JP2002326344A - Method for controlling ink jet printer for textile printing and printing method for ink jet printer for textile printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for controlling an ink jet printer for textile printing which eliminates a moire and which maintains the density of a color on a cloth which has much ink absorption amount such as, for example, a towel, a moquette or the like, and a method for printing the ink jet printer for textile printing. SOLUTION: The method for controlling the ink jet printer for textile printing comprises a step of changing an adhering position of the cloth of an ink drop discharged from a head when the moire is generated on the cloth textile printed by the ink jet printer for textile printing, a step of changing a look-up table LUT in response to the changed adhering position, and a step of changing input data used in a pseudo-gradation process. Thus, the textile printed color can be maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method of an ink jet printer for printing and a printing method of the ink jet printer for printing.

[0002]

2. Description of the Related Art Ink jet printers have low noise and are easy to colorize.
It is rapidly spreading as an output device for personal use. In particular, in recent years, application to textile printing of an ink jet printer is expected from the viewpoint of environment and QR. Ink-jet printing printers use water-based inks for cotton and silk, which are one type of fabric, and disperse disperse dyes into fine particles for printing of another type of fabric, such as chemical fibers (such as polyester). Used disperse dye ink. Pigment inks are also expected as inks of any cloth type.

[0003]

However, when performing printing with an ink jet printer, there is a problem of moire with respect to a cloth having a small amount of ink absorption, such as a scarf or a handkerchief, having a low density of weaving. Such moiré will be described.

Generally, image processing in an ink jet printer is performed by an area gradation method. That is, the color to be printed is determined by setting the number of ink drops ejected per unit area. Here, in the dither method, which is a kind of image processing, it is known that moiré occurs due to a cycle corresponding to the pattern of the ink drop, and the cycle interfering with the weaving cycle of the fabric. On the other hand, in the error diffusion method, which is another type of image processing, if a certain gradation is determined, a certain cycle still occurs and moire occurs. Regarding the cause of such moiré,
This is described in detail in JP-A-10-8386.

In order to solve such a problem of moire, Japanese Patent Laid-Open Publication No. Hei 6-10278 proposes a method of using colorless ink to avoid moire by bleeding. However, such a method has a problem that the high definition which is a feature of the ink jet printer cannot be maintained. On the other hand, Japanese Patent Application Laid-Open No. 10-8386 proposes a method of printing while changing the interval at which the cloth is sent. In this method, a color change occurs due to a change in dot interval, and there is a problem in color reproducibility. Such problems are:
It occurs more remarkably for a fabric such as a towel or a moquette that has a large ink absorption amount.

The present invention has been made in view of the above-mentioned problems of the prior art, and eliminates moire and maintains the color density even for a cloth such as a towel or a moquette that has a large amount of ink absorption. An object of the present invention is to provide a control method of an ink jet printer for printing and a printing method of the ink jet printer for printing.

[0007]

According to a first aspect of the present invention, there is provided a method of controlling an ink-jet printing printer for textile printing, comprising: a head for discharging ink drops movable in a main scanning direction and a sub-scanning direction; And a control unit for changing to the head drive data based on the pseudo gradation method, the method for controlling a printing ink jet printer, wherein when the moire occurs in the fabric printed by the printing ink jet printer, the moire is discharged from the head. In the pseudo-gradation method, the step of changing the adhesion position of the changed ink drop on the cloth, the step of changing the look-up table in accordance with the changed adhesion position, and the step of changing the adhesion position Changing the input data to be used.

According to a second aspect of the present invention, there is provided a printing method for a textile ink jet printer, comprising a head for discharging ink drops, wherein the resolution in at least one of a main scanning direction and a sub scanning direction can be changed within a predetermined range. The minimum resolution is the reciprocal of the dot diameter ejected from the head and formed on the fabric × √2, and the maximum resolution is the L value between the maximum resolution and a smaller resolution. Is at least L
It is characterized in that it is when <1.

