JPH07117241A - Ink jet recording method - Google Patents

Abstract

PURPOSE:To eliminate line-variation that is easily generated in the boundary section of the printed portion printed by adjacent nozzles in a multi-nozzle ink jet printer and to obtain the highly uniform printing. CONSTITUTION:A recording method of a multi-nozzle ink jet recorder is disclosed hereinafter. The widths of printable areas of nozzles 2 are overlapped such that the overlapping width (We) is 0.5mm or more in the adjacent nozzles 2, 2. Dot patterns to be printed by the adjacent nozzles are varied in the printing direction in the overlapping width (We) by dividing in two alternately and the repeating cycle L of the variation is 0.5 to 8 times of the overlapping width (We).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording method which enables uniform printing without streaks on a recording material in multi-nozzle ink jet recording.

[0002]

2. Description of the Related Art Ink jet recording is being put to practical use in the field of paper printers. However, there are various problems when it is applied to a field requiring high-speed printing on a wide recording material such as dyeing of cloth.
In general, when an inkjet recording method is applied to such a wide recording material, multi-nozzling is required, and various proposals have already been made. Among them, a method called a charge deflection type multi-nozzle method (for example, Japanese Patent Laid-Open No. 47-58).
No. 61), the printing position can be controlled by changing the amount of electric charge applied to the ink droplets ejected from one nozzle, so that the printing width can be increased with a small number of nozzles and high-speed printing can be performed on a wide recording material. It is considered to be suitable as a method of doing.

However, a problem with this charge-deflection-type multi-nozzle system is that it has a drawback that streaky unevenness is likely to occur at the boundary between adjacent nozzles in the printed portions. That is, when the print dots are too close to each other or overlap each other at the boundary between the adjacent nozzles, dark streaks are generated, and when they are too far apart from each other, white streaks are generated, which are conspicuous. Such streaking is fatal especially when applied to a cloth, and the commercial value is remarkably reduced.

As a measure to eliminate such streaking,
In addition to improving the accuracy of the printing position, some methods have been proposed to make the boundary between the printing portions between adjacent nozzles not zigzag but zigzag to make them inconspicuous. For example, in Japanese Patent Laid-Open No. 55-42836, the boundary of the printed portion between adjacent nozzles is made to overlap by one dot or more, and
It has been proposed to print on both nozzles alternately.
Further, in Japanese Patent Laid-Open No. 2-62243, it is proposed to print the overlapping portion randomly. However, none of these methods has been a measure that can completely avoid streaking, especially when applied to fabrics.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate streaking, which is likely to occur at the boundary of a print portion between adjacent nozzles in multi-nozzle ink jet recording, and to realize highly uniform printing. To provide. Another object of the present invention is to provide an ink jet recording method that enables highly uniform dyeing of wide recording materials such as cloths having particularly high fiber orientation.

[0006]

SUMMARY OF THE INVENTION The present invention for achieving the above object provides a multi-nozzle ink jet recording method in which a plurality of nozzles are arranged and ink droplets ejected from these nozzles are printed on a recording material. The possible widths are overlapped between adjacent nozzles with an overlapping width We of at least 0.5 mm, and the dot patterns for printing of the adjacent nozzles are changed while being distributed in the printing direction in the area of this overlapping width We, and the repetition cycle of the change L is the overlapping width W
e is 0.5 to 8 times.

In this way, the printable widths of the respective nozzles are made to overlap each other with an overlapping width We of a certain value or more between adjacent nozzles, and the dot patterns of the adjacent nozzles are changed by the overlapping width We and are changed. By making the repetition period L of (1) constant with respect to the overlapping width We, it becomes possible to make the streak unevenness inconspicuous at the boundary between mutually printed portions.

A detailed description will be given below with reference to the drawings. As an example of the multi-nozzle inkjet system applied to the present invention, FIG. 1 shows a case of a charge amount deflection type multi-nozzle inkjet. In the illustrated example, the plurality of nozzle heads 10 face the cloth (recording material) 20, and the cloth 2
They are arranged in a line shape at regular intervals in the width direction of 0. Although the number of nozzle heads 10 is three in the figure for easy understanding, a larger number of nozzle heads 10 are actually arranged.

Each nozzle head 10 is provided with a pressure element 1 and a nozzle 2. The ink pressure-fed to the nozzle head 10 is excited by the pressure element 1, divided into ink droplets corresponding to the number of excitations, and ejected from the nozzle 2. The ink droplets ejected from the nozzles 2 are applied with a charge corresponding to an image to be printed on the cloth 20 by the charging electrode 3, and then are deflected by the deflection electrode 4 according to the amount of electric charge and printed on the cloth 20. The ink droplets to which no electric charge is applied are collected by the gutter 5 and recirculated to the nozzle head 10.

