JP2011073328A - Printer and printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the image quality of printing in printing using an ultraviolet-curable ink. <P>SOLUTION: The printer has a head which ejects the ultraviolet-curable ink to a medium; a temporary curing irradiation part which emits ultraviolet rays, irradiates the ultraviolet-curable ink on the medium with the ultraviolet rays and temporarily cures the ultraviolet-curable ink; and a diffusing member which diffuses the ultraviolet rays emitted by the temporary curing irradiation part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a printing apparatus and a printing method.

  In the printing field, it is already well known to use ultraviolet curable ink (also referred to as UV ink) that is cured by irradiation with ultraviolet light (also referred to as UV). As a printing technique using such UV ink, for example, an ink jet printer that performs printing by discharging UV ink onto various media such as paper and film is known.

  A printing apparatus having a head that discharges ultraviolet curable ink onto a medium and an irradiation unit that emits ultraviolet light and irradiates the ultraviolet curable ink on the medium to cure the ultraviolet curable ink is already known. (For example, refer to Patent Document 1).

JP 2000-158793 A

  By the way, when performing printing in such a printing apparatus, before the ultraviolet curable ink is cured by irradiating the ultraviolet rays, the ultraviolet curable ink is temporarily cured by irradiating the ultraviolet rays to a degree that suppresses the spread of the ultraviolet curable ink. May be performed. In such a case, the printed image may not be sufficiently glossy and a desired image quality may not be obtained.

  SUMMARY An advantage of some aspects of the invention is that it provides a printing apparatus and a printing method capable of obtaining a desired image quality.

The main invention for achieving the above object is:
A head for discharging ultraviolet curable ink onto a medium;
A temporary curing irradiation unit that emits ultraviolet rays, irradiates the ultraviolet curable ink on the medium with the ultraviolet rays, and temporarily cures the ultraviolet curable ink;
A diffusion member that diffuses the ultraviolet rays emitted by the pre-curing irradiation section;
It is a printing apparatus characterized by having.
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 illustrating a configuration of a printer according to an embodiment of the present invention. FIG. 2 is a schematic view around a head of the printer of FIG. 1. 3A and 3B are cross-sectional views of the printer of FIG. It is explanatory drawing of a structure of the head shown in FIG. It is a figure which shows an example of the diffusion member by this invention. It is a figure which shows the other example of the diffusion member by this invention.

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

A head for discharging ultraviolet curable ink onto a medium;
A temporary curing irradiation unit that emits ultraviolet rays and irradiates the ultraviolet curable ink on the medium with the ultraviolet rays to temporarily cure the ultraviolet curable ink;
A diffusion member that diffuses the ultraviolet rays emitted by the pre-curing irradiation section;
A printing apparatus characterized by having:
According to such a printing apparatus, the UV ink spreads and is smoothed (leveled), the gloss of the printed image is increased, and a desired image quality can be obtained.

  In such a printing apparatus, the diffusion member may be a Fresnel lens.

  In the printing apparatus, the diffusing member may be a reflecting plate.

Also,
Discharging ultraviolet curable ink onto a medium;
Emitting ultraviolet rays,
Diffusing the emitted ultraviolet light;
Irradiating the ultraviolet curable ink on the medium with the diffused ultraviolet rays to temporarily cure the ultraviolet curable ink;
A printing method characterized by having:
According to such a printing method, the UV ink is spread and smoothed (leveled), the gloss of the printed image is increased, and a desired image quality can be obtained.

  In the following embodiments, an ink jet printer (hereinafter also referred to as “printer 1”) will be described as an example of a printing apparatus.

=== Regarding Printer of One Embodiment ===
Hereinafter, a printer 1 as an embodiment of a printing apparatus according to the present invention will be described with reference to FIGS. 1, 2, 3A, and 3B. FIG. 1 is a block diagram illustrating a configuration of the printer 1. FIG. 2 is a schematic view around the head of the printer 1. 3A and 3B are cross-sectional views of the printer 1. 3A corresponds to the AA cross section of FIG. 2, and FIG. 3B corresponds to the BB cross section of FIG.

