JP2011016313A - Liquid ejection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a medium from curling which is caused by solidifying a dot completely on the peripheral surface of a carrying member.SOLUTION: A liquid ejection device includes: a carrying member of cylindrical shape for carrying the medium in the peripheral surface; a head which is located opposite to the peripheral surface of the carrying member and forms the dot in the medium on the carrying member by ejecting the liquid cured by irradiating an electromagnetic wave; and an irradiation part which irradiates the electromagnetic wave to the dot of the medium after the medium after dot formation separates from the carrying member.

Description

  The present invention relates to a liquid ejecting apparatus.

  There is known a liquid ejecting apparatus that performs printing using a liquid (for example, UV ink) that is cured by irradiation with an electromagnetic wave (for example, ultraviolet (UV)). In such a liquid ejecting apparatus, a liquid is ejected from a nozzle of a head onto a medium (paper, film, etc.), and then an electromagnetic wave is irradiated onto dots formed on the medium. By doing so, the dots are cured and fixed to the medium, so that it is possible to perform good printing even on a medium that hardly absorbs liquid (for example, see Patent Document 1).

JP 2000-158793 A

The liquid ejection apparatus as described above includes a cylindrical conveyance member (for example, a conveyance drum) and a head provided so as to face the circumferential surface of the conveyance member, and conveys a medium on the circumferential surface of the conveyance member. However, there is a printer that prints an image on a medium by ejecting ink from a head. In this case, if the dots are completely solidified on the peripheral surface of the transport member, the medium may be curled.
An object of the present invention is to prevent curling of a medium.

A main invention for achieving the above object is a cylindrical transport member that transports a medium on a peripheral surface, and a head that is provided to face the peripheral surface of the transport member, and is irradiated with electromagnetic waves. A head for ejecting a liquid to be cured to form dots on the medium on the conveying member, and an irradiation unit for irradiating the dots on the medium with electromagnetic waves after the medium after the dot formation has separated from the conveying member And a liquid ejecting apparatus.
Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

1 is a block diagram of the overall configuration of a printer. FIG. 3 is a schematic view around a print area. It is explanatory drawing of the nozzle arrangement | positioning of each head. 4A to 4C are explanatory diagrams of the relationship between the timing of UV irradiation in temporary curing and the shape of UV ink (dots). It is a figure which shows the 1st comparative example about arrangement | positioning of the irradiation part 44 for main curing. It is a figure which shows the 2nd comparative example about arrangement | positioning of the irradiation part 44 for main curing. It is a flowchart of the printing process by the printer 1 of this embodiment. It is the schematic of the printing area periphery of 2nd Embodiment. It is the schematic which shows the state of the paper S at the time of the main curing in 2nd Embodiment. It is a figure which shows an example which changed arrangement | positioning of the downstream conveyance roller 21B.

  At least the following matters will become clear from the description of the present specification and the accompanying drawings.

A cylindrical conveyance member that conveys a medium on a circumferential surface, and a head that is provided to face the circumferential surface of the conveyance member, and discharges a liquid that is cured by being irradiated with electromagnetic waves, thereby conveying the medium A liquid comprising: a head that forms dots on the medium on a member; and an irradiation unit that irradiates electromagnetic waves to the dots of the medium after the medium on which the dots have been formed is separated from the conveying member. The discharge device becomes clear.
According to such a liquid ejecting apparatus, curling of the medium can be prevented.

In this liquid ejecting apparatus, it is preferable that when the irradiation unit emits electromagnetic waves, the medium is inclined in the direction of gravity, and a dot formation surface is downward in the direction of gravity.
According to such a liquid ejecting apparatus, it is possible to prevent dust and mist from adhering to the dot formation surface while preventing curling of the medium.

In the liquid ejecting apparatus, the irradiation unit may emit electromagnetic waves to the medium before the radius of curvature in the conveyance path of the medium after separating from the conveyance member becomes smaller than the radius of curvature at the time of dot formation. Irradiation is desirable.
According to such a liquid ejecting apparatus, it is possible to prevent deterioration in image quality.

