JP5439855B2 - Ink ejecting apparatus and ink ejecting method - Google Patents

Description

  The present invention relates to an ink ejecting apparatus and an ink ejecting method.

  A head for ejecting ultraviolet curable ink that is cured by receiving ultraviolet rays, and a semi-curing irradiation section for irradiating the ultraviolet curable ink with ultraviolet rays so that the ultraviolet curable ink is in a semi-cured state (head and semi-cured) An ink ejecting apparatus including a set of irradiation units is called an ink image forming unit is already well known. Some of the ink ejecting apparatuses include a plurality of ink image forming units (for example, for each ink color). For example, in such an ink ejecting apparatus, a plurality of color ink images are superimposed on a medium to form a color image.

JP 2007-230232 A

In the ink ejecting apparatus having the above-described configuration, there may be a problem that the degree of the ink semi-cured state is not uniform among the ink image forming units (for example, between ink colors). Therefore, a method for making the degree of the semi-cured state uniform is required.
This invention is made | formed in view of this subject, The place made into the objective is aiming at equalization of the grade of a semi-hardened state.

The main present invention includes a head for ejecting ultraviolet curable ink that is cured by receiving ultraviolet rays;
An intermediate transfer member for transferring the ultraviolet curable ink to the transfer target after receiving the ultraviolet curable ink ejected by the head;
A plurality of intermediate transfer body units having a semi-curing irradiation section for irradiating the ultraviolet curable ink on the intermediate transfer body with ultraviolet rays to make the ultraviolet curable ink semi-cured,
The head performs a jetting operation of jetting the ultraviolet curable ink a plurality of times,
The intermediate transfer member is
An attachment surface to which the ultraviolet curable ink is attached; and
Both the ultraviolet curable ink ejected from the head in one ejection operation of the plurality of ejection operations and the ultraviolet curable ink ejected from the head in the ejection operation subsequent to the one ejection operation. However, by pressing the adhering surface adhering across the gap formed between the two against the transfer target, the both are transferred to the transfer target while crushing the gap so that the gap is filled. And
The intermediate transfer body is a rotatable rotator provided with a peripheral surface as the attachment surface, and the peripheral surface of the rotating rotator is pressed against a medium as the transfer target, Transfer both to the medium,
A transport unit that transports the medium so that the medium passes through a transfer position where the intermediate transfer member transfers both of the media to the medium;
The linear velocity of the rotating body at the transfer position is different from the moving speed of the medium when passing through the transfer position,
An ink ejecting apparatus, wherein a linear velocity of the rotating body of one of the plurality of intermediate transfer body units is different from a linear velocity of the rotating body of another intermediate transfer body unit. is there.

1 is a block diagram illustrating a configuration of a printer. 2 is a diagram illustrating main components of the printer 1. FIG. FIG. 4 is a diagram showing the arrangement of nozzles Nz on the nozzle surface 22. 2 is a schematic plan view of an ink image forming unit 20. FIG. It is a figure which shows the flow of printing operation. 3 is a schematic diagram showing UV ink droplets attached to a peripheral surface 33 of an intermediate transfer body 31. FIG. 3 is a diagram illustrating a state in which UV ink droplets on a peripheral surface 33 of an intermediate transfer body 31 are transferred to a medium S. FIG. FIG. 2 is a diagram illustrating main components of a printer 1 according to a comparative example. It is explanatory drawing about the bleeding of UV ink droplets. 4 is a schematic diagram showing UV ink transferred to a medium S. FIG. FIG. 10 is a diagram when the magnitude of the linear velocity v1 of the intermediate transfer body 31 at the transfer position is smaller than the magnitude of the moving speed v2 of the medium S when passing through the transfer position. It is a figure which shows the main components of the printer 1 which concerns on other embodiment.

  At least the following will be made clear by the description of the present specification and the accompanying drawings.

A head for ejecting ultraviolet curable ink which is cured by receiving ultraviolet rays;
An intermediate transfer member for transferring the ultraviolet curable ink to the transfer target after receiving the ultraviolet curable ink ejected by the head;
A plurality of intermediate transfer body units having a semi-curing irradiation section for irradiating the ultraviolet curable ink on the intermediate transfer body with ultraviolet rays so as to make the ultraviolet curable ink semi-cured. Ink ejection device.
According to the ink ejecting apparatus, the degree of the semi-cured state is made uniform.

The head performs a jetting operation of jetting the ultraviolet curable ink a plurality of times,
The intermediate transfer member is
An attachment surface to which the ultraviolet curable ink is attached; and
Both the ultraviolet curable ink ejected from the head in one ejection operation of the plurality of ejection operations and the ultraviolet curable ink ejected from the head in the ejection operation subsequent to the one ejection operation. However, by pressing the adhering surface adhering across the gap formed between the two against the transfer target, the both are transferred to the transfer target while crushing the gap so that the gap is filled. It is good to do.
In such a case, the blurring between the inks is suppressed, and image quality deterioration is suppressed.

