Patent Publication Number: US-2015062237-A1

Title: Printer, printer control method, and wettability enhancement treatment device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Japanese Patent Application No. 2013-183802 filed on Sep. 5, 2013. The entire disclosure of Japanese Patent Application No. 2013-183802 is hereby incorporated herein by reference. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a printer, a printer control method, and a wettability enhancement treatment device capable of performing wettability enhancement treatment such as corona treatment, plasma treatment, frame treatment or the like, for example. 
     2. Related Art 
     From the past, known are inkjet recording devices equipped with ink heads for discharging ink on the ink-imparted surface of a base material, and a wettability enhancement treatment device for performing wettability enhancement treatment such as corona treatment or the like that enhances wettability in relation to the ink on the ink-imparted surface of the base material (see JP-A-2008-207528 (Patent Document 1), for example). 
     SUMMARY 
     However, with this kind of printer, when corona treatment was performed as the wettability enhancement treatment on the printing surface of the print medium, ozone was generated. Because of that, it is preferable to not perform wettability enhancement treatment when the original wettability is high and it is not necessary to enhance wettability. However, in the past, there was no printer based on the concept of performing wettability enhancement treatment according to the difference in wettability. 
     An object of the present invention is to provide a printer, a printer control method, and a wettability enhancement treatment device that is able to perform wettability enhancement treatment as necessary. 
     The printer of the present invention is equipped with a discharge unit that is configured to discharge ink on a printing surface of a print medium, a wettability enhancement treatment unit that, before discharging of the ink by the discharge unit, is configured to be set to a treating state in which wettability enhancement treatment that enhances wettability in relation to the ink is performed on the printing surface, or a non-treating state in which the wettability enhancement treatment is not performed, a wettability information acquisition unit that is configured to acquire wettability information related to wettability of the printing surface for which the wettability enhancement treatment is not performed, and a control unit that is configured to set the wettability enhancement treatment unit to the treating state when the acquired wettability information is designated information relating to low wettability, and is configured to set the wettability enhancement treatment unit to the non-treating state when the acquired wettability information is not the designated information. 
     The printer control method for the printer of the present invention is a printer control method for a printer having a discharge unit that is configured to discharge ink on a printing surface of a print medium, and a wettability enhancement treatment unit that, before discharging of the ink by the discharge unit, is configured to be set to either a treating state in which wettability enhancement treatment that enhances wettability in relation to the ink is performed on the printing surface, or a non-treating state in which the wettability enhancement treatment is not performed, the printer control method including acquiring wettability information related to the wettability of the printing surface for which the wettability enhancement treatment has not been performed, and setting the wettability enhancement treatment unit to the treating state when the acquired wettability information is designated information related to low wettability, and setting the wettability enhancement treatment unit to the non-treating state when the acquired wettability information is not the designated information. 
     With this constitution, by setting the wettability enhancement treatment unit to the treating state when the acquired wettability information is designated information relating to low wettability, it is possible to enhance the wettability of the printing surface and to discharge the ink on the printing surface for which the wettability has been enhanced. On the other hand, by setting the wettability enhancement treatment unit to the non-treating state when the acquired wettability information is not the designated information relating to low wettability, since wettability enhancement treatment is not performed, it is possible to inhibit an increase in energy consumption volume, for example, power consumption volume. In this way, it is possible to perform wettability enhancement treatment as necessary. 
     With the aforementioned printer, the wettability information acquisition unit is further configured to acquire a material of the print medium as the wettability information, and it is preferable that when the acquired material of the print medium is the designated low wettability material of low wettability, the control unit is configured to set the wettability enhancement treatment unit to the treating state, and when the acquired material of the print medium is not the designated low wettability material, the control unit is configured to set the wettability enhancement treatment unit to the non-treating state. 
     With this constitution, the wettability enhancement treatment is performed when the acquired material of the print medium is a designated material for which the wettability in relation to the ink is low, so it is possible to increase the wettability of the printing surface. On the other hand, when the acquired material of the print medium is not the designated material for which the wettability in relation to the ink is low, the wettability enhancement treatment is not performed. Therefore, even when print mediums of different materials are used, it is possible to perform the wettability enhancement treatment as necessary. 