In the multi-nozzle ink jet system, as shown in FIG. 1, a plurality of nozzle heads 10 are arranged in the width direction of a recording material 20 such as a cloth so as to be separated by the printing width of the nozzles 2. It is possible to print by running only the recording material 20 while the nozzle head 10 is fixed. This is called the line head method. On the other hand, when the number of nozzles is small and the printing width of each nozzle is narrow, a plurality of nozzle heads are arranged in the longitudinal direction of the recording material and are reciprocally moved in the width direction to print in the width direction. It is also possible to print by intermittently feeding the recording material sequentially by the print width each time. This is called a nozzle moving method as opposed to the line head method.

The printing direction in the present invention means the printing direction of the nozzle array, which is the running direction (feeding direction) of the recording material in the case of the line head system and the nozzle moving direction (recording in the case of the nozzle moving system). The width direction of the material). The direction perpendicular to the printing direction is called the nozzle row direction, and in the charge amount deflection type multi-nozzle inkjet shown in FIG. 1, it corresponds to the direction in which droplets from each nozzle are deflected and scanned.

In both the line head system and the nozzle movement system, a plurality of nozzles share images to draw an image. Normally, one nozzle draws a band-shaped image, so that the boundary between adjacent nozzles is drawn. The lines are straight. In the multi-nozzle inkjet system having such characteristics, the present invention makes the printable widths of the respective nozzles overlap with each other between adjacent nozzles as will be described below in detail, and Change the print dot pattern while allocating to each other in the print direction,
The repetition cycle of the change is determined in relation to the overlapping width of the print width.

FIG. 5 shows a model of dots printed by two adjacent nozzles A and B. In the figure, the print of the nozzle A is shown as a white dot and the print of the nozzle B is shown as a hatched dot for easy understanding, but the same ink is actually used. As shown in (a) of FIG. 5, when the dots of the nozzles A and B can be printed with high accuracy, the boundary between both printing portions cannot be separated, and the color has high uniformity. However, as shown in FIG. 5B, when the print dots of the nozzles A and B deviate in the direction away from each other for some reason, a gap occurs at the boundary between the two print portions, and whitening occurs.
It becomes thin and appears as streaks that are not colored. On the other hand, if the print dots approach or overlap, dark streaks occur.

On the other hand, according to the proposal of Japanese Patent Application Laid-Open No. 55-42836, as shown in FIG. 5C, the boundary between both print portions of the nozzles A and B is overlapped by one line of X. In addition, if the dots are alternately printed one by one between the nozzles A and B, it is said that even if the print dots are displaced as shown in FIG.

However, according to the results of the investigations made by the present inventors on the above countermeasures, since the actual print dots are very small, the effect of making streaks inconspicuous is hardly recognized as long as the alternate print is one dot. I understood. In addition, when the overlapping portions of the printing portions of the nozzles A and B are increased and the multi-dot 1-dot alternating printing is performed, the misalignment in the printing direction (vertical direction in the figure) is conspicuous, and the stepwise horizontal streaks occur. Is likely to occur.

Further, in the method of randomizing the printing of overlapping portions disclosed in JP-A-2-62243, when the method is applied to printing (dyeing) on a fabric such as a woven fabric, the constituent fibers are random like paper. Since it has a structure in which the vertical and horizontal lines are alternately arranged at a substantially right angle instead of the normal arrangement, vertical and horizontal lines can occur due to slight misalignment in printing.
Even with random printing means, there remains a problem that streaks are likely to occur partially.

The inventors of the present invention have studied the relationship between the overlapping condition of the printed portions between the adjacent nozzles and the streak unevenness, particularly in the case of cloths, and as a result, in order to make the streak unnoticeable, It has been found that it is important to specify the size of the overlapping width of the printed portion and the shape of the boundary between the two dot patterns in relation to the appearance with the naked eye. That is, the overlapping width We of the print width of each nozzle between the adjacent nozzles is
It is necessary to increase the width to some extent or more, and the overlapping width We is to be 0.5 mm or more, preferably 1 mm or more. Although this depends on the resolution, the number of dots is 3 dots or more, preferably 6 dots or more. The upper limit of the overlapping width We is not particularly limited, but it is not necessary to unnecessarily increase it due to economic factors, and it is preferably about 5 mm, and in the case of the number of dots, it is about 40 dots.

Further, in the area of this overlapping width We, the boundary of the print dot pattern of each nozzle is changed while being distributed in the print direction. The repetition cycle L of the change needs to be increased to some extent or more instead of alternating one dot at a time as in the conventional example, and the overlapping width We
0.5 to 8 times, preferably 1 to 4 times.

