Patent Publication Number: US-7896487-B2

Title: Printer and transferring body

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application claims priority from Japanese Patent Application No. 2006-010598, filed on Jan. 19, 2006, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a printer which performs printing by transporting a liquid to a recording medium such as a recording paper, and a transferring body which transfers a liquid droplet of the liquid to the recording medium. 
     2. Description of the Related Art 
     Among printers which perform printing on a recording medium such as a recording paper by discharging an ink droplet from a nozzle, there is a printer in which the ink droplet from the nozzle is adhered to a transferring body once, and then the ink droplet adhered to the transferring body is transferred to a recording medium. For example, in an image recording apparatus (printer) described in Japanese Patent Application Laid-open No. 2004-291275, a plurality of lyophilic ink-philic parts (lyophilic areas), having a wettability (having low liquid repellent property) for ink, on a surface of a transferring drum (transferring body) to which the ink is adhered, are arranged in the form of a lattice, and an ink-phobic part (liquid repellent area) which does not have wettability for the ink (having high liquid repellent property) is formed in an area other than the area in which the ink-philic parts are formed. Accordingly, even when a position of landing (landing position) of the ink which is discharged from the nozzle is deviated from a desired position on the surface of the transferring drum, the ink is landed at an appropriate position on the surface of the transferring drum since the ink adhered to the ink-phobic part moves to the ink-philic part. 
     However, in the image recording apparatus described in Japanese Patent Application Laid-open No. 2004-291275, when an ink droplet larger than the ink-phobic part is adhered, there is a possibility that there is a position shift of an adhering position of a portion of the ink droplet which protrudes from (sticks out of) the ink-philic part. On the other hand, when an ink droplet smaller than the ink-philic part is adhered, there is a possibility that there is a position shift of an adhering position of the ink droplet within the ink-philic part. Due to such a position shift of the adhering position of the ink droplet, there is a possibility that in a case of performing a liquid droplet gradation in which the printing is performed by discharging ink droplets of a plurality of types of inks having mutually different volumes, the printing quality is declined. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a printer and a transferring body in which a position shift of a final adhering position of a liquid droplet on the transferring body hardly occurs. A reference numeral in bracket assigned to each component shown below is only for exemplifying that component, and does not restrict the component. 
     According to a first aspect of the present invention there is provided a printer ( 1 ) which performs printing on a recording medium (P) by discharging liquid droplets, including a liquid droplet discharging section ( 2 ) which has a plurality of discharge ports ( 15 ), and a transferring body ( 3 ) which transfers, to the recording medium (P), liquid droplets discharged from the discharging ports ( 15 ), and which has on a surface ( 3   a ) thereof a plurality of lyophilic areas ( 50 ), a plurality of circumferential areas ( 53 ) surrounding the lyophilic areas ( 50 ), and a liquid repellent area ( 51 ) surrounding the circumferential areas ( 53 ). A liquid repellent property on the circumferential areas ( 53 ) is progressively increased at positions away from a center of the lyophilic area ( 50 ). 
     In this case, when an adhering position on the transferring body ( 3 ), of the liquid droplet discharged from the liquid droplet discharging section ( 2 ) is shifted, and when the liquid droplet is adhered to one of the circumferential areas ( 53 ), the liquid droplet moves to the lyophilic area ( 50 ) having low liquid repellent property. At this time, since a liquid repellent property of the circumferential areas ( 53 ) is increased progressively at positions away from a center of the lyophilic area ( 50 ), even when the liquid droplet is larger than the lyophilic area ( 50 ), the liquid droplet moves toward the center of the lyophilic area ( 50 ). Accordingly, the position shift in the final adhering position of the liquid droplet with respect to the transferring body ( 3 ) hardly occurs, and a printing quality is improved. 
     In the printer ( 1 ) of the present invention, on each of the circumferential areas ( 53 ), a proportion of an area of the liquid repellent area ( 51 ) with respect to an area of the lyophilic area ( 50 ), may increase progressively at positions away from the center of the lyophilic area ( 50 ). In this case, on each of the circumferential areas ( 53 ), it is possible to increase the liquid repellent property progressively, at positions away from the center of the lyophilic area ( 50 ). 
     In the printer ( 1 ) of the present invention, a boundary ( 52 ) between each of the lyophilic areas ( 50 ) and the liquid repellent area ( 51 ) may be serrated. In this case, on each of the circumferential areas ( 53 ), it is possible to increase progressively the proportion of the area of the liquid repellent area ( 51 ) at positions away from the center of the lyophilic area ( 50 ). 
     In the printer ( 1 ) of the present invention, in each of the circumferential areas ( 53 ), the lyophilic area ( 50 ) may form a pattern in which a plurality of projections ( 50   a ) projected acutely toward the liquid repellent area ( 51 ) are arranged. Even in this case, it is possible to increase progressively the proportion of the area of the liquid repellent area ( 51 ), at positions away from the center of the lyophilic area ( 50 ). 
     In the printer ( 1 ) of the present invention, in each of the circumferential areas ( 63 ), a plurality of island portions ( 62 ) having a liquid repellent property same as a liquid repellent property of a lyophilic area ( 60 ) may be arranged in a discrete manner in a liquid repellent area ( 61 ), and a distribution density of the island portions ( 62 ) may decrease progressively at positions away from a center of the lyophilic area ( 60 ). In this case, in each of the circumferential areas ( 63 ), it is possible to increase progressively the proportion of an area of the liquid repellent area ( 61 ) at positions away from the center of the lyophilic area ( 60 ). 
