Patent Publication Number: US-2009219369-A1

Title: Ink jet recording apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 61/032,366, filed Feb. 28, 2008, No. 61/040,899, filed Mar. 31, 2008. 
    
    
     TECHNICAL FIELD 
     The present invention relates to an ink jet recording apparatus which ejects aqueous ink from an ink jet head to form an image on a paper. 
     BACKGROUND 
     Recently, an ink jet recording apparatus in which an aqueous ink is used can form a high quality of image on a plain paper. Since running cost is low and the apparatus is safe and quiet, the ink jet recording apparatus becomes common practice for home or official use. The ink jet recording apparatus can record the image with high density at high speed. Further, the ink jet recording apparatus adopts a non-impact system, so that noises are little. Moreover, the ink jet recording apparatus has an advantage that a color image is easily recorded by using multicolored inks. 
     A paper to be recorded by the ink jet recording apparatus gets wet by the ink. When the ink jet recording apparatus performs a high quality recording on the paper, the paper is subjected to a heated-air drying. 
     On the paper, a phenomenon as referred to as a rippling cockling or a curl occurs due to moisture in ink. Especially, a cellulose fiber is likely to be swollen or untied in the plain paper. 
     In JP-A-10-217572, a configuration is disclosed in which the paper is heated from the rear surface thereof through a guide having a mesh structure, a distance between a heater and the paper is shorten, and heat of the heater is directly transferred to the paper. According to the configuration disclosed in JP-A-10-217572, since the vapor generated from the paper is removed through the mesh, a difference in dry condition between both sides of the paper disappears, and the curl can be reduced, so that a sufficient heating effect is exhibited. 
     Further, in JP-A-10-217572, a configuration is disclosed in which a heater which heats a recording area of the paper and a guide member having a mesh structure which diffuses vapor generated from the paper are provided on a carrying path after printing (mainly  FIG. 5  and  FIG. 6 ). 
     A printer having the configuration disclosed in JP-A-10-217572 exhibits a sufficient heating effect even though the heater does not come into contact with the paper over the entire surface. Further, in the printer, the vapor generated from the rear surface of the paper can be removed to the outside at any time. Moreover, in the printer, a difference in dry speed between both sides of the paper is decreased, and thus a bending of the paper can be substantially reduced. As a result, a carrying error which is generated in a transferring operation of the paper is not caused in the printer. 
     However, in the configuration described in JP-A-10-217572, since the paper is heated from the rear surface of the paper through the guide member having the mesh structure, efficiency in transferring the heat to the rear surface of the paper is low. Especially, in one-path high speed printing apparatus in which an ink jet head having the same width as the paper is used, it is difficult to sufficiently remove the moisture which is contained in the paper. 
     Further, in JP-A-10-217572, the heater does not come into sufficient contact with the paper upon being heated for drying, and it is difficult to efficiently transfer the heat generated from the heater to the paper. 
     An object of the present invention is to provide an ink jet recording apparatus, which can efficiently dry a paper on which an image is formed with ink. 
     SUMMARY 
     According to one aspect of the present invention, there is provided an ink jet recording apparatus including: an ink jet head in which a plurality of nozzles are arranged; a sub-scan driving unit which carries a recording medium to be formed with an image; a first carrying unit which is disposed on a downstream side of a carrying direction of the recording medium by the sub-scan driving unit and carries the recording medium on which an image is formed by the ink jet head; and a second carrying unit which is disposed so as to face the first carrying unit and heats the recording medium interposed between the first carrying unit and the second carrying unit. 
     According to one aspect of the present invention, there is provided an ink jet recording apparatus including: an ink jet head in which a plurality of nozzles are arranged; a sub-scan driving unit which carries a recording medium to be formed with an image; a first roller which is disposed on a downstream side of a carrying direction of the recording medium by the sub-scan driving unit and carries the recording medium on which an image is formed by the ink jet head; and a second roller which is disposed so as to face the first roller and heats the recording medium. 
     According to one aspect of the present invention, there is provided a drying method using an ink jet recording apparatus which includes an ink jet head in which a plurality of nozzles are arranged, a sub-scan driving unit which carries a recording medium to be formed with an image, and a heat-fixing unit which is disposed on a downstream side of a carrying direction of the recording medium by the sub-scan driving unit and heats the recording medium on which an image is formed by the ink jet head, the method including: carrying the recording medium while interposing both surfaces of an image forming surface and an opposite surface to the image forming surface of the recording medium; and heating the recording medium from the opposite surface to the image forming surface. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view illustrating an ink jet recording apparatus viewed from a horizontal direction of a first embodiment. 
         FIG. 2  is a cross-sectional view illustrating a configuration of a heat-fixing device viewed from a horizontal direction of the first embodiment. 
         FIG. 3  is an external view of an upper carrying belt of the heat-fixing device of the first embodiment. 
         FIG. 4  is a cross-sectional view illustrating a guide viewed in a height direction of the heat-fixing device of the first embodiment. 
         FIG. 5  is a cross-sectional view illustrating a modified example of the heat-fixing device viewed from a horizontal direction of the first embodiment. 
         FIG. 6  is a cross-sectional view illustrating another modified example of the heat-fixing device viewed from a horizontal direction of the first embodiment. 
         FIG. 7  is a top perspective view schematically illustrating an appearance of an ink jet recording apparatus of a second embodiment. 
         FIG. 8  is a top perspective view illustrating a configuration of the heat-fixing device of the second embodiment. 
         FIG. 9  is a plan view illustrating a configuration of the heat-fixing device of the second embodiment. 
         FIG. 10  is a top perspective view illustrating a modified example of the heat-fixing device of the second embodiment. 