FIG. 2 is a conceptual diagram showing an example of a dot pattern formed between adjacent nozzles in the ink jet recording method according to the present invention. In FIG. 2, the printable width of the nozzle A is Wa, and the printable width of the nozzle B adjacent to the nozzle A is Wb. Both of the printable widths Wa and Wb periodically and continuously change in the printing direction, and the boundary between them becomes a zigzag shape as shown by a thick line, and the overlapping width W at the zigzag portion.
It overlaps with e. That is, in the overlapping width We, the print dot patterns of the adjacent nozzles A and B are changed while being distributed in the print direction.

As mentioned above, the overlapping width We is 0.5 to 5 mm.
Therefore, the number of dots is set to about 3 to 40 dots.
In the area of the overlapping width We, the dot patterns of both nozzles A and B are changed to be distributed to any one of the arbitrary patterns, but from a practical point of view, the dot pattern is allocated to a repeating period pattern using the full overlapping width. To do so. The repetition cycle L of the distribution change of the dot pattern is 0.5 to 8 times the overlapping width We.

FIG. 3 shows an example of the distribution of the print dot pattern of each nozzle between the adjacent nozzles A and B. The overlap width We is overlapped by 5 dots and has a zigzag shape of about 45 degrees. Have been sorted out. Further, the repetition cycle L in the printing direction is 10 dots (twice the overlapping width We)
It has become. In this way, in the area of the overlapping width We,
By varying the dot patterns of the adjacent nozzles with each other, it is possible to make streaks less noticeable at the boundary between the two dot patterns. Such effects of the present invention are
The overlapping width We of the printable width and the repetition cycle L of the change of the dot pattern in the printing direction are set as described above, and
Furthermore, it is possible to further improve the number of print dots of the dot pattern of one nozzle by making the number of print dots not constant in the print direction but constantly changing.

When the recording material is a cloth, depending on its weave design, when it is a plain weave, the distribution boundary is around 45 degrees with respect to the printing direction, that is, the repetition period L is the overlapping width W.
It is possible to make the streak most inconspicuous when it is set to about twice e. Further, the boundary line formed between the print dot patterns of both nozzles is not necessarily a linear zigzag shape as shown in FIG. 2, but may be a curved shape as shown in FIG. Alternatively, as long as the conditions of the overlapping width We and the repetition period L are satisfied, appropriate randomness may be given in dot units to give randomness.

Further, in the present invention, the print dot pattern of each nozzle is preferably symmetrical with respect to the center line CL, as in the examples of FIGS. That is, it is desirable to have a shape in which the number of print dots (that is, print width) with respect to the print direction constantly changes. Although the reason for this has not been clarified yet, by constantly changing the number of print dots in the print direction in this way, the unevenness of the boundary is made less noticeable. Further, when the repeating cycle L of the change in the printing direction is set to be approximately twice the overlapping width We, the streak can be made most inconspicuous.

Although the above description has been made mainly for the case of the line system of the charge amount deflection type multi-nozzle, the present invention is applied to the nozzle moving system printing, and the printing portion at the bottom in the feeding direction of the recording material and the next printing portion. It can also be applied to the uppermost printed portion printed on. Further, the same can be applied to the on-demand method. Furthermore, it can be applied to the case of printing in multiple colors. When the present invention is applied to the case of printing in multiple colors, it is advisable to shift the boundaries of the dot patterns formed between the adjacent nozzles of each color nozzle row. Alternatively, it is preferable to form different dot patterns for each nozzle row of each color so that the boundaries do not coincide with each other.

In the present invention, the means for allocating and changing the dot pattern in the area of the overlapping width of the printing width of the adjacent nozzles is not particularly limited as long as the hardware is designed to allow overlapping printing. That is,
A means for distributing each dot data of the image as the software or the hardware can be performed by a known method.

[0026]

【Example】

Example 1 Using a charge amount deflection type inkjet printer having the same principle as that of FIG. 1 having the following specifications, the following dyeing of a woven fabric was performed. (Printer specifications) Number of colors: 4 colors Color resolution: 6.4 dots / mm Nozzle configuration: Multi-nozzle system with 12 nozzles per color
(12 cm width printing) It is designed to have a printable width of 12.5 mm width (80 dots) per nozzle. If the printing width is 10 mm width (64 dots) per nozzle, it is possible to print without overlapping.
Dot (2.5 mm) is the overlap printable area.

The print pattern of the overlapping portion is the pattern shown in FIG. 2 (the period L is 32 dots) Nozzle diameter: 70 μm Printing method: Nozzle moving method In the above jet printing, the disperse dye ink is used as the ink and the recording material is used. Polyester fabric (Toray, "Silook" satin) is used as a pretreatment liquid
Using Neofix RX-100, 20 g / liter, pretreatment for preventing bleeding was performed by pad-dry processing, and a black solid pattern was printed. Next, after color development with an HT steamer by a conventional method, reduction washing was performed, and after drying, the presence or absence of streaks was visually inspected by the following method.