A transport roller having a radius smaller than that of the transport member, the transport roller being in contact with a dot formation surface of the medium separated from the transport member; and the irradiating unit in front of the transport roller It is desirable to irradiate.
According to such a liquid ejecting apparatus, it is possible to prevent ink from adhering to the transport roller.

In this liquid ejecting apparatus, the head processes a surface of the medium at a downstream side of the first head for ejecting a liquid for printing an image and a transport direction of the medium from the first head. And a second head for injecting a processing liquid, and it is desirable to have a temporary curing irradiation unit that irradiates an electromagnetic wave having an irradiation intensity lower than that of the irradiation unit between the first head and the second head. .
According to such a liquid ejecting apparatus, it is possible to increase gloss and improve image quality.

  In the following embodiments, a printer (printer 1) will be described as an example of the liquid ejecting apparatus.

=== First Embodiment ===
<About printer configuration>
FIG. 1 is a block diagram of the overall configuration of the printer 1. FIG. 2 is a schematic view around the print area.
The printer 1 is a printing device that prints an image on a medium such as paper, cloth, or film, and is communicably connected to a computer 110 that is an external device.
A printer driver is installed in the computer 110. The printer driver is a program for displaying a user interface on a display device (not shown) and converting image data output from an application program into print data. This printer driver is recorded on a recording medium (computer-readable recording medium) such as a flexible disk FD or a CD-ROM. Alternatively, the printer driver can be downloaded to the computer 110 via the Internet. In addition, this program is comprised from the code | cord | chord for implement | achieving various functions.
Then, the computer 110 outputs print data corresponding to the image to be printed to the printer 1 in order to cause the printer 1 to print an image.

  The printer 1 according to the present embodiment is an apparatus that prints an image on a medium by ejecting ultraviolet curable ink (hereinafter, UV ink) that is cured by irradiation with ultraviolet rays (hereinafter, UV) as an example of a liquid. The UV ink is an ink containing an ultraviolet curable resin, and is cured by undergoing a photopolymerization reaction in the ultraviolet curable resin when irradiated with UV. Note that the printer 1 of the present embodiment prints an image using four colors of UV ink (color ink) of cyan, magenta, yellow, and black.

  The printer 1 includes a transport unit 20, a head unit 30, an irradiation unit 40, a detector group 50, and a controller 60. The printer 1 that has received print data from the computer 110 that is an external device controls each unit (the transport unit 20, the head unit 30, and the irradiation unit 40) by the controller 60, and prints an image on a medium according to the print data. The controller 60 controls each unit based on the print data received from the computer 110 and prints an image on a medium. The situation in the printer 1 is monitored by the detector group 50, and the detector group 50 outputs the detection result to the controller 60. The controller 60 controls each unit based on the detection result output from the detector group 50.

The transport unit 20 is for transporting a medium (for example, paper S) in a predetermined direction (hereinafter referred to as a transport direction). The transport unit 20 includes an upstream transport roller 21 </ b> A, a downstream transport roller 21 </ b> B, and a transport drum 22.
The upstream side conveyance roller 21 </ b> A is provided at the lower left position of the conveyance drum 22 in the drawing. Further, the downstream side conveyance roller 21 </ b> B is provided at a position lower than the conveyance drum 22 in the gravity direction and away from the conveyance drum 22. As the upstream-side transport roller 21A and the downstream-side transport roller 21B rotate, the medium is transported and the transport drum 22 rotates.
The transport drum 22 is a cylindrical transport member, and transports the long paper S wound in a roll shape on the peripheral surface. In the present embodiment, as shown in FIG. 2, the radius of the transport drum 22 is R, and the radius of the downstream transport roller 21B is r (<R).
The paper S is supplied from an upstream paper feed roll (not shown) and taken up by a downstream take-up roller (not shown). Further, the paper S is transported so as to be in close contact with the transport drum 22 with a predetermined tension.