     In this case, the wettability enhancement treatment unit is preferably configured to perform corona treatment as the wettability enhancement treatment. 
     In this case, the wettability information acquisition unit has an imaging unit that is configured to image a discharge pattern formed by the discharge unit discharging the ink on the printing surface for which wettability enhancement treatment has not been performed. The wettability information acquisition unit is further configured to acquire as the wettability information the imaging result of the discharge pattern. Preferably when the acquired imaging result indicates that the wettability is low, the control unit is further configured to set the wettability enhancement treatment unit to the treating state, and when the acquired imaging result indicates that the wettability is high, the control unit is further configured to set the wettability enhancement treatment unit to the non-treating state. 
     With this constitution, the imaging result of the discharge pattern formed by discharging the ink on the printing surface are acquired as the wettability information. Because of this, it is possible to obtain the wettability information according to the actual wettability. 
     For example, when the discharge unit forms a ruled line type line as the discharge pattern, and the control unit finds the thickness of the line from the imaging result and the line thickness is smaller than a designated value, it sets the wettability enhancement treatment unit to the treating state. Also, when the discharge unit forms a flat image as the discharge pattern, and the control unit finds the dispersion value of the image density from the imaging result, and the dispersion value of the image density is greater than a designated value, it is also possible to set the wettability enhancement treatment unit to the treating state. 
     In this case, the discharge unit is preferably provided on the device main unit, and the wettability enhancement treatment unit is detachable with respect to the device main unit. 
     With this constitution, for example when it is not necessary to perform corona treatment such as when always using a print medium that originally has high wettability, it is also possible to use this with the wettability enhancement treatment unit removed. Also, the overall printer size becomes smaller by the amount not taken up by the wettability enhancement treatment unit, so it is possible to install in a relatively small space. 
     The wettability enhancement treatment device of the present invention is equipped with a wettability enhancement treatment unit that is configured to be set to a treating state in which wettability enhancement treatment that enhances wettability in relation to ink is performed on a printing surface of a print medium, or a non-treating state in which the wettability enhancement treatment is not performed, a wettability information acquisition unit that is configured to acquire wettability information related to the wettability of the printing surface for which the wettability enhancement treatment has not been performed, and a control unit that is configured to set the wettability enhancement treatment unit to the treating state when the acquired wettability information is designated information related to low wettability, and is configured to set the wettability enhancement treatment unit to the non-treating state when the acquired wettability information is not the designated information. 
     With this constitution, by setting the wettability enhancement treatment unit to the treating state when the acquired wettability information is designated information related to low wettability, it is possible to enhance the wettability of the printing surface. On the other hand, by setting the wettability enhancement treatment unit to the non-treating state when the acquired wettability information is not the designated information related to low wettability, since the wettability enhancement treatment is not performed, it is possible to suppress an increase in the volume of power consumed. In this way, it is possible to perform wettability enhancement treatment as necessary. 
     In this case, it is preferable for the wettability enhancement treatment device to be attachable to a printer having a discharge unit that is configured to discharge the ink on the printing surface such that the wettability enhancement treatment is performed before discharging of the ink by the discharge unit. 
     With this constitution, it is possible to attach the wettability enhancement treatment device to the printer not equipped with the wettability enhancement treatment unit. By doing this, it is possible to perform the wettability enhancement treatment as necessary even with that kind of printer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring now to the attached drawings which form a part of this original disclosure: 
         FIG. 1  is a configuration diagram of a printer of one embodiment of the present invention; 
         FIG. 2  is a block diagram of the printer; 
         FIG. 3  is a flow chart showing the control of a corona treater with the printer; and 
         FIG. 4  is a flow chart showing the control of a high pressure mercury lamp with the printer. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Following, we will describe the printer of one embodiment of the present invention while referring to the attached drawings. This printer performs printing using the inkjet method on a printing medium using UV ink (ultraviolet curing type ink). The printer is connected so as to be able to communicate with a host computer which is an external device, and performs printing based on the printing data sent from the host computer. The print medium is constituted by a long shaped sheet material, and various materials can be used such as paper, film or the like as described later. 
