Patent Publication Number: US-7712864-B2

Title: Apparatus and method for maintaining recording head

Description:
The present application is based on Japanese Patent Application No. 2004-313327 filed on Oct. 28, 2004, the contents of which are incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an apparatus and a method for maintaining a recording head of a recording device that ejects, from a nozzle of the head, a droplet of ink toward a recording medium and thereby records an image on the medium, such that the recording head is separate from a remaining portion of the recording device. 
   2. Discussion of Related Art 
   When a recording head is not used, or before the recording head is attached to a recording device after the head is manufactured, the recording head may be maintained separate from the recording device. For instance, the recording head can be charged with ink or a suitable liquid. Drying or leakage of the ink or the liquid is prevented by air-tightly sealing, with a sealing member (e.g., a cap) formed of an elastic material such as rubber, a nozzle-defining surface of the recording head that defines one or more ink ejection nozzles, as taught by Japanese Patent No. 3,324,629 or its corresponding U.S. Pat. No. 5,805,181A. 
   More specifically described, the above-indicated document teaches selectively using a monochromatic-image recording head or a full-color-image recording head, mounting the recording head selected, on a carriage, and maintaining the recording head not selected, in a state in which the recording head is charged with one or more sorts of ink. Meanwhile, after a recording head is manufactured, the recording head may be subjected to an ejection test, and the head that has passed the test may be maintained in a state in which the head is charged with one or more sorts of ink, or a suitable liquid, before the head is attached to a remaining portion of a recording device. 
   A recording head cannot normally eject a droplet of ink unless a meniscus of the ink is normally formed, owing to its surface tension, in the vicinity of an open end of a nozzle. Thus, in the state in which the recording head is maintained, it is required that the meniscus of the ink be formed at the normal position and that the nozzle-defining surface of the recording head be air-tightly sealed. 
   SUMMARY OF TH INVENTION 
   However, when the nozzle-defining surface of the recording head is covered with a sealing member, the sealing member may be elastically deformed so that a space formed between the nozzle-defining surface and the sealing member may be compressed and accordingly an air pressure in the space may be increased, and accordingly the meniscus of the ink in the nozzle may be broken. 
   The above-indicated document proposes a sealing method in which the above-described air-tight space is communicated with the atmosphere via a flow-resisting passage. However, since the flow-resisting passage has a considerably great resistance for the purpose of preventing drying of the ink, the passage cannot follow the change of volume of the space when the sealing member is attached to the nozzle-defining surface. Thus, the meniscus of the ink may be subjected to a high air pressure, and accordingly it may be broken. In addition, since the space defined by the sealing member is always communicated with the atmosphere, the drying of the ink cannot be effectively prevented. 
   It is therefore an object of the present invention to solve at least one of the above-indicated problems. It is another object of the present invention to provide a recording-head maintaining apparatus and a recording-head maintaining method each of which can maintain a nozzle in an air-tight state and thereby prevent drying of an ink or a liquid in the nozzle, without breaking a meniscus of the ink. 
   The above objects may be achieved according to the present invention. According to a first aspect of the present invention, there is provided an apparatus for maintaining a recording head which has a nozzle opening in a nozzle-defining surface thereof, and ejects, from the nozzle, a droplet of an ink toward a recording medium, in a state in which the recording head is separate from a remaining portion of a recording device. The apparatus comprises a cover member which is adapted to air-tightly contact the recording head to cover the nozzle-defining surface of the recording head such that a space is formed between the cover member and nozzle-defining surface. The apparatus further comprises a selectively communicating means which can selectively take (a) a first state thereof in which the selectively communicating means allows the space to communicate with an atmosphere so that substantially no difference is produced between an air pressure in the space and an atmospheric pressure, when the cover member is air-tightly contacted with the recording head; and (b) a second state thereof in which the selectively communicating means shuts off a communication between the space and the atmosphere, and thereby air-tightly closes the space, after the cover member is air-tightly contacted with the recording head. 
   The present recording-head maintaining apparatus includes the selectively communicating means which allows the space formed between the cover member and the nozzle-defining surface when the cover member covers the nozzle-defining surface, to communicate with the atmosphere. Therefore, when the cover member covers the nozzle-defining surface, a certain amount of air is discharged from the space into the atmosphere. Thus, the air pressure in the space can be prevented from being excessively increased, and accordingly a meniscus of the ink present in the nozzle can be reliably prevented from being broken. 
   In addition, the selectively communicating means air-tightly closes the communication between the space and the atmosphere and thereby shuts off the space from the atmosphere. Thus, the nozzle can be kept in the air-tight state and accordingly drying of the ink (or a different liquid) present in the nozzle can be effectively prevented. 
   According to a second aspect of the present invention, there is provided a method of maintaining a recording head which has a nozzle opening in a nozzle-defining surface thereof, and ejects, from the nozzle, a droplet of an ink toward a recording medium, in a state in which the recording head is separate from a remaining portion of a recording device and a cover member covers the nozzle-defining surface such that a space is formed between the cover member and the nozzle-defining surface. The method comprises keeping, when the cover member is air-tightly contacted with the recording head, a communication between the space and an atmosphere so that substantially no difference is produced between an air pressure in the space and an atmospheric pressure. The method further comprises shutting off, after the cover member is air-tightly contacted with the recording head, the communication between the space and the atmosphere, so that the space is air-tightly closed during a time period in which the cover member is air-tightly contacted with the recording head. 
   In the present recording-head maintaining method, the space formed between the cover member and the nozzle-defining surface is communicated with the atmosphere through the one or more through-holes, before the cover member is air-tightly contacted with the recording head. When the cover member covers the nozzle-defining surface, a certain amount of air is discharged from the space into the atmosphere through the through-hole or through-holes. Thus, the air pressure in the space can be prevented from being excessively increased, and accordingly a meniscus of the ink present in the nozzle can be reliably prevented from being broken. 
