JP2022046083A - Method for detecting deviation amount between head units and ink-jet printer using the same - Google Patents

Abstract

To detect a deviation amount in a width direction in a connection portion by performing printing with a nozzle in an overlapping region viewed from a conveyance direction.SOLUTION: By deciding a segment chart in which the density in a chart TC for deviation amount detection becomes a peak, a deviation amount in a width direction Y from an ideal attachment state in a connection portion between one head unit 23a and another head unit 23b is obtained. Consequently, the printing quality in an ink-jet printer can be improved by adjusting the position in the width direction Y in the connection portion between the head units 23 on the basis of the deviation amount.SELECTED DRAWING: Figure 4

Description

INDUSTRIAL APPLICABILITY The present invention relates to a method for detecting a deviation amount of a head unit that detects a deviation amount in the width direction between head units when printing is performed by a print head configured by combining a plurality of head units in the width direction of a print medium. The present invention relates to an inkjet printing apparatus using the same.

Some inkjet printing devices print on a printing medium in the form of continuous paper. In such an inkjet printing apparatus, generally, a roll of continuous paper is unwound and conveyed in a predetermined conveying direction (also referred to as a sub-scanning direction). The print head is arranged with the long axis oriented in the width direction (also referred to as the main scanning direction) of the continuous paper orthogonal to the transport direction. The print head prints an image on the continuous paper by ejecting ink droplets toward the continuous paper being conveyed in the transport direction.

This print head may be configured by arranging a plurality of head units in which a plurality of nozzles for ejecting ink droplets are formed in the width direction of continuous paper. This is to reduce the manufacturing cost of the print head and to realize the ease of maintenance when the print head is damaged. In the configuration of the print head having such a configuration, there is one in which a plurality of head units are arranged in a staggered manner in a plan view. In addition, in the configuration of other print heads, a plurality of head units having a trapezoidal shape in a plan view are arranged with the upper bottom and the lower bottom facing in the transport direction, and the upper bottom is arranged for each adjacent head unit. And the lower base are alternately replaced, and the trapezoidal legs of each head unit are placed in parallel and close to each other in a straight line.

In a staggered print head, the nozzle positions in the width direction are generally overlapped when viewed from the transport direction. On the other hand, in a print head arranged in a straight line, the nozzle positions in the width direction are generally not overlapped when viewed from the transport direction. That is, in the linear arrangement, in one head unit and the other head unit adjacent thereto, among the plurality of nozzles, a plurality of nozzles arranged in overlapping regions when viewed from the transport direction are arranged. When viewed from the transport direction, they are installed so as to have a predetermined resolution at the time of printing by being positioned alternately without overlapping in the width direction. In the area where the head units do not overlap when viewed from the transport direction, the nozzles are arranged so that each head unit alone has a predetermined resolution at the time of printing.

When the print head is composed of a plurality of head units in this way, it is very difficult to align the print heads on a nozzle-by-nozzle basis during assembly or maintenance of the print heads. .. Therefore, the mounting position may vary at the portion where the head units are adjacent to each other in the width direction (hereinafter, referred to as a connecting portion). If such a variation occurs, the ink droplet position in the width direction will shift. Print quality deteriorates.

Therefore, a chart for detecting a specific deviation amount is printed while the continuous paper is conveyed to the print head, the deviation amount of the head unit is detected according to the result, and the position of the head unit is finely adjusted. ..

Conventionally, as a method of detecting the amount of deviation between head units of this type, the head on the downstream side is adjacent to the first line by the head unit on the upstream side in the width direction and separated from each other in the transport direction. When printing with the second line by the unit, following the first line, the second line after the first shift time so that the print positions match in the transport direction when separated by the design value in the transport direction. To print. Then, each combination of the first line and the second line is printed by shifting the position in the transport direction. Using the deviation amount detection chart printed in this way, the position in the transport direction between the head units is adjusted depending on which combination of the first line and the second line match in the transport direction. (See, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2019-181931 (Fig. 8)

However, in the case of the conventional example having such a configuration, there are the following problems.
That is, the conventional method detects the amount of deviation in the transport direction in the staggered arrangement. Therefore, there is a problem that the amount of deviation in the width direction in the linear arrangement cannot be detected.

Further, between head units that are staggered print heads and are adjacent to each other when viewed from the transport direction and are arranged so as to be offset in the width direction, nozzles in regions overlapping in the width direction when viewed from the transport direction are located in the width direction. Some of them are placed in overlapping positions. In the staggered print heads having such a configuration, line segments are printed in the transport direction from the nozzles in the overlapping areas of the head units which are adjacent to each other when viewed from the transport direction and are arranged so as to be offset in the width direction. Then, in terms of design, the amount of deviation in the width direction of each head unit can be easily calculated by obtaining the distance between the line segments printed by the nozzles arranged at the same position in the width direction. However, in the above-mentioned linearly arranged print heads, the nozzles are arranged at positions that do not overlap in the width direction by design in the overlapping area of the adjacent head units. Therefore, the above method cannot be applied to a print head arranged in a straight line.

The present invention has been made in view of such circumstances, and the deviation between the head units capable of detecting the deviation amount in the width direction at the joint portion by printing with the nozzles in the overlapping regions when viewed from the transport direction. It is an object of the present invention to provide a quantity detection method and an inkjet printing apparatus using the method.