  The printer 1 of the present embodiment discharges ultraviolet curable ink (hereinafter also referred to as “UV ink”) that is cured by irradiation with ultraviolet rays (hereinafter also referred to as “UV”) onto a medium such as paper or film. Thus, the apparatus prints an image on a medium. 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. In the printer 1 of this embodiment, an image is printed using four colors of UV inks of cyan (C), magenta (M), yellow (Y), and black (K).

  As shown in FIG. 1, the printer 1 includes a transport unit 10, a carriage unit 20, a head unit 30, an irradiation unit 40, a detector group 50, and a controller 60. The printer 1 receives print data from a computer 110 that is an external device. The state of the printer 1 is monitored by the detector group 50, and the detector group 50 gives a detection result to the controller 60. The controller 60 controls each unit (the conveyance unit 10, the carriage unit 20, the head unit 30, and the irradiation unit 40) based on the print data received from the computer 110 and the detection result given from the detector group 50. To do.

  Hereinafter, each element of the printer 1 of the present embodiment will be described with reference to FIGS. 2, 3A, and 3B.

  The transport unit 10 is configured to transport a medium in a predetermined direction (hereinafter referred to as “transport direction”), and includes a feeding roller 11, a transport motor (not shown), a transport roller 13, and a platen 14. And a discharge roller 15. The feeding roller 11 is a roller for feeding the medium inserted into the insertion port into the printer. The transport roller 13 is a roller that transports the medium fed by the feed roller 11 to a printable area, and is driven by a transport motor. The platen 14 supports the medium being printed. The discharge roller 15 is a roller for discharging the medium to the outside of the printer, and is provided on the downstream side in the transport direction with respect to the printable region.

  The carriage unit 20 is for moving the head in a predetermined direction (hereinafter referred to as “movement direction”). This movement of the carriage unit 20 is also called scanning. As shown in FIGS. 2, 3A, and 3B, the carriage unit 20 includes a carriage 21 and a carriage motor (not shown). The carriage 21 detachably holds an ink cartridge that stores UV ink. The carriage 21 is reciprocated along the guide shaft 24 by a carriage motor while being supported by a guide shaft 24 that intersects a conveyance direction described later.

The head unit 30 is configured to eject UV ink onto a medium, and includes a head 31 having a plurality of nozzles. Since the head 31 is provided on the carriage 21, when the carriage 21 moves in the movement direction, the head 31 also moves in the movement direction. Then, the UV ink is intermittently ejected while the head 31 is moving in the moving direction, whereby a raster line along the moving direction is formed on the medium. In the following, in the movement of the head 31, the movement moving from one end side to the other end side in FIG. 2 is called forward movement, and the movement moving from the other end side to one end side is called backward movement. In the present embodiment, the UV ink is discharged during the forward movement period, but the UV ink is not discharged during the backward movement period.
The configuration of the head 31 will be described later.

  The irradiation unit 40 is configured to irradiate the UV ink discharged onto the medium with UV. The UV ink discharged onto the medium is cured by receiving the UV irradiation from the irradiation unit 40. The irradiation unit 40 of the present embodiment includes provisional curing irradiation units 42 a and 42 b and a main curing irradiation unit 43. The details of the provisional curing irradiation units 42a and 42b and the main curing irradiation unit 43 will be described later.

  The detector group 50 includes a linear encoder (not shown), a rotary encoder (not shown), a medium detection sensor 53, and an optical sensor 54. The linear encoder detects the position of the carriage 21 in the moving direction. The rotary encoder detects the rotation amount of the transport roller 13. The medium detection sensor 53 detects the position of the front end of the medium being fed. The optical sensor 54 detects the presence or absence of a medium by a light emitting unit and a light receiving unit attached to the carriage 21. The optical sensor 54 detects the position of the end of the medium while moving by the carriage 31, and detects the width of the medium. The optical sensor 54 detects the front end (the end on the downstream side in the transport direction, also referred to as the upper end) and the rear end (the end on the upstream side in the transport direction, also referred to as the lower end) depending on the situation. can do.

