JP7490230B2 - Inkjet Printing Device - Google Patents

Description

The present invention relates to an inkjet printing device capable of printing on the outer surface of rod-shaped members with a long axial length, such as walking sticks, poles, bars, rods, poles, pipes, and other cylindrical objects.

There are inkjet printing devices that perform inkjet printing on the outer peripheral surface of a cylindrical recording medium (see, for example, Patent Document 1).

JP 2012-527387 A

The conventional inkjet printing device configuration for printing on recording media such as cylinders and columns, as disclosed in Patent Document 1, is intended for printing on recording media that do not require printing over an area significantly wider than the printable width of a single inkjet head. For example, recording media such as cans, cups, jars, and bottles are envisioned (see, for example, paragraph 0005 of Patent Document 1).

However, when printing on all or part of the outer surface of a rod-shaped member such as a cane, pole, stick, bar, rod, pole, pipe, or other cylinder or columnar member that has an axial length significantly longer than the printable width of the inkjet head, the following problems are anticipated.

That is, when printing the outer peripheral surface of a recording medium such as a cylinder or columnar body using the inkjet method, it is assumed that the recording medium is rotated in the axial direction while ink is ejected from an inkjet head onto the outer peripheral surface for printing. However, there is a limit to the printable width of a typical inkjet head. Therefore, when attempting to print a rod-shaped member whose axial length is significantly longer than the printable width of the inkjet head, the rod-shaped member is rotated in the axial direction while the inkjet head, which has a limited printable width, and the significantly long rod-shaped member are moved relative to each other in the axial direction to print, which significantly increases the printing time and can cause problems with production takt time.

The present invention has been made in consideration of the above problems, and aims to provide an inkjet printing device that solves the above problems and can efficiently and quickly print on the outer peripheral surface of a rod-shaped member that has a long axial length, such as a walking stick, pole, bar, rod, pole, pipe, or other cylindrical body.

In order to achieve the above objective, the inventors of the present invention have, through extensive ingenuity, discovered the following configuration.

That is, in the present invention, an inkjet printing apparatus that performs inkjet printing on an outer peripheral surface of a rod-shaped member includes:
a holding and rotating unit that rotatably holds the rod-shaped member;
a first carriage on which a plurality of inkjet heads, each having a nozzle surface on which a plurality of nozzles for ejecting ink are arranged in a predetermined direction, are mounted at first intervals, which are predetermined intervals, in a rotation axis direction along which a rotation axis of the rod-shaped member that is held and rotated by the holding and rotating unit extends;
a first carriage moving means for moving the first carriage in the rotation axis direction,
an ink applying operation for applying ink by ejecting ink from the plurality of inkjet heads to an outer peripheral surface of the rod-shaped member rotated around the rotation axis by the holding and rotating unit, and a first carriage moving operation for moving the first carriage a first distance, which is a predetermined distance, in the direction of the rotation axis by the first carriage moving means, are repeatedly performed;
The ink applying operation includes an operation of simultaneously ejecting ink from a plurality of the inkjet heads to apply ink to the outer circumferential surface of the rod-shaped member.

In the inkjet printing apparatus of the present invention, the nozzle surface has a nozzle configuration portion in which the plurality of nozzles are arranged in the predetermined direction at a nozzle interval that is a predetermined interval,
The first interval is approximately equal to an integer multiple of the nozzle interval.

In the inkjet printing apparatus of the present invention, the ink applying operation is performed by rotating the rod-shaped member by the holding and rotating unit a predetermined amount of rotation, and using recording areas corresponding to some or all of the plurality of nozzles of the nozzle configuration unit, recording an area on the outer circumferential surface of the rod-shaped member in the direction of the rotation axis, the area having a length corresponding to the direction of the rotation axis of the recording area and corresponding to the predetermined amount of rotation,
The first interval is approximately equal to an integer multiple of the length of the recording area in the direction of the rotation axis.

Furthermore, in the inkjet printing device of the present invention, the first interval is approximately equal to an integer multiple of the length of the nozzle component in the rotational axis direction.

Furthermore, in the inkjet printing device of the present invention, the first distance is approximately equal to the length of the recording area in the rotation axis direction.

The inkjet printing device of the present invention is also characterized in that, among the multiple inkjet heads mounted on the first carriage, the ink application operation is started sequentially from the inkjet head that has reached a position where the rod-shaped member faces the nozzle surface by the first carriage movement operation.

Furthermore, in the inkjet printing device of the present invention, the holding and rotating unit is characterized by having a function of changing the angle at which the rod-shaped member is held depending on the angle of gradient of the outer peripheral surface of the rod-shaped member relative to the central axis of the rod-shaped member so that the nozzle surface and the outer peripheral surface of the rod-shaped member are approximately parallel.

The inkjet printing device of the present invention is characterized in that it has a support member for supporting the rod-shaped member held by the rotating holding unit and restricting movement of the rod-shaped member in a direction approximately perpendicular to the axial direction, and the support member has a mechanism for moving the rod-shaped member held by the rotating holding unit in a direction approximately perpendicular to the axial direction according to the diameter of the rod-shaped member.

In addition, the inkjet printing apparatus according to the present invention further includes a second carriage having an actinic ray irradiation device mounted thereon, the actinic ray irradiation device having a light ray irradiation surface that irradiates the ink applied to the rod-shaped member with actinic ray for curing the ink;
a second carriage moving means connected to the second carriage for moving the second carriage in the rotation axis direction;
the second carriage is disposed so that the light beam irradiation surface faces the rod-shaped member held by the holding and rotating unit;
The ink supply device is characterized in that, simultaneously with or after the ink supply operation is completed, an actinic ray irradiation operation in which the actinic ray is irradiated from the light irradiation surface and a second carriage movement operation in which the second carriage is moved in the direction of the rotation axis by the second carriage movement means are repeated.

In the inkjet printing apparatus according to the present invention, a plurality of the actinic radiation irradiation devices are arranged on the second carriage at second intervals, which are predetermined intervals, in the direction of the rotation axis,
The second carriage moving means is characterized in that, simultaneously with or after completion of the first carriage moving operation, it moves the second carriage in the direction of the rotation axis so that the nozzle surface of the inkjet head performing the ink application operation and the light irradiation surface of any one of the multiple active light irradiation devices are in a positional relationship facing each other via the rod-shaped member held by the holding and rotating unit.

In the inkjet printing apparatus according to the present invention, the second carriage moving means performs an operation of moving the second carriage by the first distance in a direction in which the first carriage moves due to the first carriage movement operation;
and performing an operation of moving the second carriage by the first distance in a direction opposite to a direction in which the first carriage moves due to the first carriage movement operation.

Furthermore, in the inkjet printing device of the present invention, the second carriage is characterized by having a function of changing the distance between the outer circumferential surface of the rod-shaped member and the light irradiation surface according to the angle of the gradient of the rod-shaped member.

Furthermore, in the inkjet printing device of the present invention, the actinic ray irradiation device is characterized by having an irradiation area limiting unit for limiting the irradiation area of the actinic ray.

Furthermore, in the inkjet printing device of the present invention, the second carriage is arranged so that the light beam irradiation surface faces the rod-shaped member and the nozzle surface held by the holding and rotating unit.

Furthermore, the inkjet printing device of the present invention is characterized in that the first carriage is further equipped with an actinic light irradiation device.

By adopting the above configuration, the present invention has been able to solve the above problems and provide an inkjet printing device that can efficiently and quickly print on the outer peripheral surface of a rod-shaped member that has a long axial length, such as a walking stick, pole, bar, rod, pole, pipe, or other cylindrical object.

