JP2008080632A - Method for detecting size of droplet hitting point - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for detecting a size of a droplet hitting point which enables correct and simple calculation. <P>SOLUTION: The method includes a first image formation step of making ink liquid droplets ejected from an ejecting part and forming a first image which has droplet hitting points formed on a medium to be recorded, a second image formation step of making ink liquid droplets ejected from an ejecting part and forming a second image which has droplet hitting points formed on the medium, a droplet hitting point position detection step of reading the first image and detecting a droplet hitting point position formed by each ejecting part from the read first image, and a droplet hitting point size detection step of reading the second image and detecting the size of the droplet hitting point of each ejecting part on the basis of both image density information of the read second image and the droplet hitting point position. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a droplet ejection point size detection method for detecting the size of a droplet ejection point of an ink droplet ejected from each ejection unit of an image recording apparatus including a plurality of ejection units that eject ink droplets.

As a method for recording an image on a recording medium, there is an ink jet drawing method in which ink droplets are ejected in accordance with an image signal, landed on the recording medium, and an image is recorded.
As an image drawing apparatus using such an ink jet drawing method, an ejection unit (nozzle) for ejecting ink droplets is arranged in a line corresponding to the entire area of one side of a recording medium, and the recording medium is There is a full-line head type image drawing apparatus that records an image over the entire area of a recording medium by conveying in a direction orthogonal to the ejection unit.
The full line head type image drawing apparatus can draw an image on the entire area of the recording medium by transporting the recording medium without moving the ejection section, and can increase the recording speed.

  However, the line head type image drawing apparatus has a problem in that streaks and unevenness occur in an image recorded on a recording medium due to a manufacturing error such as a positional deviation of the ejection unit and a shape of the ejection unit.

  As a method for reducing such streaks and unevenness, Patent Document 1 detects an abnormal nozzle whose droplet flying direction is deviated, and a part of dots ejected from a nozzle adjacent to the abnormal nozzle has a size. An image forming apparatus is described in which large compensation dots are ejected, a gap formed between the dot rows is filled with the compensation dots, and streaks and unevenness due to the gaps are reduced.

Further, in Cited Document 2, as a dot shift detection method, an image acquisition step for acquiring an electronic image of a dot array formed on an object to be inspected, and image processing of the electronic image makes it possible to perform dot processing on the electronic image. A dot coordinate acquisition step for acquiring the X and Y coordinates of the center of each dot when the direction substantially parallel to the X-axis direction is the X-axis direction and the direction orthogonal to the X-axis direction is the Y-axis direction; A first reference line determination step for determining a first reference line by a least square method based on the X coordinate and the Y coordinate, and a distance between the first reference line and the center of each dot, thereby obtaining a Y-axis direction. A dot deviation detection method including a Y-axis direction deviation amount acquisition step for acquiring information regarding the positional deviation amount of each dot is described.
Furthermore, it also describes that the electronic image further includes dot area means for acquiring information related to the area of each dot by performing image processing on the electronic image. As a method for detecting the area of the dots, it is described that, for example, the length of the boundary line around each dot may be obtained without measuring the area of each dot itself.

Also, in cited document 3, there is a dot position detecting device for detecting the dot position of an ink jet printer, the dot position predicting means for predicting the dot position in an image formed by the ink jet printer, and the prediction by the dot position predicting means. A dot position calculating unit that calculates the position of the dot in the image based on the dot position that has been determined, and an ideal position where a dot is to be formed is calculated based on the dot position calculated by the dot position calculating unit. An ideal position calculating means; and a dot position deviation calculating means for calculating a deviation amount between the dot position calculated by the dot position calculating means and the ideal position of the dot calculated by the ideal position calculating means. A dot position detecting device is described.
In addition, the dot position prediction means creates a histogram of luminance values in the first direction in the image, obtains a first straight line passing through the minimum point of the histogram, and obtains a second orthogonal to the first direction. It is also possible to create a histogram of luminance values with respect to the direction, obtain a second straight line passing through the minimum point of the histogram, and predict that the intersection of the first straight line and the second straight line is a dot position. Are listed.
Further, it is described that the dot position calculation unit further calculates a dot radius in the image based on the dot position predicted by the dot position prediction unit.
Further, the ideal position calculation means approximates a straight line passing through the dots based on the dot position calculated by the dot position detection means, and calculates an ideal straight line having an average of the calculated straight line inclinations as an inclination. It is also described that an ideal line is calculated with an average of the calculated inclinations of the straight line as an inclination, and the calculated ideal line is set as the ideal position of the dot.

Japanese Patent Laid-Open No. 2005-70956 JP 2006-130383 A JP 2006-142546 A

As described above, Patent Documents 1 to 3 describe a method for detecting the position of the droplet ejection point formed by the ink droplets ejected from the ejection unit.
Here, the streak and unevenness of the image may occur depending on the size of the droplet ejection point formed by the ink droplets ejected from the ejection unit, for example, when the size of the landed ink droplet is different from the desired size. For this reason, in order to form an image free from streaks and unevenness, it is necessary to accurately detect the size of the droplet ejection point.
Here, cited documents 1 to 3 describe that the outer edge (outer shape, edge, boundary line) of each dot is detected and the size of the droplet ejection point is calculated. For example, cited document 3 describes detecting the outer edge of a dot using luminance.
Although it is possible to detect the size of the droplet ejection point by detecting the outer edge of the dot in this way, the size of the droplet ejection point formed by the ejection unit is accurately detected by detecting the outer shape of one dot. In order to do this, there is a problem that it is necessary to read dots with a high-quality image reading apparatus and accurately detect the outer edge of the dots.
There is also a problem that it is difficult to accurately detect the boundary line between one dot and the recording medium, that is, the outer edge of the dot.

In addition, for example, in an ink jet drawing apparatus that draws an image with a resolution of 300 dpi (dot per inch) to 650 dpi, the interval between the ink droplet ejection positions is 85 to 42.5 μm. That is, as the resolution of the ink jet drawing apparatus increases, the interval between the ink droplet ejection positions becomes shorter.
For this reason, in order to efficiently and accurately reduce streaks and unevenness, the positional deviation of the position where the ink droplet ejected from the ejection section lands (hereinafter also referred to as “droplet point”) is accurately detected. There is a need.

However, Patent Document 1 describes a method of reducing streaks and unevenness at the time of recording, but does not particularly describe a method of calculating a dot ejection point position shift.
In addition, in the detection method described in Patent Document 2, it is necessary to read dots with a high-resolution image reader and calculate the center position of the dots in order to accurately calculate the interval between droplet ejection points. There's a problem.
In addition, in the detection method described in Patent Document 2, it is difficult to determine the center of a dot if the dot adheres to an adjacent dot due to bleeding on the recording medium, and the interval between droplet ejection positions. There is also a problem that cannot be calculated accurately.
In addition, the dot position detection device described in Patent Document 3 also examines the histogram in two orthogonal directions, obtains a straight line from the minimum points of the histogram, and sets the calculated intersection of the straight lines as the position of the droplet ejection point. However, in order to accurately calculate the interval between the droplet ejection points, it is necessary to read the dots with a high-resolution image reader and calculate the center position of the dots. The deviation between the ideal position calculated by the dot position detection device of Patent Document 3 and the droplet ejection point position is an average dot position and the deviation, and the interval between droplet ejection points is calculated. Therefore, the droplet ejection point interval cannot be calculated.

In view of the above, an object of the present invention is to provide a droplet ejection point size detection method capable of solving the above-described problems based on the prior art and calculating the droplet ejection point size accurately (highly) and simply. It is in.
In addition to the above object, another object of the present invention is to provide a droplet ejection point size detection method that can accurately (highly) accurately calculate the interval between droplet ejection points and the displacement of the droplet ejection point position. is there.

  In order to solve the above-described problems, the present invention provides an ink droplet ejected from each ejection unit of a recording head in which a plurality of ejection units that eject ink droplets are arranged in a line and landed on a recording medium. A droplet ejection size detection method for detecting a droplet size, wherein a first image is formed by ejecting ink droplets from the ejection unit to form a first image in which droplet ejection points are formed on the recording medium. A step of forming, a second image forming step of forming a second image in which droplets are formed on the recording medium by discharging ink droplets from the discharge unit, and reading and reading the first image. A droplet ejection point position detecting step for detecting a droplet ejection point position formed by each of the ejection units from the first image, reading the second image, image density information of the read second image, and the droplet ejection point Based on the position of each droplet ejection point A droplet ejection point size detection step of detecting the size, there is provided a droplet deposition point size detection method for, comprising.

Here, it is preferable that the second image forming step forms a second image having an image area ratio of 40% to 60%.
In the second image forming step, the second image is formed on the same recording medium as the recording medium on which the first image is formed, that is, the recording medium on which the first image is formed. It is preferable to form the second image in another area.

  In the first image forming step, it is preferable that the droplet ejection point is formed in a size that does not contact the droplet ejection point adjacent to the width direction of the recording medium and the direction orthogonal to the width direction.

  In the first image forming step, a plurality of ink droplets are ejected from the ejection unit, and a plurality of droplet ejection points are formed for each ejection unit. An image reading step for reading the first image as a read image with a direction orthogonal to a direction substantially parallel to a direction in which a plurality of droplet ejection points formed by the section are arranged as a reference direction; and image processing of the read image A droplet ejection point position information calculating step for calculating, as droplet ejection point position information, one end position and the other end position in the reference direction of each droplet ejection point of the read image; A droplet ejection point position information classification step for classifying the droplet ejection point position information as droplet ejection point position classification information for each ejection unit that ejected each droplet ejection point, and one ejection based on the droplet ejection point position classification information Discharged from the section Approximate straight line calculation step for calculating an approximate straight line connecting one end position of a plurality of droplet ejection points and an approximate straight line connecting the other end position respectively for each of the ejection units, with the inclination of the approximate straight line being common. And a droplet ejection point position calculating step of calculating a droplet ejection point position of the ejection unit from the approximate line of one end position calculated for each ejection unit and the approximate line of the other end position. Is preferred.

Further, the droplet ejection point position detecting step further includes the droplet ejection point of the ejection unit and another ejection from the approximate straight line of one end position calculated for each ejection unit and the approximate straight line of the other end position. It is preferable to have a droplet ejection point interval calculating step for calculating an interval between the droplets and the droplet ejection point.
The approximate straight line is preferably calculated by a least square method.
Further, in the first image forming step, the rows of droplet ejection points formed on the recording medium are formed at different positions in a direction orthogonal to the arrangement direction of the ejection units according to the arrangement position of the ejection units. It is preferable.
In addition, the first image forming step includes ejecting ink droplets from every other ejection portion of the plurality of ejection portions to form a row of the droplet ejection points on the recording medium, and then remaining Preferably, ink droplets are ejected from the ejection section to form an array of droplet ejection points on the recording medium.

According to the present invention, the droplet ejection point position is detected from the first image, and the size (size) of each droplet ejection point is detected based on the image density and the droplet ejection point position detected from the second image. Thus, it is possible to easily detect the droplet ejection spot size with high accuracy.
Further, by calculating an approximate straight line at each end of the droplet ejection point of each ejection unit from a plurality of droplet ejection points for each ejection unit, and calculating the droplet ejection point position from this calculated approximate line, the droplet ejection point The position can be detected accurately (high accuracy), and the size of the droplet ejection point can be detected with higher accuracy.
Further, by calculating the droplet ejection point interval from the approximate straight line, the droplet ejection point interval and the deviation of the droplet ejection point position can be accurately and easily calculated. Further, by using a plurality of droplet ejection points for calculating the approximate straight line, even when the droplet ejection point is read at a low resolution, the positional deviation of the droplet ejection point can be accurately detected (highly accurate). .

  A droplet ejection point size detection method according to the present invention will be described in detail based on an embodiment shown in the accompanying drawings.

First, an example in which the droplet ejection spot size detection method of the present invention is used in a digital label printing apparatus using an ink jet drawing apparatus will be described.
1 is a schematic configuration diagram showing an example of a digital label printing apparatus 100, FIG. 2 is a longitudinal sectional view of a recording medium for label printing used in the digital label printing apparatus 100 shown in FIG. 1, and FIG. FIG. 4 is an enlarged schematic perspective view showing the drawing unit 112 of the digital label printing apparatus 100 shown in FIG. 1, and FIG. 4A is a front view showing an arrangement pattern of the ejection units 60 of the recording head 136K. 4B is an enlarged cross-sectional view illustrating one ejection unit 60 of the recording head 136K, and FIG. 5 is a schematic diagram illustrating a configuration of an ink supply system and a head peripheral portion in the inkjet drawing apparatus 100. 6A is a cross-sectional view showing a main part of a recording medium having an uneven surface, and FIG. 6B is a cross-sectional view showing a main part of the recording medium pressed without being smoothed. And FIG. 6C shows the smoothing. Is a cross-sectional view showing the main portion of the foil was the recording medium irregularities and smoothed by.

The digital label printing apparatus 100 of the present embodiment is an ultraviolet curable inkjet digital label printing apparatus using an ultraviolet curable ink that is an active energy (active light) curable ink, and has a foil stamping unit and is capable of foil stamp printing. It is a label printing device.
Here, foil press printing is a method of pressing a foil such as a gold foil, a silver foil, a color foil, etc. on a book cover or spine against a mating member with a heated letterpress to heat-press (foil press) the foil. Also called a hot stamp.
Further, as shown in FIG. 2, the recording medium P of the present embodiment has a two-sheet structure in which an adhesive sheet 180 having a back surface coated with an adhesive 180a is superposed on a release paper 182 as a mount.

  As shown in FIG. 1, the digital label printing apparatus 100 basically includes a transport unit 110, a drawing unit 112, a droplet ejection point detection unit 114, a smoothing unit 116, a foil pressing unit 118, and a label removing unit 120. And a control unit 121. The control unit 121 controls various operations of the transport unit 110, the drawing unit 112, the droplet ejection point detection unit 114, the smoothing unit 116, the foil pressing unit 118, and the label removing unit 120.

  Here, the transport unit 110 transports a continuous paper-like recording medium P for label printing (hereinafter referred to as “recording medium P”) in a certain direction (from left to right in FIG. 1). The drawing unit 112, the droplet ejection point detection unit 114, the smoothing unit 116, the foil pressing unit 118, and the label removal unit 120 are arranged in the order of the conveyance direction of the recording medium P, that is, from the upstream to the downstream direction. The part 114, the smoothing part 116, the foil pressing part 118, and the label removing part 120 are arranged in this order.

The conveyance unit 110 includes a supply roll 122, conveyance roller pairs 124, 126, 128, 130, and 132, and a product winding unit 134.
A continuous paper-like recording medium P for label printing is wound around the supply roll 122 in a roll shape. The conveyance roller pairs 124, 126, 128, 130, and 132 are driven to rotate by a conveyance motor (not shown), and the recording medium P is fed out from the supply roll 122 to draw the drawing unit 112, the droplet ejection point detection unit 114, and the smoothing unit 116. Then, the sheet is sequentially conveyed to the foil pressing unit 118 and the label removing unit 120.
The product take-up unit 134 is disposed on the most downstream side in the conveyance direction of the recording medium P, and is conveyed by the conveyance roll pairs 124, 126, 128, 130, 132, and the drawing unit 112, the droplet ejection point detection unit 114, and the smoothing. The recording medium P that has passed through the portion 116, the foil pressing portion 118, and the label removing portion 120 is taken up.

The drawing unit 112 includes a recording head unit 135, an ink storage / loading unit 137, and an ultraviolet irradiation unit 138.
The recording head unit 135 has recording heads (inkjet heads) 136Y, 136M, 136C, and 136K, and the position facing the transport path of the recording medium P, that is, the tip of the ejection unit that ejects ink droplets is the recording medium. It is arranged to face P.

The recording heads 136Y, 136M, 136C, and 136K are inkjet heads that discharge yellow (Y), magenta (M), cyan (C), and black (K) ink from the discharge unit, respectively. The recording head 136Y, the recording head 136M, the recording head 136C, and the recording head 136K are arranged in this order from the upstream to the downstream in the transport direction. The recording heads 136Y, 136M, 136C, and 136K are connected to the ink storage / loading unit 137 and the control unit 121.
As shown in FIG. 3, the recording heads 136Y, 136M, 136C, and 136K include a plurality of ejection units in a region where the width in the direction perpendicular to the transport direction of the recording medium P exceeds the maximum width of the recording medium P to be transported. This is a full-line type ink jet head in which (nozzles) are arranged in a line. The structure of the inkjet head will be described in detail later together with the relationship with the ink storage / loading unit 137.

As in this embodiment, the recording head is a full-line type, so that the recording medium P and the drawing unit 112 are relatively 1 in the direction (sub-scanning direction) orthogonal to the extending direction of the ejection unit of the recording head. The image can be recorded on the entire surface of the recording medium P by being moved once (that is, by one scanning). Thereby, it is possible to perform high-speed printing as compared with the shuttle type head in which the recording head reciprocates in the main scanning direction, and productivity can be improved.
Further, a color image can be formed on the recording medium P by ejecting the color inks from the recording heads 136Y, 136M, 136C, and 136K while transporting the recording medium P.

The ink storage / loading unit 137 includes an ink supply tank that stores ink of colors corresponding to the recording heads 136Y, 136M, 136C, and 136K.
As the ink supply tank, for example, a system that replenishes ink into a tank from a replenishing port (not shown) or a cartridge system that replaces the entire tank when the ink remaining amount is low can be used.
Each ink supply tank of the ink storage / loading unit 137 communicates with each recording head 136Y, 136M, 136C, 136K via a pipe line (not shown), and supplies ink to each recording head 136Y, 136M, 136C, 136K. To do.

  Next, the structure of the recording heads 136Y, 136M, 136C, and 136K will be described. Here, since the recording heads 136Y, 136M, 136C, and 136K have the same configuration except for the color of the ejected ink, the recording head 136K will be described below as a representative.

4A is a front view showing an arrangement pattern of the ejection portions 60 of the recording head 136K, and FIG. 4B is an enlarged cross-sectional view showing one ejection portion 60 of the recording head 136K.
As shown in FIG. 4A, in the recording head 136K, a plurality of ejection units 60 are arranged in a line at regular intervals.

  As shown in FIG. 4B, one ejection unit 60 includes an ink chamber unit 61 and an actuator 66. Further, the ink chamber unit 61 is connected to the common flow path 65. The common flow path 65 is connected to the ink chamber units 61 of the plurality of ejection units 60.

The ink chamber unit 61 has a nozzle 62, a pressure chamber 63, and a supply port 64.
The nozzle 62 is an opening for ejecting ink droplets, and has one end opened on a surface facing the recording medium P and the other end connected to the pressure chamber 63.
The pressure chamber 63 has a rectangular parallelepiped shape whose plane shape perpendicular to the direction in which the ink droplets are ejected, and both corners on the diagonal are connected to the nozzle 62 and the supply port 64.
The supply port 64 has one end connected to the pressure chamber 63 and the other end communicating with the common flow path 65.

The actuator 66 is disposed on a surface (top surface) opposite to the connection surface of the pressure chamber 63 with the nozzle 62 and the supply port 64, and includes a pressure plate 67 and an individual electrode 68.
The actuator 66 deforms the pressure plate 67 by applying a driving voltage to the individual electrode 68.

