Abstract:
A waste ink storage structure including: container walls, defining a storage space adapted to store a waste ink; a waste ink inlet portion adapted to pour the waste ink into the storage space; a vent communicating the storage space with atmosphere; and a valve, provided at the vent to be opened when the waste ink is poured from the waste ink inlet portion.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Technical Field of the Invention  
         [0002]     The present invention relates to a waste ink storage structure that stores waste ink to be generated by a head cleaning operation and so on, and to an ink cartridge, a waste ink tank and an ink jet printer having the same.  
         [0003]     2. Description of the Related Art  
         [0004]     In an ink jet printer, during a head cleaning operation to be performed in order to prevent degradation of print quality due to clogging of ink or during an ink filling operation after replacement of an ink cartridge, waste ink is generated. Accordingly, a waste ink storage structure that collects generated waste ink so as to prevent waste ink from being unexpectedly attached to mechanisms in the printer is required.  
         [0005]     In the waste ink storage structure, in general, a storage space for storing waste ink is defined by container walls, and a waste ink inlet portion that pours waste ink into the storage space is provided at a portion of one of the container walls. Further, a vent connects the waste ink storage space to the outside at a position spaced from the waste ink inlet portion on the container wall so as to expose the waste ink storage space to the atmosphere. In addition, an ink absorption member that absorbs waste ink poured by the waste ink inlet portion is provided in the waste ink storage space. The waste ink storage structure may be incorporated into a case of the ink cartridge (for example, see JP-A-11-70672) or may be separately incorporated into a portion of a printer housing of an ink jet printer (for example, see JP-A-8-318629).  
         [0006]     In the above-described waste ink storage structure, the vent that exposes the storage space to the atmosphere releases air in the storage space to the outside so as to prevent a pressure in the storage space from increasing due to the pouring of waste ink.  
         [0007]     In the related waste ink storage structure, the vent is constantly exposed to the outside, and thus moisture of waste ink absorbed by the ink absorption member is always transpired from the vent to the outside.  
         [0008]     As a result, in particular, when pigment-based ink is used, hardening of waste ink may easily occur, and hardened ink may degrade absorption capability of the ink absorption member. Accordingly, it may be impossible to fully utilize the original absorption capacity of the ink absorption member, and to stably use the ink absorption member for a long time. Further, a pressure in a waste ink supplying side tube connected to the waste ink inlet portion and so on may be abnormally increased due to clogging caused by hardened waste ink. Then, the tube may be removed due to the abnormal increase in pressure, which causes ink leakage.  
       SUMMARY OF THE INVENTION  
       [0009]     Accordingly, the invention has been finalized in order to solve at least one of the above-described problems, and it is an object of at least one embodiment of the invention to provide a waste ink storage structure which can collect waste ink for a long time, and an ink cartridge, a waste ink tank and an ink jet printer having such a waste ink storage structure.  
         [0010]     According to an aspect of at least one embodiment of the invention, a waste ink storage structure comprising: container walls, defining a storage space adapted to store a waste ink, and provided with a waste ink inlet portion adapted to pour the waste ink into the storage space and a vent communicating the storage space with atmosphere; a valve, provided at the vent to be opened when the waste ink is poured from the waste ink inlet portion.  
         [0011]     According to the waste ink storage structure having this configuration, the vent that communicates the storage space to the atmosphere is kept in a closed state by the valve, excluding when waste ink is poured from the waste ink inlet portion.  
         [0012]     Therefore, moisture of waste ink poured into the storage space is suppressed from being transpired from the vent to the outside, and thus it is possible to prevent hardening of waste ink in the storage space.  
         [0013]     In the waste ink storage structure having the above-described configuration, the waste ink storage structure may further comprise an ink absorption member, provided in the storage space and adapted to absorb the waste ink.  
         [0014]     According to the waste ink storage structure having the above-described configuration, the absorption capability of the ink absorption member is prevented from being degraded due to hardening of waste ink.  
         [0015]     In the waste ink storage structure having the above-described configuration, the container walls may include a flexible container wall formed of a flexible sheet member provided with the vent, and the valve may have: the flexible container wall; and a valve structure member having a contact portion which comes into contact with a perimeter of the vent to block the vent, and be constructed such that the vent is opened when the perimeter of the vent displaces and separates from the contact portion by a pouring pressure of the waste ink poured from the waste ink inlet portion.  
         [0016]     According to the waste ink storage structure having this configuration, the valve for opening/closing the vent can be obtained only by forming the vent to pass through the flexible sheet member constituting the container wall and integrally forming a support or a rib serving as the valve structure member in another container wall facing the vent. The vent perimeter of the valve is separated from the contact portion of the valve structure member by an expansion operation of the flexible sheet member due to the pouring pressure of waste ink from the waste ink inlet portion.  
         [0017]     Therefore, parts for providing the valve do not need to be added, and thus costs can be prevented from being increased due to an increase in the number of parts or an increase in the number of assembling steps.  
         [0018]     At the time of discarding the ink absorption member, one surface of the storage surface can be largely opened by removing the flexible sheet member, such as a plastic film or the like, having the vent from other container walls. Then, the ink absorption member having absorbed waste ink can be simply removed from the storage space.  