         FIG. 11  is a plan view illustrating a configuration of the heat-fixing device of the second embodiment shown in  FIG. 10 . 
         FIG. 12  is a top perspective view illustrating another modified example of the heat-fixing device of the second embodiment. 
         FIG. 13  is a plan view illustrating a configuration of the heat-fixing device of the second embodiment shown in  FIG. 12 . 
         FIG. 14  is a top perspective view illustrating another modified example of the heat-fixing device of the second embodiment. 
         FIG. 15  is a cross-sectional view illustrating another modified example of the heat-fixing device viewed from a horizontal direction of the second embodiment. 
         FIG. 16  is a block diagram illustrating a control system of the ink jet recording apparatus of the first embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments will be described. 
       FIG. 1  is a cross-sectional view illustrating an ink jet recording apparatus  1  viewed from a horizontal direction of a first embodiment.  FIG. 16  is a block diagram illustrating a control system of the ink jet recording apparatus  1  of the first embodiment. 
     A first paper cassette  100  and a second paper cassette  101  contain the recording mediums p which are different in size, respectively. A first paper feeding roller  102  withdraws the recording medium p corresponding to a selected size of the recording medium from the first paper cassette  100  to be carried to a pair of first carrying rollers  104  and a pair of resist rollers  106 . Similarly, a second paper feeding roller  103  withdraws the recording medium p corresponding to a selected size of the recording medium from the second paper cassette  101  to be carried to a pair of second carrying rollers  105  and the pair of resist rollers  106 . 
     A carrying belt  107  is applied with tension by a driving roller  108  and two driven rollers  109 . In a surface of the carrying belt  107 , holes are made at a predetermined interval. In addition, in the inside of the carrying belt  107 , a negative pressure chamber  111  is provided so as to be connected to a fan  110  in order to absorb the recording medium p to the carrying belt  107 . The driving roller  108  drives the carrying belt  107  so as to carry the recording medium p from an upstream side on which the pair of the resist rollers  106  are formed as a paper feeding unit to a downstream side on which a pair of first carrying rollers  112 , a pair of second carrying rollers  113 , and a pair of third carrying rollers  114  are formed as the paper feeding unit. A carrying direction of the recording medium p is a sub-scan direction when it is viewed from a recording operation in the ink jet recording apparatus  1 . 
     In the downstream side of the carrying direction of the recording medium p on the carrying belt  107 , a heat-fixing device  120  which heats the image-formed recording medium p, the pair of the first carrying rollers  112 , the pair of the second carrying rollers  113 , and the pair of the third carrying rollers  114  are disposed. The heat-fixing device  120  will be described in detail later. 
     Above the carrying belt  107 , ink jet heads which eject inks to the recording medium according to image data are disposed on four lines. Specifically, from the upstream side, an ink jet head  115 C which ejects a cyan (C) ink, an ink jet head  115 M which ejects a magenta (M) ink, an ink jet head  115 Y which ejects a yellow (Y) ink, and an ink jet head  115 Bk which ejects a black (Bk) ink are disposed in this order. 
     In the ink jet heads  115 C,  115 M,  115 Y, and  115 Bk, nozzles are disposed at a predetermined resolution along a width direction of the recording medium p, respectively. That is, the ink jet heads  115 C,  115 M,  115 Y, and  115 Bk are line type print heads in which plural nozzles are arranged on a line. In the ink jet heads  115 C,  115 M,  115 Y, and  115 Bk, the nozzles are arranged in a direction perpendicular to the carrying direction of the recording medium p by the carrying belt  107 . The nozzles are arranged so as to be positioned with a defined distance with respect to the recording medium p which is located on the carrying belt  107 . Here, an alignment direction of the nozzles is a main scan direction. 
     The ink jet recording apparatus  1  of the first embodiment is provided with the line type ink jet heads  115 C,  115 M,  115 Y, and  115 Bk on the carrying belt  107  which carries the recording medium p. The ink jet heads  115 C,  115 M,  115 Y, and  115 Bk perform the recording operation on the recording medium p on the basis of image signals inputted. If the ink jet heads  115 C,  115 M,  115 Y, and  115 Bk is a line type, any driving scheme thereof is sufficient. That is, in the ink jet heads  115 C,  115 M,  115 Y, and  115 Bk, a scheme using thermoelectric conversion elements, a scheme using electrostrictive conversion elements, or other schemes of ink ejecting scheme are applicable. 
     The carrying belt  107  and the driving roller  108  are sub-scan driving units which relatively move the recording medium p and the ink jet heads  115 C,  115 M,  115 Y, and  115 Bk in the sub-scan direction perpendicular to the alignment direction of the nozzles. That is, the carrying belt  107  and the driving roller  108  perform a sub-scan driving process in which the recording medium p and the ink jet heads  115 C,  115 M,  115 Y, and  115 Bk are relatively moved in the sub-scan direction perpendicular to the alignment direction of the nozzles. 
     That is, the ink jet recording apparatus  1  of the first embodiment performs the recording operation on the recording medium p in the line scheme (one path recording scheme). A control unit  300  controls the ink jet heads  115 C,  115 M,  115 Y, and  115 Bk to be driven on the basis of the image signals to perform a main scan driving process in which ink droplets are selectively ejected from the nozzles. In addition, the control unit  300  controls the driving roller  108  to be driven by a driving motor  301 . The control unit  300  performs the sub-scan driving process in which the ink jet heads  115 C,  115 M,  115 Y, and  115 Bk and the recording medium p are relatively moved in the sub-scan direction. The recording operation is performed by the main scan driving process and the sub-scan driving process. 
     Further, in the ink jet heads  115 C,  115 M,  115 Y, and  115 Bk, a cyan (C) ink cartridge  116 C, a magenta (M) ink cartridge  116 M, a yellow (Y) ink cartridge  116 Y, and a black (Bk) ink cartridge  116 Bk in which respective colors are filled are provided. The ink jet head  115 C and the ink cartridge  116 C, the ink jet head  115 M and the ink cartridge  116 M, the ink jet head  115 Y and the ink cartridge  116 Y, and the ink jet head  115 Bk and the ink cartridge  116 Bk are connected through tubes  117 , respectively. 
     Here, an example of composition in aqueous inks of black, yellow, cyan, and magenta will be shown. 
     
