JP2021091124A - Head height tilt detection method in ink jet printer - Google Patents

Abstract

To make it possible to detect a tilt of a head in a height direction only by printing a line segment by changing speed.SOLUTION: When a head of printing head has a tilt in a height direction, a gap between the head and continuous paper gradually becomes larger from one to the other in a width direction Y. Therefore, when conveying speed is increased, the larger the interval between the head and the continuous paper is, the more largely the tilts of line segments DL1, DL2 to be detected are printed. Thus, when tilts of the line segments DL1, DL2 to be detected in a width direction are larger than tilts of line segments DL1, DL2 to be detected printed at conveying speed slower than the same, it is shown that the head has a tilt in the height direction. As a result, simply by changing the conveying speed and printing a test chart, it is possible to detect whether or not the head has a tilt in the height direction.SELECTED DRAWING: Figure 13

Description

The present invention relates to a method for detecting the height inclination of a head in an inkjet printing apparatus that prints on a print medium by relatively moving a print head provided with a head for ejecting ink droplets and a print medium.

Conventionally, as this type of method, while transporting printing paper to a printing head having a plurality of heads, ink droplets are ejected from each head to print a head position adjusting chart, and the head position adjusting chart is used. There is one that adjusts the position of the head in the print head based on the above (see, for example, Patent Document 1).

In this method, after printing the head position adjustment chart, the position deviation and inclination of each head on a plane parallel to the printing paper in the print head are detected according to the inclination of the line segment for each head.

Japanese Unexamined Patent Publication No. 2013-159040 (Fig. 9)

However, in the case of the conventional example having such a configuration, there are the following problems.
That is, although the conventional method can detect the positional deviation and inclination of each head on a plane parallel to the printing paper, the inclination of each head in the printing head in the height direction (direction perpendicular to the plane parallel to the printing paper). Cannot be detected.

Since the inkjet printing apparatus ejects ink droplets while conveying the printing paper to the printing head, if the head is tilted in the height direction, the printing paper is conveyed as the conveying speed of the printing paper is increased. The degree to which the straight line printed in the width direction of is inclined in the transport direction becomes large. Generally, in order to improve the printing throughput, the transfer speed is increased. Therefore, it is necessary to detect the inclination of the head in the height direction, which causes the print quality to deteriorate as the transfer speed is increased. Is important.

The present invention has been made in view of such circumstances, and the height inclination detection of the head in an inkjet printing apparatus capable of detecting the inclination in the height direction of the head only by printing a line segment at a different speed. The purpose is to provide a method.

The present invention has the following configuration in order to achieve such an object.
That is, the invention according to claim 1 is a printing head in a method for detecting height inclination of a head in an inkjet printing apparatus that prints while relatively moving a printing head provided with a head for ejecting ink droplets and a printing medium. And the printing medium are relatively moved at the first speed, and the first line segment is printed in a direction orthogonal to the relative movement direction, and at a second speed faster than the first speed. A step of printing a second line segment in a direction orthogonal to the relative movement direction in a state where the print head and the print medium are relatively moved, and the second line in a direction orthogonal to the relative movement direction. When the inclination of the minute is larger than the inclination of the first line segment, it is characterized by including a step of determining that the head has an inclination in the height direction.

[Action / Effect] According to the invention of claim 1, when the head of the print head has an inclination in the height direction, the distance between the head and the print medium is one side in the direction orthogonal to the relative movement direction. It gradually grows toward the other. Therefore, when the relative moving speed is increased, the larger the distance between the head and the printing medium, the larger the inclination of the second line segment is printed. Therefore, when the inclination of the second line segment in the direction orthogonal to the relative moving direction is larger than the inclination of the first line segment, it means that the head has an inclination in the height direction. As a result, it is possible to detect whether or not there is an inclination in the height direction of the head simply by printing the line segment at different speeds.

Further, in the present invention, after the step of printing the first line segment and before the step of printing the second line segment, the inclination of the first line segment in a direction orthogonal to the relative moving direction. The step of determining whether or not the head has a slope equal to or higher than the first threshold, and when the slope of the first line segment has a slope equal to or higher than the first threshold, the tilt of the head in the relative moving direction. It is preferable to carry out the step of adjusting so as to eliminate the above (claim 2).

