzle arrangement direction of the print head and the transport direction is adjusted in consideration of the density of the recording material to be printed later. That is, not only the expansion and contraction by the individual inks of the print heads 2-11 to 2-14 and 2-21 to 2-24, but also the subsequent print heads 2-12 to 2-14 and 2-22 to 2-24. The angle is adjusted in consideration of expansion and contraction due to ink. As a result, it is possible to prevent printing deviation with higher accuracy.

(Claim 3)
Furthermore, the head angle adjustment unit 10 precedes the nozzle row that discharges the highest density ink among the different types (colors) of the print heads 2-11 to 2-14 and 2-21 to 2-24. As for the nozzle array that ejects ink, the angle between the nozzle array direction and the transport direction is made to coincide with the angle between the nozzle array direction of the nozzle array that ejects the recording material with the highest density and the transport direction. Even if the amount of ink printed by a certain nozzle row is small, if a large amount of ink is ejected by the nozzle row immediately after, the expansion and contraction of the print medium 1 will increase. In such a case, the printing deviation can be prevented by adjusting the angle of the preceding nozzle row to the angle of the immediately following nozzle row.

  In the above description, the case where the order of ink to be printed is CMYK has been described as an example, but this order may be KCMY or another order. Further, it is possible to employ a configuration in which printing is performed by adding ink other than CMYK or adding other inks to CMYK by increasing the number of nozzle rows. Further, the repetition of the same ink is not limited to twice, but can be made only once or three times or more (usually a power of 2).

[Second Embodiment]
FIG. 5 is a block diagram of a printing apparatus according to the second embodiment of the present invention. This embodiment is different from the first embodiment shown in FIG. 4 in that the width direction of the print medium 1 is printed by a plurality of nozzle rows instead of one nozzle row. FIG. 5 shows only two print heads provided for each of the nozzle array groups 23a and 23b for the sake of simplicity. Actually, however, the nozzle array group 23a is similar to the printing apparatus shown in FIG. , 23b are provided with a plurality of sets of print heads for ejecting different types of ink.

  That is, the print heads 2-1a and 2-2a each having one nozzle row are arranged at different positions in the transport direction relative to the print medium 1, thereby forming a nozzle row group 23a. Similarly, print heads 2-1b and 2-2b each having one nozzle row are arranged to form a nozzle row group 23b. The nozzle row groups 23a and 23b are arranged in a direction crossing the medium transport direction. The print heads 2-1a, 2-2a, 2-1b, and 2-2b constituting the nozzle row groups 23a and 23b intersect with the medium conveyance direction in the same manner as the nozzle rows 2-1 and 2-2 shown in FIG. Ink is ejected onto the print medium 1 from a plurality of nozzles arranged along the direction of the ink.

  The printing apparatus shown in FIG. 5 also has a print control unit 3 as in the printing apparatus shown in FIG. The print control unit 3 includes an image input unit 4, an image conversion unit 5, a halftone processing unit 6, a nozzle drive unit 7, a conveyance control unit 8, an expansion rate estimation unit 9, and a head angle adjustment unit 10. A position adjustment unit 11 is provided. The head angle adjusting unit 10 is configured for at least one nozzle row of each of the print heads 2-1a, 2-2a, 2-1b, 2-2b in the nozzle row groups 23a, 23b based on the expansion rate of the print medium 1. A means for adjusting an angle between the nozzle arrangement direction and the medium conveyance direction is configured. The head position adjustment unit 11 constitutes means for moving the nozzle array groups 23a and 23b in directions that intersect the medium conveyance direction.

  FIG. 6 is a diagram illustrating an example of the arrangement of the print heads 2-1a, 2-2a, 2-1b, and 2-2b of the printing apparatus illustrated in FIG. Here, description will be made assuming that the same product is used as the print heads 2-1a, 2-2a, 2-1b, and 2-2b.

  When printing the width direction of the print medium 1 with a plurality of print heads 2-1a, 2-1b and 2-2a, 2-2b, even if the print medium 1 is expanded or contracted, the nozzle array groups 23a and 23b The head angle adjustment unit 10 is configured so that the print heads 2-1a, 2-2a, 2-1b, and 2-2b have substantially the same print resolution. The angles 1b and 2-2b are controlled. Further, the head position adjustment unit 11 adjusts the interval between the nozzle row groups 23a and 23b so that the printing resolution does not change between the nozzle row groups 23a and 23b.

  Further, the head position adjustment unit 11 performs printing by a print head (print heads 2-1a and 2-1b in the example of FIG. 6) having a nozzle row having the largest angle with the medium conveyance direction in the nozzle row groups 23a and 23b. The interval between the nozzle row groups 23a and 23b is adjusted so that the resolution and the printing resolution between the nozzle row groups are equal. Thus, when adjusting the space | interval of the nozzle row groups 23a and 23b, in the print heads 2-2a and 2-2b other than the print heads 2-1a and 2-1b having the largest angle in the nozzle row groups 23a and 23b, Between the nozzle row groups 23a and 23b, the nozzle interval is smaller than the other position nozzle intervals. For this reason, if the printing is performed as it is, the portion becomes dark. Therefore, for this portion, the ink density is adjusted between the nozzle rows 2-2a and 2-2b. Specifically, the ink amount is reduced in the portion where the nozzle interval is small.

  FIG. 7 is a diagram illustrating an example different from FIG. 6 of the arrangement of the print heads 2-1a, 2-2a, 2-1b, and 2-2b of the printing apparatus shown in FIG. Here, it is assumed that the same product is used as the print heads 2-1a, 2-2a, 2-1b, and 2-2b.