The present invention has the following configuration in order to achieve such an object.
That is, the invention according to claim 1 is a head unit in an inkjet printing apparatus that performs printing by transporting a print medium in the transport direction to a print head in which a plurality of head units are arranged in the width direction of the print medium. In the method of detecting the amount of deviation between the head units, the plurality of head units are the one head unit and the other head unit arranged at the connecting portion adjacent to the one head unit in the width direction. In the overlapping region that overlaps when viewed from the transport direction, the plurality of nozzles of the one head unit and the plurality of nozzles of the other head unit are viewed from the transport direction. In the process of printing a deviation amount detection chart on the print medium using a group of nozzles arranged alternately in the width direction and located in the overlapping region, the deviation amount detection chart is described above. A plurality of first lines along the transport direction are printed by one head unit, and the plurality of first lines are printed at a first interval separated by a first number of nozzles. The other head unit prints a plurality of second lines along the transport direction, and the plurality of second lines are printed on the plurality of second lines when viewed from the transport direction. In the ideal mounting state in which the nozzle of the head unit and the nozzle of the other head unit are located at the center of the nozzle, the nozzle located at the center of the nozzles printed with the plurality of first line segments is used. A reference segment chart, which is printed at a second interval separated by a second number less than the number of 1, and is composed of the plurality of first line segments and the plurality of second line segments. The plurality of second lines are printed by the nozzles of the other head unit, which are located on one side of the center of the nozzles on which the plurality of first lines are printed. A one-sided segment chart printed at a position distant from the segment chart in the transport direction and composed of the plurality of first line segments and the plurality of second line segments, and the plurality of lines. The second line segment is printed by the nozzle of the other head unit located on the other side of the center of the nozzles on which the plurality of first line segments are printed, and is printed with respect to the reference segment chart. The other side segment chart printed at distant positions in the transport direction and composed of the plurality of first line segments and the plurality of second line segments. The concentration becomes the peak in the process of reading the deviation amount detection chart and the reference segment chart, the one-side segment chart, and the other-side segment chart of the read deviation amount detection chart. It is characterized by having a process of determining a segment chart.

[Action / Effect] According to the first aspect of the present invention, a deviation amount detection chart is printed on a printing medium in the printing process. Regarding the deviation amount detection chart read in the reading process, the segment chart having the peak concentration is determined from the reference segment chart, the one-side segment chart, and the other-side segment chart. Each segment chart is composed of a plurality of first line segments and a plurality of second line segments, and the distance between the first line segment and the second line segment is one head unit and the other. It moves according to the distance of the connecting part with the head unit. Therefore, when the reference segment chart has a peak density, one head unit and the other head unit are in an ideal mounting state. When the concentration peaks on the one-side segment chart, it means that one head unit is shifted to the other side or the other head unit is shifted to one side. When the concentration peaks on the other side segment chart, it means that one head unit is shifted to the other side or the other head unit is shifted to the other side. Therefore, by determining the segment chart in which the density peaks, it is possible to obtain the amount of deviation in the width direction from the ideal mounting state at the joint portion between one head unit and the other head unit. As a result, if the position in the width direction at the joint portion between the head units is adjusted based on this deviation amount, the print quality in the inkjet printing apparatus can be improved.

Further, in the present invention, it is preferable that the deviation amount detection chart includes a plurality of the reference segment chart, the one-side segment chart, and the other-side segment chart in the width direction (claim 2). ..

Since the number of segment charts is large in the width direction, it is possible to perform density averaging processing in the width direction. Therefore, even if there is an abnormality in one segment chart, its influence can be suppressed. Therefore, the amount of deviation can be accurately obtained.

Further, in the present invention, when the deviation amount detection chart includes a plurality of the one-side segment chart and the other-side segment chart in the transport direction, the one-side segment chart close to the reference segment chart is used. , The plurality of second line segments are composed of three lines, and the central second line segment has a printing rate of 100% at the same position in the width direction as the second line segment on one side of the reference segment chart. The second line segment located on both sides of the central second line segment is printed at a print rate of 50%, and the other side segment chart close to the reference segment chart is the plurality of second line segments. The two line segments are composed of three lines, and the second line segment in the center is printed at the same position in the width direction as the second line segment on the other side of the reference segment chart at a printing rate of 100%, and the center is said. It is preferable that the second line segments located on both sides of the second line segment are printed at a printing rate of 50% (claim 3).

In the overlapping region, the plurality of nozzles of one head unit and the plurality of nozzles of the other head unit are alternately arranged in the width direction when viewed from the transport direction. Therefore, the second line segment cannot be shifted by one nozzle in the width direction. Therefore, a plurality of second line segments are composed of three lines, the central second line segment has a printing rate of 100%, and the second line segments on both sides have a printing rate of 50%. As a result, the second line segment in the one-side segment chart and the other-side segment chart can be printed so as to be apparently offset by one nozzle in the width direction. Therefore, the minimum detection unit for the amount of deviation in the width direction can be one nozzle. As a result, the alignment between the head units can be performed precisely.

Further, in the present invention, it is preferable that the peak of the density is a high print density (claim 4).

The peak density may be high or low. By setting the case where the print density is high as the density peak, it is possible to easily visually determine one segment chart from each segment chart.

Further, in the present invention, it is preferable to include an adjustment process for adjusting the position in the width direction at the connecting portion between the units based on the selected segment chart, following the selection process (claimed). Item 5).

In the adjustment process, the position of the head unit is adjusted based on the amount of deviation. Therefore, the print quality in the inkjet printing apparatus can be improved.

The invention according to claim 6 is the above-mentioned inkjet printing apparatus for printing by transporting a print medium in the transport direction to a print head in which a plurality of head units are arranged in the width direction of the print medium. The plurality of head units are composed of one head unit and the other head unit arranged at a connecting portion adjacent to the one head unit in the width direction, and is composed of the other head unit in the transport direction. In the overlapping region that overlaps when viewed from the above, a plurality of nozzles of the one head unit and a plurality of nozzles of the other head unit are alternately arranged in the width direction when viewed from the transport direction. A control unit that operates the print head and prints a deviation amount detection chart on the print medium using a group of nozzles located in the overlapping region, and a control unit located downstream of the print head in the transport direction. A reading means for reading the deviation amount detection chart is provided, and the deviation amount detection chart is printed with a plurality of first line segments along the transport direction by the one head unit. The plurality of first lines are printed at the first interval separated by the first number of nozzles, and the other head unit prints the plurality of second lines along the transport direction. The printed plurality of second lines are in an ideal mounting state in which the nozzle of the other head unit is located at the center of the nozzle of the one head unit and the nozzle when viewed from the transport direction. In the above-mentioned plurality, the nozzles located at the center of the nozzles on which the plurality of first line segments are printed are printed at a second interval separated by a second number smaller than the first number. The reference segment chart composed of the first line segment of the book and the second line segment of the plurality of lines, and the second line segment of the plurality of lines are printed with the first line segment of the plurality of lines. The plurality of first lines are printed by the nozzles of the other head unit, which are located on one side of the center of the nozzles, and are printed at positions separated from the reference segment chart in the transport direction. The one-sided segment chart composed of the minute and the plurality of second lines and the plurality of second lines are from the center of the nozzles on which the plurality of first lines are printed. Is printed by the nozzle of the other head unit, which is biased toward the other side, and is printed at a position distant from the reference segment chart in the transport direction. A reference segment chart of a deviation amount detection chart read by the reading means, comprising a other side segment chart composed of the plurality of first line segments and the plurality of second line segments. Of the segment charts of the one-side segment chart and the other-side segment chart, the segment chart having the peak concentration is determined, and the position in the width direction at the connecting portion between the units is determined based on the determined segment chart. It is characterized by adjusting.