1 is an overall view of an inkjet printing apparatus according to an embodiment of the present invention; 4 is a schematic bottom view of the first carriage as viewed from the nozzle surface side of the inkjet head. FIG. 6A and 6B are schematic diagrams illustrating angle adjustment of a first carriage, a holding and rotating unit, and a second carriage. FIG. 2 is a schematic perspective view showing a configuration example of an irradiation area limiting unit of the active light irradiation device. 1 is a block diagram showing an electrical configuration of an inkjet printing apparatus according to an embodiment of the present invention; 2 is a schematic side view showing the positional relationship between a first carriage, a holding and rotating unit, and a second carriage in an inkjet printing apparatus according to an embodiment. FIG. 4 is a flowchart showing a printing sequence by an inkjet printing apparatus according to an embodiment of the present invention. 5A and 5B are schematic diagrams showing an example of relative movement between a first carriage and a second carriage when a print sequence is executed.

The following describes an embodiment of the present invention in detail with reference to the drawings.

The configuration of an inkjet printing device according to an embodiment of the present invention will be described with reference to FIG. 1.

FIG. 1 is an overall view showing the overall configuration of an inkjet printing device according to an embodiment of the present invention. As shown in FIG. 1, the inkjet printing device 1 has a plurality of inkjet heads 21 capable of ejecting ink of different colors mounted on a first carriage 31. FIG. 1 shows an example in which four inkjet heads 21 are mounted on the first carriage 31.

The inkjet heads 21 are usually mounted on the first carriage 31 to eject four colors of ink, cyan (C), magenta (M), yellow (Y), and black (K), corresponding to the number of inks. In addition, the first carriage 31 can also be equipped with additional inkjet heads 21 for ejecting special color inks such as white (W) and clear (CL) required for the required image formation, as necessary, or can be omitted if multiple colors are not required. Furthermore, the inkjet heads 21 may be one that can eject one color of ink, or one that can eject two or more different colors of ink (multi-color ink compatible head) as necessary.

The ink ejected from the inkjet head 21 can be selected from actinic radiation curable ink, solvent ink, water-based ink, oil-based ink, etc., depending on the properties of the recording medium. In this embodiment, actinic radiation curable ink is used. Also, in this embodiment, among actinic radiation curable inks, ultraviolet ray curable ink is used.

Figure 2 is a schematic bottom view of the first carriage 31 viewed from the nozzle surface 23 side of the inkjet head 21.

The inkjet head 21 has a nozzle surface 23 including a nozzle configuration section 25 in which nozzles 27 for ejecting ink are arranged in a predetermined row in the nozzle row direction. As shown in FIG. 2, each of the multiple inkjet heads 21 mounted on the first carriage 31 is arranged in the nozzle row direction so that each of the nozzle configuration sections 25 is spaced apart at a predetermined first interval L1. In this embodiment, the nozzle row direction is configured to approximately coincide with the direction of the rotation axis of the rod-shaped member 3 that is held and rotated by the holding and rotating unit 41 described below. The relative positions of the multiple inkjet heads 21 arranged on the first carriage 31 will be described in detail later.

The first carriage 31 may be configured to mount the inkjet heads 21 on one carriage as described above, or may be configured, for example, to mount one inkjet head 21 on one carriage and have the nozzle components 25 of the inkjet heads 21 mounted on each carriage arranged with the first distance L1 between them, or may have another configuration in which the nozzle components 25 are arranged with the first distance L1 between them.

A first carriage moving means 33 is connected to the first carriage 31 for moving the first carriage 31 in the X-axis direction, which is the nozzle row direction. The first carriage moving means 33 preferably uses a linear motor, which is a drive system that moves linearly, in order to move the first carriage 31 in the nozzle row direction by driving it. As the linear motor, a linear motor, a ball screw, a timing belt, or other suitable motor is used. In this embodiment, a linear motor is used. In addition, the first carriage moving means 33 preferably includes a sensor such as an encoder for identifying the origin of the first carriage 31 and confirming the current position.

Furthermore, it is preferable that the first carriage 31 is provided with a first carriage up-down movement means 34 for moving the first carriage 31 in the Z-axis direction, which is a direction substantially perpendicular to the X-axis direction, by driving the first carriage 31 so that the distance between the outer circumferential surface of the rod-shaped member 3 and the nozzle surface 23 can be adjusted. A servo motor, a stepping motor, or the like is appropriately used for the first carriage up-down movement means 34. It is preferable that the Z-axis movement means is provided with a brake means to prevent it from falling.

As described above, in the inkjet printing device 1 of this embodiment, the first carriage 31 is connected to the first carriage moving means 33, and the first carriage 31 is moved in the X-axis direction, which is the axial direction of the rod-shaped member 3, thereby moving the inkjet 21 and the rod-shaped member 3 relative to each other in the axial direction. The purpose of adopting such a configuration will now be explained.

If the inkjet head 21 is not moved, but the rod-shaped member 3 itself is moved in the axial direction, and the inkjet head 21 and the rod-shaped member 3 are moved relative to each other in the axial direction of the rod-shaped member 3, the following problems may occur in the transportation (material handling) of the rod-shaped member 3.

In other words, in order to perform printing by moving the rod-shaped member 3 and the inkjet head 21 relatively from one end to the other end in the axial direction (X-axis direction) of the rod-shaped member 3, the rod-shaped member 3 needs to be structured so that it can be transported in the X-axis direction a length that is at least twice the axial length of the rod-shaped member 3. If it is necessary to print on a long rod-shaped member 3, problems such as an increase in size of the inkjet printing device 1 may arise.

In addition, if the rod-shaped member 3 used in the inkjet printing device 1 according to this embodiment is a thin and elastic member, the load applied to the rod-shaped member 3 during transportation may cause bending or shaking in a direction approximately perpendicular to the axial direction of the rod-shaped member 3. This may cause unevenness in the distance between the nozzle surface 23 of the inkjet head 21 and the outer circumferential surface of the rod-shaped member 3. Such unevenness in the distance may cause problems such as deterioration of print image quality and contact between the nozzle surface 23 and the outer circumferential surface of the rod-shaped member 3.

Therefore, by configuring the first carriage 31 to move in the axial direction of the rod-shaped member 3 to move the inkjet 21 and the rod-shaped member 3 relative to each other in the axial direction, and by ensuring space for the first carriage 31 to move relatively in the axial direction of the rod-shaped member 3 at least the axial length of the rod-shaped member 3, ink can be applied from one end of the rod-shaped member 3 to the other end in the axial direction. Furthermore, the above-mentioned bending and vibration caused by the transport of the rod-shaped member 3 can also be prevented.

A holding and rotating unit 41 is arranged below the first carriage 31 in the Z-axis direction to hold the rod-shaped member 3, which is the recording medium, and rotate it around its axis when printing is performed on the outer peripheral surface of the rod-shaped member 3.

A rotation motor 42 is connected to the holding and rotating unit 41, and the rotation drive of the motor rotates the rod-shaped member 3 held by the holding and rotating unit 41. An appropriate motor such as a servo motor or a stepping motor can be selected as the rotation motor 42.

The method of holding the rod-shaped member 3 by the holding and rotating unit 41 is selected appropriately depending on the shape of the rod-shaped member 3. A method that can securely fix the rod-shaped member 3 is selected according to the rod-shaped member 3, such as a method of suspending the rod-shaped member 3 and clamping its axial end, or a method of fixing it with a vacuum chuck using air suction.

Furthermore, when the outer peripheral surface of the rod-shaped member 3 has a gradient, such as when the rod-shaped member 3 is conical or truncated conical, a mechanism can be provided that can adjust the holding angle of the rod-shaped member 3 according to the gradient so that the distance between the outer peripheral surface of the rod-shaped member 3 and the nozzle surface 23 of the inkjet head 21 is uniform. Note that the gradient here refers to the interior angle between a line passing through the axial center of the rod-shaped member 3 and a line (generator) passing through the outer peripheral surface of the rod-shaped member 3 in the direction of the central axis of the rod-shaped member 3.

