Patent Publication Number: US-10759170-B2

Title: Ink jet printing apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2018-13148, filed on Jan. 30, 2018 and Japanese Patent Application No. 2019-9837, filed on Jan. 24, 2019. The above applications are hereby expressly incorporated by reference, in its entirety, into the present application. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is related to an ink jet printing apparatus having an ink jet head for ejecting ink. 
     Ink jet printing apparatuses that eject ink from an ink jet head to administer printing on print media such as paper and film have been proposed. Utilizing such ink jet printing apparatuses to perform printing processes on base materials such as building materials and decorative panels has also been proposed. 
     There are some print media for printing by ink jet printing apparatuses, which are curved or have protrusions and recesses on the surfaces thereof. When printing is performed on such a print medium, there is a possibility that an ink ejection surface of an ink jet head, at which the tip of a nozzle is exposed, will contact the print medium, because the distance between the print medium and the ink jet head varies depending on the printing position of the print medium. 
     In the case that the print medium contacts the ink ejection surface, an ink repellent film which is formed on the ink ejection surface may be damaged. If the ink repellent film is damaged, it will become more likely for ink to adhere to the ink ejection surface, and there is a possibility that the adhered ink will cause ejection failure of the ink from the nozzle, which may decrease print image quality. 
     Therefore, providing a protective member called a nozzle guard to protect the surface of an ink ejection surface of an ink jet head has been proposed (Japanese Unexamined Patent Publication No. 2016-74176, for example). 
     In ink jet printing apparatuses, ink or dust such as paper dust, which is generated from paper sheets, may adhere to an ink ejecting port of a nozzle. In the case that ink adheres to or paper dust accumulates on the ink ejecting port of the nozzle, ejection defects such as irregularities in the ejection direction of ink from the nozzle or ejection failure may occur. 
     Performing a series of operations for forcibly ejecting ink from a nozzle of an ink jet head, that is, performing a so called purge, and then wiping an ink ejecting port of the nozzle with a wipe blade, is a known procedure for reducing such ejection defects. By performing this procedure, the wipe blade removes ink which is adhered to the ink ejecting port of the nozzle as well as dust from the ink ejecting port of the nozzle. 
     For example, Japanese Unexamined Patent Publication No. 2016-32930 proposes an apparatus that performs a wiping operation by moving a wipe blade from a first short side to a second short side that faces the first short side of a rectangular ink ejection surface. 
     SUMMARY OF THE INVENTION 
     Here, some ink jet heads having the aforementioned nozzle guard have gaps between an ink ejection surface and the nozzle guard. In the case that the aforementioned purging and wiping operations are performed in such an ink jet head, a portion of ink which is adhered to the ink ejection surface may enter the gap between the ink ejection surface and the nozzle guard. 
     It is extremely difficult to remove ink which has entered the gap by a wiping operation. As disclosed in Japanese Unexamined Patent Publication No. 2016-32930 for example, when the wiping operation is performed by moving the wipe blade from the first short side to the second short side of the rectangular ink ejection surface, although it may be possible to remove ink from a gap on the first short side, it is difficult to remove the ink from the gaps at the remaining three sides of the rectangular ink ejection surface. 
     In addition, in the case of a system that performs a printing process while moving the ink jet head, during the printing process, there is a possibility that ink which has entered a gap will move to the side of the opening of a nozzle guard and block the ink ejecting port of a nozzle due to the movement of the ink jet head, resulting in ejection failure. 
     Further, during a standby state in which a printing process is not being performed, an opening of a nozzle guard is sealed by a cap to prevent the tip of a nozzle from drying. However, there is a possibility that ink which has entered a gap will move to the side of the opening of the nozzle guard and block the ink ejecting port of the nozzle by repeating opening and closing operations of the cap, resulting in ejection failure. 
     Japanese Patent No. 6147582 discloses a method for suppressing ink within a gap between a nozzle guard and an ink ejection surface from seeping out onto the ink ejection surface, by weakening the pressure by which the cap is pressed against the ink jet head when maintenance is performed by suctioning ink with the aforementioned cap. 
     However, because the method disclosed in Japanese Patent No. 6147582 is not a method for directly removing the ink in the gap between the nozzle guard and the ink ejection surface, there is a possibility that the ink within the gap will move onto the ink ejection surface due to movement of an ink jet head to block an ink ejecting port of a nozzle, resulting in ejection failure. 
     The present invention has been developed in view of the foregoing circumstances. It is an object of the present invention to provide an ink jet printing apparatus capable of removing ink in a gap between a nozzle guard and an ink ejection surface, and suppressing ejection failure caused by movement of an ink jet head. 
     An ink jet printing apparatus of the present invention comprises: 
     an ink jet head having a nozzle row in which a plurality of nozzles for ejecting ink are arranged and a nozzle guard with an opening at a portion corresponding to the nozzle row, provided at a position via a gap with respect to an ink ejection surface of the nozzle row; 
     a sheet shaped absorbing member having a size that covers a range of the opening of the nozzle guard; and 
     a pressing mechanism for pressing the absorbing member onto the opening of the nozzle guard. 
     The ink jet printing apparatus of the present invention is provided with the sheet shaped absorbing member having a size that covers the range of the opening of the nozzle guard of the ink jet head, and the absorbing member is pressed onto the opening of the nozzle guard by the pressing mechanism. Therefore, ink in the gap between the nozzle guard and the ink ejection surface can be removed. Accordingly, even in the case that the ink jet head is moved, it is possible to suppress ejection failure caused by movement of the ink jet head. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view that illustrates the schematic configuration of an embodiment of an ink jet printing apparatus of the present invention. 
         FIG. 2  is a diagram that illustrates the schematic configuration of a shuttle unit. 
         FIG. 3  is a perspective view that illustrates the outer appearance of an ink jet head. 
         FIG. 4  is a diagram that illustrates a portion of a cross section of the ink jet head illustrated in  FIG. 3  taken along line A-A of  FIG. 3 . 
         FIG. 5  is a diagram that illustrates the schematic configuration of a capping unit. 
         FIG. 6  is a diagram that illustrates an example of an absorbing member 
         FIG. 7  is a diagram that illustrates the schematic configuration of a maintenance unit. 
         FIG. 8  is a diagram that illustrates the schematic configuration of an ink supply system and an ink suction system for an ink jet head. 
         FIG. 9  is a block diagram that illustrates a control system of the ink jet printing apparatus illustrated in  FIG. 1 . 
         FIG. 10A  is a diagram for explaining a maintenance operation performed by one embodiment of the ink jet printing apparatus of the present invention. 
         FIG. 10B  is a diagram for explaining a maintenance operation performed by one embodiment of the ink jet printing apparatus of the present invention. 
         FIG. 10C  is a diagram for explaining a maintenance operation performed by one embodiment of the ink jet printing apparatus of the present invention. 
         FIG. 11A  is a diagram for explaining a maintenance operation performed by one embodiment of the ink jet printing apparatus of the present invention. 
         FIG. 11B  is a diagram for explaining a maintenance operation performed by one embodiment of the ink jet printing apparatus of the present invention. 
         FIG. 11C  is a diagram for explaining a maintenance operation performed by one embodiment of the ink jet printing apparatus of the present invention. 
         FIG. 12  is a diagram that illustrates an example in which an elastic member is provided between a capping unit and an absorbing member. 
         FIG. 13  is a diagram that illustrates the schematic configuration of another embodiment of a pressing mechanism of the present invention. 
         FIG. 14  is a cross sectional view of the pressing member illustrated in  FIG. 13  taken along line B-B. 
         FIG. 15A  is a collection of diagrams for explaining an alternate embodiment of the maintenance operation. 
         FIG. 15B  is a collection of diagrams for explaining an alternate embodiment of the maintenance operation. 
         FIG. 15C  is a collection of diagrams for explaining an alternate embodiment of the maintenance operation. 
         FIG. 16D  is a collection of diagrams for explaining the alternate embodiment of the maintenance operation. 
         FIG. 16E  is a collection of diagrams for explaining the alternate embodiment of the maintenance operation. 
         FIG. 17  is a diagram for explaining seepage of ink from gaps in a nozzle guard. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, an embodiment of an ink jet printing apparatus of the present invention will be described in detail with reference to the attached drawings. The characteristic features of the ink jet printing apparatus of the present embodiment lie in a maintenance mechanism of an ink jet head and the manner of control thereof. First, the configuration of the entire ink jet printing apparatus will be described. FIG. is a perspective view that illustrates the schematic configuration of an ink jet printing apparatus  1  of the present embodiment. Note that in the description of the embodiment to follow, In the description of the embodiments described below, the up, down, left, right, front, and back directions indicated by arrows in  FIG. 1  are defined as the upper, lower, left, right, front, and back directions of the ink jet printing apparatus  1 . 
