Patent Publication Number: US-8109615-B2

Title: Ink cartridges

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority from Japanese Patent Application No. JP-2007-225271, which was filed on Aug. 31, 2007, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to ink cartridges. In particular, the present invention is directed towards ink cartridges which comprise a movable member configured to rotate with respect to a shaft positioned in an ink chamber of the ink cartridge. 
     2. Description of Related Art 
     A known recording apparatus is configured to detect when an amount of ink within a known ink cartridge is less than a sufficient amount of ink. For example, the ink cartridge includes an arm configured to rotate with respect to a shaft. The rotatable arm is configured to have a float which is positioned at a first end of the arm, and a blocking member which is positioned at a second end of the arm and is configured to move in an opposite direction with respect to the float based on an amount of ink in the ink cartridge. Moreover, the known recording apparatus may include an optical sensor. When there is a sufficient amount of ink within the ink cartridge, the blocking member is positioned below the optical sensor, and light emitted by the optical sensor is not blocked by the blocking member. Nevertheless, as the ink within the ink cartridge is consumed by the recording apparatus, the surface of the ink within the ink cartridge moves downwards, the float moves downwards, and the blocking member moves upwards. When the amount of ink within the ink cartridge reaches an insufficient amount of ink, the blocking member blocks the light from the optical sensor, and the printer determines that there is an insufficient amount of ink within the ink cartridge. 
     In another known ink cartridge the pressure within the ink chamber is reduced, or the ink cartridge is packaged in a reduced pressure packaging arrangement to prevent gas from dissolving in the ink. In this known ink cartridge, the shaft in the ink chamber may be deformed due to the pressure differential between an interior of the ink cartridge and an exterior of the ink cartridge. When the shaft is deformed, the rotatable arm may not rotate smoothly, which may decrease the accuracy of determining whether there is a sufficient amount of ink in the ink cartridge. 
     It is possible to increase the rigidity of the ink cartridge, e.g., by including metal in the frame or the like. Nevertheless, although increasing the rigidity of the ink cartridge may decrease a likelihood that the shaft will be deformed, such an increase in rigidity may increase the size of the ink cartridge, e.g., the thickness and the width of the ink cartridge, the weight of the ink cartridge, and the cost of the ink cartridge. 
     SUMMARY OF THE INVENTION 
     Therefore, a need has arisen for ink cartridges which overcome these and other shortcomings of the related art. A technical advantage of the present invention is that a shaft of a movable member, e.g., an arm, may not be deformed by a force applied due to a pressure differential between an interior of the ink cartridge and an exterior of the ink cartridge 
     According to an embodiment of the present invention, an ink cartridge comprises a frame, a first wall comprising a film connected to the frame, and a second wall opposite the first wall. The frame, the first wall, and the second wall define an ink chamber therein, and the ink chamber is configured to store ink therein. The ink cartridge also comprises a movable member positioned within the ink chamber, and a shaft extending between the first wall and the second wall. The movable member is configured to pivot about the shaft. Moreover, the frame comprises a first material, and the shaft comprises a second material which is different than the first material. A rigidity of the second material is greater than a rigidity for the first material. 
     Other objects, features, and advantages of embodiments of the present invention will be apparent to persons of ordinary skill in the art from the following description of preferred embodiments with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       For a more complete understanding of the present invention, the needs satisfied thereby, and the objects, features, and advantages thereof, reference now is made to the following description taken in connection with the accompanying drawings. 
         FIGS. 1(A) and 1(B)  are a perspective view of a front side and a rear side, respectively, of an ink cartridge, according to the embodiment of the present invention. 
         FIG. 2  is an exploded, perspective view of the ink cartridge of  FIGS. 1(A) and 1(B) . 
         FIG. 3  is a side view of the ink cartridge of  FIGS. 1(A) and 1(B) . 
         FIG. 4  is an enlarged, perspective view of an ink container, according to an embodiment of the present invention. 
         FIG. 5  is a side view of the ink container of  FIG. 4 . 
         FIG. 6  is an exploded, perspective view of the ink container of  FIG. 4 . 