     In the printer ( 1 ) of the present invention, in each of circumferential areas ( 73 ), an intermediate area ( 72 ) having a liquid repellent property which is higher than a liquid repellent property of one of lyophilic areas ( 70 ), and is lower than a liquid repellent property of a liquid repellent area ( 71 ) may be provided along an entire circumference of one of the lyophilic areas ( 70 ). In this case, it is possible to improve gradually a liquid repellent property on each of the circumferential areas ( 73 ) progressively at positions away from the center of the lyophilic area ( 70 ). At this time, in each of the circumferential areas ( 73 ), the intermediate area ( 72 ) may be formed as a plurality of intermediate areas ( 72   a ,  72   b ) in a radial direction of one of the lyophilic areas ( 70 ), and a liquid repellent property of the intermediate areas ( 72   a ,  72   b ) may be increase progressively at positions away from the center of one of the lyophilic areas ( 70 ). In this case, it is possible to make a change in the liquid repellent property of each of the circumferential areas ( 73 ) gradually, and the liquid droplet adhered to one of the circumferential areas ( 73 ) tends to move easily toward the center of the lyophilic area ( 70 ). 
     In the printer ( 1 ) of the present invention, the liquid droplet discharging section ( 2 ) may discharge liquid droplets of different volumes. In this case, since in each of the circumferential areas ( 53 ), the liquid repellent property is increased progressively at positions away from the center of the lyophilic area ( 50 ), even when the liquid droplets of mutually different volumes are discharged, the liquid droplets move toward the center of the lyophilic area ( 50 ). Consequently, even when the liquid droplet gradation is performed, the position shift of the final landing position of the liquid droplet on the transferring body ( 3 ) hardly occurs, and the printing quality is improved. 
     In the printer ( 1 ) of the present invention, in the liquid droplet discharging section ( 2 ), the discharge ports ( 15 ) may be arranged in a predetermined direction, and in the transferring body ( 3 ), the lyophilic areas ( 50 ) may be arranged in the predetermined direction, and a spacing distance (P 1 ) between the discharge ports ( 15 ) in the predetermined direction may be same as a spacing distance (P 1 ) between the lyophilic areas ( 50 ) in the predetermined direction. In this case, since the liquid droplet is discharged from each of the discharge ports ( 15 ) to one of the corresponding lyophilic areas ( 50 ), the printing is performed assuredly. 
     In the printer ( 1 ) of the present invention, the transferring body ( 3 ) may have a substantially circular cylindrical shape, and may be rotatably attached to the printer ( 1 ) about a predetermined axis as a center, and the lyophilic areas ( 50 ) and the liquid repellent area ( 51 ) may be formed on a side surface ( 3   a ) of the transferring body ( 3 ), and the transferring body ( 3 ) may rotate about the predetermined axis as the center to discharge the ink droplets from the discharge ports ( 15 ) when each of the lyophilic areas ( 50 ) reaches a position facing one of the discharge ports ( 15 ). In this case, since the liquid droplet is discharged in a state in which one of the discharge ports ( 15 ) is adjacent to the one of the lyophilic areas ( 50 ), the liquid droplet is adhered assuredly to one of the lyophilic areas ( 50 ). 
     According to a second aspect of the present invention, there is provided a transferring body ( 3 ) which transfers, to a recording medium (P), a liquid droplet discharged from a liquid droplet discharging section ( 2 ), including a first area (C 3 ) which is formed on a surface ( 3   a ) of the transferring body ( 3 ), a transition area ( 53 ) which is formed on the surface ( 3   a ) of the transferring body ( 3 ), and which surrounds the first area (C 3 ), and a second area (C 4 ) which is formed on the surface ( 3   a ) of the transferring body ( 3 ), and which surrounds the transition area ( 53 ). A liquid repellent property on the transition area ( 53 ) is higher than a liquid repellent property of the first area (C 3 ), and is lower than a liquid repellent property of the second area (C 4 ). 
     Since the liquid repellent property of the transition area ( 53 ) is higher than the liquid repellent property of the first area (C 3 ), and is lower than the liquid repellent property of the second area (C 4 ), even when the liquid droplet is landed on the transition area ( 53 ), it is possible to move the liquid droplet toward a center of the first area (C 3 ) so that the center of the liquid droplet almost coincides with a center of the first area (C 3 ). 
     In the transferring body ( 3 ) of the present invention, the liquid repellent property of the transition area ( 53 ) may increase progressively at positions away from the center of the first area (C 3 ). In this case, even when the liquid droplet is adhered to the transition area ( 53 ), the liquid droplet moves toward the center of the first area (C 3 ) Accordingly, a position shift in the final adhering position of the liquid droplet on the transferring body ( 3 ) hardly occurs, and the printing quality is improved. 
     In the transferring body ( 3 ) of the present invention, in the transition area ( 53 ), a lyophilic area ( 50 ) and a liquid repellent area ( 52 ) may exist in a mixed manner. In this case, it is possible to make the liquid repellent property of the transition area ( 53 ) higher than the liquid repellent property of the first area (C 3 ), and lower than the liquid repellent property of the second area (C 4 ). 
     In the transferring body ( 3 ) of the present invention, in the transition area ( 53 ), a proportion of an area of the liquid repellent area ( 51 ) with respect to an area of the lyophilic area ( 50 ) may increase progressively at positions away from the center of the first area (C 3 ). In this case, in the transition area ( 53 ), it is possible to increase gradually the liquid repellent property at positions away from the center of the first area (C 3 ). 
     In the transferring body ( 3 ) of the present invention, in the transition area ( 53 ), a boundary ( 52 ) between the lyophilic area ( 50 ) and the liquid repellent area ( 51 ) may be formed to be serrated, and the lyophilic area ( 50 ) may be formed along a circumference of the first area (C 3 ) as a plurality of lyophilic areas ( 50   a ) projecting acutely toward the second area (C 4 ). In these cases, in the transition area ( 53 ), since the proportion of the area of the liquid repellent area ( 51 ) increases progressively at positions away from the center of the first area (C 3 ), it is possible to increase progressively the liquid repellent property at positions away from the center of the first area (C 3 ). 