     As illustrated in  FIG. 1 , the ink jet printing apparatus  1  of the present embodiment is equipped with a shuttle base unit  2 , a flatbed unit  3 , and a shuttle unit  4 . 
     The shuttle base unit  2  supports the shuttle unit  4  and moves the shuttle unit  4  in the front-back direction (sub scanning direction). Specifically, the shuttle base unit  2  is equipped with a gantry section  11  and a sub scanning drive motor  12  (refer to  FIG. 9 ). 
     The gantry section  11  is formed in the shape of a rectangular frame and supports the shuttle unit  4 . Sub scanning drive guides  13 A and  13 B that extend in the front-back direction are respectively formed above the left and right sides of the frame of the gantry section  11 . The sub scanning drive guides  13 A and  13 B guide the shuttle unit  4  so as to move in the front-back direction. The sub scanning drive motor  12  moves the shuttle unit  4  in the front-back direction. 
     The flat bed unit  3  supports a print medium  15  such as a building material or a decorative panel. The flat bed unit  3  is arranged in a rectangular parallelepiped shaped recess formed inside the gantry section  11  of the shuttle base unit  2 . The flat bed unit  3  has a medium mounting surface  3   a , which is a horizontal surface on which the print medium  15  is placed. The flat bed unit  3  has an elevating mechanism that includes a hydraulic drive mechanism (not shown) or the like such that the height of the medium mounting surface  3   a  can be adjusted. 
     The shuttle unit  4  performs printing processes on the print medium  15 .  FIG. 2  is a diagram that illustrates the schematic configuration of the shuttle unit  4 . As illustrated in  FIG. 2 , the shuttle unit  4  is equipped with a casing  21 , a main scanning drive guide  22 , a main scanning drive motor  23  (refer to  FIG. 9 ), a head elevating guide  24 , a head elevating motor  25  (refer to  FIG. 9 ), a head unit  26 , a capping unit  66 , a suction unit  28 , an absorption member setting mechanism  29 , and a maintenance unit  30 . 
     The casing  21  accommodates components such as the head unit  26 . The casing  21  is formed in a portal shape so as to straddle the flatbed unit  3  in the left-right direction. The casing  21  is supported by the gantry portion  11  of the shuttle base unit  2  and is configured to be movable along the sub scanning drive guides  13  A and  13 B. 
     The main scanning drive guide  22  guides the head unit  26  so as to move in the left-right direction (main scanning direction). The main scanning drive guide  22  is formed by an elongated member that extends in the left-right direction. The head unit  26  is moved in the left-right direction by the main scanning drive motor  23 . 
     The head elevating guide  24  guides the head unit  26  to move in the up-down direction. The head elevating guide  24  is formed by a member having a shape which is elongated in the up-down direction. The head elevating guide  24  is configured to be movable in the left-right direction along the main scanning drive guide  22  together with the head unit  26 . The head unit  26  is moved up and down in the up-down direction by the head elevating motor  25 . 
     The head unit  26  performs printing processes by ejecting ink onto the print medium  15  while moving in the left-right direction along the main scanning drive guide  22  in the manner described above. As illustrated in  FIG. 2 , the head unit  26  has four ink jet heads  31 . 
       FIG. 3  is a perspective view that illustrates the outer appearance of an ink jet head  31 , and  FIG. 4  is a diagram that illustrates a portion of the cross section of the ink jet head  31  taken along line A-A of  FIG. 3 . 
     As illustrated in  FIG. 3 , the ink jet head  31  is equipped with a nozzle plate  36  and a nozzle guard  32 . The nozzle plate  36  has a nozzle row in which a plurality of ink ejecting ports  37  of nozzles that eject ink are arranged in the front-back direction. 
     As illustrated in  FIGS. 3 and 4 , the nozzle guard  32  has an opening  46  at a portion that corresponds to the nozzle row of the nozzle plate  36 , and is provided at a position via a gap  40  with respect to an ink ejection surface  36   a  of the nozzle row. In the present embodiment, the ink ejection surface  36   a  is the same surface as the surface of the nozzle plate  36 . 
     The nozzle guard  32  protects the ink ejection surface  36   a  of the nozzle plate  36 . Specifically, the nozzle guard  32  has a bottom plate  41  formed so as to cover the periphery of the nozzle row, and a side wall  42  erected on the peripheral edge of the bottom plate  41 . The aforementioned opening  46  is formed in the bottom plate  41 , and the gap  40  is formed between the bottom plate  41  and the ink ejection surface  36   a . The opening  46  is formed in a rectangular shape which is elongated in the front-back direction and is formed so as to expose the ink ejecting ports  37  of all of the nozzles. 
     The four ink jet heads  31  are arranged in parallel in the left-right direction. The four ink jet heads  31  eject inks of different colors (for example, cyan, black, magenta, and yellow). 
     The capping unit  66  seals the opening  46  of the nozzle guard  32  in order to prevent the ink ejecting ports  37  of the nozzles from drying while the ink jet printing apparatus  1  is not performing a printing process and is in a standby state. In the present embodiment, the capping unit  66  corresponds to a pressing mechanism of the present invention. 
     The capping unit  66  is installed within the right end portion of the casing  21  as illustrated in  FIG. 2 . When the head unit  26  moves to a standby position at the right end portion of the casing  21 , the opening  46  of the nozzle guard  32  is hermetically sealed. 
     As illustrated in  FIG. 5 , the capping unit  66  is equipped with a cap  71  (corresponding to a cap member of the present invention) and a cap base  72 . The cap  71  has an ellipsoid bottom portion  76  and a peripheral wall  77  erected from the peripheral edge of the bottom portion  76 . A suction aperture  78  for suctioning ink which is absorbed by an absorbing member  50 , which will be described later, is formed in the bottom portion  76 . A suction pipe  68  of a suction unit  28  to be described later is connected to the suction hole  78 . The cap base  72  is a base on which the cap  71  is formed. 
     The capping unit  66  is moved vertically in the up-down direction by a cap elevating motor  67  (refer to  FIG. 9 ). More specifically, the capping unit  66  moves vertically between a contact position at which the peripheral wall  77  of the cap  71  contacts the nozzle guard  32  and a retracted position below the contact position. 
     Further, when removing ink which has entered the aforementioned gap  40  formed between the bottom plate  41  of the nozzle guard  32  and the ink ejection surface  36   a , the capping unit  66  moves upward to the side of the ink jet head  31  in a state with the absorbing member  50  installed above the cap  71 , and presses the absorbing member  50  onto the opening  46  of the nozzle guard  32 . 
     The absorbing member  50  is a sheet shaped member having a size that covers the range of the opening  46  of the nozzle guard  32 , and is a water absorbent member.  FIG. 6  is a perspective view that illustrates the schematic configuration of the absorbing member  50 . Specifically, the length L 3  of the absorbing member  50  is greater than or equal to the length L 1  of the opening  46  of the nozzle guard  32  illustrated in  FIG. 3  in the front-back direction (the arrangement direction of the ink ejecting ports  37  of the nozzles), and the length L  4  is greater than or equal to the length L 2  of the opening  46  of the nozzle guard  32  in the left-right direction (the direction orthogonal to the arrangement direction of the ink ejecting ports  37  of the nozzles). A surface  50   a  of the absorbing member  50  illustrated in  FIG. 6  is pressed onto the opening of the nozzle guard  32 . 
     The material of the absorbing member  50  may be any material as long as it can absorb ink, but it is preferably a porous sheet. In the case that ink absorbed by the absorbing member  50  is suctioned by the suction unit  28 , it is preferable for the porous sheet to be that having continuous open cells as in the present embodiment. By employing a porous sheet having continuous open cells, suction of ink by the suction unit  28  can be conducted smoothly. Further, a printing sheet having porosity may be employed as the absorbing member  50 . 
     In the present embodiment, the absorbing member  50  is provided between each ink jet head  31  and each capping unit  66 , which is provided corresponding to each ink jet head  31 . 
     The absorbing member setting mechanism  29  is a mechanism for inserting and removing the absorbing member  50  between each ink jet head  31  and each capping unit  66 , which is provided corresponding to each ink jet head  31 . Specifically, the absorbing member setting mechanism  29  moves the absorbing member  50  between a cleaning position (the position illustrated in  FIG. 2 ), in which the absorbing member  50  is inserted between the ink jet head  31  and the capping unit  66 , and a retracted position, in which the absorbing member  50  is withdrawn from between ink jet head  31  and the capping unit  66 . The absorbing member setting mechanism  29  is configured by employing a known actuator or the like. 
     The suction unit  28  suctions ink which is absorbed by the absorbing member  50 . As illustrated in  FIG. 2 , the suction unit  28  is provided under the capping unit  66 . The suction unit  28  is equipped with four suction pipes  68 , four suction pumps  69 , and a waste liquid tank  70 . 
     One end of each of the four suction pipes  68  is connected to one of the suction apertures  78  which are formed in the bottom portion  76  of each of the four caps  71 , and the other ends of the four suction pipes  68  are connected to the waste liquid tank  70 . A suction pump  69  is provided for each suction tube  68 . 
     Ink which is absorbed by the absorbing member  50  that is set on the four caps  71  flows into the suction apertures  78  of the respective caps  71  by suction of the suction pump  69  and is stored in the waste liquid tank  70  via each suction pipe  68 . 
     The maintenance unit  30  cleans the ink ejection surface  36   a  of the ink jet head  31  and the lower surface of the nozzle guard  32 . The maintenance unit  30  is arranged inside the left end portion of the casing  21 . As illustrated in  FIG. 7 , the maintenance unit  30  is equipped with four wipers  81 , four wiper fixing sections  82 , a wiper driving unit  83 , and four cleansing tanks  84 . 
