Patent Publication Number: US-7901033-B2

Title: Capping device, and recovery device having the same

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present disclosure relates to the subject matter contained in Japanese patent application No. 2007-031589 filed on Feb. 13, 2007, which is expressly incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present invention relates to a capping device suitable for maintaining and/or protecting a fluid ejection device. The present invention also relates to a recovery device including the capping device. 
     BACKGROUND ART 
     An ink jet head of an ink jet printer, which is an example of a fluid ejection device, ejects ink drops in a dot matrix onto a surface of a recording medium, such as plain paper, from a minute nozzle hole, to form, for example, characters or figures. Since the ink jet head has to eject each ink drop at a high speed and precisely towards a target from the nozzle hole, problems, such as clogging, at the nozzle hole undesirably lowers landing precision of the ink drops varies ink ejection amount, resulting in lowered print quality. 
     To eliminate such problems, purging is performed to periodically discharge ink from the nozzle hole, to thereby remove foreign matter, such as air bubbles, solidified ink, or viscosity-increased ink, existing in the nozzle hole. When the printer is not used, the nozzle face is covered with a cap to protect the nozzle hole from drying of the ink in the nozzle hole and adherence of dust to the nozzle hole. 
     In the purging, the nozzle face of the ink jet head, where the nozzle hole is disposed, is covered with a cap, and ink in an ink flow path of the ink jet head and in the nozzle hole is sucked or ejected, to remove any foreign matter in the ink flow path of the ink jet head and in the nozzle hole. In protecting the nozzle hole, the nozzle face, where the nozzle hole is disposed, is covered with the cap to protect the nozzle hole from adherence of, for example, dust; and to prevent drying of the ink by maintaining the humidity in the cap. This way, the ink in the ink nozzle are prevented from being increased in viscosity and being solidified. 
     To increase the volume of ink sucked from the nozzle hole in the purging, the cap is provided with an absorber that absorbs ink. In general, the absorber is accommodated in the cap supported by a cap holder, and is secured by, for example, a holding member. For example, Japanese Unexamined Patent Application Publication No. 2004-142422 (page 19, FIG. 24) discloses a cap including a cap base, an absorber accommodating portion, a function liquid absorber, an absorber holding member, a sealing member, and a seal securing member. The absorber accommodating portion is formed at the cap base. The function liquid absorber fills the interior of the absorber accommodating portion. The absorber holding member holds the function liquid absorber. The seal securing member secures the sealing member to the cap base. 
     However, since the cap for the ink jet head is arranged such that a peripheral edge of the absorber holding member is held by the sealing member and that the sealing member is secured to the cap base by the seal securing member, a large number of parts is required and a large number of assembling steps is required. Further, when securing the absorber holding member, thermal caulking or an ultrasonic welding may be required. Therefore, for example, dimensional precision of the securing position of the absorber holding member with respect to the cap base is required, thereby lowering production efficiency and preventing cost reduction. 
     SUMMARY 
     The present invention can provide, as one of illustrative, non-limiting embodiment, a capping device for a fluid ejection device, which includes: a cap having a fluid receptacle and a first fluid path; a cap holder supporting the cap and having a second fluid path; and an absorber disposed between and supported by the cap and the cap holder, the absorber having a third fluid path, and in which negative pressure is applicable to the fluid receptacle at least through the first, second and third fluid paths. 
     Accordingly, as one of advantages, the present invention can provide a capping device requiring a smaller number of component parts. As another one of the advantages, the present invention can increase production efficiency of a capping device. As yet another one of the advantages, the present invention can reduce costs of a capping device. 
     These and other advantages of the present invention will be discussed in detail with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic plan view of an internal structure of an ink jet printer including a recovery device including a capping device according to the present invention. 
         FIG. 2  is an enlarged view of an ink jet head as seen in a direction toward a nozzle face. 
         FIG. 3  is a plan view of the capping device according to the present invention. 
         FIG. 4A  is an enlarged sectional view taken along arrow A-A in  FIG. 3 , and  FIG. 4B  is an enlarged sectional view taken along arrow B-B in  FIG. 3 . 
         FIG. 5  is an exploded view illustrating the procedure of assembling the capping device. 
         FIGS. 6A and 6B  illustrate a capping operation of the capping device, with  FIG. 6A  showing a state in which the nozzle face of the ink jet head and a cap are not in contact with each other, and  FIG. 6B  showing a state in which the cap is in contact with the nozzle face. 
         FIG. 7  is an exploded view illustrating another capping device according to the present invention. 
         FIGS. 8A and 8B  illustrate a capping operation of the capping device shown in  FIG. 7 , with  FIG. 8A  showing a state in which a nozzle face of an ink jet head and a cap are not in contact with each other, and  FIG. 8B  showing a state in which the cap is in contact with the nozzle face. 