The intermediate transfer member is a rotatable rotating member having a peripheral surface as the attachment surface, and the peripheral surface of the rotating rotating member is pressed against a medium as the transfer target. , Transfer both to the medium,
A transport unit that transports the medium so that the medium passes through a transfer position where the intermediate transfer member transfers both of the media to the medium;
The linear velocity of the rotating body at the transfer position is different from the moving speed of the medium when passing through the transfer position,
The linear velocity of the rotating member of one intermediate transfer member unit among the plurality of intermediate transfer member units may be different from the linear velocity of the rotating member of another intermediate transfer member unit.
In such a case, it is possible to expand image variations (to obtain images having various types of image characteristics).

Next, each head provided in the plurality of intermediate transfer body units ejects ultraviolet curable ink that is cured by receiving ultraviolet rays, and
Each intermediate transfer member provided in the plurality of intermediate transfer member units receives the ultraviolet curable ink ejected by each head;
Each of the semi-curing irradiation units provided in the plurality of intermediate transfer body units irradiates the ultraviolet curable ink on each of the intermediate transfer bodies with ultraviolet rays so that the ultraviolet curable ink is in a semi-curing state. When,
Each of the intermediate transfer members transfers the ultraviolet curable ink to a transfer target;
An ink ejecting method comprising:
According to such an ink ejection method, the degree of the semi-cured state is made uniform.

=== Outline of Ink Ejecting Device of the Present Embodiment ===
In the present embodiment, an ink jet printer (hereinafter, printer 1) as an example of an ink ejecting apparatus will be described. The printer 1 prints an image on a medium S such as paper, cloth, or film sheet using ink (ink is a concept including both water-based ink and oil-based ink. In the present embodiment, water-based ink). Printing device. In particular, in this embodiment, ultraviolet curable ink (hereinafter, UV ink) that is cured by receiving ultraviolet rays is used. UV ink is an ink prepared by adding an auxiliary agent such as an antifoaming agent to a mixture of a vehicle containing a UV curable resin, a photopolymerization initiator, and a pigment. It hardens when a polymerization reaction occurs. Note that the printer 1 of this embodiment prints a color image using KCMY four-color UV ink.

<< Configuration of Printer 1 >>
As shown in FIGS. 1 and 2, the printer 1 includes a controller 10, a plurality of (four in the present embodiment) intermediate transfer body units 18, a transport unit 40 as an example of a transport unit, and a fixing unit. Unit 50. FIG. 1 is a block diagram illustrating a configuration of the printer 1. FIG. 2 is a diagram illustrating main components of the printer 1, and the vertical direction is indicated by an arrow in the drawing.

  The controller 10 is a control device built in the printer 1, receives print data transmitted from the host computer 110 via the interface 11, and is executed by the CPU 12 via the unit control circuit 14 in accordance with a program stored in the memory 13. The above units (intermediate transfer member unit 18, transport unit 40, fixing unit 50) are controlled. As a result, an image corresponding to the print data is printed on the medium S. The state in the printer 1 is monitored by the detector group 60, and the controller 10 controls each unit based on the detection result.

  The intermediate transfer body unit 18 includes an ink image forming unit 20 having a head 21 and a semi-curing irradiation unit 23, and an intermediate transfer body 31. A total of four intermediate transfer units 18 are provided for each color of UV ink, that is, for each of black (K), cyan (C), magenta (M), and yellow (Y) (four intermediate transfer units). Each of the body units is referred to as a black intermediate transfer body unit 18K, a cyan intermediate transfer body unit 18C, a magenta intermediate transfer body unit 18M, and a yellow intermediate transfer body unit 18Y). Since the four intermediate transfer body units 18 have the same configuration, the black intermediate transfer body unit 18K will be described below.

  The ink image forming unit 20 provided in the black intermediate transfer body unit 18K is an apparatus for forming an ink image on the peripheral surface 33 of the intermediate transfer body 31 that is a drum-like rotating body, as shown in FIG. Are provided along the peripheral surface 33. The ink image forming unit 20 includes a head 21 and a semi-curing irradiation unit 23.

  The head 21 has a plurality of nozzles Nz formed on a surface (hereinafter referred to as a nozzle surface 22) on the side facing the peripheral surface 33 of the intermediate transfer body 31. As shown in FIG. 3, the plurality of nozzles Nz are arranged at a constant nozzle pitch (180 dpi (1/180 inch) in the present embodiment) along the axial direction of the intermediate transfer member 31 on the nozzle surface 22 of the head 21. Lined up nozzle rows. FIG. 3 is a diagram showing the arrangement of the nozzles Nz on the nozzle surface 22.