As shown in FIG. 1, in this embodiment, one end of the holding and rotating unit 41 is provided with a vertical movement means 43 for moving one end of the rod-shaped member 3 in the Z-axis direction. In addition, the other end of the holding and rotating unit 41 is provided with a pivot 44 for rotating the rod-shaped member 3 up and down in the Z-axis direction around the other end. By driving the vertical movement means 43 and rotating the rod-shaped member 3 in the Z-axis direction around the pivot 44, the holding angle of the rod-shaped member 3 is adjusted, and the distance between the outer circumferential surface of the rod-shaped member 3 and the nozzle surface 23 is adjusted.

Figure 3 is a schematic diagram showing the relationship between the angle adjustment of the first carriage 31, the holding and rotating unit 41, and the second carriage 51, and an example of adjusting the holding angle of the rod-shaped member 3 will be explained based on Figure 3.

For example, as shown in Figure 3, when the gradient of the outer peripheral surface of the inclined rod-shaped member 3 is an angle θ, the vertical movement means 43 is operated to move one end of the rod-shaped member 3 by θ in a direction approaching the nozzle surface 23 in the Z-axis direction, thereby adjusting the angle so that the interior angle between a line passing through the nozzle surface 23 of the inkjet head 21 in the nozzle row direction and a line passing through the axial center of the rod-shaped member 3 is θ. As a result, the nozzle surface 23 and the X-axis direction of the outer peripheral surface of the rod-shaped member 3 become approximately parallel.

By performing the above angle adjustment, even if the rod-shaped member 3 has a slope on its outer circumferential surface, it is possible to maintain a constant distance between the nozzle surface 23 of the inkjet head 21 and the outer circumferential surface of the rod-shaped member 3 while avoiding contact between the two, thereby enabling high-quality printing to be achieved.

Furthermore, it is preferable that the holding and rotating unit 41 is provided with a holding and rotating unit moving means 45 for moving the holding and rotating unit in the X-axis direction at one or both ends of the holding and rotating unit 41 so that the rod-shaped member 3 can be suspended and held from one end to the other end of the holding and rotating unit 41 depending on the axial length of the rod-shaped member 3. In this embodiment, the holding and rotating unit moving means 45 is provided so that one end of the holding and rotating unit 41 can be moved within a range of X2 in the X-axis direction. An appropriate linear motor is applied to the holding and rotating unit moving means 45.

The holding and rotating unit 45 may also be provided with a vibration suppression unit 46 to prevent vibration that occurs when the rod-shaped member 3 is rotated in the axial direction, depending on the material of the rod-shaped member 3. In this embodiment, the vibration suppression unit 46 is brought into contact with the outer peripheral surface of the rod-shaped member 3, thereby suppressing vibration in a direction approximately perpendicular to the axial direction of the rod-shaped member 3 that occurs due to centrifugal force generated when the rod-shaped member 3 is rotated. Furthermore, in order to adjust the contact condition between the rod-shaped member 3 and the vibration suppression unit 46 depending on the length and diameter of the rod-shaped member 3, this embodiment is provided with a first vibration suppression unit moving means 47 and a second vibration suppression unit moving means 48.

Furthermore, one or more active light irradiation devices 53 having a light irradiation surface 54 for irradiating active light are mounted below the holding and rotating unit 41 in the Z-axis direction so that the rod-shaped member 3 held by the holding and rotating unit 41 faces the light irradiation surface 54 (see Figure 4).
When a plurality of actinic ray irradiation devices 53 are arranged, they are mounted on the second carriage 51 side by side in the nozzle row direction at a predetermined second interval.

In this embodiment, the active light irradiation device 53 mounted on the second carriage 51 is used to temporarily cure the ink applied to the outer peripheral surface of the rod-shaped member 3, thereby limiting the spreading of the ink on the outer peripheral surface of the rod-shaped member 3 and ensuring a predetermined image quality.

The actinic radiation irradiation device 53 can be selected from ultraviolet radiation irradiation devices, electron beam devices, and other devices appropriate for the properties of the actinic radiation curable ink used, but in this embodiment, an ultraviolet radiation irradiation device is used correspondingly to the ultraviolet radiation curable ink used. In addition, the lamp used in the ultraviolet radiation irradiation device can be selected from an appropriate type, such as mercury, metal halide, or LED. In this embodiment, an LED is used for compactness and ease of handling, but this is not limited to this.

Here, we will explain how to set the second interval, which is the spacing between each of the active light irradiation devices when multiple active light irradiation devices 53 are arranged on the second carriage 51.

When the first carriage 31 and the second carriage 51 are positioned opposite each other, it is desirable to position the multiple active light irradiation devices 53 mounted on the second carriage 51 so that the nozzle surfaces 23 of all the inkjet heads 21 mounted on the first carriage 31 face each other with their light irradiation surfaces 54 of the multiple active light irradiation devices 53 mounted on the second carriage 51.

Therefore, in this embodiment, when the first carriage moving means 33 and the second carriage moving means 55 are driven to move the first carriage 31 and the second carriage 51, the second interval is set so that the center line in the X-axis direction of the inkjet head 21 and the center line in the X-axis direction of the opposing active light irradiation device 53 are in a positional relationship that approximately coincides, and each of the nozzle surfaces 23 of the multiple inkjet heads 21 mounted on the first carriage 31 and each of the light irradiation surfaces 54 of the multiple active light irradiation devices 53 mounted on the second carriage 51 are positioned so as to face each other.

By setting the second interval as described above, the ink deposited by each inkjet head 21 can be efficiently irradiated with active light by each active light irradiation device 53.

The second carriage 51 may be configured to mount the active light irradiation devices 53 on one carriage as described above, or may be configured, for example, to mount one active light irradiation device 53 on one carriage and arrange the active light irradiation devices 53 mounted on each carriage at a second interval, or may have another configuration in which the active light irradiation devices 53 are arranged at a second interval.

In addition, each active light irradiation device 53 is equipped with an irradiation area limiting unit 57 that limits the irradiation area of the active light to suppress irradiation of the active light to the nozzle surface 23 of the inkjet head 21.

Figure 4 is a schematic perspective view showing an example of the configuration of an irradiation area limiting unit of an active light irradiation device.

In this embodiment, as the irradiation area limiting unit 57, a plate-shaped light-shielding plate having slits for limiting the irradiation area is installed on the side of the light irradiation surface 54 of the active light irradiation device 53. Note that the configuration of the irradiation area limiting unit is not limited to this, and it is also possible to configure the light-shielding plate to be movable so that the range that can be limited can be adjusted.
The irradiation area limiting unit 57 functions to limit the irradiation area of the light beam, so that on the one hand the outer peripheral surface of the rod-shaped member 3 is irradiated with the active light beam, and on the other hand the irradiation of the active light beam to the nozzle surface 23 of the inkjet head 21 is limited. This makes it possible to avoid damage to the inkjet head 21 due to nozzle clogging, etc., which occurs when the ink attached to the nozzle surface 23 of the inkjet head 21 is unintentionally cured due to the irradiation of the active light beam to the nozzle surface 23 of the inkjet head 21.

A second carriage moving means 55 for moving the second carriage 51 in the nozzle row direction is connected to the second carriage 51. The second carriage moving means 55 preferably uses a linear motor, which is a drive system that moves linearly, in order to move the second carriage 51 in the nozzle row direction by driving the second carriage moving means 55. As the linear motor, a linear motor, a ball screw, a timing belt, or any other suitable device is used.

In this embodiment, a linear motor is used. In addition, it is preferable that the second carriage moving means 55 has a built-in sensor such as an encoder for determining the origin of the second carriage 51 and checking the current position.

Furthermore, if uniformity of the accumulated light amount of the active light irradiated from each of the mounted active light irradiation devices 53 on the outer peripheral surface of the rod-shaped member 3 is required, the second carriage 51 can be provided with a function for changing the distance from the outer peripheral surface of the rod-shaped member 3 to the light irradiation surface 54, such as an angle adjustment servo motor, in accordance with the angle of the gradient of the outer peripheral surface of the rod-shaped member 3, in the second carriage moving means 55. If there is no such requirement, it may be omitted as appropriate. In this embodiment, for angle adjustment, up-down moving means 43 is mounted that can move both ends of the second carriage 51 in the Z-axis direction.