[Action / Effect] According to the sixth aspect of the present invention, the control unit operates the print head to print the deviation amount detection chart on the print medium. Regarding the deviation amount detection chart read by the reading means, the segment chart having the peak concentration is determined from the reference segment chart, the one-side segment chart, and the other-side segment chart. Each segment chart is composed of a plurality of first line segments and a plurality of second line segments, and the distance between the first line segment and the second line segment is one head unit and the other. It moves according to the distance of the connecting part with the head unit. Therefore, when the reference segment chart has a peak density, one head unit and the other head unit are in an ideal mounting state. When the concentration peaks on the one-side segment chart, it means that one head unit is shifted to the other side or the other head unit is shifted to one side. When the concentration peaks on the other side segment chart, it means that one head unit is shifted to the other side or the other head unit is shifted to the other side. Therefore, by determining the segment chart in which the density peaks, it is possible to obtain the amount of deviation in the width direction from the ideal mounting state at the joint portion between one head unit and the other head unit. As a result, if the position in the width direction at the joint portion between the head units is adjusted based on this deviation amount, the print quality in the inkjet printing apparatus can be improved.

According to the method for detecting the amount of deviation between head units according to the present invention, by determining the segment chart in which the concentration peaks, the width direction from the ideal mounting state at the joint portion between one head unit and the other head unit. You can get the amount of deviation to. As a result, if the position in the width direction at the joint portion between the head units is adjusted based on this deviation amount, the print quality in the inkjet printing apparatus can be improved.

It is a figure which shows the whole structure of the inkjet printing system which concerns on Example. It is a top view which shows the positional relationship between a print head and a plurality of head units and continuous paper. It is a partially enlarged view which shows the positional relationship between head units. It is a figure which shows an example of the chart for the deviation amount detection in the ideal mounting state. It is a figure which shows the deviation amount detection chart which shows the state which is shifted to the other side by two nozzles. It is a figure which shows the deviation amount detection chart which shows the state which is shifted to the other side by one nozzle. It is a flowchart which shows the adjustment process between head units. It is a figure which shows another example of the chart for the deviation amount detection in the ideal mounting state. It is a figure which shows the deviation amount detection chart which shows the state which is shifted to the other side by two nozzles. It is a figure which shows the deviation amount detection chart which shows the state which is shifted to the other side by one nozzle. It is another plan view which shows the positional relationship between a print head and a plurality of head units and continuous paper.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing an overall configuration of an inkjet printing system according to an embodiment. FIG. 2 is a plan view showing the positional relationship between the print head and the plurality of head units and the continuous paper. FIG. 3 is a partially enlarged view showing the positional relationship between the head units.

The inkjet printing system 1 according to this embodiment includes a paper feeding unit 3, an inkjet printing device 5, and a paper ejection unit 7.

The paper feed unit 3 rotatably holds, for example, a roll-shaped continuous paper WP around a horizontal axis. The paper feed unit 3 unwinds and supplies the continuous paper WP to the inkjet printing device 5. The paper ejection unit 7 winds up the continuous paper WP printed by the inkjet printing device 5 around the horizontal axis. Assuming that the supply side of the continuous paper WP is upstream and the discharge side of the continuous paper WP is downstream, the paper feed unit 3 is arranged on the upstream side of the inkjet printing device 5, and the paper discharge unit 7 is located on the inkjet printing device 5. It is located on the downstream side.

Here, the direction in which the continuous paper WP is conveyed from the upstream to the downstream is defined as the transfer direction X (secondary scanning direction). The width direction Y (main scanning direction) is defined as the front direction of the paper surface in FIG. 1, which is orthogonal to the transport direction X of the continuous paper WP in the horizontal direction. The direction orthogonal to the transport direction X and the width direction Y is defined as the height direction Z. In the following description, it will be referred to as the transport direction X or the X direction as appropriate.

The inkjet printing apparatus 5 is provided with a drive roller 9 for taking in continuous paper WP from the paper feed unit 3 on the upstream side. The continuous paper WP unwound from the paper feed unit 3 by the drive roller 9 is conveyed in the transfer direction X along the plurality of transfer rollers 11. A drive roller 13 is arranged between the most downstream transport roller 11 and the paper ejection unit 7. The drive roller 13 conveys the continuous paper WP conveyed on the transfer roller 11 in the transfer direction X, and sends out the continuous paper WP toward the paper ejection unit 7.

The continuous paper WP described above corresponds to the "printing medium" in the present invention.

The inkjet printing apparatus 5 is provided with a printing unit 15, a drying unit 17, and an inspection unit 19 between the drive roller 9 and the drive roller 13 in that order from the upstream side to the downstream side in the transport direction X. There is. The drying unit 17 dries the image printed by the printing unit 15. The inspection unit 19 reads the printed portion and inspects the printed surface for stains or omissions by image processing. In addition, the inspection unit 19 reads a chart for detecting the amount of deviation, which will be described later, and performs image processing for determining the amount of deviation.

The printing unit 13 is arranged at a distance in the height direction Z with respect to the transport path of the continuous paper WP by the transport roller 11. The printing unit 13 includes a printing head 21 that ejects ink droplets toward the continuous paper WP. In this embodiment, a configuration including four print heads 21 will be described as an example. Each print head 21 has a major axis in the width direction Y. Each print head 21 has a length exceeding the width of the continuous paper WP so that printing can be performed over the entire width of the continuous paper WP.