         [0019]     The ink absorption member may be spaced away from the periphery of the contact portion of the valve structure member.  
         [0020]     According to this configuration, since the contact portion and the ink absorption member are spaced apart from each other, a capillary force does not exert between them, and thus ink absorbed by the ink absorption member does not exude to the contact portion. Therefore, there is no case where waste ink flows out from the vent.  
         [0021]     The vent may be disposed on a central line of short side in the flexible container wall. In this case, displacement becomes the maximum, and thus an operation pressure as a valve can be reduced. Further, since displacement at the vent of the flexible container wall is balanced on the sides thereof, the vent perimeter can be uniformly brought into contact with the contact portion.  
         [0022]     In the waste ink storage structure according to this configuration, the contact portion of the valve structure member may be provided with a protrusion passing through the vent of the flexible sheet member.  
         [0023]     According to this configuration, positioning of the contact portion of the valve structure member and the vent of the flexible sheet member is easily performed at the time of assembly, and thus assembly workability can be improved.  
         [0024]     A valve body of the valve to block the vent may be integrally formed with an elastic member having an open-close portion elastically displacable in an opening direction by a pouring pressure of the waste ink poured from the waste ink inlet portion  
         [0025]     According to this configuration, an exclusive-use valve body constituting the valve needs to be provided. However, by suitably setting elasticity in the open/close portion of the valve body, sealing capability of the vent by the valve can be improved, and also the capability to prevent transpiration of moisture from the vent can be improved. Further, the container wall having the vent provided therein is not limited to the flexible sheet member, such as a plastic film or the like. Therefore, a degree of freedom for design of an ink cartridge or a printer housing having the waste ink storage structure can be improved.  
         [0026]     According to another aspect of at least one embodiment of the invention, an ink cartridge includes the waste ink storage structure having the above-described configuration and an ink pack adapted to store ink therein.  
         [0027]     According to the ink cartridge having this configuration, moisture of waste ink poured into the storage space is suppressed from being transpired from the vent to the outside. Therefore, it is possible to obtain an ink cartridge that can prevent hardening of waste ink in the storage space and can prevent absorption capability of the ink absorption member from being degraded due to hardening of waste ink.  
         [0028]     In the ink cartridge having the above-described configuration, the container walls may include a flexible container wall formed of a flexible sheet member provided with the vent, and the flexible container wall defines an accommodating space accommodating the ink pack and the storage space.  
         [0029]     According to this configuration, the vent is not directly exposed the outside of the ink cartridge, but communicates with the atmosphere through the accommodating space for accommodating the ink packs. Therefore, the situation in which a user unexpectedly touches the valve provided at the vent, which causes a trouble in valve functions, can be prevented.  
         [0030]     In the ink cartridge having the above-described configuration, the vent may be provided at a position that does not interfere with the ink pack.  
         [0031]     According to this configuration, the ink packs accommodated in the accommodating space of the ink cartridge do not interfere with the valve functions of the valve provided at the vent.  
         [0032]     When ink is pigment-based ink, hardening prevention effects of waste ink in the storage space can be markedly achieved.  
         [0033]     According to still another aspect of at least one embodiment of the invention, an ink jet printer includes the ink cartridge having the above-described configuration.  
         [0034]     According to the ink jet printer having this configuration, moisture of waste ink poured into the storage space is suppressed from being transpired from the vent to the outside. Therefore, it is possible to obtain an ink jet printer that can prevent the hardening of waste ink in the storage space and can prevent absorption capability of the ink absorption member from being degraded due to hardening of waste ink.  
         [0035]     According to a further aspect of at least one embodiment of the invention, a waste ink tank includes the waste ink storage structure having the above-described configuration.  
         [0036]     According to the waste ink tank having this configuration, moisture of waste ink poured into the storage space is suppressed from being transpired from the vent to the outside. Therefore, it is possible to obtain a waste ink tank that can prevent hardening of waste ink in the storage space and can prevent the absorption capability of the ink absorption member from being degraded due to hardening of waste ink.  
         [0037]     The waste ink tank may be detachably mounted in a tank accommodating portion of a printer housing.  
         [0038]     According to this configuration, only the waste ink tank can be independently removed from the printer housing. Therefore, only the waste ink tank that is stained with ink can be separately managed, and the non-stained printer housing can be recycled or reused as it is. In addition, since the waste ink tank is detachably provided, in a certain situation, a worker can replace only the waste ink tank with a new one without staining his/her hands.  
         [0039]     According to the waste ink storage structure, and the ink cartridge, the waste ink tank and the ink jet printer having the waste ink storage structure of the invention, the vent communicating the storage space for storing waste ink with the atmosphere is kept in a closed state by the valve excluding when waste ink is poured from the waste ink inlet portion.  
         [0040]     Therefore, moisture of waste ink poured into the storage space is suppressed from being transpired from the vent to the outside. Therefore, it is possible to prevent hardening of waste ink in the storage space, and in case where the absorption member is provided in the waste ink storage structure, also to prevent the absorption capability of the ink absorption member from being degraded due to hardening of waste ink.  