   In addition, after the cover member is air-tightly contacted with the recording head, the communication between the space and the atmosphere is shut off to keep the nozzle in the air-tight state. Thus, drying of the ink (or a different liquid) present in the nozzle can be effectively prevented. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and optional objects, features, and advantages of the present invention will be better understood by reading the following detailed description of the preferred embodiments of the invention when considered in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a plan view of an inkjet recording device including a recording head that can be maintained by a recording-head maintaining apparatus as a first embodiment of the present invention; 
       FIG. 2  is a longitudinal cross-section view of the recording head and a head holder holding the recording head; 
       FIG. 3  is a bottom view of the head holder and the recording head held by the head holder; 
       FIG. 4A  is a longitudinal cross-section view of the recording-head maintaining apparatus in a state thereof before a “nozzle” surface  31   a  of the recording head is sealed; 
       FIG. 4B  is a plan view of a sealing member of the recording-head maintaining apparatus; 
       FIG. 4C  is a side elevation view of a protector member of the recording-head maintaining apparatus, as seen along C-C in  FIG. 4A ; 
       FIG. 5A  is a partly cross-sectioned, side elevation view of the recording-head maintaining apparatus in a state thereof after the nozzle surface is sealed; 
       FIG. 5B  is a longitudinal cross-section view of respective engaging portions of an upper case and a lower case of the recording-head maintaining apparatus; 
       FIG. 6A  is a partly cross-sectioned, side elevation view of a device for forming, with two needle-like members, two through-holes through a thickness of another sealing member of another recording-head maintaining apparatus as a second embodiment of the present invention; 
       FIG. 6B  is a plan view of the sealing member shown in  FIG. 6A ; 
       FIG. 7A  is a partly cross-sectioned, side elevation view of an upper case of the recording-head maintaining apparatus of  FIG. 6A ; 
       FIG. 7B  is a side elevation view of a protector member of the recording-head maintaining apparatus of  FIG. 6A ; 
       FIG. 7C  is a partly cross-sectioned, side elevation view of a head holder holding a recording-head; 
       FIG. 7D  is a partly cross-sectioned, side elevation view of the lower case of the recording-head maintaining apparatus of  FIG. 6A  in a state thereof in which the sealing member is penetrated by the two needle-like members; 
       FIG. 8  is a partly cross-sectioned, side elevation view of the recording-head maintaining apparatus of  FIG. 6A  in a state thereof in which the maintaining apparatus holds the head holder holding the recording head; 
       FIG. 9  is a view for illustrating a manner in which the recording-head maintaining apparatus of  FIG. 6A  is separated from an operation table; 
       FIG. 10  is a partly cross-sectioned, side elevation view of a device for forming, with two needle-like members, two through-holes through a thickness of another sealing member of another recording-head maintaining apparatus as a third embodiment of the present invention; 
       FIG. 11A  is a partly cross-sectioned, side elevation view of an upper case of the recording-head maintaining apparatus of  FIG. 10 ; 
       FIG. 11B  is a side elevation view of a protector member of the recording-head maintaining apparatus of  FIG. 10 ; 
       FIG. 11C  is a partly cross-sectioned, side elevation view of a head holder holding a recording head; 
       FIG. 11D  is a partly cross-sectioned, side elevation view of a lower case of the recording-head maintaining apparatus of  FIG. 10  in a state thereof in which the two through-holes are formed through the sealing member by the two needle-like members; 
       FIG. 12  is a view of a sealing plug that is formed as an integral portion of a lower case of another recording-head maintaining apparatus as a fourth embodiment of the present invention; 
       FIG. 13  is a view of another sealing plug that is formed as an integral portion of another sealing member of another recording-head maintaining apparatus as a fifth embodiment of the present invention; and 
       FIG. 14  is a view of a packing material that closes a communication hole formed through a thickness of another sealing member of another recording-head maintaining apparatus as a sixth embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   First Embodiment 
   Hereinafter, there will be described a first embodiment of the present invention by reference to  FIGS. 1 through 3 ,  4 A,  4 B,  4 C,  5 A, and  5 B. 
   Construction of Inkjet Printer  1   
     FIG. 1  is a plan view showing a construction of an inkjet recording device, i.e., an inkjet printer  1  including a recording head, i.e., an inkjet head  30  that may be maintained by a recording-head maintaining apparatus  100  ( FIGS. 4A and 5A ) to which the present invention is applied. 
   In an inner space of the inkjet printer  1 , two guide bars  6 ,  7  are provided, and a head holder  9  functioning as a carriage is supported by the two guide bars  6 ,  7 . The head holder  9  holds the inkjet head  30  that ejects droplets of inks toward a recording sheet, P, as a sort of recording medium and records an image on the recording sheet P. The head holder  9  is secured to an endless belt  11  that is circulated by an electric motor  10  and, when the motor  10  is driven or operated, the head holder  9  is moved on the guide bars  6 ,  7 . A known belt-like timing indicator, not shown, is provided along the guide bar  7 . The timing indicator has a number of timing marks that are used to detect a current position of the head holder  9 . 
   In addition, on a stationary member, not shown, provided in the inner space of the inkjet printer  1 , there are provided four ink tanks  5 , i.e., an ink tank  5   a  that stores a yellow ink (Y), an ink tank  5   b  that stores a magenta ink (M), an ink tank  5   c  that stores a cyan ink (C), and an ink tank  5   d  that stores a black ink (BK). The four ink tanks  5   a ,  5   b ,  5   c ,  5   d  are connected via respective flexible ink supply tubes  14   a ,  14   b ,  14   c ,  14   d  to a tube joint  20  ( FIG. 2 ). 
   In the vicinity of one of opposite ends of a movement range in which the head holder  9  can be moved, there is provided a flushing portion  12 ; and in the vicinity of the other end of the movement range of the head holder  9 , there is provided a maintenance portion  4 . The inkjet head  30  can be operated to eject bad inks containing air bubbles, toward the flushing portion  12 , and thereby keep its own good ink-ejecting performance. The maintenance portion  4  can be operated to suck the bad inks from the inkjet head  30  and wipe a “nozzle” surface (i.e., a nozzle-defining surface)  31   a  ( FIG. 2 ) of the head  30 , and thereby keep the good ink-ejecting performance of the head  30 . 
   Construction of Head Holder  9   
   Next, there will be described a construction of the head holder  9  that holds the inkjet head  30 , by reference to  FIGS. 2 and 3 . In the following description, it is assumed that a surface of the head holder  9  from which droplets of inks are ejected will be referred to as the “lower” surface of the holder  9 . The opposite surface of the holder  9  will be referred to as the “upper” surface of the holder  9 . A direction in which the droplets of inks are ejected from the holder  9  will be referred to as the “downward” direction, and an opposite direction will be referred to as the “upward” direction. In addition, it is assumed that a direction toward a left-hand end of  FIG. 1  will be referred to as the “leftward” direction. The direction opposite “leftward”will be referred to as the“rightward” direction, a direction toward a lower end of  FIG. 1  will be referred to as the “frontward” direction, and a direction opposite to the frontward direction will be referred to as the“rearward” direction. 
   In a state in which the tube joint  20  is removed from the buffer tank  40 , that is, in a recording-head maintaining state, described later, a protector member  21  ( FIG. 4A ) is detachably attached to the buffer tank  40  so as to close the four connection ports  40   f  of the buffer tank  40 . 
   As shown in  FIG. 2 , the head holder  9  has a box-like shape, and the inkjet head  30  is held by a bottom wall  9   e  of the holder  9 . 