An example of angle adjustment of the second carriage moving means 55 will be described with reference to FIG. 3. When the angle of the gradient of the outer peripheral surface of the rod-shaped member 3 is θ, and the holding angle of the rod-shaped member 3 is adjusted using the above method, the angle between the outer peripheral surface of the rod-shaped member 3 and the light beam irradiation surface 54 becomes 2θ, which is twice the angle of the gradient of the rod-shaped member 3.

Then, the distance change function is used to operate the vertical movement means 43 so that the angle of the light irradiation surface 54 side of the second carriage 51 becomes approximately parallel to the outer circumferential surface of the rod-shaped member 3, and one end of the second carriage 51 moves 2θ closer in the direction of the outer circumferential surface of the rod-shaped member 3. By performing such an angle adjustment operation, the linear distance between the outer circumferential surface of the rod-shaped member 3 and the light irradiation surface 54 of the active light irradiation device 53 can be kept approximately uniform, and attenuation of the active light caused by the distance and contact between the rod-shaped member 3 and the active light irradiation device 53 can be avoided.

In addition to the inkjet head 21, the first carriage 31 may also be equipped with an actinic ray irradiation device as necessary. In this embodiment, an actinic ray irradiation device 35 for main curing is mounted on the upstream side of the first carriage 31 in the printing direction shown in FIG. 1. In this embodiment, the actinic ray irradiation device 35 for main curing is used to completely cure the ink applied to the outer peripheral surface of the rod-shaped member 3 by irradiating actinic ray.

As with the actinic ray irradiation device 53, the main curing actinic ray irradiation device 35 can be an ultraviolet ray irradiation device, an electron beam device, or any other suitable device selected depending on the properties of the actinic ray curable ink used, but in this embodiment, an ultraviolet ray irradiation device is used to accommodate the use of ultraviolet ray curable ink.

Furthermore, the first carriage 31 may be provided with a height detection means 36 such as a laser sensor, and may be equipped with a function for measuring the distance between the nozzle surface 23 and the outer peripheral surface of the rod-shaped member 3, and a function for recognizing the type of rod-shaped member 3 being held.

Here, we will explain the positional relationship between the first carriage 31, the holding and rotating unit 41, and the second carriage 51 when viewed from the nozzle row direction.

Figure 6 is a schematic side view showing the positional relationship between the first carriage 31, the holding and rotating unit 41, and the second carriage 51 in the inkjet printing device 1 according to this embodiment.

The nozzle surface 23 of the inkjet head 21 mounted on the first carriage 31 and the light irradiation surface 54 of the active light irradiation device 53 mounted on the second carriage 51 are in a positional relationship facing each other. Therefore, in order to prevent the ink attached to the nozzle surface 23 of the inkjet head 21 from being hardened by the active light 58 irradiated from the active light irradiation device 53 being irradiated to the nozzle surface 23 of the inkjet head 21 as described above and damaging the inkjet head 21, it is preferable that the nozzle surface 23 of the inkjet head 21 and the light irradiation surface 54 of the active light irradiation device 53 are in a position facing each other, and the holding and rotating unit 41 is arranged so that the outer peripheral surface of the held rod-shaped member 3, the nozzle surface 23, and the light irradiation surface 54 all face each other. As a result, the active light 58 irradiated from the light irradiation surface 54 is irradiated to the rod-shaped member 3 held by the holding and rotating unit 41, and the active light 58 irradiated to the nozzle surface 23 of the inkjet head 21 is limited by the rod-shaped member 3.

Next, the electrical configuration of the inkjet printing device 1 according to this embodiment will be described with reference to FIG. 5.

Figure 5 is a block diagram showing the electrical configuration of the inkjet printing device 1.

The inkjet printing device 1 in this embodiment includes a control computer 60. The control computer 60 includes, for example, a CPU and a memory. The memory is composed of, for example, RAM and ROM, and the RAM temporarily stores the results of CPU calculations and print image data. The ROM also stores an execution program for the printing sequence, as well as control programs for driving and controlling the inkjet head 21 and various motors.

The control computer 60 is connected to the controller 61 via an interface such as a LAN, and communicates with the controller 61 via this interface. The controller 61 may be, for example, a programmable controller (PLC), and controls the various drivers that are connected to it. It also receives signals from various sensors.

The controller 61 receives commands from the control computer 60 and drives and controls the linear motor 63 constituting the first carriage moving means 33 via a motor driver 62, and drives and controls the linear motor 65 constituting the second carriage moving means 55 via a motor driver 64. It also drives and controls the rotation motor 42 constituting the holding and rotating unit 41 via a drive driver 66. The controller 61 also receives commands from the control computer 60 and controls the operation of the active light irradiation device 53 and the like via a driver 68.

Furthermore, the head control board 69 receives commands from the control computer 60 and controls the ink ejection from the inkjet head 21.

Here, the relative positions of the multiple inkjet heads 21 arranged on the first carriage 31 will be described in detail with reference to Figure 2.

Figure 2 is a schematic bottom view showing the spacing of multiple inkjet heads mounted on the first carriage. As shown in Figure 2, multiple inkjet heads 21 are arranged on the first carriage 31 along the nozzle row direction, with each nozzle component 25 of each inkjet head 21 spaced at a first spacing L1.

The nozzle surface 23 of the inkjet head 21 has a nozzle configuration section 25 in which nozzles 27 for ejecting ink are arranged in a predetermined row, that is, a nozzle row direction, at a predetermined nozzle interval L3.

Furthermore, the nozzle configuration portion 25 has a nozzle length L2, which is the length over which the nozzles are arranged in the nozzle row direction from one end to the other end of the nozzle configuration portion 25.

Here, the nozzle spacing L3 will be explained. Nozzle spacing L3 refers to the spacing between adjacent nozzles in the inkjet head 21 used in the inkjet printing device 1, which is set so that printing can be performed at a specified resolution. Note that resolution refers to the number of ink dots per unit length that are ejected and applied from the inkjet head, and is generally defined as the number of ink dots applied per inch (25.4 mm). For example, if 300 ink dots are applied per inch, the print resolution is defined as 300 DPI, if 360 dots are applied, then 360 DPI, if 600 dots are applied, then 600 DPI, and if 1200 dots are applied, then 1200 DPI, but the resolution that can be selected is not limited to these.

The nozzle spacing L3 is set according to the required resolution, for example, approximately 84.6 μm at 300 DPI, approximately 70.5 μm at 360 DPI, approximately 42.3 μm at 600 DPI, and approximately 21.16 μm at 1200 DPI.

Based on the above, we will now explain how to set the first distance L1, which is the distance between each of the nozzle components 25 of each of the multiple inkjet heads 21.

In inkjet printing, ink dots of each color ejected from multiple inkjet heads 21 are combined on the surface of the recording medium to form an image using process colors. Therefore, when printing is performed using multiple inkjet heads 21, if the spacing between the ink dots ejected from each inkjet head 21 and formed on the surface of the recording medium is misaligned, it is not possible to form an image with the intended specified resolution, resulting in a deterioration in print quality.

Therefore, when the first carriage 31 is moved in the printing direction by a first distance described below and ink is applied to the outer peripheral surface of the rod-shaped member 3 by the multiple inkjet heads 21, it is necessary to position each of the inkjet heads 21 so that the spacing between the ink dots formed on the recording medium by the multiple inkjet heads 21 does not shift.

Therefore, it is preferable that the first spacing L1 of each of the multiple inkjet heads 21 is approximately equal to at least an integer multiple of the nozzle spacing L3. This prevents deviations in the positions at which ink dots are formed by each inkjet head 21, achieving high-quality printing.