         FIG. 9  is an exploded view illustrating still another capping device according to the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Illustrative, non-limiting embodiments of the present invention will be described in detail with reference to a capping device for an ink jet head which is one example of a fluid ejection device. 
       FIG. 1  is a schematic plan view of an internal structure of an ink jet printer  100  including a recovery device  11  including a capping device. The ink jet printer  100  includes guide rods  3  and  3  that are provided between portions of a housing  2 , and that support a carriage  9  so that the carriage  9  is slidable in main scanning directions (that is, X directions). An ink jet head  4  is disposed at the carriage  9  so that its nozzle face  4   b , where a plurality of nozzle holes  4   a  are provided, is exposed to the lower side. A platen (not shown) is disposed below the carriage  9 . A sheet-feeding mechanism (not shown) transports a recording medium  6  (such as plain paper) on the platen to sub-scanning directions (that is, Y directions) perpendicular to the main scanning directions, so that the ink jet head  4  ejects ink towards the recording medium  6 . The carriage  9  is driven by a timing belt  8  suspended between a pair of pulleys  7 . A motor (not shown) rotatable in the forward and reverse direction is connected to one of the pulleys  7 . Rotating the pulleys  7  in the forward and reverse direction causes the timing belt  8  to reciprocate, so that the ink jet head  4 , mounted to the carriage  9 , is scanned in the main scanning directions (that is, the X directions) along the guide rods  3 . In the description below, a side to which ink is ejected is defined as the lower side or the downward direction, the opposite side is defined as the upper side or the upward direction, and the scanning directions (that is, the X directions) of the carriage  9  shown in  FIG. 1  are defined as the leftward direction and the rightward direction. Ink cartridges  13  are connected to the ink jet head  4  through respective ink supply tubes  14 , and store a plurality of inks (such as black (BK) ink, yellow (Y) ink, magenta (M) ink, and cyan (C) ink). 
     A flashing receiver  10  that receives ink ejected independently of a recording operation from the nozzle holes  4   a  of the ink jet head  4  is disposed below the guide rods  3  and in a non-printing area at one end in the leftward and rightward direction in the housing  2 . When the ink jet head  4  is positioned above the flashing receiver  10 , ink is periodically or forcibly ejected from the nozzle holes  4   a  to the flashing receiver  10 , so that viscosity-increased ink is discharged from the nozzle holes  4   a  to recover from ejection problems, such as clogging of the nozzle holes  4   a.    
     The recovery device  11  for a purging operation is disposed in another non-printing area at the other end in the leftward and rightward direction. The recovery device  11  is configured to suck ink intentionally or periodically from the nozzle holes  4   a . A wiping member  12  that wipes ink adhered to the nozzle face  4   b  after the purging is provided beside the recovery device  11 . 
     The recovery device  11  performs a recovery operation as follows. By covering the nozzle face  4   b  of the ink jet head  4  with a capping device  1  (see  FIGS. 3 and 4 ), and operating a suction device  15  (see  FIG. 5 ), the pressure in the capping device  1  becomes negative, to discharge air bubbles and viscosity-increased ink, existing in an ink flow path of the ink jet head  4 , from the nozzle holes  4   a , so that the ejection function of the nozzle holes  4   a  is recovered. In addition, the recovery device  11  can prevent drying of the nozzle holes  4   a  and adherence of dust to the nozzle holes  4   a  and the nozzle face  4   b  by covering and protecting the nozzle face  4   b  with the capping device  1  when recording is not performed. 
     As discussed in Japanese Unexamined Patent Application Publication Nos. 2005-322850 and 2005-313428, the ink jet head  4  has a laminated structure having a cavity unit (not shown) and a plate-type piezoelectric actuator (not shown) adhered to the cavity unit. The cavity unit is formed by laminating and adhering a plurality of plates to each other. Ink from the ink cartridges  13  is supplied to the cavity unit. The piezoelectric actuator has a plurality of piezoelectric deformation sections. A flexible wiring member (not shown) to which a driving circuit (not shown) is mounted is disposed on the top surface of the piezoelectric actuator, and is electrically connected to the piezoelectric actuator. The plurality of nozzle holes  4   a  are disposed in the nozzle face  4   b  (which is the lowest surface of the cavity unit) so as to form nozzle arrays in the Y direction according to respective ink colors as shown in  FIG. 2 . Nozzle arrays  4 BK,  4 Y,  4 C, and  4 M are provided in the nozzle face  4   b  so as to be arranged in the X direction (that is, the scanning direction of the carriage  9 ). A print signal from the driving circuit causes the corresponding piezoelectric deformation section to be selectively deformed, so that ink is ejected from the nozzle hole  4   a  corresponding to the deformed piezoelectric deformation section. 