         FIG. 7  is a perspective view of an arm, according to an embodiment of the present 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Embodiments of the present invention and their features and technical advantages may be understood by referring to  FIGS. 1-7 , like numerals being used for like corresponding portions in the various drawings. 
     Referring to  FIG. 1 , an ink cartridge  10  may be configured to be removably mounted to an ink jet recording apparatus (not shown), such as an ink jet printer. Specifically, ink cartridge  10  may be mounted in a cartridge storage section (not shown) of the recording apparatus when ink cartridge  10  is inserted in a direction of insertion  30 . 
     The ink cartridge  10  may have a substantially flat hexahedron shape, e.g., a substantially rectangular parallelepiped shape, and may be more narrow in a widthwise direction, as indicated by an arrow  31 , than in a height direction, as indicated by an arrow  32 , and a depth direction, as indicated by an arrow  33 . Referring to  FIGS. 1(A)-2 , the ink cartridge  10  may comprise an ink container  20 , a case, e.g., a housing  26 , a movable member, e.g., a slider  27 , and a pair of coil springs  23  and  24 , in which the housing  26  and the slider  27  may form an outer shell of the ink cartridge  10 . The ink container  20  may comprise a frame  50 , an air communication valve  80 , and an ink supply valve  90 . 
     The housing  26  may be configured to protect the ink container  20 . For example, each portion of the ink container  20  other than a front surface  41  may be covered by the housing  26 . The housing  26  may comprise a first cover  21  and a second cover  22  configured to enclose the ink container  20 . The first cover  21  may be attached to a right side surface  46  of the ink container  20  via a plurality of engaging claws  12  positioned on the inner surface of the first cover  21 , which engage engaging grooves  13  positioned on the ink container  20 . Accordingly the right side surface  46  of the ink container  20  is covered by the first cover  21 . Similarly, the second cover  22  is attached to a left side surface  45  of the ink container  20 , such that the left side surface  45  of the ink container  20  is covered by the second cover  22 . The covers  21  and  22  may have a shape which allows covers  21  and  22  to avoid interfering with the frame  50 , the air communication valve  80 , and the ink supply valve  90 . 
     The slider  27  may be configured to protect the air communication valve  80  and the ink supply valve  90 . The slider  27  may be removably attached to the ink container  20 , and an inner surface of the slider  27  may contact the coil springs  23  and  24 . The coil spring  23  may be mounted to a spring receiver  23 A formed at the upper portion of the front surface  41  of the ink container  20 , the coil spring  24  may be mounted to a spring receiver  24 A formed at the bottom portion of the front surface  41 , and the engaging claws  15  and  16  may engage a pair of engaging grooves  17  and  18 , respectively, positioned on the slider  27 , such that a front portion  28  of the housing  26  is covered by the slider  27 . 
     The slider  27  may be configured to slide in the depth direction along the front portion  28  of the housing  26 . Referring to  FIGS. 3(A) and 3(B) , slider  27  may be configured to move between a first position, as shown in  FIG. 3(B) , and a second position, as shown in  FIG. 3(A) . When the slider  27  is in the first position, the slider  27  may be positioned further from the front surface  41  than when the slider  27  is in the second position. When the slider  27  is in the second position, the air intake valve  80  and the ink supply valve  90  may be exposed to the outside via a pair of openings formed in the slider  27 , when the slider  27  is in the first position, the slider  27  may enclose the air communication valve  80  and the ink supply valve  90 . 
     Referring to  FIGS. 4-7 , the ink container  20  may have substantially the same contour and shape as the ink cartridge  10 . When the ink cartridge  10  is mounted to a cartridge storage section (not shown) of the recording apparatus, the cartridge storage section may receive the ink container  20  with the slider  27  in the second position. In this embodiment, the ink container  20  may comprise front surface  41 , a rear surface  42  opposite the front surface  41 , an upper surface  43 , a lower surface  44  opposite the upper surface  43 , a left side surface  45 , and a right side surface  46  opposite the left side surface  45 , such that surfaces  41 - 46  define an enclosure therein. An area of surfaces  45  and  46  may be greater than an area of each of surfaces  41 - 44 . 