     As shown in  FIG. 1 , a printer  1  is equipped with a device main unit  2 , a corona treatment unit  3  provided on one side of the device main unit  2 , and a strong irradiation unit  4  provided on the other side of the device main unit  2 . 
     The device main unit  2  is equipped with a supply reel  5  provided nearer to the corona treatment unit  3 , a take-up reel  6  provided nearer to the strong irradiation unit  4 , a rotating drum  7  provided roughly in the middle of a feed path, a discharge unit  8  and an LED lamp  9  (Light Emitting Diode) provided so as to face opposite the circumference surface of the rotating drum  7 , and a main unit cover  11  that accommodates these. On the device main unit  2 , provided are a first main unit side coupling unit  31  that couples with a processing unit side coupling unit  33  (described later) of the corona treatment unit  3 , and a second main unit side coupling unit  32  that couples with an irradiating unit side coupling unit  35  (described later) of the strong irradiation unit  4 . Also, a control circuit substrate (not illustrated) constituting the control unit  28  described later is mounted on the device main unit  2 . 
     The supply reel  5 , the take-up reel  6 , and the rotating drum  7 , together with an upstream side folding roller  17  and a downstream side folding roller  22  described later, constitute a feed unit  12  that feeds a print medium S using a roll-to-roll method. 
     The supply reel  5  is rotated by a supply motor (not illustrated), and supplies the print medium S wound into roll form to the upstream side folding roller  17 . The take-up reel  6  is rotated by a take-up motor (not illustrated), and takes-up the print medium S fed via the downstream side folding roller  22 . The rotating drum  7  is a cylinder shaped drum supported so as to be able to rotate by a support mechanism (not illustrated), and the print medium S fed from the upstream side folding roller  17  to the downstream side folding roller  22  is supported from the back surface side, in other words, the side opposite to the printing surface Sa. The rotating drum  7  receives friction force with the print medium S, and does driven rotation in the feed direction of the print medium  5 , in other words, clockwise in  FIG. 1 . 
     The discharge unit  8  has a plurality of (e.g. five) inkjet heads  14  provided in radiating form in relation to the rotating drum  7 . Each inkjet head  14  discharges UV ink onto the printing surface Sa of the print medium S fed at the circumference surface of the rotation drum  7 . Of the five inkjet heads  14 , four inkjet heads  14  on the feed direction upstream side discharge UV ink of mutually different colors (e.g. cyan, magenta, yellow, black), and the furthest downstream side inkjet head  14  discharges UV ink that does not contain a coloring material, in other words, clear ink. After a color image is formed on the printing surface Sa of the print medium S by the four upstream side inkjet heads  14 , the clear ink is discharged by the furthest downstream side inkjet head  14  to give a gloss to the color image. 
     The LED lamp  9  (first light irradiator) and a high pressure mercury lamp  23  (second light irradiator) described later constitute an ultraviolet irradiation unit  15 . As described later, the ultraviolet irradiation unit  15  is settable to a first mode of irradiating ultraviolet rays only from the LED lamp  9  on the print medium S on which UV ink has been discharged, or a second mode of irradiating ultraviolet rays from both the LED lamp  9  and the high pressure mercury lamp  23 . With the second mode, it is also possible to not have ultraviolet rays irradiated from the LED lamp  9 , having ultraviolet rays irradiated only from the high pressure mercury lamp. 
     Also, in addition to the LED lamp  9  and the high pressure mercury lamp  23 , it is also possible to provide a temporary curing irradiator for irradiating ultraviolet rays for temporary curing proximate to the feed direction downstream side of each inkjet head  14 . 
     The LED lamp  9  is provided further to the feed direction downstream side than the discharge unit  8 , and irradiates ultraviolet rays (first light) of a single wavelength (e.g. 395 nm). By the LED lamp  9  irradiating the first light on the printing surface Sa of the print medium S on which UV ink has been discharged, the UV ink is cured on the printing surface Sa, and is fixed or adhered to the printing surface Sa. 