  The controller 60 is a control unit (control unit) for controlling the printer 1, and 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 1. 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.

  When performing printing, the controller 60 alternately repeats an ink ejection operation for intermittently ejecting UV ink from the head 31 moving in the movement direction and a conveyance operation for conveying the medium in the conveyance direction, as will be described later. An image composed of a plurality of ink droplets is printed on a medium.

<About the configuration of the head 31>
FIG. 4 is an explanatory diagram of an example of the configuration of the head 31, and the head 31 is viewed from below. A plurality of nozzles 32 configured to eject UV ink are provided on the lower surface of the head 31. The head 31 of the present embodiment has a plurality of nozzles 32 for each CMYK ink color. The plurality of nozzles 32 are arranged at a constant nozzle pitch along a direction (conveying direction) that intersects the moving direction of the carriage 21. Thus, the head 31 is formed with nozzle rows Nc, Nm, Ny, and Nk for four colors of CMYK.

  In the present embodiment, each nozzle 32 is provided with a piezo element (not shown) as a drive element that discharges UV ink from each nozzle 32. The piezo element is driven by a drive signal controlled by the controller 60 and ejects droplet-shaped UV ink from each nozzle 32.

<About temporary curing and main curing>
In the present embodiment, the UV ink is cured by irradiating the UV ink discharged onto the medium 46 with UV. In the printer 1 according to the present embodiment, the irradiation unit 40 emits UV, irradiates the UV ink on the medium with UV, and temporarily cures the UV ink, and the temporary curing irradiation units 42a and 42b emit UV. Is irradiated to the UV ink on the medium, and a main curing irradiation section 43 for main curing of the UV ink is provided, and two-stage curing is performed. Preliminary curing is a state in which the flow (spreading) of UV ink on the medium 46 is suppressed to some extent and curing is performed, and main curing is a state in which the UV ink on the medium 46 is completely cured. . The UV irradiation energy received per unit area (that is, the UV irradiation amount) is larger in the main curing than in the temporary curing. UV irradiation to such an extent that temporary curing is performed is also referred to as pinning irradiation.

  As shown in FIGS. 2 and 3B, the provisional curing irradiation units 42 a and 42 b are mounted on the carriage 21. The provisional curing irradiation unit 42 a is provided on one end side in the movement direction of the carriage 21, and the provisional curing irradiation unit 42 b is provided on the other end side in the movement direction of the carriage 21. Therefore, as the carriage 21 moves, the head 31 and the pre-curing irradiation units 42a and 42b move together in the movement direction. In other words, when the nozzle rows of each color of the head 31 reciprocate, the temporary curing irradiation units 42a and 42b reciprocate while maintaining the relative positions with respect to the nozzle rows of each color. At this time, the pre-curing irradiation units 42a and 42b emit UV and irradiate the UV ink on the medium with UV. Specifically, the temporary curing irradiation unit 42a emits UV during the forward movement, and the temporary curing irradiation unit 42b emits UV during the backward movement. As described above, the temporary curing is performed in the period during which the head 31 moves in the moving direction, that is, the same period as when the UV ink is ejected.

  The main curing irradiation section 43 is provided downstream of the head 31 in the transport direction. The size of the main curing irradiation unit 43 in the moving direction of the carriage 21 is larger than the width of the medium 46 to be printed. The main curing irradiation unit 43 emits UV and irradiates the UV ink on the medium 46 with UV. With this configuration, when the medium 46 carrying the UV ink formed by the ink ejection operation is transported to the bottom of the main curing irradiation unit 43 by the transportation operation, the medium 46 is irradiated with UV from the main curing irradiation unit 43. It has become.