     In the transferring body ( 3 ) of the present invention, in a transition area ( 63 ), lyophilic areas ( 62 ) may be arranged in a discrete manner in a liquid repellent area ( 61 ), and a distribution density of the lyophilic areas ( 62 ) may decrease progressively at positions away from the center of the first area (C 3 ). Even in this case, in the transition area ( 63 ), since a proportion of an area of the liquid repellent area ( 61 ) increases progressively at positions away from the center of the first area (C 3 ), it is possible to increase progressively the liquid repellent property at positions away from the center of the first area (C 3 ). 
     In the transferring body ( 3 ) of the present invention, the first area (C 3 ) may be formed of an aluminum alloy, the transition area ( 53 ) may be formed of a polyimide, and the second area (C 4 ) may be formed of a fluororesin. 
     According to a third aspect of the present invention, there is provided a printer ( 1 ) which performs printing on a recording medium (P) by discharging liquid droplets, including a liquid droplet discharging section ( 2 ) which has a plurality of discharge ports ( 15 ) and the transferring body ( 3 ) as defined in the second aspect. 
     By using the transferring body ( 3 ) as defined in the second aspect, even when the liquid droplet is landed on the transition area ( 53 ), it is possible to move the liquid droplet toward a center of the first area (C 3 ) so that the center of the liquid droplet almost coincides with a center of the first area (C 3 ). Accordingly, a printer in which a position shift of a final adhering position of a liquid droplet on the transferring body ( 3 ) hardly occurs can be provided. 
     In the printer ( 1 ) of the present invention, in the liquid droplet discharging section ( 2 ), the discharge ports ( 15 ) may be arranged in a predetermined direction, in the transferring body ( 3 ), the first area (C 3 ) may be formed as a plurality of first areas (C 3 ) and the first areas (C 3 ) may be arranged in the predetermined direction; and a spacing distance (P 1 ) between the discharge ports ( 15 ) in the predetermined direction may be same as a spacing distance (P 1 ) between the first areas (C 3 ) in the predetermined direction. In this case, since the liquid droplet is discharged from each of the discharge ports ( 15 ) to one of the corresponding first areas (C 3 ), the printing is performed assuredly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic structural view of a printer according to an embodiment of the present invention; 
         FIG. 2  is a plan view of an ink-jet head in  FIG. 1 ; 
         FIG. 3  is a cross-sectional view taken along a line III-III shown in  FIG. 2 ; 
         FIG. 4  is a cross-sectional view taken along a line IV-IV shown in  FIG. 2 ; 
         FIG. 5  is a cross-sectional view taken along a line V-V shown in  FIG. 2 ; 
         FIG. 6  is a plan view in which a part of a side surface of a transferring drum in  FIG. 5  is enlarged; 
         FIG. 7  is a block diagram showing a relationship of connection between a control unit, a driver IC, and a drive motor; 
         FIG. 8A ,  FIG. 8B , and  FIG. 8C  are diagrams showing a movement of an ink droplet which is adhered near a lyophilic area in  FIG. 6 , where  FIG. 8A  shows a case when a small droplet is jetted from a nozzle,  FIG. 8B  shows a case when a medium droplet is jetted from the nozzle, and  FIG. 8C  shows a case when a large droplet is jetted from the nozzle; 
         FIG. 9  is a plan view corresponding to  FIG. 6 , of a first modified embodiment; 
         FIG. 10  is a plan view corresponding to  FIG. 6 , of a second modified embodiment; 
         FIG. 11  is a plan view corresponding to  FIG. 6 , of a third modified embodiment; 
         FIG. 12  is a cross-sectional view corresponding to  FIG. 5 , of a fourth modified embodiment; 
         FIG. 13  is a cross-sectional view corresponding to  FIG. 5  of a fifth modified embodiment; and 
         FIG. 14  is a cross-sectional view corresponding to  FIG. 5  of a sixth modified embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An exemplary embodiment of the present invention will be described below while referring to the accompanying diagram. As shown in  FIG. 1 , a printer  1  includes an ink-jet head  2  (liquid droplet discharging section), a transferring drum  3  (transferring body), a plurality of paper transporting rollers  4 , an ink tank  5 , a frame  6 , and the like. The ink-jet head  2 , is a line head which is longer in a scanning direction (left and right direction in  FIG. 1 ), and jets (discharges) an ink supplied from the ink tank  5 , as ink droplets from a plurality of nozzles  15  (discharge ports) (refer to  FIG. 2 ) arranged in a scanning direction (left and right direction in  FIG. 1 ) on a lower surface of the ink-jet head  2 . The ink-jet head  2  makes the ink droplets adhere to a side surface (surface)  3   a  of the transferring drum  3  which has a circular cylindrical shape. Here, the term “side surface” of the circular cylindrical shaped transferring drum  3  means a round surface, which corresponds to a rectangle when the circular cylinder is unfolded (rolled out), of the transferring drum  3 . The transferring drum  3  is substantially circular cylindrical shaped having almost the same length as the ink-jet head  2  in the scanning direction, and is rotatably installed on the frame  6 . Moreover, the transferring drum  3  is rotated and driven by a drive motor  8  (refer to  FIG. 7 ), and as it will be described later, transfers ink droplets to a recording paper P (recording medium) by bringing in contact with the recording paper P, a portion of the surface  3   a  to which the ink droplets are adhered. The paper transporting rollers  4  rotate in synchronization with a rotating speed of the transferring drum  3 , and transport the recording paper P in a paper feeding direction (frontward direction in  FIG. 1 ). 