   As shown in  FIGS. 2 and 3 , the inkjet head  30  includes a cavity portion  31  having a plurality of ink flow channels, not shown, and a piezoelectric actuator  32  that applies an ejection pressure to ink present in an arbitrary one of the ink flow channels and is stacked on the cavity portion  31 . The cavity portion  31  has, in the nozzle surface  31   a  as the lower surface thereof, four arrays of nozzles, i.e., an array of nozzles  35  corresponding to the yellow ink, an array of nozzles  36  corresponding to the magenta ink, an array of nozzles  37  corresponding to the cyan ink, and two arrays of nozzles  38  corresponding to the black ink. In addition, the cavity portion  31  has, in the upper surface thereof, four ink inlet ports  31   b  corresponding to the four color inks, respectively. 
   As shown in  FIG. 2 , a reinforcing frame  33  is fixed, by adhesion, to an upper surface of the inkjet head  30 . The reinforcing frame  33  has four ink flow holes  33   a  corresponding to the four ink inlet ports  31   b , respectively. A unit consisting the inkjet head  30  and the reinforcing frame  33  is provided along the lower surface of the bottom wall  9   e , and is fixed, with an adhesive, to the bottom wall  9   e.    
   The head holder  9  has, in a space located above the bottom wall  9   e  thereof, i.e., above the inkjet head  30  that faces the recording sheet P in the downward direction, a buffer tank  40  that has four ink delivering portions  40   a  that correspond to the four color inks, respectively, and are separated from each other by partition walls, not shown. The four ink delivering portions  40   a  have, in a lower surface of the buffer tank  40 , respective ink supply ports  40   e  that communicate with the four ink inlet ports  31   b  via the respective ink flow holes  33   a.    
   Respective upper open ends of the four ink delivering portions  40   a  are closed by a flexible membrane member  41 . More specifically described, the membrane member  41  is formed of a resin-based film, and is fixed, by adhesion or supersonic welding, to respective upper ends of the partition walls that separate the four ink delivering portions  40   a  from each other, and an upper end of an outer wall of the buffer tank  40 . As known in the art, a predetermined amount of air is accumulated in an upper end portion of each of the four ink delivering portions  40   a . The predetermined amount of air cooperates with the flexible membrane  41  to absorb changes of pressure of a corresponding one of the four color inks that are caused when the inkjet head  30  is moved with the head holder  9  as the movable carriage. An excessive amount of air over the predetermined amount of air accumulated in the upper end portion of each ink delivering portion  40   a  is discharged into an outside space by an air discharging device  45  ( FIG. 3 ) that is provided on a side surface of the buffer tank  40 . 
   A front end portion of the head holder  9  includes, as an integral portion thereof an arm portion  9   a  that extends horizontally in the frontward direction, and a front end portion of the buffer tank  40  includes an extension portion that extends parallel to the arm portion  9   a  such that the extension portion is superposed on the arm portion  9   a . The tube joint  20  is connected to the extension portion of the buffer tank  40 . 
   The four flexible tubes  14   a  through  14   d  ( FIG. 1 ) that are connected, at respective one ends thereof, to the four ink tanks  5   a  through  5   d  are connected, at the respective other ends thereof, to the tube joint  20 . The tube joint  20  is detachably attached to the extension portion of the buffer tank  40 , and has four communication passages, not shown, that communicate with the four tubes  14   a  through  14   d , respectively. The buffer tank  40  has four connection ports  40   f  that communicate with the four ink delivering portions  40   a  and open in an upper surface of the extension portion. The four communication passages of the tube joint  20  communicate with the four connection ports  40   f  of the buffer tank  40 , respectively, so that the four ink tanks  5   a  through  5   d  can supply the four color inks to the four ink delivering portions  40   a , respectively. 
   In a state in which the tube joint  20  is removed from the buffer tank  40 , that is, in a recording-head maintaining state, described later, a protector member  21   FIG. 4A ) is detachably attached to the buffer tank  40  so as to close the four connection ports  40   f  of the same  40 . 
   The tube joint  20  includes, as a front end portion thereof, a holding projection  29  having a slit  29   a  through which a flexible flat cable, not shown, is inserted. Thus, the holding projection  29  supports the flat cable. The flat cable electrically connects an electric-circuit substrate  84 , described below, to a control device, not shown, that is provided on a stationary member provided in the inner space of the inkjet printer  1 . 
   The circuit substrate  84  is a rigid member, and is provided on an upper open end of the head holder  9  such that the substrate  84  is opposite to the inkjet head  30  with respect to the buffer tank  40 . More specifically described, the circuit substrate  84  is detachably attached to the holder  9  such that the substrate  84  is supported by the respective upper ends of the walls of the head holder  9 . 
   A cover member  9   d  is provided over the circuit substrate  84 . Since the cover member  9   d  has a box-like shape opening in the downward direction, the cover member  9   d  can externally cover the upper open end of the head holder  9 . 
   Construction of Head Maintaining Apparatus  100   
   Next, there will be described a construction of the recording-head maintaining apparatus  100  that maintains the inkjet head  30 , by reference to  FIGS. 4A ,  4 B,  4 C,  5 A, and  5 B.  FIG. 4A  shows the head maintaining apparatus  100  in a state thereof before the nozzle surface  31   a  of the head  30  is air-tightly sealed;  FIG. 43  shows a sealing member  50 ; and  FIG. 4C  shows the protector  21 .  FIG. 5A  shows the head maintaining apparatus  100  in a state thereof after the nozzle surface  31   a  of the head  30  is sealed; and  FIG. 5B  shows engaging portions  60   h ,  70   c  of an upper case  70  and a lower case  60  of the apparatus  100 . 
   The head maintaining apparatus  100  includes the sealing member  50  that air-tightly seals the nozzle surface  31   a ; the lower case  60  that holds the sealing member  50 ; the upper case  70  that cooperates with the lower case  60  to hold or accommodate the head holder  9  holding the inkjet head  30 ; and a sealing plug  80  that air-tightly closes a communication hole  50   c  of the sealing member  50 . 
   The sealing member  50  is formed of an elastic material such as a rubber, and includes a plate-like base portion  50   a  and an annular lip portion  50   b  projecting from an upper surface of the base portion  50   a . The lip portion  50   b  can air-tightly contact and cover the nozzle surface  31   a  such that the lip portion  50   b  surrounds all the nozzles  35 ,  36 ,  37 ,  38  ( FIG. 3 ) and cooperates with the nozzle surface  31   a  to define an air-tightly inner space  51 . The communication hole  50   c  that communicates with each of two opposite surfaces of the sealing member  50  is formed through a thickness of a portion of the base portion  50   a  that is surrounded by the annular lip portion  50   b.    
   The sealing plug  80  includes a plate-like head portion  80   b  that can be pushed with a finger of a person, and an insertion portion  80   a  that projects from a central portion of the head portion  80   b  and can be inserted into the communication hole  50   c  of the sealing member  50 . The insertion portion  80   a  has a transverse cross section whose size is somewhat larger than that of the communication hole  50   c , and has an axial length assuring that the insertion portion  80   a  can be inserted into the communication hole  50   c  via a bottom hole  60   e  of the lower case  60 . 