         [0041]     As a result, original absorption capability of the ink absorption member can be fully utilized, and the ink absorption member can be stably used to collect waste ink for a long time. Further, since clogging due to hardened waste ink does not occur, the situation in which a pressure in a waste ink supplying side tube connected to the waste ink inlet portion is abnormally increased is prevented. Therefore, the occurrence of an inconsistency, such as light leakage or the like, due to the removal of the tube or the like can be prevented. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0042]      FIG. 1  is an exterior perspective view showing the overall configuration of an ink jet printer on which an ink cartridge having a waste ink storage structure according to an embodiment of the invention is mounted;  
         [0043]      FIG. 2  is an overall perspective view of the ink cartridge shown in  FIG. 1 ;  
         [0044]      FIG. 3  is an exploded perspective view of the ink cartridge shown in  FIG. 2 ;  
         [0045]      FIG. 4  is a longitudinal cross-sectional view of the ink cartridge shown in  FIG. 2 ;  
         [0046]      FIG. 5  is an expanded cross-sectional view showing essential parts of the ink cartridge shown in  FIG. 2 ;  
         [0047]      FIGS. 6A  to  6 C are cross-sectional views illustrating opening and closing operations of a valve shown in  FIG. 4 , in which  FIG. 6A  is a cross-sectional view showing a state where the valve is closed,  FIG. 6B  is a cross-sectional view showing a state where the valve is opened due to an increase in pressure within a storage space by the pouring of waste ink, and  FIG. 6C  is a cross-sectional view showing a state where the pouring of waste ink ends and the valve is closed again;  
         [0048]      FIG. 7  is an exploded perspective view schematically showing the overall configuration of an ink jet printer on which a waste ink tank having the waste ink storage structure according to an embodiment of the invention is mounted;  
         [0049]      FIG. 8  is an exploded perspective view of the waste ink tank shown in  FIG. 7 ;  
         [0050]      FIG. 9  is an expanded cross-sectional view of a valve shown in  FIG. 8 ; and  
         [0051]      FIG. 10  is a longitudinal cross-sectional view showing another configuration example of a valve according to the invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0052]     Hereinafter, a waste ink storage structure according to a first embodiment of the invention will be described in detail with reference to the accompanying drawings.  
         [0053]      FIG. 1  is an exterior perspective view showing the overall configuration of an ink jet printer on which an ink cartridge having a waste ink storage structure according to the embodiment of the invention is mounted. FIGS.  2  to  4  are an overall perspective view, an exploded perspective view, and a longitudinal cross-sectional view of the ink cartridge shown in  FIG. 1 , respectively.  FIGS. 5 and 6 A to  6 C are expanded cross-sectional views showing essential parts of the ink cartridge shown in  FIG. 2 .  
         [0054]     An ink jet printer  1  according to this embodiment performs color printing on a roll paper using a plurality of color ink liquids. As shown in  FIG. 1 , a printer cover  4  having a roll paper cover  5  and an ink cartridge cover  7  integrally formed is openably provided on a front surface of a printer case  2 . In addition, a power supply switch  3  and feed switches or indicators are disposed on the front surface of the printer case  2 .  
         [0055]     As shown in  FIG. 1 , if the printer cover  4  is opened, the roll paper cover  5  that covers a paper accommodating portion  8  for accommodating the roll paper  6  as a printing paper is opened, such that the papers can be replaced. At the same time, the ink cartridge cover  7  that covers a cartridge mounting portion  9  is also opened, such that an ink cartridge  10  can be attached and detached to and from the cartridge mounting portion  9 .  
         [0056]     In case of the ink jet printer  1  of this embodiment, the ink cartridge  10  is drawn out by a predetermine distance in front of the cartridge mounting portion  9  in connection with an opening operation of the printer cover  4 .  
         [0057]     As shown in FIGS.  2  to  4 , the ink cartridge  10  of this embodiment is mounted on the cartridge mounting portion  9  of the ink jet printer  1 . Accordingly, a waste ink storage structure  17  that stores waste ink generated at the time of an ink filling operation or a head cleaning operation of the printer is provided in a cartridge case  15  that accommodates three ink packs  11  to  13 .  
         [0058]     The three ink packs  11  to  13  are filled with ink of difference colors for color printing. The ink packs  11  to  13  have the same structure. Each of the ink packs  11  to  13  has a flexible pouch body  21  that contains ink, and an ink outlet port  23  that is bonded to a front end of the pouch body  21 .  
         [0059]     The pouch body  21  is formed by superimposing two aluminum-laminated films and bonding their peripheries to each other using a heat welding method or the like. The aluminum-laminated film is used to improve gas barrier characteristics. As the aluminum-laminated film, for example, a laminated film obtained by laminating a nylon film and a polyethylene film on both surfaces of an aluminum foil is used.  
         [0060]     The ink outlet port  23  has a cylindrical body  23   a  that is formed to have an outer diameter larger than the diameter of its front end and is fixed within the pouch body  21 , a valve body  23   b  that is mounted within the cylindrical body  23   a  so as to open/close a flow passage of the cylindrical body  23   a , and a seal film  23   c  that is attached to the front end of the cylindrical body  23   a  so as to seal an opening of the cylindrical body  23   a , as shown in  FIG. 4 . The cylindrical body  23   a  of the ink outlet port  23  is formed of, for example, hard plastic. Further, the seal film  23   c  is formed of a polyethylene film.  