An ink discharge method of the discharge unit 60 will be described.
Ink is supplied from the common flow path 65 to the pressure chamber 63 and the nozzle 62 via the common port 64.
When a drive voltage is applied to the individual electrode 68 while the pressure chamber 63 and the nozzle 62 are filled with ink, the pressure plate 67 is deformed, the pressure chamber 63 is pressurized, and ink is ejected from the nozzle 62. The By driving the actuator 66 in this way, ink droplets can be ejected from the nozzle 62.
When ink is ejected, new ink is supplied from the common flow path 65 through the supply port 64 to the pressure chamber 63.

  In addition, the arrangement structure of the discharge part of this invention is not limited to the example of illustration. In this embodiment, a method of ejecting ink droplets by deformation of an actuator 66 typified by a piezo element (piezoelectric element) is adopted. However, the present invention is not limited to this, and a method of ejecting ink is particularly used. The present invention is not limited, and various methods such as a thermal jet method in which bubbles are generated by heating ink with a heating element such as a heater and ink droplets are ejected by the pressure can be applied instead of the piezo method.

Next, the relationship between the recording head unit 135 and the ink storage / loading unit 137 will be described in more detail.
FIG. 5 is a schematic diagram illustrating a configuration of an ink supply system and a head peripheral portion in the inkjet drawing apparatus 100. Since the relationship between the recording heads 136Y, 136M, 136C, and 136K and the ink storage / loading unit 137 is the same except for the type of ink, the recording head 136K and the ink storage / loading are hereinafter described. Only the relationship with the unit 137 will be described, and the description with respect to the relationship between the recording 136Y, 136M, and 136C and the ink storage / loading unit 137 will be omitted.

The ink supply tank 70 is a tank that stores a color corresponding to the recording head 136 </ b> K, that is, black ink, and is disposed inside the ink storage / loading unit 137. The recording head 136K and the ink supply tank 70 are connected by a supply pipe.
A filter 72 is provided in the middle of the flow path connecting the ink supply tank 70 and the recording head 136K to remove foreign substances and bubbles. The filter mesh size of the filter 72 is preferably equal to or smaller than the nozzle diameter (generally about 20 μm).

  A sub tank is preferably provided in the vicinity of the recording head 136K or integrally with the recording head 136K. By providing the sub tank, it is possible to obtain a damper effect that prevents fluctuations in the internal pressure of the head, and to improve refill.

  Further, as shown in FIG. 5, the digital label printing apparatus 100 includes a cap 74, a suction pump 77 and a collection tank 78 as means for preventing the nozzle 62 from drying or preventing an increase in ink viscosity near the nozzle, and a recording. A cleaning blade 76 is provided as a cleaning means for the nozzle surface of the head 136K, that is, the surface where the opening of the nozzle 62 is formed.

  The maintenance unit including the cap 74 and the cleaning blade 76 can be moved relative to the recording head 136K by a moving mechanism (not shown), and is moved from a predetermined retracted position to a maintenance position below the recording head 136K as necessary. .

The cap 74 is disposed at a position facing the recording head 136K in the maintenance position, and is supported so as to be movable up and down relatively with respect to the recording head unit 135 by a lifting mechanism (not shown).
The cap 74 is raised to a predetermined ascending position by an elevating mechanism (not shown) when the power is turned off or during printing standby, is in close contact with the recording head 136K, and covers the nozzle surface of the recording head 136K with the cap 74.
As described above, the cap 74 covers the nozzle surface of the recording head 136K and seals it, so that the ink in the nozzles is dried and fixed, and the ink solvent evaporates to increase the ink viscosity. Can be prevented.

Alternatively, the cap 74 may be attached to the recording head 136K at the time of maintenance or at regular intervals, and the actuator 66 may be driven to eject ink from the nozzles 62.
In the recording head 136K, when the specific nozzle 62 is used less frequently during drawing or standby, and ink is not ejected for a certain period of time, the ink solvent near the nozzle evaporates and the ink viscosity increases. As a result, the ink may not be ejected from the nozzle 62, but the ink is preliminarily ejected to the cap 74 (purge, idle ejection, spit) and the deteriorated ink in the nozzle 62 (near the nozzle whose viscosity has increased). Ink) can be discharged from the nozzle 62. Thereby, it is possible to prevent the nozzle 62 from being clogged with ink, and it is also possible to prevent the nozzle 62 from having a different ink viscosity and change in ejection characteristics. Thereby, ink droplets can be stably discharged.

The suction pump 77 has one end connected to the cap 74 and the other end connected to the recovery tank 78. The cap 74 is attached to the recording head 136K, and suction is performed by the suction pump 77 in a state where the cap 74 and the recording head 136K are in close contact with each other, whereby the ink in the nozzle 62 is sucked out. Further, the ink sucked by the suction pump 77 is sent to the collection tank 78.
As described above, by sucking ink by the suction pump 77, for example, bubbles are mixed into the ink (in the pressure chamber 63) in the recording head 136K, and the ink can be ejected from the nozzle even if the actuator 66 is operated. Even if it cannot, the ink in the pressure chamber 63 (ink mixed with bubbles) can be removed by suction by sucking the ink with the suction pump 77. That is, the ink droplets can be ejected.
The suction by the suction pump 77 is preferably performed in order to suck out the deteriorated ink whose viscosity has been increased (solidified) even when the ink is initially loaded into the head or when the ink is used after being stopped for a long time.
Further, since the suction by the suction pump 77 is performed on the entire ink in the pressure chamber 63, the amount of ink consumption increases. Accordingly, when the increase in the viscosity of the ink is small, it is preferable to discharge the ink droplets (preliminary discharge) onto the cap 74 described above.

The cleaning blade 76 is formed of an elastic member such as rubber, and is arranged in contact with the nozzle surface of the recording head 136K during maintenance. The cleaning blade 76 is connected to a blade moving mechanism (wiper) (not shown), and is slid on the nozzle surface by the blade moving mechanism. As the cleaning blade 76 slides on the nozzle surface, ink droplets and foreign matter adhering to the nozzle surface are wiped off. That is, the nozzle surface can be cleaned.
In addition, it is preferable to perform preliminary ejection in order to prevent foreign matter from being mixed into the nozzle 62 by the blade when the dirt on the ink ejection surface is cleaned by the blade mechanism.

Returning to FIG. 1, another part of the digital label printing apparatus 100 will be described.
The ultraviolet irradiation unit 138 is an active energy irradiation light source, and is arranged on the downstream side of each recording head 136Y, 136M, 136C, 136K corresponding to each recording head 136Y, 136M, 136C, 136K. As the ultraviolet irradiation unit 138, various ultraviolet light sources such as a metal halide lamp, a high-pressure mercury lamp, and a UVLED can be used.
The ultraviolet irradiating unit 138 passes the recording heads 136Y, 136M, 136C, and 136K, and irradiates the recording medium P on which the image is formed with ultraviolet rays. In other words, the ultraviolet irradiation unit 138 applies energy to the ink on the recording medium immediately after the ink ejected from the recording head and placed on the recording medium P is cured, and cures the ink on the recording medium P.

Here, the ultraviolet irradiation unit 138 has a position or configuration in which the emitted ultraviolet light is applied to the ink on the recording medium P and is not applied to the ink ejection ports of the recording heads 136Y, 136M, 136C, and 136K. It is preferable. In this way, by preventing the ink ejection port from being irradiated with ultraviolet rays, it is possible to prevent the ink from being cured at the ejection port.
Further, it is preferable to perform a light reflection preventing treatment (for example, a matte black treatment) on each part in the vicinity of the ultraviolet irradiation unit 138.

  The droplet ejection point detection unit 114 is disposed on the downstream side of the ultraviolet irradiation unit 138 corresponding to the recording head 136K in the conveyance path of the recording medium P so as to face the recording medium P. The droplet ejection point detection unit 114 includes an image sensor (line sensor or the like) for imaging the droplet ejection result of the drawing unit 112, and sends droplet ejection image data read by the image sensor to the control unit 121. More specifically, in the control unit 121, an arithmetic device (not shown) of the control unit 121 detects the droplet ejection point position and the droplet ejection point size from the image data sent from the droplet ejection point detection unit 114. The detection of the position of the droplet ejection point and the size of the droplet ejection point will be described in detail later.

  The droplet ejection point detection unit 114 of this embodiment includes a line sensor having a light receiving element array wider than the ink ejection width (image recording width) by the recording heads 136Y, 136M, 136C, and 136K. The line sensor includes an R sensor array in which photoelectric conversion elements (pixels) provided with a red (R) color filter are arranged in a line, a G sensor array provided with a green (G) color filter, And a color separation line CCD sensor including a B sensor array provided with a blue (B) color filter. Instead of the line sensor, an area sensor in which the light receiving elements are two-dimensionally arranged can be used.

  Next, the smoothing unit 116 is disposed on the downstream side of the drawing unit in the conveyance direction of the recording medium P, and is transparent on the surface of the recording medium P (ultraviolet in the present embodiment) curable liquid (hereinafter, “ The varnish coater 142, which is a transparent liquid supply means for supplying an “active energy curable transparent liquid” or simply “transparent liquid”), and a flat surface process for pressing and smoothing the foil supply range described later of the recording medium P. The pressure member 146 includes an ultraviolet irradiation unit 148 that is an active energy irradiation unit that irradiates and cures the transparent liquid with active energy.

The varnish coater 142 includes a pair of application rollers 144 and 145.
The coating rolls 144 and 145 have a transparent liquid attached (impregnated) on the surface, and are disposed at positions where the recording medium P conveyed by the conveying unit 110 is sandwiched. The application rolls 144 and 145 rotate in response to (synchronously with) the movement of the recording medium P while sandwiching the recording medium P, thereby passing through the drawing unit 112 and the recording medium on which an image is formed. A transparent liquid is applied to the surface of P (the surface on which the image is formed).

  Here, the transparent liquid applied by the varnish coater 142 is an active energy curable transparent liquid that can be cured by ultraviolet irradiation, and includes at least a polymerizable compound and a photoinitiator as main components, for example, a cationic polymerization composition. , Radical polymerization compositions, aqueous compositions and the like. Details will be described later.

The flat pressure member 146 is movable in the vertical direction (arrow direction shown in the figure) with the smooth surface 146a facing the recording medium P on the downstream side of the varnish coater 142 in the conveyance direction of the recording medium P. Is arranged in.
The flat pressure member 146 moves in the vertical direction, contacts the recording medium P, presses at least the surface (image surface) in the foil donation range of the recording medium P with the smooth surface 146a, and the recording medium P The ink that is ejected onto the surface of the ink and forms an image is smoothed.
The smooth surface 146a has at least an area larger than the foil donation range.

  The ultraviolet irradiation unit 148 is disposed on the downstream side of the flat pressure member 146 in the conveyance direction of the recording medium P. The ultraviolet irradiation unit 148 irradiates the recording medium P with active energy (ultraviolet rays in the present embodiment), and cures the smoothed transparent liquid applied to the surface of the recording medium P. As the ultraviolet irradiation unit 148, for example, a metal halide lamp, a high pressure mercury lamp, a UV-LED, or the like can be used.

  The varnish coater 142 and the ultraviolet irradiation unit 148 are not essential devices for smoothing the foil donation range of the recording medium P, but are installed because a smooth surface can be obtained by applying a transparent liquid. Is preferred.

The foil pressing unit 118 includes a foil supply roll 150, a foil winding roll 152, rollers 154 and 156, a foil 158, and a hot stamp plate 160, and the smoothing unit 116 in the conveyance direction of the recording medium P. It is arranged on the downstream side.
The foil supply roll 150 and the foil take-up roll 152 are arranged at a predetermined interval. Further, the roller 154 and the roller 156 are separated from each other by a predetermined distance, the surface connecting the roller 154 and the roller 156 is parallel to the surface of the recording medium P, and more than the foil supply roll 150 and the foil take-up roll 152. It is arranged at a position close to the recording medium P. The rollers 154 and 156 are arranged at positions very close to the recording medium P.
The foil 158 is supplied from the foil supply roll 150, wound around the roller 154 and the roller 156, and then stretched around the foil winding roll 152. Here, the foil 158 between the roller 154 and the roller 156 is parallel to the recording medium P.

The hot stamp plate (letter plate) 160 is disposed between the roller 154 and the roller 156 at a position facing the recording medium P via the foil 158. The hot stamp plate 160 is provided with a relief plate portion 160a that comes into contact with the foil 158 and presses the foil 158 on the surface of the recording medium P, and is formed of zinc, brass, or the like. Further, the hot stamp plate 160 has a heating device (not shown) for heating the relief plate portion 160a and a moving mechanism for moving the hot stamp plate 160 in a direction approaching or separating from the recording medium P.
The hot stamp plate 160 is heated and pressure-bonded on the recording medium P according to the shape of the relief plate portion 160a by bringing the heated relief plate portion 160a into contact with the recording medium P via the foil 158 and pressing it. To do.

Here, in the present embodiment, a transport buffer is provided between the smoothing unit 116 and the foil pressing unit 118.
By providing the transport buffer, the slack of the continuous paper-like recording medium P for label printing caused by the difference in transport speed between the smoothing unit 116 and the foil pressing unit 118 can be absorbed, and the label can be manufactured efficiently. Can do.

  The label removing unit 120 is disposed on the downstream side of the ultraviolet irradiation unit 164 in the conveyance direction of the recording medium P, and an active energy curable transparent liquid (in this embodiment, an ultraviolet curable transparent liquid) is used on the image surface. A varnish coater 162 and an ultraviolet irradiation unit 164 for improving the gloss by coating, a die cutter 166 for making a label-shaped cut in the continuous paper-like recording medium P, and a residue removing unit 172 that is an unnecessary portion peeling unit. .

The varnish coater 162 is disposed on the downstream side of the foil pressing unit 118 in the conveyance direction of the recording medium P.
The varnish coater 162 has a pair of coating rolls (impregnated) with an ultraviolet curable transparent liquid adhered to the surface thereof, and supports the movement of the recording medium P (synchronized) while sandwiching the recording medium P. By rotating, the ultraviolet curable transparent liquid is applied to the surface (the surface on which the image is formed) of the recording medium P pressed with the foil.
The ultraviolet irradiation unit 164 is disposed on the downstream side of the varnish coater 162 in the conveyance direction of the recording medium P. The ultraviolet irradiation unit 164 irradiates the recording medium P with active energy (ultraviolet rays in the present embodiment) to cure the ultraviolet curable transparent liquid applied to the surface of the recording medium P.
By applying and curing an ultraviolet curable transparent liquid on the surface of the recording medium P, the image surface of the recording medium P can be given gloss, and the image quality can be improved.

As shown in FIG. 2, the die cutter 166 is provided with a desired label-shaped cut 180 b only in the adhesive sheet 180 of the printed continuous-paper label recording medium P. A cylinder cutter 168 disposed on the downstream side of the ultraviolet irradiation unit 164 in the transport direction and disposed on the image surface side of the recording medium P, and a receiver disposed on the opposite side of the cylinder cutter 168 across the recording medium P. And a roller 170.
The cylinder cutter 168 includes a cylindrical cylinder 168a and a plurality of cutting blades 168b wound around the cylindrical surface of the cylinder 168a and formed in a label shape.

  The die cutter 166 oscillates and rotates intermittently in synchronization with the conveyance speed of the recording medium P while the recording medium P is sandwiched between the cylinder cutter 168 and the receiving roller 170, so that the cutting blade 168b is rotated. Only the P adhesive sheet 180 is cut into a label shape.

  Here, the reason why the die cutter 166 swings and rotates intermittently is to solve the problem caused by the discrepancy between the circumferential length of the cylindrical surface of the cylinder 168a and the required length of the cutting blade 168b. That is, when the die cutter 166 is continuously rotated to insert the label-shaped cut 180b, the recording medium P corresponding to the portion where the cutting blade 168b of the cylinder cutter 168 is not provided is also fed and the recording medium P is wasted. However, by rotating and rotating the die cutter 166, the cuts 180b can be formed continuously, and waste of the recording medium P can be eliminated.

The scrap removing part 172 peels off an unnecessary part (peripheral part of the label L) of the adhesive sheet 180 that does not become the label (product) L from the release paper 182 and winds it up.
The recording medium P in which the unnecessary portion is wound, that is, the recording medium P in which only the label L is attached to the release paper 182 is wound around the product winding section 134 to become a product.

Next, a method for creating a label by the digital label printing apparatus 100 will be described.
As shown in FIG. 1, the recording medium P sent out from a supply roll 122 wound in a roll shape is conveyed to the drawing unit 112 by a pair of conveying rollers 124 and 126.

The recording heads 136 </ b> Y, 136 </ b> M, 136 </ b> C, and 136 </ b> K discharge ink droplets of ultraviolet curable ink to the recording medium P that passes through the opposing positions based on control by the control unit 121. The recording medium P on which the ink has been ejected is further conveyed, passes through a position facing the ultraviolet irradiation unit 138, is irradiated with ultraviolet rays, and the ink is cured.
That is, when the recording medium P passes through the positions facing the recording heads 136Y, 136M, 136C, and 136K, ink droplets are ejected from the recording heads 136Y, 136M, 136C, and 136K toward the recording medium P, and then The ultraviolet rays are irradiated from the ultraviolet irradiation unit 138, and the ink is cured. As a result, an image is formed on the surface of the recording medium P.

  The recording medium P on which the image has been recorded is transported to the smoothing unit 116 and is thickened by the varnish coater 142 so as to cover the entire image 184 formed on the recording medium P as shown in FIG. A transparent liquid 186 having a thickness of about 5 to 30 μm (dry film thickness) is applied.

  The recording medium P coated with the transparent liquid 186 is conveyed to a position facing the flat pressure member 146. The flat pressure member 146 moves in a direction approaching the recording medium P, and presses the recording medium P with a smooth surface 146a. By pressing the recording medium P with the smooth surface 146a, the ink on the recording medium P is crushed. Thereby, the ink (image) on the recording medium P becomes smooth. Here, the area of the smooth surface 146a of the flat pressure member 146 is larger than the foil supply range.

  The recording medium P with the smoothed image is conveyed to the foil pressing unit 118 via the conveyance buffer. The recording medium P conveyed to the foil pressing unit 118 is pressed by the hot stamp plate 160 through the foil 158. On the surface of the recording medium P pressed by the hot stamp plate 160, a foil 158 is heat-pressed on the surface according to the shape of the relief plate portion 160a of the hot stamp plate 160.

  The recording medium P to which the foil 158 has been heat-pressed, that is, pressed with foil, is conveyed to the label removing unit 120 and applied with an ultraviolet curable transparent liquid by the varnish coater 162, and then irradiated with ultraviolet rays by the ultraviolet irradiation unit 164. The applied UV curable transparent liquid is cured.

The recording medium P in which the ultraviolet curable transparent liquid is cured is conveyed to a die cutter 166, and a cut 180b is formed in the shape of the label L only on the adhesive sheet 180 by the cylinder cutter 168 and the receiving roller 170.
At this time, as described above, since the die cutter 166 makes the cut 180b having the shape of the label L while swinging intermittently, the cut 180b can be continuously formed, and the recording medium P is wasted. The part never occurs.
Thereafter, unnecessary portions other than the label L of the pressure-sensitive adhesive sheet 180 of the recording medium P are peeled off from the release paper 182 and taken up by the residue removing portion 172. The recording medium P in a state where only the label L is stuck on the release paper 182 is wound around the product winding unit 134 to become a product.
A label is created as described above.