When the head is attached to the print head in a state of being tilted in the relative movement direction on a plane including the relative movement direction and the direction orthogonal to the relative movement direction instead of the height direction, the first method is used. The line segment and the second line segment are printed so as to be tilted in the relative movement direction with respect to the direction orthogonal to the relative movement direction on the plane. This slope does not change even if the speed is changed, but since it is included in the slopes of the first line segment and the second line segment, it is difficult to compare them. Therefore, after printing the first line segment, if the inclination of the first line segment is equal to or greater than the first threshold value, the head is adjusted so as to eliminate the inclination in the direction orthogonal to the relative movement direction. Then print the second line segment. Therefore, since the inclination with respect to the direction orthogonal to the relative movement direction can be eliminated, the inclination of the second line segment can be easily and accurately compared.

Further, in the present invention, before the step of printing the first line segment by using a head different from the head and attached to the print head in a state where there is no inclination in the height direction as a reference head. And, before the step of printing the second line segment, a step of printing the reference line segment on the printing medium in the direction orthogonal to the relative moving direction by the reference head is carried out, and the first line segment is printed. And the second line segment is preferably printed in the vicinity of the reference line segment, respectively (claim 3).

Since the reference head prints a reference line segment that has no inclination in the direction orthogonal to the relative movement direction, when the first line segment and the second line segment are printed close to this reference line segment, the respective inclinations are printed. Easy to detect.

Further, in the present invention, it is preferable that the reference line segment is printed only by a plurality of nozzles located on both ends in a direction orthogonal to the relative moving direction among the plurality of nozzles included in the reference head. (Claim 4).

The reference line segment is printed only at the positions corresponding to both ends of the head in the direction orthogonal to the relative movement direction. While it is possible to compare the inclinations of the first line segment and the second line segment with respect to the reference line segment, it is possible to suppress the consumption of ink when detecting the inclination of the head.

Further, in the present invention, the reference line segment is a first reference line segment group in which two lines are printed with a first interval in the relative movement direction, and a second interval wider than the first interval. The first line segment and the second line segment are printed at the first interval and the second interval, and the first line segment and the second line segment are printed at the first interval and the second interval. The second interval is an interval in which the positional relationship between the first line segment and the second line segment and the first reference line segment group can be visually recognized, and the first interval is the interval in which the first line segment can be visually recognized. It is preferable that the positional relationship between the minute and the second line segment and the second reference line segment group is a distance that can be visually recognized by the expanding means (claim 5).

When there are a plurality of heads constituting the print head, it is necessary to detect the inclination in the height direction for each head. Since it is possible to visually know whether or not the second reference line segment has an inclination in the height direction, it is possible to roughly determine which head has the inclination in the height direction. Therefore, since it is only necessary to confirm the first reference line segment group by the enlarging means only for the heads that have a guess, it is possible to efficiently detect the inclination in the height direction when the print head is composed of a plurality of heads. ..

Further, in the present invention, it is preferable that the print medium has a ruled line in a direction orthogonal to the relative movement direction (claim 6).

If the print medium has a ruled line, the inclination of the first line segment and the second line segment can be easily detected with the ruled line as a reference. Therefore, it is not necessary to print an extra line segment, and ink consumption can be suppressed.

According to the method for detecting the height inclination of the head in the inkjet printing apparatus according to the present invention, when the head of the printing head has an inclination in the height direction, the distance between the head and the printing medium in a direction orthogonal to the relative moving direction. Gradually increases from one side to the other. Therefore, when the relative moving speed is increased, the larger the distance between the head and the printing medium, the larger the inclination of the second line segment is printed. Therefore, when the inclination of the second line segment in the direction orthogonal to the relative moving direction is larger than the inclination of the first line segment, it means that the head has an inclination in the height direction. As a result, it is possible to detect whether or not there is an inclination in the height direction of the head simply by printing the line segment at different speeds.

It is a schematic block diagram which shows the whole of the inkjet printing system which concerns on Example. Top view showing a schematic schematic configuration of a printing unit It is a perspective view of the print head which shows the state which only one head module is attached to the base plate. It is a perspective view which looked at the head module alone from above. It is a perspective view which looked at the head module alone from the bottom. It is a perspective view provided for explaining the positional relationship between a head and continuous paper. (A) is a diagram showing a print result when the head is not tilted with respect to the Y axis, and (b) is a diagram showing a print result when the head is tilted with respect to the Y axis. It is a figure explaining the case where the head is tilted with respect to the Z axis. The printing result in the case where the head is tilted with respect to the height direction Z is shown, (a) shows the case where the continuous paper is conveyed at a low speed, and (b) shows the case where the continuous paper is conveyed at a high speed. It is a table which shows the result of having calculated the deviation amount of a line segment in the case where the head is tilted in the height direction Z for each transport speed and tilt amount. It is a figure which provides the explanation of the adjustment amount which should adjust the inclination of the head in the height direction Z. It is a figure which shows an example of a test chart. It is a figure which shows an example of the inclination detection chart in the height direction Z. It is a flowchart which shows the inclination detection adjustment processing in the height direction. It is a figure which shows the modification 1 of the detection chart. It is a figure which shows the modification 2 of the detection chart.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing the entire inkjet printing system according to the embodiment.