     Next, the ink-jet head  2  will be described by referring to  FIG. 2  to  FIG. 4 . As shown in  FIG. 2  to  FIG. 4 , the ink-jet head  2 , includes a channel unit  31  in which a plurality of individual channels including pressure chambers  10  is formed, and a piezoelectric actuator  32  which is arranged on an upper surface of the channel unit  31 . 
     The channel unit  31 , as shown in  FIG. 3  and  FIG. 4  includes a cavity plate  20 , a base plate  21 , a manifold plate  22 , and a nozzle plate  23 , and is formed by stacking these four plates. From among the four plates  20  to  23 , the three plates  20  to  22  except for the nozzle plate  23 , are formed of a metallic material such as stainless steel, and the ink channels such as the pressure chambers  10  and manifold channels  11  are formed by an etching. The nozzle plate  23  is formed of a synthetic resin material such as polyimide, and is stuck to a lower surface of the manifold plate  22 . Or, the nozzle plate  23 , similar to the three plates  20  to  22  may also be formed of a metallic material. 
     The plurality of pressure chambers  10  (16 pieces in  FIG. 2 ) which are arranged in two rows in the scanning direction (vertical direction in  FIG. 2 ) is formed in the cavity plate  20  as shown in  FIG. 2  to  FIG. 5 . The pressure chambers  10  are substantially elliptical shaped with a longitudinal axis of the elliptical shape in the paper feeding direction in a plan view. 
     A plurality of communicating holes  12  and  13  having a substantially circular shape in a plan view is formed in the base plate  21 , in a portion overlapping with both ends in the longitudinal direction, of the pressure chambers  10  respectively. 
     A manifold channel  11  which is extended in the scanning direction is formed in the manifold plate  22 . The manifold channel  11  overlaps with a substantial right half portion of the pressure chambers  10  arranged on a right side in  FIG. 2  in a plan view, and also overlaps with a substantial left half portion of the pressure chambers  10  arranged on a left side in  FIG. 2  in a plan view. An ink is supplied to the manifold channel  11  from an ink supply port  9  which is formed in a vibration plate  40  which will be described later. Moreover, a plurality of communicating holes  14  having a substantially circular shape in a plan view is formed at portions overlapping with the communicating holes  13  in a plan view. 
     A plurality of nozzles  15  is formed in the nozzle plate  23 , at positions overlapping with the communicating holes  14  in a plan view. The nozzles  15  are arranged at equal intervals in two rows in the scanning direction, corresponding to the pressure chambers  10 , and as shown in  FIG. 2 , an interval between two nozzles  15  at the nearest position with respect to the scanning direction is P 1 . Here, when the nozzle plate  23  is formed of a synthetic resin material, it is possible to form the nozzles  15  by a process such as an excimer laser process, and when the nozzle plate  23  is formed of a metallic material, it is possible to form the nozzles  15  by a process such as a press processing. 
     The manifold channel  11  communicates with the pressure chambers  10  via the communicating holes  12 . Furthermore, the pressure chambers  10  communicate with the nozzles  15  via the communicating holes  13  and  14 . Thus, individual ink channels from the manifold channel  11  up to the nozzles  15  via the pressure chambers  10  are formed in the channel unit  31 . 
     Next, the piezoelectric actuator  32  will be described below. The piezoelectric actuator  32 , as shown in  FIG. 2  to  FIG. 4 , includes the vibration plate  40  which is electroconductive, and is arranged on a surface of the cavity plate  20 , a piezoelectric layer  41  which is formed on an upper surface of the vibration plate  40 , and a plurality of individual electrodes  42  which are formed corresponding to the pressure chambers  10 , on an upper surface of the piezoelectric layer  41 . 
     The vibration plate  40  is made of a metallic material, such as an iron alloy like stainless steel, a nickel alloy, an aluminum alloy, or a titanium alloy, and is joined to the cavity plate  20  to cover the pressure chambers  10 . Moreover, the vibration plate  40  is electroconductive, and also serves as a common electrode which generates an electric field in the piezoelectric layer  41  which is sandwiched between the vibration plate  40  and the individual electrodes  42 . The vibration plate  40  is kept all the time at a ground electric potential by a driver IC  45  (refer to  FIG. 7 ). 
     In an area excluding an area near a lower end portion of the channel unit  31  in  FIG. 2  on the upper surface of the vibration plate  40 , the piezoelectric layer  41  composed of mainly lead zirconate titanate (PZT) which is a solid solution of lead titanate and lead zirconate is formed continuously spreading over the pressure chambers  10 . Here, the piezoelectric layer  41  is formed by an aerosol deposition method (AD method) in which, ultra fine particles of a piezoelectric material are deposited on the upper surface of the vibration plate  40  by allowing to collide at a high speed. Apart from this, it is also possible to use a sol-gel method, a sputtering method, a hydrothermal synthesis method, and a chemical vapor deposition method (CVD method) for forming the piezoelectric layer  41 . Or, it is also possible to form the piezoelectric layer  41  by sticking on the upper surface of the vibration plate  40 , a piezoelectric sheet which is obtained by baking a green sheet of PZT. 
     The plurality of individual electrodes  42  is formed on the upper surface of the piezoelectric layer  41 , corresponding to the plurality of pressure chambers  10  as shown in  FIG. 2  to  FIG. 4 . The individual electrode  42 , as shown in  FIG. 2 , has a substantial elliptical shape slightly smaller than the pressure chamber  10 , and is positioned to overlap with a substantial central portion of the pressure chamber  10  in a plan view. Moreover, the individual electrode  42  is extended in a longitudinal direction of the pressure chamber  10  up to a portion on a side opposite to the nozzle  15 , and a contact point  42   a  is formed on the portion not overlapping with the pressure chamber  10  in a plan view. Further, the individual electrode  42  is connected to the driver IC  45  (refer to  FIG. 7 ) at the contact point  42   a , via a flexible printed circuit (FPC) which is not shown in the diagram, and an electric potential of the plurality of individual electrodes is controlled by the driver IC  45 . Here, the individual electrode  42  is made of an electroconductive material such as gold, copper, silver, palladium, and titanium, and it is possible to form the individual electrode  42  by a method such as a screen printing method and the sputtering method. 