       
         
           
               
             
               
                   
               
             
            
               
                 Black1 
               
               
                 Self-dispersed carbon black dispersion liquid 
               
               
                 (Made by Cabot Specialty Chemicals Ink) 
               
            
           
           
               
               
               
            
               
                 (Carbon black solid content concentration) 
                 8.0% 
                 by weight 
               
               
                 Glycerin 
                 30.0% 
                 by weight 
               
               
                 Ethylene glycol mono butyl ether 
                 0.5% 
                 by weight 
               
               
                 Surfynol 465 
                 1.0% 
                 by weight 
               
               
                 Proxel XL-2 (S) 
                 0.2% 
                 by weight 
               
               
                 Ion-exchange water remaining amount 
                 (60.3% 
                 by weight) 
               
            
           
           
               
            
               
                 Black2 
               
               
                 Self-dispersed carbon black dispersion liquid 
               
               
                 (Made by Cabot Specialty Chemicals Ink) 
               
            
           
           
               
               
               
            
               
                 (Carbon black solid content concentration) 
                 8.0% 
                 by weight 
               
               
                 Glycerin 
                 30.0% 
                 by weight 
               
               
                 Ethylene glycol 
                 10.0% 
                 by weight 
               
               
                 Diethylene glycol mono butyl ether 
                 5.0% 
                 by weight 
               
               
                 Surfynol 465 
                 1.0% 
                 by weight 
               
               
                 Proxel XL-2 (S) 
                 0.2% 
                 by weight 
               
               
                 Ion-exchange water remaining amount 
                 (45.8% 
                 by weight) 
               
            
           
           
               
            
               
                 Yellow 
               
               
                 Self-dispersion yellow dispersion liquid 
               
               
                 (Made by Cabot Specialty Chemicals Ink) 
               
            
           
           
               
               
               
            
               
                 (Yellow pigment solid content concentration) 
                 6.0% 
                 by weight 
               
               
                 Glycerin 
                 45.0% 
                 by weight 
               
               
                 Ethylene glycol mono butyl ether 
                 5.0% 
                 by weight 
               
               
                 Surfynol 465 
                 1.0% 
                 by weight 
               
               
                 Proxel XL-2 (S) 
                 0.2% 
                 by weight 
               
               
                 Ion-exchange water remaining amount 
                 (42.8% 
                 by weight) 
               