[0009]

According to a first control method of an ink jet printer for textile printing of the present invention, an ink drop discharge head movable in a main scanning direction and a sub-scanning direction, and image data are converted into a look-up table and a pseudo gradation method. A control unit that changes to the head drive data based on the control method of the inkjet printer for textile printing, wherein, when moiré occurs in the fabric printed by the inkjet printer for textile printing, the ink drop ejected from the head, Changing the attachment position on the fabric, and changing the look-up table according to the changed attachment position;
Changing the input data used in the pseudo gradation method according to the changed attachment position,
For example, when the pattern of the ink drop and the weaving cycle of the fabric interfere with each other and moiré occurs, the moiré is eliminated by changing the attachment position of the ink drop ejected from the head on the fabric or Suppressing, and changing the look-up table according to the changed adhesion position, and changing the input data used in the pseudo gradation method according to the changed adhesion position, thereby changing the color to be printed. Can be maintained.
The input data used in the pseudo gradation method refers to, for example, composite data of color density and hue.

Further, it is preferable that the pseudo gradation method can automatically select an error diffusion and / or a dither method. The error diffusion and the dither method are well-known techniques in the field of image processing, and therefore, the details are omitted.

When the same look-up table is applied to similar types of cloths, it is not necessary to create a look-up table for all kinds of cloths, which is convenient. The weaving is defined by the number per unit mm, and those within ± 30% with respect to the standard can be regarded as similar cloths. ± 3 for thread thickness
If it is within 0%, it can be regarded as similar. Further, if the number of yarns constituting the yarn is ± 20%, it can be seen that they are similar.

According to a second aspect of the present invention, there is provided a printing method for a textile ink jet printer, comprising a head for discharging ink drops, wherein the resolution in at least one of a main scanning direction and a sub scanning direction can be changed within a predetermined range. The minimum resolution is the reciprocal of the dot diameter ejected from the head and formed on the fabric × √2, and the maximum resolution is the L value between the maximum resolution and a smaller resolution. Is at least L
Since it is <1, moire can be effectively suppressed while maintaining image quality. The L value here is a perceived chromaticity index defined in the CIE1976 (L, a, b) space.

Further, the resolution is changed by changing the attachment position of the ink drops ejected from the head on the cloth, and the minimum resolution is formed by the maximum number of the ejected ink drops. The maximum resolution is the reciprocal of the dot diameter formed by one ink drop × √2 or more, and the difference between the L values at the immediately preceding variable resolution is at least L. It is preferable to be <2. The present invention provides, for example, one dot, two dots,
The minimum resolution and the maximum resolution in the case of a variable dot type such as three dots are defined by an ink jet printer for textile printing. That is, in the variable dot inkjet, when the variable dot is stopped and fixed, the dpm is determined in accordance with the fixed variable dot (see Example 4 described later).

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a mechanical configuration of a main part in an ink jet printer for textile printing according to the present embodiment.

Referring to FIG. 1, the ink jet printer 22 for textile printing will be described. The carriage 2 is a resin case housing the head 10 and a head driver (not shown). A head driver (not shown) housed in the carriage 2 is composed of, for example, an IC, and is connected to the control board 9 by a flexible cable 5 pulled out from the carriage 2. The control board 9 is communicably connected to a personal computer 21 for image processing. Control board 9
And the personal computer 21 constitute a control unit.

The carriage 2 is reciprocated by the carriage driving mechanism 6 in the main scanning direction (X direction) indicated by an arrow in the figure. The carriage drive mechanism 6 includes a motor 6a, a pulley 6b, a toothed belt 6c, and a guide rail 6d, and the carriage 2 is fixed to the toothed belt 6c.

When the pulley 6b is rotated by the motor 6a, the carriage 2 fixed to the toothed belt 6c is moved in the direction of the arrow X in the figure. Guide rail 6d
Are two columns parallel to each other and penetrate through the insertion hole of the carriage 2 so that the carriage 2 slides.