         [0061]     The cylindrical body  23   a  is fixed to the aluminum-laminated film of the pouch body  21  by heat welding or the like, such that the ink outlet port  23  is integrated with the pouch body  21 .  
         [0062]     As shown in  FIGS. 3 and 4 , the cartridge case  15  has an upper case  31 , a lower caser  33  that is connected to the bottom of the upper case  31 , and an intermediate container wall  35  that vertically divides a space defined by the upper case  31  and the lower case  33 .  
         [0063]     The upper case  31  and the lower case  33  are mold products formed of suitable plastic materials. The intermediate container wall  35  is formed of a plastic film serving as a flexible sheet member. In this embodiment, a plastic film having sufficient flexibility so as to be expanded upwardly by a pouring pressure of waste ink from a waste ink inlet portion  37  is selected.  
         [0064]     The upper case  31  is in a box shape having a bottom opened and a front container wall  31   a  thereof is set to be lower than side container walls and a rear container wall. Then, semicircular cylindrical ink pack positioning portions  31   b  are formed below the front container wall  31   a  so as to position upper halves of the ink outlet ports  23  of the individual ink packs  11  to  13 . Three semicircular cylindrical ink pack positioning portions  31   b  are formed to correspond to the three ink packs  11  to  13  to be accommodated.  
         [0065]     An anchoring protrusion  31   f  of the upper case  31  is engaged with an anchoring opening  33   j  provided in a cover portion  33   d , and anchoring protrusions  31   d  provided on both sides of the upper case  31  are anchored to stepped engagement portions (not shown) provided within anchoring slits  33   a  of the lower case  33 , such that the upper case  31  and the lower case  33  are connected to each other.  
         [0066]     The lower case  33  is in a thin pan and box shape having an open top. A front container wall  33   b  is set to be higher than side container walls and a rear container wall. Semicircular cylindrical ink pack positioning portions  33   c  are formed at an upper end of the front container wall  33   b  so as to position lower halves of the ink outlet ports  23  of the individual ink packs  11  to  13 .  
         [0067]     As shown in  FIG. 3 , the semicircular cylindrical ink pack positioning portions  33   c  position and fix the ink outlet ports  23  of the individual ink packs  11  to  13 , together with the semicircular cylindrical ink pack positioning portions  31   b , by clamping the individual ink outlet ports  23  from the above and below. Like the above-described ink pack positioning portions  31   b , three semicircular cylindrical ink pack positioning portions  33   c  are formed to correspond to the three ink packs  11  to  13  to be accommodated.  
         [0068]     The cover portion  33   d  is formed at an upper end of the front container wall  33   b  to extend from the front ends of the ink pack positioning portions  33   c  so as to cover the fronts of the ink outlet ports  23 . As shown in  FIG. 4 , openings  33   e  are formed in the cover portion  33   d  to pass through the cover portion  33   d . Then, ink supply needles  41  provided in the cartridge mounting portion  9  of the ink jet printer  1  are inserted into the openings  33   e.    
         [0069]     Three openings  33   e  are formed to be correspondingly concentric with the three semicircular cylindrical ink pack positioning portions  33   c.    
         [0070]     A waste ink inlet  44  is formed at a position in a lower portion of the container wall  33   b  to constitute the waste ink inlet portion  37  in the waste ink storage structure  17 .  
         [0071]     As shown in  FIGS. 3 and 4 , the waste ink inlet portion  37  has a tapered tube-shaped rubber mouth member  37   a  having a wider inner diameter at its front end, a seal film  37   b  that is heat-welded to the front container wall  33   b  so as to prevent separation of the rubber mouth member  37   a , a valve body  37   c  that comes into contact with a rear end of the rubber mouth member  37   a  so as to close an opening of the rubber mouth member  37   a , and a compressed coil spring  37   d  that biases the valve body  37   c  in a direction to be brought into contact with the rubber mouth member  37   a.    
         [0072]     The rubber mouth member  37   a  is press-fitted into the waste ink inlet  44  in a state where the compressed coil spring  37   d  is slightly compressed. As shown in  FIG. 4 , in a state where a waste ink pouring needle  47  is not inserted, the rubber mouth member  37   a  and the valve body  37   c  are kept airtight.  
         [0073]     As shown in  FIG. 4 , the waste ink storage structure  17  of this embodiment has a storage space  51  that is defined by the lower case  33  and the intermediate container wall  35  and stores waste ink, the waste ink inlet portion  37  that pours waste ink into the storage space  51 , a vent  61  that connects the storage space  51  to the outside, two ink absorption members  63  that are provided within the storage space  51  so as to absorb waste ink poured into the storage space  51  from the waste ink inlet portion  37 , and a valve  65  that opens/closes the vent  61 . The ink absorption members  63  are molded in a rectangular shape using liquid absorbent materials so as to be accommodated within the storage space  51 . As a specific material, in addition to a porous material, such as sponge or nonwoven fabric, an absorbent polymer can be used.  
         [0074]     After the two ink absorption members  63  are set on the lower case  33 , the intermediate container wall  35  that can be formed of a plastic film (flexible sheet member), such as a polyethylene film or the like, is set such that its circumferential portion is superimposed on the upper end surfaces of the side container wall  33   f  and the front and rear container walls  33   g  and  33   h  of the lower case  33 . Then, the superimposed portions are bonded using a heat welding method or the like, such that the ink absorption members  63  are fixed to the lower case  33  while being slightly tensioned.  