The head unit 30 is for ejecting UV ink onto a medium. The head unit 30 ejects ink from each head to the medium being transported, thereby forming dots on the medium and printing an image on the medium. Note that each head of the head unit 30 of the printer 1 of the present embodiment can form dots for the medium width at a time. In this embodiment, four color inks for forming an image are used as the UV ink. As shown in FIG. 2, in order from the upstream side in the transport direction, a black ink head K that ejects black UV ink, a cyan ink head C that ejects cyan UV ink, and a magenta ink head M that ejects magenta UV ink. The yellow ink head Y that ejects yellow UV ink is provided so as to face the peripheral surface of the transport drum 22. Hereinafter, each head that ejects color ink (black, cyan, magenta, yellow) is also referred to as a color ink head. The dots formed by the color ink head are also called color dots.
Details of the configuration of the head unit 30 will be described later.

  The irradiation unit 40 irradiates UV toward the UV ink that has landed on the medium. The dots formed on the medium are cured by receiving UV irradiation from the irradiation unit 40. The irradiation unit 40 of the present embodiment includes provisional curing irradiation units 42 a to 42 e and a main curing irradiation unit 44.

The pre-curing irradiation units 42a to 42e irradiate UV for pre-curing the dots formed on the medium. The provisional curing irradiation unit 42 a is provided on the downstream side in the transport direction of the black ink head K, and the provisional curing irradiation unit 42 b is provided on the downstream side in the transport direction of the cyan ink head C. The provisional curing irradiation unit 42c is provided on the downstream side in the transport direction of the magenta ink head M, and the provisional curing irradiation unit 42d is provided on the downstream side in the transport direction of the yellow ink head Y. Further, the pre-curing irradiation part 42e is provided on the downstream side in the transport direction of the clear ink head CL.
The length in the medium width direction of these pre-curing irradiation units 42a to 42e is equal to or greater than the medium width, and the dots formed on the medium by each head can be irradiated with UV light for pre-curing. In the present embodiment, temporary curing is curing performed to suppress bleeding between inks and dot spreading.

The pre-curing irradiation units 42a to 42e of the present embodiment include light emitting diodes (LEDs) as UV light sources. The LED can easily change the irradiation intensity by controlling the magnitude of the input current.
The details of temporary curing will be described later.

The main curing irradiation section 44 irradiates UV for main curing dots formed on the medium by each head, and is provided between the transport drum 22 and the downstream transport roller 21B. The reason why the main curing irradiation section 44 is disposed at this position will be described later. The length of the main curing irradiation unit 44 in the medium width direction is equal to or greater than the medium width. In the present embodiment, the main curing is curing performed to completely solidify the dots.
The main curing irradiation unit 44 of the present embodiment includes a lamp (a metal halide lamp, a mercury lamp, or the like) as a UV irradiation light source.
As shown in the drawing, the main curing irradiation unit 44 of the present embodiment irradiates UV for main curing toward the printing surface of the paper S between the transport drum 22 and the downstream transport roller 21B.
Details of the main curing will be described later.

  The detector group 50 includes a rotary encoder (not shown), a paper detection sensor (not shown), and the like. The rotary encoder detects the rotation amount of the upstream side conveyance roller 21A and the downstream side conveyance roller 21B. The transport amount of the medium can be detected based on the detection result of the rotary encoder.

  The controller 60 is a control unit (control unit) for controlling the printer. The controller 60 includes an interface unit 61, a CPU 62, a memory 63, and a unit control circuit 64. The interface unit 61 transmits and receives data between the computer 110 that is an external device and the printer 1. The CPU 62 is an arithmetic processing unit for controlling the entire printer. The memory 63 is for securing an area for storing a program of the CPU 62, a work area, and the like, and includes storage elements such as a RAM and an EEPROM. The CPU 62 controls each unit via the unit control circuit 64 in accordance with a program stored in the memory 63.

<About the configuration of the head>
As described above, the printer 1 of the present embodiment includes four color ink heads (black ink head K, cyan ink head C, magenta ink head M, and yellow ink head Y). Each of these heads ejects UV ink (color ink) for printing an image for each ink color.