     Each of the wipers  81  is a member that wipes the ink ejection surface  36   a  of the ink jet head  31  and the lower surface of the nozzle guard  32 . The wipers  81  are made of a material such as elastically deformable rubber, and are formed in the shape of a plate. The sides of each of the wipers  81  toward the leading ends thereof may be divided into a central portion  81   a , a left portion  81   b , and a right portion  81   c . The central portion  81   a  is a portion which is inserted into the opening  46  of the nozzle guard  32  and wipes the ink ejection surface  36   a  of the ink jet head  31 . The leading end of the central portion  81   a  protrudes from the distal ends of the left side portion  81   b  and the right side portion  81   c . The width (the length in the left-right direction) of the central portion  81   a  is slightly smaller than the width of the opening  46  of the nozzle guard  32 . The left side portion  81   b  and the right side portion  81   c  are portions for wiping the lower surface of the nozzle guard  32 . 
     The wiper fixing sections  82  fix the wipers  81  to wiper driving belts  86  to be described later. 
     The wiper driving unit  83  moves the wipers  81  in the arrangement direction of the ink ejecting ports  37  of the nozzles of the ink jet head  31 . The wiper driving unit  83  is equipped with four wiper drive belts  86 , a drive roller  87 , and driven rollers  88 ,  89 . 
     Each of the wiper drive belt  86  is an annular belt wrapped around the drive roller  87  and the driven rollers  88 ,  89 . One of the wipers  81  is attached to each wiper drive belt  86  via one of the wiper fixing portions  82 . The wiper drive belt  86  moves the wiper  81  by rotating in the direction indicated by the arrow illustrated in  FIG. 7  (the counterclockwise direction as viewed from the left side). Thereby, the wipers  81  wipe the ink ejection surface  36   a  and the lower surface of the nozzle guard  32 , while moving from the front side to the rear side in a horizontal section of the wiper driving belts  86  which are stretched between the driving roller  87  and the driven roller  88 . 
     The driving roller  87  is rotationally driven by a motor (not shown), thereby rotating the wiper driving belt  86 . The driven rollers  88 ,  89  support the four wiper drive belts  86  together with the drive roller  87 . The driven rollers  88 ,  89  are driven to rotate by the drive roller  87  via the wiper drive belts  86 . The driven roller  88  is arranged at the same height as the driving roller  87  and behind the driving roller  87 . The driven roller  89  is disposed below an intermediate position between the driving roller  87  and the driven roller  88  in the front-back direction. 
     The cleansing tanks  84  store cleansing liquid. The cleansing tanks  84  are disposed below the wiper driving belt  86 . Thereby, when the wipers  81  pass through the vicinity of the driven roller  89  due to the rotation of the wiper driving belts  86 , the wipers  81  are immersed in the cleaning liquid in the cleansing tanks  84 , and the cleansing liquid adheres to the wiper  81 . 
     The cleaning liquid is a liquid that dissolves adhered substances (including ink components and flakes and powder on the surface of the print medium) adhered to the ink ejection surface  36   a  and the surface of the nozzle guard  32 . It is preferable for an aqueous solvent containing water and a surfactant to be employed as the cleansing liquid. Examples of the surfactant include anionic surfactants such as sodium fatty acid, sodium alkylbenzenesulfonate, sodium alkylsulfonate, sodium α-olefin sulfonate, sodium alkylsulfate, sodium alkyl ether sulfate, sodium α-sulfo fatty acid ester, sodium alkylphosphate ester; cationic surfactants such as alkyltrimethylammonium and dialkyldimethylammonium; nonionic surfactants such as sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, sucrose fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and amphoteric surfactants such as alkyl amino fatty acid sodium, alkyl betaine, and alkylamine oxide. Further, polymeric surfactants, silicone surfactants, fluorine surfactants, acetylene glycol surfactants, etc. may be employed. Among these, it is preferable for polyoxyethylene alkyl ether to be employed, and it is more preferable for the HLB value thereof to be 11 to 17, the number of carbon atoms of the alkyl group to be within a range from 8 to 15, and the number of moles of ethylene oxide added to be within a range from 6 to 25. 
     Further, it is preferable for the cleansing liquid to further contain a thickener. A water soluble polymeric thickener or a clay mineral based thickener may be employed as the thickener. Natural polymers, semisynthetic polymers, synthetic polymers may be employed as the water soluble polymeric thickener. Examples of natural polymers include natural plant polymers such as gum arabic, carrageenan, guar gum, locust bean gum, pectin, tragacanth gum, cornstarch, konjak mannan, agar; natural microbial polymers such as pullulan, xanthan gum and dextrin; and natural animal polymers such as gelatin, casein, glue. Examples of semisynthetic polymers include cellulose semisynthetic polymers such as ethylcellulose, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, methylcellulose, and hydroxypropylmethylcellulose; starch series polymers such as hydroxyethylstarch, carboxymethylstarch sodium, and cyclodextrin; alginic acid based semisynthetic polymers such as sodium alginate and propylene glycol alginate; and sodium hyaluronate. Examples of synthetic polymers include vinyl synthetic polymers such as polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl methyl ether, poly N-vinyl acetamide, and polyacrylamide; polyethylene oxide, polyethylene imine, and polyurethane. Examples of the clay mineral based thickener include smectite clay minerals such as montmorillonite, hectorite, and saponite. Among these, it is preferable for hydroxypropyl methyl cellulose to be employed. 
     In addition to the above components, the cleansing liquid may optionally contain a water soluble organic solvent, a pH adjusting agent, an antioxidant, a preservative, etc., as appropriate. It is preferable for the viscosity of the cleansing liquid is preferably within a range from 5 to 200 mPa·s at 23° C., and more preferably a range from 10 to 100 mPa·s. 
     As illustrated in  FIG. 2 , one end of an ink supply pipe  53  is connected to each of the ink jet heads  31 . As illustrated in  FIG. 8 , an ink tank  51  that stores ink is connected to the other end of the ink supply pipe  53 . A supply pump  52  is provided in the ink supply pipe  53 . By operating the supply pump  52 , the ink which is stored in the ink tank  51  is supplied to the ink jet head  31   s  via the ink supply pipe  53 . 
     In the present embodiment, in a state in which the absorbing member  50  is pressed onto the opening  46  of the nozzle guard  32  of the ink jet head  31  as illustrated in  FIG. 8 , ink is supplied to the ink jet head  31  by the supply pump  52 , and purging is performed. At this time, the purging operation and the ink removing operation by the absorbing member  50  are performed in parallel by suction being conducted by the suction pump  69 . The purging operation and ink removing operation will be described in detail later. 
       FIG. 9  is a block diagram showing a control system of the ink jet printing apparatus  1  of the present embodiment. The ink jet printing apparatus  1  is equipped with a control unit  5  that controls the entire apparatus. The control unit  5  is equipped with a CPU (Central Processing Unit), a semiconductor memory, a hard disk, etc. The control unit  5  executes a program which is stored in advance in a storage medium such as a semiconductor memory or a hard disk, and operates an electric circuit to control each of the components illustrated in  FIG. 9 . 
     Next, a printing operation of the ink jet printing apparatus  1  of the present embodiment will be described. 
     When the ink jet printing apparatus  1  is in a standby state before a printing operation is initiated, the shuttle unit  4  is disposed at a standby position. The standby position of the shuttle unit  4  is the position of the shuttle unit  4  indicated by the solid line in  FIG. 1  and is at the back end of the gantry section  11  of the shuttle base unit  2 . 
     When a print job is input, the control unit  5  controls the sub scanning drive motor  12  to move the shuttle unit  4  from the standby position to a print processing start position. The printing process starting position of the shuttle unit  4  is the position of the shuttle unit  4  indicated by the two dot chain line in  FIG. 1 , and is at the front end portion of the gantry section  11  of the shuttle base unit  2 . A print medium  15  is installed on the medium placement surface  3   a  of the flat bed unit  3  prior to the print job being input. 
     Next, while controlling the main scanning drive motor  23  to move the head unit  26  in the main scanning direction, the control unit  5  controls the ink jet heads  31  based on the inputted print job to control the ink ejecting ports  37  such that printing for one pass is performed. Next, the control unit  5  controls the sub scanning drive motor  12  to move the shuttle unit  4  backward to the printing position for a next pass. The control unit  5  forms an image on the print medium  15  by alternately repeating the printing for one pass and the movement of the shuttle unit  4 . 
     When printing of one sheet is completed, the control section  5  controls the sub scanning drive motor  12  to return the shuttle unit  4  to the standby position. Then, the printing operation is completed. 
     Next, a maintenance operation which is performed by the ink jet printing apparatus  1  of the present embodiment will be described with reference to  FIGS. 10 and 11 . The maintenance operation of the present embodiment is an operation for removing ink which has entered the gap  40  between the nozzle guard  32  and the ink ejection surface  36   a  and for forming a meniscus at the ink ejecting port  37  of each of the nozzles. 
     The maintenance operation is performed when the shuttle unit  4  is placed at the standby position. At this time, the head unit  26  in the shuttle unit  4  is disposed at the standby position shown in  FIG. 2 . Then, the capping unit  66  is in a state in which it is abutting each of the ink jet heads  31  of the head unit  26 , which is arranged at the standby position as illustrated in  FIG. 10A , that is, the opening  46  of the nozzle guard  32  of each of the ink jet heads  31  is hermetically sealed by one of the caps  71  of the capping unit  66 . 