     The recovery device  11  includes the capping device  1 , the suction device  15  (see  FIG. 5 ), a change-over valve  16  (see  FIG. 5 ), suction tubes  18 ,  19 , and  20 , and a raising/lowering device  21  (see  FIG. 6 ). The capping device  1  covers the nozzle face  4   b  by coming into contact with the nozzle face  4   b . The suction device  15  communicates with the capping device  1 , and is used to discharge ink. The change-over valve  16  is used to select ink to be sucked and discharged. The suction tubes  18 ,  19 , and  20  are used to connect the capping device  1  to the suction device  15  through the change-over valve  16 . The raising/lowering device  21 , which is an example of a moving device, is used to move the capping device  1  vertically to cause the capping device  1  to contact the nozzle face  4   b.    
     The capping device  1  includes a cap  30 , a cap holder  50 , and absorbers  70   a  and  70   b . The cap  30  is configured to cover the nozzle face  4   b  of the ink jet head  4 . The cap holder  50  supports the cap  30 . The absorbers  70   a  and  70   b  absorb sucked ink. 
     The cap  30  is rectangular in plan view, and has a substantially recessed form in cross section having an open in upper side. The cap  30  has a cap substrate  32  rectangular in plan view, and a sealing lip  34  that is raised in an annular form at a location situated a short distance inward along the outer peripheral edge of the cap substrate  32  to form a suction chamber  38 . A cap first surface portion of the cap substrate  32 , which is circumscribed by the sealing lip  34 , forms a bottom of the suction chamber  38 . The sealing lip  34  is configured and dimensioned so that the nozzle arrays  4 BK,  4 Y,  4 C, and  4 M of the ink jet head  4  shown in  FIG. 2  are located in the suction chamber  38  when the sealing lip  34  contacts the nozzle face  4   b . A partition lip  36  is provided at the inner side of the sealing lip  34  so as to be parallel to the nozzle arrays  4 BK,  4 Y,  4 C, and  4 M and so as to partition the nozzle array  4 BK from the nozzle arrays  4 Y,  4 C, and  4 M. When the nozzle face  4   b  of the ink jet head  4  is covered with the cap  30 , the suction chamber  38  is partitioned by the partition lip  36  into a suction chamber portion  38   a  and a suction chamber portion  38   b . The suction chamber portion  38   a  corresponds to the nozzle array  4 BK for black ink, and the suction chamber portion  38   b  corresponds to the nozzle arrays  4 Y,  4 C, and  4 M for a plurality of color inks (see  FIGS. 3 and 4 ). The cap substrate  32  of the cap  30  has a substantially rectangular form, in plan view, that is long in the Y direction in correspondence with the nozzle arrays  4 BK,  4 Y,  4 C, and  4 M. The suction chamber portions  38   a  and  38   b  are also substantially rectangular in plan view. 
     The cap  30  has suction openings  40   a  and  40   b  serving as fluid paths and extending through the cap substrate  32 , that is, from the cap first surface portion of the cap substrate  32  forming the bottom of the suction chamber  38  to an opposite surface portion (a cap second surface portion) of the cap substrate  32 . The suction openings  40   a  and  40   b  are located in the bottoms of the respective suction chamber portions  38   a  and  38   b  at longitudinal ends thereof. A suction groove  40   g  is formed in the bottom of the suction chamber portion  38   b  so that the suction groove  40   g  connects to the suction opening  40   b . A total of four protrusions  42  for engagement with through-holes  56  of the cap holder  50  (described later) are formed, two at each of two side surfaces extending in the longitudinal direction of the cap substrate  32  of the cap  30 . The protrusions  42  are disposed near longitudinal end portions of the side surfaces of the cap substrate  32 . 
     The protrusions  42  of the cap  30  are provided for engagement with the through-holes  56  of the cap holder  50 . Therefore, it is possible to provide recesses in place of the protrusions  42  of the cap  30 , and protrusions in place of the through-holes  56  of the cap holder  50 , to engage the cap  30  and the cap holder  50  to each other. 
     The cap  30  is formed of an elastic material, examples of which include rubber materials, such as natural rubber, isoprene rubber, styrene butadiene rubber, butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, ethylene propylene rubber, urethane rubber, silicone rubber, acrylic rubber, chloro sulfonated polyethylene, fluorine rubber, and hydrogenated nitrile rubber. 