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

The inkjet printing device 3 prints on a long continuous paper WP. The paper feed unit 5 holds the roll of the continuous paper WP rotatably around the horizontal axis, unwinds the continuous paper WP from the roll of the continuous paper WP in the transport direction X, and supplies the continuous paper WP to the inkjet printing apparatus 3. The paper ejection unit 7 winds up the continuous paper WP printed by the inkjet printing device 3 around the horizontal axis. Assuming that the supply side of the continuous paper WP is upstream and the discharge side of the continuous paper WP is downstream, the paper feed unit 5 is arranged on the upstream side of the inkjet printing device 3, and the paper discharge unit 7 is located on the downstream side of the inkjet printing device 3. Is located in.

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

The inkjet printing apparatus 3 includes a first drive roller M1 for taking in the continuous paper WP from the paper feeding unit 5 on the upstream side. The continuous paper WP unwound from the paper feed unit 5 by the first drive roller M1 is conveyed toward the paper discharge unit 7 arranged on the downstream side of the transfer direction X along the rotatable transfer roller 11 and the like. Will be done.

An edge position control unit 15 is arranged on the downstream side of the first drive roller M1. The edge position control unit 15 automatically adjusts when the continuous paper WP meanders in the direction orthogonal to the conveying direction X, and controls so that the continuous paper WP is conveyed to the correct position.

A second drive roller M2 is arranged on the downstream side of the edge position control unit 15. The continuous paper WP sent to the downstream side by the second drive roller M2 is delivered by the transfer roller 11 arranged on the downstream side of the second drive roller M2 in the printing area for printing along the transfer path. The transport direction can be changed. A rotary encoder (not shown) is attached to the transfer roller 11. A print unit 19 is arranged above the print area. The printing unit 19 is composed of, for example, four inkjet printing heads 21 to 24. For example, the most upstream print head 21 ejects black (K) ink droplets, the next print head 22 ejects cyan (C) ink droplets, and the next print head 23 ejects magenta (M). Ink droplets are ejected, and the next print head 24 ejects yellow (Y) ink droplets. Each of the print heads 21 to 24 is attached to a print head holding portion (not shown) of the print unit 19 so as to be arranged at a predetermined interval in the transport direction X.

The direction of the continuous paper WP printed in the printing area is changed by the transport roller 11 on the downstream side. A third drive roller M3 is arranged at that position. The third drive roller M3 winds the continuous paper WP at a large winding angle and abuts on the continuous paper WP to dry the ink droplets of the continuous paper WP. The third drive roller M3 has a built-in heater and is also called a heat drum.

The continuous paper WP dried by the third drive roller M3 is sent to the paper ejection unit 7 by the fourth drive roller M4 while being changed in direction by the plurality of transfer rollers 11. An inspection unit 27 is arranged on the upstream side of the fourth drive roller M4. The inspection unit 27 inspects the continuous paper WP printed by the printing unit 19. The paper ejection unit 7 winds up the continuous paper WP inspected by the inspection unit 27 in a roll shape.

The nip roller 29 is rotatably attached to the first drive roller M1, the second drive roller M2, and the fourth drive roller M4 described above. The conveying force to the continuous paper WP is imparted by sandwiching the continuous paper WP between the nip rollers 29 and the driving rollers. The pressing force by the nip roller 29 is applied by, for example, an air cylinder (not shown). The nip roller 29 is made of an elastic body such as rubber.

The inkjet printing apparatus 3, the paper feeding unit 5, and the paper discharging unit 7 described above are collectively controlled by the main control unit 31. The main control unit 31 is connected to an operation unit 33 that is operated to print test charts, which will be described later, and to instruct printing conditions including the transport speed of continuous paper WP and tension during printing.

Here, reference is made to FIG. Note that FIG. 2 is a plan view showing a schematic schematic configuration of the printing unit 19.