For this reason, the toothed belt 6c is
The carriage 2 does not bend under its own weight, and the direction of reciprocation of the carriage 2 is on a straight line. The direction in which the carriage 2 moves can be changed by reversing the rotation direction of the motor 6a, and the moving speed of the carriage 2 can be changed by changing the number of rotations. The ink cartridge (not shown) has an ink tank inside. The ink supply port of the ink tank is opened when the ink cartridge is set on the carriage 2 and connected to the ink supply pipe. When the connection is released, the ink supply port is closed and the ink is supplied to the head 10.

A head 10 is provided on the carriage 2. On the back surface of the head 10, Y, M,
Ink cartridges containing inks of the respective colors C and K are detachably arranged. The illustration of the ink cartridge is omitted. Flexible cable 5
Is a data transfer means, which prints a wiring pattern including a data signal line, a power supply line, etc. on a flexible film, transfers data between the carriage 2 and the control board 9, Follow the movement.

The encoder 7 is provided with graduations at a predetermined interval on a transparent film of resin.
Detects the moving speed, position, and moving direction of. The transport mechanism 8 is a mechanism for transporting the fabric P in the sub-scanning direction indicated by an arrow Y in the figure, and includes a transport motor 8a and transport roller pairs 8b and 8c. The transport roller pair 8b and the transport roller pair 8c are driven by the transport motor 8a, and are a pair of rollers that are substantially equal by a gear train (not shown), but rotate at a slightly higher peripheral speed.

The cloth P is sent out from a supply mechanism (not shown) and is nipped by a pair of conveyance rollers 8b rotated at a constant speed, and the conveyance direction is changed in the sub-scanning direction by a supply guide (not shown). After being corrected, the sheet is conveyed while being nipped by the conveying roller pair 8c.

Since the peripheral speed of the pair of conveying rollers 8c is very slightly higher than that of the pair of conveying rollers 8b, the cloth P passes through the recording section without causing slack. The speed at which the cloth P moves in the sub-scanning direction is set to a constant speed.

In this manner, while moving the fabric P at a constant speed in the sub-scanning direction, the carriage 2 is moved at a constant speed in the main scanning direction, and the ink ejected from the head 10 is adhered to a predetermined surface of one side of the fabric P. Record the image in the area. In the present embodiment, the resolution in the main scanning direction can be changed by changing the moving speed of the carriage 2, and the resolution in the sub-scanning direction can be changed by changing the rotation speed of the pair of transport rollers 8b. I have.

An example using this embodiment will be described below. (Embodiment 1) A method for eliminating moiré will be described with reference to the flowchart of FIG. First, step S10
In step 1, the customer uses the inkjet printer 22 for textile printing to obtain a recommended resolution (recommended resolution is the resolution if the customer can predict moiré avoidance based on the number of fabrics. Print at an appropriate resolution), develop color, wash and dry (hereinafter, post-processing), and check for moire. If moire has occurred, the ejection timing of the ink drop with respect to the position of the carriage 2 is changed, or the ejection timing of the ink drop with respect to the rotational position of the transport roller pair 8b is changed (step S102). Changing these ejection timings means changing the positions where the ink drops adhere to the fabric. However, simply changing only the resolution in this way results in different colors for printing. Therefore, the following processing is performed together.

First, a look-up table (Look) used when converting image data into head drive data.
An Up Table (hereinafter, referred to as an LUT) is newly created (or changed). The LUT is used by being stored in the personal computer 21. The method of changing the LUT is roughly divided into two steps S103 and S1 as shown in process A of FIG.
04.

In the first step S103, the gradation of each color constituting the print color is adjusted. When the resolution is changed as described above, the maximum density differs. Therefore, the gradation is not linear and the color balance is lost. For example, in the case of 256 gradations, the image is divided into 32 and the gradation is adjusted. Here, the corrected gradation data is obtained by simply printing each color with the data divided into 32, performing post-processing, measuring the color, digitizing the colors, and correcting the colors to have a linear gradation. (Gradation curve data) is created.