     On the main unit cover  11  is connected a main unit duct  16  that allows the heat of reaction generated when the UV ink is cured to escape, and is also for recovering UV ink that became mist when discharged from the inkjet head  14 . 
     The corona treatment unit  3  has an upstream side folding roller  17 , a corona treater  18  provided so as to be along the circumference surface of the upstream side folding roller  17 , and a corona unit cover  19  in which these are accommodated. Provided on the corona treatment unit  3  are a processing unit side coupling unit  33  coupled with the aforementioned first main unit side coupling unit  31 , and a processing unit side cable connector  34  for electrically connecting with the aforementioned control circuit substrate. 
     The upstream side folding roller  17  changes the feed path so that the print medium S supplied from the supply reel  5  is fed toward the rotating drum  7 . 
     The corona treater  18  selectively performs corona treatment (corona irradiation) on the printing surface Sa of the print medium S fed along the circumference surface of the upstream side folding roller  17 . Specifically, the corona treater  18  is settable to the treating state (ON) for performing corona treatment on the printing surface Sa of the print medium S, and the non-treating state (OFF) that does not perform corona treatment, and the control unit  28  described later (see  FIG. 2 ) controls the corona treater  18  to switch between the treating state and the non-treating state according to the material of the print medium S. By corona treatment being performed on the printing surface Sa of the print medium S by the corona treater  18 , the wettability of the printing surface Sa in relation to UV ink is enhanced. 
     A corona unit duct  21  is connected to the corona unit cover  19  to exhaust ozone generated by the corona treatment. 
     Also, the corona treatment unit  3  is constituted to be detachable in relation to the device main unit  2  by the processing unit side coupling unit  33  being coupled to the first main unit side coupling unit  31 . Because of this, when it is not necessary to perform corona treatment such as when always using a print medium S that originally has high wettability, it is also possible to use this with the corona treatment unit  3  removed. Also, the overall size of the printer  1  is smaller by the amount not taken up by the corona treatment unit  3 , so it is possible to install in a relatively small space. In this case, the feed path of the print medium S reaching from the supply reel  5  to the rotating drum  7  is changed as appropriate. 
     The strong irradiation unit  4  has the downstream side folding roller  22 , the high pressure mercury lamp  23  provided further to the feed direction upstream side than the downstream side folding roller  22 , and an irradiation unit cover  24  in which these are accommodated. Provided on the strong irradiation unit  4  are the irradiation unit side coupling unit  35  for coupling with the aforementioned second main unit side coupling unit  32  and an irradiation unit side cable connector  36  for electrically connecting with the aforementioned control circuit substrate. 
     The downstream side folding roller  22  changes the feed path so that the print medium S fed from the rotating drum  7  is fed toward the take-up reel  6 . 
     The high pressure mercury lamp  23  is provided further to the feed direction downstream side than the aforementioned LED lamp  9 , and irradiates ultraviolet rays (second light) having a broader wavelength spectrum and having higher energy than the LED lamp  9 . Specifically, the second light irradiated by the high pressure mercury lamp  23  has higher curing properties for curing the UV ink than the first light irradiated by the LED lamp  9 . 
     The high pressure mercury lamp  23  selectively irradiates the second light on the printing surface Sa of the print medium S fed from the device main unit  2 . Specifically, the high pressure mercury lamp  23  is settable to the irradiating state (ON) that irradiates the second light on the printing surface Sa on which UV ink has been discharged, and the non-irradiating state (OFF) that does not irradiate the second light, and the control unit  28  described later controls switching between the high pressure mercury lamp  23  irradiating state and the non-irradiating state according to the material of the print medium S or the like. 
     An irradiating unit duct  25  is provided on the irradiating unit cover  24  to exhaust ozone generated by ultraviolet irradiation. 