   The lower case  60  has a box-like shape having an upper open end  60   a , a bottom wall  60   b , and a leg portion  60   c  that defines a prescribed space below the bottom wall  60   b.    
   A holding portion  60   d  that holds the sealing member  50  at a prescribed position is provided on an upper surface of the bottom wall  60   b , such that the holding portion  60   d  projects upward from the upper surface. The bottom hole  60   e  is formed through a thickness of a portion of the bottom wall  60   b  that corresponds to the communication hole  50   c  of the sealing member  50  in the state in which the sealing member  50  is held by the holding member  60   d , so that the inner space  51  defined by the sealing member  50  communicates with an outer space located outside the lower case  60 , i.e., the atmosphere. The lower case  60  has, in an inner space thereof, two plate-like guide members  60   f  that cooperate with each other to guide the head holder  9  to a prescribed position. In addition, the two guide members  60   f  cooperate with each other to support the head holder  9  such that the nozzle surface  31   a  keeps its horizontal posture, and position the holder  9  such that the nozzle surface  31   a  contacts the lip portion  50   b  of the sealing member  50 . 
   The upper case  70  has a box-like shape having a lower open end that allows the upper case  70  to cover externally the upper open end  60   a  of the lower case  60 . The upper case  70  has, on a lower surface of a top wall thereof, two pressing members  70   a  that project in the downward direction and that contact two portions of an upper surface of the cover member  9   d  of the head holder  9 , respectively, and press the holder  9  in the downward direction, in the state in which the upper case  70  is engaged with the lower case  60 . In the present embodiment, each of the two pressing members  70   a  has a plate-like shape. 
   Method of Maintaining Inkjet Head  30   
   Next, there will be described a method of maintaining the inkjet head  30  by using the head maintaining apparatus  100 . 
   First, the sealing member  50  whose communication hole  50   c  is kept open is held by the holding portion  60   d  of the lower case  60  and, in this state, the head holder  9  to which the protector  21  is attached is guided by the two guide members  60   f , so that the nozzle surface  31   a  of the holder  9  is held in contact with the lip portion  50   b  of the sealing member  50 . Thus, the sealing member  50  and the nozzle surface  31   a  cooperate with each other to define the inner space  51  inside the lip portion  50   b . The inner space  51  communicates with the atmosphere via the communication hole  50   c  of the sealing member  50  and the bottom hole  60   e  of the bottom wall  60   b  of the lower case  60 . 
   In this state, the tube joint  20  has not been attached to the head holder  9  yet, that is, the protector  21  remains attached to the head holder  9 . As shown in  FIG. 4C , the protector  21  has, on opposite side surfaces thereof, two elastically deformable operable portions  21   a  that are operable with fingers of a person, and two engaging portions  21   b  that are integral with respective lower end portions of the two operable portions  21   a . In a state in which the two engaging portions  21   b  of the protector  21  are engaged with a lower surface of the arm portion  9   a , the protector  21  is attached to the head holder  9  while closing the four connection ports  40   f  of the buffer tank  40 . Thus, the four color inks can be prevented from drying up through the connection ports  40   f.    
   Meanwhile, when the head holder  9  is attached to the inkjet printer  1 , the protector  21  is detached from the holder  9  by operating the two operable portions  21   a  and disengaging the two engaging portions  21   b  from the arm portion  9   a , and then the tube joint  20  is attached to the arm portion  9   a.    
   Subsequently, the upper case  70  is placed on the upper open end  60   a  of the lower case  60 , so that the pressing members  70   a  contact the upper surface of the cover member  9   d . Then, if the upper case  70  is pressed against the lower case  60 , two fixing portions  70   b  that are provided on two opposite side surfaces of the upper case  70 , as shown in FIGS.  5 A and  5 B,affix the upper and lower cases  70 ,  60  to each other, so that the nozzle surface  31   a  is pressed against the sealing member  50 . More specifically described, the upper and lower cases  70 ,  60  are fixed to each other such that respective upper surfaces of the two first engaging portions  70   c  projecting inward from respective lower ends of the two fix portions  70   b  are engaged with respective lower surfaces of the two second engaging portions  60   h  projecting outward from two side walls  60   g  of the lower case  60 . On the other hand, if two releasing portions  70   d  extending outward and upward from the respective lower ends of the two fixing portions  70   b  are pressed with fingers of a person, the two first engaging portions  70   c  are disengaged or released from the two second engaging portions  60   h , so that the upper case  70  can be disengaged or separated from the lower case  60 . 
   When the upper case  70  and the lower case  60  are engaged with each other, the sealing member  50  is pressed and the lip portion  50   b  thereof is deformed or compressed and is held in pressed contact with the nozzle surface  31   a . Thus, a volume of the inner space  51  is decreased. Since, however, the inner space  51  communicates with the atmosphere via the communication hole  50   c  and the bottom hole  60   e , an air pressure in the inner space  51  is not increased. Thus, a meniscus of the ink present in each of the nozzles  35  through  38  is not broken. 
   Then, the insertion portion  80   a  of the sealing plug  80  is inserted into the communication hole  50   c  via the bottom hole  60   e . Since the size of the insertion portion  80   a  is somewhat larger than that of the communication hole  50   c , an outer surface of the insertion portion  80   a  and an inner surface of the communication hole  50   c  are held in pressed contact with each other, owing to an elasticity of the sealing member  50 . Thus, the communication hole  50   c  is closed by the sealing member  80  such that the inner space  51  is air-tightly isolated from the atmosphere. 
   The first embodiment relates to the inkjet printer  1 . However, the principle of the present invention is applicable to other sorts of inkjet recording devices such as a facsimile machine. 
   Before the head holder  9  holding the inkjet head  30  is packaged in the head maintaining apparatus  100 , the head holder  9  is subjected to an ejecting test, in a state in which the buffer tank  40  of the head holder  9  accommodates the four color inks, or a different liquid analogous with the inks. If each of the nozzles  35  through  38  of the inkjet head  30  normally ejects a droplet of ink, it can be said that a meniscus of the ink present in the each nozzle is formed at an appropriate position. Therefore, if the head holder  9  including the inkjet head  30  in this state is packaged in the head maintaining apparatus  100  and then is attached to the inkjet printer  1 , the inkjet head  30  can normally start its ink ejecting operation in the inkjet printer  1 . 
   Advantages of First Embodiment 
   (1) In the above-described head maintaining apparatus  100  and the above-described head maintaining method, the sealing member  50  has the communication hole  50   c  that communicates, on one hand, with the inner space  61  defined between the sealing member  50  and the nozzle surface  31   a  when the sealing member  50  covers the nozzle surface  31   a , and communicates, on the other hand, with the atmosphere. Thus, when the sealing member  50  covers the nozzle surface  31   a , a certain amount of air present in the inner space  51  can be released into the atmosphere via the communication hole  50   c , and accordingly the air pressure in the inner space  51  can be prevented from being excessively increased. Therefore, the meniscus of the ink present in each of the nozzles  86  through  38  can be reliably prevented from being broken. 
