Abstract:
There is provided an ink cartridge including a first ink chamber, a second ink chamber, an ink-flow check portion and a pressure control portion. The first ink chamber is configured to store ink therein. The second ink chamber is in fluid communication with the first ink chamber via a first path, the second ink chamber defining therein a volume. The ink-flow check portion is configured to allow the ink to flow from the first ink chamber to the second ink chamber and block the ink from flowing from the second ink chamber to the first ink chamber. The pressure control portion is configured to control an internal pressure of the second ink chamber.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority from Japanese Patent Application No. 2010-137812 filed Jun. 17, 2010. The entire content of the priority application is incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to an ink cartridge insertable into an image recording apparatus provided with a hollow needle for allowing ink to flow outside of the ink cartridge via the needle. 
     BACKGROUND 
     In a known ink-jet recording apparatus, ink is supplied from an ink cartridge to a recording head via a tube. The ink-jet recording apparatus is provided with a cartridge installation portion on which the ink cartridge is detachably installable. When installed, the ink cartridge is connected to the recording head via the tube, thereby forming an ink passage between the ink cartridge and the recording head. 
     The ink cartridge includes an ink chamber for storing ink, an ink supplying section for allowing the ink to be supplied to outside via a valve or a seal, and a path connecting the ink chamber and the ink supplying section. The ink supplying section is provided with an accommodation chamber for accommodating the valve or the seal. When the ink cartridge is installed in the cartridge installation portion, a hollow needle provided in the cartridge installation portion is inserted into the accommodation chamber to move the valve or to break the seal, whereupon the ink can be supplied to the hollow needle. Further, a check valve is provided in the path in order to block the ink from flowing back into the ink chamber from the ink supplying section. 
     SUMMARY 
     When the hollow needle is inserted into the accommodation chamber, the ink within the accommodation chamber is pushed by an amount equal to a volume of the inserted hollow needle, thereby causing pressure within the accommodation chamber to increase. In response, the ink tries to flow either into the ink chamber or to outside. At this time, due to the check valve positioned in the path, the ink is not able to flow into the ink chamber but flows into the recording head via the hollow needle. The recording head is provided on a carriage having a sub tank whose portion is made up of a deformable film. When the ink flows into the sub tank, the film of the sub tank deforms and absorbs a pressure change that occurs within the sub tank. While the deformed film restores its original shape, the ink flows back from the sub tank to the accommodation chamber. 
     If the ink cartridge is removed from the cartridge installation portion during the period in which the ink flows out of the accommodation chamber and then comes back thereto from the sub tank, the ink, which is supposed to go back to the accommodation chamber, may be dripping down from the needle. In this case, the fallen ink could contaminate the cartridge installation portion and adhere to an outer casing of ink cartridge. Further, the ink deposited on the outer casing of the ink cartridge could scatter around a circuit board of the recording apparatus when the ink cartridge is being installed in/removed from the cartridge installation portion, which may possibly cause an electrical trouble and corrosion. 
     In view of the foregoing, it is an object of the present invention to provide an ink cartridge capable of suppressing an amount of ink flowing to a recording head of a recording apparatus at the time of installation of the ink cartridge in the recording apparatus. 
     In order to attain the above and other objects, the present invention provides an ink cartridge including a first ink chamber, a second ink chamber, an ink-flow check portion and a pressure control portion. The first ink chamber is configured to store ink therein. The second ink chamber is in fluid communication with the first ink chamber via a first path, the second ink chamber defining therein a volume. The ink-flow check portion is configured to allow the ink to flow from the first ink chamber to the second ink chamber and block the ink from flowing from the second ink chamber to the first ink chamber. The pressure control portion is configured to control an internal pressure of the second ink chamber. 