  Further, the main curing may be performed with an irradiation amount equal to or higher than an irradiation amount that causes a necessary degree of curing when using the printed matter obtained by the printer according to the present embodiment. The effect of is at least not as great as the irradiation conditions for pre-curing.

  In the present embodiment, a light emitting diode (LED) is used as the light source of the pre-curing irradiation units 42a and 42b. Further, a lamp such as a metal halide lamp or a mercury lamp is used as the light source of the main curing irradiation unit 43.

<About diffusion member>
FIG. 5 is a diagram showing an example of the diffusing member according to the present invention. In the present embodiment, the diffusing member is a Fresnel lens 45.

  As described above, according to the present embodiment, when the nozzle rows of each color of the head 31 reciprocate, the temporary curing irradiation units 42a and 42b reciprocate while maintaining the relative positions with respect to the nozzle rows of each color. At this time, the pre-curing irradiation units 42a and 42b emit UV and irradiate the UV ink on the medium with UV.

  Further, in the printer 1 according to the present embodiment, the Fresnel lens 45 is provided as a diffusion member that diffuses the UV emitted by the pre-curing irradiation unit 42a. Although only the case of the pre-curing irradiation unit 42a is shown in FIG. 5, the printer 1 according to the present embodiment is also provided with a Fresnel lens that diffuses UV emitted from the pre-curing irradiation unit 42b.

  The Fresnel lens is an optical component having a configuration in which the lens is divided into concentric regions to reduce the thickness in order to realize the same optical properties as the concave-convex lens. The shape of the Fresnel lens is a thin flat plate. Further, by adopting such a configuration, the optical properties similar to those of the concave and convex lens can be realized with a small amount of material, so that the cost for the material can be suppressed and a lightweight optical component can be obtained.

  The Fresnel lens 45 of this embodiment is configured to diffuse UV. Since the Fresnel lens 45 has a thin flat plate shape, it can be easily provided in the printer 1 according to the present invention. Further, since the Fresnel lens 45 is lightweight, even when it is moved together with the carriage unit 20, the influence on the output of the carriage motor that drives the carriage unit 20 can be reduced.

  Considering the irradiation of the UV ink per unit area of the medium 46, when UV is diffused, the UV ink is slowly cured at low illuminance over time. Therefore, in such a case, the UV ink spreads and is smoothed (leveled), and the gloss of the printed image is increased. As described above, in the printer 1 of the present embodiment, a printed image with high gloss can be realized even when the irradiation amount is the same as that in the case where the UV emitted by the pre-curing irradiation unit 42 is not diffused.

<Printing procedure>
The controller 60 causes each unit of the printer 1 to perform the following processing when performing printing based on the print data received from the computer 110.

  First, the controller 60 rotates the feed roller 11 to feed the medium 46 to be printed to the transport roller 13. Next, the controller 60 rotates the transport roller 13 by driving a transport motor (not shown). When the transport roller 13 rotates with a predetermined rotation amount, the medium 46 is transported with a predetermined transport amount.

  When the medium 46 is transported to the lower part of the head 31, the controller 60 drives a carriage motor (not shown). As the carriage motor is driven, the carriage 21 moves in the moving direction. Further, as the carriage 21 moves, the head 31 and the pre-curing irradiation units 42a and 42b provided on the carriage 21 simultaneously move in the moving direction. Then, the controller 60 intermittently discharges UV ink from the head 31 while the head 31 is moving in the moving direction (that is, while moving forward). The UV ink is intermittently ejected onto the medium 46 to form a raster line in which a plurality of ink droplets are arranged in the moving direction.

  Further, the controller 60 is configured so that UV is emitted from the pre-curing irradiation unit 42a while the head 31 is moving forward, and while the head 31 is moving backward, the pre-curing irradiation unit 42b. The head unit 30 is controlled so that UV is emitted from the head unit 30.