     When the maintenance operation is initiated, first, the cap elevating motor  67  is controlled by the control unit  5  such that the capping unit  66  is lowered and is disposed at the retracted position. Then, the absorbing member setting mechanism  29  is controlled by the control unit  5 , and the absorbing member  50  is disposed on the caps  71  of the capping unit  66 , as illustrated in  FIG. 10B . 
     Next, the cap elevating motor  67  is controlled by the control unit  5  to raise the capping unit  66 , and the absorbing member  50  is brought into a state in which it is being pressed onto the opening  46  of the ink jet head  31 , as illustrated in  FIG. 10C . 
     Thereafter, the supply pump  52  is controlled by the control unit  5 , and as indicated by the arrows illustrated in  FIG. 11A , ink is supplied to each ink jet head  31  and pressurized to perform the purging operation. In parallel with this purging operation, the suction pump  69  is controlled by the control unit  5 , and suction is conducted by the suction pump  69 . By conducting the purging and the suction in parallel as described above, the ink which has entered the gap  40  between the nozzle guard  32  and the ink ejection surface  36   a  is absorbed and removed by the absorbing member  50 . In parallel with the removal of the ink in the gap  40 , a meniscus is formed at the ink ejecting port  37  of each nozzle of the ink jet head  31 . 
     At this time, the control unit  5  sets the pressurizing conditions of the supply pump  52  and the suction conditions of the suction pump  69  to those that enable the ink within the gap  40  to be removed and the meniscus which is formed at the ink ejecting port  37  of each nozzle to be maintained. Specifically, the rotational speed of the supply pump  52  is set to 100 rpm and the supply pump is driven for 10 seconds as the pressurizing conditions of the supply pump  52 , for example. In addition, the rotational speed of the suction pump  69  is set to be within a range from 90 rpm to 150 rpm, and the suction pump  69  is driven for 30 seconds. WPX1-P3.2FA4-W6-CP by Welco are employed as the supply pump  52  and the suction pump  69 , respectively. 
     After a 10 second purging operation by pressurization by the supply pump  52  and suctioning by the suction pump  69  is complete, the suction by the suction pump  69  is continued for 20 seconds (30 seconds minus 10 seconds), as described above (refer to  FIG. 11B ). Thereby, the ink absorbed by the absorbing member  50  is suctioned toward the side of the capping unit  66 , flows to the suction apertures  78  which are formed in the bottom portions  76  of the cap  71 , and is stored in the waste liquid tank  70  via the suction pipe  68 . By continuing suctioning by the suction pump  69  after the purging operation is completed in this manner, the ink which is absorbed by the absorbing member  50  can be recovered. As a result, the absorbing member  50  can be reused. 
     After suction is conducted by the suction pump  69  for a predetermined amount of time, the suction pump  69  is stopped, as illustrated in  FIG. 11C . 
     The above is the explanation of the maintenance operation of the present embodiment. 
     Note that in the case that a printing process is performed after the maintenance operation, the capping unit  66  descends, the absorbing member  50  is removed from the cap  71  and is moved to the retracted position, the head unit  26  is raised by the head elevating motor  25  to move to a predetermined position, and then moves in the left-right direction along the main scanning drive guide  22  to perform the printing process. 
     In the maintenance operation of the present embodiment, it is not necessary to provide a separate mechanism for pressing the absorbing member  50 , because the absorbing member  50  is pressed onto the opening  46  of the nozzle guard  32  employing the capping unit  66 . Accordingly, miniaturization of the apparatus can be achieved. 
     In addition, it is not necessary to secure time for the ink removing operation separate from the purging operation because the ink removing operation to remove ink from the gap  40  between the nozzle guard  32  and the ink ejection surface  36   a  and the purging operation are conducted in parallel. Accordingly, printing processes can be initiated immediately. 
     Further, even in the case that the ink jet heads  31  are moved, it is possible to suppress ejection failure caused by the movement of the ink jet heads  31 . 
     Note that in the case that a printing process is not performed following the maintenance operation, the capping unit  66  descends, the absorbing member  50  is removed from the cap  71  and is moved to the retracted position, and then the capping unit  66  is raised again to be in a state in which the capping unit  66  abuts the ink jet heads  31 , as illustrated in  FIG. 10A . 
     The maintenance operation may be performed automatically immediately prior to initiating a printing process, or may be performed according to a command which is input by a user. As a further alternative, the maintenance operation may be performed at every preset period or each time after a preset number of sheets is printed. 
     In the present embodiment, when the maintenance operation is performed, the capping unit  66  is moved toward the ink jet head  31  such that the absorbing member  50  is pressed onto the opening  46  of the ink jet heads  31 . However, the present invention is not limited to this configuration. The ink jet heads  31  may be moved toward the side of the capping unit  66  such that the absorbing member  50  is pressed onto the opening  46  of the ink jet heads  31 . Alternatively, the absorbing member  50  may be pressed onto the opening  46  of the ink jet heads  31  by moving both the ink jet heads  31  and the capping unit  66  towards each other. 
     Next, a wipe cleaning operation in the ink jet printing apparatus  1  of the present embodiment will be described. The wipe cleaning operation of the present embodiment is an operation that removes ink, dust, etc. which are adhered to the ink ejection surface  36   a  and the lower surface of the nozzle guard  32 . 
     When performing out the wipe cleaning operation, first, the control unit  5  controls the wiper driving unit  83  to causes the wipers  81  to move and pass through the cleansing tank  84 , thereby cleaning the wiper  81  and causing the cleaning liquid to adhere to the wipers  81 . 
     Next, after releasing the capping of the opening  46  of the nozzle guard  32  by the capping unit  66 , the control unit  5  controls the main scanning drive motor  23  to move the head units  26  from a home position to a position above the maintenance unit  30 . Thereafter, the control unit  5  controls the head elevating motor  25  to lower the head unit  26  to a cleaning position. The cleaning position of the head unit  26  is the position at which the wipers  81  wipe the ink ejection surface  36   a  of the head units  26 . 
     When the movement of the head unit  26  to the cleaning position is completed, the wipers  81  are arranged at the front side of the front end of the nozzle guard  32 . Further, the leading ends (upper end) of the central portions  81   a  of the wipers  81  are higher than the ink ejection surface  36   a , and the left side portions  81   b  and the right side portions  81   c  of the wipers  81  are higher than the lower surface of the nozzle guard  32 . 
     Next, the control unit  5  causes the wiper driving unit  83  to initiate movement of the wipers  81 . When the wipers  81  move backward and come into contact with the nozzle guard  32 , the wipers  81  are pressed by the nozzle guard  32  and are elastically deformed. Then, along with the backward movement, the upper end portions of the center portions  81   a , the left side portions  81   b , and the right side portions  81   c  of the wipers  81  slide along the lower surface of the nozzle guard  32  and perform wiping. Thereby, ink and dirt which are adhered to the lower surface of the nozzle guard  32  are wiped off by the wipers  81 . 
     When the wipers  81  reach the front end of the opening  46  of the nozzle guard  32 , the central portions  81   a  of the wipers  81  are inserted into the opening  46 . Thereafter, the leading end portions of the central portions  81   a  of the wipers  81  wipe the ink ejection surface  36   a . Thereby, ink and dirt which are adhered to the ink ejection surface  36   a  are wiped off. 
     When the wipers  81  reach the rear end of the opening  46  of the nozzle guard  32 , the central portions  81   a  of the wipers  81  exit the opening  46 . Thereafter, the upper end portions of the central portions  81   a , the left side portions  81   b , and the right side portions  81   c  of the wipers  81  wipe the lower surface of the nozzle guard  32 . When the wipers  81  reach the back side of the nozzle guard  32  from the back end thereof, the control unit  5  terminates the movement of the wiper  81 . Thereby, the wipe cleaning operation is completed. 
     When the wipe cleaning operation is completed, the control unit  5  returns the head unit  26  from the cleaning position to the home position, and caps the opening  46  of the nozzle guard  32  with the capping unit  66 . 
     Note that the wipe cleaning operation may be performed automatically immediately before initiating a printing process or may be performed according to a command which is input by a user. As a further alternative, the wipe cleaning operation may be performed every preset period or each time after a preset number of sheets is printed. 
     In addition, the ink jet printing apparatus  1  of the embodiment described above, the absorbing member  50  is disposed on the cap  71  of the capping unit  66 . Alternatively, a sheet shaped elastic member  54  may be provided between the caps  71  of the capping unit  66  and the absorbing member  50 , and the maintenance operation described above may be performed. When performing the maintenance operation, the elastic member  54  may be set on the caps  71  of the capping unit  66  by employing a predetermined setting mechanism (not shown). 
     A sponge cloth, a silicon sheet, a rubber sheet, etc. may be employed as the elastic member  54 , for example. Note that in the case that a member that does not allow air to pass therethrough such as a silicon sheet, a rubber sheet or the like is employed as the elastic member  54 , the aforementioned suction operation can be appropriately performed if a plurality of penetrating apertures are formed in the elastic member  54 . 