     According to another aspect of the present invention, there is provided an image recording apparatus including an ink cartridge, a needle, a fourth ink chamber and a recording head. The ink cartridge includes a first ink chamber configured to store ink therein; a second ink chamber that is in fluid communication with the first ink chamber via a first path, the second ink chamber having an outlet port, and the second ink chamber defining therein a volume; an ink-flow check portion configured to allow the ink to flow from the first ink chamber to the second ink chamber and block the ink from flowing from the second ink chamber to the first ink chamber; and a pressure control portion configured to control an internal pressure of the second ink chamber. The needle is configured to be inserted into the outlet port of the second ink chamber. The fourth ink chamber is configured to store the ink flowing out of the second ink chamber via the needle, the fourth ink chamber defining therein a volume that is allowed to change in accordance with a change in the internal pressure of the second ink chamber. The ink is then supplied from the fourth ink chamber to the recording head. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a cross-sectional diagram conceptually illustrating an internal structure of a printer incorporating an ink cartridge according to a first embodiment of the present invention; 
         FIG. 2  is a perspective view showing an exterior of the ink cartridge according to the first embodiment; 
         FIG. 3  is a perspective view showing an internal structure of the ink cartridge according to the first embodiment; 
         FIG. 4  is a right side view of the internal structure of the ink cartridge according to the first embodiment; 
         FIG. 5  is an exploded perspective view showing the internal structure of the ink cartridge according to the first embodiment; 
         FIG. 6  is a partially enlarged perspective view showing a cross-section of the ink cartridge according to the first embodiment taken along a plane including a line VI-VI shown in  FIG. 4 ; 
         FIG. 7  is a plan view of a cross-section of a valve accommodation chamber of the ink cartridge of  FIG. 6  as viewed from a direction VII shown in  FIG. 6 ; 
         FIG. 8  is an enlarged perspective view showing the cross-section of the valve accommodation chamber according to the first embodiment, in which an ink needle is inserted into the valve accommodation chamber; 
         FIG. 9  is a plan view of the cross-section of the valve accommodation chamber of  FIG. 8  as viewed from a direction IX shown in  FIG. 8 ; 
         FIG. 10  is a perspective view showing an internal structure of an ink cartridge according to a second embodiment of the present invention; 
         FIG. 11  is a right side view of the internal structure of ink cartridge according to the second embodiment; and 
         FIG. 12  is a partially enlarged perspective view of a cross-section of the ink cartridge according to the second embodiment taken along a plane including a line XII-XII shown in  FIG. 11 . 
     
    
    
     DETAILED DESCRIPTION 
     An ink cartridge  30  according to a first embodiment of the present invention will be described with reference to  FIGS. 1 through 9 . 
     First, a general configuration of a printer  10  in which the ink cartridge  30  is accommodated will be described with reference to  FIG. 1 . The terms “upward”, “downward”, “upper”, “lower”, “above”, “below”, “beneath”, “right”, “left”, “front”, “rear” and the like will be used throughout the description assuming that the printer  10  is disposed in an orientation in which it is intended to be used. 
     The printer  10  is a color ink-jet recording apparatus that forms an image on a recording medium (a sheet of paper in the present embodiment) by selectively ejecting ink droplets. The printer  10  includes an ink supplying unit  100 , a carriage  21  and four ink tubes  20  connecting therebetween in correspondence with four colors of ink, as shown in  FIG. 1 . For simplicity, only one ink tube  20  is depicted in  FIG. 1 . 
     The ink supplying unit  100  includes a cartridge case  110  adapted for detachably accommodating four kinds of ink cartridges  30 . Each ink cartridge  30  stores ink of one of four colors: cyan, magenta, yellow and black. The cartridge case  110  is formed with an opening  112  through which the four ink cartridges  30  are loaded into or unloaded from the cartridge case  110  in a substantially horizontal direction (i.e., a left-to-right direction in  FIG. 1 ). 
     The opening  112  is covered with a cover  19  that is pivotably movably supported to a frame (not shown) of the printer  10 . The cover  19  is pivotally movable about a shaft  114  provided at a lower end of the opening  112  to open and close the opening  112 . 
     The cartridge case  110  has an end wall on which four ink needles  111  are provided. Each ink needle  111  is a tubular-shaped silicon member, protruding toward the opening  112  of the cartridge case  110 . Each ink needle  111  has one end connected to the corresponding ink tube  20  and another end on which a cut-out  113  is formed (see  FIGS. 8 and 9 ). The ink needle  111  is formed with an internal space that extends through the ink needle  111 . When the ink cartridge  30  is installed in the cartridge case  110 , the corresponding ink needle  111  is inserted into the ink cartridge  30 , whereupon the ink within the ink cartridge  30  flows into the ink needle  111  via the cut-out  113 . The ink is then supplied to a corresponding sub tank  28  (described next) provided in the carriage  21  via the ink tube  20  of the corresponding color. 