     Chips  90   a  and  90   b  having substantially the same shape in plan view as the suction chamber portions  38   a  and  38   b  are inserted in the respective suction chamber portions  38   a  and  38   b  of the cap  30 . The chips  90   a  and  90   b  are rectangular plate members formed of a hard polymeric material, and are provided with guide grooves  92  in surfaces thereof. The guide grooves  92  respectively correspond to the nozzle arrays  4 BK,  4 Y,  4 C, and  4 M and extend to be parallel to the direction of extension of the nozzle arrays  4 BK,  4 Y,  4 C, and  4 M. The chips  90   a  and  90   b  have chip discharge openings  94  that extend through the chips  90   a  and  90   b  in the thickness direction and that are located at longitudinal one ends of the guide grooves  92 . The chip discharge opening  94  of the chip  90   a  communicates with the suction opening  40   a . One of the chip discharge openings  94  of the chip  90   b  communicates directly with the suction opening  40   b , and the other two chip discharge openings  94  of the chip  90   b  communicate through the suction groove  40   g  with the suction opening  40   b . By virtue of this structure, ink discharged from the nozzle holes  4   a  (forming the nozzle arrays  4 BK,  4 Y,  4 C, and  4 M) by a purging operation flows through the guide grooves  92 , is quickly guided to the chip discharge openings  94 , and is guided to the suction openings  40   a  and  40   b  of the suction chamber portions  38   a  and  38   b . Since the chips  90   a  and  90   b  are formed of hard material, and are disposed in close contact with the bottoms of the suction chamber portions  38   a  and  38   b , the chips  90   a  and  90   b  can reinforce the cap substrate  32  when the cap substrate  32  of the cap  30  is deformed due to negative pressure during the purging operation. When the deformation of the cap substrate  32  of the cap  30  is large, deformation, such as the falling of the sealing lip  34  or the partition lip  36 , may cause the nozzle holes  4   a  and the cap  30  to contact each other. However, the existence of the chips  90   a  and  90   b  is effective in restricting the deformation. Since the thickness of the chips  90   a  and  90   b  is sufficiently less than the height of the sealing lip  34  and the height of the partition lip  36  of the cap  30 , even if the sealing lip  34  and the partition lip  36  are in contact with the nozzle face  4   b  during the purging operation, it is possible to prevent the chips  90   a  and  90   b  from contacting the nozzle face  4   b.    
     The cap holder  50  that supports the cap  30  is integrally formed using, for example, hard resin. The cap holder  50  is rectangular in plan view, and has a holder substrate  52  and side walls  54  protruding from the holder substrate  52 . The side walls  54  are formed continuously along two side edges of the holder substrate  52  to extend in the longitudinal direction. The through-holes  56 , to which the protrusions  42  formed at the side surfaces of the cap  30  are fitted, are formed in the side walls  54  so as to extend through the side walls  54  in the X direction (see  FIG. 5 ). When the cap  30  is placed between the side walls  54 , the protrusions  42  of the cap  30  are inserted into and engage the respective through-holes  56 , so that the cap  30  is supported so as not to be inadvertently removed from the cap holder  50 . The through-holes  56  can be replaced by recesses that do not extend through the side walls  54  as long as they can engage the protrusions  42  of the cap  30  so as not to be removed therefrom. As described above, if the protrusions  42  of the cap  30  are replaced by recesses, protrusions are used in place of the through-holes  56  of the cap holder  50 , to make it possible to engage the cap  30  and the cap holder  50 . 
     The holder substrate  52  of the cap holder  50  has accommodating portions  58   a  and  58   b  for accommodating the absorbers  70   a  and  70   b  (described later). Each of the accommodating portions  58   a  and  58   b  is a recessed form open toward a side facing the cap  30 . The accommodating portions  58   a  and  58   b  are rectangular and substantially as large as the suction chamber portions  38   a  and  38   b  of the cap  30  in a plan view. Since the accommodating portions  58   a  and  58   b  are recessed from an upper surface of the holder substrate  52  and the side walls  54  protrudes from the upper surface of the holder substrate  52  at locations outward from the accommodating portions  58   a  and  58   b , steps are formed between the accommodating portions  58   a  and  58   b  and the side walls  54 . Discharge openings  62   a  and  62   b , serving as fluid paths, extend through an accommodating bottom surface  60  of the holder substrate  52  in the thickness, that is, from a holder first surface portion of the holder  50  facing the cap  30  to an opposite surface portion (a holder second surface portion) of the holder  50 . The discharge openings  62   a  and  62   b  are respectively located at longitudinal one ends of the accommodating portions  58   a  and  58   b  so as to correspond in position to the suction openings  40   a  and  40   b  of the cap  30 . Connection portions  64   a  and  64   b  protrude downward from the holder second surface portion of the holder  50  to connect to the suction tubes  18  and  19  for communication of the discharge openings  62   a  and  62   b  with the suction tubes  18  and  19 . Although the discharge openings  62   a  and  62   b  of the holder  50  and the suction openings  40   a  and  40   b  of the cap  30  are disposed in the same longitudinal end, they may be disposed at opposite longitudinal end as shown in  FIG. 9 . 