FIG. 3 is an explanatory diagram of an example of the nozzle arrangement of each head.
As shown in the drawing, each head includes two nozzle rows of “A row” and “B row” as shown in the drawing.
The nozzles in each row are arranged at an interval (nozzle pitch) of 1/180 inch along a direction (nozzle row direction) intersecting the transport direction. Further, the position in the nozzle row direction of the nozzles in the A row and the position in the nozzle row direction of the nozzles in the B row are shifted by a half nozzle pitch (1/360 inch). As a result, color dots can be formed with a resolution of 1/360 inch.
Note that the length of each nozzle row in the nozzle row direction (paper width direction) is equal to or longer than the length corresponding to the medium width, whereby dots corresponding to the medium width can be formed at a time.

<About temporary curing and main curing>
The printer 1 according to the present embodiment includes provisional curing irradiation units 42a to 42d and a main curing irradiation unit 44 as the irradiation unit 40, and performs two-stage curing, that is, temporary curing and main curing after the dots are formed. ing. Hereinafter, the function of each curing will be described.

Temporary curing is curing for suppressing bleeding between inks and spreading of dots by curing the surface of the dots. The amount of UV irradiation applied to the dots during this temporary curing is small, and the UV ink (dots) is not completely solidified even after the temporary curing. The irradiation amount (mJ / cm ² ) is the product of irradiation intensity (mW / cm ² ) and irradiation time (sec). In this embodiment, since the medium conveyance speed is constant (irradiation time by each irradiation unit is constant), the irradiation amount depends on the irradiation intensity.

4A to 4C are explanatory diagrams of the relationship between the timing of UV irradiation in temporary curing and the shape of UV ink (dots). Note that the UV irradiation timing is delayed in the order of FIGS. 4A, 4B, and 4C.
When the UV irradiation timing is early, for example, as shown in FIG. 4A. In this case, it is possible to suppress bleeding between inks and spread of dots, but the gloss becomes worse because the unevenness of the medium surface constituted by the dots becomes large.
On the other hand, when the UV irradiation timing is late, for example, as shown in FIG. 4C. In this case, the gloss is good. However, bleeding tends to occur between other inks.

  The main curing is a curing for completely solidifying the ink. The UV irradiation amount in the main curing is larger than the UV irradiation amount in the temporary curing.

  By performing temporary curing after dot formation in this way, it is possible to suppress bleeding between inks and spread of dots, and it is possible to prevent deterioration in image quality regardless of the timing of performing main curing. In the present embodiment, provisional curing irradiation units are provided on the downstream side in the transport direction of the heads of the respective colors, and provisional curing is performed immediately after the formation of the dots of the respective colors.

<Regarding the position of the main curing irradiation section>
(First comparative example)
FIG. 5 is a diagram illustrating a first comparative example regarding the arrangement of the main curing irradiation unit 44. In the figure, the configuration is the same as in FIG. 2 except for the arrangement of the main curing irradiation section 44.
In the first comparative example, the main curing irradiation unit 44 is disposed downstream of the temporary curing irradiation unit 42 d in the transport direction and at a position facing the peripheral surface of the transport drum 22.

As described above, in the present embodiment, a lamp (for example, a metal halide lamp) is used as the light source of the main curing irradiation unit 44. This generates more heat than the LEDs of the light sources of the pre-curing irradiation units 42a to 42d. Therefore, in this case, the conveyance drum 22 is heated by the UV irradiation of the main curing. Also, as shown in the enlarged portion of the figure, the dots harden in a state where the paper S is curved along the peripheral surface of the transport drum. Since the circumferential surface of the conveyance drum 22 is a circle, the curvature and the radius of curvature are the same on the circumferential surface of the conveyance drum 22 (curvature: 1 / R, curvature radius: R). Note that the radius of curvature is a radius obtained by approximating a local curve of a curve (curved surface) to a circle. The curvature is the reciprocal of the radius of curvature.
Therefore, in the first comparative example, the dots on the paper S are completely solidified in a state where the paper S is curved with a curvature 1 / R. For this reason, the paper S may be curled. Further, the transport drum 22 is heated by the UV irradiation of the main curing irradiation unit 44.