  The head 21 performs an ejection operation for ejecting UV ink from each nozzle Nz in a state where the nozzle surface 22 faces the peripheral surface 33 of the intermediate transfer body 31. Thereby, droplet-like UV ink (UV ink droplets) adheres (lands) to the peripheral surface 33 of the intermediate transfer member 31 (in other words, the intermediate transfer member 31 receives the UV ink). When the UV ink droplets adhere to the peripheral surface 33 of the intermediate transfer member 31, the UV ink droplet forms a substantially hemispherical shape on the peripheral surface 33. In the present embodiment, as shown in FIG. 4, a plurality of heads 21 are arranged in a staggered pattern along the axial direction of the intermediate transfer member 31. The nozzles Nz face each other from one end to the other end of the peripheral surface 33 in the axial direction of the intermediate transfer member 31. As a result, in one ejection operation, UV ink is ejected toward the range of the peripheral surface 33 from one end to the other end in the axial direction, and a plurality of UVs arranged in a row from the one end to the other end. Ink droplets (hereinafter also referred to as UV ink droplet groups) adhere to the peripheral surface 33 at a time. FIG. 4 is a schematic plan view of the ink image forming unit 20.

  The semi-curing irradiation unit 23 is for irradiating the UV ink on the intermediate transfer body 31 with ultraviolet rays so that the UV ink is in a semi-curing state. The semi-curing irradiation unit 23 includes a light source 24 that emits ultraviolet rays, such as a light emitting element (LED), and is located downstream of the head 21 in the rotation direction of the intermediate transfer body 31. Then, the semi-curing irradiation unit 23 irradiates the UV ink droplets on the peripheral surface 33 with the ultraviolet rays emitted from the light source 24. The UV ink droplets start to be gradually cured by receiving the ultraviolet rays when passing directly under the semi-curing irradiation portion 23 as the intermediate transfer member 31 rotates.

  The irradiation intensity when the semi-irradiation device 26 irradiates ultraviolet rays is set so weak that the curing of the UV ink that has received the ultraviolet rays is contained in the vicinity of the surface thereof. For this reason, the UV ink droplets that have received the ultraviolet rays from the semi-curing irradiation part 23 are in a semi-cured state (the surface is cured while the inside remains uncured and is not completely cured). It becomes. The UV ink droplet at the time when it is in a semi-cured state upon receiving the ultraviolet light from the semi-cured irradiation part 23 still has a substantially hemispherical shape.

  The ink image forming unit 20 configured as described above repeats the UV ink ejection operation by the head 21 and the ultraviolet irradiation operation by the semi-curing irradiation unit 23, thereby forming ink composed of UV ink droplets in a semi-curing state. An image is formed on the peripheral surface 33 of the intermediate transfer member 31.

  The intermediate transfer member 31 receives the UV ink ejected by the head 21 and then transfers the UV ink (in other words, an ink image formed of UV ink droplets) to a medium S as an example of a transfer target. As described above, the intermediate transfer member 31 includes the peripheral surface 33 as an attachment surface to which the UV ink is attached, and is supported rotatably. And while the printer 1 is performing printing operation, it always rotates in the rotation direction (direction shown by the arrow in FIG. 2).

  In the present embodiment, the intermediate transfer member 31 transfers an ink image to a medium in cooperation with the pressing roller 32. The pressing roller 32 is disposed below the intermediate transfer member 31 and presses the medium S toward the peripheral surface 33 of the intermediate transfer member 31. As a result, the peripheral surface 33 is pressed against the medium S. More specifically, the intermediate transfer member 31 cooperates with the pressing roller 32 to sandwich the medium S conveyed between the intermediate transfer member 31 and the pressing roller 32. A pressing force from the pressing roller 32 acts on a portion of the medium S sandwiched between the intermediate transfer member 31 and the pressing roller 32. At this time, UV ink droplets attached to a portion of the peripheral surface 33 of the intermediate transfer body 31 that contacts the medium S (that is, a portion that sandwiches the medium S with the pressing roller 32) are transferred to the medium S. Is done.

  As described above, the intermediate transfer member 31 of the present embodiment transfers the UV ink droplets on the peripheral surface 33 to the medium S by pressing the peripheral surface 33 against the medium S in cooperation with the pressing roller 32. . In the present embodiment, as described above, before the UV ink droplet is transferred to the medium S, the UV ink droplet is subjected to ultraviolet rays from the semi-curing irradiation unit 23 and is in a semi-curing state. Therefore, the intermediate transfer member 31 transfers the UV ink droplets on the peripheral surface 33 in a semi-cured state to the medium S. In addition, each of the intermediate transfer members 31 of the four intermediate transfer member units 18K, 18C, 18M, and 18Y performs the above-described transfer operation. By the transfer operation, four color ink images are superimposed on the medium S to obtain a color. An image will be formed.