Here, each print head 21 is referred to as a print head 21a, a print head 21b, a print head 21c, and a print head 21d in this order from upstream to downstream in the transport direction X. In the present specification, when it is necessary to distinguish each print head 21, a reference numeral (a or the like) is added to the reference numeral 21, but when it is not necessary to distinguish between the reference numerals 21 and the print head 21 having only the reference numeral 21. do. The print heads 21a to 21d are configured to eject ink droplets of at least two colors and enable multicolor printing on continuous paper WP. Here, for example, the print head 21a ejects black (K) ink, the print head 21b ejects cyan (C) ink, the print head 21c ejects magenta (M) ink, and the print head 21d ejects yellow (yellow). Y) Ink is ejected. The print heads 21a to 21d are arranged apart from each other by a predetermined distance along the transport direction X.

In the following description, the print head 21a for ejecting black (K) ink will be described as an example, but the present invention can also be applied to print heads 21b to 21d of other colors.

The print head 21 includes a plurality of head units 23 in the width direction Y. The print head 21 has "connecting portions" between the two head units 23 at a plurality of locations. The head unit 23 includes a plurality of nozzles 25 for ejecting ink droplets. The plurality of nozzles 25 are arranged in the transport direction X and the width direction Y. Here, in order to facilitate the understanding of the invention, only two head units 23 will be described as an example. In the following description, of the head units 23 shown in FIG. 3, the head unit 23 arranged on the left side in the width direction Y is referred to as a head unit 23a, and is arranged adjacent to the head unit 23a, if necessary. The head unit 23 is referred to as a head unit 23b.

The head unit 23 includes a nozzle 25 for ejecting ink droplets. The head unit 23 is formed with a plurality of nozzles 25. The head unit 23 has, for example, a trapezoidal outer shape in a plan view. The print head 21 has a plurality of head units 23 arranged in a straight line in the width direction Y. In other words, the print head 21 is arranged in a straight line. Specifically, the print head 21 is configured by arranging a plurality of head units 23 having a trapezoidal shape in a posture in which an upper bottom and a lower bottom are oriented in the transport direction X. The plurality of head units 23 are arranged so that the upper bottom and the lower bottom are alternately interchanged for each of the adjacent head units 23. The plurality of head units 23 are arranged close to each other with the trapezoidal legs of each head unit 23 parallel to each other. At this time, the distance D1 between the head units 23, that is, the distance D1 between the trapezoidal legs between the head units 23 is determined by a predetermined resolution of the print head 21. However, this interval D1 will change depending on the mounting state of the head unit 23 deviating from the "ideal mounting state" when the design resolution can be obtained evenly over the width direction Y. That is, in the ideal mounting state, the interval D1 = id. On the other hand, when the distance between the head units 23 deviates from the ideal mounting state, the interval D1 = id ± a.

As shown in FIG. 3, the print head 21 is arranged so that the positions of the nozzles 25 in the width direction Y do not overlap when viewed from the transport direction X. Specifically, among the head unit 23a and the head unit 23b adjacent to each other in the width direction Y, in the overlapping region DA overlapping in the width direction Y when viewed from the transport direction X, the nozzle 25 of the head unit 23a and the head The nozzles 25 of the unit 23b are alternately arranged in the width direction Y. As a result, the print head 21 has a predetermined resolution in the overlapping area DA. In other words, in the ideal mounting state, the nozzles 25 of the head unit 23b are arranged at the center of the nozzles 25 of the head unit 23a. Further, the nozzles 25 of the head unit 23a are arranged at the center of the nozzles 25 of the head unit 23b. Although not shown, in the regions other than the overlapping region DA, the nozzles 25 are arranged at intervals narrower than the overlapping region DA in the width direction Y. As a result, a predetermined resolution is obtained over the entire area of the print head 25 in the width direction Y. Incidentally, when the resolution is 1200 dpi, the distance between the centers of the nozzle 25 of the head unit 23a and the nozzle 25 of the head unit 23b in the ideal mounting state is about 21 μm. When the distance between the head units 23 deviates from the ideal mounting state and the distance D1 = id ± a, the distance between the nozzles 25 deviates from the design value in the ideal state in the overlapping area DA, and the design in the overlapping area DA You will not be able to get the resolution.

The control unit 27 includes a CPU and a memory (not shown). The control unit 27 receives print data from an external computer (not shown). After converting the print data into print processing data, the control unit 27 operates the drive rollers 9 and 13 to convey the continuous paper WP in the transfer direction X. The control unit 27 ejects ink droplets from the print head 21 according to the print processing data. In this way, the control unit 27 causes the continuous paper WP to print an image based on the print data. The control unit 27 stores in advance the print processing data of the deviation amount detection chart TC as described below. The deviation amount detection chart TC is for detecting the deviation amount of the interval D1 in the width direction Y between the head units 23. When the operator of the inkjet printing system instructs to print the deviation amount detection chart TC, the control unit 27 reads out the print processing data of the deviation amount detection chart TC and operates the drive rollers 9, 13 and the print head 21. The chart for detecting the amount of deviation is printed on the continuous paper WP. Further, the control unit 27 receives information indicating the amount of deviation regarding the segment chart having the peak density after image processing by the inspection unit 19. Information indicating the received deviation amount is displayed on a display unit (not shown). The operator of the inkjet printing system 1 adjusts the position of the head unit 23 on the print head 21 by looking at this display.

Next, the deviation amount detection chart will be described with reference to FIGS. 4 to 6. Note that FIG. 4 is a diagram showing an example of a deviation amount detection chart in an ideal mounting state. FIG. 5 is a diagram showing a deviation amount detection chart showing a state in which the two nozzles are displaced to the other side by the amount of two nozzles. FIG. 6 is a diagram showing a deviation amount detection chart showing a state in which the other side is displaced by one nozzle. The nozzles 25 in FIGS. 4 to 6 are not included in the deviation amount detection chart TC, but are added for ease of understanding.

The deviation amount detection chart TC according to the embodiment includes a reference segment chart RC, a one-side segment chart SC1, and a other-side segment chart SC2.