     By providing the elastic member  54  between the cap  71  and the absorbing member  50 , when the absorbing member  50  is pressed onto the opening  46  of the nozzle guard  32  of the ink jet head  31 , close contact properties between the absorbing member  50  and the nozzle guard  32  can be improved. As a result, it will become possible to uniformly remove ink that seeps out from the gap  40  between the ink ejection surface  36   a  and the nozzle guard  32 . 
     In the ink jet printing apparatus  1  of the embodiment described above, the absorbing member  50  is pressed onto the opening  46  of the nozzle guard  32  by employing the capping unit  66 . Alternatively, it is also possible to provide a pressing mechanism within the shuttle unit  4  separate from the capping unit  66 , and the absorbing member  50  may be pressed onto the opening  46  of the nozzle guard  32  employing the pressing mechanism. 
       FIG. 13  is a diagram that illustrates an example of a pressing member  90  separate from the capping unit  66 . The pressing member  90  is provided with the absorbing member  50  in the same manner as the caps  71  of the capping unit  66 . During the maintenance operation, the pressing member  90  is moved to the side of the ink jet head  31  by a predetermined elevating mechanism (not shown), and the absorbing member  50  is pressed onto the opening  46  of the nozzle guard  32 . 
       FIG. 14  is a cross sectional view of the pressing member  90  taken along the line B-B of  FIG. 13 . As illustrated in  FIGS. 13 and 14 , the pressing member  90  is equipped with a base  91 , an installation base  92 , and a plurality of spring members  93 . The base  91  is a member made of a rectangular parallelepiped resin, in which a rectangular parallelepiped shaped recess  91   a  is formed. The installation base  92  is a member made of rectangular parallelepiped resin, and is installed in the recess  91   a  of the base  91 . 
     The spring members  93  are installed together with the installation base  92  in the recess  91   a  of the base  91 . One of the ends of the spring members  93  are connected to a bottom surface  91   b  of the recess  91   a , and the other of the ends are connected to the lower surface of the installation base  92 . The spring members  93  urge the installation base  92  upward. The installation base  92  moves in the direction of the arrow (up-down direction) illustrated in  FIG. 14  by elastic force imparted by the spring member  93 . Although only two spring members  93  are illustrated in  FIG. 14 , it is preferable for the spring members  93  to be provided at the four corners on the lower surface of the installation base  92  or in a uniformly distributed manner with respect to the lower surface of the installation base  92 . 
     As illustrated in  FIG. 14 , when the absorbing member  50  is installed on the installation base  92 , the pressing member  90  moves toward the side of the ink jet heads  31  and is pressed onto the nozzle guard  32  of the ink jet head  31 , the spring members  93  cause the upper surface of the installation base  92  to move flexibly. Thereby, the close contact properties between the absorbing member  50  and the nozzle guard  32  can be improved, and ink that seeps out from the gap  40  between the ink ejection surface  36   a  and the nozzle guard  32  can be uniformly removed. 
     Suction apertures  94  which are connected to the suction pipes  68  are formed in the pressing member  90  in the same manner as in the capping unit  66 . 
     Further, the pressing member  90  illustrated in  FIGS. 13 and 14  employs the spring members  93 . Alternatively, other elastic members such as rubber members may be employed. 
     Further, as illustrated in  FIG. 12 , a sheet shaped elastic member such as a sponge cloth may be provided between the installation base  92  of the pressing member  90  and the absorbing member  50 . 
     In the case that the absorbing member  50  is pressed onto the nozzle guard  32  by the capping unit  66 , a spring member may be provided such that the caps  71  can move in the up-down direction in the same manner as the pressing member  90  described above. 
     Further, it is preferable for the absorbing member  50  to contain a liquid having solubility with respect to dried ink. By the absorbing member  50  containing such a liquid, it will become possible to appropriately remove ink which has seeped out from the gap  40  between the ink ejection surface  36   a  and the nozzle guard  32  and has dried. It is preferable for a liquid which is the same as the cleansing liquid described above to be employed as the liquid having solubility with respect to dried ink. Further, an absorbing member  50  that contains the liquid in advance may be employed, or a tank for storing the liquid may be provided, and a mechanical mechanism that immerses the absorbing member  50  in the tank, and then arranges the absorbing member  50  on the caps  71  of the capping unit  66  or the installation base  92  of the pressing member  90  may be provided in the shuttle unit  4   
     In addition, in the above embodiment, purging is performed in a state in which the absorbing member  50  is pressed against the opening  46  of the inkjet head  31 . At the same time, suctioning by the suction pump  69  causes the ink which has entered the gaps between the nozzle guard  32  and the ink ejecting surfaces  36   a  to be absorbed by the absorbing member  50  and forms a meniscus at the ink ejection port  37  of each of the nozzles. However, the method by which the maintenance operation is performed is not limited to this, and other methods may be applied. Hereinafter, another embodiment of the maintenance operation will be described with reference to  FIG. 15  and  FIG. 16 . 
     First, in the previously described embodiment, the absorbing member  50  is pressed against the ink jet head  31  by the capping unit  66 . However, in the other embodiment, a pressing base  100  is provided in the shuttle unit  4  in addition to the capping unit  66 . 
     Then, by moving the pressing base  100  on which the absorbing member  50  is mounted toward the ink jet head  31 , the absorbing member  50  is pressed against the ink jet head  31  at a predetermined pressure. The pressing base  100  is provided for each ink jet head  31 , and is formed of a material such as resin having a certain degree of rigidity that does not deform by, for example, a pressing operation. However, an elastic sheet made of a sponge cloth, a silicone sheet or a rubber sheet may be provided on the pressing base  100  and the absorbing member  50  may be provided on the elastic sheet, in order to improve the close contact properties of the absorbing member  50  with respect to the nozzle guard  32 . 
     In the maintenance operation of the alternate embodiment, first, the supply pump  52  is controlled by the control unit  5  and purging is performed in a state where the ink jet head  31  is disposed above the capping unit  66 , as illustrated in  FIG. 15A . At the time of this purging operation, the opening  46  of the nozzle guard  32  of the ink jet head  31  may be hermetically sealed by the cap  71  of the capping unit  66 , or the opening  46  may be an open state, as illustrated in  FIG. 15A . In addition, the ink discharged from the ink jet head  31  by this purging operation is received by the capping unit  66 , and suctioned from the capping unit  66  by the suction pump  69  being controlled by the control unit  5  to recover the ink. This purging operation results in a state in which ink droplets D are adhered to the ink discharge ports  37  of the ink jet head  31 , as illustrated in  FIG. 15A . 
     Next, the inkjet head  31  moves and is arranged above the pressing base  100 , as illustrated in  FIG. 15B . Then, the absorbing member setting mechanism is controlled by the control unit  5 , and the absorbing member  50  is set on the pressing base  100 . Note that the absorbing member setting mechanism is for setting the absorbing member  50  on the pressing base  100 , and the specific configuration thereof is the same as that of the absorbing member setting mechanism  29  illustrated in  FIG. 2  and  FIG. 9 . 
     Next, a predetermined drive motor (not shown) is controlled by the control unit  5  to raise the pressing base  100 , resulting in a state in which the absorbing member  50  is pressed against the opening  46  of the inkjet head  31 , as illustrated in  FIG. 15C . 
     Then, after the absorbing member  50  is pressed against the opening  46  of the ink jet head  31  at a predetermined pressure for a predetermined amount of time, the driving motor is controlled by the control unit  5 , causing the pressing base  100  to descend and move to a standby position, as illustrated in  FIG. 16D . 
     Thereafter, the inkjet head  31  moves and is placed on the capping unit  66  as illustrated in  FIG. 16E . Then, the capping unit  66  ascends, abuts the inkjet head  31 , and the opening  46  of the nozzle guard  32  of the inkjet head  31  is sealed. The above is a description of the alternate embodiment of the maintenance operation. 
     Here, similarly to the maintenance operation of the previously described embodiment, the maintenance operation of the alternate embodiment described above is an operation that removes the ink that has entered the gap  40  between the nozzle guard  32  and the ink ejection surface  36   a , and forms a meniscus at the ink ejection port  37  of each of the nozzles. 
     In the maintenance operation according to the alternate embodiment, it is preferable for the absorbency and the surface roughness of the absorbing member  50  as well as the pressing pressure and the amount of time that the absorbing member  50  is pressed against the ink jet head  31  by the pressing base  100  to be set appropriately, in order to favorably remove the ink in the gap  40  and to maintain the meniscus formed at each of the nozzles. 
     Specifically, in the case that the absorbency of the absorbing member  50  is low, it is not possible to appropriately remove the ink in the gap  40  of the nozzle guard  32 . Further, in the case that the fibers on the surface of the absorbing member  50  are fluffed, there may be cases in which the fibers enter the ink discharge ports  37  and break the meniscuses therein. 