  In this example, the head angle adjustment unit 10 controls the angles of the print heads 2-1a, 2-2a, 2-1b, and 2-2b in the nozzle row groups 23a and 23b separately. In other words, the expansion rate estimation unit 9 calculates the average density of the image, that is, the ink ejection amount, for each area printed by each of the nozzle row groups 23a and 23b. Then, the head position adjusting unit 11 tilts the print head (print head 2-1a in the example of FIG. 7) larger than the print head 2-1b in the region where the ink hit amount is large.

  Also in this case, as described with reference to FIG. 6, the head position adjusting unit 11 is configured so that the print resolution is substantially equal even when the print medium 1 is expanded or contracted. The angle of 2-2a, 2-1b, 2-2b is controlled. Further, the head position adjustment unit 11 adjusts the interval between the nozzle row groups 23a and 23b so that the printing resolution does not change between the nozzle row groups 23a and 23b. In the print heads 2-2a and 2-2b other than the print heads 2-1a and 2-1b having the largest angle with the direction orthogonal to the medium transport direction in the nozzle row groups 23a and 23b, the ink density between the print heads 2-2a and 2-2b. Adjust.

  In the above description, the print control unit 3 is described as being provided in the printing apparatus. The print control unit 3 can also be implemented as a printer driver that operates on a computer. That is, a plurality of print heads 2-1 and 2-2 are provided at different positions in the transport direction relative to the print medium 1, and the plurality of print heads 2-1 and 2-2 intersect with the transport direction, respectively. A program installed in a computer to which a printing apparatus having a plurality of nozzles for ejecting ink onto the printing medium 1 is connected along the direction in which the printing medium 1 is ejected.

  In the above description, an example having one row of nozzles in one print head has been described. However, depending on the nozzle arrangement, a configuration in which two or more rows of nozzles are provided in one print head may be employed. In this case, the angle between the nozzle arrangement direction and the medium conveyance direction is determined for each print head. A positional shift occurs between the nozzle rows in a direction perpendicular to the medium transport direction. For example, when the nozzle rows are close to each other, the shift can be ignored.

  In the configuration described above, the effect is large and preferable when the ink is a water-based ink having a viscosity close to that of water, but the present invention can be applied to other inks such as oil. In addition, since the degree of expansion and contraction varies greatly depending on the direction of the fiber of the paper, the eyes of the paper are automatically detected, and the angle of the nozzle row is adjusted only when the direction of large expansion and contraction is the width direction. Also good. Furthermore, the present invention is preferably applied to high-precision printing such as gravure printing, but can also be applied to text printing and text-based printing.

  1 print medium, 2-1, 2-2, 2-11 to 2-14, 2-1a, 2-1b, 2-2a, 2-2b print head, 3 print control unit, 4 image input unit, 5 image Conversion unit, 6 Halftone processing unit, 7 Nozzle drive unit, 8 Transport control unit, 9 Expansion rate estimation unit (means for acquiring density, means for acquiring type), 10 Head angle adjustment unit (means for adjusting angle) , 11 Head position adjustment unit, 21, 22 Nozzle row, 211-1 to 21-10, 22-1 to 22-10 Nozzle, 23a, 23b Nozzle row group

Claims (5)

There are a plurality of nozzle rows that discharge different types of recording materials at different positions in the transport direction relative to the print medium, and each of the plurality of nozzle rows is arranged along a direction that intersects the transport direction. A printing apparatus having a plurality of nozzles,
Means for acquiring the density to be printed on the print medium for each of the different types of recording materials;
Means for obtaining the type of the print medium;
Means for adjusting an angle between the nozzle arrangement direction and the transport direction for each of the plurality of nozzle rows from the print information including the density to be printed and the type of the print medium. Printing device.   2. The printing apparatus according to claim 1, wherein the adjusting unit prints a nozzle row that discharges a recording material onto the print medium prior to another nozzle row from among the plurality of nozzle rows. In consideration of the density of the recording material to be printed, the angle between the nozzle arrangement direction of the nozzle row and the transport direction is adjusted.   3. The printing apparatus according to claim 2, wherein the adjusting unit discharges the recording material ahead of the nozzle row that discharges the recording material having the highest density among the different types of recording materials among the plurality of nozzle rows. With respect to the nozzle row, the angle between the nozzle array direction and the transport direction is made to coincide with the angle between the nozzle array direction of the nozzle row that discharges the recording material with the highest density and the transport direction. Printing device. A plurality of nozzle rows that discharge different types of recording materials are arranged at different positions in the conveyance direction relative to the print medium, and each of the plurality of nozzle rows is arranged along a direction that intersects the conveyance direction. A printing method for discharging the recording material by a plurality of nozzles,
Obtain the density to be printed on the print medium for each of the different types of recording materials,
Get the type of print media
A printing method comprising adjusting an angle between the nozzle arrangement direction and the transport direction for each of the plurality of nozzle rows from print information including the density to be printed and the type of the print medium. A program for controlling a printing apparatus connected to the computer by installing the computer,
The printing apparatus has a plurality of nozzle rows that eject different types of recording materials at different positions in the conveyance direction relative to the print medium, and each of the plurality of nozzle rows intersects the conveyance direction. A plurality of nozzles arranged along
Means for acquiring a density to be printed on the print medium for each of the different types of recording materials;
The angle between the nozzle arrangement direction and the transport direction is determined for each of the plurality of nozzle arrays from the print information including the means for obtaining the type of the print medium and the density to be printed and the type of the print medium. A program for operating the computer as a means for adjusting.

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