     The carriage  21  includes a recording head  29  and four sub tanks  28  each corresponding to one of the four colors. The each sub tank  28  temporarily stores ink of the corresponding color supplied from the ink cartridge  30  of the same color via the corresponding ink tube  20 . The recording head  29  is connected to each sub tank  28  via an ink passage  27  provided in correspondence with each sub tank  28 . The recording head  29  is thus connected to each ink cartridge  30  via the corresponding ink needle  111 , ink tube  20 , sub tank  28  and ink passage  27 . The recording head  29  selectively ejects the ink supplied from the ink cartridges  30  in a form of fine ink droplet. 
     Each sub tank  28  has an upper wall made of a deformable flexible film. This flexibility of the film enables a volume of the sub tank  28  to change, thereby absorbing pressure changes within the sub tank  28 . 
     The printer  10  also includes a sheet supply tray  15 , a sheet supply roller  23 , a sheet passage  24 , a pair of conveyor rollers  25 , a platen  26 , a pair of discharge rollers  22 , and a discharge tray  16  arranged in this order in a sheet feeding direction. The sheet supplied from the sheet supply tray  15  to the sheet passage  24  by the sheet supply roller  23  is conveyed to the platen  26  by the pair of conveyor rollers  25 . When the sheet is placed on the platen  26 , the recording head  29  selectively ejects ink onto the sheet while moving back and forth, along with the carriage  21 , in two linear directions that are perpendicular to the sheet feeding direction and parallel to the surface of the sheet. In this way, images are formed on the sheet. Then, the ink is selectively ejected from the recording head  29  onto the sheet passing through the platen  26  to form an inked image on the sheet. The sheet is then discharged onto the discharge tray  16  by the pair of discharge rollers  22 . 
     Next, a detailed configuration of the ink cartridge  30  according to the first embodiment will be explained with reference to  FIGS. 2 through 9 . 
     The ink cartridge  30  is a container for storing ink therein. The ink cartridge  30  is loaded into the cartridge case  110  in a direction indicated by an arrow  104  as shown in  FIG. 2  (to be referred to as “insertion direction”). When installed in the cartridge case  110 , the ink cartridge  30  is held in an upright posture shown in  FIG. 2 . Each ink cartridge  30  has a shape identical to one another except that each accommodates ink of a different color. 
     The ink cartridge  30  has a substantially flat parallelepiped shape. In the upright posture shown in  FIG. 2 , the ink cartridge  30  has a small width (in a direction indicated by an arrow  101  which will be referred to as widthwise direction or horizontal direction), a height (in a direction indicated by an arrow  102  which will be referred to as a vertical direction that is perpendicular to the widthwise direction) and a depth (in a direction indicated by an arrow  103  which will be referred to as a depthwise direction which is perpendicular to the widthwise direction and the vertical direction) those greater than the width. The ink cartridge  30  has an outer casing  31  within which an internal structure of the ink cartridge  30  is accommodated. 
     As shown in  FIGS. 3 through 5 , the internal structure of the ink cartridge  30  includes a frame  32 , an air communication valve  50 , an ink supply valve  60  and films  33 ,  34 . The frame  32  and the films  33 ,  34  define an ink chamber  36  for accommodating ink therein. A detailed structure provided within the ink chamber  36  (for example, ribs for maintaining rigidity and a mechanism for detecting an amount of ink) will not be described here for the sake of simplification. 
     The frame  32  is formed of a synthetic resin capable of transmitting light emitted from a light sensor, such as infrared ray. The frame  32  may be formed of any types of resin, such as a transparent or translucent resin, provided that the resin has a light-transmissive capability. For example, polyacetal, nylon, polyethylene or polypropylene is available. 
     The frame  32  has a front wall  41 , an upper wall  42 , a rear wall  43  and a bottom wall  44 . As shown in  FIGS. 3 through 5 , the front wall  41 , the upper wall  42 , the rear wall  43  and the bottom wall  44  integrally form a substantially tubular shape so that the frame  32  is formed with a right surface  46  and a left surface  45  each having an opening therein. 