     The absorbers  70   a  and  70   b  are each in the form of a plate member that is formed of porous material, such as sponge, and that is rectangular in plan view. The absorbers  70   a  and  70   b  are accommodated in close contact with the inner surfaces of the accommodating portions  58   a  and  58   b  of the cap holder  50 . At least one guide path  72   a  and at least one guide path  72   b  are provided in the respective absorbers  70   a  and  70   b  so as to extend through the respective absorbers  70   a  and  70   b  in the thickness direction thereof. The guide paths  72   a  and  72   b  connect the suction openings  40   a  and  40   b  of the cap  30  to the discharge openings  62   a  and  62   b  of the cap holder  50 . The suction openings  40   a  and  40   b  oppose the respective discharge openings  62   a  and  62   b  with the respective absorbers  70   a  and  70   b  being disposed therebetween. As illustrated, the suction opening  40   a ,  40   b , the guide path  72   a ,  72   b  and the discharge opening  62   a ,  62   b  are aligned on a line, respectively. Therefore, ink discharged from the nozzle holes  4   a  during a purging operation flows through the guide paths  72   a  and  72   b  from the suction openings  40   a  and  40   b , and is quickly guided to the discharge openings  62   a  and  62   b , while a portion of the ink is absorbed by the absorbers  70   a  and  70   b . Consequently, the ink is discharged with good efficiency. 
     Although the cap  30  is formed so that the nozzle array  4 BK, which ejects black ink, and the nozzle arrays  4 Y,  4 C, and  4 M, which eject color inks, are covered by the suction chamber portions  38   a  and  38   b , respectively, it may be formed so that all of the nozzle arrays are covered only by the sealing lip  34  without providing the partition lip  36 . In this case, the chip  90  and the absorber  70  are no longer required to be divided into two members, and, the accommodating portion  58  of the cap holder  50  does not need to be divided into two portions. Therefore, the structure can be simplified, thereby facilitating designing and manufacturing. 
     Next, a procedure of assembling the capping device  1  will be described. 
     Absorbers  70   a  and  70   b  in which the guide paths  72   a  and  72   b  are preliminarily formed are accommodated in respective accommodating portions  58   a  and  58   b  of a cap holder  50 . Here, the guide paths  72   a  and  72   b  of the respective absorbers  70   a  and  70   b  are disposed so as to oppose discharge openings  62   a  and  62   b  of the cap holder  50 , respectively. A cap  30  is disposed so that suction openings  40   a  and  40   b  oppose the discharge openings  62   a  and  62   b  of the cap holder  50  with the absorbers  70   a  and  70   b  being disposed therebetween. Protrusions  42  are fitted to through-holes  56  of the cap holder  50 , so that the cap  30  is fitted into the cap holder  50 . This causes a lower surface portion (a cap second surface portion) of a cap substrate  32  of the cap  30  to closely contact an upper surface portion (a holder first surface portion) of a holder substrate  52  of the cap holder  50  around the accommodating portions  58   a  and  58   b , so that accommodating portions  58   a  and  58   b  of the cap holder  50  are sealingly covered by the cap  30 . This causes the interior of the accommodating portions  58   a  and  58   b  to be in a hermetically sealed state, so that the humidity in the accommodating portions  58   a  and  58   b  can be maintained over a long period of time. Parts for securing only the absorbers  70   a  and  70   b  are no longer required, so that the number of assembly man-hours can be reduced. In this connection, the lower surface portion (the cap second surface portion) of the cap substrate  32  of the cap  30  also closely contact an upper surfaces of the absorbers  70   a  and  70   b  so that the absorbers  70   a  and  70   b  are slightly compressed by the lower surface portion (the cap second surface portion) of the cap substrate  32  and bottom surfaces of the accommodating portions  58   a  and  58   b . Then, chips  90   a  and  90   b  are inserted into suction chamber portions  38   a  and  38   b  of the cap  30  so that chip discharge openings  94  communicate with the suction openings  40   a  and  40   b  of the cap  30  directly or through the suction groove  40   g . In the assembly procedure, it is possible to fit the cap  30  into the cap holder  50  after inserting the chips  90   a  and  90   b  into the cap  30 . 
     The capping device  1  is so designed that the sealing lip  34  of the cap  30  protrudes by a greater amount than the side walls  54  of the cap holder  50 , and the upper surfaces of the chips  90   a  and  90   b  are lower than the upper surface of the sealing lip  34  of the cap  30 . Therefore, even if the cap  30  contacts the nozzle face  4   b  of the ink jet head  4 , the cap holder  50  and the chips  90   a  and  90   b  are not in contact with the nozzle face  4   b . Therefore, it is possible to prevent ejection problems and damage to the nozzle holes  4   a.    