In the printing unit 19, the printing heads 21 to 24 are arranged in this order from upstream to downstream. Each of the print heads 21 to 24 has a plurality of heads 35 arranged in a row on the base plate 25 in a row toward the width direction Y of the continuous paper WP orthogonal to the transport direction X. Further, at a position separated from a plurality of heads 35 arranged in a row by a predetermined distance in the transport direction X, one head 35 is located between the heads 35 when the heads 35 are viewed from the transport direction X. Are arranged, and a plurality of heads 35 are arranged so that they are arranged in a row in the width direction Y. In other words, the print heads 21 to 24 are each composed of a plurality of heads 35 arranged in a so-called staggered pattern. Each head 35 is a lower surface facing the upper surface of the continuous paper WP, and includes a plurality of nozzles 37 for ejecting ink droplets along the width direction X.

Here, the structure of the print heads 21 to 24 will be described with reference to FIGS. 3 to 5. Since the print heads 21 to 24 have the same structure, the print head 21 for ejecting black (K) ink droplets will be described in detail here as an example. Note that FIG. 3 is a perspective view of the print head 21 showing a state in which only one head module 41 is attached to the base plate 25, and FIG. 4 is a perspective view of the head module 41 alone as viewed from above. FIG. Is a perspective view of the head module 41 alone as viewed from below.

The print head 21 includes a base plate 25 to which a plurality of head modules 41 can be attached, and a plurality of head modules 41. A total of 12 head modules 41 can be attached to the base plate 25 for 4 columns in the Y direction and 3 rows for X. The print head 21 is fixed to the print unit 19 by fixing the base plate 25 to which the 12 head modules 41 are attached to the print head holding portion of the print unit 19. A state in which only one head module 41 is mounted on the base plate 25 in FIG. 3 is shown.

One head module 41 includes one module base plate 43 and four heads 35. Four insertion ports 45 are formed in one module base plate 43. One head 35 is inserted into each insertion port 45. Each head 35 is attached to the module base plate 43 so that its position can be finely adjusted by an adjusting pin 47 that adjusts its position in the transport direction X and the width direction Y. Further, each head 35 is fixed to the module base plate 43 by a fixing pin 49 at a position in the transport direction X and the width direction Y adjusted by the adjusting pin 47. The position adjustment in the height direction Z is performed, for example, by sandwiching a thin steel plate between the module base plate 43 and the head 35 as a thin plate-shaped member (also referred to as a shim).

Each head module 41 configured as described above is inserted into the module insertion port 51 formed in the base plate 25. Each head module 41 inserted into the module insertion port 51 is fixed in position with respect to the base plate 25 by a locking pin 53 erected on the base plate 25.

Next, with reference to FIGS. 6 and 7, the positional relationship between the head 35 of the print heads 21 to 24 and the continuous paper WP and the change in linear printing due to the positional relationship will be described. Note that FIG. 6 is a perspective view for explaining the positional relationship between the head 35 and the continuous paper WP, and FIG. 7A shows a printing result when the head 35 is not tilted with respect to the Y axis. FIG. 7B is a diagram showing a printing result when the head 35 has an inclination with respect to the Y axis.

A line segment L1 extending in the width direction Y is printed in a state where the head 35 is not displaced in the width direction Y on the XY plane. In this case, as shown in FIG. 7A, the line segment L is printed parallel to the width direction Y.

On the other hand, the line segment L extending in the width direction Y is printed in a state where the head 35 has an inclination of an angle θ in the width direction Y on the XY plane. In this case, as shown in FIG. 7B, a line segment L inclined in the width direction Y is printed on the XY plane. In this case, even if the printing conditions are changed to change the transport speed of the continuous paper WP, if the angle θ, which is the deviation of the head 35 with respect to the width direction Y, does not change, the inclination of the line segment L also remains unchanged at the angle θ. Is.

When the head 35 has an inclination in the width direction Y, the inclination of the line segment L with respect to the width direction Y is obtained regardless of the printing conditions, and the inclination of the head 35 in the width direction Y is adjusted according to the inclination. Then, it can be corrected so that the inclination of the line segment L in the width direction Y disappears.

Next, reference is made to FIGS. 8 and 9. Note that FIG. 8 is a diagram illustrating a case where the head is tilted with respect to the Z axis, and FIG. 9 shows a printing result when the head is tilted with respect to the height direction Z. FIG. Is a case where the continuous paper WP is conveyed at a low speed, and (b) shows a case where the continuous paper WP is conveyed at a high speed.