     The driver IC  45  (refer to  FIG. 7 ) keeps the vibration plate  40  serving as the common electrode, at a ground electric potential, and is capable of applying three types of predetermined electric potentials to the individual electrode  42 . The driver IC  45  controls the electric potential to be applied to the individual electrode  42 , and as it will be described later, controls an action of the piezoelectric actuator  32 . Moreover, the driver IC  45 , as it will be described later, is controlled by a control unit  46  (refer to  FIG. 7 ), so as to apply the electric potential to the individual electrode  42  at a predetermined timing. 
     Next, an action of the piezoelectric actuator  32  will be described below. When a predetermined electric potential is applied to the individual electrode  42  by the driver IC  45 , an electric potential difference is developed in a portion sandwiched between the individual electrode  42  to which the predetermined electric potential is applied and the vibration plate  40  which serves as the common electrode. Consequently, an electric field in direction of thickness is generated in this portion of the piezoelectric layer  41 . Accordingly, when a direction in which the piezoelectric layer  41  is polarized is the direction of thickness same as the direction of the electric field, this portion of the piezoelectric layer  41  is contracted in a horizontal direction which is orthogonal to the direction of thickness. With the contraction of the piezoelectric layer  41 , the vibration plate  40  is deformed to form a projection downward, and a volume of the pressure chamber  10  is decreased. Consequently, a pressure on the ink in the pressure chamber  10  is increased, and an ink droplet is jetted from the nozzle  15  which communicates with the pressure chamber  10 . 
     Here, the driver IC  45 , as it has been described earlier, is capable of applying the three types of electric potentials to the individual electrode  42 , as the predetermined electric potential. Further, when the electric potential applied to the individual electrode  42  is changed, an amount of deformation of the vibration plate  40  is changed. Therefore, a volume of the ink droplet jetted from the nozzle  15  changes according to the electric potential applied to the individual electrode  42 . In other words, in the ink-jet head  2 , it is possible to perform a liquid-droplet gradation which jets three types of ink droplets each having different volume (hereinafter, a small droplet I 1 , a medium droplet I 2 , and a large droplet I 3  in an ascending order of volume (refer to  FIG. 8 )) from the nozzle  15 . 
     Next, the transferring drum  3  will be described by referring to  FIG. 5  and  FIG. 6 . As shown in  FIG. 5 , the transferring drum  3  is positioned under the ink-jet head  2 , and is capable of rotating in a clockwise direction in  FIG. 5 . Moreover, a portion of the transferring drum  3 , which is positioned at an uppermost side of the side surface  3   a , is facing the nozzle  15 . Accordingly, an ink droplet I jetted from the nozzle  15  is adhered to a portion of the side surface  3   a  facing the nozzle  15 . 
     On the other hand, a supporting roller  7  is arranged under the transferring drum  3 , and a recording paper P is pinched between the transferring drum  3  and the supporting roller  7 . Further, the transferring drum  3  is rotated in the clockwise direction in  FIG. 5  by the drive motor  8  (refer to  FIG. 7 ) and the supporting roller  7  is rotated in a counterclockwise direction. Accordingly, the portion of the side surface  3   a  to which the ink droplet I is adhered comes in contact with the recording paper P, and the ink droplet I is transferred to the recording paper P, and the recording paper P is transported in the paper feeding direction (left side direction in  FIG. 5 ). Accordingly, printing is performed on the recording paper P. 
     As shown in  FIG. 6 , a plurality of lyophilic areas  50  and a liquid repellent area  51  surrounding the lyophilic areas  50 , having a liquid repellent property higher than a liquid repellent property of the lyophilic areas  50  are formed on the side surface  3   a  of the transferring drum  3 . In the present invention, the term “liquid repellent area” means an area in which a wetting angle with respect to the ink droplet is larger than a wetting angle in the lyophilic area. It is desirable that the wetting angle in the liquid repellent area is larger than that in the lyophilic area  50  by at least 10 degrees in order to make the ink droplet move smoothly toward the center of the lyophilic area  50 . In this embodiment, it is allowable that the wetting angle of the liquid repellent area is not less than 60 degrees, and that the wetting angle of the lyophilic area is not more than 50 degrees. The lyophilic areas  50  are arranged at fixed intervals in the scanning direction (vertical direction in  FIG. 6 ) and in a circumferential direction (left and right direction in  FIG. 6 ) of the transferring drum  3 . The interval (spacing distance) between the adjacent lyophilic areas  50 , with respect to the scanning direction is P 1  which is same as the spacing distance between the nozzles  15  (refer to  FIG. 2 ) with respect to the scanning direction described earlier. Moreover, on the side surface  3   a , the area surrounding the lyophilic areas  50  other than the portion in which the lyophilic areas  50  are formed are the liquid repellent area  51 . 