     The films  33 ,  34  are made of a thin-walled transparent resin, and have a flexible, stretchable or elastically deformable characteristic. The films  33 ,  34  are respectively attached to the right surface  46  and the left surface  45  of the frame  32 , more specifically, to peripheral portions of the right surface  46  and the left surface  45  by ultrasonic welding. Alternatively, the films  33 ,  34  may be thermally welded to the frame  32 . The films  33 ,  34  thus close the openings formed in the right surface  46  and the left surface  45  respectively. A space bounded by the frame  32  and the films  33 ,  34  is defined as the ink chamber  36 . 
     In the first embodiment, the ink chamber  36  is formed such that the films  33 ,  34  cover the openings formed on both of the left surface  45  and the right surface  46  of the frame  32 . However, the frame  32  may be formed into a box shape having only one opening formed on either one of the left surface  45  and the right surface  46 . In this case, the sole opening is covered by a film to define the ink chamber  36  within the frame  32 . 
     An air valve accommodation chamber  48  is formed on the front wall  41  of the frame  32  at a position adjacent to the upper wall  42 , as shown in  FIGS. 3 through 5 . The air valve accommodation chamber  48  protrudes frontward in the insertion direction  104  and has a cylindrical shape. The air valve accommodation chamber  48  has a tip end portion on which a circular-shaped air outlet port  47  is formed. The air valve accommodation chamber  48  also has a portion that protrudes inward of the frame  32 . The air valve accommodation chamber  48  has a depth end opposite to the air outlet port  47  that is in communication with the ink chamber  36 . The air valve accommodation chamber  48  accommodates the air communication valve  50  therein. 
     As shown in  FIG. 5 , the air communication valve  50  is a valve mechanism to open and close an air-flow passage formed between the air outlet port  47  and the ink chamber  36  (specifically, an air confined in the ink chamber  36 ). The air communication valve  50  includes a compression spring  51 , a valve main body  52 , a sealing member  53  and a cap  54 , each of which is formed of a resin such as polyacetal and silicon rubber. The compression spring  51  and the valve main body  52  are accommodated within the air valve accommodation chamber  48 , while the sealing member  53  and the cap  54  are assembled so as to be coaxially aligned with the air outlet port  47 . 
     More specifically, the valve main body  52  is disposed within the air valve accommodation chamber  48  so as to be movable in the depthwise direction  103 . The valve main body  52  includes a lid  55  and a rod  56 . The rod  56  extends from a center of the lid  55 , passing through the center of the air outlet port  47 , and protrudes outward of the air outlet port  47 . The sealing member  53  and the cap  54  are respectively formed with a through-hole at a center thereof through which the rod  56  penetrates. When assembled, the rod  56  is exposed to outside of the air valve accommodation chamber  48  via the air outlet port  47 . 
     The compression spring  51  biases the valve main body  52  toward the sealing member  53  such that the lid  55  is pressed against the sealing member  53 . Therefore, the lid  55  is in intimate contact with the sealing member  53 . With this structure, the air communication valve  50  normally serves to close the air-flow passage between the air valve accommodation chamber  48  and the atmosphere (outside of the ink cartridge  30 ). 
     While the ink cartridge  30  is being inserted into the cartridge case  110 , the rod  56  is pushed toward the depth end of the air valve accommodation chamber  48  (toward the ink chamber  36 ) to separate the lid  55  from the sealing member  53  against the biasing force of the compression spring  51 . As a result, the air-flow passage is opened for introducing air from outside into the ink chamber  36  through the air valve accommodation chamber  48 . At this time, due to the air flowing into the ink chamber  36 , the inner pressure within the ink chamber  36  becomes equal to the atmospheric pressure. The air communication valve  50  may not necessarily be provided if the ink chamber  36  is maintained to have negative pressure therewithin. Further, instead of the air communication valve  50 , at least a passage may be provided for allowing air communication between the ink chamber  36  and the atmosphere. 