  Here, as shown in FIG. 6A, the image surface of the recording medium P is three-dimensionally swelled by overlapping the cured inks 184 of a plurality of colors. The rise height of the ink varies depending on the ink absorbability of the recording medium P (the lower the absorbency, the higher the height), but it is about 10 μm per color, and when one multicolor ink is used. May be approximately 40 μm. The image surface of the recording medium P is uneven. This unevenness greatly affects the adhesion between the foil 158 and the recording medium P (more specifically, the ink 184 on the recording medium P) when foil-pressing the image surface of the recording medium P.

  That is, as shown in FIG. 6B, when foil pressing is performed on an image surface in which the foil donation range is not smoothed (in other words, the ultraviolet curable ink is discharged and cured in the drawing unit 112), The foil 158 is heated and pressure-bonded only on the concave and convex peak portions, and is not pressed on the valley portions. That is, the degree of adhesion between the foil 158 and the recording medium P is low, and is easily peeled off.

  In contrast, in the present embodiment, the foil donation range is smoothed in advance by the flat pressure member 146 and then pressed onto the recording medium P. As a result, as shown in FIG. 6C, the foil 158 can be heat-bonded to a smooth surface having a large area, and the foil pressing with high adhesion between the recording medium P and the foil 158 is difficult. it can.

That is, according to the digital label printing apparatus 100 of the present embodiment, smoothing is performed by using the flat pressure member 146 to smooth the ink 184 and the transparent liquid 186 in at least the foil donation range on the recording medium P upstream of the foil pressing unit 118. By disposing the portion 116, the foil 158 can be provided and pressed in the range smoothed by the smoothing portion 116.
Thereby, the adhesiveness of the recording medium P and the foil 158 can be improved, and favorable foil stamp printing can be performed. Moreover, since it is smoothed by the flat pressure member 146, it can be smoothed in a short time, and productivity can be improved.

  Further, a transparent liquid supply means (varnish coater) 142 for supplying the smoothing unit 116 with a transparent active energy curable liquid on the image surface on the recording medium P, and an active energy curable liquid (transparent liquid) after supply. Active energy irradiation means (ultraviolet irradiation unit) 148 for irradiating active energy is provided, and the image surface is covered and smoothed with a transparent active energy curable liquid so that the image surface has large irregularities. A foil donating range with good flatness can be formed.

  Furthermore, by using a varnish coater as the transparent liquid supply means, the transparent liquid 186 can be stably applied to the surface of the recording medium P on which the uneven image is formed with a simple and inexpensive mechanism.

  Here, the formation of the film of the ultraviolet curable transparent liquid by the varnish coater 162 and the ultraviolet irradiation unit 164 is not necessarily required because it is intended to give the image surface a gloss and obtain a high-quality image. When not required, it can be set not to form a film of an ultraviolet curable transparent liquid.

Here, as shown in FIGS. 7A and 7B, when the amount of ink droplets ejected from the ejection unit is smaller than the desired amount, the ejection unit number described later is ejected with A11. Like the droplet ejection point formed by the portion 60, the size of the droplet ejection point becomes small. As described above, when the size of the droplet ejection point is different from the desired size, streaks and unevenness occur in the formed image.
In addition, as shown in FIGS. 7A and 7B, the ink droplets ejected from the ejection unit when the image is drawn by the recording head unit 135 are different from the ink droplets ejected from the other ejection units. When the ink droplet is ejected, the position of the ink droplet ejection point is shifted as in the droplet ejection point formed by the ejection unit 60 having the ejection unit number A5 described later, that is, the landing position of the ink droplet is Deviation and streaks and unevenness occur in the formed image.
A method for detecting the droplet ejection point size that causes streaks and unevenness by the digital label printing apparatus 100 and a method for detecting the interval (positional deviation) between droplet ejection points will be described. Here, since the droplet ejection point size detection method and the droplet ejection point position detection method are performed in the same manner for any of the recording heads 136Y, 136M, 136C, and 136K, the recording head 136K will be described below as a representative. .

First, an image (hereinafter also referred to as “droplet point position detection image”) used to detect the droplet ejection point position is drawn on the recording medium P by the recording head 136K.
In the present embodiment, when a plurality of ejection units arranged in a line are defined as A1, A2, A3,..., An in order from one end to the other end (see FIGS. 7 and 8), A1, A3 , A5,..., And a predetermined number of ink droplets are ejected only from the odd-numbered ejection portions to form a row of droplet ejection points (a droplet ejection point sequence) for each ejection unit. At this time, the droplet ejection points formed by the ink droplets ejected from one ejection unit are ejected at intervals that do not contact other droplet ejection points. Also, the droplet ejection points of the ink droplets ejected by the ejection part A1 and the ejection part A3 do not contact each other.
After a predetermined number of ink droplets are ejected from the odd-numbered ejection portions, similarly, a predetermined number of ink droplets are ejected from the even-numbered ejection portions A2, A4, A6,. A droplet ejection point is formed on the medium P. Here, the droplet ejection points formed by ejecting a predetermined number of ink droplets from the even-numbered ejection portions are also formed at positions where each droplet ejection point does not contact other droplet ejection points.

Next, a high density is used to detect the droplet ejection spot size on the recording medium P by ejecting ink droplets from all the ejection portions of the recording head 136, that is, the ejection portions A1, A2, A3. A droplet ejection point is formed on the surface, and an image used for detection of the droplet ejection point size (hereinafter also referred to as “image for droplet ejection point area detection”) is formed. Here, in the present embodiment, ink droplets are continuously and alternately ejected from the odd-numbered ejection sections and the even-numbered ejection sections to form a checkered pattern-like image. Here, the droplet ejection point area calculation image (image density detection image) may be in contact with the droplet ejection point and the adjacent droplet ejection point.
Further, the timing at which the ink ink droplets are ejected from the ejection unit, that is, the arrangement pattern of the droplet ejection points on the recording medium is not particularly limited, and various patterns can be used.
In this embodiment, while the recording medium P is transported in the transport direction, that is, the direction orthogonal to the recording head 136K by the transport unit 110, ink droplets are ejected from the respective ejection units of the recording head 136K onto the recording medium. Forms a droplet injection point.

FIG. 8 is a top view showing an example of an image (test pattern) used for detecting a droplet ejection point position and droplet ejection point size.
In this way, an image is drawn on the recording medium, that is, droplet ejection points are formed. As shown in FIG. 8, an odd number which is an image for detecting the droplet ejection point position is formed on one recording medium P. An ejection point aggregate G _A formed by ejecting ink droplets from the numbered ejection part, and an ejection point aggregate G _B formed by ejecting ink droplets from the even numbered ejection part; ejecting ink droplets from all the ejection portions are droplet dot area calculation image, to form an aggregate and G _C of droplet deposition points are disposed at a high density.
In other words, the droplet ejection point position detection image is formed by ejecting ink droplets selectively from a plurality of ejection units without ejecting ink droplets simultaneously from all ejection units. In a direction orthogonal to the extending direction (arrangement direction), a row of droplet ejection points is formed at a plurality of different portions. That is, the rows of droplet ejection points formed on the recording medium are formed at different positions in the direction orthogonal to the arrangement direction of the ejection units, according to the arrangement positions of the ejection units. Here, the extending direction of the discharge part is the direction in which the plurality of discharge parts are arranged, that is, the direction in which the line connecting the discharge parts extends, in other words, the longitudinal direction of the recording head (inkjet head), In this embodiment, it is the width direction of the recording medium.
In addition, the droplet ejection point area detection image allows ink droplets to be ejected simultaneously from all ejection sections or evenly ejected from all ejection sections in a predetermined pattern, resulting in a high density of droplet ejection points. An aggregate of the applied droplet ejection points is formed. Here, the droplet ejection point area detection image has the droplet ejection points arranged at a higher density than the droplet ejection point position detection image.

Next, the droplet ejection point detecting unit 114, first, aggregate G _A droplet ejection points which is the droplet deposition point position detection image from the image formed on the recording medium _P, and reads the aggregate G _B. That is, by droplet deposition point detecting unit 114, aggregates _{G A,} and reads the respective droplet ejection points of the aggregate _{G B.} The read image data is sent to the control unit 121.

FIG. 9A is a schematic diagram showing one droplet ejection point of an image (read image) read by the droplet ejection point detection unit 114, and FIG. 9B is an image shown in FIG. 9A. It is a schematic diagram which shows an example which binarized data. Here, in each of FIGS. 9A and 9B, each square is one pixel. By increasing the reading pixel density, that is, the reading resolution, each cell can be made smaller, and one droplet ejection point can be read more finely.
The arithmetic unit (not shown) of the control unit 121 uses the droplet ejection point image read by the droplet ejection point detection unit 114 (see FIG. 9A) as a binary value for each pixel as shown in FIG. 9B. Turn into. In other words, it is determined whether or not the ink density of each pixel, that is, the density of the read image is equal to or higher than a threshold value. The pixel has no ink component. In other words, each read pixel has only two values with or without an ink component.

Next, binarization is performed, and only the pixels that form the droplet ejection point, that is, the pixels having an ink density within a certain level are taken out, and a plurality of droplet ejection points formed by one ejection unit are arranged. One end of the droplet ejection point (hereinafter also simply referred to as “one end”) in a direction (reference direction) orthogonal to a direction substantially parallel to the direction in which the droplet is deposited, and the other end in the reference direction of the droplet ejection point The coordinates of the pixel (hereinafter also simply referred to as “the other end”) are calculated.
Here, the coordinate axis of the calculated coordinates is orthogonal to the reference direction, with the extending direction of the droplet ejection point detection unit 114, that is, the direction substantially orthogonal to the transport direction of the recording medium P as the reference direction (X-axis direction). A direction, that is, a direction substantially parallel to the conveyance direction of the recording medium P is defined as a Y-axis direction, and an arbitrary point is defined as an origin. This coordinate axis is a common coordinate axis for all droplet ejection points.
Specifically, as shown in FIGS. 10 (A) and 10 (B), the extreme end pixels (left end and right end in the figure) in the reference direction of the droplet ejection point are detected, and the coordinates of the detected pixels are determined. The coordinates of the ends 190 and 190 ′ of the droplet ejection point are used. Further, as shown in FIG. 10B, when a plurality of pixels are detected as the pixels at the end of the droplet ejection point, that is, pixels having the same coordinate in the reference direction (the hatched portion in FIG. 10B). When a plurality of pixels are detected, the average value of the plurality of pixels is defined as the end portion 190 ′. That is, the coordinates of the end portion 190 ′ in the reference direction are the same coordinates for each detected pixel, and the Y-axis direction coordinates of the end portion 190 ′ are the average value of the detected Y-axis direction coordinates. To do.

  Next, the calculated coordinates (droplet point position information) at both ends of each droplet discharge point are classified by discharge unit and by end. Here, the relationship between the droplet ejection point and the ejection unit that ejected the droplet is the positional relationship between the droplet ejection points in the recording medium conveyance direction and the direction perpendicular thereto, and the reference direction (X-axis) between the droplet ejection points. Direction) and a relative relationship such as a positional relationship in a direction orthogonal to the reference direction (Y-axis direction), each droplet ejection point can be classified for each ejection unit.

Here, FIG. 11 is an enlarged top view showing an enlarged part of a row of droplet ejection points.
As a method for classifying the droplet ejection points by discharge unit and by end, as shown in FIG. 11, a predetermined distance d _a and a predetermined angle 2θ with reference to the coordinates of the calculated ends 190 and 190 ′ of the droplet ejection point. The other end portions 192 and 192 ′ detected in the ranges Z and Z ′ form droplet ejection points formed by ink droplets ejected from the same ejection portion, that is, the same droplet ejection point rows. There is a method of classifying as an end portion on the same side of adjacent droplet ejection points. In the present embodiment, the predetermined angle θ is based on a direction orthogonal to the reference direction (a direction parallel to the Y axis), and the ranges Z and Z ′ are center angles 2θ and distances inclined by θ in both directions from the reference. It was a fan shape.

Here, whether the end of the droplet ejection point is one end or the other end, that is, whether it is the left end or the right end in FIG. 11, is classified according to the image data. It is preferable. As a result, the end of the droplet ejection point is changed to one end (end near the Y axis, right end) and the other end (end far from the Y axis, left end). It is possible to classify and classify the droplet ejection points.
In this way, by separating one end portion from the other end portion and classifying the droplet ejection points, the other end portion of the adjacent droplet ejection points or the adjacent droplet ejection formed by the same ejection unit It can prevent detecting the other edge part of a point as an edge part of the droplet ejection point formed by the same discharge part.
Further, even when the Y-axis direction and the actual arrangement direction (extending direction) of the row of droplet ejection points are deviated, adjacent droplet ejection points can be suitably detected.

  Further, by detecting the end of the droplet ejection point within a predetermined range as the droplet ejection point formed by the same ejection unit, a droplet ejection point that should be originally formed at an adjacent position due to ejection failure or the like is formed. Even if not, the end of the droplet ejection point formed by the same ejection part formed at a further distance in the Y-axis direction is detected, and one or the other of the droplet ejection points formed by the same ejection part Can be categorized as an end.

Next, with regard to the droplet ejection points classified for each end of the ejection unit, each of the ends (one end and the other end) of a plurality of droplet ejection points ejected from one ejection unit is a least square method. As shown in FIG. 12, an approximate straight line connecting one end of the droplet ejection point (the left end of the droplet ejection point in FIG. 12) and the other end (FIG. 12). 12, the approximate straight line connecting the right end of the droplet ejection point) is calculated.
Specifically, if the number of the ejection unit is m, the approximate straight line at one end of the droplet ejection point formed by the ejection unit _m is expressed as y = ax + b _m based on the coordinate axis described above. Further, the approximate straight line at the other end is expressed as y = ax + _cm .
Note that a is the slope of the approximate line, b _m is the intercept of the approximate line at one end, and _cm is the intercept of the approximate line at the other end. The slope a of the approximate line is calculated as a slope common to all approximate lines. Accordingly, the approximate straight lines are all parallel to each other.
The slope a, the intercept b _m and the intercept _cm are calculated by the following formulas (1), (2) and (3).

Here, M is the total number of ejection units, m is the number of ejection units, Nm is the number of droplet ejection points drawn by the ejection unit m to calculate a straight line, and (xl _mn , yl _mn ) Is the coordinates of the n-th one end (left side end) detected from the droplet ejection point drawn by the ejection unit m, and (xr _mn , yr _mn ) is from the droplet ejection point drawn by the ejection unit m. It is the coordinate of the detected nth other edge part (left edge part).

Furthermore, the interval between the droplet ejection points is calculated from the calculated approximate straight lines a, b _m and _cm . When the distance between the droplet ejection point of the discharge portion m and the droplet ejection point of the discharge portion m + 1 was d _m, d _m is calculated by the following equation (4).

  By calculating the interval between the droplet ejection points as described above, it is possible to calculate (detect) the positional deviation of the droplet ejection points of the ink droplets ejected from each ejection unit.

Next, the position of the droplet ejection point is detected from the calculated approximate straight lines a, b _m and _cm . When the position of the droplet ejection point formed by the discharge unit m is P _m , the position P _{m of the} droplet ejection point is calculated by the following equation (5).

Next, the droplet ejection point detecting unit 114, the droplet ejection dot area calculation image that is read the aggregate G _C of droplet deposition points are arranged at a high density, and sends the read image data to the control unit 121. The control unit 121 calculates the image density from the droplet ejection point area calculation image.
Here, the image density is an image density in a direction parallel to the reference direction (X-axis direction). The image density is an image density for several droplets in the Y-axis direction, that is, an image density with a predetermined width, or a line in a direction parallel to a plurality of reference directions (X-axis direction) having different positions in the Y-axis direction. Is preferably calculated. Thus, by calculating the image density in the reference direction based on a plurality of droplet ejection points, the change in the image density in the reference direction can be accurately calculated. Further, C in Expression (5) is a droplet ejection point detected based on the relationship between the recording medium and the droplet ejection point, and further, the relationship between the droplet ejection point position calculation image and the droplet ejection point area detection image. This is the position of the ejection section with m = 1 in the area calculation image. In the present embodiment, C is the value of the x coordinate of the droplet ejection point of the ejection portion of m = 1 on the droplet ejection point area calculation image on the coordinates used for detecting the position of the droplet ejection point described above.

The arithmetic unit (not shown) of the control unit 121 determines the droplet ejection spot size of each ejection unit based on the read image density of the droplet ejection area calculation image and the droplet ejection point position of the ejection unit calculated by the above equation (5). Is calculated (detected). In other words, based on each calculated droplet ejection point position, the density distribution of the image density of the droplet ejection area calculation image is analyzed, and the droplet ejection point size of each ejection unit is detected. Specifically, as shown in FIG. 13A, the position of the droplet ejection point calculated by the above equation (5) is assigned to the measured image density, and the image density corresponding to each droplet ejection point is detected (calculated). To do. For example, as shown in FIG. 13A, the measured image density at the position Pm corresponding to the position of the droplet ejection point of the ejection unit m with the ejection unit of m = 1 as the reference is the droplet ejection point of the ejection unit m. The image density is detected.
Next, the size of each droplet ejection point is calculated from the detected image density of each droplet ejection point, using the relationship between the droplet ejection point size and the image density calculated in advance as shown in FIG.
Here, in the present embodiment, an example of the relationship between the image density and the droplet ejection point size is simply shown, but the droplet ejection point size of each ejection unit is the position of the droplet ejection point of each ejection unit, the image density, Furthermore, it is preferable to detect based on a relationship such as an interval between adjacent droplet ejection points and an increase or decrease in image density.
In addition, even if the size of the droplet ejection point is detected every time the position of the droplet ejection point of the ejection unit is detected, the measured image density data is used after the detection of the position of the droplet ejection point of all the ejection units is completed. Thus, the size of the droplet ejection point of each discharge unit may be detected.
The size of the droplet ejection point of each discharge unit is calculated as described above.

  Here, FIG. 14 is a front view showing an example of the relationship between the ejection unit and the droplet ejection point formed on the recording medium, and FIG. 15 shows the droplet ejection spot size without being based on the droplet ejection point position. FIG. 16 is an explanatory view schematically showing the relationship between each ejection unit, the size of the droplet ejection point, and the image density when detected, and FIG. 16 shows each case when the droplet ejection point size is detected based on the droplet ejection point position. It is explanatory drawing which shows typically the relationship between the size of an ejection part, a droplet ejection point, and image density.

  As shown in FIG. 14, the size of ink droplet ejection points of ink droplets ejected from each ejection unit and landed on the recording medium P has various sizes. In addition, there are also ejection units that eject ink droplets in a direction different from other ejection units, such as ejection unit Aα and ejection unit Aβ in FIG. In other words, there are some ejection units in which the ink droplet flying direction is different from other ejection units and the droplet ejection point position is different from the desired position.