            
           
           
               
            
               
                 Magenta 
               
               
                 Polymer dispersant dispersed magenta dispersion liquid 
               
               
                 (Made by Fuji coloring matter) 
               
            
           
           
               
               
               
            
               
                 (Magenta pigment solid content concentration) 
                 6.0% 
                 by weight 
               
               
                 Glycerin 
                 45.0% 
                 by weight 
               
               
                 Diethylene glycol mono butyl ether 
                 5.0% 
                 by weight 
               
               
                 Surfynol 465 
                 1.0% 
                 by weight 
               
               
                 Proxel XL-2 (S) 
                 0.2% 
                 by weight 
               
               
                 Ion-exchange water remaining amount 
                 (42.8% 
                 by weight) 
               
            
           
           
               
            
               
                 Cyan 
               
               
                 Polymer dispersant dispersed cyan dispersion liquid 
               
               
                 (Made by Fuji coloring matter) 
               
            
           
           
               
               
               
            
               
                 (Cyan pigment solid content concentration) 
                 6.0% 
                 by weight 
               
               
                 Glycerin 
                 45.0% 
                 by weight 
               
               
                 Triethylene glycol mono butyl ether 
                 5.0% 
                 by weight 
               
               
                 Surfynol 465 
                 1.0% 
                 by weight 
               
               
                 Proxel XL-2 (S) 
                 0.2% 
                 by weight 
               
               
                 Ion-exchange water remaining amount 
                 (57.2% 
                 by weight) 
               
               
                   
               
            
           
         
       
     