  The transport unit 40 rotates while pinching the medium S so that the medium S fed into the printer 1 passes through the transfer position by a pair of transport rollers 41 (see FIG. 2) that transport the medium S. The medium S is conveyed, and the medium S that has passed through the transfer position is further conveyed toward the fixing unit 50. Here, the transfer position is a position in the conveyance path of the medium S where the intermediate transfer body 31 transfers the UV ink droplets to the medium S. Specifically, the medium S includes the intermediate transfer body 31 and the pressing roller 32. It is a position that is sandwiched between them.

  In the present embodiment, the medium S is transported such that the direction in which the medium S passes through the transfer position is the same as the direction in which the intermediate transfer body 31 rotates at the transfer position. In other words, the intermediate transfer member 31 of the present embodiment rotates at the transfer position in the same direction as the direction in which the medium S passes when passing through the transfer position.

  The fixing unit 50 includes a light source 51 such as a metal halide lamp, and irradiates UV ink (hereinafter also referred to as dots) transferred to the medium S with ultraviolet rays emitted from the light source 51, thereby transferring the dots. The image is fixed on the medium S. The irradiation intensity when the fixing unit 50 irradiates ultraviolet rays is stronger than the irradiation intensity when the semi-curing irradiation unit 23 irradiates ultraviolet rays, and the UV ink (in other words, dots) that has been semi-cured in advance is fixed. When the ultraviolet rays from the unit 50 are received, the main cured state (completely cured to the inside) is obtained.

  In addition, as the ultraviolet light sources 24 and 51 provided in each of the semi-curing irradiation unit 23 and the fixing unit 50, a xenon lamp, a carbon arc lamp, a chemical lamp, and a low-pressure mercury lamp in addition to the above-described metal halide lamp and light emitting element (LED) Also, a high-pressure mercury lamp can be used.

<< Operation Example of Printer 1 >>
Next, a printing operation as an operation example of the printer 1 having the above configuration will be described.
As shown in FIG. 5, the printing operation starts when the controller 10 receives print data from the host computer 110 (S001). FIG. 5 is a diagram showing the flow of the printing operation. Thereafter, the controller 10 analyzes the contents of various commands included in the print data and controls each unit. Thereby, first, the intermediate transfer member 31 rotates and the light sources 24 and 51 of the semi-curing irradiation unit 23 and the fixing unit 50 are turned on (S002). In such a state, the medium S is fed into the printer 1.

  While the intermediate transfer member 31 is rotating, each of the plurality of heads 21 arranged in a staggered manner along the axial direction of the intermediate transfer member 31 has a nozzle surface 22 facing the peripheral surface 33 of the intermediate transfer member 31. In this state, the ejection operation for ejecting the UV ink toward the peripheral surface 33 is intermittently performed a plurality of times (S003). As a result, the above-described UV ink droplet group adheres to the circumferential surface 33 at regular intervals along the circumferential direction of the circumferential surface 33 (that is, the rotation direction of the intermediate transfer member 31). That is, an ink image composed of UV ink droplet groups is gradually formed on the peripheral surface 33.

  Here, the interval between the UV ink droplet groups is the interval between the UV ink droplets in the circumferential direction (the distance between the centers of the UV ink droplets). Further, the diameter of the UV ink droplet is smaller than the interval between the UV ink droplets. Therefore, as shown in FIG. 6, a gap 34 is formed between the UV ink droplets adjacent in the circumferential direction. FIG. 6 is a schematic diagram showing UV ink droplets attached to the peripheral surface 33 of the intermediate transfer member 31.

  As described above, when the UV ink droplets ejected from the head 21 are arranged and adhered to the peripheral surface 33 of the intermediate transfer member 31 along the circumferential direction of the peripheral surface 33, a gap is formed between the UV ink droplets. The UV ink droplets are attached to the peripheral surface 33 so that 34 is formed. In other words, the UV ink droplets ejected from the head 21 in one ejection operation among a plurality of ejection operations (for example, the nth UV ink droplet in FIG. 6), and the next of the one ejection operation. Both of the UV ink droplets ejected from the head 21 in the ejection operation (n + 1th UV ink droplet in FIG. 6) are attached to the peripheral surface 33 with a gap 34 formed therebetween. Become.

  Note that the size of the gap 34 in the circumferential direction depends on parameters such as the interval of the ejection operation (that is, the ejection interval of the UV ink) and the peripheral speed of the intermediate transfer member 31, and the unit control circuit 14 can be controlled by the controller 10.

  The UV ink droplets adhering to the peripheral surface 33 pass immediately below the semi-curing irradiation portion 23 in the rotation direction of the intermediate transfer body 31 as the intermediate transfer body 31 rotates. In such a position, the UV ink droplet receives the ultraviolet rays from the semi-curing irradiation unit 23 and is in a semi-curing state (S004). Thereafter, the UV ink droplets on the peripheral surface 33 in a semi-cured state move to the downstream side in the rotation direction due to the further rotation of the intermediate transfer member 31, and eventually the intermediate transfer member 31 and the pressing roller 32. Come in between. On the other hand, when transferring the UV ink droplet on the peripheral surface 33 to the medium S, the transport unit 40 transports the medium S toward the transfer position. That is, the transport unit 40 transports the medium S so that the medium S passes through the transfer position.