For this reason, as shown in FIG. 15, when the image density is read and the size of each droplet ejection point is simply detected based on the arrangement of the ejection unit, if the droplet ejection point is not formed at a desired position, accurate ejection is performed. Droplet size cannot be detected.
That is, when the size of the droplet ejection point is determined based on the image density at the position corresponding to the ejection unit, the droplet ejection point positions are shifted as in the ejection unit Aα and ejection unit Aβ in FIG. If the landing position of the ink droplets discharged from the ink droplets is landing at a desired position, for example, a position different from the set value, the droplet ejection spot size cannot be detected with the exact density of the corresponding droplet ejection spot. .

On the other hand, as shown in FIG. 16, the present invention detects the size of the droplet ejection point of each ejection unit based on the image density in consideration of the calculated droplet ejection point position. Specifically, the ejection units whose ejection point positions are shifted, such as the ejection unit Aα and the ejection unit Aβ, are corrected in consideration of the displacement of the droplet ejection point positions, that is, based on the droplet ejection point positions. Thus, the size of the droplet ejection point of each discharge unit is detected.
In this way, the size of each droplet ejection point can be detected more accurately (highly accurately) by detecting the size of the droplet ejection point in consideration of the position of the droplet ejection point.
That is, as shown in FIG. 16, based on the calculated droplet ejection point position of each ejection unit, the image density is analyzed, and the calculated image density is allocated to an appropriate ejection unit, whereby the droplet ejection point of each ejection unit. The size can be detected accurately (high accuracy).

  That is, according to the present invention, the dot boundary line is determined by detecting the droplet ejection spot size based on the image density using the image for calculating the droplet ejection spot area having a high image density in which the droplet ejection points are arranged at a high density. It is possible to detect the size of the droplet ejection point based on an image in which the size of the droplet ejection point is more reflected than in the case of detection, and more accurately by adding the position of the droplet ejection point as described above. The size of the droplet ejection point can be detected with high accuracy.

Here, it is preferable that the image density for droplet ejection area calculation is 40% or more and 60% or less.
By setting the image density to 40% or more and 60% or less, the droplet ejection spot size (area) can be more reflected in the image density. The droplet ejection spot size can be detected more accurately (highly accurate) based on the change in image density.

  Further, in the present embodiment, the approximate straight lines are calculated for both ends of each droplet ejection point for each ejection unit, and the droplet ejection point position is calculated, but the center of each droplet ejection point is calculated for each ejection unit, The droplet ejection point position may be calculated by calculating an approximate straight line connecting the centers of a plurality of droplet ejection points corresponding to the respective ejection units.

  In addition, since the droplet ejection point position can be detected more accurately, an approximate straight line at each end of a plurality of droplet ejection points is calculated for each ejection unit and calculated as in this embodiment. However, the present invention is not limited to this, and the droplet ejection point position may be calculated by various methods.

  Furthermore, by calculating the droplet ejection point interval by comparing approximate straight lines calculated from a plurality of droplet ejection points for each discharge unit, it is possible to accurately calculate (detect) the droplet ejection points, such as stripes, unevenness, etc. It is possible to accurately obtain information (ejection information on the flying direction of droplets) of the ejection part where the position of the droplet ejection point, which is the cause of the deviation, is shifted.

  In addition, the number of droplet ejection points (reading number, measurement number) for each ejection unit can be an arbitrary number, and can be variously set according to the required accuracy. Further, even when using a reading device with low reading accuracy, that is, a low resolution reading device, by increasing the number of ink droplets to be read, the position of the ink droplets and the position of the ink droplets are displaced with high accuracy. Can be detected.

  Further, as in this embodiment, an approximate straight line at both ends of the droplet ejection point is calculated for each droplet ejection point row, that is, for each ejection unit, and droplet ejection is performed based on the approximate straight lines at both ends, that is, two approximate lines. By calculating the point position and the droplet ejection point interval, a more accurate droplet ejection point interval can be calculated. That is, since the droplet ejection point interval can be calculated using only the coordinates of the end of the droplet ejection point without calculating the center for each droplet ejection point, the calculation can be simplified.

Further, if all the droplet ejection points of the droplet ejection point position detection image are drawn on the same recording medium, the same direction in which the ejection unit extends (the direction perpendicular to the conveyance direction of the recording medium). Even if the droplet ejection points of all the ejection parts are not formed on a straight line, for example, the ejection is performed on a plurality of different parts in a direction (recording medium transport direction) perpendicular to the extending direction of the ejection part on the recording medium. Even when droplet points are formed, the droplet point interval and droplet point size can be suitably calculated.
In addition, by shifting the position of the droplet ejection point in the direction parallel to the transport direction, even when the arrangement density of the ejection parts is high and adjacent droplet ejection points overlap, the droplet ejection point is not reduced, etc. It is possible to calculate the drop point interval and the drop point size.

  Further, as in the present embodiment, the droplet ejection point position detection image and the droplet ejection point area calculation image are formed on the same recording medium, that is, on the same recording medium. Correspondence with the concentration can be easily and accurately taken, and the droplet ejection spot size can be detected more easily and accurately. From these points, it is preferable that the droplet ejection point position detection image and the droplet ejection point area calculation image are formed on the same recording medium. It can also be formed on other recording media. As a method of taking correspondences between the respective droplet ejection points, for example, there is a method in which ink droplets are always ejected from one ejection unit to form a reference droplet ejection sequence on a recording medium.

Here, the number of droplet ejection points read for each ejection unit, the size of the droplet ejection point (resolution of the image drawn by the recording head), and the resolution of the image reading device (line sensor) of the droplet ejection point detection unit The relationship between [the number of measured droplet ejection points drawn by one ejection unit] × [resolution of droplet ejection points (resolution of the image rendered by the recording head, minimum interval)] / [reading by the image reading apparatus] Resolution (minimum reading interval)]> 100 is preferably satisfied.
By satisfying the above formula, it is possible to accurately calculate the interval between the droplet ejection points, and it is possible to accurately calculate the positional deviation of the droplet ejection points.

In the present embodiment, as droplet deposition point position detection image, the droplet ejection points formed on the recording medium P, a collection G _A droplet ejection points formed by the odd ejection portions, even Although divided into aggregate G _B of droplet ejection points formed by the discharge portion, the present invention is not limited thereto, be divided into three to form a row of droplet ejection point, in four A row of droplet ejection points may be formed.

Further, if the adjacent droplet ejection points are not in contact with each other on the recording medium, that is, if the droplet ejection point and the adjacent droplet ejection point are not in contact with each other, the droplet ejection points formed by all the ejection units are set on the recording medium. You may form on the same straight line in the direction perpendicular | vertical to a conveyance direction.
For example, if the size of the ejected ink droplet can be adjusted, that is, if the size of the droplet ejection point can be adjusted, the droplet ejection point can be reduced by reducing the droplet ejection point by reducing the ejected ink droplet. You may make it not contact an adjacent droplet ejection point.
In this way, by not contacting the droplet ejection point adjacent to the droplet ejection point, both ends of each droplet ejection point in the reference direction can be accurately calculated.

Further, in this embodiment, an image is formed in which droplet ejection points are continuously formed only by an odd number of ejection portions and droplet ejection points are continuously formed only by an even number of ejection portions, but the present invention is not limited to this. Alternatively, an image in which droplet ejection points are alternately formed by odd-numbered ejection portions and even-numbered ejection portions may be used.
In this way, even when the adjacent droplet ejection points of each ejection unit are formed apart from each other, that is, in the direction orthogonal to the reference direction, it is formed by another ejection unit between the droplet ejection points formed by the same ejection unit. Even if the formed droplet ejection points are formed, an approximate straight line for each ejection unit can be calculated in the same manner, and the droplet ejection point interval and droplet ejection point size can be calculated (detected).

  Further, in order to accurately calculate the droplet ejection points between all the ejection units, it is preferable to form all the droplet ejection points on one recording medium. However, the present invention is not limited to this. The droplet ejection point interval may be calculated by forming droplet ejection points. In this case, ink droplets are always ejected from some ejection units, that is, droplet ejection points are formed on all of the plurality of recording media, and droplet ejection points serving as a reference are formed. By taking correspondence between the recording media, it is possible to detect the droplet ejection point size of all ejection units and the droplet ejection point position deviation between all ejection units.

  Further, the method of calculating the approximate line is not limited to the least square method, and various calculation methods can be used. For example, a slope (y = ax + b) of a straight line (y = ax + b) calculated from two adjacent points, that is, one end portion of the droplet ejection point formed by the same ejection unit and one end portion of the adjacent droplet ejection point ( The slope (α) and the intercept (β) of the approximate line may be calculated by averaging a) and the intercept (b). More specifically, the number of droplet ejection points formed by one ejection unit is N, the x coordinate of the i-th one or other end point of the droplet ejection point is xi, and i of the droplet ejection point is i. An approximate straight line can also be calculated using the following equation (6), where y coordinate of one or the other end of the th point is yi.

  In this embodiment, in addition to the droplet ejection point size, the positional deviation of the droplet ejection point (interval between droplet ejection points) is also detected from the above formula (4). However, the present invention is not limited to this, and droplet ejection is performed. It is not always necessary to calculate the positional deviation of the points, and only the droplet ejection point size may be detected.

  In this embodiment, the active energy curable ink is used as the ink, and the active energy curable ink is ejected from the recording head to form an image of the active energy curable ink on the recording medium P. Although described as a digital label printing apparatus that irradiates light, cures an image, and fixes an image on a recording medium, the present invention is not limited to this, and will be described in detail later with specific examples. An ink jet drawing apparatus that fixes an image on the recording medium P by heating and pressurizing the image recorded on the recording medium P can also be used.

  In the above-described embodiment, the recording head of the drawing unit is a full-line head type in which the ejection units are arranged in a line. However, the recording head is not limited to a single-row arrangement, and as shown in FIG. 640 may be arranged in a staggered manner by shifting a plurality of rows of ejection portions by a certain pitch. In this manner, by arranging the ejection units 60 in a staggered manner and forming one row of droplet ejection points with a plurality of rows of ejection units, it is possible to form an image with higher resolution.

  Here, in this embodiment, the image data detected by the droplet ejection point detection unit is sent to the control unit, the image data is processed by the arithmetic unit of the control unit, and the droplet ejection point size and the position deviation of the droplet ejection point are detected. However, the present invention is not limited to this, and an arithmetic unit may be provided in the droplet ejection point detection unit.

  Further, in the present embodiment, the droplet ejection point detection unit and the control unit are provided with the arithmetic unit in the inkjet drawing apparatus, but the present invention is not limited to this, and the droplet ejection point detection unit is provided in the inkjet drawing apparatus. Without being provided, it is also possible to use a position size detection device that reads a recording medium on which an image has been drawn by an ink jet drawing device, and detects the size of a droplet ejection point by the same method as described above.

As an example, as shown in FIG. 18, even when the digital label printing device 650, the calculation device 660, and the image reading device 670 are separate devices, the positional deviation of the droplet ejection point and the droplet ejection point size are detected. Can do.
The digital label printing apparatus 650 is an apparatus that forms an image on the recording medium P using a full-line head type ink jet head, and the arithmetic unit 660 is an ejection for forming an image on the recording medium from input image data. The image reading device 670 is a device that reads an image formed on the recording medium P by the digital label printing device 650. Here, the ejection signal refers to an ejection unit to be driven among a plurality of ejection units of the recording head according to the conveyance of the recording medium P, timing for ejecting ink droplets from the ejection unit, amount of ejected droplets, etc. For example, in the case of a piezo-type ink jet head, this is a signal for controlling the height, length, timing, etc. of the voltage applied to the actuator for each ejection unit.

In the case of such an apparatus configuration, first, the droplet ejection point position detection image and the droplet ejection point area calculation image data are input to the arithmetic device 660. Specifically, image data of an image as shown in FIG. 8 is input.
The arithmetic device 660 calculates an ejection signal from the input image data and sends it to the digital label printing device 650. The digital label printing device 650 forms an image on the recording medium P based on the ejection signal calculated by the arithmetic device 660. In this manner, the droplet ejection point position detection image and the droplet ejection point area calculation image are formed. Note that the droplet ejection point position detection image and the droplet ejection area calculation image include a plurality of droplet ejection points for each ejection unit on a single recording medium as shown in FIG. Are images formed at positions where they are not in contact with each other, and images in which droplet ejection points are arranged at high density.

Next, the image reading device 670 reads the droplet ejection point position detection image and the droplet ejection point area calculation image. The image reading device 670 calculates the positional deviation (interval) of the droplet ejection point and the droplet ejection point size from the read image, and sends the calculated information to the arithmetic device 660. The method for calculating the position of the droplet ejection point and the size of the droplet ejection point from the read image data is the same as described above. Further, it is also possible to detect the positional deviation of the droplet ejection point by the same method as described above.
The arithmetic device 660 calculates a correction value based on the acquired droplet ejection point size information, preferably further based on the droplet ejection point positional deviation information.
Thereafter, when normal image data is input, the arithmetic device 660 calculates an ejection signal from the input image data while taking into account the calculated correction value.
The digital label printing apparatus 650 forms an image on the recording medium P based on the acquired ejection signal.
In this way, by calculating the ejection signal by taking into account the droplet ejection point size, preferably further the positional deviation of the droplet ejection point, and rendering the image with the digital label printing device, rendering the image without streaks or unevenness Can do.

Here, in the present embodiment, the calculation device, the digital label printing device, and the image reading device are divided into three, but the present invention is not limited to this, and the calculation device and the digital label printing device are used as one device. Also good. In addition, the image reading device only reads the droplet ejection point position detection image and the droplet ejection point area calculation image, and the calculation device calculates the droplet ejection point position and the droplet ejection point size from the read image data. Further, it is possible to calculate the positional deviation (interval) of the droplet ejection point and the correspondence between the droplet ejection point and the ejection unit of the recording head.
In this embodiment, the digital label printing apparatus is used. However, when the digital label printing apparatus is an ink jet drawing apparatus, each apparatus can be a separate apparatus in the same manner as described above.

Hereinafter, the droplet ejection point size detection method and the droplet ejection point position shift detection method will be described in more detail with specific examples.
FIG. 19 (A) is a schematic top view showing an image for detecting the droplet ejection position and an image for calculating the droplet ejection area (test pattern) used in this example, and FIG. 19 (B) is a diagram illustrating FIG. It is the schematic top view which showed (A) in detail.
In this embodiment, the digital label printing apparatus and the image reading apparatus that reads the recording medium on which the droplet ejection point for detecting the position of the droplet ejection point and the area for calculating the droplet ejection point are formed are separate devices.
The recording head unit of the digital label printing apparatus has 2544 ejection portions designed so that droplet ejection points are formed at intervals of 42.3 μm, and ejects UV curable (ultraviolet curable) ink. Further, in the present embodiment, the positional deviation of the droplet ejection point and the droplet ejection point size of only the recording head that discharges the ultraviolet curable cyan ink in the recording head unit are detected.
A general-purpose scanner having a resolution of 4800 dpi (measurement interval = 5.29 μm) was used as the image reading apparatus.
Further, coated paper (manufactured by EPSON, photographic paper (gloss), KA4100PSK) was used as the recording medium P.

Next, the recording medium P was conveyed at 400 mm / s, ink droplets were ejected from the recording head, and 70 droplet ejection points were created on the recording medium P for each ejection unit.
Specifically, the discharge units are divided into four groups 4k-3, 4k-2, 4k-1, 4k (k = 1, 2, 3,...) Based on the numbers of the discharge units, Ink droplets are ejected from the ejection unit with the ejection unit number of 4k-3, and 70 droplet ejection points are formed for each ejection unit. Thereafter, the ink is ejected from the ejection unit with the ejection unit number of 4k-2. 70 droplet ejection points are formed for each ejection unit, and thereafter, similarly, ejection is performed for the ejection unit with the ejection unit number 4k-1 and the ejection unit with the ejection unit number 4k. 70 droplet ejection points are formed for each copy, and an image for detecting the droplet ejection point position is formed.
That is, as shown in FIGS. 19A and 19B, the interval between the droplet ejection points in the width direction of the recording medium P is 169.2 μm on the recording medium P, and further, the recording medium Four (G1, G2, G3, G4) grids of droplet ejection points corresponding to the four groups of the ejection units are formed so that the interval between the droplet ejection points in the direction parallel to the transport direction of P is also 169.2 μm. Is done. The four gratings are formed at positions shifted by 42.3 μm from the adjacent gratings in the width direction of the recording medium P.
Further, ink droplets are ejected from the ejection unit in a fixed pattern to form an image (G5) in which the droplet ejection points are arranged in a checkered pattern at high density, thereby forming a droplet ejection point area detection image.

In this way, the droplet ejection point is created and the recording medium P on which the droplet ejection point position detection image and the droplet ejection area detection image are formed is read by the above-described 4800 dpi reader, and the droplet ejection point position is read. The droplet ejection point size and the droplet ejection point interval were calculated.
As described above, the method for calculating the droplet ejection point size and the method for calculating the interval (positional deviation) between the droplet ejection points is to calculate the coordinates of both ends of each droplet ejection point in the read droplet ejection point position detection image. The droplet ejection points are classified for each discharge unit, and an approximate straight line connecting one end of the droplet discharge point corresponding to the discharge unit and an approximate straight line connecting the other end are calculated, and from the calculated approximate straight line The droplet ejection point position and the droplet ejection point interval are calculated.
Further, the droplet ejection spot size is detected based on the read image density of the droplet ejection spot area calculation image and the detected droplet ejection spot position.
FIG. 20A shows the calculation result of the droplet ejection point size, and FIG. 20B shows the calculation result of the droplet ejection point interval.
As shown in FIG. 20A, it can be seen that the deviation between the droplet ejection point size and the desired droplet ejection point size can also be accurately detected. Further, as shown in FIG. 20B, it can be seen that a deviation between the interval between the droplet ejection points and the design value can be detected accurately.

Next, another example of the digital label printing apparatus will be described with reference to FIG.
The digital label printing apparatus 101 shown in FIG. 21 has the same configuration as the digital label printing apparatus 100 shown in FIG. 1 except for the position of the buffer. Accordingly, the same reference numerals are given to the same components in both, and the detailed description thereof will be omitted, and the points peculiar to the digital label printing apparatus 101 will be mainly described below.
In the digital label printing apparatus 101 shown in FIG. 21, a buffer is disposed between the drawing unit 112 and the smoothing unit 116. Thus, the position of the transport buffer is not particularly limited, and can be various ones.

22 is a front view showing a schematic configuration of another example of the ink jet drawing apparatus 710 using the droplet ejection point deviation detection method of the present invention, and FIG. 23 is a suction belt conveyance unit of the ink jet drawing apparatus 710 shown in FIG. 736 is a top view showing a recording head unit 750 and 736. FIG.
The inkjet drawing apparatus 710 basically includes a supply unit 712 that supplies the recording medium P, a conveyance unit 714 that conveys the recording medium P supplied from the supply unit 712 while maintaining flatness, and a conveyance unit. A drawing unit 716 disposed opposite to the recording medium 714 and having a recording head unit 750 for drawing an image on the recording medium P, an ink storage / loading unit 752 for storing ink to be supplied to the recording head unit 750, and the like. Is recorded on the recording medium P by the heating and pressing unit 718 that heats and presses the recording medium P on which the image is drawn, the discharge unit 720 that discharges the recording medium P on which the image is drawn, and the drawing unit 716. A droplet ejection point detection unit 724 that reads an image, and a control unit 722 that controls them.