     In addition, the greater the pressing pressure, the ink within the gap  40  of the nozzle guard  32  can be pressed outward to the exterior of the gap  40  and can be easily absorbed by the absorbing member  50 . However, if the pressing pressure is excessively large, there may be cases in which the absorbing member  50  is pressed excessively strongly against the ink ejection ports  37  and the meniscuses therein are broken, resulting in ink ejection failure. In addition, there may be cases in which the ink that seeps out from the gap  40  of the nozzle guard  32  due to the pressing of the absorbing member  50  reaches the ink ejection port  37  before being absorbed by the absorbing member  32 , blocking the ink ejection port  37 , resulting in ink ejection failure.  FIG. 17  is a diagram that illustrates an example of the state of the ink that seeps out from the gap  40  of the nozzle guard  32  by the pressing the absorbing member  50 . 
     In addition, in the case that the pressing time is excessively short, it is not possible to sufficiently absorb the ink that seeps out from the gap  40 . In the case that the pressing time is excessively long, there may be cases in which the meniscuses which are formed in the ink discharge ports  37  will be broken. 
     Taking these factors into consideration, it is preferable for an absorbing member having an absorbency of 10 mm/5 min or greater and 80 mm/5 min or less and a surface roughness Rz of 410 μm or less to be employed as the absorbing member  50 . It is also preferable for the absorbing member  50  to be pressed against the ink jet head  31  with a pressing pressure of 10 kPa or greater and 80 kPa or less for an amount of time 7 seconds or greater and 60 seconds or less. By adopting such a configuration, it is possible to favorably remove the ink in the gap  40  of the nozzle guard  32  and appropriately maintain the meniscus which is formed in each of the nozzles. 
     Note that the bases for setting the absorbency and the surface roughness Rz of the absorbing member  50  as well as the numerical values of the pressing pressure and the pressing time of the absorbing member  50  will be shown by Examples and Comparative Examples, which will be described later. 
     In addition, it is preferable for the absorbing member  50  to be formed by fibers which are thicker than the diameter of the nozzles, in order to prevent the fibers of the absorbing member  50  from breaking the meniscuses which are formed in the ink discharge ports  37  as described above, By adopting such a configuration, it will become possible to prevent the meniscuses from being broken due to the fibers of the absorbing member  50  entering the ink ejection ports  37 . 
     The thicknesses of the fibers of the absorbing member  50  are measured by observing the upper surface of the absorbing member  50  with an optical microscope “AZ-100M” by NIKON, and measuring the distance between two points with a measuring tool. Specifically, fibers that protrude from the upper surface of the compressed and flattened absorbent member  50  are designated as targets of measurement, two points that yield the largest diameter are specified, and the distance therebetween is measured. Then, the average value of the measurement results of ten fibers is designated as the thickness of the fibers of the absorbing member  50  as referred to here. 
     In addition, it is preferable for the lengths of the fiber on the surface of the absorbing member  50  to be shorter than the distance from the ink ejection surface  36   a  of the nozzles to the surface  32  of the nozzle guard (the surface that faces the ink ejection surface  36   a ; refer to  FIG. 4 ). By adopting such a configuration, it will become possible to prevent the fibers of the absorbing member  50  from entering the ink discharge port  37 , and it will become possible to prevent the meniscuses which are formed at the ink discharge ports  37  from being broken. 
     The lengths of the fiber on the surface of the absorbing member  50  are measured by observing the side end face of the absorbing member  50  with an optical microscope “AZ-100M” by NIKON, and measuring the distance between two points with a measuring tool. Specifically, fibers that protrude from the upper surface of the compressed and flattened absorbent member  50  are designated as targets of measurement, the two ends of protruding portions of the fibers are specified, and the distance therebetween is measured. The average value of the measurement results of ten fibers is designated as the length of the fibers on the surface of the absorbing member  50  as referred to here. 
     Further, it is preferable for the intervals of the fibers on the surface of the absorbing member  50  to be wider than the arrangement pitch of the nozzles (the intervals among adjacent nozzles). By adopting such a configuration, it will become possible to prevent the fibers of the absorbing member  50  from entering the ink ejection ports  37 , and it will become possible to suppress breakage of the meniscuses which are formed in each of the ink ejection ports  37 . 
     The intervals among the fibers on the surface of the absorbing member  50  are measured by observing the upper surface of the absorbing member  50  with an optical microscope “AZ-100M” manufactured by NIKON, and by measuring the distance between two points with a measuring tool. Specifically, compressed and flattened fibers that protrude from the upper surface of the absorbent member  50  are designated as targets of measurement. The distances between pairs of adjacent fibers are measured. Then, the average value of the measurement results of ten pairs of fibers is designated as the intervals among the fibers on the surface of the absorbing member  50  referred to here. 
     Example 1 
     The absorbency and surface roughness Rz of the absorbent member  50  as well as the pressing pressure and pressing time of the absorbent member  50  described above will be described below with reference to Examples and Comparative Examples. 
     First, a method for measuring the absorbency, the surface roughness Rz, the pressing pressure and the pressing time of the absorbing member  50  will be described. 
     With respect to the water absorbency, the target of measurement was not water but ink. The absorbency with respect to ink was measured by a method in accordance with the water absorption test based on the Birec method of JIS L 1907. Test pieces were 1 cm wide×20 cm long, the initial immersion length was 3 cm, and the immersion time was 5 min. 
     The surface roughness Rz, is a measured value of the maximum height roughness of ISO 25178 surface properties (measurement of surface roughness). A color 3D laser microscope “VK-8700” by KEYENCE was employed as a measuring instrument. 
     The pressing pressure was measured by fixing a push pull gauge (FGX-50R by Nidec Shimpo) at the same height as the mounting position of the inkjet head, placing the absorbing member on the pressing base, and pressing the absorbing member against the inkjet head. The amount of time for which the absorbing member is pressed against the ink jet head was designated as an amount of time from a point in time when the pressing pressure reached the values shown in Table 1 through Table 4 below to a point in time when the pressing was ceased. 
     Next, the evaluation method for each of the conditions will be described. Regarding evaluations, whether ink in the gap  40  of the nozzle guard  32  was removed (removal of gap ink), and whether ink was normally ejected from each nozzle (nozzle check) were evaluated. 
     First, prior to conducting the evaluations, purging was performed after the ink jet printing apparatus was used for a certain period of time. Next, the wipe cleaning operation described above was performed, and a nozzle check pattern which was set in advance was printed on a printing medium  15 . Then, by visually checking the printing results, it was confirmed that ink was normally ejected from all of the nozzles. 
     Next, as an evaluation procedure, after purging, various absorption members  50  shown in Table 1 through Table 4 below were placed on the pressing base  100 , and the pressing operation illustrated in  FIG. 15C  was performed at the pressing pressures and the amounts of pressing time shown in Table 1 through Table 4 below 
     With respect to the removal of gap ink, the bottom surface  41  of the nozzle guard  32  (refer to  FIG. 3  and  FIG. 4 ) was pressed with a cotton swab after the pressing operation, and evaluations were conducted by visually checking whether ink seeps out from the gap  40 . In Table 1 through Table 4, cases in which no ink seepage was observed were evaluated as “A”, cases in which slight seepage of ink was observed were evaluated as “B”, and cases in which there was a certain amount of ink seepage were was evaluated as “NG”. The removal of gap ink is at a level at which there is no particular problem up to “B”. 
     With respect to the nozzle check, a nozzle check pattern was printed after the pressing operation described above, and it was visually confirmed whether there were any nozzles from which ink was not normally ejected (ejection dropout). Note that a nozzle from which ink is not normally ejected is a nozzle in which breakage of a meniscus causes ejection failure. The number of nozzles that exhibit ejection dropout was counted per each single ink jet head  31 . In Table 1 through Table 4 below, cases in which the number of nozzles that exhibited ejection dropout was 0 or greater and 3 or less were evaluated as “A”, cases in which the number of nozzles that exhibited ejection dropout was 4 or greater and 9 or less were evaluated as “B”, and cases in which the number of nozzles that exhibited ejection dropout was 10 or greater were evaluated as “NG”. Note that the number of nozzles in one inkjet head  31  is 508. The ejection dropout is at a level at which there is no particular problem up to “B”. 
     Next, specific Examples and Comparative Examples will be described. Table 1 shows the results of evaluations of ink removal and ejection dropout when the pressing operation described above was performed with Examples 1 to 8 and Comparative Examples 1 to 3 shown in Table 1 that employed various absorbing members  50  having different absorbencies and surface roughnesses Rz at the pressing pressures and amounts of pressing time shown in Table 1. Here, all of the pressing pressures was set to 30 kPa, and all of the amounts of pressing time were set to 10 seconds. 
     From the evaluation results shown in Table 1, it was found that it is preferable for the absorbency of the absorbing member  50  to be within a range of 10 mm/5 min or greater and 80 mm/5 min or less. In addition, it was found that it is preferable for the surface roughness Rz of the absorbing member  50  to be within a range of 410 μm or less. 
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                   
                 Surface 
                   