(Second comparative example)
FIG. 6 is a diagram illustrating a second comparative example regarding the arrangement of the main curing irradiation unit 44. In the figure, the configuration is the same as in FIG. 2 except for the arrangement of the main curing irradiation section 44.
From the first comparative example, in order to prevent the conveyance drum 22 from being heated and to prevent the paper S from curling, the main curing is not performed on the conveyance drum 22 but in a flat place away from the conveyance drum 22. It turns out to be desirable.
Therefore, in the second comparative example, the main curing irradiation unit 44 is disposed at a location where the paper S is transported flatly on the downstream side in the transport direction with respect to the downstream transport roller 21B.

  However, in this case, since the radius of the downstream transport roller 21B is r (<R), the radius of curvature when passing through the downstream transport roller 21B is smaller than the radius of curvature during printing (during dot formation). In the transport path of the paper S after printing, the radius of curvature is R (on the peripheral surface of the transport drum 22) → infinity (where the paper S between the transport drum 22 and the downstream transport roller 21B is flat) → r (On the peripheral surface of the downstream side transport roller 21B) → infinitely (continuously changing from the downstream side transport roller 21B to the downstream side in the transport direction).

  In this way, since there is a place where the radius of curvature is smaller than that at the time of printing (a place where the curvature becomes larger) in the transport path until the main curing is performed, the dot shape formed on the paper S at this time is deformed, The image quality may be degraded. Further, since the dots on the printing surface of the paper S that is not completely solidified are in contact with the downstream side transport roller 21B, there is a possibility that the ink adheres to the downstream side transport roller 21B.

  Further, in this case, the paper S after passing through the downstream side transport roller 21B is transported with the print surface facing upward in the direction of gravity, so that dust and mist adhere to the print surface until the book is cured. The possibility increases. The mist is a minute ink droplet that is generated when an ink droplet is ejected from the nozzle of the head.

(This embodiment)
In this embodiment, as shown in FIG. 2, after the main curing irradiation unit 44 is arranged on a flat surface between the transport drum 22 and the downstream transport roller 21 </ b> B and the paper S is separated from the transport drum 22. The main curing is performed before the radius of curvature becomes smaller than when printing (dot formation) (that is, before the downstream side transport roller 21B). By doing so, the paper S can be prevented from curling as compared with the first comparative example. Further, the conveyance drum 22 can be prevented from being heated.
In addition, during the main curing, the paper S is inclined in the direction of gravity, and the printing surface is directed downward in the direction of gravity. Mist is hard to adhere. In addition, since the main curing is performed before the downstream side conveyance roller 21B, it is possible to prevent image quality deterioration due to a decrease in the radius of curvature when passing through the downstream side conveyance roller 21B. Further, even if the printing surface of the paper S is in contact with the downstream transport roller 21B, it is possible to prevent ink from adhering to the downstream transport roller 21B.

<About print processing>
When the printer 1 starts printing, the paper S is supported by the upstream-side transport roller 21 </ b> A and the downstream-side transport roller 21 </ b> B in a state in which the paper S is laid along the peripheral surface of the transport drum 22 in advance.
When the printer 1 receives print data from the computer 110, the controller 60 rotates a transport motor (not shown) at a constant speed. Thereby, the upstream side conveyance roller 21A and the downstream side conveyance roller 21B rotate at a constant speed in the direction of the arrow in the figure. In addition, this rotation causes the transport drum 22 to rotate in the direction of the arrow (transport direction). The paper S along the peripheral surface of the transport drum 22 and supported by the upstream transport roller 21 </ b> A and the downstream transport roller 21 </ b> B is transported in the transport direction according to the rotation of the transport drum 22. Note that the paper S being transported is electrostatically attracted or vacuum attracted to the transport drum 22.
The controller 60 forms dots on the medium by intermittently ejecting ink from the nozzles of each head of the head unit 30 based on the print data while the paper S is being transported on the peripheral surface of the transport drum 22. At the same time, UV is irradiated from each irradiation section of the irradiation unit 40.