Here, when the head 35 is not tilted in the height direction Z in the YZ plane (is orthogonal to the Z axis and is tilted in the height direction Z with respect to the width direction Y), which is shown by a solid line in FIG. In contrast to the case where the head 35 is tilted in the height direction Z in the YZ plane (when it is not orthogonal to the Z axis and is not orthogonal to the Z axis) as shown by the two-point chain line in FIG. (When tilted in the height direction Z) will be described. The distance between the lower surface of the head 35 (ink ejection surface) and the upper surface of the continuous paper WP is set to Dp [mm], and the distance at the end of the head 35 in the height direction Z is set to the amount of inclination M and [μm]. ..

In a state where the head 35 is inclined with respect to the height direction Z, the line segment L extending in the width direction Y is printed while the continuous paper WP is conveyed at a low transfer speed Vf. Then, as shown in FIG. 9A, a line segment L substantially parallel to the transport direction Y is printed. Strictly speaking, it is inclined with respect to the transport direction Y, but since it does not pose a problem in print quality here, it is assumed that it is substantially parallel to the transport direction Y.

On the other hand, the line segment L extending in the width direction Y is printed while the continuous paper WP is conveyed at a high transfer speed. Then, as shown in FIG. 9B, the line segment L is not parallel to the transport direction Y but has a deviation amount Lg. This is a phenomenon that occurs because the head 35 is an inkjet type. That is, the head 35 is tilted in the height direction Z, and the interval Dp is different at both ends of the head 35. On the other hand, since the velocity of the ink droplets ejected from each nozzle 37 (droplet velocity Vd [mps]) is constant, there is a difference in the time until the ink droplets land on the continuous paper WP at both ends of the head 35. Specifically, the nozzle 37 located at the head end having a wider interval Dp has a longer time for ink droplets to land on the continuous paper WP than the nozzle 37 located at the head end having a narrower interval Dp. become longer. As a result, the line segment L is no longer parallel to the transport direction Y, and the line segment L, which does not pose a problem in print quality at low speeds, has a large effect at high speeds and is printed inclined in the transport direction Y. .. That is, the print quality deteriorates when printing at high speed.

As shown by the alternate long and short dash line in FIG. 8, the deviation amount Lg [μm] of the line segment L when the head 35 is tilted in the height direction Z can be calculated by the following equation (1).

Deviation amount Lg = (tilt amount M / droplet velocity Vd) × transport speed Vf × 1000 …… (1)

Here, reference is made to FIG. Note that FIG. 10 is a table showing the results of calculating the deviation amount of the line segment L when the head is tilted in the height direction Z for each of the transport speed and the tilt amount.

As described above, even if the inclination amount M is constant, it can be seen that the deviation amount Lg increases as the transport speed Vf increases. Further, it can be seen that even if the transport speed Vf is constant, the deviation amount Lg increases as the inclination amount M increases.

Here, reference is made to FIG. Note that FIG. 11 is a diagram provided for explaining an adjustment amount for adjusting the inclination of the head in the height direction Z.

As described above, when the head 35 is tilted in the height direction Z, the line segment L is printed under predetermined printing conditions, and then the deviation amount Lg is obtained and the head 35 is tilted according to the tilt of the line segment L. The inclination of is adjusted. Since the adjustment amount is the inclination amount M, it can be obtained from the above equation (1) as shown in the following equation (2).

Inclination amount M = (deviation amount Lg × droplet velocity Vd) / (conveyance velocity Vf × 1000) …… (2)

However, as shown in FIG. 11, the inclination amount M is a value at the end portions of the plurality of nozzles 37. In reality, the head 35 does not have nozzles 37 formed at both ends. Therefore, if the inclination amount M is adjusted, the adjustment will be insufficient. Therefore, assuming that the length in the width direction Y in which the plurality of nozzles 37 are formed is D1 and the length in the width direction Y of the head 35 is D2, the inclination amount M1 to be adjusted is expressed as follows. ..

Amount of inclination to be adjusted M1 = M × (D2 / D1) …… (3)

Therefore, after printing the line segment L, the inclination amount M of the line segment L with respect to the width direction Y is measured, and the inclination amount M1 to be adjusted is calculated from the inclination amount M. Then, the inclination of the head 35 with respect to the module base plate 43 is adjusted by the inclination amount M1 to be adjusted. Thereby, the inclination of the head 35 with respect to the height direction Z can be corrected.

Next, reference is made to FIGS. 12 and 13. Note that FIG. 12 is a diagram showing an example of a test chart, and FIG. 13 is a diagram showing an example of an inclination detection chart in the height direction Z.

The main control unit 31 operates each unit to print the test chart TC as shown in FIG. 12 on the continuous paper WP. Note that FIG. 12 is an example in which the test chart TC is printed using only three heads 35 in order to facilitate understanding of the explanation. The test chart TC in this embodiment includes, for example, a patch PT, a first detection chart DT1, and a second detection chart DT2.