   In addition, since the communication hole  50   c  can be closed with the sealing plug  80 , the inner space  51  can be air-tightly isolated from the atmosphere. Therefore, each of the nozzles  35  through  38  can be isolated from the atmosphere and the ink present in the each nozzle can be effectively prevented from being dried up. 
   (2) In the simple operation in which the inkjet head  30  is placed between the upper and lower cases  70 ,  60  and the upper case  70  is pressed against the lower case  60 , the sealing member  50  is held in pressed contact with the nozzle surface  31   a . Thus, the nozzle surface  31   a  can be air-tightly sealed with an improved efficiency. 
   In addition, since the inkjet head  30  is placed between the upper and lower cases  70 ,  60 , the head  30  can be effectively prevented from colliding with something else. That is, the recording head  30  can be effectively protected, i.e., the head  30  cannot be broken. 
   (3) The communication hole  50   c  can be air-tightly closed with the sealing plug  80 , through the bottom hole  60   e  formed in the bottom wall  60   b  of the lower case  60 . Therefore, after the inkjet head  30  is placed between the upper and lower cases  70 ,  60 , the nozzle surface  31   a  can be sealed. 
   (4) The communication hole  50   c  can be closed with the sealing plug  80 , i.e., a simple member. Thus, the head maintaining apparatus  100  can be easily used and can be produced at low cost. 
   (5) Since the sealing member  60  is an elastic member, the sealing member  50  can air-tightly contact the nozzle surface  31   a  and accordingly can reliably seal the nozzle surface  31   a . In addition, the insertion portion  80   b  of the sealing plug  80  can air-tightly contact the communication hole  50   c , owing to an elastic restoring force of the sealing member  50 . Thus, the nozzle surface  31   a  can be reliably isolated from the atmosphere. 
   (6) The sealing member  50  includes the annular lip portion  50   b  that surrounds the nozzles  35  through  38  and defines the inner space  51 . Since the sealing member  60  does not contact the nozzles  35  through  38 , the meniscus of the ink present in each of the nozzles can be effectively prevented from being contacted with, or broken by, the sealing member  50 . In addition, the nozzles  35  through  38  are not damaged. 
   (7) In the recording-head maintaining apparatus 100 , the lower and upper cases  60 ,  70  cooperate with each other to hold the sealing member  50 , and additionally holds the inkjet head  30  such that the head  30  is separable therefrom and the sealing member  50  is kept in pressed contact with the nozzle surface  31   a  of the head  30 . Thus, an extra step of covering the nozzle surface  31   a  with the sealing member  50  can be omitted, which leads to improving the operation efficiency. In addition, since the sealing member  50  is held by the two cases  60 ,  70  and is effectively prevented from being moved out of position, the nozzle surface  31   a  can be reliably sealed by the sealing member  50 . 
   Second Embodiments 
   Hereinafter, there will be described a second embodiment of the present invention by reference to  FIGS. 6A ,  6 B,  7 A,  7 B,  7 C,  7 D,  8 , and  9 . The same reference numerals as used in the first embodiment are used to designate the corresponding elements or parts of the second embodiment, and the description of those elements or parts is omitted.  FIG. 6A  shows a device for forming two through-holes in a sealing member  53 ;  FIG. 6B  shows the sealing member  63 ;  FIG. 7A  shows an upper case  70 ;  FIG. 7B  shows a protector member  21 ;  FIG. 7C  shows a head holder  9 ; FIG.  7 D shows a lower case  60  in a state in which the sealing member  53  placed in the lower case  60  are penetrated by two needle-like members  94 ;  FIG. 8  shows a recording-head maintaining apparatus  100  in a state in which the maintaining apparatus  100  holds the head holder  9  holding the inkjet head  30 ; and  FIG. 9  shows an operation table  92  and the head maintaining apparatus  100  removed from the operation table  92 . 
   Construction of Head Maintaining Apparatus 
   In the second embodiment, five arrays of nozzles  85 ,  36 ,  37 ,  38  ( FIG. 3 ) of an inkjet head  30  are grouped into two nozzle groups, i.e., a first nozzle group including the nozzles  35 ,  36  and a second nozzle group including the nozzles  37 ,  38 . As shown in  FIG. 6B , the sealing member  53  has two sections corresponding to the two nozzle groups. Thus, the device for forming the two through-holes in the sealing member  63 , shown in  FIG. 6A , includes the two needle-like members  94  and two penetration jigs  93  that correspond to the two nozzles groups, respectively. Each of the two penetration jigs  93  includes a guide portion  93   a , a pusher portion  93   b , and a stopper portion  93   c . As shown in  FIG. 6A , the sealing member  63  employed by the second embodiment has no communication holes like the communication hole  50   c  of the sealing member  60  employed in the first embodiment. More specifically described, the sealing member  53  includes a plate-like base portion  53   a  and a lip portion  53   b  projecting from an upper surface of the base portion  53   a , and has two guide holes  53   c  at respective positions near to an inner circumferential surface of an outer annular portion of the lip portion  53   b . The two guide holes  53   c  belong to the above-described two sections of the sealing member  53 , respectively, and extend from the upper surface of the base portion  53   a  toward a lower surface thereof, but do not reach the lower surface. Thus, each of the two guide holes  53   c  has a bottom. A bottom wall  60   b  of the lower case  60  has two bottom holes  60   e  at respective positions corresponding to the two guide holes  53   c  of the sealing member  53 . 
   Each of the two needle-like members  94  is a hollow member, and includes a sharp end portion  94   a  to penetrate the sealing member  53 , and a side open hole  94   b  that is located near the end portion  94   a  and communicates with a rear open end  94   c  via a communication passage, not shown, formed in the each needle-like member  94 . 
   The operation table  92  is for a person to perform an operation on the lower case  60  in a state in which the lower case  60  is held in position. More specifically described, the operation table  92  includes a positioning portion  92   a  that positions the lower case  60  at an appropriate position, and has two through-holes  92   b ,  92   b  that are formed through a thickness of the table  92  and into which the two needle-like members  94  are inserted. 
   Each of the two, penetration jigs  93  includes the guide portion  93   a  that guides the corresponding needle-like member  94  so that the needle-like member  94  may penetrate the corresponding guide hole  53   c  of the sealing member  63 ; and the bar-like pusher portion  93   b  that pushes the rear open end  94   c  of the needle-like member  94  so that the needle-like member  94  may penetrate the sealing member  53 , and the through-hole forming device further includes a base member  93   d  that supports the guide portion  93   a  above the sealing member  53 . 