         [0075]     The intermediate container wall  35  is fixed to the lower case  33  so as to cover an upper opening of the lower case  33 . Then, as shown in  FIG. 4 , the storage space  51  constituting the waste ink storage structure  17  is defined between a bottom wall  33   i  of the lower case  33  and the intermediate container wall  35 . In addition, an ink pack accommodating space  55  that accommodates the three ink packs  11  to  13  upright is defined between a top wall  31   e  of the upper case  31  and the intermediate container wall  35 .  
         [0076]     In this embodiment, a valve structure member  67  is provided within the storage space  51 .  
         [0077]     The valve structure member  67  that is a cylindrical structure is integrally formed to protrude from the bottom wall  33   i  of the lower case  33  at a position on a central line in a widthwise direction of the storage space  51 . The valve structure member  67  has a contact surface  67   b  at a position having the same height as or slightly higher than those of the upper end surfaces of the side container wall  33   f  and the front and rear container walls  33   g  and  33   h , to which the intermediate container wall  35  is to be welded. Further, a positioning protrusion  67   a  having a diameter smaller than the contact surface  67   b  is provided at the center of the upper portion of the valve structure member  67 .  
         [0078]     The total height of the two ink absorption members  63  provided in the storage space  51  is the same as or slightly lower than those of the upper end surfaces of the side container wall  33   f  and the front and rear container walls  33   g  and  33   h . In addition, openings  63   a  are formed to pass through the ink absorption members  63  such that the ink absorption members  63  are disposed to be spaced by a gap from the valve structure member  67 .  
         [0079]     Meanwhile, the circular vent  61  is formed in the intermediate container wall  35  to face the contact surface  67   b  to be then closed by the contact surface. The vent  61  is disposed on the central line in the widthwise direction.  
         [0080]     The contact surface  67   b  of the valve structure member  67  and the vent  61  of the intermediate container wall  35  constitute the valve  65  to be described below.  
         [0081]     Preferably, a position where the valve  65  is to be formed is a position in which the waste ink finally reaches the storage space  51 . In this embodiment, as shown in  FIG. 3 , the vent  61  and the valve structure member  67  are provided at positions in the periphery of the rear end so as not to interfere with the lower ends of the ink packs  11  to  13  and so as to be spaced apart from the waste ink inlet portion  37 .  
         [0082]     In this embodiment, the vent  61  is used to position where the circumferential portion of the intermediate container wall  35  is bonded to the lower case  33 . That is, the portions to be bonded can be accurately positioned only by inserting the positioning protrusion  67   a  into the vent  61 , and aligning the circumferential portion opposite to the vent  61  with the end surfaces of the lower case  33  to be bonded.  
         [0083]     With this configuration, the circumferential portion of the vent  61  in the intermediate container wall  35  bonded to the lower case  33  comes into contact with the contact surface  67   b  of the valve structure member  67 . Then, the vent  61  is closed, as shown in  FIG. 6A .  
         [0084]     As shown in  FIGS. 2 and 3 , in the lower case  33 , an IC module  53  that can record the types of the ink packs  11  to  13 , a residual ink quantity, and other kinds of data is provided on the side container wall  33   f.    
         [0085]     If the ink cartridge  10  is mounted on the cartridge mounting portion  9  of the ink jet printer  1  (see  FIG. 1 ), the IC module  53  is electrically connected to a connection terminal provided in the cartridge mounting portion  9 . Accordingly, information can be read and written from and into a printer control circuit or a computer to which the printer is connected.  
         [0086]     If the lower case  33  shielded by the intermediate container wall  35  after the ink absorption members  63  are provided in the storage space  51  is joined to the upper case  31  that accommodates the ink packs  11  to  13 , the upper case  31  and the lower case  33  are connected to each other by the above-described anchoring protrusions  31   d  and  31   f  and so on. With this procedure, the ink cartridge  10  is assembled.  
         [0087]     In a state where the ink cartridge  10  is mounted on the cartridge mounting portion  9  (see  FIG. 1 ) of the ink jet printer  1 , as shown in  FIG. 5 , the lower ends of the individual ink packs  11  to  13  press and bias the intermediate container wall  35  downward in a direction of an arrow (A) in the drawing. A pressing and biasing force can function as a biasing force for keeping the valve  65  of the waste ink storage structure  17  to be described below to be in a closed state. In this case, the intermediate container wall  35  can be fixed to the lower case  33  with no tension.  
         [0088]     Next, the valve having the above-described configuration will be described in detail.  
         [0089]     As shown in  FIG. 6A , the valve  65  closes the vent  61  by causing the contact surface  67   b  of the valve structure member  67  to come into contact with the perimeter of the vent  61 . The valve  65  is kept in a closed state excluding when waste ink is poured from the waste ink inlet portion  37  (see  FIG. 4 ).  
         [0090]     If a pressure within the storage space  51  increases according to the pouring of waste ink, as shown in  FIG. 6B , the intermediate container wall  35  of the valve  65  is displaced and expanded upward. Then, the perimeter of the vent  61  is spaced away from the contact surface  67   b  of the valve structure member  67 , and thus the valve  65  allows the storage space  51  to be exposed to the atmosphere through the vent  61 .  