In the second step S104, a color combination patch constituting a print is measured from the corrected gradation data. Based on this data, an LUT is created by performing color interpolation, and stored in color conversion software.
The above processing can be performed by the personal computer 21.

Further, in step S105, different data depending on the combination of color density and color is input to the personal computer 21 as input data used for the error diffusion method. In step S106, the customer again prints the desired image on the fabric by the error diffusion method based on the changed LUT and the changed input data. In step S107, the customer visually determines and, if moire has occurred, changes the resolution again and performs the same processing in step S102, and terminates the processing if moire has not occurred.

As described above, once the LUTs having different resolutions are stored for a certain cloth, the process from the next time is the same as the step of preparing the LUTs for the resolutions in advance.
That is, when moiré occurs at a certain resolution for a certain cloth, a resolution that does not cause moiré can be selected. Since the creation of the LUT at that resolution has been completed in advance, the error diffusion input data is changed at the time of printing, and an image without moiré is printed.

This printing method can be used in exactly the same way with the dither method. However, the dither method is superior in terms of image processing speed, but a periodic method may occur, and the error diffusion method is preferable.

The process of step A in FIG. 2 may be performed when the resolution is changed, or may be performed in advance. Table 1 shows advantages and disadvantages of creating an LUT when changing the resolution and creating the LUT in advance.

[Table 1]

Next, a more efficient moiré eliminating method will be described. In general, when the medium performance changes (for example, when the cloth or the pretreatment agent applied to the cloth is changed), the color conversion software causes a phenomenon in which the color changes due to the change. That is, the color reproducibility deteriorates. In order to avoid such a problem, it is possible to prevent deterioration of the changed medium by changing only the LUT portion of the color conversion software. Therefore, it is preferable to create an LUT for each medium (fabric).

In the above-described method, an LUT corresponding to the resolution must be created for each cloth, and the error diffusion input data must be changed, which requires enormous labor. On the other hand, according to the study of the present inventors, it was found that the weave of the cloth and the thickness of the yarn greatly affected the color development state. Turned out to be good. In other words, it turned out that it is not necessary to change the LUT for each fabric. This indicates that LUTs should be created for various resolutions in advance.

The method of preparing in advance for various resolutions involves selecting similar fabrics. The weaving is specified by the number per unit mm, ± 30% of the standard
Those within can be seen as similar cloths. The weaving method is roughly divided into plain weave, oblique weave, satin weave, and others. If it is classified finely, the oblique weave has one-sided oblique and both-sided oblique, but if these are also broadly classified,
Good looking with similar cloth.

Regarding the thickness of the yarn, if it is within ± 30%, it can be regarded as similar. Furthermore, if the number of yarns constituting the yarn is ± 20%, it can be regarded as similar. In this manner, one representative example of similar fabric is selected.

Next, gradation curve change data is created for each resolution. The method of creating such change data is as described above. In addition, a color combination patch is created by using the gradation-corrected data at any one of the selectable resolutions, and an LUT is created. For other resolutions, an LUT is created by predicting the color of the color combination in calculation based on the gradation curve change data. In this way, if a LUT is created in advance for a representative fabric, the customer can newly create an LUT for a similar fabric.
, It is possible to obtain an image having substantially the same color and no moiré by changing the resolution.

(Embodiment 2) In the case of a cloth having a large amount of ink absorption such as a towel or a moquette, the following processing is performed. The customer prints on a towel, for example,
After coloring, washing and drying (hereinafter referred to as post-treatment), color density and bleeding are confirmed. Here, when the color density becomes insufficient or when bleeding occurs, the resolution is changed. Hereinafter, the above-described problem can be solved by performing printing at a desired resolution through the same steps as those described in the above-described first embodiment.