For example, the patch PT prints a predetermined length in the transport direction X while ejecting ink droplets from all the nozzles 37 of the head 35, and prints a rectangular area at a substantially constant density. At this time, it is preferable to eject as many ink droplets as possible so as to clear the clogging of the nozzle 37. After printing this patch PT, the first detection chart DT1 and the second detection chart DT2 are printed, so that the first detection chart DT1 and the second detection chart DT2 are eliminated from the influence of clogging. Can be printed with high quality. Therefore, the inclination can be detected with high accuracy.

The first detection chart DT1 is composed of two first reference line segment groups RLG1 and one detection target line segment DL1.

The first reference line segment group RLG1 is printed by the head 35 which is not tilted with respect to the transport direction X and the height direction Z. It is unknown whether or not the detection target line segment DL1 is tilted with respect to the transport direction X and the height direction Z, and is printed by the head 35 which is the target of tilt detection. Specifically, the first reference line segment group RLG1 prints the first reference line segment RL1 by a plurality of nozzles 37 on both end sides excluding the nozzle 37 at the center of the head 35, and the first reference line segment RL1 is printed in the transport direction X. The first reference line segment RL1 is printed in the same manner at positions separated by the interval W1 of 1. Further, a detection target line segment DL1 having substantially the same length in the width direction Y as the first reference line segment L1 is printed between the first reference line segments L1. Specifically, the first interval W1 is, for example, 6 lines in terms of the number of rows in the transport direction X of the nozzle 37.

The second detection chart DT2 is composed of two second reference lines RL2 and one detection target line segment DL2.

The second reference line segment RL2 is printed by the head 35 which is not tilted with respect to the transport direction X and the height direction Z. It is unknown whether or not the detection target line segment DL2 is tilted with respect to the transport direction X and the height direction Z, and is printed by the head 35 which is the target of tilt detection. The second reference line RL2 is printed in the same manner as the first reference line RL1 described above. That is, the second reference line segment RL2 is printed by the plurality of nozzles 37 on both end sides excluding the nozzles 37 in the center of the head 35, and the same is performed at a position separated by the second interval W2 in the transport direction X. The second reference line segment RL2 is printed. However, the second interval W2 is set wider than the above-mentioned predetermined distance W1. Specifically, the second interval W2 is, for example, 9 lines in terms of the number of rows in the transport direction X of the nozzle 37.

The second interval W2 described above is an interval at which an operator of the inkjet printing system 1 can visually distinguish between the second reference line segment group RLG2 and the second reference line RL2 without using an enlarging means such as a loupe. On the other hand, the first interval W1 is an interval at which the first reference line segment group RLG1 and the first reference line RL1 can be visually distinguished by using an expanding means such as a loupe. What can be identified here is whether or not the detection target line segment DL1 is inclined with respect to the first reference line segment group RLG1, and the detection target line segment DL2 is inclined with respect to the second reference line segment group RLG2. It means whether or not it can be judged.

The main control unit 31 prints the test chart TC having the above-described configuration at two different transport speeds. The two types of transport speeds are a transport speed Vf1 and a transport speed Vf2, and the transport speed Vf2 is set to be faster than the transport speed Vf1. For example, the transport speed Vf1 = 120 [mpm] and the transport speed Vf2 = 180 [mpm]. The same test chart is printed at each transfer speed, and the inclination of the head 35 is detected and corrected.

The first reference line DL1 and the second reference line DL2 printed at the above-mentioned transport speed Vf1 correspond to the "first line segment" in the present invention, and the first reference printed at the transport speed Vf2. The line DL1 and the second reference line DL2 correspond to the "second line segment" in the present invention. Further, the first reference line RL1 and the second reference line RL2 described above correspond to the "reference line segment" in the present invention.

Here, a specific process for detecting the inclination of the head 35 will be described with reference to FIG. Note that FIG. 14 is a flowchart showing the inclination detection adjustment process in the height direction.

Step S1
The operation unit 33 is operated to print the above-mentioned test chart TC while transporting the continuous paper WP at a low first transport speed (for example, transport speed Vf1 = 120 [mpm]).