                 Pressing 
                 Pressing 
                   
                   
               
               
                   
                   
                   
                 Roughness Rz 
                 Absorbency 
                 Pressure 
                 Time 
                 Gap Ink 
                 Nozzle 
               
               
                   
                 Absorbing Member 
                 Material 
                 (μm) 
                 (mm/5 min) 
                 (kPa) 
                 (seconds) 
                 Removal 
                 Check 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Example 1 
                 ASPURE Wiper (TM) 
                 Polyester 
                 322.99 
                 70 
                 30 
                 10 
                 A 
                 A 
               
               
                 Example 2 
                 Sponge Cloth 
                 Cellulose 70% 
                 322.31 
                 80 
                 30 
                 10 
                 A 
                 A 
               
               
                   
                   
                 Cotton 30% 
               
               
                 Example 3 
                 Printing Paper Arabel (TM) 
                 Cellulose 
                 119.52 
                 10 
                 30 
                 10 
                 A 
                 B 
               
               
                 Example 4 
                 Water Color Paper 
                 Cellulose 
                 173.43 
                 20 
                 30 
                 10 
                 A 
                 A 
               
               
                 Example 5 
                 Sofras (TM) 
                 Polyurethane 
                 140.63 
                 70 
                 30 
                 10 
                 A 
                 A 
               
               
                 Example 6 
                 Acoustic Mute Board (AMB) 
                 Polyester 
                 340.6 
                 80 
                 30 
                 10 
                 A 
                 A 
               
               
                 Example 7 
                 Cloth 
                 Rayon 80% 
                 322.73 
                 70 
                 30 
                 10 
                 A 
                 A 
               
               
                   
                   
                 Polyester 20% 
               
               
                 Example 8 
                 Felt 1 
                 Wool 60% 
                 358.88 
                 70 
                 30 
                 10 
                 A 
                 A 
               
               
                   
                   
                 Rayon 40% 
               
               
                 Comparative 
                 Felt 2 
                 Wool 60% 
                 414.78 
                 70 
                 30 
                 10 
                 A 
                 NG 
               
               
                 Example 1 
                   
                 Rayon 40% 
               
               
                 Comparative 
                 Printing Paper Van Nouveau (TM) 
                 Cellulose 
                 169.21 
                 5 
                 30 
                 10 
                 NG 
                 NG 
               
               
                 Example 2 
               
               
                 Comparative 
                 Office Paper PW 
                 Cellulose 
                 189.87 
                 5 
                 30 
                 10 
                 NG 
                 NG 
               
               
                 Example 3 
               
               
                   
               
            
           
         
       
     
     Next, Table 2 shows the results of evaluation by changing the pressing pressure employing the absorbing member  50  (printing paper Arabel (registered trademark)) of Example 3, which has an absorbency at the lower limit value. All of the amounts of pressing time were set to 10 seconds. 
     From the evaluation results shown in Table 2, it was found that it is preferable for the pressing pressure to be 10 kPa or greater and 80 kPa or less. Note that it is considered that the pressing pressure was excessively low for Comparative Example 4, and therefore removal of gap ink was evaluated as “NG”. It is also considered that the pressing pressure was excessively high for Comparative Example 5, and therefore meniscuses were broken and nozzle check was evaluated as “NG”. 
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                   
                   
                 Surface 
                   
                 Pressing 
                   
                   
                   
               
               
                   
                   
                   
                 Roughness Rz 
                 Absorbency 
                 Pressure 
                 Pressing Time 
                 Gap Ink 
                 Nozzle 
               
               
                   
                 Absorbing Member 
                 Material 
                 (μm) 
                 (mm/5 min) 
                 (kPa) 
                 (seconds) 
                 Removal 
                 Check 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Example 9 
                 Printing Paper Arabel (TM) 
                 Cellulose 
                 119.52 
                 10 
                 10 
                 10 
                 B 
                 A 
               
               
                 Example 10 
                 Printing Paper Arabel (TM) 
                 Cellulose 
                 119.52 
                 10 
                 15 
                 10 
                 A 
                 A 
               
               
                 Example 11 
                 Printing Paper Arabel (TM) 
                 Cellulose 
                 119.52 
                 10 
                 30 
                 10 
                 A 
                 A 
               
               
                 Example 12 
                 Printing Paper Arabel (TM) 
                 Cellnlose 
                 119.52 
                 10 
                 50 
                 10 
                 A 
                 A 
               
               
                 Example 13 
                 Printing Paper Arabel (TM) 
                 Cellulose 
                 119.52 
                 10 
                 80 
                 10 
                 A 
                 A 
               
               
                 Comparative 
                 Printing Paper Arabel (TM) 
                 Cellulose 
                 119.52 
                 10 
                 5 
                 10 
                 NG 
                 A 
               
               
                 Example 4 
               
               
                 Comparative 
                 Printing Paper Arabel (TM) 
                 Cellulose 
                 119.52 
                 10 
                 100 
                 10 
                 A 
                 NG 
               
               
                 Example 5 
               
               
                   
               
            
           
         
       
     
     Next, Table 3 shows the results of evaluations that were conducted by changing the pressing time using the absorbing member  50  (acoustic mute board (AMB)) of Example 6, which had an absorbency at the upper limit value. All of the pressing pressures were set to 30 kPa. 
     From the evaluation results shown in Table 3, it was found that it is preferable for the amount of pressing time to be 7 seconds or greater and 60 seconds or less. It is considered that the amount of pressing time was too short for Comparative Example 6, and therefore before the ink seeped out from the gap  40  of the nozzle guard  32  was absorbed by the absorbing member  50 , the ink reached the ink discharge ports  37  of the nozzles, resulting in ejection failures and an evaluation of “NG” for nozzle check. In addition, it is considered that the amount of pressing time was too long for Comparative Example 7, resulting in meniscuses being broken and an evaluation of “NG” for nozzle check. 
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                   
                   