     Also, the strong irradiation unit  4  is constituted to be detachable with the device main unit  2  by the irradiating unit side coupling unit  35  coupling with the second main unit side coupling unit  32 . Because of this, when irradiation of the second light by the high pressure mercury lamp  23  is not necessary, it is also possible to use this with the strong irradiation unit  4  removed. Also, the overall size of the printer  1  is smaller by the amount not taken up by the strong irradiation unit  4 , so it is also possible to install in a relatively small space. In this case, the feed path of the print medium S from the rotating drum  7  to the take-up reel  6  is changed as appropriate. 
     To summarize the above, with the printer  1 , the corona treater  18  performs corona treatment on the printing surface Sa of the print medium S supplied from the supply reel  5  according to the material of the print medium S. The discharge unit  8  discharges UV ink on the printing surface Sa of the print medium S fed from the corona treatment unit  3 . Also, the LED lamp  9  irradiates the first light on the print medium S on which UV ink has been discharged. Furthermore, the high pressure mercury lamp  23  irradiates the second light on the print medium S fed from the device main unit  2  according to the material of the print medium S or the like. The take-up reel  6  winds up the already printed part of the print medium S for which a series of printing processes has been implemented in this way. 
     We will describe the control system of the printer  1  while referring to  FIG. 2 . The printer  1  is equipped with a display unit  26 , an input unit  27 , and the control unit  28 . Also, the operation of the printer  1  is controlled by a host computer  29  connected to be able to communicate. 
     The display unit  26  is constituted by a liquid crystal display or the like, for example, and displays a menu screen, error message or the like to an operator. The input unit  27  has selection buttons, setting buttons and the like, and receives input of various types of information from the operator. By the operator operating the input unit  27  while checking the display unit  26 , the print setting screen is opened from the menu screen, and various types of information are input such as the material of the print medium S, the size of the print medium S, the type of UV ink or the like. 
     This information can also be input using an input unit such as a keyboard, mouse or the like provided on the host computer  29 . 
     The control unit  28  is constituted from a CPU (Central Processing Unit), memory and the like. The control unit  28  controls each part of the printer  1  according to various types of information input from the input unit  27 , or print data and various types of commands received from the host computer  29  or the like. 
     Here, we will give a detailed description regarding control of the corona treater  18  by the control unit  28 . The control unit  28  controls whether to have the corona treater  18  set to the treating state or the non-treating state according to the material of the print medium S. 
     The material of the print medium S used with the printer  1  is roughly divided into paper and film. Paper includes cast-coated paper, semi-gloss paper and the like, and film includes PP film (polypropylene), PE film (polyethylene terephthalate), PE film (polyethylene) and the like. 
     Of these materials of the print medium S, there are many items for which the wettability of the printing surface Sa in relation to UV ink is low if corona treatment by the corona treater  18  is not performed for the cast-coated paper, semi-gloss paper, and PP film. When the wettability of the printing surface Sa is low, the UV ink discharged from the inkjet head  14  does not easily wet and spread on the printing surface Sa. Because of this, for example when printing a flat image, there is the risk of a patchy pattern occurring. Meanwhile, for PET film and PE film, even when corona treatment by the corona treater  18  is not performed, there are many items for which the wettability of the printing surface Sa in relation to UV ink is high. 
     In light of that, when the material of the input print medium S is a designated material of low wettability in relation to UV ink, specifically, when it is a designated low wettability material, the control unit  28  performs control to set the corona treater  18  to the treating state, and when it is not a designated low wettability material, sets the corona treater  18  to the non-treating state. With this embodiment, of the various materials of the print medium S noted above, cast-coated paper, semi-gloss paper, and PP film are designated low wettability materials. 
     As shown in  FIG. 3 , the control unit  28  judges whether or not the material of the print medium S input from the input unit  27  by the operator is a designated low wettability material, specifically, whether it is any of cast-coated paper, semi-gloss paper, or PP film (S 1 ). 
     When the control unit  28  determines that the material of the input print medium S is for example cast-coated paper, and that the material of the print medium S is a designated low wettability material (S 1 : Yes), it sets the corona treater  18  to the treating state (S 2 ). 
     On the other hand, when the control unit  28  determines that the material of the input print medium S is for example PET film, and that the material of the print medium S is not a designated low wettability material (S 1 : No), it sets the corona treater  18  to the non-treating state (S 3 ). 