That is, it was evaluated by how much the streaks were conspicuous when the print dots deviated from the normal position. As a result, in the case of no overlapping printing, white streaks were conspicuous at a deviation of about 60 μm, but in the dyeing method of the present invention, almost no streaks were found at a deviation of 60 μm. 80μ
The streaks were less noticeable even when misaligned by m, indicating high dyeing uniformity.

Example 2 In Example 1, the width of the overlapping portion in the print dot pattern of FIG. 2 was set to 1 dot (0.16 mm) and 2 dots.
(0.31mm), 4 dots (0.62mm), 8 dots
(1.25 mm) and 16 dots (2.5 mm) were changed to evaluate the degree of white stripes.

As a result, 60 μ in case of 2 dots or less
White streaks were observed at a deviation of m, but it was found that when the number of dots is 4 dots or more, it becomes visually inconspicuous. Comparative Example 1 A polyester woven fabric was dispersed in the same manner as in Example 1 using a charge amount deflection type, which has the same principle as in FIG. 1, a resolution of 8 dots / mm, a nozzle diameter of 50 μm, and a 4-nozzle multi-nozzle continuous inkjet printer. When printing with dye ink, the width of the overlapping portion in the print dot pattern is 1 dot (0.16 mm) and 8 dots (1.25 mm), respectively.
mm) and 16 dots (2.5 mm), and the overlapping portion was alternately printed between adjacent nozzles according to the method of JP-A-55-42836.

As a result, when one dot overlapped, white streaks were recognized with a deviation of 60 μm. At 8 dots and 16 dots, streaks considered to be caused by nozzle misalignment in the printing direction were noticeable. When the print position was intentionally shifted in the nozzle direction, a shift of about 30 μm was recognized as a streak. Comparative Example 2 When performing the same printing as in Comparative Example 1, JP-A-2-6
The overlapping portion was randomly changed between the adjacent nozzles according to the method disclosed in Japanese Patent No. 2243.

As a result, white stripes were recognized in the same manner as in Comparative Example 1 when 1 dot was overlapped. Further, with 8 dots and 16 dots, the effect of improving white streaks was recognized as compared with Comparative Example 1, but white streaks were observed here and there.

[0033]

As described above, according to the present invention, in the multi-nozzle ink jet recording method, the printable widths of the respective nozzles are overlapped with each other with the overlapping width We of at least 0.5 mm, and the overlapping is performed. By changing the print dot patterns of the adjacent nozzles in the area of the width We while allocating the print dot patterns to each other and making the repetition cycle L of the change 0.5 to 8 times the overlapping width We, the boundary between the print portions of each other. It is possible to make the stripes inconspicuous.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a charge amount deflection type inkjet printer of a multi-nozzle inkjet method applied to the present invention.

FIG. 2 is a conceptual diagram showing an example of a print dot pattern in an overlapping portion of printable width according to the present invention.

FIG. 3 is an explanatory diagram in which an example of the same print dot pattern is displayed in dots.

FIG. 4 is a conceptual diagram showing another example of the print dot pattern in the overlapping portion of the printable width in the present invention.

5A to 5D are explanatory diagrams showing a model of dots printed by the adjacent nozzles A and B. FIG.

[Explanation of symbols]

1 Pressure Element 2 Nozzle 3 Charging Electrode 4 Deflection Electrode 5 Gutter 10 Nozzle Head 20 Cloth (Recording Material)

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Claims (5)

[Claims] 1. A multi-nozzle inkjet recording method in which a plurality of nozzles are arranged and ink droplets ejected from these nozzles are printed on a recording material, and the printable width of each nozzle overlaps by at least 0.5 mm between adjacent nozzles. Width We
And the dot patterns for printing of the adjacent nozzles are changed while being distributed in the printing direction in the area of the overlap width We, and the repetition cycle L of the change is made 0.5 to 8 times the overlap width We. Inkjet recording method. 2. The ink jet recording method according to claim 1, wherein printing of three dots or more is interposed in the overlapping width We in the nozzle row direction. 3. The ink jet recording method according to claim 1, wherein the recording material is cloth, and the cloth is dyed by the multi-nozzle ink jet recording method. 4. The ink jet recording method according to claim 1, wherein the number of dots in the nozzle row direction of the print dot pattern of each nozzle is constantly changed in the overlapping area We between the adjacent nozzles. 5. In ink jet recording for printing in multiple colors, the boundaries of dot patterns formed between adjacent nozzles of nozzle rows of each color are offset from each other, or different dot patterns are formed so that the boundaries are offset from each other. The inkjet recording method according to claim 1, 2, 3, or 4.