The supply unit 712 includes a magazine 730, a heating drum 732, and a cutter 734.
The magazine 730 stores a roll-shaped recording medium P. At the time of image drawing, the recording medium P is supplied from the magazine 730 to the heating drum 732.
The heating drum 732 is arranged on the downstream side of the magazine 730 in the conveyance path of the recording medium P, and the recording medium P sent out from the magazine 730 is bent in a direction opposite to the direction stored in the magazine 730. Heat in state.
By heating the recording medium P by the heating drum 732, the winding habit attached to the recording medium P is removed while being stored in the magazine 730. That is, the heating drum 732 performs a decurling process on the recording medium P.
At this time, it is preferable to control the heating temperature so that the recording medium P is curled outwardly on the printing surface.

The cutter 734 includes a fixed blade 734A having a length equal to or larger than the conveyance path width of the recording medium P and a round blade 734B that moves along the fixed blade 734A. The round blade 734b is disposed on the surface, and the fixed blade 734A is disposed on the opposite surface across the conveyance path.
The cutter 734 cuts the recording medium P supplied through the heating drum 732 into a desired size.

  Here, in this embodiment, the supply unit has one magazine. However, the present invention is not limited to this. For example, a plurality of magazines containing recording media having different paper width, paper quality, and type may be arranged. Also, a cassette in which a large number of recording media that have been cut in advance to a predetermined length can be used instead of or in addition to the magazine. When only the recording medium P that has been cut to a predetermined length is used as the recording medium P, the above-described heating roller and cutter are not necessarily provided.

  Further, when a plurality of magazines and / or cassettes are used and a plurality of types of recording paper can be used, an information recording body such as a bar code or a wireless tag in which the paper type information is recorded is used as the magazine and / or cassette. Attach and read the information of the information recording medium with a predetermined reader to automatically determine the type of paper to be used, and perform ink ejection control to realize appropriate ink ejection according to the type of paper Preferably it is done.

  The conveyance unit 714 includes an adsorption belt conveyance unit 736, an adsorption chamber 739, a fan 740, a belt cleaning unit 742, and a heating fan 744. The recording medium P that has been decurled by the supply unit 712 and cut to a predetermined length is provided. The drawing position is conveyed to a position where an image is drawn by a drawing unit 716 described later.

The suction belt conveyance unit 736 is disposed on the downstream side of the cutter 734 in the conveyance path of the recording medium P, and includes a roller 737a, a roller 737b, and a belt 738.
The belt 738 is an endless belt having a width that is wider than the width of the recording medium P, and is stretched between a roller 737a and a roller 737b. The belt 738 has a plurality of suction holes (not shown) formed on the belt surface.
Further, at least an image drawing (printing) position of the suction belt conveyance unit 736, that is, a nozzle surface of a recording head unit 750 described later of the drawing unit 716, and an image detection position, that is, a sensor of a droplet ejection point detecting unit 724 described later. The portion facing the surface is held horizontally (flat) with respect to the nozzle surface and the sensor surface.
At least one of the rollers 737a and 737b around which the belt 738 is wound is connected to a motor (not shown), and the power of the motor is transmitted to the belt 738 via at least one of the rollers 737a and 737b. Is driven clockwise in FIG. 22, and the recording medium P held on the belt 738 is conveyed from left to right in FIG.

  Here, the transport means for the recording medium P is not particularly limited, and a roller / nip transport mechanism can be used instead of the suction belt transport section 736. However, when the drawing area is conveyed by the roller / nip, the roller contacts the printing surface immediately after printing, so that there is a problem that the image is likely to spread. Therefore, the printing area does not contact the image surface as in the present embodiment. Adsorption belt conveyance is preferred.

The suction chamber 739 is provided inside the belt 738 at a position facing a nozzle surface of a recording head unit 750 (to be described later) of the drawing unit 716 and a sensor surface of the droplet ejection point detection unit 724. The fan 740 is connected to the adsorption chamber 739. By sucking the suction chamber 739 with the fan 740 and making it a negative pressure, the recording medium P on the belt 738 is sucked and held on the belt 738.
By adsorbing the recording medium P to the belt, the recording medium P can be stably held.

The belt cleaning unit 742 is disposed outside the belt 738, that is, on the side facing the ring-shaped outer peripheral surface, and at a position away from the conveyance path of the recording medium P. That is, the belt 738 passes through the drawing unit 716, discharges the recording medium P to a pressure roller 754 described later, and then passes through a position facing the belt cleaning unit 742.
The belt cleaning unit 742 removes ink attached on the belt 738 by performing borderless printing or the like. Examples of the belt cleaning unit 742 include a method of niping a brush / roll, a water absorbing roll, an air blow method of blowing clean air, or a combination thereof. In the case where the cleaning roll is nipped, the cleaning effect is great if the belt linear velocity and the roller linear velocity are changed.

The heating fan 744 is disposed outside the belt 738 and on the upstream side of a recording head unit 750 described later of the drawing unit 716 on the conveyance path of the recording medium P.
The heating fan 744 blows heated air on the recording medium P before drawing to heat the recording medium P. By heating the recording medium P immediately before drawing, the ink is easily dried after landing.

  The drawing unit 716 includes a recording head unit 750 that draws (prints) an image, and an ink storage / loading unit 752 that supplies ink to the recording head unit 750.

The recording head unit 750 includes recording heads 750K, 750C, 750M, and 750Y, and is disposed to face the surface of the belt 738 on which the recording medium P is placed.
The recording heads 750K, 750C, 750M, and 750Y are piezo-type inkjet heads that discharge black (K), cyan (C), magenta (M), and yellow (Y) ink from the discharge unit, respectively. The recording heads 750K, 750C, 750M, and 750Y are arranged in the order closer to the heating fan 744 on the downstream side in the transport direction of the recording medium P from the heating fan 744, facing the surface on which the recording medium P of 738 is placed. Arranged in order.
Further, as shown in FIG. 23, the recording heads 750K, 750C, 750M, and 750Y include a plurality of recording heads in a region where the width in the direction orthogonal to the conveyance direction of the recording medium P exceeds the maximum width of the recording medium P to be conveyed. This is a full-line type ink jet head in which ejection portions (nozzles) are arranged in a line. Since the configuration around the ejection section of the recording heads 750K, 750C, 750M, and 750Y is the same as that of the recording heads 136Y, 136M, 136C, and 136K, detailed description thereof is omitted.
In addition, a color image can be formed on the recording medium P by ejecting the color inks from the recording heads 750K, 750C, 750M, and 750Y while transporting the recording medium P.

Here, in this embodiment, the recording head unit has a configuration of KCMY standard colors (four colors), but the combination of ink colors and the number of colors is not limited to this embodiment, and for example, light ink, dark ink May be added. More specifically, it is possible to add a recording head that discharges light ink such as light cyan and light magenta.
Further, the recording head unit can be used only as a recording head that discharges K (black) ink, that is, a monochrome recording head unit, and can be used as an image drawing apparatus that draws a monochrome image.

The ink storage / loading unit 752 includes an ink supply tank that stores ink of colors corresponding to the recording heads 750K, 750C, 750M, and 750Y.
As the ink supply tank, for example, a system that replenishes ink into a tank from a replenishing port (not shown) or a cartridge system that replaces the entire tank when the ink remaining amount is low can be used.
Each ink supply tank of the ink storage / loading unit 752 communicates with each recording head 750K, 750C, 750M, 750Y via a pipe line (not shown), and supplies ink to each recording head 750K, 750C, 750M, 750Y. To do.

Here, the ink storage / loading unit 752 includes notifying means (display means, warning sound generating means, etc.) for notifying when the ink remaining amount is low, and a mechanism for preventing erroneous loading between colors. It is preferable to have.
Further, when the ink type is changed according to the intended use, it is preferable to use a cartridge system. In addition, it is preferable that the ink type information is identified by a barcode or the like, and ejection control is performed according to the ink type.

The heating / pressurizing unit 718 includes a post-drying unit 746 and a pressure roller pair 754, and heats and presses the recording medium P on which an image is drawn by the drawing unit 716, thereby drying and fixing the image portion. .
The post-drying unit 746 is disposed on the downstream side of the recording head unit 750 in the conveyance path of the recording medium P and at a position facing the belt 738. The post-drying unit 746 is a heating fan or the like, blows hot air on the image surface of the recording medium P, and dries the drawn image.
Here, the post-drying section 746 is preferably blown with hot air using a heating fan.
By drying the ink in the image area on the recording medium with the heating fan, the ink can be dried without contacting the image area. As a result, it is possible to prevent image defects and image smearing from occurring on the image drawn on the recording medium P.

Further, the pressure roller pair 754 is disposed on the downstream side of the post-drying unit 746 in the conveyance path of the recording medium P. The pressure roller pair 754 sandwiches and conveys the recording medium P separated from the belt 738 after passing through the post-drying unit 746.
The pressure roller pair 754 is a means for controlling the glossiness of the image surface. The pressure roller pair 754 has a predetermined surface uneven shape while heating the image surface of the recording medium P conveyed by the suction belt conveyance unit 736. Pressure is applied by a roller 754 to transfer the uneven shape to the image surface.

  In addition, when printing on porous paper with dye-based ink, it is possible to prevent contact with things that cause destruction of dye molecules, such as ozone, by blocking the paper holes by pressurization. The weather resistance of can be improved.

Further, in the inkjet drawing apparatus 710, a cutter (second cutter) 756 is disposed on the downstream side of the heating / pressurizing unit 718 in the conveyance path of the recording medium P.
The cutter 756 includes a fixed blade 756A and a round blade 756B. When a normal image and an image for detecting displacement are formed on the recording medium P, a normal image portion and an image portion for detecting displacement are recorded. Disconnect.

The discharge unit 720 includes a first discharge unit 758 </ b> A and a second discharge unit 758 </ b> B, and is disposed on the downstream side of the cutter 756 in the conveyance direction of the recording medium P. The discharge unit 720 discharges the recording medium P on which the image is fixed by the heating / pressurizing unit 718.
Here, in the present embodiment, according to the image recorded on the recording medium P, the sorting unit (not shown) switches the discharging unit that discharges the recording medium P, and a normal image is drawn on the first discharging unit 758A. The recorded medium is discharged, and the second discharged portion 758B is discharged with the recording medium on which the image used for detecting the misregistration is drawn or an unnecessary recorded medium.

  Further, it is preferable that the discharge unit 720 is provided with a sorter for collecting images according to orders.

  As in the present embodiment, it is preferable to provide two discharge units so that the discharge unit can be selected according to the purpose. However, the present invention is not limited to this. The medium may be discharged from one discharge unit. Moreover, you may provide three or more discharge parts.

  Next, the control unit 722 is configured to convey, heat, draw, and misalign the recording medium by the supply unit 712, the conveyance unit 714, the drawing unit 716, the heating / pressurizing unit 718, the discharge unit 720, and the droplet ejection point detection unit 724. Control detection etc. The configuration of the control unit 722 will be described in detail later.

  The droplet ejection point detection unit 724 is disposed at a position facing the outside (outer peripheral surface) of the belt 738 and between the recording head unit 750 and the post-drying unit 746. The droplet ejection point detection unit 724 has an image sensor (line sensor or the like) for imaging the droplet ejection result of the drawing unit 716, and the size (size) of the droplet ejection point from the droplet ejection image read by the image sensor. Detecting the displacement of the droplet ejection position.

  The droplet ejection point detection unit 724 of the present embodiment is configured by a line sensor having a light receiving element array wider than the ink ejection width (image recording width) by the recording heads 750K, 750C, 750M, and 750Y. The line sensor includes an R sensor array in which photoelectric conversion elements (pixels) provided with a red (R) color filter are arranged in a line, a G sensor array provided with a green (G) color filter, And a color separation line CCD sensor including a B sensor array provided with a blue (B) color filter. Instead of the line sensor, an area sensor in which the light receiving elements are two-dimensionally arranged can be used.

  The droplet ejection point detection unit 724 reads test patterns drawn by the recording heads 750K, 750C, 750M, and 750Y for each color, and detects the droplet ejection point size and the droplet ejection point position deviation of each recording head.

FIG. 24 is a principal block diagram showing the system configuration of the control unit 722 of the inkjet drawing apparatus 710.
The control unit 722 includes a communication interface 780, a system controller 782, an image memory 784, a motor driver 786, a heater driver 788, a print control unit 790, an image buffer memory 792, a head driver 794, and the like, and as described above, the supply unit 712. , Conveyance unit 714, drawing unit 716, heating / pressurizing unit 718, discharge unit 720, droplet ejection point detection unit 724 controls the conveyance, heating, drawing, droplet ejection point size detection and the like of the recording medium P.

  The system controller 782 is a control unit that controls the communication interface 780, the image memory 784, the motor driver 786, the heater driver 788, and the like. The system controller 782 includes a central processing unit (CPU) and its peripheral circuits, and performs communication control with the host computer 796, read / write control of the image memory 784, and the like, and a motor 798 and a heater 799 for the transport system. A control signal for controlling is generated.

  The communication interface 780 receives image data sent from the host computer 796 and sends it to the system controller 782. As the communication interface 780, a serial interface such as USB, IEEE 1394, Ethernet (registered trademark), a wireless network, or a parallel interface such as Centronics can be used. Furthermore, a buffer memory for speeding up communication may be installed.

The image memory 784 is a storage unit that temporarily stores an image input via the communication interface 780, and data is read and written through the system controller 782. The image memory 784 is not limited to a memory composed of semiconductor elements, and a magnetic medium such as a hard disk may be used.
Image data sent from the host computer 796 is taken into the inkjet drawing apparatus 710 via the communication interface 780 and stored in the image memory 784 via the system controller 782.

The motor driver 786 is a driver (drive circuit) that drives the motor 798 in accordance with an instruction from the system controller 782.
The heater driver 788 is a driver that drives the heater 799 such as the post-drying unit 746 in accordance with an instruction from the system controller 782.

  The print control unit 790 has a signal processing function for performing various processes such as processing and correction for generating a print control signal from image data in the image memory 784 under the control of the system controller 782, and the generated print The control unit supplies a control signal (print data) to the head driver 794. The print control unit 790 performs necessary signal processing, and controls the ejection amount and ejection timing of the ink droplets of the recording head 750 via the head driver 794 based on the image data. Thereby, a desired dot size and dot arrangement are realized.

  The print control unit 790 includes an image buffer memory 792, and image data, parameters, and other data are temporarily stored in the image buffer memory 792 when image data is processed in the print control unit 790. In FIG. 24, the image buffer memory 792 is shown in a form associated with the print control unit 790, but it can also be used as the image memory 784. Also possible is an aspect in which the print control unit 790 and the system controller 782 are integrated to form a single processor.

  The head driver 794 drives the actuators of the ejection units of the recording heads 750K, 750C, 750M, and 750Y of the respective colors based on the image (printing) data given from the print control unit 790. The head driver 794 may include a feedback control system for keeping the head driving conditions constant.

Next, a method for creating a print or printed matter using the inkjet recording apparatus 710 will be described.
The recording medium P supplied from the magazine 730 of the supply unit 712 is decurled by the heating drum 732 and flattened. Thereafter, the sheet is cut into a predetermined length by the cutter 734 and then supplied to the transport unit 714.
The recording medium P supplied to the transport unit 714 is placed on the belt 738 of the suction belt transport unit 736 and transported as the belt 738 rotates.
The recording medium P transported by the suction belt transport unit 736 passes through a position facing the heating fan 744 and is heated to a predetermined temperature, and then passes through a position facing the recording head unit 750 and on the surface thereof. Each recording head ejects ink droplets in the order of K, C, M, and Y, and an image is formed on the recording medium P. When the recording medium P passes through a position facing the recording head unit 750, the recording medium P is sucked by the suction chamber 739, and the distance between the recording medium P and the recording head unit 750 is constant.
The recording medium P on which the image is formed by the recording head unit 750 is further conveyed by the belt 738, passes through a position facing the post-drying unit 746, and the image unit formed of ink is dried and pressurized. After being fixed by the roller 754, it is discharged from the first discharge portion 758A.

  The ink jet drawing apparatus 710 draws (records) an image on the recording medium P in this way, and produces a print or printed matter.

Further, since the ink jet drawing apparatus 710 of the present embodiment also uses a full line type ink jet head as a recording head, the ink droplet ejection points ejected from the respective ejection units are the same as in the digital label printing apparatus 100. If the size is different from the desired size, streaks and unevenness are caused. Similarly, the misalignment of the droplet ejection point causes streaks and unevenness.
On the other hand, in the ink jet drawing apparatus 710, the droplet ejection point detector 724 is used to detect the droplet ejection point size in the same manner as the digital label printing apparatus 100 described above. By detecting the dot size, and further detecting the droplet ejection point position deviation, correction based on the detected droplet ejection point size and droplet ejection point position deviation eliminates streaking and unevenness. A high-quality image can be formed.
In addition, a method for detecting the size of the droplet ejection point and a method for detecting a positional deviation of the droplet ejection point, that is, a method for forming an image for detection, a method for detecting the droplet ejection point, a method for detecting the droplet ejection point, and a droplet ejection point size. The method of calculating the droplet ejection point and the method of calculating the droplet ejection point interval are the same as those in the case of the above-described digital label printing apparatus in the ink jet drawing apparatus of the present embodiment, so that the description thereof is omitted.

  Hereinafter, an active light source suitable when an actinic ray curable ink is used as a recording medium and ink that can be used in an ink jet drawing apparatus and a digital label printing apparatus that can be used in the droplet ejection spot size detection method of the present invention, and A suitable ink will be described.

  Hereinafter, an active light source suitable when an actinic ray curable ink is used as a recording medium and ink that can be used in an ink jet drawing apparatus and a digital label printing apparatus that can be used in the droplet ejection spot size detection method of the present invention, and A suitable ink will be described.

Here, the recording medium is not particularly limited, and papers such as ordinary uncoated paper and coated paper, various non-absorbing resin materials used for so-called soft packaging, or resin films obtained by forming the resin film into a film shape. Examples of various plastic films that can be used include PET film, OPS film, OPP film, ONy film, PVC film, PE film, and TAC film. In addition, examples of the plastic that can be used as a recording medium material include polycarbonate, acrylic resin, ABS, polyacetal, PVA, and rubbers. Metals and glasses can also be used as a recording medium. A surface-treated support serving as a printing plate substrate is used as the recording medium, and an image is formed on the surface of the support with ink-repellent ink. It can also be formed to form a printing plate.
In the ink composition, when a material with low thermal shrinkage at the time of curing is selected, the adhesive property between the cured ink composition and the recording medium is excellent. Films that are easily curled and deformed, such as heat-shrinkable PET film, OPS film, OPP film, ONy film, PVC film, etc., have the advantage that a high-definition image can be formed.

In the above embodiment, ultraviolet curable ink and ultraviolet curable transparent liquid are used as the ink and the transparent liquid, and the ultraviolet light source is used as the light source for curing the ink and the liquid. However, the present invention is not limited to this. However, various active energy curable inks and active energy curable transparent liquids can be used as the ink, and a light source that irradiates active energy is used as a light source for curing the ink and the transparent liquid. it can.
Here, the “active energy” as used in the present invention is not particularly limited as long as it can impart energy capable of generating a starting species in the ink and the transparent liquid by the irradiation, and is broadly expressed by α rays. , Γ rays, X rays, ultraviolet rays, visible rays, electron beams, and the like. Among these, from the viewpoints of curing sensitivity and device availability, ultraviolet rays and electron beams are preferable, and ultraviolet rays are particularly preferable. Therefore, the active energy curable ink and the active energy curable transparent liquid are preferably inks and transparent liquids that can be cured by irradiation with ultraviolet rays.