  Then, the medium S moves while being sandwiched between the intermediate transfer member 31 and the pressing roller 32. At this time, the intermediate transfer member 31 presses the circumferential surface 33 against the medium S, and transfers the UV ink droplets on the circumferential surface 33 in a semi-cured state to the medium S (S005). When the peripheral surface 33 is pressed against the medium S, the intermediate transfer member 31 of the present embodiment transfers the UV ink droplets on the peripheral surface 33 that has become semi-cured to the medium S while crushing. As a result, as shown in FIG. 7, UV ink droplets that have been in the shape of a substantially hemisphere so far extend along the circumferential direction of the peripheral surface 33 (in other words, the rotational direction of the intermediate transfer member 31) and are flat. Transforms into As a result, the gap 34 formed between the UV ink droplets is filled by the deformation of the UV ink droplets. FIG. 7 is a diagram illustrating a state in which the UV ink droplets on the peripheral surface 33 of the intermediate transfer body 31 are transferred to the medium S.

  As described above, in the present embodiment, both the UV ink droplet ejected in one ejection operation and the UV ink droplet ejected in the next ejection operation of the one ejection operation are on the peripheral surface 33. After receiving the ultraviolet rays from the semi-curing irradiation unit 23 and becoming a semi-cured state, the intermediate transfer member 31 presses the circumferential surface 33 to which both of the semi-cured states are attached to the medium S. Then, the intermediate transfer member 31 transfers the both onto the medium S while crushing both so that the gap 34 is filled.

  Further, in the present embodiment, the linear velocity of the intermediate transfer member 31 at the transfer position (that is, the peripheral speed of the intermediate transfer member 31 and indicated by the symbol v1 in FIG. 7) The moving speed of the medium S (that is, the transport speed, indicated by the symbol v2 in FIG. 7) is different from each other. More specifically, the intermediate transfer member 31 rotates at the transfer position in the same direction as the medium S moves when passing through the transfer position, and the magnitude of the linear velocity v1 is the moving velocity v2. It is larger than the size of. As a result, deformation of the UV ink droplets is promoted, and when the UV ink droplets on the peripheral surface 33 of the intermediate transfer body 31 are transferred to the medium S, the gap 34 is more easily filled.

  When each of the intermediate transfer bodies 31 of the four intermediate transfer body units 18K, 18C, 18M, and 18Y performs the transfer operation described above, four color ink images are superimposed on the medium S by the transfer operation.

  Thereafter, the superimposed ink image moves to the fixing unit 50 by the conveyance of the medium S by the conveyance unit 40. Then, when the superimposed ink image, that is, the dot receives ultraviolet rays from the fixing unit 50, the dot transits from the semi-cured state to the fully cured state. As a result, the ink image (transfer image) composed of dots is fixed on the medium S as a final image (S006).

  The medium S on which the image is printed by the above steps is discharged out of the printer 1 by a paper discharge mechanism (not shown) (S007). Since the image printed by the above procedure is composed of a plurality of dots arranged with the gap 34 filled, it is an image printed at a desired print density. This will be described in detail in the next section.

=== Effectiveness of Printer 1 of this Embodiment ===
As described above, the printer 1 of this embodiment includes the head 21 for ejecting UV ink and the intermediate transfer for transferring the UV ink to the medium S after receiving the UV ink ejected by the head 21. A plurality of intermediate transfer body units 18 having a body 31 and a semi-curing irradiation section 23 for irradiating the UV ink on the intermediate transfer body 31 with ultraviolet rays to make the UV ink semi-cured. . This makes it possible to achieve a uniform degree of semi-cured state.