     The form of the capping device  1  is not limited to a rectangular form that is long in the sub-scanning directions (Y directions) in plan view. It is possible to increase the width, so that the capping device  1  covers a wider range of the nozzle face  4   b  of the ink jet head  4 . 
     The operation of the recovery device  11  including the capping device  1  will be described. The suction device  15  ( FIG. 5 ) of the recovery device  11  is connected to the change-over valve  16  through the suction tube  20 , and the change-over valve  16  is connected to the capping device  1  through the suction tubes  18  and  19 . 
     First, the carriage  9  to which the ink jet head  4  is mounted is driven, and moved to a position where the nozzle face  4   b  opposes the capping device  1 . Then, the capping device  1  is moved towards the ink jet head  4  by the moving device, such as raising/lowering device  21 , to cause an end of the sealing lip  34  and an end of the partition lip  36  of the cap  30  to contact the nozzle face  4   b . This causes the nozzle array  4 BK for black ink and the nozzle arrays  4 Y,  4 C, and  4 M for color inks to be covered by the respective suction chamber portions  38   a  and  38   b.    
     The change-over valve  16  is switched to a position causing the capping device  1  and the suction device  15  to communicate with each other. The suction device  15  is driven in a state in which the capping device  1  is sealed by the nozzle face  4   b . By causing the pressure in the capping device  1  to be negative, i.e. by applying a negative pressure to the capping device  1 , air bubbles or viscosity-increased ink in the ink jet head  4  is sucked from the nozzle holes  4   a  through the capping device  1 . Since the suction openings  40   a  and  40   b  of the cap  30 , the respective guide paths  72   a  and  72   b  of the absorbers  70   a  and  70   b , and the respective discharge openings  62   a  and  62   b  of the cap holder  50  are arranged in straight lines, negative pressure smoothly acts upon the entire interior of the cap  30 . 
     Ink sucked from the nozzles  4   a  is sucked to the suction openings  40   a  and  40   b  of the cap  30  through the guide grooves  92  and the suction groove  40   g , and also through a very small gap between the cap  30  and the chips  90   a  and  90   b  by capillary phenomenon. The sucked ink flows to the guide paths  72   a  and  72   b  of the respective absorbers  70   a  and  70   b , so that a portion of the ink is absorbed by the absorbers  70   a  and  70   b , while the remaining ink that was not absorbed by the absorbers  70   a  and  70   b  is discharged outside the capping device  1  through the discharge openings  62   a  and  62   b  of the cap holder  50 , and is transported to a waste-liquid reservoir (not shown). 
     When the ink jet head  4  is not used, such as when the ink jet head  4  is in a non-recording state and purging is not performed, the change-over valve  16  is switched to a closed state to break the communication between the capping device  1  and the suction device  15 , and the capping device  1  is brought into contact with the nozzle face  4   b , thereby forming a hermetically sealed space in the cap  30 . That is, by covering the nozzle face  4   b  with the capping device  1  and shielding the nozzle holes  4   a  from the atmosphere, it is possible to prevent, for example, dust from adhering to the nozzle holes  4   a . Further, since a suitable amount of ink is absorbed by the absorbers  70   a  and  70   b , the nozzle holes  4   a  can be maintained in a moisture retention state. Furthermore, pushing force generated by the raising/lowering device  21  to contact the cap  30  with the nozzle face  4   b  also act on the cap  30  and the cap holder  50 . Consequently, the accommodating portions  58   a  and  58   d  also become hermetically sealed spaces. This also makes it possible to maintain a moisture retention state. 
     A capping device  1 ′ and a capping device  1 ″ will be described with reference to  FIGS. 7 to 9 . In  FIGS. 7 to 9 , similar or corresponding structural features to those in the capping device  1  will be given the same reference numerals. The illustrations do not show a raising/lowering device  21 . 
     In case of the capping device  1 ′, the forms of accommodating portions  58   a  and  58   b  of a cap holder  50  accommodating absorbers  70   a  and  70   b  are different. That is, as shown in  FIG. 7 , an annular wall  66  is provided in a standing manner so as to be rectangular in plan view on the upper surface of an accommodating bottom surface  60  of the cap holder  50 ; the inner side of the annular wall  66  is divided in two by a partition wall  68 ; and these divided portions are defined as the accommodating portions  58   a  and  58   b  that accommodate the absorbers  70   a  and  70   b . A cap  30  is fitted to the cap holder  50  with a lower surface of a cap substrate  32  being in close contact with an upper surface of the annular wall  66  and an upper surface of the partition wall  68  while the absorbers  70   a  and  70   b  are accommodated in the respective accommodating portions  58   a  and  58   b.    