     In this way, when the material of the acquired print medium S is a designated low wettability material with low wettability to UV ink as is the case with cast-coated paper, the printer  1  performs corona treatment, so it is possible to enhance the wettability of the printing surface Sa, and it is possible to discharge ink on the printing surface Sa for which wettability has been enhanced. On the other hand, when the material of the acquired print medium S is not a designated low wettability material for which the wettability to UV ink is low as with PET film, corona treatment is not performed, so it is possible to inhibit an increase in the power consumption volume. Therefore, even when using print media S of different materials, it is possible to perform wettability enhancement treatment as necessary. 
     With this embodiment, the control unit  28  has cast-coated paper, semi-gloss paper, and PP film as designated low wettability materials for which the wettability to UV ink is low, but it is possible to set any material to be the designated low wettability material. Specifically, it is possible to study the wettability of the printing surface Sa to UV ink for each material of the print medium S in advance, and as a result, to set materials for which wettability was low as the designated low wettability material. 
     With this embodiment, the printer  1  acquires the material of the print medium S by the operator inputting from the input unit  27 , but the constitution for acquiring the print medium S is not limited to this. For example, it is also possible to provide an identifier indicating that material, for example a two dimensional code, on the print medium S, and to acquire the material of the print medium S by the printer  1  reading the identifier using a two dimensional code reader, for example. 
     Also, with this embodiment, as the wettability information relating to the wettability of the printing surface Sa, the material of the print medium S was used, but the wettability information is not limited to this. For example, it is also possible to use the type of UV ink as the wettability information. In this case, when the type of input UV ink is a designated type with low wettability, the control unit  28  sets the corona treater  18  to the treating state. Also, it is possible to use both the material of the print medium S and the type of UV ink as the wettability information. In this case, when the material of the input print medium S and the type of UV ink are a designated combination of low wettability, the control unit  28  sets the corona treater  18  to the treating state. Also, it is possible to use a numerical value indicating the wettability of the printing surface Sa to the UV ink, for example the contact angle, as the wettability information. In this case, when the input contact angle exceeds a designated value, for example, the control unit  28  sets the corona treater  18  to the treating state. 
     Furthermore, it is also possible to use the discharge pattern imaging results as the wettability information. Specifically, it is also possible to provide a scanner (imaging unit) further to the feed direction downstream side than the discharge unit  8 , and using that scanner, to image the discharge pattern formed by the discharge unit  8  discharging UV ink on the printing surface Sa for which corona treatment has not been performed, and to use those imaging results as the wettability information. Also, when the acquired imaging results indicate that the wettability is low, the control unit  28  sets the corona treater  18  to the treating state, and when it indicates that the wettability is high, it sets the corona treater  18  to the non-treating state. 
     For example, the discharge unit  8  forms a ruled line as the discharge pattern, and when the line thickness is found from those imaging results and the line thickness is smaller than a designated value, said another way, when the line is thin, the control unit  28  sets the corona treater  18  to the treating state. It is also possible to constitute this so that when the discharge unit  8  forms a flat image as the discharge pattern, when the image density dispersion value is found from those results, and the image density dispersion value is greater than a designated value, said another way, when a patchy pattern occurs, the control unit  28  sets the corona treater  18  to the treating state. Here, the image density dispersion value means the variation state of the image density for each pixel within a fixed surface area. In this way, by using the discharge pattern imaging results as the wettability information, it is possible to obtain wettability information according to the actual wettability. 
     With this embodiment, as the wettability enhancement treatment unit (wettability enhancement treatment device) for enhancing the wettability of the printing surface Sa of the print medium S, the corona treater  18  was used, but this is not limited to this, and for example it is also possible to use other treatment devices for enhancing wettability, such as a plasma treatment device, frame treatment device or the like, for example. However, the corona treater  18  is preferable in light of being low cost and having low energy consumption compared to other treatment devices. 
     Following, we will give a detailed description regarding the ultraviolet irradiation unit  15  by the control unit  28 . The control unit  28  controls whether to set the high pressure mercury lamp  23  to an irradiating state or a non-irradiating state according to the material of the print medium S and the print duty of the clear ink. By doing this, the control unit  28  controls switching of the ultraviolet irradiation unit  15  between the first mode and the second mode. 