  The above will be described with reference to FIGS. 2 and 8 while comparing the printer 1 according to the present embodiment and the printer 1 according to the comparative example. FIG. 8 is a diagram corresponding to FIG. 2 and is a diagram illustrating main components of the printer 1 according to the comparative example. The printer 1 according to the comparative example includes a head 21 for ejecting UV ink and a semi-curing irradiation unit 23 for making the UV ink semi-cured, and a set of the head 21 and the semi-curing irradiation unit 23 (i.e. The printer 1 according to the present embodiment is provided with a plurality of (four for each color) ink image forming units 120), and a point that four color ink images are superimposed on the medium S to form a color image. It is the same. However, the printer 1 according to the comparative example is not provided with an intermediate transfer member, the head 21 ejects UV ink to the medium S (not the intermediate transfer member), and the semi-curing irradiation unit 23 (in the intermediate transfer member). (None) The UV ink on the medium S is irradiated with ultraviolet rays. Therefore, the problem of non-uniformity of the degree of semi-cured state (how much semi-cured) described below arises. That is, as is apparent from FIG. 8, the UV ink (that is, yellow ink) ejected onto the medium S by the head 21 of the yellow ink image forming unit 120Y is only emitted from the semi-curing irradiation unit 23 of the yellow ink image forming unit 120Y. While being irradiated, the UV ink (that is, magenta ink) ejected onto the medium S by the head 21 of the magenta ink image forming unit 120M is not only the semi-cured irradiation portion 23 of the magenta ink image forming unit 120M, Irradiation is also performed by the semi-curing irradiation unit 23 of the yellow ink image forming unit 120Y. Further, UV ink (that is, cyan ink) ejected onto the medium S by the head 21 of the cyan ink image forming unit 120C is half of the cyan ink image forming unit 120C, the magenta ink image forming unit 120M, and the yellow ink image forming unit 120Y. UV ink (that is, black ink) irradiated by the curing irradiation unit 23 and ejected onto the medium S by the head 21 of the black ink image forming unit 120K is the black ink image forming unit 120K, the cyan ink image forming unit 120C, and the magenta ink. Irradiated by the semi-curing irradiation unit 23 of the image forming unit 120M and the yellow ink image forming unit 120Y. Therefore, the irradiation energies received by the inks of the respective colors from the semi-curing irradiation unit 23 are greatly different from each other, and the degree of the semi-curing state is not uniform among the ink image forming units 120 (between ink colors).

  In contrast, in the present embodiment, a head 21 for ejecting UV ink and an intermediate transfer body 31 for transferring the UV ink to the medium S after receiving the UV ink ejected by the head 21. And a plurality of intermediate transfer body units 18 for irradiating the UV ink on the intermediate transfer body 31 with ultraviolet rays to make the UV ink semi-cured. As is clear from FIG. 2, the UV ink (that is, black ink) ejected to the intermediate transfer body 31 by the head 21 of the black intermediate transfer body unit 18K is the semi-curing irradiation section 23 of the black intermediate transfer body unit 18K. UV ink (that is, cyan ink) that is irradiated only by the head and is jetted onto the intermediate transfer member 31 by the head 21 of the cyan intermediate transfer member unit 18C. The UV ink (that is, magenta ink) that is irradiated only by the semi-curing irradiation unit 23 of the cyan intermediate transfer body unit 18C and jetted onto the intermediate transfer body 31 by the head 21 of the magenta intermediate transfer body unit 18M is the magenta intermediate transfer. The UV ink (that is, the yellow ink) that is irradiated only by the semi-curing irradiation unit 23 of the body unit 18M and is jetted onto the intermediate transfer body 31 by the head 21 of the yellow intermediate transfer body unit 18Y is transferred to the yellow intermediate transfer body unit 18Y. Irradiation is performed only by the semi-curing irradiation unit 23. For this reason, the degree of the semi-cured state is made uniform between the ink image forming units 120 (between ink colors).

  Further, in the printer 1 of the present embodiment, the head 21 performs the ejection operation for ejecting the UV ink a plurality of times, and the intermediate transfer body 31 is ejected from the head 21 in one ejection operation of the plurality of ejection operations. The peripheral surface to which both the UV ink droplets and the UV ink droplets ejected from the head 21 in the ejection operation subsequent to the one ejection operation adhere with a gap 34 formed therebetween. By pressing 33 against the medium S, the both are transferred to the medium S while being crushed so that the gap 34 is filled. Thus, it is possible to suppress the blurring between the UV inks, thereby suppressing the image quality deterioration of the image.

  More specifically, when printing an image with a desired print density, when the UV ink droplets ejected from the head 21 in each ejection operation are attached to the peripheral surface 33 of the intermediate transfer member 31, the UV ink droplets You may close the interval. That is, the UV ink droplet ejected in one ejection operation and the UV ink droplet ejected in the next ejection operation of the one ejection operation are attached to the peripheral surface 33 in a state of being separated from each other. The interval between the UV ink droplets is increased, and there is a possibility that the density when the image is actually printed does not become a desired printing density. For this reason, the UV ink droplets are attached to the peripheral surface 33 while the intervals between the UV ink droplets are reduced as described above.

  However, if the interval between the UV ink droplets is reduced, the UV ink droplets tend to ooze as shown in FIG. FIG. 9 is an explanatory diagram of the bleeding between UV ink droplets. Such bleeding between the UV ink droplets causes deterioration in image quality. In particular, when UV ink droplets having different colors ooze during color printing, image quality deterioration becomes more noticeable due to color mixing.

  Therefore, in this embodiment, as described above, both the UV ink droplets ejected in one ejection operation and the UV ink droplets ejected in the next ejection operation of the one ejection operation are both concerned. A gap 34 is provided between the peripheral surface 33 and the peripheral surface 33 (see FIG. 7). That is, since the UV ink droplets at the stage of adhering to the peripheral surface 33 are separated from each other, the oozing of the UV ink droplets on the peripheral surface 33 is suppressed.