         [0091]     Since the vent  61  is disposed on the central line in the widthwise direction, displacement of the intermediate container wall  35  becomes large, and thus an operation pressure as the valve is being reduced. Accordingly, an increase in internal pressure of the storage space  51  is easily prevented. In addition, since displacement at the vent  61  of the intermediate container wall  35  is balanced, the perimeter of the vent  61  can uniformly come into contact with the contact surface  67   b.    
         [0092]     Subsequently, in the valve  65 , if the pouring of waste ink ends and the pressure within the storage space  51  is reduced, as shown in  FIG. 6C , the perimeter of the vent  61  is biased in a direction to be brought into contact with the contact surface  67   b  of the valve structure member  67  by a tension of the intermediate container wall  35  and the ink packs  11  to  13  that press and bias the intermediate container wall  35  downward. Then, the vent  61  is closed.  
         [0093]     If the ink cartridge  10  is mounted on the cartridge mounting portion  9  of the ink jet printer  1 , the ink supply needles  41  provided in the cartridge mounting portion  9  pass through the ink outlet ports  23  in an airtight manner, such that the ink liquids within the bag bodies  21  can be supplied to the printer through the ink supply needles  41 . Supply tubes  42  that supply ink to a printing head (not shown) of the printer are connected to the ink supply needles  41 , respectively.  
         [0094]     Meanwhile, the waste ink pouring needle  47  provided in the cartridge mounting portion  9  is engaged with the rubber mouth member  37   a  in an airtight manner and presses the valve body  37   c  (see  FIG. 4 ). Then, waste ink can be poured into the storage space  51  through the waste ink pouring needle  47 .  
         [0095]     A waste ink guiding tube  49  that guides waste ink generated at the time of an ink filling operation or a head cleaning operation of the ink jet printer  1  is connected to the waste ink pouring needle  47 .  
         [0096]     As shown in  FIG. 4 , a rear end of the waste ink inlet  44  (a right end in  FIG. 4 ) is connected to the storage space  51 . Then, waste ink poured from the waste ink pouring needle  47  inserted into the waste ink inlet portion  37  flows in the storage space  51  from the rear end of the waste ink inlet  44 .  
         [0097]     The ink absorption members  63  absorb poured waste ink so as to prevent waste ink poured into the storage space  51  through the waste ink inlet portion  37  and the waste ink inlet  44  from flowing backward to the waste ink inlet portion  37  and leaking to the outside.  
         [0098]     If waste ink is poured into the storage space  51  that is kept airtight, an air pressure of the storage space  51  is increased, and thus the intermediate container wall  35  is lifted up. Then, a gap is formed between the intermediate container wall  35  and the contact surface  67   b , air within the storage space  51  is released to the outside, and then the air pressure is decreased. Accordingly, the valve  65  is closed again. In such a manner, the valve  65  opens the vent  61  only when waste ink is poured so as to release air within the storage space  51 . Therefore, there is no case where the pouring of waste ink from the waste ink inlet portion  37  is obstructed.  
         [0099]     According to the waste ink storage structure  17  of this embodiment described above, the vent  61  that exposes the storage space  51  to the atmosphere is kept to be in a closed state by the valve  65  excluding when waste ink is poured from the waste ink inlet portion  37 .  
         [0100]     Therefore, moisture of waste ink poured into the storage space  51  is suppressed from being transpired from the vent  61  to the outside, and thus it is possible to prevent hardening of waste ink in the storage space  51 . As a result, it is possible to prevent absorption capability of the ink absorption members  63  from being degraded due to hardening of waste ink.  
         [0101]     Accordingly, even when pigment-based ink is used, the original absorption capability of the ink absorption members  63  can be fully utilized, and the ink absorption members  63  can be stably used to collect waste ink for a long time. Further, since clogging due to hardened waste ink does not occur, there is no case where a pressure in the waste ink guiding tube  49  on the waste ink supplying side connected to the waste ink inlet portion  37  and so on is abnormally increased. Therefore, the occurrence of an inconsistency such as light leakage or the like due to the removal of the waste ink guiding tube  49  or the like can be prevented.  
         [0102]     In the waste ink storage structure  17  of the above-described embodiment, for example, when discarding a used ink cartridge  10 , the upper case  31  and the lower case  33  are separated from each other, and the intermediate container wall  35  formed of a plastic film is removed from the lower case  33 . Then, a surface of the storage space  51  can be largely opened, and thus the ink absorption members  63  having absorbed waste ink can be simply removed from the storage space  51 .  
         [0103]     Therefore, for the purpose of recycling or reusing the parts or materials, disassembling the used ink cartridge  10  and classifying by materials can be easily performed.  
         [0104]     The valve structure member  67  is integrally formed on the bottom wall  33   i  at the position facing the vent  61  that is formed to pass through the intermediate container wall  35  formed of a plastic film. Then, the contact surface  67   b  of the valve structure member  67  comes into contact with the perimeter of the vent  61  so as to close the vent  61 . With this configuration, the valve  65  opens/closes the vent  61  can be obtained. Therefore, parts for providing the valve  65  do not need to be added, and thus costs can be prevented from being increased due to an increase in the number of parts or an increase in the number of assembling steps.  