  Hereinafter, the active energy curable ink and the transparent liquid that can be suitably used in the ink jet drawing apparatus using the active energy curable ink as in the above-described embodiment in the ink jet drawing apparatus using the droplet ejection spot size detection method of the present invention. The active energy for curing the ink will be described in detail. The active energy type transparent liquid is the same as the active energy curable ink except that it does not have a coloring material. Therefore, the active energy type ink will be mainly described below.

The peak wavelength of the active energy is, for example, 200 to 650 nm, preferably 300 to 450 nm, more preferably 350, although it depends on the absorption characteristics of the sensitizing dye in the ink (hereinafter also referred to as “ink composition”). It is suitable that it is ˜450 nm. In addition, the (a) electron transfer start system of the ink of the present invention has sufficient sensitivity even with low output active energy. Therefore, the output of active energy is, for example, 2,000 mJ / cm ² or less, preferably 10 to 2,000 mJ / cm ² , more preferably 20 to 1,000 mJ / cm ² , and still more preferably 50 to 800 mJ. An irradiation energy of / cm ² is appropriate. The active energy exposure surface illuminance (the maximum illuminance of the surface of the recording medium) is, for example, 10 to 2,000 mW / cm ^2, preferably, suitably be irradiated at 20 to 1,000 mW / cm ² It is.
Particularly, in the ink jet recording apparatus used in the present invention, the active energy irradiation is an ultraviolet ray having an emission wavelength peak of 390 to 420 nm and a maximum illuminance on the surface of the recording medium of 10 to 1,000 mW / cm ^2. Irradiation from a light emitting diode that generates

In the ink jet drawing apparatus using the present invention, the active energy is applied to the ink composition ejected on the recording medium, for example, for 0.01 to 120 seconds, preferably 0.1 to 90 seconds. Is appropriate.
Further, in the ink jet drawing apparatus using the present invention, the ink is heated to a constant temperature, and the time from the ink landing on the recording medium to the irradiation of the active energy is set to 0.01 to 0.5 seconds. Is preferably 0.02 to 0.3 seconds, and more preferably 0.03 to 0.15 seconds. Thus, by controlling the time from the landing of the ink to the recording medium to the irradiation of the active energy to an extremely short time, it is possible to prevent the landed ink from spreading before curing.

  In order to obtain a color image using the ink jet recording apparatus using the present invention, it is preferable to superimpose in order from the color with the lowest brightness. By overlapping in this way, the active energy can easily reach the lower ink, and good curing sensitivity, reduction of residual monomers, reduction of odor, and improvement of adhesion can be expected. In addition, although irradiation with active energy can be performed by injecting all the colors and exposing them together, exposure for each color is preferable from the viewpoint of promoting curing.

  In addition, as described above, since the active energy curable ink desirably has a constant temperature for the ejected ink, temperature control by heat insulation and heating is performed from the ink supply tank to the recording head (inkjet head) portion. It is preferable to carry out. The recording head unit to be heated is preferably thermally shielded or insulated so that the apparatus main body is not affected by the temperature of the outside air. In order to shorten the printer start-up time required for heating or to reduce the loss of heat energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.

  Further, mercury lamps and gas / solid lasers are mainly used as active energy sources, and mercury lamps and metal halide lamps are widely known as UV irradiation parts for curing UV photocurable ink. Yes. Furthermore, replacement with a GaN-based semiconductor ultraviolet light emitting device is very useful industrially and environmentally. Furthermore, LED (UV-LED) and LD (UV-LD) are small, have a long lifetime, high efficiency, and low cost, and can be suitably used as an active energy curable inkjet radiation source (active light source).

  Further, as described above, a light emitting diode (LED) and a laser diode (LD) can be used as the active energy source. In particular, when an ultraviolet light source is required, an ultraviolet LED and an ultraviolet LD can be used. For example, Nichia Corporation has introduced a purple LED whose main emission spectrum has a wavelength between 365 nm and 420 nm. Furthermore, when shorter wavelengths are required, US Pat. No. 6,084,250 discloses an LED that can emit active energy centered between 300 nm and 370 nm. Other ultraviolet LEDs are also available and can radiate radiation in different ultraviolet bands. A particularly preferable active energy source in the present invention is a UV-LED, and a UV-LED having a peak wavelength of 350 to 420 nm is particularly preferable.

Below, each component used for the active energy curable ink which can be used suitably by this invention is demonstrated one by one.
Examples of the ink that can be suitably used in the present invention and can be cured by irradiation with active energy include a cationic polymerization ink composition, a radical polymerization ink composition, and a water-based ink composition. These compositions will be described in detail below.

(Cationically-polymerized ink composition)
The cationic polymerization-type ink composition contains (a) a cationic polymerizable compound, (b) a compound that generates an acid upon irradiation with active energy, and (c) a colorant. If desired, it may further contain an ultraviolet absorber, a sensitizer, an antioxidant, an antifading agent, a conductive salt, a solvent, a polymer compound, a surfactant and the like.
Hereafter, each component used for a cationic polymerization type ink composition is demonstrated one by one.

[(A) Cationic polymerizable compound]
The (a) cationic polymerizable compound used in the active energy curable ink is a compound that causes a polymerization reaction by an acid generated from a compound that generates an acid upon irradiation with active energy (b), which will be described later, and is cured. There is no restriction | limiting, The various well-known cationically polymerizable monomer known as a photocationic polymerizable monomer can be used. Examples of the cationic polymerizable monomer include various publications such as JP-A-6-9714, JP-A-2001-31892, JP-A-2001-40068, JP-A-2001-55507, JP-A-2001-310938, JP-A-2001-310937, and JP-A-2001-220526. Examples thereof include epoxy compounds, vinyl ether compounds, oxetane compounds and the like.

Examples of the epoxy compound include aromatic epoxides, alicyclic epoxides, and aliphatic epoxides.
Aromatic epoxides include di- or polyglycidyl ethers produced by the reaction of polyphenols having at least one aromatic nucleus or their alkylene oxide adducts and epichlorohydrin, such as bisphenol A or its alkylene oxides. Examples thereof include di- or polyglycidyl ethers of adducts, di- or polyglycidyl ethers of hydrogenated bisphenol A or its alkylene oxide adducts, and novolak-type epoxy resins. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

  As the alicyclic epoxide, cyclohexene oxide obtained by epoxidizing a compound having at least one cycloalkane ring such as cyclohexene or cyclopentene ring with a suitable oxidizing agent such as hydrogen peroxide or peracid. Or a cyclopentene oxide containing compound is mentioned preferably.

  Examples of the aliphatic epoxide include dihydric polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. Typical examples include diglycidyl ether of ethylene glycol, diglycidyl ether of propylene glycol or diglycidyl ether of alkylene glycol such as diglycidyl ether of 1,6-hexanediol, di- or tri- or di- or tri-glycol or adducts thereof. Polyglycidyl ether of polyhydric alcohol such as glycidyl ether, diglycidyl ether of polyethylene glycol or alkylene oxide adduct thereof, diglycidyl ether of polyalkylene glycol represented by diglycidyl ether of polypropylene glycol or alkylene oxide adduct thereof, etc. Can be mentioned. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

The epoxy compound may be monofunctional or polyfunctional.
Examples of monofunctional epoxy compounds that can be suitably used for the active energy curable ink include, for example, phenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, 1,2-butylene oxide, 1,3-butadiene monooxide, 1,2-epoxydodecane, epichlorohydrin, 1,2-epoxydecane, styrene oxide, cyclohexene oxide, 3-methacryloyloxymethylcyclohexene oxide, 3- Examples include acryloyloxymethylcyclohexene oxide and 3-vinylcyclohexene oxide.

  Examples of polyfunctional epoxy compounds include, for example, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, brominated bisphenol A diglycidyl ether, brominated bisphenol F diglycidyl ether, and brominated bisphenol. S diglycidyl ether, epoxy novolac resin, hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, hydrogenated bisphenol S diglycidyl ether, 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxy 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexane-meta-dioxane, bis (3,4-epoxy Hexylmethyl) adipate, vinylcyclohexene oxide, 4-vinylepoxycyclohexane, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 3,4-epoxy-6-methylcyclohexyl-3 ', 4'-epoxy- 6'-methylcyclohexanecarboxylate, methylenebis (3,4-epoxycyclohexane), dicyclopentadiene diepoxide, ethylene glycol di (3,4-epoxycyclohexylmethyl) ether, ethylenebis (3,4-epoxycyclohexanecarboxylate) ), Dioctyl epoxyhexahydrophthalate, di-2-ethylhexyl epoxyhexahydrophthalate, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl Ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ethers, 1,1,3-tetradecadiene dioxide, limonene dioxide, 1,2,7,8 -Diepoxyoctane, 1,2,5,6-diepoxycyclooctane and the like.

  Among these epoxy compounds, aromatic epoxides and alicyclic epoxides are preferable from the viewpoint of excellent curing speed, and alicyclic epoxides are particularly preferable.

  Examples of the vinyl ether compound include ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, Di- or trivinyl ether compounds such as methylolpropane trivinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexane dimethanol monovinyl ether, n-propyl Pills vinyl ether, isopropyl vinyl ether, isopropenyl ether -O- propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, and octadecyl vinyl ether.

The vinyl ether compound may be monofunctional or polyfunctional.
Specifically, examples of monofunctional vinyl ethers include, for example, methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, n-butyl vinyl ether, t-butyl vinyl ether, 2-ethylhexyl vinyl ether, n-nonyl vinyl ether, lauryl vinyl ether, cyclohexyl vinyl ether, Cyclohexylmethyl vinyl ether, 4-methylcyclohexyl methyl vinyl ether, benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenoxyethyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, butoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether, ethoxyethoxyethyl vinyl ether , Methoxypolyethyleneglycol Vinyl ether, tetrahydrofurfuryl vinyl ether, 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxymethylcyclohexyl methyl vinyl ether, diethylene glycol monovinyl ether, polyethylene glycol vinyl ether, chloroethyl vinyl ether, chlorobutyl vinyl ether, Examples include chloroethoxyethyl vinyl ether, phenylethyl vinyl ether, phenoxypolyethylene glycol vinyl ether, and the like.

  Examples of polyfunctional vinyl ethers include ethylene glycol divinyl ether, diethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, butylene glycol divinyl ether, hexanediol divinyl ether, bisphenol A alkylene oxide divinyl ether, and bisphenol F. Divinyl ethers such as alkylene oxide divinyl ether; trimethylolethane trivinyl ether, trimethylolpropane trivinyl ether, ditrimethylolpropane tetravinyl ether, glycerin trivinyl ether, pentaerythritol tetravinyl ether, dipentaerythritol pentavinyl ether, dipentaerythritol Hexavinyl ether, ethylene oxide-added trimethylolpropane trivinyl ether, propylene oxide-added trimethylolpropane trivinyl ether, ethylene oxide-added ditrimethylolpropane tetravinyl ether, propylene oxide-added ditrimethylolpropane tetravinyl ether, ethylene oxide-added pentaerythritol tetravinyl ether, propylene oxide addition Examples thereof include polyfunctional vinyl ethers such as pentaerythritol tetravinyl ether, ethylene oxide-added dipentaerythritol hexavinyl ether, and propylene oxide-added dipentaerythritol hexavinyl ether.

  As the vinyl ether compound, a di- or trivinyl ether compound is preferable from the viewpoints of curability, adhesion to a recording medium, surface hardness of the formed image, and the like, and a divinyl ether compound is particularly preferable.

The oxetane compound in the present invention refers to a compound having an oxetane ring, and a known oxetane compound is arbitrarily selected and used as described in JP-A Nos. 2001-220526, 2001-310937, and 2003-341217. it can.
As the compound having an oxetane ring, a compound having 1 to 4 oxetane rings in the structure is preferably used. By using such a compound, it becomes easy to maintain the viscosity of the ink composition in a favorable handling property range, and high adhesion between the cured ink composition and the recording medium is obtained. be able to.

The compound having such an oxetane ring is described in detail in the above-mentioned JP-A No. 2003-341217, paragraph numbers [0021] to [0084], and the compounds described herein can be suitably used in the present invention.
Among the oxetane compounds used in the present invention, it is preferable to use a compound having one oxetane ring from the viewpoint of the viscosity and tackiness of the ink.

In the active energy curable ink, these cationic polymerizable compounds may be used alone or in combination of two or more. From the viewpoint of effectively suppressing shrinkage during ink curing. It is preferable to use a vinyl ether compound in combination with at least one compound selected from an oxetane compound and an epoxy compound.
The content of the (a) cationic polymerizable compound in the ink is suitably 10 to 95% by mass, preferably 30 to 90% by mass, more preferably 50 to 85% by mass, based on the total solid content of the composition. Range.

[(B) Compound that generates acid upon irradiation with active energy]
The active energy curable ink that can be used in the present invention contains a compound that generates an acid upon irradiation with active energy (hereinafter, appropriately referred to as “photo acid generator”).
Examples of the photoacid generator that can be used in the present invention include photoinitiators for photocationic polymerization, photoinitiators for photoradical polymerization, photodecolorants for dyes, photochromic agents, and light used for microresists. (400-200 nm ultraviolet rays, far ultraviolet rays, particularly preferably g-line, h-line, i-line, KrF excimer laser beam), ArF excimer laser beam, electron beam, X-ray, molecular beam, ion beam, etc. A compound capable of generating can be appropriately selected and used.

  As such a photoacid generator, for example, an onium salt such as a diazonium salt, an ammonium salt, a phosphonium salt, an iodonium salt, a sulfonium salt, a selenonium salt, an arsonium salt, which decomposes upon irradiation with active energy to generate an acid, Organic halogen compounds, organic metal / organic halides, photoacid generators having an o-nitrobenzyl type protecting group, compounds that generate photosulfonic acids by photolysis, such as iminosulfonates, disulfone compounds, diazoketo A sulfone and a diazo disulfone compound can be mentioned.

  As the photoacid generator, oxazole derivatives and s-triazine derivatives described in JP-A No. 2002-122994, paragraphs [0029] to [0030] are also preferably used. Furthermore, onium salt compounds and sulfonate compounds exemplified in JP-A-2002-122994, paragraph numbers [0037] to [0063] can also be suitably used as the photoacid generator.

(B) A photo-acid generator can be used individually by 1 type or in combination of 2 or more types.
The content of the (b) photoacid generator in the ink composition is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, and still more preferably in terms of the total solid content of the ink composition. Is 1-7 mass%.

[(C) Colorant]
The active energy curable ink can form a visible image by adding a colorant. For example, when forming an image area of a lithographic printing plate, it is not always necessary to add it, but it is also preferable to use a colorant from the viewpoint of plate inspection of the obtained lithographic printing plate.
There is no restriction | limiting in particular in the coloring agent which can be used here, According to a use, well-known various color materials and (pigment, dye) can be selected suitably, and can be used. For example, when forming an image excellent in weather resistance, a pigment is preferable. As the dye, both water-soluble dyes and oil-soluble dyes can be used, but oil-soluble dyes are preferred.

[Pigment]
The pigments preferably used for the active energy curable ink will be described.
The pigment is not particularly limited, and all commercially available organic and inorganic pigments or pigments dispersed in an insoluble resin or the like as a dispersion medium, or the resin is grafted onto the pigment surface Can be used. Moreover, what dye | stained the resin particle with dye can be used.
Examples of these pigments include, for example, “Pigment Dictionary” (2000), edited by Seijiro Ito. Herbst, K.M. Hunger “Industrial Organic Pigments”, JP 2002-12607 A, JP 2002-188025 A, JP 2003-26978 A, and JP 2003-342503 A3.

  Specific examples of organic pigments and inorganic pigments that can be used in the active energy curable ink include C.I. I. Pigment Yellow 1 (Fast Yellow G etc.), C.I. I. A monoazo pigment such as C.I. Pigment Yellow 74; I. Pigment Yellow 12 (disaji yellow AAA, etc.), C.I. I. Disazo pigments such as C.I. Pigment Yellow 17; I. Non-benzidine type azo pigments such as CI Pigment Yellow 180; I. Azo lake pigments such as C.I. Pigment Yellow 100 (eg Tartrazine Yellow Lake); I. Condensed azo pigments such as CI Pigment Yellow 95 (Condensed Azo Yellow GR, etc.); I. Acidic dye lake pigments such as C.I. Pigment Yellow 115 (such as quinoline yellow lake); I. Basic dye lake pigments such as CI Pigment Yellow 18 (Thioflavin Lake, etc.), anthraquinone pigments such as Flavantron Yellow (Y-24), isoindolinone pigments such as Isoindolinone Yellow 3RLT (Y-110), and quinophthalone yellow Quinophthalone pigments such as (Y-138), isoindoline pigments such as isoindoline yellow (Y-139), C.I. I. Nitroso pigments such as C.I. Pigment Yellow 153 (nickel nitroso yellow, etc.); I. And metal complex salt azomethine pigments such as CI Pigment Yellow 117 (copper azomethine yellow, etc.).

  C. As a thing which exhibits red or magenta color, C.I. I. Monoazo pigments such as CI Pigment Red 3 (Toluidine Red, etc.); I. Disazo pigments such as C.I. Pigment Red 38 (Pyrazolone Red B, etc.); I. Pigment Red 53: 1 (Lake Red C, etc.) and C.I. I. Azo lake pigments such as C.I. Pigment Red 57: 1 (Brilliant Carmine 6B); I. Condensed azo pigments such as C.I. Pigment Red 144 (condensed azo red BR, etc.); I. Acidic dye lake pigments such as C.I. Pigment Red 174 (Phloxine B Lake, etc.); I. Basic dye lake pigments such as C.I. Pigment Red 81 (Rhodamine 6G 'lake, etc.); I. Anthraquinone pigments such as C.I. Pigment Red 177 (eg, dianthraquinonyl red); I. Thioindigo pigments such as C.I. Pigment Red 88 (Thioindigo Bordeaux, etc.); I. Perinone pigments such as C.I. Pigment Red 194 (perinone red, etc.); I. Perylene pigments such as C.I. Pigment Red 149 (perylene scarlet, etc.); I. Pigment violet 19 (unsubstituted quinacridone), C.I. I. Quinacridone pigments such as CI Pigment Red 122 (quinacridone magenta, etc.); I. Isoindolinone pigments such as CI Pigment Red 180 (isoindolinone red 2BLT, etc.); I. And alizarin lake pigments such as CI Pigment Red 83 (Madder Lake, etc.).

  As a pigment exhibiting blue or cyan, C.I. I. Disazo pigments such as C.I. Pigment Blue 25 (Dianisidine Blue, etc.); I. Phthalocyanine pigments such as C.I. Pigment Blue 15 (phthalocyanine blue, etc.); I. Acidic dye lake pigments such as C.I. Pigment Blue 24 (Peacock Blue Lake, etc.); I. Basic dye lake pigments such as C.I. Pigment Blue 1 (Viclotia Pure Blue BO Lake, etc.); I. Anthraquinone pigments such as C.I. Pigment Blue 60 (Indantron Blue, etc.); I. And alkali blue pigments such as CI Pigment Blue 18 (Alkali Blue V-5: 1).