     On the front wall  41  of the frame  32 , an ink valve accommodation chamber  58  is also formed at a position adjacent to the bottom wall  44 . The ink valve accommodation chamber  58  protrudes frontward in the insertion direction  104  and is of a cylindrical shape. The ink valve accommodation chamber  58  has a tip end portion on which a circular-shaped ink outlet port  57  is formed. The ink valve accommodation chamber  58  also has a portion that protrudes inward of the frame  32  (toward the ink chamber  36 ). The ink valve accommodation chamber  58  has a depth end opposite the ink outlet port  57  that is in communication with the ink chamber  36 . The ink valve accommodation chamber  58  accommodates the ink supply valve  60  therein. 
     More specifically, as shown in  FIGS. 6 and 7 , a partitioning wall  49  is formed between the depth end of the ink valve accommodation chamber  58  and the ink chamber  36 . The partitioning wall  49  is formed with a through-hole  59  for introducing ink from the ink chamber  36  into the ink valve accommodation chamber  58 . The ink supply valve  60  is a valve mechanism that serves to open and close the through-hole  59 . The ink valve accommodation chamber  58  is allowed to be in communication with the ink chamber  36  via the through-hole  59  when the ink supply valve  60  opens the through-hole  59 . The through-hole  59  is therefore to be referred to as “ink-flow passage  59 .” 
     As shown in  FIG. 5 , the ink supply valve  60  includes a valve member  61 , a valve seat  62 , a compression spring  63 , a valve main body  64 , a sealing member  65  and a cap  66 , each of which is formed of a resin, for example, polyacetal and silicon rubber. The valve member  61 , the valve seat  62 , the compression spring  63  and the valve main body  64  are accommodated within the ink valve accommodation chamber  58 , while the sealing member  65  and the cap  66  are coaxially assembled to the ink outlet port  57 . 
     As shown in  FIG. 6 , the valve member  61  is positioned on the depth end of the ink valve accommodation chamber  58 . While being coupled to the valve seat  62 , the valve member  61  is elastically deformable such that the valve member  61  can be in contact with or in separation from the partitioning wall  49 . In other words, the valve member  61  serves as a check valve for opening or closing the ink-flow passage  59  formed on the partitioning wall  49 . The valve member  61  is made of a silicon rubber, for example, and is formed by injection molding. The valve member  61  is a ring-shaped or hollow member having two opposing openings. One of the openings is in confrontation with the valve seat  62 , while the other opening faces the depth end of the ink valve accommodation chamber  58 . The depth-side opening of the valve member  61  is substantially covered with a wall  67 . More specifically, as shown in  FIGS. 6 through 8 , the depth-side opening of the valve member  61  is not totally covered with the wall  67  since the wall  67  is formed with a through-hole  68  that allows ink to flow therethrough. The wall  67  further has a central portion on which a hemispherical section  69  is formed. In accordance with elastic deformation of the wall  67 , the hemispherical section  69  is urged to move so as to open and close the ink-flow passage  59  of the partitioning wall  49 . 
     The valve seat  62  has a tubular shape. The valve seat  62  accommodates therewithin the valve member  61  and is coupled to the valve member  61 . The valve seat  62  is formed of a resin, such as polypropylene, by using injection molding. The valve seat  62  includes a base member  70  and a receiving member  71 . The base member  70  has a tubular shape and penetrates through the compression spring  63  so as to be engaged with the same. The base member  70  also supports the valve main body  64  such that the valve main body  64  is slidably movable within the base member  70  in the depthwise direction  103 . 
     The receiving member  71  is coupled to an end of the base member  70 , the end facing the valve member  61 . The receiving member  71  has a cylindrical shape to be fittingly accommodated in the ink valve accommodation chamber  58 . The receiving member  71  has a depth end on which a flange portion  72  is formed, the depth end being in contact with the partitioning wall  49 . The flange portion  72  protrudes radially inward from the receiving member  71 . The flange portion  72  enables the valve member  61  to be positioned between the receiving member  71  and the base member  70 . 