FIG. 7 is a flowchart of print processing by the printer 1 of the present embodiment.
First, when the paper S passes under the black ink head K, black ink is ejected from the black ink head K to print black (S101). Then, after printing black, UV is irradiated from the pre-curing irradiation unit 42a to perform pre-curing of dots formed with black ink (S102).

  Next, when the paper S passes under the cyan ink head C, the controller 60 ejects cyan ink from the cyan ink head C to print cyan (S103). Then, after the printing, UV is irradiated from the pre-curing irradiation section 42b to perform pre-curing of the dots formed with the cyan ink (S104).

  Similarly, the controller 60 ejects magenta ink from the magenta ink head M to print magenta (S105), and irradiates UV from the pre-curing irradiation unit 42c to temporarily cure the dots formed with magenta ink. (S106). Further, yellow ink is ejected from the yellow ink head Y to print yellow (S107), UV is irradiated from the pre-curing portion irradiation unit 42d, and the dots formed with the yellow ink are temporarily cured (S108).

  Finally, the controller 60 performs main curing of each dot on the paper S by irradiating UV from the main curing irradiation unit 44 (S109). At this time, as shown in FIG. 2, the paper S is located away from the transport drum 22 and is inclined at a predetermined angle in the direction of gravity. At this time, the printing surface of the paper S faces downward in the direction of gravity. And UV is irradiated from the irradiation part 44 for main curing toward the printing surface. Thereby, each dot on the paper S is completely solidified.

  As described above, in the present embodiment, after the printed paper S leaves the transport drum 22, the main curing is performed in a state where the paper S is transported flat, and thus curling of the paper S is prevented. Can do. Further, the conveyance drum 22 can be prevented from being heated. In addition, since the main curing is performed before the radius of curvature becomes smaller than the radius of curvature at the time of printing, it is possible to prevent deterioration in image quality. Furthermore, since the printing surface of the paper S faces downward in the direction of gravity during the main curing, it is possible to prevent dust and mist from adhering to the printing surface.

  The paper S after the main curing is transported downstream in the transport direction (right side in the drawing) via the downstream transport roller 21B. At this time, the printing surface of the paper S comes into contact with the downstream conveyance roller 21B. In this embodiment, since the main curing is performed before the downstream conveyance roller 21B, the ink is transferred to the downstream conveyance roller 21B. It can be prevented from sticking.

=== Second Embodiment ===
FIG. 8 is a schematic view of the periphery of the print area according to the second embodiment. In FIG. 8, the same components as those in FIG. Compared to the first embodiment (FIG. 2), the difference is that a clear ink head CL is provided.
The clear ink head CL (corresponding to the second head) ejects a colorless and transparent clear ink (a kind of processing liquid) that cures when irradiated with UV, and is transported more than the provisional curing irradiation unit 42d. It is provided on the downstream side in the direction so as to face the transport drum 22.

In the second embodiment, after image printing (that is, formation of color dots and provisional curing), clear ink is ejected from the clear ink head CL and the clear ink is applied onto the paper S. Thus, when the clear ink is applied after the image is printed, the gloss of the medium surface can be increased.
And after apply | coating clear ink, UV is irradiated to the printing surface of the paper S from the irradiation part 44 for main curing, and main curing is performed.
In addition, after applying clear ink application to the paper S, provisional curing is not performed. This is because in the case of color inks, bleeding occurs when the inks are mixed, but since clear ink is a colorless and transparent ink, bleeding does not occur as in the case of color inks even if the inks are mixed. When applying the clear ink, the color ink (color dot) has already been temporarily cured, so no bleeding occurs between the clear ink and the color ink.
As described above, since the spread of the clear ink (clear dots) is increased by not performing the temporary curing after the clear ink is applied, the surface of the paper S can be smoothed, thereby further increasing the gloss. it can. Note that after the clear ink application, the UV irradiation may be performed with an irradiation intensity weaker than the irradiation intensity of the pre-curing irradiation units 42a to 42d.