     As shown in  FIG. 8B , the capping device  1 ′ is so designed that when the cap  30  comes into contact with a nozzle face  4   b , a pushing force resulting therefrom causes the lower surface of the cap substrate  32  of the cap  30  and the upper surface of the annular wall  66  to be in close contact with each other. Therefore, in a purging operation, the sealing properties of the interiors of the accommodating portions  58   a  and  58   b  are ensured, so that ink can be efficiently discharged. In addition, the suction groove  40   g  of the capping device  1 ′ is so designed that a bottom surface of the suction groove  40   g  is inclined downward toward the suction opening  40   b  in order to facilitate ink flow toward the suction opening  40   b  during purging operation. In this connection, although suction groove  40   g  is formed in the cap  30  in the capping devices  1  and  1 ′, the suction groove  40   g  may be formed in the chip  90   b  or may be formed in both the cap  30  and the chip  90   b.    
     Further, as shown in  FIGS. 8A and 8B , the absorbers  70   a  and  70   b  are so dimensioned that a gap is formed between the absorber  70   a ,  70   b  and the lower surface of the cap  30  when the absorber  70   a ,  70   b  is accommodated in the accommodating portion  58   a ,  58   b.    
     In case of a capping device  1 ″, the forms of guide paths  72   a ′ and  72   b ′ of absorbers  70   a  and  70   b  are different. That is, as shown in  FIG. 9 , when suction openings  40   a  and  40   b  of a cap  30  and discharge openings  62   a ′ and  62   b ′ of a cap holder  50  are positioned at opposite sides in the longitudinal direction, guide paths  72   a ′ and  72   b ′ of absorbers  70   a  and  70   b  are provided by forming cutaway portions in a range including the suction openings  40   a  and  40   b  and the discharge openings  62   a ′ and  62   b ′ in plan view (that is, extending so as to connect the suction openings and the discharge openings). These cutaway portions extend through the absorbers  70   a  and  70   b  in the longitudinal direction. Accordingly, when the guide paths  72   a ′ and  72   b ′ are formed as cutaway portions, suction during a purging operation is not hampered, and the absorbers  70   a  and  70   b  are easily formed, so that they can be formed as appropriate in accordance with the design of the cap  30  and the cap holder  50 . 
     As described above, an accommodating portion that accommodate an absorber is formed in a cap holder, and a cap is supported by the cap holder by engaging the cap holder with the cap, to thereby hold the absorber in the accommodating portion. Therefore, it is possible to provide a capping device for an ink jet head, which has a simple structure, has few parts, and is easily assembled. In addition, a guide path that connects a suction opening and a discharge opening extends through the absorber. Therefore, liquid is quickly guided to the discharge opening, so that discharging efficiency can be increased. 
     The present invention can provide the following illustrative, non-limiting embodiments: 
     (1) A capping device for an ink jet head, include: a cap that is configured to cover a nozzle face of the ink jet head; a cap holder that supports the cap from a side opposite from the ink jet head; and an absorber. The absorber is held between the cap and the cap holder. The cap has a suction opening extending through the cap from a side of the nozzle face toward the side opposite from the ink jet head. The cap holder has a discharge opening extending through the cap holder from a side of the absorber to a back-surface side of the cap holder. The absorber has a guide path extending through the absorber in a thickness direction. The guide path connects the suction opening and the discharge opening to each other, and discharges liquid from the suction opening to the discharge opening. 
     According to the capping device of (1), the absorber is held between the cap and the cap holder, and therefore a part that secures only the absorber is no longer required. Therefore, assembly can be performed without performing steps, such as a thermal caulking step or an ultrasonic adhesion step, for securing this part. In addition, since the guide path extends through and is provided at the absorber so as to connect the suction opening and the discharge opening to each other, a portion of the liquid sucked in the cap from the nozzle hole of the ink jet head is guided to the guide path and discharged from the discharge opening, and the remaining liquid is absorbed by the absorber. Therefore, the liquid existing in the cap can be smoothly guided to the discharge opening. Further, the existence of the absorber allows more liquid existing in the cap to be discharged from the interior of the cap. 
     Since the number of parts assembly steps is reduced, production efficiency can be increased, and costs can be reduced. In addition, since the nozzle hole of the ink jet head can be maintained in a good state, a high quality image can be maintained. 
     (2) In the capping device of (1), the cap has a substrate and a sealing lip having a substantially recessed form in cross section. The substrate is rectangular in plan view and has a cap bottom surface provided opposite to the nozzle face. The sealing lip opens at the side of the nozzle face, is raised in an annular form, and contacts the nozzle face to cover a nozzle hole. The cap holder has a bottom portion and side walls. The bottom portion of the cap holder faces the bottom surface of the cap through the absorber. The side walls are raised from the bottom portion of the cap holder to extend along side surfaces of the substrate. The cap is fitted and mounted between the side walls. 