As a pigment exhibiting green, C.I. I. Pigment green 7 (phthalocyanine green), C.I. I. Phthalocyanine pigments such as C.I. Pigment Green 36 (phthalocyanine green); I. And azo metal complex pigments such as CI Pigment Green 8 (Nitroso Green).
As a pigment exhibiting an orange color, C.I. I. An isoindoline pigment such as C.I. Pigment Orange 66 (isoindoline orange); I. And anthraquinone pigments such as CI Pigment Orange 51 (dichloropyrantron orange).

Examples of the black pigment include carbon black, titanium black, and aniline black.
Specific examples of the white pigment include basic lead carbonate (2PbCO ₃ Pb (OH) ₂ , so-called silver white), zinc oxide (ZnO, so-called zinc white), titanium oxide (TiO ₂ , so-called titanium white), Strontium titanate (SrTiO ₃ , so-called titanium strontium white) or the like can be used.

  Here, titanium oxide has a smaller specific gravity than other white pigments, a large refractive index, and is chemically and physically stable, so that it has a large hiding power and coloring power as a pigment. Excellent durability against other environments. Therefore, it is preferable to use titanium oxide as the white pigment. Of course, other white pigments (may be other than the listed white pigments) may be used as necessary.

For dispersing the pigment, for example, a dispersion device such as a ball mill, a sand mill, an attritor, a roll mill, a jet mill, a homogenizer, a paint shaker, a kneader, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, or a wet jet mill is used. be able to.
It is also possible to add a dispersant when dispersing the pigment. Examples of the dispersant include a hydroxyl group-containing carboxylic acid ester, a salt of a long-chain polyaminoamide and a high molecular weight acid ester, a salt of a high molecular weight polycarboxylic acid, a high molecular weight unsaturated acid ester, a high molecular weight copolymer, a modified polyacrylate, an aliphatic Examples thereof include polyvalent carboxylic acids, naphthalene sulfonic acid formalin condensates, polyoxyethylene alkyl phosphate esters, and pigment derivatives. It is also preferable to use a commercially available polymer dispersant such as the Solsperse series from Zeneca.
Moreover, it is also possible to use a synergist according to various pigments as a dispersion aid. These dispersants and dispersion aids are preferably added in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the pigment.

  In the active energy curable ink, as a dispersion medium for various components such as pigments, a solvent may be added, and the above-mentioned (a) cationic polymerizable compound which is a low molecular weight component without solvent is used as a dispersion medium. However, since the ink is applied to the recording medium and then cured, it is preferably solventless. This is because if the solvent remains in the cured ink image, the solvent resistance is deteriorated or a VOC (Volatile Organic Compound) problem of the remaining solvent occurs. From such a viewpoint, as the dispersion medium, (a) a cation polymerizable compound is used, and among them, it is preferable to select a cation polymerizable monomer having the lowest viscosity in terms of dispersion suitability and handling property of the ink composition. .

The average particle size of the pigment is preferably 0.02 to 4 μm, more preferably 0.02 to 2 μm, and more preferably 0.02 to 1.0 μm.
The selection of pigment, dispersant, dispersion medium, dispersion conditions, and filtration conditions are set so that the average particle diameter of the pigment particles is within the above-mentioned preferable range. By controlling the particle size, clogging of the head nozzle can be suppressed, and ink storage stability, ink transparency, and curing sensitivity can be maintained.

〔dye〕
The dye used for the active energy curable ink is preferably oil-soluble. Specifically, it means that the solubility in water at 25 ° C. (the mass of the dye dissolved in 100 g of water) is 1 g or less, preferably 0.5 g or less, more preferably 0.1 g or less. Therefore, a so-called water-insoluble oil-soluble dye is preferably used.

It is also preferable to introduce an oil-solubilizing group into the dye mother nucleus described above in order to dissolve the necessary amount of the dye used in the active energy curable ink in the ink.
As the oil-solubilizing group, long chain, branched alkyl group, long chain, branched alkoxy group, long chain, branched alkylthio group, long chain, branched alkylsulfonyl group, long chain, branched acyloxy group, long chain, branched alkoxycarbonyl group, Long chain, branched acyl group, long chain, branched acylamino group long chain, branched alkylsulfonylamino group, long chain, branched alkylaminosulfonyl group and these long chains, aryl groups containing branched substituents, aryloxy groups, aryloxycarbonyl Group, arylcarbonyloxy group, arylaminocarbonyl group, arylaminosulfonyl group, arylsulfonylamino group and the like.
In addition, for water-soluble dyes having carboxylic acid and sulfonic acid, long chain, branched alcohol, amine, phenol, aniline derivatives are used as oil-solubilizing alkoxycarbonyl groups, aryloxycarbonyl groups, alkylaminosulfonyl groups, A dye may be obtained by conversion to an arylaminosulfonyl group.

The oil-soluble dye preferably has a melting point of 200 ° C. or lower, more preferably has a melting point of 150 ° C. or lower, and still more preferably has a melting point of 100 ° C. or lower. By using an oil-soluble dye having a low melting point, the precipitation of pigment crystals in the ink is suppressed, and the storage stability of the ink is improved.
Further, it is desirable that the oxidation potential is noble (high) in order to improve fading, particularly resistance to oxidizing substances such as ozone and curing characteristics. For this reason, as the oil-soluble dye used in the present invention, those having an oxidation potential of 1.0 V (vs SCE) or more are preferably used. The oxidation potential is preferably higher, the oxidation potential is more preferably 1.1 V (vs SCE) or more, and particularly preferably 1.15 V (vs SCE) or more.

As the yellow dye, a compound having a structure represented by the general formula (Y-I) described in JP-A No. 2004-250483 is preferable.
Particularly preferred dyes are dyes represented by the general formulas (Y-II) to (Y-IV) described in paragraph [0034] of JP-A No. 2004-250483. And the compounds described in paragraph numbers [0060] to [0071] of JP-A-250483. The oil-soluble dye of the general formula (Y-I) described in the publication may be used not only for yellow but also for inks of any color such as black ink and red ink.

The magenta dye is preferably a compound having a structure represented by the general formulas (3) and (4) described in JP-A No. 2002-114930. Specific examples include paragraphs of JP-A No. 2002-114930. Examples include the compounds described in [0054] to [0073].
Particularly preferred dyes are azo dyes represented by the general formulas (M-1) to (M-2) described in paragraph numbers [0084] to [0122] of JP-A No. 2002-121414, and specific examples Examples thereof include compounds described in paragraph numbers [0123] to [0132] of JP-A No. 2002-121414. The oil-soluble dyes represented by the general formulas (3), (4) and (M-1) to (M-2) described in the publication are used not only for magenta but also for any color ink such as black ink and red ink. May be.

Examples of cyan dyes include dyes represented by formulas (I) to (IV) described in JP-A No. 2001-181547, and paragraphs [0063] to [0078] of JP-A No. 2002-121414. The dyes represented by the general formulas (IV-1) to (IV-4) are mentioned as preferable examples, and specific examples include paragraph numbers [0052] to [0066] of JP-A No. 2001-181547. Examples thereof include the compounds described in paragraph Nos. [0079] to [0081] of Kai 2002-121414.
Particularly preferred dyes are phthalocyanine dyes represented by general formulas (CI) and (C-II) described in paragraphs [0133] to [0196] of JP-A No. 2002-121414, A phthalocyanine dye represented by formula (C-II) is preferred. Specific examples thereof include the compounds described in JP-A No. 2002-121414, paragraph numbers [0198] to [0201]. The oil-soluble dyes of the formulas (I) to (IV), (IV-1) to (IV-4), (CI) and (C-II) are not only cyan but also black ink or green ink. The ink may be used for any color ink.

These colorants are preferably added in an amount of 1 to 20% by mass in terms of solid content, and more preferably 2 to 10% by mass.
In addition to the essential components described above, various additives can be used in combination with the active energy curable ink depending on the purpose. These optional components will be described.

[Ultraviolet absorber]
In the active energy curable ink, an ultraviolet absorber can be used from the viewpoint of improving the weather resistance of the obtained image and preventing discoloration.
Examples of the ultraviolet absorber are described in JP-A-58-185679, JP-A-61-190537, JP-A-2-782, JP-A-5-97075, JP-A-9-34057, and the like. Benzotriazole compounds, benzophenone compounds described in JP-A No. 46-2784, JP-A No. 5-194843, US Pat. No. 3,214,463, etc., JP-B Nos. 48-30492 and 56-21141 Cinnamic acid compounds described in JP-A-10-88106, JP-A-4-298503, JP-A-8-53427, JP-A-8-239368, JP-A-10-182621, JP The triazine compounds described in JP-A-8-501291, Research Disclosure No. Examples thereof include compounds described in No. 24239, compounds that emit ultraviolet light by absorbing ultraviolet rays typified by stilbene and benzoxazole compounds, so-called fluorescent brighteners, and the like.
The addition amount is appropriately selected according to the purpose, but is generally about 0.5 to 15% by mass in terms of solid content.

[Sensitizer]
If necessary, a sensitizer may be added to the active energy curable ink for the purpose of improving the acid generation efficiency of the photoacid generator and increasing the photosensitive wavelength. Any sensitizer may be used as long as the photoacid generator is sensitized by an electron transfer mechanism or an energy transfer mechanism. Preferably, aromatic polycondensed compounds such as anthracene, 9,10-dialkoxyanthracene, pyrene and perylene, aromatic ketone compounds such as acetophenone, benzophenone, thioxanthone and Michlerketone, heterocyclic compounds such as phenothiazine and N-aryloxazolidinone Is mentioned. The addition amount is appropriately selected according to the purpose, but is generally 0.01 to 1 mol%, preferably 0.1 to 0.5 mol%, based on the photoacid generator.

〔Antioxidant〕
An antioxidant can be added to improve the stability of the ink. Examples of the antioxidant include European Published Patent No. 223739, No. 309401, No. 309402, No. 310551, No. 310552, No. 4594416, German Published Patent No. 3435443. JP, 54-85535, 62-267047, 63-113536, 63-163351, JP-A-2-262654, JP-A-2-71262, Examples thereof include those described in Kaihei 3-121449, JP-A-5-61166, JP-A-5-119449, US Pat. No. 4,814,262, US Pat. No. 4,980,275, and the like.
The addition amount is appropriately selected according to the purpose, but is generally about 0.1 to 8% by mass in terms of solid content.

[Anti-fading agent]
Various organic and metal complex anti-fading agents can be used for the active energy curable ink. Examples of the organic anti-fading agent include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, and heterocycles. Examples of the metal complex anti-fading agent include nickel complexes and zinc complexes. No. 17643, VII, I to J, No. 15162, ibid. No. 18716, page 650, left column, ibid. No. 36544 at page 527, ibid. 307105, page 872, ibid. The compounds described in the patent cited in No. 15162 and the compounds included in the general formulas and compound examples of representative compounds described in JP-A-62-215272, pages 127 to 137 can be used. .
The addition amount is appropriately selected according to the purpose, but is generally about 0.1 to 8% by mass in terms of solid content.

[Conductive salts]
Conductive salts such as potassium thiocyanate, lithium nitrate, ammonium thiocyanate, and dimethylamine hydrochloride can be added to the active energy curable ink for the purpose of controlling ejection properties.

〔solvent〕
It is also effective to add an extremely small amount of an organic solvent to the active energy curable ink in order to improve the adhesion to the recording medium.
Examples of the solvent include ketone solvents such as acetone, methyl ethyl ketone, and diethyl ketone, alcohol solvents such as methanol, ethanol, 2-propanol, 1-propanol, 1-butanol, and tert-butanol, and chlorine such as chloroform and methylene chloride. Solvents, aromatic solvents such as benzene and toluene, ester solvents such as ethyl acetate, butyl acetate and isopropyl acetate, ether solvents such as diethyl ether, tetrahydrofuran and dioxane, glycols such as ethylene glycol monomethyl ether and ethylene glycol dimethyl ether And ether solvents.
In this case, it is effective to add the solvent within a range that does not cause the problem of solvent resistance and VOC, and the amount is preferably 0.1 to 5% by mass, more preferably 0.1 to 3% by mass with respect to the whole ink composition. % Range.

[Polymer compound]
Various polymer compounds can be added to the active energy curable ink in order to adjust film physical properties. High molecular compounds include acrylic polymers, polyvinyl butyral resins, polyurethane resins, polyamide resins, polyester resins, epoxy resins, phenol resins, polycarbonate resins, polyvinyl butyral resins, polyvinyl formal resins, shellacs, vinyl resins, acrylic resins. Rubber resins, waxes and other natural resins can be used. Two or more of these may be used in combination. Of these, vinyl copolymer obtained by copolymerization of acrylic monomers is preferred. Furthermore, a copolymer containing “carboxyl group-containing monomer”, “methacrylic acid alkyl ester”, or “acrylic acid alkyl ester” as a structural unit is also preferably used as the copolymer composition of the polymer binder.

[Surfactant]
A surfactant may be added to the active energy curable ink.
Examples of the surfactant include those described in JP-A Nos. 62-173463 and 62-183457. For example, anionic surfactants such as dialkylsulfosuccinates, alkylnaphthalenesulfonates, fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene / polyoxypropylene blocks Nonionic surfactants such as copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. An organic fluoro compound may be used in place of the surfactant. The organic fluoro compound is preferably hydrophobic. Examples of the organic fluoro compounds include fluorine surfactants, oily fluorine compounds (eg, fluorine oil) and solid fluorine compound resins (eg, tetrafluoroethylene resin). No. (columns 8 to 17) and those described in JP-A Nos. 62-135826.

In addition to this, for example, leveling additives, matting agents, waxes for adjusting film physical properties, polymerization to improve adhesion to a recording medium such as polyolefin or PET, and the like. It can contain a tackifier that does not obstruct.
As the tackifier, specifically, a high molecular weight adhesive polymer described in JP-A-2001-49200, 5-6p (for example, (meth) acrylic acid and an alkyl group having 1 to 20 carbon atoms). An ester with an alcohol having, an ester of (meth) acrylic acid with an alicyclic alcohol having 3 to 14 carbon atoms, a copolymer comprising an ester of (meth) acrylic acid with an aromatic alcohol having 6 to 14 carbon atoms) And a low molecular weight tackifying resin having a polymerizable unsaturated bond.

[Preferred physical properties of ink]
The active energy curable ink preferably has an ink viscosity of 20 mPa · s or less, more preferably 10 mPa · s or less at the temperature at the time of injection in consideration of ejection properties. It is preferable to adjust and determine the ratio.

  The common surface tension of the active energy curable ink is preferably 20 to 40 mN / m, more preferably 25 to 35 mN / m. When recording on various recording media such as polyolefin, PET, coated paper, and non-coated paper, 20 mN / m or more is preferable from the viewpoint of bleeding and penetration, and 40 mN / m or less is preferable from the viewpoint of wettability.

  In the printed matter obtained with the active energy curable ink, the image portion is cured by irradiation with active energy such as ultraviolet rays, and the strength of the image portion is excellent. It can be used for various purposes such as formation of a receiving layer (image portion).

[Radical polymerization ink composition]
The radical polymerization ink composition contains (d) a radical polymerizable compound, (e) a polymerization initiator, and (f) a colorant. If desired, it may further contain a sensitizing dye, a co-sensitizer and the like.
Hereinafter, each component used for the radical polymerization ink composition will be sequentially described.

(D) [Radically polymerizable compound]
Examples of the radically polymerizable compound include compounds having an ethylenically unsaturated bond capable of addition polymerization as described below.

[Compound having an ethylenically unsaturated bond capable of addition polymerization]
Examples of compounds having addition-polymerizable ethylenically unsaturated bonds that can be used in active energy curable inks include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc. ) And an aliphatic polyhydric alcohol compound, an amide of the unsaturated carboxylic acid and an aliphatic polyamine compound, and the like.

  Specific examples of the monomer of an ester of an aliphatic polyhydric alcohol compound and an unsaturated carboxylic acid include acrylic acid esters such as ethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butanediol diacrylate, and tetramethylene glycol. Diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane tri (acryloyloxypropyl) ether, trimethylolethane triacrylate, hexanediol diacrylate, 1,4-cyclohexanediol di Acrylate, Tetraethylene glycol diacrylate, Pentaerythritol diacrylate, Pentaerythritol triacrylate , Pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, tri (acryloyloxyethyl) isocyanurate, polyester acrylate oligomer.

  Methacrylic acid esters include tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, Hexanediol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol hexamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, bis [p- (3-methacryloxy 2-hydroxypro ) Phenyl] dimethyl methane, bis - [p- (acryloxyethoxy) phenyl] dimethylmethane. Itaconic acid esters include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate And sorbitol tetritaconate.

  Examples of crotonic acid esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, and sorbitol tetradicrotonate. Examples of isocrotonic acid esters include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, and sorbitol tetraisocrotonate. Examples of maleic acid esters include ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate. Furthermore, the mixture of the above-mentioned ester monomer can also be mention | raise | lifted. Specific examples of an amide monomer of an aliphatic polyvalent amine compound and an unsaturated carboxylic acid include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexa. Examples include methylene bis-methacrylamide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, and xylylene bismethacrylamide.

Other examples include vinyls containing a hydroxyl group represented by the following general formula (A) in a polyisocyanate compound having two or more isocyanate groups per molecule described in JP-B-48-41708. Examples thereof include a vinylurethane compound containing two or more polymerizable vinyl groups in one molecule to which a monomer is added. CH ₂ = C (R) COOCH ₂ CH (R ′) OH (A) (where R and R ′ represent H or CH ₃ ).
Further, as described in JP-A-51-37193, urethane acrylates, JP-A-48-64183, JP-B-49-43191, JP-B-52-30490, etc. Polyfunctional acrylates and methacrylates such as polyester acrylates and epoxy acrylates obtained by reacting an epoxy resin with (meth) acrylic acid can be used. Furthermore, Journal of Japan Adhesion Association vol.20, No. 7, pages 300 to 308 (1984) as photocurable monomers and oligomers can also be used. In the present invention, these monomers can be used in a chemical form such as a prepolymer, that is, a dimer, a trimer and an oligomer, or a mixture thereof and a copolymer thereof.

  The amount of the radical polymerizable compound used is usually 1 to 99.99%, preferably 5 to 90.0%, more preferably 10 to 70%, based on all components of the ink. (The% mentioned here is mass%.)

(E) [Photoinitiator]
Next, the photopolymerization initiator used for the radical polymerization ink composition will be described.
The photopolymerization initiator in the present invention is a compound that undergoes a chemical change through the action of light or interaction with the electronically excited state of a sensitizing dye to generate at least one of radicals, acids, and bases. It is.

  Preferred photopolymerization initiators include (a) aromatic ketones, (b) aromatic onium salt compounds, (c) organic peroxides, (d) hexaarylbiimidazole compounds, (e) ketoxime ester compounds, F) borate compounds, (to) azinium compounds, (thi) metallocene compounds, (li) active ester compounds, (nu) compounds having a carbon halogen bond, and the like.