     When the ink supply valve  60  is assembled, the receiving member  71  is tightly pressed against the partitioning wall  49  due to the biasing force of the compression spring  63 . The receiving member  71  between the valve member  61  and the partitioning wall  49  allows a space to be formed therebetween, thereby enabling the hemispherical section  69  to separate from the ink-flow passage  59  (in this state, the hemispherical section  69  is at its original position). In other words, the valve member  61  opens the ink-flow passage  59 . As a result, the ink accommodated within the ink chamber  36  is allowed to flow into the ink valve accommodation chamber  58  through the ink-flow passage  59  and the through-hole  68  of the valve member  61 . 
     When the ink flows into the ink chamber  36  from the ink valve accommodation chamber  58 , the wall  67  of the valve member  61  elastically deforms toward the partitioning wall  49 , which causes the hemispherical section  69  to be in intimate contact with the ink-flow passage  59 . The ink-flow passage  59  is therefore closed, preventing the ink from flowing back to the ink chamber  36  from the ink valve accommodation chamber  58 . When the ink is not allowed to flow into the ink chamber  36  from the ink valve accommodation chamber  58 , the hemispherical section  69  moves back to the original position due to the elastic force of the valve member  61  and separates from the ink-flow passage  59 . In this way, the valve member  61  serves as a check valve for allowing ink to flow into the ink valve accommodation chamber  58  from the ink chamber  36 , as well as for preventing ink from flowing back to the ink chamber  36  from the ink valve accommodation chamber  58 . 
     As shown in  FIGS. 6 and 7 , the compression spring  63  is disposed between the base member  70  and the valve main body  64  in a compressed state. The compression spring  63  biases the base member  70  and the receiving member  71  toward the partitioning wall  49 , whereas biasing the valve main body  64  toward the sealing member  65 . 
     The valve main body  64  includes a disc-shaped portion  74  and a rod-like portion  75 , as shown in  FIGS. 6 and 7 . The disc-shaped portion  74  is disposed in opposition to the sealing member  65  and in intimate contact therewith due to the biasing force of the compression spring  63 . The rod-like portion  75  protrudes from the disc-shaped portion  74 , and is inserted into an internal space formed within the base member  70 . The base member  70  serves to guide movement of the rod-like portion  75  in the depthwise direction  103  so that the disc-shaped portion  74  can slidably move so as to be in separation from and in contact with the sealing member  65 . 
     The sealing member  65  is fitted to the ink outlet port  57  due to the cap  66 . The sealing member  65  is formed of an elastically deformable resin, such as rubber, to have a high sealing performance. The sealing member  65  has a disk-like shape and is formed with a through-hole  73  at a center thereof. When the sealing member  65  is tightly pressed against the valve main body  64  (the disc-shaped portion  74 ), the through-hole  73  is closed. When the valve main body  64  separates from the sealing member  65  against the biasing force of the compression spring  63 , the through-hole  73  is opened. The sealing member  65  and the disc-shaped portion  74  define a portion of the ink valve accommodation chamber  58 . 
     The valve main body  64  separates from the sealing member  65  when the ink needle  111  is inserted into the through-hole  73  for installation of the ink cartridge  30  into the cartridge case  110 . In other words, when the ink cartridge  30  is loaded, the through-hole  73  is opened for enabling the ink to flow out of the ink valve accommodation chamber  58 . 
     Since a gap or space is formed between each component of the ink supply valve  60 , ink flowing into the ink valve accommodation chamber  58  is allowed to reach the sealing member  65  through the ink supply valve  60 . When the through-hole  73  of the sealing member  65  is opened, the ink within the ink valve accommodation chamber  58  is released to outside. The through-hole  73  has a diameter smaller than that of an outer circumferential surface of the ink needle  111 . Hence, when the ink needle  111  is inserted into the through-hole  73 , the outer circumferential surface of the ink needle  111  is elastically brought into tight contact with the through-hole  73 . This configuration can prevent the ink from leaking between the through-hole  73  and the ink needle  111 . 