   More specifically described, the guide portion  93   a  is fixed to a recessed portion  93   f  of the base portion  93   d  that has, in a bottom thereof, a through-hole  93   g . The guide portion  93   a  has a guide passage  93   e  formed therethrough in an axial direction thereof, and the guide passage  93   e  holds the corresponding needle-like member  94  in a vertical direction. The through-hole  93   g  and the guide passage  93   e  communicate with each other, and are located at a position right above the corresponding guide hole  53   c  of the sealing member  53 . 
   The base member  93   d  is guided by the two guide members  60   f  of the lower case  60 , so that a lower surface of the base member  93   d  is contacted with the sealing member  53 . 
   Each of the two penetration jigs  93  has, in an upper end portion thereof, the stopper portion  93   c  that limits an amount of movement of the pusher portion  93   b  to push the corresponding needle-like member  94  into the sealing member  53 . 
   Method of Penetrating Sealing Member  53   
   Next, a method of penetrating, using the two needle-like members  94 , will be described, the sealing member  53  so as to form two communication passages each of which communicates, at one end thereof, with a corresponding one of two inner spaces  51  corresponding to the above-described two nozzle groups, respectively, and communicates, at the other end thereof, with an atmosphere. First, the lower case  60  holding the sealing member  53  is placed on the operation table  92 , and then the two penetration jigs  93  and the base member  93   d  are placed on the upper surface of the sealing member  53 . In this state, the two through-holes  92   b  of the operation table  92  are aligned with the two guide holes  53   c  of the sealing member  53  via the two bottom holes  60   e  of the lower case  60 , respectively. 
   Subsequently, the two needle-like members  94  are inserted in the respective guide portions  53   a  of the two penetration jigs  93 , and the respective pusher portions  93   b  of the two jigs  93  are operated to push the respective rear open ends  94   c  of the two needle-like members  94  in a downward direction. 
   Then, the two needle-like members  94  are caused to penetrate the sealing member  53 , till respective lower surfaces of the two stopper portions  93   c, but on respective upper surfaces of the two guide portions  93   a . Thus, as shown in  FIG. 7D , the respective end portions  94   a  of the two needle-like members  94  penetrate the sealing member  53  via the two guide holes  53   c , and extend through the two bottom holes  60   e  of the lower case  60  and reach respective intermediate portions of the two through-holes 92   b  of the operation table  92 . In addition, the respective rear open ends  94   c  of the two needle-like members  94  are made substantially flush with the upper surface of the base portion  53   a  of the sealing member  53 . Since respective rear or base end portions of the two needle-like members  94  that penetrate the sealing member  53  are held by an elastic restoring force of the sealing member  53 , the needle-like members  94  are fixed to the sealing member  53  in a state in which the needle-like members  94  penetrate the sealing member  53 . In this state, the respective rear open ends  94   c  of the two needle-like members  94  are exposed in the two inner spaces  51 , and the respective side open holes  94   b  of the needle-like members  94  are exposed to the atmosphere outside the lower case  60 . Thus, the two inner spaces  51  and the atmosphere outside the lower case  60  communicate with each other via the two needle-like members  94 , respectively. 
   Method of Maintaining Inkjet Head  30   
   Next, there will be described a method of maintaining, using the head maintaining apparatus  100 , the inkjet head  30 . 
   First, the two penetration jigs  93  and the base member  93   d , shown in  FIG. 6A , are removed from the lower case  60 , and then the head holder  9  ( FIG. 7C ) to which the protector ( FIG. 7B ) is attached is guided by the two guide members  60   f  so that the nozzle surface  31   a  of the inkjet head  30  held by the head holder  9  is held in contact with the lip portion  53   b  of the sealing member  53 . 
   Next, the upper case ( FIG. 7A ) is attached to an upper open end portion  60   a  of the lower case  60 , in the same manner as that employed in the first embodiment, so that the head holder  90  is held, as shown in  FIG. 8 , between the lower case  60  and the upper case  70 . 
   Since the sealing member  53  is compressed, the lip portion  53   b  is elastically deformed and is held in pressed contact with the nozzle surface  31   a . Thus, the respective volumes of the two inner spaces  51  are decreased by the elastic deformation of the lip portion  53   b . Since, however, the two inner spaces  51  communicate with the outer atmosphere via the two needle-like members  94 , respectively, respective air pressures in the two inner spaces  51  are not increased. Thus, respective meniscuses of the inks present in the nozzles  35  through  38  ( FIG. 3 ) are not broken. 
   Then, as shown in  FIG. 9 , the head maintaining apparatus  100  holding the head holder  9  is removed from the operation table  92 , and the two needle-like members  94  penetrating the sealing member  53  are pulled out, using a tool such as a pair of pincers, from the sealing member  53  into an outside space. Consequently, the two through-holes formed by the penetration of the two needle-like members  94  are closed by the elastic restoring deformation of respective portions of the sealing member  53  that define the two through-holes. Thus, the two inner spaces  51  are air-tightly closed and accordingly the nozzle surface  31   a  is air-tightly sealed. 
   Advantages of Second Embodiment 
   (1) In the above-described head maintaining apparatus  100  and the above-described head maintaining method, the inner spaces  51  formed between the sealing member  63  and the nozzle surface  31   a  when the sealing member  53  covers the nozzle surface  31   a , are communicated with the atmosphere via the needle-like members  94  penetrating the sealing member  63 , when the sealing member  53  is closely contacted with the nozzle surface  31   a . Thus, the air present in the inner spaces  51  is discharged into the atmosphere via the needle-like members  94 , and accordingly the inner pressure in the spaces  51  is prevented from being increased. Therefore, the respective meniscuses of the inks present in the nozzles  35  through  38  are not broken. 
   In addition, after the sealing member  53  is closely contacted with the nozzle surface  31   a , the air communication between the two inner spaces  51  and the atmosphere is shut off. Therefore, the nozzles  35  through  38  are kept in an air-tight condition and accordingly the inks present in the nozzles are prevented from being dried up. 
   (2) The sealing member  53  formed of the elastic material is penetrated by the hollow, needle-like members  94 , so that the inner spaces  51  formed between the sealing member  53  and the nozzle surface  31   a  are communicated with the atmosphere via the needle-like members  94 . In addition, when the needle-like members  94  are pulled out of the sealing member  53 , the through-holes formed by the penetration of the needle-like members  94  through the sealing member  53  are closed by the elastic restoring deformation of the sealing member  53  itself Thus, the nozzle surface  30   a  can be reliably sealed without using any exclusive members, like the sealing plug  80 , for closing those through-holes. 
   In addition, since the through-holes formed in the sealing member  53  are automatically closed by the elasticity of the sealing member  53 , the through-holes can be reliably closed. 
   (3) In the simple operation in which the inkjet head  30  is placed between the upper and lower cases  70 ,  60  and the upper case  70  is attached to the lower case  60 , the sealing member  53  is held in pressed contact with the nozzle surface  31   a . Thus, the nozzle surface  31   a  can be air-tightly sealed with an improved efficiency. 