     Moreover, the circumference (boundary line)  52  between the lyophilic area  50  and the liquid repellent area  51  is formed over the entire circumference of the lyophilic area  50 , in a serrated form bent alternately at a fixed angle, on a circle C 1  having a radius r 11  making a center same as a center of the lyophilic area  50 , and on a circle C 2  which is concentric with the circle C 1  and which has a radius r 12  (&gt;r 11 ). An area in a form of a ring which is a circumferential area  53  between the lyophilic area  50  and the liquid repellent area  51 , is defined by these circles C 1  and C 2 . In other words, an inner side (first area) C 3  of the circle C 1  is an area which is formed by only the lyophilic area  50 , and an outer side (second area) C 4  of the circle C 2  is an area which is formed by only the liquid repellent area  51 , and the circumferential area  53  is an area (transition area) in which the lyophilic area  50  and the liquid repellent area  51  exist in a mixed manner. Consequently, an average liquid repellent property of the circumferential area  53  is higher than the liquid repellent property of the lyophilic area  50  and lower than the liquid repellent property of the liquid repellent area  51 . Moreover, in the lyophilic area  50  in the circumferential area  53 , a plurality of projections  50   a  in a form of an acute angle pointing toward an outer side of a radial direction of the circle C 1 , in other word toward the liquid repellent area  51 , is formed in a pattern arranged at an equal interval over the entire circumference of the circle C 1 . Accordingly, in the circumferential area  53 , a proportion of the liquid repellent area  51  with respect to an area of the lyophilic area  50  is increased progressively at positions away from the center of the lyophilic area  50 , and the liquid repellent property is improved gradually, at positions away from the center of the lyophilic area  50 . On the other hand, a volume of the ink droplet I which is jetted from the nozzle  15  is adjusted such that a radius of an area on the side surface  3   a  to which the ink droplet I is adhered (hereinafter, called as only “radius”) is not less than r 11 , and not more than r 12  when viewed from a direction orthogonal to the side surface  3   a . Consequently, even when the ink droplet I jetted from the nozzle  15  is landed on the circumferential area  53 , it is possible to move the ink droplet I toward the center of the lyophilic area  50  such that the center of the ink droplet I almost coincides with the center of the lyophilic area  50 . Furthermore, in a case of performing a liquid droplet gradation, by adjusting the volume of the ink droplet I such that the radius is not less than r 11  and not more than r 12 , a position shift in the final adhering position of the ink droplet I with respect to the side surface  3   a  of the transferring drum  3  does not occur, and it is possible to maintain a favorable printing quality. In the embodiment of the present invention, the radius of the small droplet I 1  and the radius of the large droplet I 3  (refer to  FIG. 8 ) are r 11  and r 12  respectively, and the radius of the medium droplet I 2  (refer to  FIG. 8 ) is greater than the diameter r 11  and smaller than the diameter r 12 . Here, for example, when a ratio of r 11  and r 12  is let to be 1:2, since a ratio of volumes becomes 1 3 :2 3 =1:8, a liquid droplet gradation can be performed such that the ratio of the volume of the small droplet I 1  with the volume of the large droplet I 3  becomes 1:8. 
     For forming such lyophilic area  50  and the liquid repellent area  51 , a liquid repellent film made of fluororesin is formed on the side surface  3   a  of the transferring drum  3 . Moreover, a mask may be formed leaving a portion in which the lyophilic area  50  is formed on the side surface  3   a  of the transferring drum  3 , and by irradiating an excimer laser or the like, the liquid repellent film on a portion in which the mask is not formed, may be removed. Accordingly, the portion from which the liquid repellent film is removed becomes the lyophilic area  50 , and the portion on which the liquid repellent film is remained becomes the liquid repellent area  51 . 
     Here, an operation of the driver IC  45  which controls the piezoelectric actuator  32 , and the drive motor  8  which rotates the transferring drum  3  is controlled by the control unit  46  as shown in  FIG. 7 . The control unit  46 , at the time of performing printing, controls the operation of the driver IC  45  and the drive motor  8  such that an ink droplet is jetted from the nozzle  15  when a center of the lyophilic area  50  on the side surface  3   a  of the transferring drum  3  shown in  FIG. 6  reaches an uppermost portion in  FIG. 5 . Accordingly, at least a part of the ink droplet jetted from the nozzle  15  is adhered to the corresponding lyophilic area  50 . 
     Next, a printing operation in the printer  1  will be described by referring to  FIG. 5  to  FIG. 8C . As shown in  FIG. 8A , when the small droplet I 1  jetted from the nozzle  15  is adhered spreading across the circumference (boundary line)  52  between the lyophilic area  50  and the liquid repellent area  51 , in the circumferential area  53 , the liquid repellent property of is declined progressively toward the center of the lyophilic area  50 . Therefore, the small droplet I 1  moves toward the center of the lyophilic area  50  which has low liquid repellent property. Finally, the small droplet I 1  moves till a center of the small droplet I 1  almost coincides with the center of the lyophilic area  50 . 
     Similarly, as shown in  FIG. 8B  and  FIG. 8C , even when the medium droplet I 2  and the large droplet I 3  are jetted from the nozzle  15 , the medium droplet I 2  and the large droplet I 3  move toward the center of the lyophilic area  50  till the center of the medium droplet I 2  and the center of the large droplet I 3  almost coincide with the center of the lyophilic area  50 . 
     The movement of the ink droplet mentioned above is completed in a time after the ink droplet is adhered to the side surface  3   a  of the transferring drum  3  till the ink droplet adhered to the side surface  3   a  is transferred to the recording paper P upon rotation of the transferring drum  3 . Accordingly, the ink droplet is transferred to an appropriate position on the recording paper P, and the printing quality is improved. 
     According to the embodiment described above, the circumference (boundary line)  52  between the lyophilic area  50  and the liquid repellent area  51  is formed to be serrated, over the entire circumference of the lyophilic area  50  in the circumferential area  53 . Consequently, the liquid repellent property on the circumferential area  53  between the lyophilic area  50  and the liquid repellent area  51  is gradually improved at positions away from the center of the lyophilic area  50 . Therefore, even when the ink droplet I jetted from the nozzle  15 , and having a size different from the size of the lyophilic area  50  is adhered spreading over the lyophilic area  50  and the liquid repellent area  51 , due to a shift in a landing position on the side surface  3   a  of the transferring drum  3 , it is possible to move the liquid droplet toward the center of the lyophilic area  50  having low liquid repellent property, till the center of the liquid droplet I almost coincides with the center of the lyophilic area  50 . Accordingly, there is no position shift in a final adhering position of the ink droplet I on the side surface  3   a  of the transferring drum  3 , and the ink droplet I is transferred to an appropriate position on the recording paper P. Therefore, the printing quality is improved. 