Furthermore, due to the structure of the inkjet head 21, the length of the nozzle surface 23 in the nozzle row direction may be longer than the nozzle length L2, which is the length of the nozzle configuration portion 25 in the nozzle row direction. In this case, it is expected that it will be difficult to arrange the nozzle spacing L3 so that the first spacing L1 is approximately equal to the nozzle spacing L3 (for example, an arrangement in which the nozzle configuration portions 25 of each inkjet head 21 are approximately adjacent to each other). A method for setting the first spacing L1 in this case will be described below.

First, in inkjet printing, there are two methods for forming an image: the single-pass method, in which the number of prints required to form one image is not divided and all the necessary ink dots are formed in one go, and the multi-pass method, in which the number of prints required to form one image is divided and all the necessary ink dots are formed in multiple passes.

Here, the single pass method refers to a method in which the rod-shaped member 3 is rotated a predetermined amount (for example, once) around the inkjet head 21 with nozzle length L2, and during this rotation, a recording area (nozzle configuration part 25) corresponding to the nozzle length L2 is used to record an area on the outer circumferential surface of the rod-shaped member 3 that is a length of L2 in the axial direction of the rod-shaped member 3 and corresponds to a predetermined amount of rotation, and after recording of that area is completed, the inkjet head 21 is moved relatively in the axial direction of the rod-shaped member 3 by the length of the nozzle length L2, and this recording and this relative movement are repeated.

The multi-pass method is a method in which the recording area of the inkjet head 21 with nozzle length L2 is divided into N (2≧) areas, the rod-shaped member 3 is rotated a predetermined amount N times around the inkjet head 21, and in each rotation, the inkjet head 21 uses the N divided recording areas of the inkjet head 21 in sequence to record an area on the outer surface of the rod-shaped member 3 in the nozzle row direction, the area being L2/N in the axial direction of the rod-shaped member 3 and corresponding to a predetermined amount of rotation, and after the recording is completed, the inkjet head 21 is moved relatively in the axial direction of the rod-shaped member 3 by the nozzle length L2/N, and the recording and the relative movement are repeated.

Therefore, the first interval L1 of each inkjet head 21 can be made to approximately match an integer multiple of the nozzle length L2 (L2/N) divided according to the number of passes. This makes it possible to print without misalignment of the intervals between each of the ink dots formed on the recording medium by the multiple inkjet heads 21, even when printing is performed while moving the first carriage 31 in the nozzle row direction a distance equivalent to the nozzle length L2 divided according to the number of passes.

Furthermore, the first interval L1 of each inkjet head 21 can be set to approximately match an integer multiple of the nozzle length L2. This not only makes it possible to set the first interval L1 to approximately match an integer multiple of the nozzle interval L3, but also makes it possible to perform both single-pass and multi-pass printing without implementing complex control of the inkjet head 21.

Next, the printing sequence for the rod-shaped member 3 by the inkjet printing device 1 according to this embodiment will be described with reference to Figures 7, 8, etc.

Figure 7 is a flowchart showing a printing sequence by the inkjet printing device 1, which is one embodiment of the present invention. A program corresponding to this flowchart is stored in the ROM of the computer 60, and the CPU of the computer 60 controls various devices in accordance with this program to execute the printing sequence, which will be described in detail below.

Figure 8 is a schematic diagram showing an example of the relative movement of the inkjet head mounted on the first carriage, the rod-shaped member, and the active light irradiation device mounted on the second carriage 51 when a printing sequence is being executed.

In FIG. 8 and the following description, the inkjet printing device 1 is configured such that the first carriage 31 is equipped with five inkjet heads 21, inkjet head 21A, inkjet head 21B, inkjet head 21C, inkjet head 21D, and inkjet head 21E, spaced apart by the nozzle length L2, in order from the print start position toward downstream in the printing direction, and the second carriage 51 is equipped with five active light irradiation devices 53, active light irradiation device 53A, active light irradiation device 53B, active light irradiation device 53C, active light irradiation device 53D, and active light irradiation device 53E, in order from the print start position toward downstream in the printing direction.

Furthermore, in this embodiment, an example of a printing sequence for single-pass printing will be used for explanation.

Note that this description is not limited to the above example, and multi-pass printing may be performed, the number of inkjet heads 21 and active light irradiation devices 53 may be increased or decreased as necessary, and the first distance L1 may be changed within the range described above.

First, the print start position movement sequence of flow 1 in FIG. 7 is performed. Before printing begins, the first carriage 31 and the second carriage 51 are each moved to a predetermined print start position. In this embodiment, the print operation start position is where the nozzle surface 23 of the inkjet head 21E and the light irradiation surface 54 of the active light irradiation device 53A face each other.

In this embodiment, the corresponding relationship between each of the light irradiation surfaces 54 of the actinic light irradiation devices 53A to 53E that face each of the nozzle surfaces 23 of the inkjet heads 21A to 21E is not fixed, but is changed as described below, making it possible to make the movement range of the second carriage 51 in the X-axis direction narrower than the movement range of the first carriage 31 in the X-axis direction.

This allows the necessary mechanisms, such as an inkjet head cleaning mechanism, to be efficiently arranged in the space generated below the first carriage 31 and outside the range of movement of the second carriage in the X-axis direction, thereby saving space in the inkjet printing device. Furthermore, this configuration allows the linear motor used as the second carriage movement means 55 to be made smaller by using one with a narrower range of movement, and necessary mechanisms can be mounted appropriately in the space secured by the smaller linear motor, thereby further saving space in the device. Note that this configuration example is not limited to this example, and different configurations may be used as necessary.

Printing starts from this print start position, and printing is performed in a specified printing area from one end to the other end of the outer periphery of the rod-shaped member 3, from upstream to downstream in the printing direction, as shown in Figure 8.

Next, the carriage movement sequence of flow 2 is performed. The first carriage 31 and the second carriage 51 are moved downstream in the printing direction by the first and second distances by driving the first carriage movement means 33 and the second carriage movement means 55 under the control of the controller 61 under the command of the control computer 60. When single-pass printing is performed in the configuration of this illustrative example, the first distance is a distance that is approximately equal to the nozzle length L2. Furthermore, the second distance is set to a distance that is equal to the first distance. Note that when multi-pass printing is performed, the first distance is a distance L2/N obtained by dividing the nozzle length L2 by a predetermined number of passes (N). Furthermore, the second distance is set to a distance that is equal to the first distance.

The carriage movement sequence moves the inkjet head 21E and the active light irradiation device 53A to a position facing the outer peripheral surface area of the rod-shaped member 3 where the ink application operation and the light irradiation operation should be performed.

Next, the ink application operation sequence of flow 3 is carried out. Ink is ejected from the inkjet head 21 onto the outer peripheral surface of the rod-shaped member 3, which rotates around its axis by the drive of the rotation motor 42 connected to the holding and rotating unit 41, during a predetermined number of rotations, and ink is applied. In this illustrative example, the ink application operation starts from the inkjet head 21E during the initial first scan.

More specifically, a sensor built into the holding and rotating unit 41 recognizes the origin position of the rotation direction of the outer circumferential surface of the rod-shaped member 3 to confirm the printing position, and based on this, image data stored in the control computer 60 is output to the head control board 69, which drives the inkjet head 21E to perform the ink deposition operation. The rotation of the rod-shaped member 3 may be continued from the start to the end of printing, or may be rotated only during the ink deposition operation or light irradiation operation.

Next, the light irradiation sequence of flow 4 is carried out. The outer peripheral surface of the rod-shaped member 3, which rotates around its axis due to the drive of the holding and rotating unit 41, is irradiated with active light from the active light irradiation device 53 while it rotates a predetermined amount, and the ink applied to the outer peripheral surface of the rod-shaped member 3 is temporarily cured. In the case of this illustrative example, light irradiation is started from the active light irradiation device 53A during the initial first scan.