(F) [Colorant]
The same (c) colorant as described in the cationic polymerization ink composition can be used.
In addition to the essential components described above, various additives can be used in combination with the active energy curable ink depending on the purpose. These optional components will be described.
[Sensitizing dye]
In the present invention, a sensitizing dye may be added for the purpose of improving the sensitivity of the photopolymerization initiator. Examples of preferred sensitizing dyes include those belonging to the following compounds and having an absorption wavelength in the 350 nm to 450 nm region.
Polynuclear aromatics (eg, pyrene, perylene, triphenylene), xanthenes (eg, fluorescein, eosin, erythrosine, rhodamine B, rose bengal), cyanines (eg, thiacarbocyanine, oxacarbocyanine), merocyanines ( For example, merocyanine, carbomerocyanine), thiazines (eg, thionine, methylene blue, toluidine blue), acridines (eg, acridine orange, chloroflavin, acriflavine), anthraquinones (eg, anthraquinone), squalium (eg, squalium) ), Coumarins (eg 7-diethylamino-4-methylcoumarin).

[Co-sensitizer]
Furthermore, a known compound having a function of further improving sensitivity or suppressing polymerization inhibition by oxygen may be added to the active energy curable ink as a co-sensitizer.

  Examples of such co-sensitizers include amines such as MR Sander et al., “Journal of Polymer Society”, Vol. 10, page 3173 (1972), Japanese Examined Patent Publication No. 44-20189, Japanese Patent Laid-Open No. 51-82102. Publication, JP 52-134692, JP 59-138205, JP 60-84305, JP 62-18537, JP 64-33104, Research Disclosure 33825 Specifically, triethanolamine, p-dimethylaminobenzoic acid ethyl ester, p-formyldimethylaniline, p-methylthiodimethylaniline and the like can be mentioned.

  Other examples include thiols and sulfides, for example, thiol compounds described in JP-A-53-702, JP-B-55-500806, JP-A-5-142772, and JP-A-56-75643. Examples thereof include disulfide compounds, and specific examples include 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 2-mercaptobenzimidazole, 2-mercapto-4 (3H) -quinazoline, β-mercaptonaphthalene and the like.

  Other examples include amino acid compounds (eg, N-phenylglycine), organometallic compounds described in Japanese Patent Publication No. 48-42965 (eg, tributyltin acetate), and hydrogen described in Japanese Patent Publication No. 55-34414. Donors, sulfur compounds described in JP-A-6-308727 (eg, trithiane), phosphorus compounds described in JP-A-6-250387 (diethylphosphite, etc.), Si-- described in Japanese Patent Application No. 6-191605 H, Ge-H compound, etc. are mentioned.

  Moreover, it is preferable to add 200-20000 ppm of a polymerization inhibitor from a viewpoint of improving storability. The active energy curable ink is preferably ejected by heating and reducing the viscosity in the range of 40 to 80 ° C., and a polymerization inhibitor is preferably added to prevent clogging of the head due to thermal polymerization. Examples of the polymerization inhibitor include hydroquinone, benzoquinone, p-methoxyphenol, TEMPO, TEMPOL, and cuperon Al.

[Others]
In addition, known compounds can be used as necessary. For example, surfactants, leveling additives, matting agents, polyester resins for adjusting film properties, polyurethane resins, vinyl resins, acrylic resins, etc. Resin, rubber resin, wax and the like can be appropriately selected and used. In order to improve the adhesion to a recording medium such as polyolefin or PET, it is also preferable to contain a tackifier that does not inhibit the polymerization. Specifically, high molecular weight adhesive polymers described in JP-A-2001-49200, 5-6p (for example, esters of (meth) acrylic acid and alcohols having an alkyl group having 1 to 20 carbon atoms) , An ester of (meth) acrylic acid and an alicyclic alcohol having 3 to 14 carbon atoms, a copolymer formed of an ester of (meth) acrylic acid and an aromatic alcohol having 6 to 14 carbon atoms), A low molecular weight tackifying resin having a saturated bond.

  It is also effective to add a trace amount of organic solvent in order to improve the adhesion to the recording medium. In this case, it is effective to add the solvent within a range that does not cause the problem of solvent resistance and VOC. % Range.

  In addition, as a means for preventing a decrease in sensitivity due to the light-shielding effect of the ink color material, it is also preferable to combine a cationic polymerizable monomer having a long polymerization initiator lifetime with a polymerization initiator to obtain a radical-cation hybrid type curable ink. One.

[Water-based ink composition]
The aqueous ink composition contains a water-soluble photopolymerization initiator that generates radicals by the action of a polymerizable compound and active energy. If desired, it may further contain a coloring material and the like.

[Polymerizable compound]
As the polymerizable compound contained in the aqueous ink composition, a polymerizable compound contained in a known aqueous ink composition can be used.
A reactive material can be added to the water-based ink composition in order to optimize the formulation considering end-user characteristics such as curing speed, adhesion, and flexibility. Examples of such reactive materials include (meth) acrylate (ie, acrylate and / or methacrylate) monomers and oligomers, epoxides, and oxetanes.
Examples of acrylate monomers include phenoxyethyl acrylate, octyl decyl acrylate, tetrahydrofuryl acrylate, isobornyl acrylate, hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, polyethylene glycol diacrylate (e.g., tetraethylene glycol). Diacrylate), dipropylene glycol diacrylate, tri (propylene glycol) triacrylate, neopentyl glycol diacrylate, bis (pentaerythritol) hexaacrylate, ethoxylated or propoxylated glycol and polyol acrylate (e.g. propoxylated neopentyl glycol Diacrylate, ethoxylated trimethylol proppant Acrylate), and mixtures thereof.
Examples of acrylate oligomers include ethoxylated polyethylene glycol, ethoxylated trimethylolpropane acrylate and polyether acrylate and ethoxylates thereof, and urethane acrylate oligomers.
Examples of methacrylates include hexanediol dimethacrylate, trimethylolpropane trimethacrylate, triethylene glycol dimethacrylate, diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, and mixtures thereof.
The addition amount of the oligomer is preferably 1 to 80% by weight and more preferably 1 to 10% by weight with respect to the total weight of the ink.

[Water-soluble photopolymerization initiator that generates radicals by the action of active energy]
The polymerization initiator that can be used for the active energy curable ink will be described. As an example, for example, a photopolymerization initiator having a wavelength of up to about 400 nm may be mentioned. As such a photopolymerization initiator, for example, a photopolymerization initiator represented by the following general formula (hereinafter referred to as TX) which is a substance having functionality in a long wavelength region, that is, a sensitivity to generate a radical upon receiving ultraviolet rays. In the present invention, it is particularly preferable to select and use them appropriately.

In the above general formulas TX-1 to TX-3, R2 represents — (CH ₂ ) _x — (x = 0 or 1), —O— (CH ₂ ) _y — (y = 1 or 2), substituted or unsubstituted Represents a phenylene group. When R2 is a phenylene group, at least one hydrogen atom in the benzene ring is, for example, a carboxyl group or a salt thereof, a sulfonic acid or a salt thereof, a linear or branched alkyl having 1 to 4 carbon atoms. May be substituted with one or more groups or atoms selected from a group, a halogen atom (fluorine, chlorine, bromine, etc.), an alkoxyl group having 1 to 4 carbon atoms, an aryloxy group such as a phenoxy group, and the like. . M represents a hydrogen atom or an alkali metal (for example, Li, Na, K, etc.). R3 and R4 each independently represents a hydrogen atom or a substituted or unsubstituted alkyl group. Examples of the alkyl group include, for example, a linear or branched alkyl group having about 1 to 10 carbon atoms, particularly about 1 to 3 carbon atoms. Moreover, as an example of the substituent of these alkyl groups, a halogen atom (a fluorine atom, a chlorine atom, an oxalic atom etc.), a hydroxyl group, an alkoxyl group (C1-C3 grade) etc. are mentioned, for example. M represents an integer of 1 to 10.

  Furthermore, in the present invention, a water-soluble derivative (hereinafter abbreviated as an IC system) of a photopolymerization initiator Irgacure 2959 (trade name: manufactured by Ciba Specialty Chemicals) having the following general formula may be used. Specifically, IC-1 to IC-3 having the following formulas can be used.

[Prescription for clear ink]
The above-mentioned water-soluble polymerizable compound can be made into a clear ink by making it into the form of a transparent water-based ink without containing the above-mentioned coloring material. In particular, if it is prepared so as to have ink jet recording characteristics, a clear ink for water-based photocurable ink jet recording can be obtained. If such an ink is used, a clear film can be obtained because it does not contain a color material. Clear inks that do not contain color materials can be used for undercoats to give recording materials suitable for image printing, or for surface protection of images formed with ordinary inks, further decoration and gloss The use etc. for the overcoat for the purpose of provision etc. are mentioned. In the clear ink, colorless pigments or fine particles that are not intended for coloring can be dispersed and contained according to these applications. By adding these, it is possible to improve various properties such as image quality, fastness, and workability (handling property) of the printed matter in both the undercoat and the overcoat.

  Prescription conditions for application to such a clear ink include 10 to 85% of a water-soluble polymerizable compound as a main component of the ink, a photopolymerization initiator (for example, an ultraviolet polymerization catalyst), and the above water-soluble polymerization. It is preferable to prepare such that 1 to 10 parts by mass with respect to 100 parts by mass of the active compound and at least 0.5 part of the photopolymerization initiator is simultaneously contained with respect to 100 parts of ink.

[Material composition of colorant-containing ink]
When the above-described water-soluble polymerizable compound is used in an ink containing a color material, the concentration of the polymerization initiator and the polymerizable substance in the ink can be adjusted in accordance with the absorption characteristics of the contained color material. preferable. As described above, the amount of water or solvent is in the range of 40% to 90%, preferably 60% to 75%, based on mass, as the blending amount. Furthermore, the content of the polymerizable compound in the ink is in the range of 1% to 30%, preferably in the range of 5% to 20% on the mass basis with respect to the total amount of the ink. Although the polymerization initiator depends on the content of the polymerizable compound, it is generally in the range of 0.1 to 7%, preferably 0.3 to 5% on the mass basis with respect to the total amount of the ink.

  When a pigment is used as the ink coloring material, the concentration of the pure pigment in the ink is generally in the range of 0.3% by mass to 10% by mass with respect to the total amount of the ink. The coloring power of the pigment depends on the dispersion state of the pigment particles, but if it is in the range of about 0.3 to 1%, it becomes a range used as a light-colored ink. On the other hand, if it is more than that, it gives a density used for general color coloring.

  As described above, the droplet ejection point size detection method according to the present invention has been described in detail. However, the present invention is not limited to the above embodiment, and various improvements and modifications can be made without departing from the gist of the present invention. May be performed.

It is a front view which shows schematic structure of an example of the digital label printing apparatus which can use the droplet ejection point deviation detection method of this invention. It is a longitudinal cross-sectional view which shows the layer structure of a recording medium. It is a schematic perspective view which expands and shows the drawing part of the digital label printing apparatus shown in FIG. (A) is a front view showing an arrangement pattern of ejection portions of the recording head, and (B) is an enlarged sectional view showing one ejection portion of the recording head shown in (A). It is a schematic diagram which shows the structure of the ink supply system and head peripheral part in an inkjet drawing apparatus. The foil pressing state is shown, (A) is a cross-sectional view of the main part of the recording medium having a large unevenness on the image surface, (B) is a cross-sectional view of the main part of the recording medium pressed without smoothing, (C) is It is principal part sectional drawing of the recording medium which smoothed the unevenness | corrugation by the smoothing means, and was foil-pressed. (A) is a side view showing the relationship between each ejection part of the recording head and the landing position of the ink droplet, and (B) is a top view of (A). FIG. 6 is a top view showing an example of a droplet ejection point position detection image and a droplet ejection point size detection image. (A) is a schematic diagram illustrating an example of one droplet ejection point portion of an image read by the droplet ejection point detection unit, and (B) is an example in which the image data illustrated in (A) is binarized. It is a schematic diagram shown. (A) And (B) is a schematic diagram explaining an example of the calculation method of the position of the both ends of a droplet ejection point, respectively. It is an enlarged top view which expands and shows a part of row | line | column of a droplet ejection point. It is a schematic diagram which shows the approximate straight line computed for every discharge part. (A) is a graph showing an example of the relationship between each position in the X-axis direction and the image density, and (B) is a graph showing an example of the relationship between the image density and the droplet ejection point size. It is a front view which shows an example of the relationship between a discharge part and the droplet ejection point formed on a to-be-recorded medium. FIG. 5 is an explanatory diagram schematically showing the relationship between each ejection unit, the size of the droplet ejection point, and the image density when the droplet ejection point size is detected without being based on the droplet ejection point position. It is explanatory drawing which shows typically the relationship between each discharge part, the size of a droplet ejection point, and image density at the time of detecting a droplet ejection point size based on a droplet ejection point position. FIG. 10 is a top view illustrating another example of the arrangement pattern of the ejection units of the recording head. It is a schematic block diagram which shows another example of the apparatus structure which can use the droplet ejection point shift | offset | difference detection method of this invention. (A) is a schematic top view showing an example of a droplet ejection point position detection image and a droplet ejection point size detection image used in this example, and (B) shows (A) in more detail. FIG. (A) is a graph showing the calculated droplet ejection point size, and (B) is a graph showing the calculated droplet ejection point interval. It is a schematic block diagram of the digital label printing apparatus of the modification of the digital label printing apparatus shown in FIG. It is a front view which shows schematic structure of an inkjet drawing apparatus. It is a top view which shows the adsorption | suction conveyance bell and recording head unit of the inkjet drawing apparatus shown in FIG. It is a principal part block diagram which shows the system configuration | structure of the control part shown in FIG.

Explanation of symbols

60 Discharge Unit 61 Ink Chamber Unit 62 Nozzle 63 Pressure Chamber 64 Supply Port 65 Common Channel 66 Actuator 67 Pressure Plate 68 Individual Electrode 70 Ink Supply Tank 72 Filter 74 Cap 76 Cleaning Blade 77 Suction Pump 78 Collection Tank 80 Communication Interface 82 System Controller 84 Image memory 86 Motor driver 88 Heat driver 90 Print control unit 92 Image buffer memory 94 Head driver 96 Host computer 98 Motor 99 Heater 100 Digital label printing device 110, 714 Conveying unit 112, 716 Drawing unit 114, 724 Dropping point detection unit 116 Smoothing unit 118 Foil pressing unit 120 Label removing unit 121, 722 Control unit 122 Supply roll 124, 126, 128, 130, 132 Conveying roller pair 134 Product winding unit 135, 750 Recording head unit 136C, 136M, 136Y, 136K, 750K, 750C, 750M, 750Y Recording head (inkjet head)
137, 752 Ink storage / loading unit 138 UV irradiation unit 142 Varnish coater 144, 145 Coating roller 146 Flat pressure member 148 UV irradiation unit 150 Foil supply roll 152 Foil winding rolls 154, 156, 737b Roller 158 Foil 160 Hot stamp Plate 162 Varnish coater 164 Ultraviolet irradiation unit 166 Die cutter 168 Cylinder cutter 170 Receiving roller 172 Waste removal unit 710 Inkjet drawing device 712 Supply unit 718 Heating / pressurizing unit 720 Discharge unit 730 Magazine 732 Heating drum 734, 756b Fixed blade 734a, 756a 734 , 756b Round blade 736 Suction belt transport unit 738 Belt 739 Suction chamber 740 Fan 742 Belt cleaning unit 744 Heating fan 746 Rear drying unit 7 4 the pressure roller 758 discharge portion P of the recording medium

Claims (10)

Droplet point size detection that detects the size of the ink droplets that are ejected from each ejection part of a recording head in which a plurality of ejection parts that eject ink droplets are arranged in a line and land on the recording medium A method,
A first image forming step of ejecting ink droplets from the ejection section to form a first image in which droplet ejection points are formed on the recording medium;
A second image forming step of forming a second image in which ink droplets are ejected from the ejection unit and droplet ejection points are formed on the recording medium;
A droplet ejection point position detecting step of reading the first image and detecting a droplet ejection point position formed by each of the ejection units from the read first image;
A droplet ejection point size detecting step for reading the second image and detecting a droplet ejection point size of each ejection unit based on the read image density information of the second image and the droplet ejection point position;
A method for detecting a droplet ejection size, comprising:   2. The droplet ejection point size detection method according to claim 1, wherein the second image forming step forms a second image having an image area ratio of 40% to 60%.   3. The droplet ejection point size detection method according to claim 1, wherein the second image forming step forms the second image on the same recording medium as the recording medium on which the first image is formed.   4. The method according to claim 1, wherein in the first image forming step, the droplet ejection point is formed in a size that does not contact a droplet ejection point adjacent in a width direction of the recording medium and a direction orthogonal to the width direction. 2. A method for detecting the size of a droplet ejection point according to crab.   5. The first image forming step forms the droplet ejection point at a position that is not in contact with the droplet ejection point adjacent in the width direction of the recording medium and in a direction orthogonal to the width direction. 2. A method for detecting the size of a droplet ejection point according to crab. In the first image forming step, a plurality of ink droplets are ejected from the ejection unit, and a plurality of droplet ejection points are formed for each ejection unit,
The droplet ejection point position detecting step includes:
An image reading step of reading the first image as a read image with a direction orthogonal to a direction substantially parallel to a direction in which a plurality of droplet ejection points formed by one of the ejection units being arranged as a reference direction;
The droplet ejection point position for calculating one droplet position and the other edge position in the reference direction of each droplet ejection point of each of the scanned images as the droplet ejection point position information by performing image processing on the scanned image. An information calculation step;
A droplet ejection point position information classification step for classifying the droplet ejection point position information as droplet ejection point position classification information for each ejection unit that ejected each droplet ejection point;
Based on the droplet ejection point position classification information, an approximate straight line that connects one end position of a plurality of droplet ejection points discharged from one discharge unit and an approximate straight line that connects the other end position respectively. An approximate straight line calculation step for calculating the slope of the approximate straight line in common for each discharge unit;
2. A droplet ejection point position calculating step of calculating a droplet ejection point position of the ejection unit from the approximate straight line of one end position calculated for each ejection unit and the approximate straight line of the other end position. The method for detecting a droplet ejection size according to any one of -5. The droplet ejection point position detecting step includes:
Further, the interval between the droplet ejection point of the ejection unit and the droplet ejection point of the other ejection unit is calculated from the approximate straight line of one end position calculated for each ejection unit and the approximate straight line of the other end position. The droplet ejection point size detection method according to claim 6, further comprising a droplet ejection point interval calculation step.   The method of detecting a droplet ejection point size according to claim 6 or 7, wherein the approximate straight line is calculated by a least square method.   The first image forming step forms a row of droplet ejection points to be formed on the recording medium at different positions in a direction orthogonal to the arrangement direction of the ejection units according to the arrangement position of the ejection units. The droplet ejection point size detection method according to any one of 6 to 8.   In the first image forming step, after the ink droplets are ejected from every other ejection section of the plurality of ejection sections to form the row of droplet ejection points on the recording medium, the remaining of the remaining droplets 10. The droplet ejection point size detection method according to claim 9, wherein ink droplets are ejected from the ejection unit to form a row of droplet ejection points on the recording medium in the previous period.

Images