     Moreover, even when the three types of ink droplets (small droplet I 1 , medium droplet I 2 , and large droplet I 3 ) of a mutually different volume are jetted from the nozzle  15 , it is possible to move the ink droplet I which is adhered to the side surface  3   a  of the transferring drum  3 , to the center of the lyophilic area  50 . Therefore, even when the liquid droplet gradation is performed, there is no position shift in the final adhering position of the ink droplet I with respect to the side surface  3   a  of the transferring drum  3 . 
     Moreover, the nozzles  15  are arranged at the interval P 1  with respect to the scanning direction, and the lyophilic areas  50  are arranged at the interval P 1  with respect to the scanning direction. Therefore, the ink droplet I jetted from the nozzle  15  is adhered to the corresponding lyophilic area  50 , and the printing is performed assuredly. 
     Moreover, upon rotation of the transferring drum  3 , when the lyophilic area  50  has reached a position facing the nozzle  15 , the ink droplet I is jetted from the nozzle  15 . Therefore, it is possible to make the ink droplet I adhere assuredly near the lyophilic area  50 . 
     Next, modified embodiments in which various modifications are made in the embodiment will be described below. Same reference numerals are assigned to components which are similar as in the embodiment, and the description to be repeated is omitted. 
     As shown in  FIG. 9 , a circumferential area  63  between a liquid repellent area  61  and a lyophilic area  60 , on the side surface  3   a  of the transferring drum  3  (refer to  FIG. 5 ), may be formed by scattering in the liquid repellent area  61 , a plurality of island portions  62  having a liquid repellent property almost same as a liquid repellent property of the lyophilic area. In this case, the island portions  62  may be arranged such that a distribution density of the island portions  62  decreases progressively at positions away from a center of the lyophilic area  60  (first modified embodiment). In this case also, in the circumferential area  63 , an average liquid repellent property is higher than the liquid repellent property of the lyophilic area  60  and lower than the liquid repellent property of the liquid repellent area  61 . Moreover, the liquid repellent property of the side surface  3   a  is improved progressively at positions away from the center of the lyophilic area  60 . Therefore, when a radius of the ink droplet is not less than a radius r 21  of the lyophilic area  60 , and is not more than a distance r 22  between the center of the lyophilic area  60  and an outermost portion of the island portion  62  arranged at an outermost side with respect to (of) the center of the lyophilic area, it is possible to move the ink droplet adhered to the side surface  3   a , toward the center of the lyophilic area  60 , till a center of the ink droplet almost coincides with the center of the lyophilic area  60 . It is possible to form such island portions  62  also in a portion in which the island portions  62  are formed, by irradiating the excimer laser without forming the mask. 
     As shown in  FIG. 10 , an intermediate area  72  having a liquid repellent property higher than a liquid repellent property of the lyophilic area  70 , and lower than a liquid repellent property of the liquid repellent area  71 , may be formed in a circumferential area  73  between the lyophilic area  70  and the liquid repellent area  71  (second modified embodiment). In this case, a circumferential area is formed by the intermediate area  72 , and a part of the lyophilic area  70  and a part of the liquid repellent area  71  in continuity with the intermediate area  72 , and an average liquid repellent property thereof is higher than the liquid repellent property of the lyophilic area  70  and lower than the liquid repellent property of the liquid repellent area  71 . Even in this case, the liquid repellent property of the side surface  3   a  of the transferring drum  3  gradually increases at positions away from a center of the lyophilic area  70 . Consequently, when the radius of the liquid droplet is not less than a radius r 31  of the lyophilic area  70 , and not more than a radius r 32  of an outermost portion of the intermediate area  72 , when the ink droplet is adhered spreading over the lyophilic area  70  and the liquid repellent area  71 , it is possible to move the ink droplet toward a center of the lyophilic area  70 , till the center of the liquid droplet almost coincides with the center of the lyophilic area  70 . Such intermediate area  72 , similarly as in the embodiment described above, can be formed as follows. First, after forming a mask in an area of the side surface  3   a  of the transferring drum  3 , excluding the area in which the lyophilic area  70  is formed, the lyophilic area  70  is formed by irradiating the excimer laser. Next, after forming a mask in an area of the side surface  3   a , excluding a portion in which the intermediate area  72  is formed, the intermediate area  72  is formed causing degradation of the liquid repellent film by irradiating the excimer laser. However, at the time of forming the intermediate area  72 , it is necessary to make a time of irradiating the excimer laser shorter than a time of irradiation for forming the lyophilic area  70 . Or, each of the lyophilic area  70 , the circumferential area  73 , and the liquid repellent area  71  may be formed of a different material. In this case, a polyimide film is formed on a side surface  3   a  made of aluminum alloy, of the transferring drum  3 , and a liquid repellent film made of a fluororesin is formed further on the polyimide film. Next, a mask is formed on an area of the side surface  3   a , excluding a portion on which the circumferential area  73  and the lyophilic area  70  are formed, and the fluororesin is removed by irradiating the excimer laser. Further, a mask is formed on an area of the side surface  3   a  excluding a portion on which the lyophilic area  70  is formed, and the polyimide film is removed by irradiating the excimer laser. Accordingly, a portion from which the liquid repellent film made of the polyimide film and the fluororesin film is removed, becomes the lyophilic area  70  formed of aluminum alloy, a portion from which the liquid repellent film made of the fluororesin is removed, becomes the circumferential area  73  formed of polyimide, and a portion on which the liquid repellent film of the fluororesin remains becomes the liquid repellent area  71 . The lyophilic area  70  may be formed by coating an alumina layer on the side surface  3   a  of the transferring drum  3  made of aluminum alloy with sputtering or the like. The liquid repellent area  71  may be formed by coating a nickel layer containing particles of fluororesin with composite plating, or by coating a silicone resin layer. 