   In addition, since the inkjet head  30  is held by, and between, the upper and lower cases  70 ,  60 , the head  30  can be effectively prevented from colliding with other members. Thus, the inkjet head  30  can be effectively protected and accordingly it cannot be broken. 
   Third Embodiment 
   Hereinafter, there will be described a third embodiment of the present invention by reference to  FIGS. 10 ,  11 A,  11 B,  11 C, and  11 D. The same reference numerals as used in the first and second embodiments are used to designate the corresponding elements or parts of the third embodiment, and the description of those elements or parts is omitted.  FIG. 10  shows a device for penetrating, with two needle-like members  96 , a sealing member  63  from a lower surface thereof  FIG. 11A  shows an upper case  70 ;  FIG. 11B  shows a protector member  21 ;  FIG. 7C  shows a head holder  9 ; and  FIG. 7D  shows a lower case  60  in a state in which the sealing member  53  placed in the lower case  60  are penetrated by the two needle-like members  96 . 
   Construction of Device for Penetrating Sealing 
   Member  53  with Needle-like Members  96   
   As shown in  FIG. 10 , this penetration device includes a penetration table  95  having, on an upper surface thereof, a positioning portion  95   a  that positions the lower case  60  at an appropriate position. The penetration table  95  has two through-holes  95   b ,  95   b  that are formed through a thickness of the table  95  and into which the two needle-like members  96  are fixedly inserted such that respective upper end portions  96   a  of the two needle-like members  96  project upward from the two through-holes  95   b ,  95   b , respectively. The two through-holes  95   b ,  95   b  are formed at respective positions assuring that when the lower case  60  is placed on the penetration table  95 , the respective upper end portions  96   a  of the two needle-like members  96  that project upward from the two through-holes  95   b ,  95   b , can penetrate two guide holes  53   c  of the sealing member  53  via two bottom holes  60   e  of a bottom wall  60   b  of the lower case  60 . 
   Each of the two needle-like members  96  includes a sharp end portion  96   a  to penetrate the sealing member  53 , and a side open hole  96   b  that is located near the end portion  96   a  and communicates with a rear open end  96   c  via a communication passage, not shown, formed in the each needle-like member  96 . 
   The penetration device additionally includes a pushing jig  97  having a shape similar to that of the head holder  9 ( FIG. 9 ). The pushing jig  97  has, in a lower end thereof, a pushing portion  97   a  that pushes an outer peripheral portion of the upper surface of the sealing member  53  that is located outside the lip portion  53   b , and additionally has, in an upper end thereof, an engaging portion  97   b  that covers an upper open end  60   a  of the lower case  60  and extends outward from the upper open end  60   a.    
   Method of Penetrating Sealing Member  53   
   Next, there will be descried a method of penetrating, using the two needle-like members  96  fixed to the penetration table  95 , the sealing member  53  so as to form two communication passages each of which communicates, at one end thereof, with a corresponding one of two inner spaces  51  corresponding to the above-described two nozzle groups, respectively, and communicates, at the other end thereof, with the atmosphere. First, the pushing jig  97  is attached to the lower case  60  through the upper open end  60   a  thereof. The pushing jig  97  is guided by two guide members  60   f  of the lower case  60 , so that the pushing portion  97   a  is held in contact with the upper surface of the sealing member  53 . In this state, the engaging portion  97   b  of the pushing jig  97  is engaged with the upper open end  60   a  of the lower case  60 . Thus, when an upper surface of the pushing jig  97  is pushed by a person, the lower case  60  is pressed against the penetration table  95  while the sealing member  53  is prevented from being moved relative to the lower case  60 . 
   Subsequently, the pushing jig  97  is pushed downward against the lower case  60 , so that the lower case  60  is pushed against the penetration table  95 . Thus, the two needle-like members  96  are caused to pass through the two bottom holes  60   e  of the lower case  60 , respectively, and the respective upper end portions  96   a  of the two needle-like members  96  penetrate the two guide holes  53   c  of the sealing member  53 , respectively, from the lower surface of the sealing member  53 . When a leg portion  60   c  of the lower case  60  is contacted with the upper surface of the penetration table  92  and the pushing of the lower case  60  is finished, the respective side open holes  96   b  of the two needle-like members  96  are exposed in the two guide holes  53   c  of the sealing member  53 , without projecting upward beyond the upper surface of the plate-like base portion  53   a  of the sealing member  53 . Thus, the two inner spaces  51  are communicated with the atmosphere under the penetration table  95 . 
   Method of Maintaining Inkjet Head  30   
   Next, there will be described a method of maintaining, using the head maintaining apparatus  100 , the inkjet head  30 . 
   First, the pushing jig  97 , shown in  FIG. 10 , is removed from the lower case  60 , and then the head holder  9  ( FIG. 11C ) to which the protector ( FIG. 11B ) is attached is guided by the guide members  60   f  so that the nozzle surface  31   a  of the inkjet head  30  held by the head holder  9  is held in contact with the lip portion  53   b  of the sealing member  53 . 
   Next, the upper case ( FIG. 11A ) is attached to the upper open end portion  60   a  of the lower case  60 , in the same manner as that employed in the second embodiment, so that the head holder  9  is held between the lower case  60  and the upper case  70 . 
   Since the sealing member  53  is compressed, the lip portion  53   b  is elastically deformed and is held in pressed contact with the nozzle surface  31 a. Thus, the respective volumes of the two inner spaces  51  are decreased by the elastic deformation of the lip portion  63   b . Since, however, the two inner spaces  51  communicate with the atmosphere via the two needle-like members  96 , respectively, respective air pressures in the two inner spaces  51  are not increased. Thus, respective meniscuses of the inks present in the nozzles  36  through  38  ( FIG. 3 ) are not broken. 
   Then, the head maintaining apparatus  100  holding the head holder  9  is removed from the penetration table  95 , so that the two needle-like members  96  penetrating the sealing member  53  are pulled out of the sealing member  53 . Consequently, the two through-holes formed by the penetration of the two needle-like members  96  are closed by the elastic restoring deformation of respective portions of the sealing member  53  that define the two through-holes. Thus, the two inner spaces  51  are air-tightly closed and accordingly the nozzle surface  31   a  is air-tightly sealed. 
   Advantages of Third Embodiment 
   (1) In the above-described head maintaining apparatus  100  and the above-described head maintaining method, the two inner spaces  51  formed between the sealing member  53  and the nozzle surface  31   a  when the sealing member  53  covers the nozzle surface  31   a , are communicated with the atmosphere via the needle-like members  96  penetrating the sealing member  53 , when the sealing member  53  is air-tightly contacted with the nozzle surface  31   a . Thus, the air present in the inner spaces  61  is discharged into the atmosphere via the needle-like members  96 , and accordingly the inner pressure in the spaces  51  is prevented from being increased. Therefore, the respective meniscuses of the inks present in the nozzles  35  through  38  are not broken. 