     The above-mentioned ink includes water of 60.3% by weight as a maximum value and at least 42.8% by weight as a minimum value. Until the image is completely formed, it is necessary to dry the recording medium by evaporating the moisture down to an amount of moisture which is generally absorbed into the recording medium. 
     Next, an image formation by the ink jet recording apparatus  1  of the first embodiment will be described. 
     Firstly, when the control unit  300  obtains image data to be printed on the recording medium p via an external interface  302 , an image process begins. The control unit  300  transfers the image data subjected to the image process to the ink jet heads  115 C,  115 M,  115 Y, and  115 Bk. Here, the ink jet heads  115 C,  115 M,  115 Y, and  115 Bk are connected with respective colors of the ink cartridges  116 C,  116 M,  116 Y, and  116 Bk through the tubes  117 , respectively. In the ink jet heads  115 C,  115 M,  115 Y, and  115 Bk, proper inks are supplied on the basis of the image data. 
     The first paper feeding roller  102  or the second paper feeding roller  103  withdraws the recording medium p corresponding to the selected size of the recording medium one by one from the first paper cassette  100  or the second paper cassette  101 . The recording medium p is carried to the pair of the first carrying rollers  104  or the pair of the second carrying rollers  105  and the pair of the resist rollers  106 . 
     The pair of the resist rollers  106  corrects a skew of the recording medium p and begins to carry the recording medium at a predetermined timing. By reducing pressure in the negative pressure chamber  111 , air is drawn through holes of the carrying belt  107 . The recording medium p which is absorbed on the carrying belt  107  is carried to a position facing the ink jet heads  115 C,  115 M,  115 Y, and  115 Bk. Therefore, a distance between the ink jet heads  115 C,  115 M,  115 Y, and  115 Bk and the recording medium p is maintained at a constant interval, for example, 0.5 to 2.0 mm. The control unit  300  is synchronized with the timing when the recording medium p is carried from the pair of the resist rollers  106 , and ejects the respective colors from the ink jet heads  115 C,  115 M,  115 Y, and  115 Bk. Since the nozzles of the ink jet heads  115 C,  115 M,  115 Y, and  115 Bk are arranged along the width direction of the recording medium p, when the recording medium p is carried, a full color image is formed on the entire surface of the recording medium p. 
     After the Bk ink ejected from the ink jet head  115 Bk is finally landed on the recording medium p and a predetermined time lapses, the carrying belt  107  carries the recording medium p to the heat-fixing device  120 . The heat-fixing device  120  is a mechanism for evaporating the moisture which is included in the recording medium p in the middle of being passed. The recording medium p dried by the head-fixing device  120  is discharged to a discharge tray  118  by the pair of the first carrying rollers  112 , the pair of the second carrying rollers  113 , and the pair of the third carrying rollers  114 . 
     Next, the heat-fixing device  120  which is provided on a downstream side of the ink jet recording apparatus  1  of the first embodiment will be described. 
     As shown in  FIG. 2 , in the heat-fixing device  120 , a lower carrying belt  123  which is hung on rollers  121  and  122  and an upper carrying belt  126  which is hung on rollers  124  and  125  are disposed so as to be faced and to come into contact with each other. Here, the control unit  300  drives the roller  124  by using a driving motor  304 . The upper carrying belt  126  is driven by a rotation of the roller  124 . In addition, as the roller  124  hung on the upper carrying belt  126  is rotatably driven, the roller  121  is rotated and thus the lower carrying belt  123  is driven. Therefore, the lower carrying belt  123  and the upper carrying belt  126  carry the recording medium p at the same speed in the same direction. Here, the relation between driving and driven is only an example, even though the relation between driving and driven is changed or the rollers are separately operated, it may be applicable as long as the roller  121  and the roller  124  are rotated in synchronization with each other. 
     The lower carrying belt  123  and the upper carrying belt  126  include a metal conductive layer and a solid rubber layer from the inside thereof in this order. As a material of the metal conductive layer, for example, nickel (having a thickness of 40 to 100 μm) is used. In the metal conductive layer, stainless steel, aluminum, and a composite material of stainless steel and aluminum may be used. The solid rubber layer includes a silicon rubber having a thickness of 200 μm. As shown in  FIG. 3 , in the upper carrying belt  126 , plural holes  400  having a diameter of Φ 2 mm are made at a predetermined interval. The holes  400  are provided, for example, at 6 mm interval so as to be inclined with 45 degree with respect to the sub-scan direction. A surface of the image-formed recording medium p comes into contact with the upper carrying belt  126  on which the holes  400  are provided. 
     A guide  128  is provided in the inside of the upper carrying belt  126 , through which vapor generated by heating the image-formed recording medium p is diffused to the outside of the heat-fixing device  120 . In the inside of the roller  121  which is hung on the upstream side of the lower carrying belt  126 , a halogen lamp  127  is disposed. A surface temperature of the lower carrying belt  123  is maintained in a range of 50 to 250° C., preferably 100 to 200° C. via the roller  121 . In this state, when the lower carrying belt  123  and the upper carrying belt  126  are rotated, heat is transferred from the lower carrying belt  123  to the upper carrying belt  126 , and the upper carrying belt  126  is also heated. 
     An IH heater may be used in the internal of the roller  121  instead of the halogen lamp  127 . Further, it may be possible that the roller  121  is made of a metal material, for example, iron or the like, and an IH coil may be provided therein. In this case, the heat occurs from the roller  121  by an eddy-current which is generated by the IH coil. Since the heat occurs in the roller  121  itself, the roller  121  has excellent thermal conductivity with respect to the recording medium p. In addition, the IH coil can rise rapidly in temperature. 