(Example 3) The present inventors have found that, in an ink jet printer for textile printing, a predetermined range in which the resolution can be changed to prevent moire is determined by the following method. For example, a dot diameter that can be formed by a head mounted on an ink jet printer for textile printing is 0.07.
In the case of 0 mm, its reciprocal (14.28) × √2 = 20
(Number of dots / mm: hereinafter referred to as dpm) is the minimum resolution that can be changed. If the minimum resolution is smaller than this, problems such as white streaks occur.

On the other hand, the maximum resolution is determined by the maximum color density L value regardless of the dot diameter. L here
The value is a perceived chromaticity index defined in the CIE1976 (L, a, b) space. FIG. 3 shows dpm on the horizontal axis.
(Resolution) is a graph showing the L value on the vertical axis. It can be seen that as the dpm increases, the L value decreases and the color density increases. The present inventors have found that the difference in color density disappears with an increase in dpm, and that the bleeding due to this disappears. Table 2 shows the results showing the change in color density and the degree of bleeding for a typical weave.
In other words, it has been found that when the variation of the L value is 1 or less, the ink absorption amount of the fabric is almost limited, and a new bleeding problem is caused. The maximum resolution in this table can be determined to be 19. As is clear from Table 2, the maximum resolution varies somewhat depending on the fabric to be printed,
It can be seen that an inkjet printer for textile printing is sufficient if it has a resolution twice the minimum resolution.

[Table 2]

After the resolution range is specified in this way,
The customer can freely select within a range of resolution by printing a thin line image or a picture. In the case of a thin line image, it is preferable to select the minimum resolution, and in the case of a picture, it is preferable to select the maximum resolution. At first glance, it is better to print the fine line image at the maximum resolution, but in practice, the variable range of this resolution is a method that focuses on the color density of the print, and the fine line image is printed at the maximum resolution. As a result, the line width may be too large to be suitable.

(Embodiment 4) Table 3 shows the relationship between dot diameter and resolution when a plurality of ink drops are ejected from the head in the same pixel in an ink jet printer for textile printing.

[Table 3]

According to this table, when the dot diameter is variable, the minimum resolution is 17 dpm and the maximum resolution is 3 dpm.
7dpm. Generally, if the drop is variable,
The resolution is constant and the resolution is determined by the minimum resolution. The portion where the drop is small is used as the area gradation.

According to this embodiment, the resolution is set to 17 dpm to
It can be selected in the range of 37 dpm. The customer selects 17 dpm for the fine line image and 37 for the picture.
It is good to select dpm. The reason is the same as the reason described in the third embodiment. Even if the drop is variable, the number of drops is automatically determined by the input data of the color to be printed. That is, in general, dark data is 3
You will draw with a drop.

As an application of this embodiment, in order to solve the above-mentioned problem, the resolution can be used variably, so it is better to set a specific resolution for each number of drops. In other words, changing the dot diameter according to the number of drops means changing the resolution in consideration of the fluctuation value of the L value. In the case of the present embodiment, the resolution is 37 dpm, 25
This means that three resolution choices, dpm and 19 dpm, can be made. The important thing is that at least the highest resolution can be selected. So in this case,
It is sufficient that 37 dpm can be selected. In this way, by associating the number of drops with the resolution, for example, 37 dpm for the thin line image can be selected. In the case of a picture, it may be arbitrarily selected from within the variable resolution range. In the case of a thin line image, a problem of roughness occurs because the drop diameter is constant. In this case,
It is preferable to print with two types of ink, dark and light.

(Embodiment 5) An ink jet printer for textile printing with variable resolution is provided with an encoder in the main scanning direction, and controls a discharge timing by dividing a signal read from a scale of the encoder. dpm can be determined. FIG. 4 is a diagram schematically showing such a configuration.