<About the state at the time of main curing>
FIG. 9 is a schematic diagram showing the state of the paper S during the main curing in the second embodiment.
In the present embodiment, the clear ink (clear dots) is not temporarily cured after the clear ink is applied to the paper S after the color dots are formed. Therefore, the clear dots are in a state that is easy to spread. Here, at the time of the main curing, as shown in the figure, the printing surface of the paper S faces downward in the gravity direction, and the paper S (the conveyance direction of the paper S) is inclined obliquely in the gravity direction. For this reason, the gravity acting on the dots formed on the medium is divided into a component force (a1) parallel to the slope of the medium and a component force (a2) in the direction perpendicular to the slope. Further, when the paper S is transported in the transport direction, the clear dot receives an air resistance (b) opposite to the transport direction. The spread of clear dots is promoted according to each of these forces. For example, the air resistance b increases as the conveyance speed increases, and decreases as the conveyance speed decreases. Further, when the inclination of the paper S in the direction of gravity is large, the component force a1 increases and the component force a2 decreases. On the other hand, when the inclination in the direction of gravity is small, the component force a2 increases and the component force a1 decreases. Therefore, if the conveyance speed is increased and the inclination in the gravity direction of the paper S is increased, even if there is a step due to color dots as shown in the figure, the step of the clear ink (clear dot) applied thereon is reduced. Can do. That is, the surface becomes flatter and gloss can be increased.

  In this way, the paper S is inclined in the direction of gravity between the application of the clear ink to the paper S and the main curing, and the printing surface of the paper S is directed downward in the direction of gravity. The surface of the ink (clear dot) can be smoothed. As a result, the gloss can be increased.

Further, as in the above-described embodiment, since the main curing is performed at a position away from the peripheral surface of the transport drum 22, curling of the paper S can be prevented. Further, the conveyance drum 22 can be prevented from being heated by the UV irradiation of the main curing. Furthermore, since the main curing is performed in front of the downstream conveyance roller 21B, the printing surface of the paper S is the same as the downstream conveyance roller 21B. Even if it comes into contact, it is possible to prevent ink from adhering to the downstream-side transport roller 21B.

=== Other Embodiments ===
Although a printer or the like as one embodiment has been described, the above embodiment is for facilitating the understanding of the present invention, and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof. In particular, the embodiments described below are also included in the present invention.

<About the printer>
In the above-described embodiment, a printer has been described as an example of an apparatus, but the present invention is not limited to this. For example, color filter manufacturing apparatus, dyeing apparatus, fine processing apparatus, semiconductor manufacturing apparatus, surface processing apparatus, three-dimensional modeling machine, liquid vaporizer, organic EL manufacturing apparatus (particularly polymer EL manufacturing apparatus), display manufacturing apparatus, film formation The same technology as that of the present embodiment may be applied to various printing apparatuses to which ink jet technology is applied, such as an apparatus and a DNA chip manufacturing apparatus.

<About ink>
In the above-described embodiment, ink that is cured by receiving ultraviolet (UV) irradiation (UV ink) is ejected from the nozzle. However, the liquid ejected from the nozzle is not limited to such ink, and a liquid that is cured by receiving irradiation of electromagnetic waves other than UV (for example, visible light) may be ejected from the nozzle. In this case, electromagnetic waves (such as visible light) for curing the liquid may be irradiated from the temporary curing irradiation unit and the main curing irradiation unit.

<About clear ink>
In the second embodiment, the colorless and transparent clear ink is used to form dots other than the image. However, the present invention is not limited to the clear ink. For example, it may be a translucent processing liquid that gives the surface of the medium gloss. Further, the processing does not have to be glossy. A working fluid that adjusts the texture of the surface of the medium may be used.

<About temporary curing>
In the embodiment described above, the temporary curing is performed after the color dots of the respective colors are formed by the temporary curing irradiation units 42a to 42d. However, the temporary curing may not be performed. Alternatively, temporary curing may be performed after all color dots are formed on the paper S. In this case, the image quality may be deteriorated, but curling of the paper S can be prevented by performing the main curing when the paper S is flat as shown in FIG.