   In addition, after the sealing member  53  is closely contacted with the nozzle surface  31   a , the air communication between the two inner spaces  51  and the atmosphere is shut off. Therefore, the nozzles  35  through  38  are kept in an air-tight condition and accordingly the inks present in the nozzles are prevented from being dried up. 
   (2) The sealing member  53  formed of the elastic material is penetrated by the hollow, needle-like members  96 , so that the inner spaces  51  formed between the sealing member  53  and the nozzle surface  31   a  are communicated with the atmosphere via the needle-like members  96 . In addition, when the needle-like members  96  are pulled out of the sealing member  53 , the through-holes formed by the penetration of the needle-like members  96  through the sealing member  53  are closed by the elastic restoring deformation of the sealing member  53  itself. Thus, the nozzle surface  30   a  can be reliably sealed without using any exclusive members,. like the sealing plug  80 , for closing those through-holes. 
   In addition, since the through-holes formed in the sealing member  53  are automatically closed by the elasticity of the sealing member  53 , those through-holes can be reliably closed. 
   Moreover, since the needle-like members  96  are fixed to the penetration table  95 , the needle-like members  96  can be pulled out of the sealing member  53 , by removing the head maintaining apparatus  100  from the penetration table  95 . Thus, a step of pulling the needle-like members  96  only from the sealing member  63  is not needed, which leads to improving an operation efficiency. 
   (3) In the simple operation in which the inkjet head  30  is placed between the upper and lower cases  70 ,  60  and the upper case  70  is attached to the lower case  60 , the sealing member  53  is held in pressed contact with the nozzle surface  31   a . Thus, the nozzle surface  31   a  can be air-tightly sealed with an improved efficiency. 
   In addition, since the inkjet head  30  is held by, and between, the upper and lower cases  70 ,  60 , the head  30  can be effectively prevented from colliding with other members, Thus, the inkjet head  30  can be effectively protected and accordingly it cannot be broken. 
   Other Embodiments 
   (1) The sealing plug  80  employed in the first embodiment may be replaced with a sealing plug that is integral with a lower case  60 , as shown in  FIG. 12 . In a fourth embodiment shown in  FIG. 12 , a sealing plug  62  is formed as an integral portion of the lower case  60 . The sealing plug  62  includes an arm portion  62   a  that extends downward from an edge of a bottom hole  60   e  of the lower case  60 , and an insertion portion  62   b  that projects from an end portion of the arm portion  62   a  and can be inserted in a communication hole  60   c  of a sealing member  50 . The arm portion  62   a  has an appropriate degree of flexibility, and accordingly allows a person to insert the insertion portion  62   b  into the communication hole  50   c , so that the insertion portion  62   b  is fixed by an elasticity of the sealing member  50 . Thus, a space  51  defined by, and between, the sealing member  50  and a nozzle surface  31   a  can be air-tightly sealed. In this embodiment, the insertion portion  62   b  is integral with the lower case  60  and accordingly it is prevented from being lost. In addition, the present head maintaining apparatus can enjoy the same advantages as those of the head maintaining apparatus  100  as the first embodiment. 
   (2) The sealing plug  80  employed in the first embodiment may be replaced with a sealing plug that is integral with a sealing member  50 , as shown in  FIG. 13 . In a fifth embodiment shown in  FIG. 13 , a sealing plug  52  is formed as an integral portion of the sealing member  50 . The sealing plug  62  includes an arm portion  62   a  that extends downward from one end of a lower surface of the sealing member  60 , and an insertion portion  52   b  that projects from an end portion of the arm portion  52   a  and can be inserted in a communication hole  50   c  of the sealing member  50 . The arm portion  52   a  has an appropriate degree of flexibility, and accordingly allows a person to insert the insertion portion  52   b  into the communication hole  50   c , so that the insertion portion  52   b  is fixed by an elasticity of the sealing member  50 . Thus, a space  51  defined by, and between, the sealing member  50  and a nozzle surface  31   a  can be air-tightly sealed. In this embodiment, the insertion portion  52   b  is integral with the sealing member  50  and accordingly it is prevented from being lost. In addition, the present head maintaining apparatus can enjoy the same advantages as those of the head maintaining apparatus  100  as the first embodiment. 
   (3) The sealing plug  80 ,  62 ,  52  as a closing member that closes the communication hole  50   c  of the sealing member  50  may be replaced by a packing material  71  such as an adhesive or a putty, as shown in  FIG. 14 . The packing material  71  is injected to the communication hole  50   c , by an injecting member  72  such as a syringe. Since the communication hole  50   c  is air-tightly closed by the packing material  71 , the present arrangement is free from a problem that the closing member such as the sealing plug  80 ,  62 ,  52  may come off the sealing member  60 . Thus, the communication hole  50   c  can be closed with reliability. This embodiment can also enjoy the same advantages as those of the head maintaining apparatus  100  as the first embodiment. 
   (4) The sealing member  50 ,  58  may be pressed against the nozzle surface  31   a  of the inkjet head  30 , by fixing the head holder  9  and the lower case  60  to each other. For example, an outer surface of the head holder  9  and an upper end of the lower case  60  are provided with respective hooks, and the head holder  9  and the lower case  60  are fixed to each other, by causing those hooks to be engaged with each other, such that the nozzle surface  31   a  of the head holder  9  is pressed against the sealing member  50 ,  53 . This embodiment can also enjoy the same advantages as those of the head maintaining apparatus  100  as each of the first to third embodiments. 
   In each of the illustrated embodiments, the recording sheet P corresponds to a recording medium; the inkjet head  30  corresponds to a recording head; the inkjet printer  1  corresponds to a recording device; a portion of the inkjet printer  1  that excludes the head holder  9  corresponds to a remaining portion of the recording device; and the sealing plug  80 ,  62 ,  52 , the elasticity of the sealing member  53 , or the packing material  71  corresponds to air-tightly closing means. 
   In addition, at least one of the lower case  60  and the upper case  70  corresponds to at least one holding member; the bottom hole  60   e  corresponds to an opening; and the bottom wall  60   b  corresponds to the wall that covers one of two opposite surfaces of the sealing member  50 ,  53  that is opposite to the other opposite surface thereof that is opposed to the nozzle surface  31   a  of the inkjet head  30  as the recording head. 
   The sealing plug  80  (or the insertion portion  80   a  thereof), the sealing plug  52  (or the insertion portion  52   b  thereof), or the sealing plug  62  (or the insertion portion  62   b  thereof) corresponds to a plug. 
   At least one of the needle-like members  94 ,  96  corresponds to at least one tubular member. 
   It is to be understood that the present invention may be embodied with other changes and improvements that may occur to a person skilled in the art, without departing from the spirit and scope of the invention defined in the claims.