For example, the reference segment chart RC shown in FIG. 4 is configured as follows.

In the reference segment chart RC, a plurality of first line segments L1 printed by the head unit 23a and a second line segment L2 printed by the head unit 23b are printed. The plurality of first line segments L1 are printed at the first interval S1 separated by the nozzles 25 of the first number LP (for example, 3). A plurality of a plurality of second line segments L2 are provided in an "ideal mounting state" in which the nozzle 25 of the head unit 23b is located at the center between the nozzles 25 of the head unit 23a when viewed from the transport direction X. The nozzle 25 located at the center of the nozzles 25 on which the first line segment L1 is printed is printed at the second interval S2 separated by the second number LP2 (for example, one) less than the first number LP2. Has been done.

The one-side segment chart SC1 is configured as follows.

The plurality of second line segments L2 in the one-side segment chart SC1 are on one side of the center of the nozzles 25 on which the plurality of first line segments L1 are printed (for example, to the right of the width direction Y in FIG. 4). ) Is printed by the nozzle 25 of the head unit 23b. Further, the plurality of second line segments L2 in the one-side segment chart SC1 are printed at positions separated from each other in the transport direction X with respect to the reference segment chart RC. The one-side segment chart SC1 is composed of the plurality of first line segments L1 and the plurality of second line segments L2.

The other side segment chart SC2 is configured as follows.

The plurality of second line segments L2 in the other side segment chart SC2 are on the other side of the center of the nozzles 25 on which the plurality of first line segments L1 are printed (for example, to the left of the width direction Y in FIG. 4). ) Is printed by the nozzle 25 of the head unit 23b. Further, the plurality of second line segments L2 in the other side segment chart SC2 are printed at positions separated from each other in the transport direction X with respect to the reference segment chart RC. In this embodiment, the reference segment chart RC is sandwiched and printed on the opposite side of the one-side segment chart SC1. The other side segment chart SC2 is composed of these plurality of first line segments L1 and a plurality of second line segments L2.

The deviation amount detection chart TC in this embodiment includes, for example, the above-mentioned reference segment chart RC, one-side segment chart SC1, and the other-side segment chart SC2 in the width direction Y.

The deviation amount detection chart TC shown in FIG. 4 described above is in an ideal mounting state, and the distance D1 = id between the head unit 23a and the head unit 23b. That is, the head unit 23a and the head unit 23b are attached to the print head 21 in a state where the resolution as designed can be obtained even in the overlapping region DA of the connecting portion.

In such a deviation amount detection chart TC, the reference segment chart RC has the highest concentration peak among the reference segment chart RC, the one-side segment chart SC1, and the other-side segment chart SC2. Specifically, the concentration of the reference segment chart RC is the highest. As shown in FIG. 4, in the one-side segment chart SC1 and the other-side segment chart SC2, two second line segments L2 are printed between the first line segment L1 and the other side segment chart SC2, respectively. The total area of the area where the background of the continuous paper WP is visible is the same for the reference segment chart RC, the one-side segment chart SC1, and the other-side segment chart SC2. In other words, there is a total non-printing area of the area not printed by the three nozzles 25 of the head unit 23a and the area not printed by the two nozzles 25 of the head unit 23b. However, in the reference segment chart RC, the non-printed area is finely divided by the first line segment L1. Therefore, the influence of the base of the continuous paper WP on the reference segment chart RC is smaller than that of the one-side segment chart SC1 and the other-side segment chart SC2. As a result, the reference segment chart RC has the highest print density visually. In other words, the density of the image by the first line segment L1 and the second line segment L2 is the highest. Therefore, as a result of printing the deviation amount detection chart TC, if there is a density peak due to printing on the reference segment chart RC, it can be determined that the ideal mounting state is such that the interval D1 = id.

Next, for example, a case where the head unit 23a and the head unit 23b deviate from the interval D1 = id at the connecting portion will be described.

For example, the head unit 23a is displaced to the other side (left in the width direction Y) by 25 minutes for two nozzles, or the head unit 23b is displaced to one side (right in the width direction Y) by 25 minutes for the two nozzles. A case where the deviation and the interval D1 are displaced from the id in the ideal mounting state and are mounted on the print head 21 will be described. The deviation amount detection chart TC in this case is shown in FIG. 5, for example.

In the deviation amount detection chart TC as described above, a concentration peak appears on the other side segment chart SC2. Therefore, it can be seen that the head unit 23a and the head unit 23b of the print head 21 are displaced in the width direction Y by 25 minutes from the ideal mounting state. From this, it can be seen that the position of the head unit 23a or the head unit 23b in the width direction Y needs to be adjusted by 25 minutes for the two nozzles in the direction opposite to the misalignment.

Next, for example, the head unit 23a shifts to the other side (left in the width direction Y) by one nozzle 25 minutes, or the head unit 23b shifts to one side (right in the width direction Y) by one nozzle 25 minutes. A case where the distance D1 is deviated from the id in the ideal mounting state and is mounted on the print head 21 will be described. The deviation amount detection chart TC in this case is shown in FIG. 6, for example.

In the deviation amount detection chart TC as described above, the concentration peaks appear on the reference segment chart RC and the other side segment chart SC2. Therefore, it can be seen that the head unit 23a and the head unit 23b of the print head 21 are displaced in the width direction Y by 25 minutes from the ideal mounting state. From this, it can be seen that the position of the head unit 23a or the head unit 23b in the width direction Y needs to be adjusted by 25 minutes for one nozzle in the direction opposite to the misalignment.

Next, the adjustment process of the interval D1 between the head units 23 by the above-mentioned deviation amount detection chart TC will be described. This adjustment process is performed, for example, by the procedure shown in FIG. 7. FIG. 7 is a flowchart showing an adjustment process between head units.

Step S1 (printing process)
The deviation amount detection chart TC is printed. The operator instructs the inkjet printing system 1 to start printing the deviation amount detection chart TC. In response to this instruction, the control unit 27 operates the print head 21 to print the above-mentioned deviation amount detection chart TC on the continuous paper WP.

Step S2 (reading process)
The control unit 27 operates the inspection unit 19 to read the printed deviation amount detection chart TC.