  In this embodiment, thereafter, the UV ink droplet on the peripheral surface 33 is irradiated with ultraviolet rays to make the UV ink droplet semi-cured. Since the UV ink droplets in a semi-cured state are difficult to bleed, even if the UV ink drips come close to each other thereafter, the oozing between the UV ink droplets is suppressed. In this state, the UV ink droplet is transferred to the medium S while being crushed so that the gap 34 is filled. As a result, in the medium S to which the UV ink is transferred, the gap 34 is filled as shown in FIG. 10, and the density at the time of actually printing an image also becomes a desired printing density. FIG. 10 is a schematic diagram showing the UV ink transferred to the medium S. As shown in FIG.

  As described above, according to the present embodiment, it is possible to suppress the blurring between the UV inks while ensuring the printing density, thereby suppressing the deterioration of the image quality of the image.

  In this embodiment, the linear velocity v1 of the intermediate transfer body 31 at the transfer position and the moving velocity v2 of the medium S when passing through the transfer position are different from each other. In particular, in the present embodiment, the linear velocity v1 is greater than the moving velocity v2. As described above, if there is a speed difference between the two speeds v1 and v2, the UV ink droplet on the peripheral surface 33 is dragged to the intermediate transfer body 31 at the time of transfer and is urged to be deformed. Further, when the relationship between the two velocities v1 and v2 is the above relationship, the interval d between the UV inks transferred to the medium S is the interval between the UV ink droplets on the peripheral surface 33 of the intermediate transfer body 31. shorter than 1 (see FIG. 7). As a result, when the UV ink droplet on the peripheral surface 33 is transferred to the medium S, the gap 34 is easily filled.

  However, it is not limited to the case where the magnitude of the linear velocity v1 is larger than the magnitude of the moving speed v2, and the magnitude of the linear velocity v1 may be smaller than the magnitude of the moving speed v2. . In this case, as shown in FIG. 11, although the interval d between the UV inks transferred to the medium S is longer than the interval l between the UV ink droplets on the peripheral surface 33 of the intermediate transfer member 31, the above 2 Since there is a speed difference between the two speeds v1 and v2, it is possible to promote deformation of the UV ink droplets. FIG. 11 is a diagram in the case where the magnitude of the linear velocity v1 of the intermediate transfer body 31 at the transfer position is smaller than the magnitude of the moving speed v2 of the medium S when passing through the transfer position, and corresponds to FIG. It is.

  As described above, as long as the magnitude of the linear velocity v1 and the magnitude of the moving velocity v2 are different, the magnitude relationship between the two velocities v1 and v2 does not matter, but the gap 34 between the UV ink droplets is transferred. It is desirable that the magnitude of the linear velocity v1 is larger than the magnitude of the moving velocity v2 in that it is sometimes filled efficiently. On the other hand, in order to increase the printing speed by increasing the moving speed v2 of the medium S, the moving speed v2 is larger than the linear speed v1 (the linear speed v1 is larger than the moving speed). It is preferable to be smaller than the speed v2.

=== Other Embodiments ===
The ink ejecting apparatus and the like according to the present invention have been described above based on the above embodiment. However, the above embodiment of the present invention is for facilitating understanding of the present invention and limits the present invention. is not. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes the equivalents thereof.

  In the above embodiment, each of the plurality of heads 21 arranged in a staggered pattern along the axial direction of the intermediate transfer member 31 ejects UV ink, so that the UVs are arranged in a line along the axial direction. Ink droplets (UV ink droplet group) were allowed to adhere to the peripheral surface 33 of the intermediate transfer member 31. However, the present invention is not limited to this, and one long head 21 may be provided for each ink image forming unit 20 instead of the plurality of heads 21. In the above embodiment, the UV ink is ejected in a state where each head 21 is fixed at a predetermined position. However, the UV ink is ejected while the head 21 moves along the axial direction of the intermediate transfer body 31. (That is, the printer 1 is a serial type).

  In the above-described embodiment, the intermediate transfer member 31 is a drum-shaped rotating member. However, it is not limited to this, For example, an endless belt-like rotary body may be sufficient.

  In the above-described embodiment, the medium S is described as an example of the transfer target, but the present invention is not limited to this. For example, the transfer of the UV ink by the intermediate transfer body 31 may be performed not on the medium S but on the second intermediate transfer body (in this case, the transfer of the UV ink to the medium S is, for example, the second Intermediate transfer member).

  Further, the linear velocity of the intermediate transfer member 31 of one intermediate transfer member unit 18 among the plurality of intermediate transfer member units 18 and the linear velocity of the intermediate transfer member 31 of the other intermediate transfer member unit 18 are different from each other. Also good. Thus, by making the linear velocities different from each other, the above-described gap filling at the time of transfer can be freely changed between the intermediate transfer body units 18 (between ink colors). This makes it possible to expand image variations (to obtain images having various types of image characteristics).