<About main curing>
In the above-described embodiment, the paper S is inclined at a predetermined angle in the direction of gravity during the main curing, but the paper S may be parallel to the direction of gravity. Further, the paper S may be conveyed in a direction intersecting with the gravity direction. In the above-described embodiment, the printing surface of the paper S faces downward in the gravitational direction at the time of the main curing, but may face upward in the gravitational direction. In this case, there is a high possibility that dust and mist will adhere to the printing surface, but curling of the paper S can be prevented by main-curing the paper S in a flat state.

<About the downstream transport roller>
In the above-described embodiment, the downstream transport roller 21B is in contact with the printing surface of the paper S. However, the downstream transport roller 21B may not be in contact with the printing surface of the paper S.
FIG. 10 is a diagram illustrating an example in which the arrangement of the downstream conveyance rollers 21B is changed.
In the figure, the configuration other than the arrangement of the downstream-side transport roller 21B and the main curing irradiation unit 44 is the same as that in FIG.
In this case, the position where the paper S is separated from the top of the transport drum 22 is located above the center of the transport drum 22 in the direction of gravity, and the downstream transport roller 21B is positioned on the right side of the right end of the transport drum 22. In addition, it is provided below the center of the transport drum 22 in the direction of gravity.
And the downstream conveyance roller 21B conveys the paper S in contact with the surface (back surface) opposite to the printing surface of the paper S by rotating in the direction opposite to that in the case of FIG. Even in this case, the radius of curvature is smaller than that during printing when passing the downstream side conveyance roller 21B. Therefore, it is desirable that the main curing irradiation unit 44 is disposed in front of the downstream side transport roller 21B as shown in the figure, and the main curing is performed before the paper S reaches the transport roller 21B.

1 printer,
20 transport unit, 21A upstream transport roller, 21B downstream transport roller,
22 transport drum,
30 head units, 40 irradiation units,
42a to 42d Preliminary curing irradiation unit, 44 Regular curing irradiation unit,
50 detector groups, 60 controllers, 61 interface units, 62 CPUs,
63 memory, 64 unit control circuit,
110 Computer K Black ink head, C Cyan ink head,
M magenta ink head, Y yellow ink head,
CL clear ink head

Claims (5)

A cylindrical conveying member for conveying the medium on the peripheral surface;
A head provided opposite to the peripheral surface of the transport member to eject a liquid that is cured by being irradiated with electromagnetic waves to form dots on the medium on the transport member;
An irradiation unit that irradiates the dots of the medium with electromagnetic waves after the medium after the dot formation is separated from the conveying member;
A liquid ejecting apparatus comprising: The liquid ejecting apparatus according to claim 1,
The liquid ejecting apparatus according to claim 1, wherein when the irradiation unit irradiates electromagnetic waves, the medium is inclined in the direction of gravity, and a dot formation surface is downward in the direction of gravity. The liquid ejecting apparatus according to claim 1 or 2,
The irradiation unit irradiates the medium with electromagnetic waves before the radius of curvature in the conveyance path of the medium after being separated from the conveyance member becomes smaller than the radius of curvature at the time of dot formation. Injection device. The liquid ejecting apparatus according to claim 3,
A conveyance roller having a smaller radius than the conveyance member, the conveyance roller being in contact with the formation surface of the dot of the medium away from the conveyance member;
The said irradiation part irradiates the said electromagnetic waves before the said conveyance roller, The liquid ejecting apparatus characterized by the above-mentioned. The liquid ejecting apparatus according to claim 1,
The head is
A first head that ejects liquid for printing an image;
A second head that ejects a working fluid for processing the surface of the medium on the downstream side of the medium in the transport direction of the medium;
Including
A liquid ejecting apparatus comprising: an irradiation unit for temporary curing that irradiates an electromagnetic wave having an irradiation intensity lower than that of the irradiation unit between the first head and the second head.

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