     According to the capping device of (2), the cap can be supported by the cap holder by fitting the cap between the side walls, and therefore the cap is easily assembled to the cap holder. 
     Since the absorber is easily assembled, production efficiency can be increased. 
     (3) In the capping device of (2), the bottom portion of the cap holder has an accommodating portion that opens to a side of the cap and that accommodates the absorber. The cap is mounted to the cap holder to cover the open side of the accommodating portion by the bottom surface of the cap. 
     According to the capping device (3), the absorber can be easily accommodated in the cap holder. In addition, if the cap is assembled to the cap holder, the absorber can be secured by the cap. Therefore, a part and a step for securing only the absorber are no longer required. Further, since the sealing property in the accommodating portion is ensured, the humidity in the accommodating portion can be maintained for a long period of time. 
     Since the absorber can be easily accommodated in the cap holder and the humidity in the accommodating portion can be maintained, the nozzle hole can be maintained in a good state over a long period of time. 
     (4) In the capping device of (3), a recess is provided in the bottom portion of the cap holder, and the open side of the accommodating portion is covered by bringing the bottom portion of the cap and the bottom surface of the cap holder into contact with each other. 
     According to the capping device of (4), the absorber can be easily accommodated in the cap holder. In addition, the bottom surface of the cap can secure the entire absorber. 
     Using a simple structure, the absorber can be accommodated in the cap holder, so that it can be easily secured. 
     (5) In the capping device of (3), the accommodating portion is disposed by raising an annular wall from the bottom portion of the cap holder toward the cap, and the open side of the accommodating portion is covered by bringing the bottom surface of the cap and a top end of the annular wall into contact with each other. 
     According to the capping device of (5), the absorber can be accommodated in the cap holder using a simple structure. In addition, the bottom surface of the cap can secure the entire absorber. 
     Using a simple structure, the absorber can be accommodated in the cap holder, so that it can be easily secured. 
     (6) In the capping device of (2), one of the side wall and the substrate opposing the side wall is provided with a protrusion that is fitted in a direction intersecting a direction in which the cap is fitted into the cap holder, and the other of the side wall and the substrate is provided with a recess or a through-hole that is fitted in the direction intersecting the direction in which the cap is fitted into the cap holder. 
     According to the capping device of (6), the cap can be prevented from being inadvertently removed from the cap holder. 
     Since the cap is not inadvertently removed from the cap holder, reliability can be increased. 
     (7) In the capping device of (1), the suction opening and the discharge opening are disposed opposite to each other with the guide path being disposed therebetween. 
     According to the capping device of (7), the distance between the suction opening and the discharge opening is reduced, so that discharging of the liquid in the cap from the discharge opening is facilitated. 
     The ink jet head can be smoothly maintained without making the structure of the absorber complicated. 
     (8) In the capping device of (1), the guide path is disposed by extending through the absorber in a direction in which the suction opening and the discharge opening are connected to each other. 
     According to the capping device (8), the suction opening and the discharge opening need not oppose each other, so that the degree of freedom with which the cap and the cap holder are designed is increased. 
     (9) In the capping device of (2), the nozzle face is provided with a plurality of nozzle holes disposed in an array, a chip having a guide groove is disposed within the sealing lip. The guide groove guides the liquid along a direction of the array of the nozzle holes. In addition, the liquid that has passed along the guide groove is guided to the suction opening. 
     According to the capping device of (9), the liquid can be prevented from remaining in the cap by disposing the chip, having the guide groove, within the sealing lip. 
     Since the liquid is prevented from remaining in the cap, discharge failure, caused by adherence of remaining liquid to the nozzle face, can be prevented from occurring. 
     (10) A recovery device includes: the capping device of any one of (1) to (9); a raising/lowering device for bringing the cap into contact with the nozzle face; and a suction device for sucking the liquid from the ink jet head. The suction device is connected to the discharge opening, and the liquid is sucked from the suction opening to the discharge opening through the guide path. 
     According to the recovery device of (10), the parts assembly steps are simplified. In addition, pushing force that is generated by bringing the cap into contact with the nozzle face by the raising/lowering device pushes the cap and the cap holder. Therefore, the interior of the accommodating portion is in a sealed state, so that the sealing property in the accommodating portion is ensured. Consequently, the humidity in the accommodating portion can be maintained for a long period of time. 
     The recovery device of (10) makes it possible to provide a liquid discharging apparatus which can increase production efficiency and which can maintain good image quality.