  As an example, the linear velocity for the yellow intermediate transfer unit 18Y among the four intermediate transfer units 18K, 18C, 18M, and 18Y is greater than the linear velocity for the other intermediate transfer units 18K, 18C, and 18M. May be accelerated. As a method for realizing such matters, a method of increasing the peripheral speed of the intermediate transfer body 31 of the yellow intermediate transfer body unit 18Y, or an intermediate transfer body 31 of the yellow intermediate transfer body unit 18Y having the same peripheral speed as shown in FIG. There is a method of increasing the diameter of either, and either may be used. FIG. 12 is a diagram illustrating main components of the printer 1 according to another embodiment.

1 printer, 10 controller, 11 interface, 12 CPU, 13 memory, 14 unit control circuit, 18 intermediate transfer unit, 18K black intermediate transfer unit, 18C cyan intermediate transfer unit, 18M magenta intermediate transfer unit, 18Y yellow intermediate Transfer body unit, 20 Ink image forming unit, 21 Head, 22 Nozzle surface, 23 Semi-cured irradiation section, 24 Light source, 31 Intermediate transfer body, 32 Pressing roller, 33 Peripheral surface, 34 Gap, 40 Transport unit, 41 Transport roller, 50 fixing unit, 51 light source, 60 detector group, 110 host computer, 120 ink image forming unit, 120K black ink image forming unit, 120C cyan ink image forming unit, 120M magenta ink image Forming unit, 120Y yellow ink image forming unit, S medium

Claims (2)

A head for ejecting ultraviolet curable ink which is cured by receiving ultraviolet rays;
An intermediate transfer member for transferring the ultraviolet curable ink to the transfer target after receiving the ultraviolet curable ink ejected by the head;
A plurality of intermediate transfer body units having a semi-curing irradiation section for irradiating the ultraviolet curable ink on the intermediate transfer body with ultraviolet rays to make the ultraviolet curable ink semi-cured,
The head performs a jetting operation of jetting the ultraviolet curable ink a plurality of times,
The intermediate transfer member is
An attachment surface to which the ultraviolet curable ink is attached; and
Both the ultraviolet curable ink ejected from the head in one ejection operation of the plurality of ejection operations and the ultraviolet curable ink ejected from the head in the ejection operation subsequent to the one ejection operation. However, by pressing the adhering surface adhering across the gap formed between the two against the transfer target, the both are transferred to the transfer target while crushing the gap so that the gap is filled. And
The intermediate transfer body is a rotatable rotator provided with a peripheral surface as the attachment surface, and the peripheral surface of the rotating rotator is pressed against a medium as the transfer target, Transfer both to the medium,
A transport unit that transports the medium so that the medium passes through a transfer position where the intermediate transfer member transfers both of the media to the medium;
The linear velocity of the rotating body at the transfer position is different from the moving speed of the medium when passing through the transfer position,
An ink ejecting apparatus , wherein a linear velocity of the rotating body of one intermediate transfer body unit and a linear velocity of the rotating body of another intermediate transfer body unit are different from each other . Each head provided in the plurality of intermediate transfer body units ejects ultraviolet curable ink that is cured by receiving ultraviolet rays; and
Each intermediate transfer member provided in the plurality of intermediate transfer member units receives the ultraviolet curable ink ejected by each head;
Each of the semi-curing irradiation units provided in the plurality of intermediate transfer body units irradiates the ultraviolet curable ink on each of the intermediate transfer bodies with ultraviolet rays so that the ultraviolet curable ink is in a semi-curing state. When,
Each of the intermediate transfer members transfers the ultraviolet curable ink to a transfer target;
An ink jetting method comprising:
The head performs a jetting operation of jetting the ultraviolet curable ink a plurality of times,
The intermediate transfer member is
An attachment surface to which the ultraviolet curable ink is attached; and
Both the ultraviolet curable ink ejected from the head in one ejection operation of the plurality of ejection operations and the ultraviolet curable ink ejected from the head in the ejection operation subsequent to the one ejection operation. However, by pressing the adhering surface adhering across the gap formed between the two against the transfer target, the both are transferred to the transfer target while crushing the gap so that the gap is filled. And
The intermediate transfer body is a rotatable rotator provided with a peripheral surface as the attachment surface, and the peripheral surface of the rotating rotator is pressed against a medium as the transfer target, Transfer both to the medium,
A transport unit that transports the medium so that the medium passes through a transfer position where the intermediate transfer member transfers both of the media to the medium;
The linear velocity of the rotating body at the transfer position is different from the moving speed of the medium when passing through the transfer position,
An ink ejecting method , wherein a linear velocity of the rotating body of one intermediate transfer body unit of the plurality of intermediate transfer body units and a linear velocity of the rotating body of another intermediate transfer body unit are different from each other .