     Moreover, as shown in  FIG. 11 , in a circumferential area between a lyophilic area  70  and a liquid repellent area  71 , a plurality (two in  FIG. 11 ) of intermediate areas  82  and  83  may be formed in a radial direction of the lyophilic area  70 . In this case, the intermediate area  83  which is provided on an outer side may have a liquid repellent property higher than a liquid repellent property of the intermediate area  82  which is provided on an inner side (the liquid repellent property of the plurality of intermediate areas may increase progressively at positions away from the center of the lyophilic area  70 ) (third modified embodiment). Even in this case, in the circumferential area, an average liquid repellent property thereof is higher than a liquid repellent property of the lyophilic area  80 , and lower than a liquid repellent property of the liquid repellent area  81 . Moreover, since the liquid repellent property of the side surface  3   a  of the transferring drum  3  gradually increases toward an outer side from the center of the lyophilic area  70 , it is possible to move assuredly the ink adhered to the side surface  3   a  toward a central portion of the lyophilic area  80 . The intermediate areas  82  and  83 , similarly as in the second modified embodiment, are formed causing degradation of the liquid repellent film by irradiating the excimer laser. However, at the time of forming the outer side intermediate area  83 , it is necessary to make a time of irradiating the excimer laser shorter than a time of irradiation for forming the inner side intermediate portion  82 . 
     As shown in  FIG. 12 , an arrangement may be made such that a plurality (four in  FIG. 12 ) of ink-jet heads  2  is arranged in a direction of rotation of the transferring drum  3 , and ink droplets of mutually different colors are jetted from the ink-jet heads  2  (fourth modified embodiment). In this case, the transferring drum  3  is rotated, and by jetting from the nozzle  15  when the lyophilic area  50  formed on the side surface  3   a  of the transferring drum  3  (refer to  FIG. 6 ) reaches a position facing the nozzle  15  of each ink-jet head  2  (refer to  FIG. 2 ), it is possible to perform printing of a plurality of colors (four colors in  FIG. 12 ). 
     A liquid droplet discharging section is not restricted to a liquid droplet discharging section of an ink-jet type. Instead of the ink-jet head  2 , for example, an ink transporting head (liquid droplet discharging section)  90  in which a common electrode  94  is formed on a surface of a manifold channel  91 , and an individual electrode  95  sandwiching a liquid repellent film  96  is formed on a surface near a discharge port  93  of an individual ink channel  92  which communicates with the manifold channel  91  may be arranged as shown in  FIG. 13  (fifth modified embodiment). In this case, when the common electrode  94  and the individual electrode  95  are at the same electric potential (ground electric potential for example), since the liquid repellent film  96  exists, the ink is not flowed to a portion of the individual ink channel  92  on which the liquid repellent film  96  is formed, and the ink does not flow out from the discharge port  93 . On the other hand, when there is an electric potential difference between the common electrode  94  and the individual electrode  95 , since the liquid repellent property of the liquid repellent film is declined (electrowetting phenomenon: refer to Japanese Patent Application Laid-open No. 2003-177219), the ink also flows to a portion in which the liquid repellent film  96  is formed, and the ink flows out from the discharge port  93 . Accordingly, it is possible to make the ink droplet adhere to the side surface  3   a  of the transferring drum  3  similarly as in the ink-jet head  2  in the embodiment. 
     Moreover, in the embodiment and the modified embodiments, although the transferring drum  3  is used as the transferring body, the transferring body is not restricted to the transferring drum  3 . For example, as shown in  FIG. 14 , a belt  30  which is wound around a driving pulley  30   b  and a driven pulley  30   c  may be used as the transferring body. The driving pulley  30   b  is positioned under the ink-jet head  2 , and is rotatable in a clockwise direction in  FIG. 14 . Moreover, the belt  30  faces the nozzle  15 , at an uppermost portion of the driving pulley  30 . The belt  30  put around the driving pulley  30   b  and the driven pulley  30   c  is rotated by the rotation of the driving pulley  30   b  which is rotated by the drive motor  8 , and the belt performs a circumferential movement in the clockwise direction in  FIG. 14 . In this case, similarly as in the embodiment and the modified embodiments, a lyophilic area, a liquid repellent area, and a circumferential area are formed on a surface  30   a  of the belt  30 . At the time of performing printing, by controlling the driver IC  45  and the drive motor  8  such that an ink droplet is jetted at a timing when a center of the lyophilic area formed on the surface  30   a  of the belt  30  reaches right under the nozzle  15 , it is possible to achieve an effect similar to an effect in the embodiment and the modified embodiments. A direction of rotation of the driving pulley  30   b  and the belt  30  may be a counterclockwise direction in  FIG. 14 . 
     In the abovementioned description, the circumference (boundary line) between the lyophilic area and the liquid repellent area is formed to be circular shaped or serrated along the circle. However, the shape of the circumference is not restricted to this, and it may have other shape such as a triangular shape, a rectangular shape, and an elliptical shape. 
     Moreover, in the abovementioned description, an example in which the present invention is applied to a printer which performs printing by transferring the ink droplet to the recording paper, is shown. However, the present invention is also applicable to other printers which transfer a liquid other than the ink, to a printing medium. It is also possible to apply the present invention to a printer which forms a wiring pattern by transferring to a substrate, an electroconductive liquid in which metallic nano particles are dispersed, a printer which manufactures a DNA chip by using a solution in which DNA is dispersed, and a printer which manufactures a color filter for liquid crystal display by using a liquid in which pigments for the color filter are dispersed.