     Of the various materials of the print medium S noted above, for cast-coated paper, semi-gloss paper, and PP film, with only the first light being irradiated by the LED lamp  9  on the printing surface Sa on which UV ink is discharged, in many cases, it was not possible to obtain sufficient adhesiveness between the cured UV ink and the printing surface Sa. When it is not possible to obtain sufficient adhesiveness between the cured UV ink and the printing surface Sa, for example, when tape that is adhered to a surface on which cured UV ink, or said another way, a printed image is formed by fixing the UV ink on the print medium S, is peeled, it is easier for the UV ink on that part to peel off together. On the other hand, for PET film and PE film, in many cases, sufficient adhesiveness was obtained between the cured UV ink and the printing surface Sa with only the irradiation of the first light by the LED lamp  9 . 
     Also, when performing high printing duty printing using clear ink that does not contain pigment, when the residual volume of polymerization initiator becomes greater because of insufficient ultraviolet irradiation, since the polymerization initiator itself has color tone, the b* of the cured clear ink, said another way, the printed image formed by fixing of clear ink on the print medium S, becomes large, specifically, there is a trend for the yellow tone to increase (turn yellow). 
     In light of that, when the material of the input print medium S is a designated material of low ink adhesiveness, specifically, when it is a designated low adhesiveness material, the control unit  28  performs control so as to set the high pressure mercury lamp  23  to the irradiating state, and when the clear ink print duty exceeds a designated value, it sets the high pressure mercury lamp  23  to the irradiating state. Ink adhesiveness means the adhesiveness of the UV ink and the print medium S when the UV ink is cured using the first light from the LED lamp  9 . With this embodiment, of the various media of the print medium S noted above, cast-coated paper, semi-gloss paper and PP film are set as the designated low adhesiveness materials. 
     As shown in  FIG. 4 , the control unit  28  determines whether or not the material of the print medium S input from the input unit  27  by the operator is the designated low adhesiveness material, specifically, whether or not it is any of cast-coated paper, semi-gloss paper, and PP film (S 11 ). The material of the print medium S can also be acquired by reading an identifier provided with the print medium S using a reading device as described above. 
     When the control unit  28  determines that the material of the print medium S is for example cast-coated paper, and the material of the print medium S is a designated low adhesiveness material (S 11 : Yes), it sets the high pressure mercury lamp  23  to the irradiating state (S 12 ). 
     On the other hand, when the material of the input print medium S is for example PET film, the control unit  28  determines that the material of the print medium S is not the designated low adhesiveness material (S 11 : No), and subsequently, determines whether or not the print duty of the clear ink exceeds a designated value (e.g. 60%) (S 13 ). The clear ink print duty can be acquired from the clear ink print data or the like. 
     When the control unit  28  determines that the clear ink print duty exceeds a designated value (S 13 : Yes), it sets the high pressure mercury lamp  23  to the irradiating state (S 12 ). On the other hand, when the control unit  28  determines that the clear ink print duty does not exceed a designated value (S 13 : No), it sets the high pressure mercury lamp  23  to the non-irradiating state (S 14 ). 
     In this way, when the material of the print medium S is a designated low adhesiveness material with low ink adhesiveness such as with cast-coated paper, the printer  1  irradiates the second light using the high pressure mercury lamp  23 , so it is possible to increase the adhesiveness of the cured UV ink and the print medium S. Also, even when the material of the print medium S is not the designated low adhesiveness material, when the clear ink print duty exceeds a designated value, the second light is irradiated by the high pressure mercury lamp  23 . By doing this, the reaction volume of the polymerization initiator contained in the clear ink increases, so it is possible to reduce the residual volume of the polymerization initiator, the b* of the cured clear ink becomes smaller, and it is possible to improve the yellowing level. On the other hand, when the material of the print medium S is not the designated low adhesiveness material with low ink adhesiveness such as with PET film, and the clear ink print duty does not exceed a designated value, by not having the second light irradiated by the high pressure mercury lamp  23 , it is possible to suppress an increase in the power consumption volume by the high pressure mercury lamp  23 . Therefore, it is possible to irradiate the second light using the high pressure mercury lamp  23  as necessary. 