Step S3
The inspection unit 19 performs image processing on the read deviation amount detection chart TC.

Step S4 (decision process)
The inspection unit 19 determines which of the segment charts constituting the deviation amount detection chart TC the concentration peak is located. Based on the determination, the inspection unit 19 outputs the deviation amount as information to the control unit 27 together with the deviation direction on one side or the other side. The control unit 27 displays the information on a display unit (not shown).

Step S5 (adjustment process)
The operator of the inkjet printing system 1 adjusts the position of the head unit 23 in the print head 21 in the width direction by the distance between the nozzles 25 based on the information displayed on the display unit (not shown).

According to this embodiment, by determining the segment chart in which the concentration of the deviation amount detection chart TC is the peak, the width from the ideal mounting state at the joint portion between the one head unit 23a and the other head unit 23b. The amount of deviation in the direction Y can be obtained. As a result, if the position in the width direction Y at the connecting portion between the head units 23 is adjusted based on this deviation amount, the print quality in the inkjet printing apparatus 5 can be improved.

Further, the above-mentioned deviation amount detection chart TC is configured to include eight reference segment charts RC, one side segment chart SC1 and the other side segment chart SC2 in the width direction Y. Therefore, since the number of segment charts is large in the width direction Y, it is possible to perform a density averaging process in the width direction Y. Therefore, even if there is an abnormality in one segment chart, its influence can be suppressed. Therefore, even if the nozzle 25 has a problem such as clogging, the amount of deviation can be accurately obtained.

In the deviation amount detection chart TC in the above-described embodiment, the concentration difference between the reference segment chart RC and the other side segment chart SC2 is small depending on how the head unit 23 is displaced, and either or both. It may be difficult to determine if there is a concentration peak in. In that case, it is preferable to use the chart TCa for detecting the amount of deviation as shown below.

Here, reference is made to FIGS. 8 to 10. FIG. 8 is a diagram showing another example of the deviation amount detection chart in the ideal mounting state. FIG. 9 is a diagram showing a deviation amount detection chart showing a state in which the two nozzles are displaced to the other side by the amount of two nozzles. FIG. 10 is a diagram showing a deviation amount detection chart showing a state in which the other side is displaced by one nozzle.

In this deviation amount detection chart TCa, a one-side segment chart SC3 and a other-side segment chart SC4 are added as compared with the deviation amount detection chart TC described in FIG. 4 described above. In other words, the deviation amount detection chart TCa includes two segment charts (one-side segment charts SC1 and SC3 and the other-side segment charts SC2 and SC4) on one side and the other side in the transport direction X, respectively. Specifically, the one-sided segment chart SC3 is added between the reference segment chart RC and the one-sided segment chart SC1 in the transport direction X. Further, the other side segment chart SC4 is added between the reference segment chart RC and the other side segment chart SC2 in the transport direction X.

The added one-sided segment chart SC3, that is, the one-sided segment chart SC3 close to the reference segment chart RC, has three second line segments L2. The second line segment L2 in the center is printed at the same position in the width direction Y as the second line segment L2 on one side of the reference segment chart RC at a printing rate of 100%. The two second line segments L2 located on both sides of the central second line segment L2 in the width direction Y are printed at a printing rate of 50%. The printing rate of 50% may be realized, for example, by intermittently ejecting ink droplets in the transport direction X and using a line segment consisting of a dotted line instead of a continuous line segment.

The added other side segment chart SC4, that is, the other side segment chart SC4 close to the reference segment chart RC, has three second line segments L2. The second line segment L2 in the center is printed at the same position as the second line segment L2 on the other side of the reference segment chart RC in the width direction Y at a printing rate of 100%. The second line segment L2 located on both sides in the width direction Y with respect to the central second line segment L2 is printed at a printing rate of 50%.

In such a deviation amount detection chart TCa, the reference segment chart RC visually has the highest print density. The print density decreases in the order of the one-side segment chart SC3 and the other-side segment chart SC4, and the one-side segment chart SC1 and the other-side segment chart SC2. Therefore, as a result of printing the deviation amount detection chart TCa, if there is a density peak due to printing on the reference segment chart RC, it can be determined that the ideal mounting state is such that the interval D1 = id.

Next, for example, a case where the head unit 23a and the head unit 23b deviate from the interval D1 = id at the connecting portion will be described.

For example, the head unit 23a is displaced to the other side (left in the width direction Y) by 25 minutes for two nozzles, or the head unit 23b is displaced to one side (right in the width direction Y) by 25 minutes for the two nozzles. A case where the deviation and the interval D1 are displaced from the id in the ideal mounting state and are mounted on the print head 21 will be described. The deviation amount detection chart TCa in this case is as shown in FIG. 9, for example.

In the deviation amount detection chart TCA as described above, a concentration peak appears on the other side segment chart SC2 in the same manner as the deviation amount detection chart TC in FIG. 5 described above. Therefore, it can be seen that the head unit 23a and the head unit 23b of the print head 21 are displaced in the width direction Y by 25 minutes from the ideal mounting state. From this, it can be seen that the position of the head unit 23a or the head unit 23b in the width direction Y should be adjusted in the direction opposite to the misalignment. In FIG. 9, in the other side segment chart SC4, the base of the continuous paper WP is exposed by four nozzles 25, and in the other side segment chart SC2, the base of the continuous paper WP is exposed by five nozzles 25. There is. As a result, the print density of the other segment chart SC4 seems to be higher. However, in the other side segment chart SC4, since the two lines of the second line segment L2 have a print density of 50%, the print density of the other side segment chart SC2 is higher.

Next, for example, the head unit 23a shifts to the other side (left in the width direction Y) by one nozzle 25 minutes, or the head unit 23b shifts to one side (right in the width direction Y) by one nozzle 25 minutes. A case where the distance D1 is deviated from the id in the ideal mounting state and is mounted on the print head 21 will be described. The deviation amount detection chart TCa in this case is shown in FIG. 10, for example.