                 Surface 
                   
                 Pressing 
                   
                   
                   
               
               
                   
                   
                   
                 Roughness Rz 
                 Absorbency 
                 Pressure 
                 Pressing Time 
                 Gap Ink 
                 Nozzle 
               
               
                   
                 Absorbing Member 
                 Material 
                 (μm) 
                 (mm/5 min) 
                 (kPa) 
                 (seconds) 
                 Removal 
                 Check 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Example 14 
                 Acoustic Mute Board (AMB) 
                 Polyester 
                 340.6 
                 80 
                 30 
                 7 
                 A 
                 A 
               
               
                 Example 15 
                 Acoustic Mute Board (AMB) 
                 Polyester 
                 340.6 
                 80 
                 30 
                 10 
                 A 
                 A 
               
               
                 Example 16 
                 Acoustic Mute Board (AMB) 
                 Polyester 
                 340.6 
                 80 
                 30 
                 20 
                 A 
                 A 
               
               
                 Example 17 
                 Acoustic Mute Board (AMB) 
                 Polyester 
                 340.6 
                 80 
                 30 
                 30 
                 A 
                 A 
               
               
                 Example 18 
                 Acoustic Mute Board (AMB) 
                 Polyester 
                 340.6 
                 80 
                 30 
                 60 
                 A 
                 A 
               
               
                 Comparative 
                 Acoustic Mute Board (AMB) 
                 Polyester 
                 340.6 
                 80 
                 30 
                 5 
                 A 
                 NG 
               
               
                 Example 6 
               
               
                 Comparative 
                 Acoustic Mute Board (AMB) 
                 Polyester 
                 340.6 
                 80 
                 30 
                 90 
                 A 
                 NG 
               
               
                 Example 7 
               
               
                   
               
            
           
         
       
     
     Next, the results of evaluations that were conducted employing the absorbing member  50  of Example 3 (printing paper Arabel (registered trademark)), which had an absorbency at the lower limit value with pressing pressures of 10 kPa and 80 kPa, and amounts of pressing time of 7 seconds and 60 seconds, based on the evaluation results of Tables 1 through 3, are shown in Table 4 (Example 19 through Example 22). In addition, the results of evaluations that were conducted employing the absorbing member  50  of Example 6 (AMB), which had an absorbency at the upper limit value with pressing pressures of 10 kPa and 80 kPa, and amounts of pressing time of 7 seconds and 60 seconds are also shown in Table 4 (Example 23 through Example 26). 
     From the results in Table 4, it was found that it is preferable for the absorbency of the absorbing member  50  to be 10 mm/5 min or greater and 80 mm/5 min or less, for the pressing pressure to be 10 kPa or greater and 80 kPa or less, and for the amount of pressing time to be 7 seconds or greater and 60 seconds or less. 
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                   
                 TABLE 4 
               
               
                   
                   
               
               
                   
                   
                   
                 Surface 
                   
                 Pressing 
                   
                   
                   
               
               
                   
                   
                   
                 Roughness Rz 
                 Absorbency 
                 Pressure 
                 Pressing Time 
                 Gap Ink 
                 Nozzle 
               
               
                   
                 Absorbing Member 
                 Material 
                 (μm) 
                 (mm/5 min) 
                 (kPa) 
                 (seconds) 
                 Removal 
                 Check 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Example 19 
                 Printing Paper Arabel (TM) 
                 Cellulose 
                 119.52 
                 10 
                 10 
                 7 
                 OK 
                 A 
               
               
                 Example 20 
                 Printing Paper Arabel (TM) 
                 Cellulose 
                 119.52 
                 10 
                 10 
                 60 
                 OK 
                 A 
               
               
                 Example 21 
                 Printing Paper Arabel (TM) 
                 Cellulose 
                 119.52 
                 10 
                 80 
                 7 
                 OK 
                 A 
               
               
                 Example 22 
                 Printing Paper Arabel (TM) 
                 Cellulose 
                 119.52 
                 10 
                 80 
                 60 
                 OK 
                 A 
               
               
                 Example 23 
                 Acoustic Mute Board (AMB) 
                 Polyester 
                 340.6 
                 80 
                 10 
                 7 
                 OK 
                 A 
               
               
                 Example 24 
                 Acoustic Mute Board (AMB) 
                 Polyester 
                 340.6 
                 80 
                 10 
                 60 
                 OK 
                 A 
               
               
                 Example 25 
                 Acoustic Mute Board (AMB) 
                 Polyester 
                 340.6 
                 80 
                 80 
                 7 
                 OK 
                 A 
               
               
                 Example 26 
                 Acoustic Mute Board (AMB) 
                 Polyester 
                 340.6 
                 80 
                 80 
                 60 
                 OK 
                 A 
               
               
                   
               
            
           
         
       
     
     Regarding the ink jet printing apparatus of the present invention, the following additional items will be disclosed. 
     (Additional Items) 
     In the ink jet printing apparatus of the present invention, the pressing mechanism may have a cap member for sealing the opening of the nozzle guard during a standby state in which printing is not performed, and it is possible to press the absorbing member onto the opening of the nozzle guard in a state in which the absorbing member is set in the cap member, by moving at least one of the cap member and the ink jet head. 
     The ink jet printing apparatus of the present invention may have a supply pump for pressurizing and supplying ink to the ink jet head, a suction pump for suctioning ink which is absorbed by the absorbing member, and a control unit for controlling the supply pump and the suction pump, and the control unit may control the supply pump in a state in which the absorbing member is pressed onto the opening of the nozzle guard to eject ink from the ink jet head and may control the suction pump while ejecting the ink to perform suction. 
     In the ink jet printing apparatus of the present invention, a porous sheet having continuous open cells may be used as the absorbing member. 
     In the ink jet printing apparatus of the present invention, it is preferable for the absorbency of the absorbing member to be 10 mm/5 min or greater and 80 mm/5 min or less, for the surface roughness Rz of the absorbing member to be 410 μm or less, and for the pressing mechanism to press the absorbing member against the opening of the nozzle guard with a pressing pressure of 10 kPa or greater and 80 kPa or less for an amount of time 7 seconds or greater and 60 seconds or less. 
     In the ink jet printing apparatus of the present invention, it is preferable for the absorbing member to be formed by fibers which are thicker than the diameter of the nozzles. 
     In the ink jet printing apparatus of the present invention, it is preferable for the lengths of the fibers on the surface of the absorbing member to be shorter than the distance from the ink ejection surface of the nozzles to the surface of the nozzle guard. 
     In the ink jet printing apparatus of the present invention, it is preferable for the intervals among the fibers on the surface of the absorbing member to be wider than the arrangement pitch of the nozzles. 
     In the ink jet printing apparatus of the present invention, the absorbing member may include a liquid having solubility with respect to dried ink. 
     The ink jet printing apparatus of the present invention may be equipped with a conveyance mechanism for conveying the ink jet head in a direction orthogonal to the direction in which the nozzle row extends. 
     EXPLANATION OF THE REFERENCE NUMERALS 
     
         
           1  ink jet printing apparatus 
           2  shuttle base unit 
           3  flatbed unit 
           3   a  medium mounting surface 
           4  shuttle unit 
           5  control unit 
           11  gantry section 
           12  sub scanning drive motor 
           15  printing medium 
           21  casing 
           22  main scanning drive guide 
           23  main scanning drive motor 
           24  head elevating guide 
           25  head elevating motor 
           13 A,  13 B sub scanning drive guides 
           26  head unit 
           28  suction unit 
           29  absorption member setting mechanism 
           30  maintenance unit 
           31  ink jet head 
           32  nozzle guard 
           36  nozzle plate 
           36   a  ink ejection surface 
           37  ink ejecting port 
           40  gap 
           41  bottom plate 
           42  side wall 
           46  opening 
           50  absorbing member 
           51  ink tank 
           52  supply pump 
           53  ink supply pipe 
           54  elastic member 
           66  capping unit 
           67  cap elevating motor 
           68  suction pipe 
           69  suction pump 
           70  waste liquid tank 
           71  cap 
           72  cap base 
           76  bottom portion 
           77  peripheral wall 
           78  suction aperture 
           841  wiper 
           81   a  central portion 
           81   b  left portion 
           81   c  right portion 
           82  wiper fixing section 
           83  wiper driving unit 
           84  cleansing tank 
           86  wiper driving belt 
           87  drive roller 
           88 ,  89  driven rollers 
           90  pressing member 
           91  base 
           91   a  recess 
           91   b  bottom surface 
           92  installation base 
           93  spring member 
           94  suction aperture 
           100  pressing base