  The controller 60 drives the transport motor every time the head 31 moves one reciprocating motion. The transport motor generates a driving force in the rotation direction according to the driving amount instructed by the controller 60. And a conveyance motor rotates the conveyance roller 13 using this drive force. As the transport roller 13 rotates by a predetermined rotation amount, the medium 46 is transported by a predetermined transport amount. That is, the conveyance amount of the medium 46 is determined according to the rotation amount of the conveyance roller 13. In this manner, the reciprocating movement of the head 31 and the conveying operation of the medium 46 are alternately repeated to form a plurality of raster lines on the medium 46.

  Then, the controller 60 causes the main curing irradiation unit 43 to emit UV, and causes the UV irradiation toward the medium 46 passing under the main curing irradiation unit 43 by the transport operation. By this UV irradiation, the UV ink on the medium 46 is completely cured and fixed to the medium.

The medium 46 that has been printed is discharged from the printer 1 by the discharge roller 15 that rotates in synchronization with the transport roller 13.
Thus, an image is printed on the medium 46.

=== 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.

  In the above embodiment, the printing apparatus is embodied as an ink jet printer. However, the present invention is not limited to this, and the present invention can also be applied to other printing apparatuses.

<About the printer>
In the above-described embodiment, the serial printer is described as the printer, but the present invention is not limited to this. For example, the present invention can be implemented in a line printer.

<About nozzle>
In the above-described embodiment, ink is ejected using a piezoelectric element (piezo element). However, the method for discharging the liquid is not limited to this. For example, other methods such as a method of generating bubbles in the nozzle by heat may be used.

<About the irradiation part for temporary curing>
In the embodiment in the case of the serial printer described above, the provisional curing irradiation units 42 a and 42 b are provided at both ends of the carriage 21 in the moving direction. However, for example, when the printer is configured such that ink is ejected only during the forward movement of the head, the pre-curing irradiation units 42a and 42b are more than the position in the moving direction of the head 31 when ejecting ink. It may be provided only on the rear side. For example, in the present embodiment, only the temporary curing irradiation section 42a may be used. In such a case, UV may be irradiated only during the forward movement period, or UV may be irradiated during both forward and backward movement periods.

<About diffusion member>
In the above-described embodiment, the Fresnel lens 45 is used as a diffusion member that diffuses the UV emitted from the pre-curing irradiation units 42a and 42b. However, the diffusing member is not limited to the Fresnel lens, and may be any member that diffuses the UV emitted by the pre-curing irradiation portions 42a and 42b. For example, the reflecting plate 47 shown in FIG. Good.
The reflecting plate 47 is an optical component configured to reflect UV. According to this embodiment, the reflection plate 47 reflects UV, and the reflected UV is diffused and irradiated onto the medium.

1 printer, 10 transport unit, 11 feeding roller,
13 transport roller, 14 platen, 15 discharge roller,
20 carriage unit, 21 carriage,
30 head units, 31 heads, 32 nozzles,
40 irradiation unit, 42a, 42b pre-curing irradiation unit,
43 irradiation part for main curing, 45 Fresnel lens, 46 medium, 47 reflector,
50 detector groups, 53 medium detection sensors, 54 optical sensors,
60 controller, 61 interface, 62 CPU,
63 memory, 64 unit control circuit,
110 computer

Claims (4)

A head for discharging ultraviolet curable ink onto a medium;
A temporary curing irradiation unit that emits ultraviolet rays, irradiates the ultraviolet curable ink on the medium with the ultraviolet rays, and temporarily cures the ultraviolet curable ink;
A diffusion member that diffuses the ultraviolet rays emitted by the pre-curing irradiation section;
A printing apparatus comprising: The printing apparatus according to claim 1,
The printing apparatus, wherein the diffusing member is a Fresnel lens. The printing apparatus according to claim 1,
The diffusing member is a reflecting plate. Discharging ultraviolet curable ink onto a medium;
Emitting ultraviolet rays,
Diffusing the emitted ultraviolet light;
Irradiating the ultraviolet curable ink on the medium with the diffused ultraviolet rays to temporarily cure the ultraviolet curable ink;
A printing method characterized by comprising:

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