     When the lower carrying roller  123  is heated up to a predetermined temperature, the control unit  300  allows the ink jet heads  115 C,  115 M,  115 Y, and  115 Bk to perform the recording operation. When the lower carrying belt  123  and the upper carrying belt  126  carry the recording medium p, on which the image is formed, interposed therebetween, the heat is transferred on the recording medium p from the both of the lower carrying belt  123  and the upper carrying belt  126 . The vapor is generated from the recording medium p. The generated vapor flows into the inside of the upper carrying belt  126  through the plural holes of the upper carrying belt  126 . 
     The vapor flowing into the inside of the upper carrying belt  126  is diffused to the outside of the heat-fixing device  120  along the guide  128 . The recording medium p which is passed through the heat-fixing device  120  is kept in tight contact with between the lower carrying belt  123  and the upper carrying belt  126 . So, the recording medium p is good in the thermal conductivity and its temperature rises rapidly. In addition, since the recording medium p is heated by being interposed between the lower carrying belt  123  and the upper carrying belt  126 , the recording medium p is carried from the heat-fixing device  120  to the pair of the first carrying rollers  112  or later without cockle or deformation. 
       FIG. 4  is a cross-sectional view taken on a line X-X′ in a height direction of the guide  128  which is provided in the inside of the upper carrying belt  126 . The guide  128  is made of a stainless or a heat resistant resin. A lower side of the guide  128  where the recording medium p is faced is opened. Therefore, the vapor generated from the recording medium p flows from the opening to the inside of the guide  128 . 
     A fan  140  which is provided on the upstream side (left side in the drawing) blows air along a direction of arrow in the drawing. The fan  140  diffuses the generated vapor from the downstream side. The control unit  300  drives the fan  140  via a driving motor  303  such that it blows air before the recording medium p passes through the heat-fixing device  120 , and then the fan  140  also blows air for a predetermined time after the recording medium p passed there. It is because the vapor in the guide  128  is completely diffused. 
       FIG. 5  is a modified example of the heat-fixing device  120  of the first embodiment. Alignments of the rollers  121  and  122  and the lower carrying belt  123 , the rollers  124  and  125  and the upper carrying belt  126 , and the guide  128  are similar to that of the configuration shown in  FIG. 2 . Here, instead of the halogen lamp  127  shown in  FIG. 2 , a heater  129  such as a ceramic heater is provided on an opposite side to a surface where the lower carrying belt  123  comes into contact with the recording medium p. 
     The heat generated from the heater  129  is propagated to the recording medium p via the lower carrying belt  123 . The moisture contained in the recording medium p is heated to be vapor. As described in  FIG. 2 , the generated vapor is diffused to the outside of the heat-fixing device  120  through the plural holes  400  and the guide  128  which are provided at the upper carrying belt  126 . The same effects are obtained from the heat-fixing device  120  shown in  FIG. 5  as that of the heat-fixing device  120  shown in  FIG. 2 . 
       FIG. 6  is another modified example of the heat-fixing device  120  of the first embodiment. An upper carrying belt  134  which is hung on rollers  132  and  133  is disposed so as to come into contact with a heat roller  130 . The recording medium p is carried by being interposed between the upper carrying belt  134  and the heat roller  130 . In the inside of the heat roller  130 , a halogen lamp  131  is provided. A surface temperature of the heat roller  130  is maintained in a range of 50 to 250° C., preferably 100 to 200° C. 
     Here, the control unit  300  drives the roller  132  by using a driving motor  305 . The upper carrying belt  134  is driven by the rotation of the roller  132 . In addition, as the roller  132  hung on the upper carrying belt  134  is rotatably driven, the heat roller  130  is rotatably driven. Therefore, the upper carrying belt  134  and the heat roller  130  carry the recording medium p at the same speed in the same direction. Here, the relation between driving and driven is only an example, even though the relation between driving and driven is changed or the rollers are separately operated, it may be applicable as long as the upper carrying belt  134  and the heat roller  130  are rotated in synchronization with each other. 
     The heat roller  130  comes into direct contact with the recording medium p. The heat roller  130  propagates the heat to the recording medium p on which the image is formed. The moisture contained in the recording medium p is heated to be vapor. As described in  FIG. 2 , the generated vapor is diffused to the outside of the heat-fixing device  120  through the holes of the upper carrying belt  134  and the guide  128 . The same effects are obtained from the heat-fixing device  120  shown in  FIG. 6  as that of the heat-fixing device  120  shown in  FIG. 2 . 
     According to the first embodiment described above, the recording medium p on which the image is formed by aqueous ink and contains the moisture is heated by being interposed between the lower carrying belt  123  and the upper carrying belt  126 , or between the upper carrying belt  134  and the heat roller  130 . For this reason, the recording medium p is efficiently heated. 
     Since the halogen lamp  127  is provided at the lower carrying belt  123 , the recording medium p is mainly heated from the rear surface on which the image is not formed. The moisture contained in the image-formed recording medium p is unevenly distributed on the surface on which the image is formed. For this reason, the vapor which is generated from the recording medium p does not pass through the inside of the recording medium p, but being diffused to the outside of the recording medium p. Therefore, the recording medium p is not swollen by the vapor. 
     In addition, in the upper carrying belt  126  or the upper carrying belt  134  as a path for diffusing the vapor, which is generated from the recording medium p, plural holes  400  are provided. The vapor which is generated from the recording medium p is rapidly evaporated from the recording medium p. For this reason, the recording medium p is sufficiently dried by the configuration of the first embodiment. The vapor flows into the heat-fixing device  120  through the plural holes  400  which are provided in the upper carrying belt  126 , is diffused to the outside of the heat-fixing device  120  along the guide  128  which is provided on the inside of the upper carrying belt  126  or the upper carrying belt  134 . The vapor does not remain in the heat-fixing device  120 . Therefore, the vapor is not condensed on a portion in which the temperature is low in the heat-fixing device  120 , or parts made of metal does not become rusty. 