In the deviation amount detection chart TCa as described above, a concentration peak appears on the other side segment chart SC4. Therefore, it can be seen that the head unit 23a and the head unit 23b of the print head 21 are displaced in the width direction Y by 25 minutes from the ideal mounting state. From this, it can be seen that the position of the head unit 23a or the head unit 23b in the width direction Y should be adjusted in the direction opposite to the misalignment. In FIG. 10, in the other side segment chart SC4, the base of the continuous paper WP is exposed by four nozzles 25, and in the other side segment chart SC2, the base of the continuous paper WP is exposed by five nozzles 25. There is. Further, in the other side segment chart SC4, the base of the continuous paper WP is divided in the width direction Y for each region corresponding to one nozzle 25. Therefore, the print density of the other side segment chart SC4 is higher than that of the other side segment chart SC2 even if the two lines of the second line segment L2 have a print density of 50%.

In the deviation amount detection chart TCa as described above, the concentration peak appears only in the other side segment chart SC4. Therefore, it can be seen that the head unit 23a and the head unit 23b of the print head 21 are displaced in the width direction Y by 25 minutes from the ideal mounting state. From this, it can be seen that the position of the head unit 23a or the head unit 23b in the width direction Y should be adjusted in the direction opposite to the misalignment.

The deviation amount detection chart TCa configured in this way apparently deviates the second line segment L2 in the one-side segment chart SC3 and the other-side segment chart SC4 by one nozzle 25 in the width direction Y. Can be printed on. Therefore, the minimum detection unit for the amount of deviation in the width direction Y can be one nozzle for 25 minutes. As a result, the positioning between the head units 23 can be performed precisely.

The present invention is not limited to the above embodiment, and can be modified as follows.

(1) In the above-described embodiment, as shown in FIG. 2, a case where a plurality of head units 23 constituting the print head 21 are trapezoidal in a plan view has been described as an example. However, the present invention is not limited to such a shape. For example, it may have a shape as shown in FIG.

That is, the head unit 23 may have a parallel quadrilateral shape in a plan view. Even with such a head unit 23, the amount of deviation can be obtained by printing the above-mentioned charts TC and TCa for detecting the amount of deviation. When the head unit 23 having such a parallel four-sided shape is also arranged in a straight line on the print head 21, the positions of the nozzles 25 in the width direction Y do not overlap when viewed from the transport direction X.

(2) In the above-described embodiment, the deviation amount detection charts TC and TCa are configured to include eight segment charts in the width direction Y. However, the present invention is not limited to such a form. That is, the configuration may include one segment chart in the width direction Y. Further, 9 or more segment charts may be included in the width direction Y.

(3) In the above-described embodiment, a part of the second line segment L2 in the deviation amount detection chart TCa has a printing rate of 50%. However, the present invention is not limited to such a form. That is, the printing rate of a part of the second line segment L2 may be lower than the printing rate of the second line segment L2 in the center.

(4) In the above-described embodiment, it is assumed that the print density is high at the peak density. However, in the present invention, the peak density may be low in print density. For example, the above-mentioned continuous paper WP having a black base is used, and white ink is ejected to print a chart TC for detecting the amount of deviation. In the chart TC for detecting the amount of deviation printed in this way, the reference segment chart RC has the lowest print density in the ideal mounting state. Therefore, even if a segment chart having a low print density is determined as the peak density, the above-mentioned deviation amount can be obtained.

(5) In the above-described embodiment, in the deviation amount detection charts TC and TCa, one-sided segment charts SC1 and SC3 and the other-sided segment charts SC2 and SC4 are located on the upstream side and the downstream side in the transport direction X of the reference segment chart RC. And are arranged. However, the present invention is not limited to such an arrangement. That is, the reference segment chart RC is arranged at the end of the upstream side or the downstream side in the transport direction X, and the one-side segment charts SC1 and SC3 and the other-side segment charts SC2 and SC4 are arranged in order on the downstream side or the upstream side thereof. You may do it.

(6) In the above-described embodiment, continuous paper WP is taken as an example as the printing medium. However, the present invention is not limited to continuous paper WP. For example, as the printing medium, even a sheet paper or a flexible wrapping film can be applied to the present invention.

(7) In the above-described embodiment, the inkjet printing apparatus 5 in which four print heads 21 are arranged has been described as an example. However, the present invention is not limited to such a configuration. For example, the present invention can be applied if one print head 21 is provided.

(8) In the above-mentioned embodiment, an example in which a continuous line segment is used as a segment chart is given. However, the present invention is not limited to continuous line segments. For example, if the conditions are the same for the reference segment chart, the one-side segment chart, and the other-side segment chart, the present invention can be applied even when the vertical line of the segment chart is changed to a broken line.

As described above, the present invention is suitable for a method for detecting the amount of deviation between head units and an inkjet printing apparatus using the method.

1 ... Inkjet printing system 3 ... Feeding unit 5 ... Inkjet printing device 7 ... Paper ejection unit X ... Transport direction Y ... Width direction Z ... Height direction 9, 13 ... Drive roller 11 ... Transport roller 15 ... Printing unit 17 ... Drying Unit 19 ... Inspection unit 21 (21a, 21b, 21c, 21d) ... Print head 23 (23a, 23b) ... Head unit 25 ... Nozzle 27 ... Control unit TC ... Misalignment detection chart RC ... Reference segment chart SC1, SC3 ... One side segment chart SC2, SC4 ... The other side segment chart L1 ... First line segment S1 ... First interval L2 ... Second line segment S2 ... Second interval

Claims (9)