     As shown in  FIGS. 6 ,  7  and  9 , the ink valve accommodation chamber  58  is formed with an opening  78  on a wall facing the right surface  46  of the frame  32 . Through the opening  78 , the ink valve accommodation chamber  58  is in communication with a space  76  that opens toward the right surface  46 . The space  76  extends downward from the ink valve accommodation chamber  58 , and is bounded by a periphery  77  that constitutes the right surface  46  of the frame  32  together with the front wall  41 , the upper wall  42 , the rear wall  43  and the bottom wall  44  (also see  FIG. 4 ). The periphery  77  is covered with the film  33  by ultrasonic welding to close the space  76 . The space  76  is thus provided with a flat surface formed of the film  33 . This surface of the space  76  has an area greatest among other flat surfaces constituting the space  76 . The space  76  and the ink valve accommodation chamber  58  thus integrally serve as a secondary ink chamber for temporarily storing ink therein. With provision of the deformable film  33  as the largest flat surface, this secondary ink chamber is allowed to have an expandable volume. More specifically, as indicated by a broken line in  FIG. 9 , the film  33  can deform such that the volume of the secondary ink chamber can increase, i.e., the film  33  can deform outward so as to expand the volume of the secondary ink chamber. 
     Upon insertion of the ink needle  111  into the through-hole  73 , the ink flows into the internal space of the ink needle  111  via the cut-out  113  of the ink needle  111 . When the ink needle  111  enters into the ink valve accommodation chamber  58 , the valve main body  64 , which has closed the through-hole  73 , is separated from the sealing member  65  against the biasing force of the compression spring  63  as shown in  FIGS. 8 and 9 . 
     Within the ink valve accommodation chamber  58 , an amount of space capable of accommodating ink therein is reduced by an amount equal to a volume of the inserted ink needle  111 . As a result, an internal pressure (an ink pressure and an air pressure) of the ink valve accommodation chamber  58  increases. This rise in the internal pressure of the ink valve accommodation chamber  58  causes the valve member  61  to elastically deform such that the hemispherical section  69  closes the ink-flow passage  59 , thereby preventing the ink within the ink valve accommodation chamber  58  from flowing back into the ink chamber  36 . At this time, as shown by the broken line in  FIG. 9 , the film  33  covering the space  76  expands outward due to the increase in the internal pressure, enlarging the volume of ink valve accommodation chamber  58 . The enlarged volume of the ink valve accommodation chamber  58  serves to absorb the rise in the internal pressure therewithin. In this way, the internal pressure within of the ink valve accommodation chamber  58 , which has temporarily increased by the insertion of the ink needle  111 , comes back to a normal level. 
     As described above, the film  33  can elastically deform so as to expand the volume of the ink valve accommodation chamber  58  that has increased due to the insertion of the ink needle  111 . This configuration serves to suppress the rise in the internal pressure of the ink valve accommodation chamber  58 , thereby preventing the ink from flowing out of the ink valve accommodation chamber  58  into the ink tube  20  through the ink needle  111 . In this way, even when the sub tanks  28  are provided on the carriage  21 , the ink is prevented from flowing into the sub tank  28  at the time of installation of the ink cartridge  30  and also from flowing back into the ink needle  111  as a reaction. Further, since the amount of ink flowing into the sub tank  28  is reduced, rise in pressure within the recording head  29  can also be reduced. Therefore, there arises a lower possibility that meniscus of the ink is destroyed at the recording head  29 . 
     Further, the deformable wall of the ink cartridge  30  is realized by welding the film  33  to the periphery  77 . Hence, the deformable wall can be obtained easily and at a lower cost. 
     Further, the deformable wall has the area largest among all the flat walls constituting the ink valve accommodation chamber  58  (or the secondary ink chamber). Therefore, changes in the volume of the ink valve accommodation chamber  58  can also be made large. That is, as the area of the deformable wall is greater, the expandable volume of the ink valve accommodation chamber  58  increases. 
     Further, the film  33  also serves to constitute a portion of the ink chamber  36 . In other words, a single film (the film  33 ) can form the ink chamber  36  and the deformable wall of the ink valve accommodation chamber  58 . Hence, the manufacturing process of the ink cartridge  30  can be simplified. 
     Next, an ink cartridge  130  according to a second embodiment of the present invention will be described with reference to  FIGS. 10 through 12  wherein like parts and components are designated by the same reference numerals to avoid duplicating description. 
     The ink cartridge  130  according to the second embodiment is different from the ink cartridge  30  in that the ink cartridge  130  is provided with an ink buffer chamber  80 , instead of the space  76 . Therefore, a detailed configuration in the vicinity of the ink buffer chamber  80  only will be described. 