     As described above, according to the first embodiment, even though the plain paper is printed by using the aqueous ink, the cockling is not generated, so that a high quality of image can be formed on the recording medium p. 
     Next, a second embodiment will be described.  FIG. 7  is a top perspective view schematically illustrating an appearance of the ink jet recording apparatus  1  of the second embodiment. 
     The ink jet recording apparatus  1  of the second embodiment is different in configuration of the heat-fixing device  120  of the ink jet recording apparatus  1  of the first embodiment shown in  FIG. 1 . As shown in  FIG. 7 , in the ink jet recording apparatus  1  of the second embodiment, the heat-fixing device  120  is provided with a heat roller  150  and a pressure roller  151 . 
     The configuration up to a portion where the recording medium p is carried to the heat-fixing device  120  is similar to that of the first embodiment described above. After the recording operation of the ink jet heads  115 C,  115 M,  115 Y, and  115 Bk on the recording medium p, the carrying belt  107  carries the recording medium p to the heat-fixing device  120 . 
     The pressure roller  151  is disposed above the heat roller  150  on the same axis along the height direction of the ink jet recording apparatus  1 . The heat roller  150  is a thermal source which includes the halogen lamp or the IH heater therein. Further, it may be possible that the heat roller  150  is made of a metal material and an IH coil is provided in the internal thereof. 
     The pressure roller  151  is disposed so as to come into pressing contact with the heat roller  150 . The pressure roller  151  presses and carries the recording medium p to the heat roller  150 . Here, the control unit  300  drives the heat roller  150  by using a driving motor  306 . As the heat roller  150  is rotated, the pressure roller  151  is rotatably driven. Therefore, the heat roller  150  and the pressure roller  151  carry the recording medium p at the same speed in the same direction. Here, the relation between driving and driven is only an example, even though the relation between driving and driven is changed or the rollers are separately operated, it may be applicable as long as the heat roller  150  and the pressure roller  151  are rotated in synchronization with each other. Using the heat roller  150  formed as a heating unit and the pressure roller  151  formed as a pressing unit, the heat-fixing device  120  is a heat-fixing unit which heats the image-formed recording medium p. 
     In addition, as shown in  FIG. 7 , a pair of a heat roller  152  and a pressure roller  153  may be provided on the upstream side of the ink jet heads  115 C,  115 M,  115 Y, and  115 Bk along the carrying direction of the recording medium p. The heat roller  152  and the pressure roller  153  preheat the recording medium p before the ink jet heads  115 C,  115 M,  115 Y, and  115 Bk begin to perform the recording operation on the recording medium p. Since the ink jet heads  115 C,  115 M,  115 Y, and  115 Bk perform the recording operation on the preheated recording medium p, the moisture is evaporated from the recording medium p even though before the recording medium p is carried to the heat roller  150  and the pressure roller  151 . Also in the first embodiment shown in  FIG. 1 , the pair of the heat roller  152  and the pressure roller  153  can be provided. 
       FIG. 8  is a top perspective view illustrating a configuration of the heat-fixing device  120  of the second embodiment. In addition,  FIG. 9  is a plan view illustrating a surface taken on lines A-A′ and B-B′ of the pressure roller  151  shown in  FIG. 8  when it is viewed from the heat roller  150 . 
     On the surface of the pressure roller  151 , plural first wire members  160  which are disposed so as to be extended in a direction along the sub-scan direction, and plural second wire members  161  which are disposed so as to be extended in the main scan direction cross to the first wire members  160  are provided. On the surface of the pressure roller  151 , a number of mesh convex portions are formed by the plural first wire members  160  and the plural second wire members  161 . The plural first wire members  160  and the plural second wire members  161  may be formed so as to be perpendicular to each other or to be provided so as to be crossed with different inclinations. 
     The convex portions provided on the surface of the pressure roller  151  press the recording medium p to the heat roller  150  so as to come into contact therewith. Therefore, the convex portions provided on the surface of the pressure roller  151  efficiently propagate the heat to the recording medium p by heating of the heat roller  150 . In addition, a width W of the main scan direction which is a range of the convex portions provided on the surface of the pressure roller  151  is wider than that of the recording medium p. For this reason, the pressure roller  151  presses the recording medium p over the entire surface thereof. 
     In portions except for the convex portions which are formed by the plural first wire members  160  and the plural second wire members  161  which are provided on the surface of the pressure roller  151 , concave portions are formed. When the pressure roller  151  presses the recording medium p, the concave portions provided on the surface of the pressure roller  151  serve as gaps between the recording medium p and the pressure roller  151  to diffuse the moisture in ink which is contained in the recording medium p heated by the heat roller  150  to the atmosphere. Therefore, the moisture in ink which is contained in the recording medium p heated by the heat roller  150  does not remain in the recording medium p, but is efficiently diffused as the vapor to the atmosphere through the concave portions of the surface of the pressure roller  151 . 
     Here, if area of the convex portions provided on the surface of the pressure roller  151  becomes larger, an effect that the ink contained in the recording medium p is accelerated to be heat-fixed is increased according to the area pressing the recording medium p to the heat roller  150 . On the other hand, if the area of the concave portions provided on the surface of the pressure roller  151  becomes smaller, the effect that the moisture in ink which is contained in the recording medium p is diffused to the atmosphere to be vapor is decreased. 