More specifically, a sensor built into the holding and rotating unit 41 recognizes the origin position of the rotation direction of the outer circumferential surface of the rod-shaped member 3 to confirm the irradiation start position, and based on the confirmed position, the controller 61 controls to drive the active light irradiation device 53A and perform light irradiation.

After completing flow 4, first check whether the necessary ink application and light irradiation operations have been completed as shown in the flowchart.

If the necessary ink application and light irradiation operations have not been completed, proceed to the next confirmation step, and as shown in the flowchart, perform a carriage movement operation to confirm whether or not the inkjet head 21 that should perform ink application and the active light irradiation device 53 that should perform light irradiation are not in an opposing positional relationship.

If the confirmation result shows that the inkjet head 21 and the active light irradiation device 53 are not in such a positional relationship, the process returns to flow 2 and repeats the execution up to flow 4.

In this illustrative example, the inkjet head 21 and the active light irradiation device 53 are not in such a positional relationship when the second scan is performed, so the process returns to flow 2 and is repeated up to flow 4.

In contrast, if, at the start of the third scan in this illustrative example, the carriage movement sequence is returned to flow 2 and the first carriage 31 and the second carriage 51 are moved a first distance and a second distance downstream in the printing direction, respectively, the inkjet head 21E and the active light irradiation device 53A are positioned opposite each other, but there is no active light irradiation device 53 facing the inkjet head 21D, which should start the ink application operation next. In this state, if the ink application operation of flow 3 is performed by the inkjet head 21E and the inkjet head 21D, the ink discharged and applied from the inkjet head 21D in flow 4 cannot be provisionally cured by light irradiation.

Therefore, in this case, the positional relationship adjustment operation of flow 5 is performed. Taking the third scan of this explanatory example as an example, the first carriage 31 is moved a first distance downstream in the printing direction, while the second carriage 51 is moved a second distance upstream in the printing direction. By the positional relationship adjustment operation described above, the inkjet 21E and the active light irradiation device 53B, and the inkjet head 21D and the active light irradiation device 53A are positioned facing each other, solving the above problem.

When flow 5 is completed, return to flow 3, and execute flows 3 and 4 in sequence. In the example of the third scan, in the ink application operation sequence of flow 3, ink is ejected simultaneously from inkjet head 21D and inkjet head 21E to apply ink to the outer peripheral surface of rod-shaped member 3, and in the light irradiation operation sequence of flow 4, light irradiation is performed simultaneously from active light irradiation device 53A and active light irradiation device 53B. In this way, by operating multiple inkjet heads 21 and active light irradiation device 53 respectively to simultaneously perform ink application operations and light irradiation operations, a wider printing area can be printed at once, and the production takt time can be improved.

Then, according to the flowchart in Figure 7, steps 1 to 5 are repeated as appropriate to perform the printing operations of the fourth scan, the fifth scan, and so on.

After that, when the printing operation continues, the carriage movement operation ensures that the inkjet head 21 that should apply ink and the active light irradiation device 53 that should irradiate light are not in an opposing positional relationship.

In the example of Figure 8, when the ninth scan is performed, each of the inkjet heads 21A to 21E and each of the active light irradiation devices 53A to 53E are positioned opposite each other.

Therefore, from the 9th scan onwards, the carriage movement operation is performed again, and the positional relationship adjustment operation of flow 5 is not performed until a situation occurs in which the inkjet head 21 that should perform ink deposition and the active light irradiation device 53 that should perform light irradiation are not in an opposing positional relationship, and flows 2 to 4 are repeated, and the printing operation is performed sequentially downstream in the printing direction with the 10th scan and the 11th scan.

Then, depending on the configuration of the inkjet printing device 1, when the printing operation is repeated sequentially as described above and the first carriage 31 and the second carriage 51 reach the printing end position, if there is a limit to the movement range of the second carriage 51 due to limitations in the mechanical configuration, a situation may arise in which the second carriage 51 cannot be moved further downstream in the printing direction.

In the example of FIG. 8, if the second carriage 51 cannot be moved further downstream in the printing direction at the point where flows 3 and 4 have been performed in the 28th scan, returning to flow 2 and attempting to perform the 29th scan will result in the first carriage 31 being able to move a first distance downstream in the printing direction, but the second carriage 51 being unable to move a second distance downstream in the printing direction. As a result, a state will arise where none of the inkjet heads 21A to 21D that should be printing in the 29th scan are positioned opposite the active light irradiation device 53.

Therefore, even in such a case, it is effective to carry out the positional relationship adjustment operation of flow 5. Taking the 29th scan of this explanatory example as an example, the first carriage 31 is moved a first distance downstream in the printing direction, and the second carriage 51 is moved a second distance upstream in the printing direction. As a result, in the 29th scan, the inkjet head 21A and the active light irradiation device 53B, the inkjet head 21B and the active light irradiation device 53C, the inkjet head 21C and the active light irradiation device 53D, and the inkjet head 21D and the active light irradiation device 53E are all positioned facing each other.

As described above, in this embodiment, this is performed when the first carriage 31 passes through the printing start position or the printing end position.

In addition, in the 29th scan, the inkjet head 21E has already applied the necessary ink to the outer peripheral surface of the rod-shaped member 3 in a specified printing area from one end to the other end in the axial direction, so there is no need to face the active light irradiation device 53.

As described above, according to the flowchart in FIG. 7, steps 1 to 5 are repeated as appropriate to continue the printing operation, with the 30th and 31st scans being performed, until printing is completed for all print areas. In the example of FIG. 8, the printing operation is completed when the 36th scan is performed.

Then, in accordance with the flowchart, the main curing operation of flow 6 is carried out. The main curing active light irradiation device 35 mounted on the first carriage 31 is operated, and while the first carriage 31 is moved by the first carriage moving means 33, active light stronger than the active light irradiated from the active light irradiation device 53 is irradiated from one end of the outer circumferential surface of the rod-shaped member 3 to the other end, completely curing the applied ink.

Through the above sequence, printing using the inkjet printing device 1 in this embodiment was completed, and printing was performed efficiently and quickly on the outer surface of the rod-shaped member 3.

As an example of application of the above sequence, a printing sequence based on the schematic diagram in Figure 8 will be described in detail for each scan.

The inkjet head 21E mounted on the side closest to the print start position among the inkjet heads 21 mounted on the first carriage 31 is moved to the print start position of the print area of the rod-shaped member 3, and the active light irradiation device 53A, which is the active light irradiation device 53 mounted on the second carriage 51 and is closest to the print start position, is moved to the print start position, so that the inkjet head 21E and the active light irradiation device 53A are positioned facing each other via the rod-shaped member 3 (sandwiched between them).

In this state, ink E (hereinafter, the inks ejected from inkjet heads 21A to 21E are referred to as ink A to ink E, respectively) is ejected from multiple nozzles corresponding to the nozzle length L2 of inkjet head 21E onto the outer peripheral surface of rod-shaped member 3, which is rotated by holding and rotating unit 41, to apply ink E to the outer peripheral surface of rod-shaped member 3, and active light irradiation device 53A is driven to irradiate the outer peripheral surface of rod-shaped member 3 with active light, thereby curing ink E applied to the outer peripheral surface of rod-shaped member 3 (one scan).

Then, the first carriage 31 and the second carriage 51 are moved downstream in the nozzle row direction by a distance corresponding to the nozzle length L2. In this state, ink E is ejected from a plurality of nozzles of the inkjet head 21E corresponding to the nozzle length L2 toward the outer peripheral surface of the rod-shaped member 3 rotated by the holding and rotating unit 41 to apply ink E to the outer peripheral surface of the rod-shaped member 3, and the active light irradiation device 53A is driven to irradiate the outer peripheral surface of the rod-shaped member 3 with active light to cure the ink E applied to the outer peripheral surface of the rod-shaped member 3 (2 scans).