     As shown in  FIGS. 10 through 12 , the ink valve accommodation chamber  58  is formed with a path  82  on the wall facing the right surface  46  of the frame  32 . The path  82  extends upward from the ink valve accommodation chamber  58 , bends toward the rear wall  43  and then extends upward up to a position above the ink chamber  36  where the path  82  is connected to the ink buffer chamber  80 . The path  82  is formed with a periphery  81  extending along the path  82 . The ink buffer chamber  80  and the periphery  81  constitute the right surface  46  together with the front wall  41 , the upper wall  42 , the rear wall  43  and the bottom wall  44 . Although not shown in the drawings, the film  33  is attached to the periphery  81  by ultrasonic welding. In the second embodiment, a flat surface configured of the film  33  welded to the periphery  81  has an area greatest among other flat surfaces constituting the ink valve accommodation chamber  58 . Being welded to the periphery  81 , the film  33  is elastically deformable such that a volume of the ink buffer chamber  80  can expand, i.e., the film  33  can deform outward in the widthwise direction  101 . 
     The ink buffer chamber  80  and the path  82  are filled with an ink absorbing member  83 . The ink absorbing member  83  is made of a sponge or nonwoven fabric, for example, and serves to absorb and retain ink therein. Due to the existence of the ink absorbing member  83  within the ink buffer chamber  80  and the path  82 , the ink flowing out of the ink valve accommodation chamber  58  can be absorbed and retained in the ink buffer chamber  80  and the path  82 , thereby preventing the ink from flowing back into the ink valve accommodation chamber  58 . 
     As in the first embodiment, when the ink needle  111  is inserted into the through-hole  73  upon installing the ink cartridge  130  into the cartridge case  110 , the valve main body  64  is separated from the sealing member  65  against the biasing force of the compression spring  63 . The ink needle  111  thus enters into the ink valve accommodation chamber  58 . 
     At this time, an amount of space within the ink valve accommodation chamber  58  capable of accommodating ink therein is reduced by an amount equal to the volume of the inserted ink needle  111 . As a result, the pressure (the ink pressure and/or the air pressure) within the ink valve accommodation chamber  58  increases. Due to the rise in the internal pressure of the ink valve accommodation chamber  58 , the valve member  61  elastically deforms such that the hemispherical section  69  closes the ink-flow passage  59 , preventing the ink from flowing into the ink chamber  36  from the ink valve accommodation chamber  58 . 
     Concurrently, the increase in the internal pressure of the ink valve accommodation chamber  58  causes the ink to flow out of the ink valve accommodation chamber  58  toward the ink buffer chamber  80  via the path  82 . The ink flowed out of the ink valve accommodation chamber  58  is, however, absorbed by the ink absorbing member  83  and retained therein. Also, the film  33  (partially constituting walls of the ink buffer chamber  80  and the path  82 ) can expand (elastically deform) outward so as to enlarge a volume of a space within the path  82  and the ink buffer chamber  80  into which the ink can flow from the ink valve accommodation chamber  58 . As a result, the increased internal pressure of the ink valve accommodation chamber  58  returns to the normal level. The second embodiment can thus achieve technical effects the same as those of the first embodiment. 
     Further, the deformable wall of the ink buffer chamber  80  (the wall made of the film  33 ) is positioned above the ink chamber  36  in the upright posture. In other words, a portion of the ink buffer chamber  80  is disposed above a liquid surface of the liquid accommodated in the ink chamber  36 . Therefore, within the ink buffer chamber  80 , the film  33  is subject to less pressure from the ink. The change in the internal pressure of the ink valve accommodation chamber  58  can impose a greater impact on the deformation of the film  33 . 
     While the invention has been described in detail with reference to the embodiments thereof, it would be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention. 
     For example, instead of the ink absorbing member  83  provided within the ink buffer chamber  80  and the path  82  in the second embodiment, a check valve may be provided within the path  82 . Such check valve serves to allow ink to flow from the ink valve accommodation chamber  58  to the ink buffer chamber  80 , but also to restrict ink from flowing into the ink valve accommodation chamber  58  from the ink buffer chamber  80 .