Step S2
Among the test chart TCs printed on the continuous paper WP, visually check the second detection chart DT2 to determine whether or not the detection target line segment DL2 is inclined to the second reference line segment group RLG2. To do. Then, if there is an inclined object, the first detection chart DT1 corresponding to the second detection chart DT2 is magnified and observed with a loupe or the like. Then, with respect to the detection target line segment DL1 in the first detection chart DT1, the amount of inclination with respect to the first reference line segment group RLG1 is measured. As a result, the preset first threshold value is compared with the amount of inclination thereof, and if it is larger than the first threshold value, step S3 is performed.

Step S3
The amount of inclination according to the test chart printed at the low first transfer speed is the inclination of the head 35 in the width direction Y in the XY plane (see FIGS. 6 and 7). Therefore, the position of the head 35 in the transport direction X is adjusted by the adjusting pin 47 according to the amount of inclination, and the inclination of the head 35 in the width direction Y on the XY plane is eliminated.

Step S4
The operation unit 33 is operated to print the above-mentioned test chart TC while transporting the continuous paper WP at a second transport speed (for example, transport speed Vf2 = 180 [mpm]) which is higher than the first transport speed. Let me.

Step S5
Among the test chart TCs printed on the continuous paper WP, visually check the second detection chart DT2 to determine whether or not the detection target line segment DL2 is inclined to the second reference line segment group RLG2. To do. Then, if there is an inclined object, the first detection chart DT1 corresponding to the second detection chart DT2 is magnified and observed with a loupe or the like. Then, with respect to the detection target line segment DL1 in the first detection chart DT1, the amount of inclination with respect to the first reference line segment group RLG1 is measured. As a result, the preset second threshold value (> first threshold value) is compared with the inclination amount, and if it is larger than the second threshold value, step S6 is performed. Since the second threshold value is larger than the first threshold value, if the comparison in step S5 satisfies the condition (second threshold value> first threshold value), the detection target line segment DL1 printed at the second transport speed , DL2 indicates that the inclination of the detection target line segments DL1 and DL2 printed at the first transport speed is larger than the inclination of DL2.

Step S6
The amount of inclination according to the test chart printed at the high second transfer speed is the inclination of the head 35 in the height direction Z in the YZ plane (see FIGS. 8 and 9). Therefore, with respect to the head 35, the deviation amount Lg shown in FIG. 9 is measured, and the inclination amount M is obtained from the above equation (2). Then, after calculating the tilt amount M1 to be adjusted by the above equation (3), the position of the head 35 in the height direction Z is adjusted according to the tilt amount M1 to be adjusted. Specifically, a shim corresponding to the amount of inclination M1 to be adjusted is sandwiched between the head 35 and the module base plate 43 to adjust the position in the height direction Z.

According to this embodiment, when the slope of the detection target line segments DL1 and DL2 in the width direction Y orthogonal to the transport direction X is larger than the slope of the detection target line segments DL1 and DL2 printed at a slower transport speed. , Indicates that the head 35 has an inclination in the height direction Z. As a result, it is possible to detect whether or not there is an inclination of the head 35 in the height direction Z simply by printing the test chart TC line segment by changing the conveying speed.

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

(1) In the above-described embodiment, the configuration in which the printing unit 19 is fixed and the continuous paper WP is conveyed has been described as an example, but the present embodiment is not limited to such a configuration. That is, it can be applied even if the continuous paper WP is fixed and the printing unit 19 is moved.

(2) In the above-described embodiment, continuous paper WP is exemplified as the printing medium, but the present invention may be a printing medium other than continuous paper WP. Examples of the printing medium include single-cut paper (sheet-fed paper) and film.

(3) In the above-described embodiment, the test chart TC includes a first reference line segment group RLG1 and a second reference line segment group RLG2, but the present invention does not require them. For example, when a continuous paper WP in which ruled lines having a long axis in the width direction Y are drawn at predetermined intervals in the transport direction X is used, the first reference line segment group RLG1 and the second reference line segment group are displayed on the test chart TC. There is no need to draw RLG2. As a result, ink consumption can be suppressed in the tilt detection process.

(4) In the above-described embodiment, the first reference line segment group RLG1 and the second reference line segment group RLG2 are printed only on the nozzles 37 on both ends of the plurality of nozzles 37 of the head 35 except the central portion. However, in the present invention, as shown in the first modification of the detection chart of FIG. 15, the first reference line segment group RLG1 and the second reference line segment group RLG2 are formed by using all of the plurality of nozzles 37 of the head 35. It may be printed.