         [0105]     In the ink cartridge  10  of the above-described embodiment, the intermediate container wall  35  having the vent  61  provided therein defines the ink pack accommodating space  55  that accommodates the ink packs  11  to  13 , and the storage space  51 .  
         [0106]     Accordingly, the vent  61  is not directly exposed the outside of the ink cartridge  10 , but is exposed to the atmosphere through the ink pack accommodating space  55  that accommodates the ink packs  11  to  13 . Therefore, there is no case where a user unexpectedly touches the valve  65  provided at the vent  61  and causes a trouble in valve functions.  
         [0107]     The perimeter of the valve structure member  67  has a space portion  56  so as not to come into contact with the ink absorption members  63 . Therefore, a capillary force does not exert between the valve structure member  67  and the ink absorption members  63 , and waste ink absorbed by the ink absorption members  63  does not move to the contact surface  67   b  through the valve structure member  67 . Therefore, there is no case where waste ink flows out from the vent  61  unless waste ink exceeds the capability of the ink absorption members  63 .  
         [0108]     In this embodiment, the positioning protrusion  67   a  is provided at the contact portion of the valve structure member  67  to pass through the vent  61 .  
         [0109]     Therefore, at the time of assembling, positioning of the contact portion of the valve structure member  67  and the vent  61  of the intermediate container wall  35  can be easily performed, and thus assembling workability can be improved.  
         [0110]     A structure of the ink cartridge having the waste ink storage structure of the invention is not limited to the ink cartridge  10  of the above-described embodiment. For example, the waste ink storage structure of the invention can be applied to various ink cartridges having a different ink pack support structure or a different number of ink packs.  
         [0111]     In this embodiment, the valve structure member is formed integrally with the lower case. However, separate parts for the valve structure member may be provided on the lower case or the valve structure member may be formed by a circumferential portion of the lower case. In any case, what is necessary is that a surface for closing the vent is provided.  
         [0112]     In the above-described embodiment, a case where the waste ink storage structure  17  is provided in the ink cartridge  10  that is detachably mounted on the ink jet printer  1  has been described. However, the waste ink storage structure of the invention is not limited to this configuration. Of course, various examples can be used.  
         [0113]     Next, a second embodiment according to the invention will be described with reference to the drawings.  
         [0114]      FIG. 7  is an exploded perspective view schematically showing the overall configuration of an ink jet printer on which a waste ink tank having a waste ink storage structure is provided.  FIG. 8  is an exploded perspective view of a waste ink tank shown in  FIG. 7 .  FIG. 9  is an expanded cross-sectional view of a valve shown in  FIG. 8 .  
         [0115]     As shown in  FIG. 7 , an ink jet printer  101  of this embodiment has a printer housing  111  that is to be a bottom casing, a waste ink tank  120  that is detachably provided in a tank accommodating portion ills defined at a bottom portion within the printer housing  111  and has a rectangular shape in plan view, a printer mechanism section  115  that is disposed above the printer housing  111  and the waste ink tank  120 , and an exterior cover  112  that is to be a top casing. Further, a power supply unit  116  is provided at the back of the tank accommodating portion ills that accommodates the waste ink tank  120 .  
         [0116]     As shown in  FIG. 8 , the waste ink tank  120  of this embodiment has a boxlike tank main body  121  that replaceably accommodates an ink absorption member  122  for absorbing waste ink poured into a storage space  151 , and a lid body  124  that covers an upper opening of the tank main body  121 . Portions of the tank main body  121  and the lid body  124  to be bonded are pressed into contact with each other through a sealing member  123 , such as a rubber packing or the like, and is sealed fluid-tight.  
         [0117]     Tubes  125  are provided on the rear surface of the lid body  124  so as to guide waste ink from an ink receiving port  127  of a tank circumferential portion to a tank central portion and cause waste ink to drip on an upper central portion of the ink absorption member  122 . A color of a plastic part constituting the waste ink tank  120  is a dark color, for example, black such that waste ink to be stored is not visible.  
         [0118]     The waste ink tank  120  is fitted and screwed to the tank accommodating portion ills on the printer housing  111 , and an ejection port of an absorption pump (not shown) for head cleaning and front end inlet ports  125   a  of the tubes  125  are connected to each other on the waste ink tank  120 , such that the waste ink tank  120  is set on the printer housing  111 . Further, when removing the waste ink tank  120 , a reverse operation is performed, such that the waste ink tank  120  can be removed from the printer housing  111 .  
         [0119]     The ink absorption member  122  is a laminate that is formed by laminating multi-stage (in the drawing, four-stage) thin plate molded bodies formed of a nonwoven fabric or felt from the uppermost layer to the lowermost layer ( 122 A to  122 D). Further, a center hole  122   f  is provided at a planar center of each of the three-stage ink absorption members  122 B to  122 D, excluding the lowermost ink absorption member  122 A, so as to vertically pass therethrough. In the uppermost ink absorption member  122 D, a tube accommodating groove  122   g  that extends from its circumferential portion to the center hole  122   f  is formed.  