In a method for detecting a deviation amount between head units in an inkjet printing apparatus that prints by transporting a print medium in the transport direction to a print head in which a plurality of head units are arranged in the width direction of the print medium.
The plurality of head units are composed of one head unit and the other head unit arranged at a connecting portion adjacent to the one head unit in the width direction. In the overlapping region that overlaps when viewed from the direction, the plurality of nozzles of the one head unit and the plurality of nozzles of the other head unit are alternately arranged in the width direction when viewed from the transport direction. This is a process of printing a deviation amount detection chart on the print medium using the nozzle group located in the overlapping area.
The deviation amount detection chart is
A plurality of first line segments along the transport direction are printed by the one head unit, and the plurality of first line segments are printed at a first interval separated by a first number of nozzles. Has been
A plurality of second line segments along the transport direction are printed by the other head unit, and the plurality of second line segments are printed on the one head unit when viewed from the transport direction. In the ideal mounting state in which the nozzle of the other head unit is located at the center of the nozzle and the nozzle, the first number is due to the nozzle located at the center of the nozzles printed with the plurality of first line segments. A reference segment chart, which is printed at a second interval separated by a smaller second number and is composed of the plurality of first line segments and the plurality of second line segments.
The plurality of second line segments are printed by the nozzles of the other head unit located on one side of the center of the nozzles on which the plurality of first line segments are printed, and the reference segment is printed. A one-sided segment chart printed at a position separated from the chart in the transport direction and composed of the plurality of first line segments and the plurality of second line segments.
The plurality of second line segments are printed by the nozzles of the other head unit located on the other side of the center of the nozzles on which the plurality of first line segments are printed, and the reference segment is printed. The other side segment chart, which is printed at a position separated from the chart in the transport direction and is composed of the plurality of first line segments and the plurality of second line segments, is provided.
The process of reading the deviation amount detection chart and
The process of determining the segment chart having the peak concentration among the reference segment chart, the one-side segment chart, and the other-side segment chart of the read deviation amount detection chart, and the process of determining the segment chart.
A method for detecting the amount of deviation between head units, which comprises. In the method for detecting the amount of deviation between head units according to claim 1,
The deviation amount detection chart is a method for detecting a deviation amount between head units, which comprises a plurality of the reference segment chart, the one-side segment chart, and the other-side segment chart in the width direction. In the method for detecting the amount of deviation between head units according to claim 1 or 2.
When the deviation amount detection chart includes a plurality of the one-side segment chart and the other-side segment chart in the transport direction, respectively.
In the one-sided segment chart close to the reference segment chart, the plurality of second line segments are composed of three lines, and the second line segment in the center is the second line segment on one side of the reference segment chart. The second line segment located on both sides of the second line segment in the center is printed at the same position in the width direction at a printing rate of 100%, and the second line segment is printed at a printing rate of 50%.
In the other side segment chart close to the reference segment chart, the plurality of second line segments are composed of three lines, and the second line segment in the center is the second line segment on the other side of the reference segment chart. It is characterized in that it is printed at the same position in the width direction at a printing rate of 100%, and the second line segments located on both sides of the central second line segment are printed at a printing rate of 50%. A method for detecting the amount of deviation between head units. In the method for detecting the amount of deviation between head units according to any one of claims 1 to 3.
The peak of the density is a method for detecting a deviation amount between head units, which is characterized in that the print density is high. In the method for detecting the amount of deviation between head units according to any one of claims 1 to 4.
Following the selection process, the amount of deviation between the head units comprises an adjustment process for adjusting the position in the width direction at the connecting portion between the units based on the selected segment chart. Detection method. In an inkjet printing apparatus that prints by transporting a print medium in the transport direction to a print head in which a plurality of head units are arranged in the width direction of the print medium.
The plurality of head units are composed of one head unit and the other head unit arranged at a connecting portion adjacent to the one head unit in the width direction. In the overlapping region that overlaps when viewed from the direction, the plurality of nozzles of the one head unit and the plurality of nozzles of the other head unit are alternately arranged in the width direction when viewed from the transport direction. And
A control unit that operates the print head and prints a deviation amount detection chart on the print medium using a group of nozzles located in the overlapping region.
A reading means arranged on the downstream side of the print head in the transport direction and reading the deviation amount detection chart.
Equipped with
The deviation amount detection chart is
A plurality of first line segments along the transport direction are printed by the one head unit, and the plurality of first line segments are printed at a first interval separated by a first number of nozzles. Has been
A plurality of second line segments along the transport direction are printed by the other head unit, and the plurality of second line segments are printed on the one head unit when viewed from the transport direction. In the ideal mounting state in which the nozzle of the other head unit is located at the center of the nozzle and the nozzle, the first number is due to the nozzle located at the center of the nozzles printed with the plurality of first line segments. A reference segment chart, which is printed at a second interval separated by a smaller second number and is composed of the plurality of first line segments and the plurality of second line segments.
The plurality of second line segments are printed by the nozzles of the other head unit located on one side of the center of the nozzles on which the plurality of first line segments are printed, and the reference segment is printed. A one-sided segment chart printed at a position separated from the chart in the transport direction and composed of the plurality of first line segments and the plurality of second line segments.
The plurality of second line segments are printed by the nozzles of the other head unit located on the other side of the center of the nozzles on which the plurality of first line segments are printed, and the reference segment is printed. The other side segment chart, which is printed at a position separated from the chart in the transport direction and is composed of the plurality of first line segments and the plurality of second line segments, is provided.
Of the reference segment chart, the one-side segment chart, and the other-side segment chart of the deviation amount detection chart read by the reading means, the segment chart having the peak concentration is determined, and the determined segment chart is used. Based on this, an inkjet printing apparatus characterized in that the position in the width direction at the joint portion between the units is adjusted. In the inkjet printing apparatus according to claim 6,
The inkjet printing apparatus, wherein the deviation amount detection chart includes a plurality of the reference segment chart, the one-side segment chart, and the other-side segment chart in the width direction. In the inkjet printing apparatus according to claim 6 or 7.
When the deviation amount detection chart includes a plurality of the one-side segment chart and the other-side segment chart in the transport direction, respectively.
In the one-sided segment chart close to the reference segment chart, the plurality of second line segments are composed of three lines, and the second line segment in the center is the second line segment on one side of the reference segment chart. The second line segment located on both sides of the second line segment in the center is printed at the same position in the width direction at a printing rate of 100%, and the second line segment is printed at a printing rate of 50%.
In the other side segment chart close to the reference segment chart, the plurality of second line segments are composed of three lines, and the second line segment in the center is the second line segment on the other side of the reference segment chart. It is characterized in that it is printed at the same position in the width direction at a printing rate of 100%, and the second line segments located on both sides of the central second line segment are printed at a printing rate of 50%. Inkjet printing equipment. In the inkjet printing apparatus according to any one of claims 6 to 8.
The peak of the density is an inkjet printing apparatus characterized by a high print density.

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