(5) In the above-described embodiment, the test chart TC includes a first detection chart DT1 and a second detection chart DT2, but the present invention is not limited to the test chart having such a configuration. For example, as shown in the second modification of the detection chart of FIG. 16, the configuration may be such that the detection chart DT is used. That is, the first reference line segment group RLG1 and the second reference line segment group RLG2 are printed centering on the same position in the transport direction X, and only one detection target line segment DL1 is printed. Even with such a configuration, the same effect as that of the above-described embodiment can be obtained, and the required length of the test chart TC in the transport direction X can be shortened, so that ink and continuous paper WP can be saved.

(6) In the above-described embodiment, the operator of the apparatus detects the inclination of the line segments DL1 and DL2 to be detected, but the inclination is automatically detected by image processing the test chart TC taken by the inspection unit 27. It may be configured to be used.

As described above, the present invention is suitable for detecting the height inclination of the head in the inkjet printing apparatus.

1 ... Inkjet printing system 3 ... Inkjet printing device 5 ... Paper feed unit 7 ... Paper ejection unit WP ... Continuous paper M1 to M4 ... 1st to 4th drive rollers 25 ... Base plate 31 ... Main control unit 33 ... Operation unit 35 ... Head 37… Nozzle 41… Head module 43… Module base plate 45… Insertion port 47… Adjustment pin 49… Fixing pin 51… Module insertion port 53… Locking pin L… Line segment M… Entanglement amount Vf… Transport speed Lg… Misalignment amount Vd ... Droplet velocity M1 ... Tilt amount to be adjusted TC ... Test chart PT ... Patch DT1 ... First detection chart DT2 ... Second detection chart RLG1 ... First reference line segment group RL1 ... First reference line DL1 ... Detection target line segment W1 ... First interval RLG2 ... Second reference line segment group RL2 ... Second reference line DL2 ... Detection target line segment W2 ... Second interval

Claims (6)

In a method for detecting the height inclination of a head in an inkjet printing apparatus that prints while moving a print head provided with a head for ejecting ink droplets and a print medium relative to each other.
A step of printing a first line segment in a direction orthogonal to the relative movement direction while the print head and the print medium are relatively moved at the first speed.
A step of printing a second line segment in a direction orthogonal to the relative moving direction while the print head and the printing medium are relatively moved at a second speed faster than the first speed.
When the inclination of the second line segment in the direction orthogonal to the relative moving direction is larger than the inclination of the first line segment, the step of determining that the head has an inclination in the height direction and
A method for detecting the height inclination of a head in an inkjet printing apparatus. In the method for detecting the height inclination of the head in the inkjet printing apparatus according to claim 1,
After the step of printing the first line segment and before the step of printing the second line segment,
A step of determining whether or not the inclination of the first line segment in a direction orthogonal to the relative movement direction has an inclination of the first threshold value or more.
When the inclination of the first line segment has an inclination equal to or greater than the first threshold value, a step of adjusting the head so as to eliminate the inclination in the relative moving direction, and a step of adjusting the head.
A method for detecting the height inclination of a head in an inkjet printing apparatus. In the method for detecting the height inclination of the head in the inkjet printing apparatus according to claim 1 or 2.
A head different from the head and attached to the print head in a state where there is no height inclination is used as a reference head.
Before the step of printing the first line segment and before the step of printing the second line segment, the reference head prints the reference line segment on the printing medium in a direction orthogonal to the relative moving direction. Carry out the process of
A method for detecting a height inclination of a head in an inkjet printing apparatus, wherein the first line segment and the second line segment are printed in close proximity to the reference line segment, respectively. In the method for detecting the height inclination of the head in the inkjet printing apparatus according to claim 3.
In an inkjet printing apparatus, the reference line segment is printed only by a plurality of nozzles located on both ends in a direction orthogonal to the relative moving direction among a plurality of nozzles included in the reference head. Head height tilt detection method. In the method for detecting the height inclination of the head in the inkjet printing apparatus according to claim 3 or 4.
The reference line segment is printed in two lines with a first interval in the relative movement direction, a first reference line segment group, and a second reference line segment wider than the first interval. With a second reference line segment
The first line segment and the second line segment are printed at the first interval and the second interval.
The second interval is an interval in which the positional relationship between the first line segment and the second line segment and the first reference line segment group can be visually recognized, and the first interval is the first interval. A method for detecting the height inclination of a head in an inkjet printing apparatus, wherein the positional relationship between the line segment and the second line segment and the second reference line segment group is an interval that can be visually recognized by an enlarging means. In the method for detecting the height inclination of the head in the inkjet printing apparatus according to claim 1 or 2.
A method for detecting a height inclination of a head in an inkjet printing apparatus, wherein the printing medium has a ruled line in a direction orthogonal to the relative moving direction.

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