Next, the first carriage 31 is moved downstream in the nozzle row direction by a distance corresponding to the nozzle length L2. Meanwhile, the second carriage 51 is moved upstream in the nozzle row direction on the opposite side to the movement direction of the first carriage 31 by a distance corresponding to the nozzle length L2. As a result, the inkjet head 21E faces the active light irradiation device 53B via the rod-shaped member 3 (sandwiched therebetween), and further the inkjet head 21D faces the active light irradiation device 53A.

In this state, ink E and ink D are ejected from multiple nozzles corresponding to nozzle length L2 of inkjet head 21E and multiple nozzles corresponding to nozzle length L2 of inkjet head 21D, respectively, onto the outer peripheral surface of the rod-shaped member 3 rotated by holding and rotating unit 41, thereby applying ink to the outer peripheral surface of rod-shaped member 3, and active light irradiation device 53A and active light irradiation device 53B are driven to irradiate the outer peripheral surface of rod-shaped member 3 with active light, thereby hardening the ink applied to the outer peripheral surface of rod-shaped member 3 (3 scans).

After this, the same operations as (2nd scan) and (3rd scan) are repeated, and inkjet heads 21C-B are moved in order to the print start position to apply ink to the outer circumferential surface of the rod-shaped member 3 and harden the applied ink (4th scan to 8th scan). Then, the rearmost inkjet head 21A moves to the print start position. As a result, the positional relationship is such that inkjet head 21A faces active light irradiation device 53A, inkjet head 21B faces active light irradiation device 53B, inkjet head 21C faces active light irradiation device 53C, inkjet head 21D faces active light irradiation device 53D, and inkjet head 21E faces active light irradiation device 53E through the rod-shaped member 3 (sandwiched therebetween).

In this state, ink A, ink B, ink C, ink D, and ink E are ejected from multiple nozzles corresponding to nozzle length L2 of inkjet head 21A to multiple nozzles corresponding to nozzle length L2 of inkjet head 21E, respectively, onto the outer peripheral surface of the rod-shaped member 3 rotated by holding and rotating unit 41, thereby applying ink to the outer peripheral surface of rod-shaped member 3, and active light irradiation devices 53A to 53E are driven to irradiate the outer peripheral surface of rod-shaped member 3 with active light, thereby curing the ink applied to the outer peripheral surface of rod-shaped member 3 (9 scans).

Then, the first carriage 31 and the second carriage 51 are moved downstream in the nozzle row direction by a distance corresponding to the nozzle length L2. In this state, ink A, ink B, ink C, ink D, and ink E are ejected from the multiple nozzles corresponding to the nozzle length L2 of the inkjet head 21A to the multiple nozzles corresponding to the nozzle length L2 of the inkjet head 21E, respectively, onto the outer peripheral surface of the rod-shaped member 3 rotated by the holding and rotating unit 41, thereby applying ink to the outer peripheral surface of the rod-shaped member 3, and the active light irradiation devices 53A to 53E are driven to irradiate the outer peripheral surface of the rod-shaped member 3 with active light, thereby curing the ink applied to the outer peripheral surface of the rod-shaped member 3 (10 scans).

After this, the same operation processes as (scan 9) and (scan 10) are repeated until the inkjet head 21E reaches the printing end position, and inks A to E are applied to the printing area of the rod-shaped member 3 and the applied inks are cured (scan 11 to scan 27).

Then, when the inkjet head 21E reaches the printing end position, the inkjet heads 21A-E perform the ink application operation and the active light irradiation devices 53A-E mounted on the second carriage 51 perform the ink curing process (28 scans), and then the first carriage 31 is moved downstream in the nozzle row direction by a distance corresponding to the nozzle length L2. Meanwhile, the second carriage 51 is moved upstream in the nozzle row direction on the opposite side to the moving direction of the first carriage 31 by a distance corresponding to the nozzle length L2. As a result, the inkjet head 21A faces the active light irradiation device 53B, the inkjet head 21B faces the active light irradiation device 53C, the inkjet head 21C faces the active light irradiation device 53D, and the inkjet head 21D faces the active light irradiation device 53E.

In this state, ink A, ink B, ink C, and ink D are ejected from multiple nozzles corresponding to nozzle length L2 of inkjet head 21A to multiple nozzles corresponding to nozzle length L2 of inkjet head 21D, respectively, onto the outer peripheral surface of the rod-shaped member 3 rotated by holding and rotating unit 41, thereby applying ink to the outer peripheral surface of rod-shaped member 3, and active light irradiation devices 53B to 53E are driven to irradiate the outer peripheral surface of rod-shaped member 3 with active light, thereby curing the ink applied to the outer peripheral surface of rod-shaped member 3 (29 scans).

Then, the first carriage 31 and the second carriage 51 are moved downstream in the nozzle row direction by a distance corresponding to the nozzle length L2. In this state, ink A, ink B, ink C, and ink D are ejected from the multiple nozzles corresponding to the nozzle length L2 of inkjet head 21A to the multiple nozzles corresponding to the nozzle length L2 of inkjet head 21D, respectively, onto the outer peripheral surface of the rod-shaped member 3 rotated by the holding and rotating unit 41, thereby applying ink to the outer peripheral surface of the rod-shaped member 3, and the active light irradiation devices 53B to 53E are driven to irradiate the outer peripheral surface of the rod-shaped member 3 with active light, thereby curing the ink applied to the outer peripheral surface of the rod-shaped member 3 (30 scans).

After this, the same operation process as (scan 29) and (scan 30) is repeated, and ink is applied to the outer peripheral surface of the rod-shaped member 3 and the applied ink is cured while the inkjet heads 21D-A are moved in order to the print end position (scans 31-35). Then, the rearmost inkjet head 21A moves to the print end position. This positions the inkjet head 21A facing the active light irradiation device 53E via the rod-shaped member 3 (sandwiched between them).

In this state, ink A is ejected from multiple nozzles corresponding to the nozzle length L2 of the inkjet head 21A onto the outer peripheral surface of the rod-shaped member 3, which is rotated by the holding and rotating unit 41, to apply ink to the outer peripheral surface of the rod-shaped member 3, and the active light irradiation device 53E is driven to irradiate the outer peripheral surface of the rod-shaped member 3 with active light, thereby hardening the ink applied to the outer peripheral surface of the rod-shaped member 3 (35 scans).

In the example of Figure 8, by carrying out all of the above steps, ink can be applied to the outer peripheral surface of the rod-shaped member 3 to form an image. After 35 scans are completed, a full curing operation is carried out as necessary to completely cure the ink and complete the entire printing operation.

1 Inkjet printing device 3 Rod-shaped member 21 Inkjet head 23 Nozzle surface 25 Nozzle configuration part 27 Nozzle 31 First carriage 33 First carriage moving means 34 First carriage up and down moving means 35 Actinic light irradiation device for main curing 36 Height detection means 41 Holding and rotating unit 42 Rotation motor 43 Up and down moving means 44 Pivot 45 Holding and rotating unit moving means 46 Vibration suppression unit 47 First vibration suppression unit moving means 48 Second vibration suppression unit moving means 51 Second carriage 53 Actinic light irradiation device 54 Light irradiation surface 55 Second carriage moving means 57 Irradiation area limiting unit 58 Actinic light 60 Control computer 61 Controller 62 Motor drive driver 63 Linear motor 64 Motor drive driver 65 Linear motor 66 Drive driver 68 Driver 69 Head control board

Claims (12)