         [0120]     Then, the tubes  125  are accommodated in the tube accommodating groove  122   g  formed in the uppermost ink absorption member  122 D, and the front end inlet ports  125   a  of the tubes  125  are positioned in the ink receiving port  127  provided at the circumferential portion of the lid body  124 . Simultaneously, front end outlet ports  125   b  of the tubes  125  are positioned within the center hole  122   f  of the uppermost ink absorption member  122 D.  
         [0121]     That is, the waste ink tank  120  of this embodiment has, in the lid body  124 , the waste ink storage structure  17  provided with the ink receiving port  127  that is to be a waste ink inlet portion for pouring waste ink into the storage space  151 , and a vent  173  that exposes the storage space  51  to the atmosphere. The lid body  124  serves as a container wall that defines the storage space  151  for storing waste ink generated at the time of an ink filling operation or a head cleaning operation of the printer. The vent  173  is located at a central portion of the lid body  124 , as shown in  FIG. 8 . The vent  173  is disposed at a center of the center hole  122   f  so as not to come into contact with the ink absorption member  122 .  
         [0122]     As shown in  FIG. 9 , a valve  171  that is opened only when waste ink is poured is provided at the vent  173  formed in the lid body  124 . A valve body  174  of the valve  171  that closes the vent  173  formed in the lid body  124  is integrally molded by an elastic member having open/close portions  174   c  that are elastically displaced in an opening direction by a pouring pressure of waste ink from the ink receiving port  127 .  
         [0123]     The valve body  174  has a brim portion  174   a  that is closely bonded to the circumferential portion of the vent  173 , a cylindrical portion  174   b  that passes through the vent  173  from the inner circumferential portion of the brim portion  174   a , and a plurality of open/close portions  174   c  that are formed by providing a widthwise notch  174   d  at a conical portion extending from the front end of the cylindrical portion  174   b  so as to close the front end of the cylindrical portion  174   b . The brim portion  174   a , the cylindrical portion  174   b , and the open/close portions  174   c  are integrally formed using a rubber material.  
         [0124]     The open/close portions  174   c  of the valve  171  are closed when waste ink is not poured, as shown in  FIG. 9A . Meanwhile, when waste ink is poured, as shown in  FIG. 9B , the open/close portions  171  are elastically displaced in the opening direction by the pouring pressure of waste ink from the ink receiving port  127 , and the notch  174   d  is opened. Then, air within the storage space  151  is released to the outside.  
         [0125]     Accordingly, an exclusive-use valve body  174  constituting the valve  171  needs to be provided. However, by suitably setting elasticity in the open/close portions  174   c  of the valve body  174 , sealing capability of the vent  173  by the valve  171  can be improved, and also capability for preventing transpiration of moisture from the vent  173  can be improved.  
         [0126]     A material for the lid body  124  having the vent  173  provided therein is not limited. Therefore, a degree of freedom for design of the waste ink tank  120  having the waste ink storage structure can be improved.  
         [0127]     According to the waste ink tank  120  of the above-described embodiment, moisture of waste ink poured into the storage space  151  is suppressed from being transpired from the vent  173  to the outside. Therefore, it is possible to obtain a waste ink tank that can prevent hardening of waste ink in the storage space  151 , and can prevent absorption capability of the ink absorption member  122  from being degraded due to hardening of waste ink.  
         [0128]     In the ink jet printer  101  of this embodiment, only the waste ink tank  120  can be independently removed from the printer housing  111 . Therefore, only the waste ink tank  120  that is stained with ink can be separately managed, and the non-stained printer housing  111  can be recycled or reused as it is. In addition, since the waste ink tank  120  is detachably provided, in a certain situation, a worker can replace only the waste ink tank  120  with a new one without staining his/her hands.  
         [0129]     According to this embodiment, when discarding the used waste ink tank  120 , disassembling can be simply performed by opening the lid body  124 , removing the ink absorption member  122  having absorbed waste ink from the tank main body  121 , and then removing the valve body  174  or the tubes  125  from the lid body  124 .  
         [0130]     Therefore, for the sake of recycling or reusing the parts or materials, works for disassembling the used waste ink tank  120  and classifying by materials can be easily performed.  
         [0131]     The configuration of the valve, into which the valve body having the open/close portions to be opened by the pouring pressure of waste ink from the waste ink inlet portion is incorporated, is not limited to the configuration of the valve  171 . Of course, various examples can be used.  
         [0132]     A valve  175  shown in  FIG. 10  has a cylindrical valve seat  177  that is threaded and fixed in a vent of a contain wall (not shown), and a valve body  178  that is seated on the valve seat  177 .  
         [0133]     The valve seat  177  sets a contact surface  177   a  formed in an inner circumferential surface of a cylinder as a seating surface of the valve body  178 . In the valve body  178 , a disc-shaped valve main body  178   a , an outer circumferential portion of which is seated on the contact surface  177   a , and a support portion  178   b  that supports a central portion of the valve main body  178   a  are integrally formed using an elastic material.  
         [0134]     As indicated by a two-dot-chain line in the drawing, the outer circumferential portion of the valve main body  78   a  is elastically displaced in a direction to be spaced away from the valve seat  77  according to an increase in pressure of the storage space when waste ink is poured. Then, as indicated by a solid line in the drawing, air of the storage space can be released from a gap, which is to be formed when the valve main body  78   a  is elastically displaced, to the outside.