     If the area of the convex portions provided on the surface of the pressure roller  151  becomes smaller, the area of the concave portions provided on the surface of the pressure roller  151  becomes larger, so that the effect that the moisture in ink which is contained in the recording medium p is diffused to the atmosphere to be vapor is increased. On the other hand, if the area of the convex portions provided on the surface of the pressure roller  151  becomes smaller, the effect that the ink contained in the recording medium p is accelerated to be heat-fixed is decreased. As a result, the ink contained in the recording medium p remains to be unfixed. 
     In the heat-fixing device  120  of the second embodiment, the mesh convex portions are disposed at a moderate interval on the surface of the pressure roller  151 . Therefore, while accelerating the heat-fixing of the ink with respect to the recording medium p, the moisture in ink which is contained in the recording medium p can be diffused to the atmosphere to be vapor. Further, it is possible to substantially prevent the bending of the recording medium p. 
       FIG. 10  is a modified example of the heat-fixing device  120  of the second embodiment.  FIG. 10  is a top perspective view illustrating a configuration example of the heat-fixing device  120 . In addition,  FIG. 11  is a plan view illustrating a surface taken on lines C-C′ and D-D′ of the pressure roller  151  shown in  FIG. 10  when it is viewed from the heat roller  150 . 
     On the surface of the pressure roller  151 , at least one or more grooves  162  are provided so as to be extended in a direction along the sub-scan direction. On the surface of the pressure roller  151  with the grooves  162 , a number of concave portions and convex portions are formed. 
     The convex portions provided on the surface of the pressure roller  151  press the recording medium p to the heat roller  150  so as to come into contact therewith. Therefore, the convex portions provided on the surface of the pressure roller  151  efficiently propagate the heat to the recording medium p by heating of the heat roller  150 . In addition, the width W of the main scan direction which is the range of the convex portions provided on the surface of the pressure roller  151  is wider than that of the recording medium p. For this reason, the pressure roller  151  presses the recording medium p over the entire surface thereof. 
     When the pressure roller  151  presses the recording medium p, the grooves  162  provided on the surface of the pressure roller  151  serve as gaps between the recording medium p and the pressure roller  151  to diffuse the moisture in ink which is contained in the recording medium p heated by the heat roller  150  to the atmosphere. Therefore, the moisture in ink which is contained in the recording medium p heated by the heat roller  150  does not remain in the recording medium p, but is efficiently diffused as the vapor to the atmosphere through the grooves  162  of the surface of the pressure roller  151 . 
       FIG. 12  is another modified example of the heat-fixing device  120  of the second embodiment.  FIG. 12  is a top perspective view illustrating a configuration example of the heat-fixing device  120 . In addition,  FIG. 13  is a plan view illustrating a surface taken on lines E-E′ and F-F′ of the pressure roller  151  shown in  FIG. 12  when it is viewed from the heat roller  150 . On the surface of the pressure roller  151 , spiral grooves  162  are provided along the main scan direction. 
     As described above, the convex portions provided on the surface of the pressure roller  151  press the recording medium p to the heat roller  150  so as to come into contact therewith, so that the moisture in ink which is contained in the recording medium p is efficiently diffused to the atmosphere to be vapor through the grooves  162  provided on the surface of the pressure roller  151 . 
       FIG. 14  is another modified example of the heat-fixing device  120  of the second embodiment.  FIG. 14  is a top perspective view illustrating a configuration example of the heat-fixing device  120 . On the surface of the pressure roller  151 , a sponge-shaped porous material  163  is formed. The porous material  163  is provided with a number of minute spaces on its surface. In addition, a width W of the main scan direction which is a range of the porous material  163  provided on the surface of the pressure roller  151  is wider than that of the recording medium p. For this reason, the pressure roller  151  presses the recording medium p over the entire surface thereof. 
     When the pressure roller  151  presses the recording medium p, the minute spaces of the porous material  163  provided on the surface of the pressure roller  151  serve as gaps between the recording medium p and the pressure roller  151  to diffuse the moisture in ink which is contained in the recording medium p heated by the heat roller  150  to the atmosphere. Therefore, the moisture in ink which is contained in the recording medium p heated by the heat roller  150  does not remain in the recording medium p, but is efficiently diffused as the vapor to the atmosphere. 
     In the second embodiment described above, there are provided with a number of the concave portions and the convex portions on the surface of the pressure roller  151 . On the other hand, as shown in  FIG. 15 , it also may be possible that the moisture in ink which is contained in the recording medium p may be diffused to the atmosphere through the convex portions of the pressure roller  151  which faces and presses the recording medium p.  FIG. 15  is a cross-sectional view illustrating the heat-fixing device  120  viewed from a horizontal direction. Through holes  164  are provided from a space in the pressure roller  151  to a surface of the convex portions of the pressure roller  151 . The moisture in ink which is contained in the recording medium p heated by the heat roller  150  is diffused through not only the concave portions of the pressure roller  151  but also the through holes  164  which is provided in the convex portions of the pressure roller  151  which is a contact surface with the recording medium p. In the inside of the pressure roller  151 , it may be effective that an absorbing device is used for efficiently absorbing the vapor through the through holes  164 .