1. An inkjet printing apparatus for recording an image by ejecting ink from an inkjet head onto an outer circumferential surface of a rod-shaped member that rotates around a predetermined rotation axis ,
a first carriage carrying a plurality of inkjet heads at first intervals in a first direction along a direction in which the rod-shaped member extends, the inkjet heads recording an image having a predetermined recording width in the first direction ;
a second carriage having a plurality of actinic ray irradiating means mounted at a second interval in the first direction for performing an irradiation process for irradiating an image recorded in the recording width on the outer circumferential surface of the rod-shaped member with actinic ray to cure the ink;
a first carriage moving means for moving the first carriage so as to move the inkjet heads in the first direction by a distance corresponding to the recording width in response to a recording operation for recording an image in the recording width in a print area on the outer circumferential surface of the rotating rod-shaped member ;
a second carriage moving means for moving the second carriage in the first direction or a second direction opposite to the first direction in response to execution of the irradiation process so as to bring the active light ray irradiation means into correspondence with the inkjet head located opposite the printing area;
a control means for adjusting a correspondence relationship between the inkjet head and the actinic ray irradiation means by controlling an operation of the first carriage moving means and the second carriage moving means;
having
The control means
a downstream inkjet head mounted most downstream in the first direction among the plurality of inkjet heads mounted on the first carriage is positioned to face a print start position in the print area, and an upstream active light irradiation means mounted most upstream in the first direction among the plurality of active light irradiation means mounted on the second carriage is positioned to face the print start position so as to correspond to the downstream inkjet head, thereby performing the recording operation by the downstream inkjet head and the irradiation process by the upstream active light irradiation means;
thereafter, when the movement of the first carriage in the first direction in response to the execution of the recording operation causes the inkjet head mounted on the first carriage upstream of the downstream inkjet head in the first direction not to face the print start position, the first carriage is moved in the first direction in response to the execution of the recording operation, and the second carriage is moved in the first direction in response to the execution of the irradiation process, thereby performing the recording operation by the inkjet head positioned to face the print area and the irradiation process by the actinic ray irradiation means corresponding to the inkjet head positioned to face the print area and performing the recording operation, while maintaining the corresponding relationship between the inkjet heads and the actinic ray irradiation means;
On the other hand, when the movement of the first carriage in the first direction in response to the execution of the recording operation causes the inkjet head mounted on the first carriage upstream of the downstream inkjet head in the first direction to be positioned opposite the print start position, the inkjet printing device moves the first carriage in the first direction in response to the execution of the recording operation and moves the second carriage in the second direction in response to the execution of the irradiation process, thereby executing the recording operation by a plurality of the inkjet heads positioned opposite the printing area and the irradiation process by a plurality of the actinic ray irradiation means corresponding to the plurality of the inkjet heads positioned opposite the printing area and performing the recording operation . 1. An inkjet printing apparatus for recording an image by ejecting ink from an inkjet head onto an outer circumferential surface of a rod-shaped member that rotates around a predetermined rotation axis ,
a first carriage carrying a plurality of inkjet heads at first intervals in a first direction along a direction in which the rod-shaped member extends, the inkjet heads recording an image having a predetermined recording width in the first direction ;
a second carriage having a plurality of actinic ray irradiating means mounted at a second interval in the first direction, the actinic ray irradiating means performing an irradiation process for irradiating an image recorded in the recording width on the outer circumferential surface of the rod-shaped member with actinic ray to cure the ink;
a first carriage moving means for moving the first carriage so as to move the inkjet heads in the first direction by a distance corresponding to the recording width in response to a recording operation for recording an image in the recording width in a print area on the outer circumferential surface of the rotating rod-shaped member ;
a second carriage moving means for moving the second carriage in the first direction or a second direction opposite to the first direction in response to execution of the irradiation process so as to bring the active light ray irradiation means into correspondence with the inkjet head located opposite to the printing area;
a control means for adjusting a correspondence relationship between the inkjet head and the actinic ray irradiation means by controlling an operation of the first carriage moving means and the second carriage moving means;
having
The control means
a downstream inkjet head mounted most downstream in the first direction among the plurality of inkjet heads mounted on the first carriage is positioned to face a print end position in the print area, and a downstream active light irradiation means mounted most downstream in the first direction among the plurality of active light irradiation means mounted on the second carriage is positioned to face the print end position so as to correspond to the downstream inkjet head, thereby performing the recording operation by the plurality of inkjet heads mounted on the first carriage and the irradiation process by the plurality of active light irradiation means mounted on the second carriage;
thereafter, when the movement of the first carriage in the first direction in response to the execution of the recording operation causes the inkjet head mounted on the first carriage upstream of the downstream inkjet head in the first direction to not be positioned opposite the print end position, the first carriage is moved in the first direction in response to the execution of the recording operation, and the second carriage is moved in the second direction in response to the execution of the irradiation process, thereby performing the recording operation by the inkjet head positioned opposite the print area and the irradiation process by the actinic ray irradiation means corresponding to the inkjet head positioned opposite the print area and performing the recording operation, in a state in which a corresponding relationship between the inkjet heads and the actinic ray irradiation means has been changed;
On the other hand, when the movement of the first carriage in the first direction in response to the execution of the recording operation causes the inkjet head mounted on the first carriage upstream of the downstream inkjet head in the first direction to be positioned opposite the print end position, the first carriage is moved in the first direction in response to the execution of the recording operation, and the second carriage is moved in the first direction in response to the execution of the irradiation process, thereby performing the recording operation by the inkjet head positioned opposite the print area and the irradiation process by the actinic ray irradiation means corresponding to the inkjet head positioned opposite the print area and performing the recording operation, while maintaining a corresponding relationship between the inkjet heads and the actinic ray irradiation means. the inkjet head has a nozzle surface in which a plurality of nozzles for ejecting ink are arranged in a predetermined direction, the nozzle surface having a nozzle configuration portion in which the plurality of nozzles are arranged in the predetermined direction at predetermined nozzle intervals;
3. The inkjet printing apparatus according to claim 1, wherein the first interval is substantially equal to a length that is an integer multiple of the nozzle interval. the recording operation is a process for recording an area on an outer circumferential surface of the rod-shaped member, the area corresponding to a length of the recording area in the first direction and the predetermined amount of rotation, using a recording area corresponding to some or all of the plurality of nozzles of the nozzle configuration portion during a rotation operation of the rod-shaped member by a predetermined amount of rotation;
4. The inkjet printing apparatus according to claim 3 , wherein the first interval is approximately equal to an integer multiple of a length of the recording area in the first direction. 5. The inkjet printing apparatus according to claim 3 , wherein the first interval is approximately equal to a length that is an integer multiple of a length of the nozzle component in the first direction. 5. The inkjet printing apparatus according to claim 4 , wherein a distance by which said first carriage is moved in said first direction by said first carriage moving means is approximately equal to a length of said recording area in said first direction . 7. The inkjet printing device according to claim 3, wherein, among the plurality of inkjet heads mounted on the first carriage, execution of the recording operation is started sequentially from an inkjet head that has reached a position where the rod-shaped member faces the nozzle surface by the first carriage movement operation. 8. An inkjet printing device as claimed in claim 3, further comprising a function of changing an angle at which the rod-shaped member is held in accordance with an angle of gradient of the outer peripheral surface of the rod-shaped member relative to a central axis of the rod-shaped member, so that the nozzle face and the outer peripheral surface of the rod-shaped member are approximately parallel to each other . 9. An inkjet printing apparatus as described in any one of claims 1 to 8, further comprising a support member for restricting movement of the rod-shaped member in a direction substantially perpendicular to the first direction , and the support member has a mechanism for moving the rod-shaped member in a direction substantially perpendicular to an axial direction of the rod -shaped member in accordance with a diameter of the rod-shaped member. 10. The inkjet printing device according to claim 1 , wherein the second carriage has a function of changing a distance between the outer circumferential surface of the rod-shaped member and the actinic light ray application means in accordance with an angle of gradient of the outer circumferential surface of the rod-shaped member with respect to a central axis of the rod - shaped member. 11. The inkjet printing apparatus according to claim 1 , wherein the actinic ray irradiating means has an irradiation area limiting unit for limiting an area irradiated with the actinic ray. 12. The inkjet printing apparatus according to claim 1, wherein the first carriage further comprises an actinic ray irradiation means .

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