Method for increasing the resolution: The head (not shown) has the scale (p1,
When the sensor S reads (p2, p3,...), a drop emission is performed. First, perform an empty reading. More specifically, when the pitch of the scale of the encoder E is 12 dpm, after reaching a constant speed, the sensor S sequentially reads signals from the scales p1, p2,. At this time, the time when the clock is simultaneously raised and the scale p1 is read is defined as t1, and the time when the scale p2 is similarly read is defined as t2. Hereinafter, the time t3 of the scale p3 sequentially
As time is read. For example, when it is desired to double the resolution, (t2-t1) / 2, (t3-t2)
/ 2, (t4-t3) / 2 are calculated in advance. Further, when the scale p1 is read, and (t2-t
The ejection control of the ink drop is performed, for example, when the time of 1) / 2 has passed and when the scale p2 is read. As a result, emission control can be performed with half the scale of the encoder, and the resolution dpm is doubled.

The sub-scanning direction is controlled by sending a signal corresponding to a feed amount to a DC motor with a medium feeder encoder. In this case, it is possible to increase the gear ratio and adjust the fine medium feeding amount. For example, if the feeding is 50 μm, the resolution can be set to 20 dpm, and if the feeding is 83 μm, the resolution can be 2 d.
pm. However, a change in dpm in the main scanning direction does not have a significant effect on the printing speed, whereas a change in dpm in the sub-scanning direction changes the number of scans and affects printing time. Therefore, it can be said that it is desirable to change dpm in the main scanning direction at a possible level.

Although the present invention has been described with reference to the embodiments, it should be understood that the present invention should not be construed as being limited to the above-described embodiments, and that modifications and improvements can be made as appropriate. is there.

[0049]

According to the present invention, a method of controlling a printing ink jet printer and a printing ink jet printer for eliminating moiré and maintaining the color density even for a cloth having a large amount of ink absorption, such as a towel or a moquette, are provided. A printing method for a printer can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a mechanical configuration of a main part of an ink jet printer for textile printing according to an embodiment.

FIG. 2 is a flowchart for explaining a control method of the ink jet printer for textile printing.

FIG. 3 is a graph showing dpm (resolution) on the horizontal axis and L values on the vertical axis.

FIG. 4 is a schematic diagram showing a configuration in which the resolution in the ink jet printer for textile printing is variable.

[Explanation of symbols]

 2 Carriage 7 Encoder 10 Head 22 Inkjet printer for textile printing

 ──────────────────────────────────────────────────続 き The continuation of the front page F term (reference) 2C056 EA06 EC76 EC78 ED03 FB03

Claims (5)

[Claims] An ink drop ejection head movable in a main scanning direction and a sub scanning direction; and a control unit for changing image data into head driving data based on a look-up table and a pseudo gradation method. In the method of controlling an inkjet printer for textile printing, when moiré occurs in the textile printed by the inkjet printer for textile printing, a step of changing an adhesion position of the ink drop discharged from the head on the textile, A step of changing the look-up table according to the attachment position; and a step of changing input data used in the pseudo gradation method according to the changed attachment position. How to control the printer. 2. The method according to claim 1, wherein the pseudo gradation method can automatically select an error diffusion and / or dither method. 3. The control method for an ink jet printer for textile printing according to claim 1, wherein the same look-up table is applied to cloths of similar types. 4. An ink drop ejection head is provided,
In a printing method for an ink-jet printing printer capable of changing the resolution in at least one of the main scanning direction and the sub-scanning direction within a predetermined range, the minimum resolution is a reciprocal of a dot diameter ejected from the head and formed on a fabric × # 2, wherein the maximum resolution is when the difference between the L value of the maximum resolution and the lower resolution is at least L <1. 5. The resolution is changed by changing an attachment position of an ink drop ejected from the head on a cloth, and the minimum resolution is
The reciprocal of the dot diameter formed by the maximum number of ejected ink drops × √2, and the maximum resolution is the reciprocal of the dot diameter formed by one ink drop × √2, and 5. The printing method for an ink jet printer for textile printing according to claim 4, wherein the difference in L value at the resolution is at least L <2.