     With this embodiment, the control unit  28  uses cast-coated paper, semi-gloss paper, and PP film as the designated low adhesiveness material with low ink adhesiveness, but it is possible to set any material as the designated low adhesiveness material. Specifically, it is possible to study in advance the ink adhesiveness of the UV ink and the print medium S when the UV ink is cured using the first light from the LED lamp  9  for each material of the print medium S, and as a result, to set the material for which the ink adhesiveness was low as the designated low adhesiveness material. The ink adhesiveness can be measured using the UV ink curing rate, for example, specifically, the residual rate of light polymerizable compounds contained in the UV ink. The lower the residual rate of the light polymerizable compounds, the higher the curing rate of the UV ink. 
     With this embodiment, the designated low wettability material and the designated low adhesiveness material are the same, but of course it is not necessary to have these be the same. 
     With this embodiment, even if the material of the print medium S is not the designated low adhesiveness material, when the clear ink print duty exceeds a designated value, the second light was made to be irradiated by the high pressure mercury lamp  23 , but when yellowing of the clear ink is not that much of a problem, when the material of the print medium S is not the designated low adhesiveness material, regardless of the clear ink print duty value, it is possible to have the second light irradiated by the high pressure mercury lamp  23 . By doing this, it is possible to further suppress an increase in the power consumption volume by the high pressure mercury lamp  23 . 
     With this embodiment, the ultraviolet irradiation unit  15  is constituted by the LED lamp  9  that irradiates the first light, and the high pressure mercury lamp  23  that irradiates the second light that has stronger curing properties than the first light, but as long as it is an item that irradiates ultraviolet rays of equivalent curing properties to these, it is also possible to use other ultraviolet irradiators. Furthermore, as long as it is an ultraviolet irradiator capable of selective irradiation of ultraviolet rays of the same curing properties as the first light and ultraviolet rays of the same curing properties of the second light, it is possible to constitute the ultraviolet irradiation unit  15  using a single ultraviolet irradiator. 
     As described above, with the printer  1  of this embodiment, when the acquired wettability information is designated information relating to low wettability, by having the corona treater  18  be set to the treating state, it is possible to enhance the wettability of the printing surface Sa, and possible to discharge UV ink on the printer surface Sa with improved wettability. On the other hand, when the acquired wettability information is not the designated information related to low wettability, by setting the corona treater  18  to the non-treating state, the wettability enhancement treatment is not performed, so it is possible to suppress an increase in the power consumption volume. In this way, it is possible to perform wettability enhancement treatment as necessary. 
     It is also possible to attach the corona treatment device equipped with the aforementioned corona treater  18 , the input unit  27 , and the control unit  28  to the printer equipped with the discharge unit  8 . In this case, this is attached so as to perform corona treatment ahead of discharging of ink by the discharge unit  8 . By doing this, it is possible to constitute the same kind of printer as the printer  1  of this embodiment. 
     Also, with this embodiment, UV ink was used, but other photo curable inks can also be used, and it is possible to use other inks such as water based ink, oil based ink or the like. Furthermore, with this embodiment, the discharge unit  8  was constituted using inkjet heads  14 , but it is also possible to have an item that discharges UV ink using another method. 
     General Interpretation of Terms 
     In understanding the scope of the present invention, the term “comprising” and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. The foregoing also applies to words having similar meanings such as the terms, “including”, “having” and their derivatives. Also, the terms “part,” “section,” “portion,” “member” or “element” when used in the singular can have the dual meaning of a single part or a plurality of parts. Finally, terms of degree such as “substantially”, “about” and “approximately” as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. For example, these terms can be construed as including a deviation of at least ±5% of the modified term if this deviation would not negate the meaning of the word it modifies. 
     While only a selected embodiment has been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. Furthermore, the foregoing descriptions of the embodiment according to the present invention are provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.