     The ink container  20  may comprise frame  50 , an arm  70 , a supporting block  170 , a spring member  150 , the air communication valve  80 , the ink supply valve  90 , and at least one film  65 , e.g., a pair of films  65 . The frame  50  may be a housing of the ink container  20  which defines surfaces  41 - 46 . The frame  50  may comprise a translucent resin, e.g., a transparent resin, and may be formed by injection molding. For example, the frame  50  may comprise polypropylene, polyacetal, nylon, or the like, or any combinations thereof. 
     The frame  50  may comprise an outer peripheral wall  51  and a plurality of inner walls  52 . The inner walls  52  are arranged inside the outer peripheral wall  51 . The outer peripheral wall  51  and the inner walls  52  may be integral with the frame  50 . The outer peripheral wall  51  and the inner walls  52  may extend from the left side surface  45  to the right side surface  46  of the ink container  20 . The outer peripheral wall  51  may be disposed in an annular shape along the front surface  41 , the upper surface  43 , the rear surface  42  and the lower surface  44  to define a space in the interior thereof. Accordingly, an opening  57  may be positioned on each of the left side surface  45  and the right side surface  46  of the frame  50 . 
     The pair of films  65 , e.g., translucent films, may be connected to, e.g., adhered to the left side surface  45  and the right side surface  46 , respectively, of the frame  50  via an adhesion method, e.g., a thermal adhesion method. More specifically, the films  65  are adhered to both end portions of the outer peripheral wall  51  in the widthwise direction  31 . Accordingly, the openings  57  are covered by the films  65 , and a space surrounded by the outer peripheral wall  51  and the films  65  is defined as an ink chamber  100 . Alternatively, a box-shaped frame which is opened on one side only may be employed instead of the frame  50 . In this case, the ink chamber  100  is defined by the film  65  adhered on the opened side of the box shaped frame. 
     The inner walls  52  may be surrounded by the outer peripheral wall  51 . The frame  50  may comprise a partitioning panel  53  which partitions an upper space of the ink chamber  100  at the center in the widthwise direction  31  integrally with the outer peripheral wall  51 . The inner walls  52  may be integral with the outer peripheral wall  51  or the partitioning panel  53 . The films  65  may be adhered to the inner walls  52  at the both end portions in the widthwise direction  31 . Accordingly, inward deformation of the films  65  may be prevented or suppressed. Moreover, although the first cover  21  and the second cover  22  may deform toward the ink container  20 , deformation of the first cover  21  and the second cover  22  may be prevented or suppressed by the inner walls  52 . Consequently, the ink container  20  and the films  65  may not be damaged. The lower portion of the ink chamber  100 , e.g., a space  102 , below the partitioning panel  53  may not be partitioned in the widthwise direction  31 . 
     The film  65  may comprise a plurality of synthetic resin films and may have a multilayer structure. For example, the film  65  may have a three-layer structure having a first layer comprising polypropylene, a second layer comprising nylon, and a third layer comprising polyethylene terephthalate laminated, such that the first layer on the side of the ink chamber  100  may comprise the same material as the frame  50 . Alternatively, the films  65  may comprise a pulp, a metal, a natural resin, or the like. 
     A bearing plate  74  may be positioned at the center of the outer peripheral wall  51  in the widthwise direction and may protrude therefrom. The bearing plate  74  may be positioned at the outer peripheral wall  51  adjacent to a corner defined by the front surface  41  and the lower surface  44 . The bearing plate  74  may be positioned at the end portion in the outer peripheral wall  51  on the side of the right side surface  46 , and may protrude therefrom. The bearing plate  74  may have a bearing  67 , e.g., a circular bearing, positioned on the surface thereof on the side of the left side surface  45 . A shaft  77 , e.g., a shaft having a column shape, may be fitted to the bearing  67 , and a shaft opening  78  of the arm  70  may be fitted on the shaft  77 . The other end of the shaft  77  is supported by the supporting block  170 . 
     An ink injection portion  105  may be positioned at the rear surface  42  of the frame  50 . The ink injection portion  105  may have a circular hole formed therethrough, which may allow fluid communicate between the rear surface  42  and the ink chamber  100 . The ink injection portion  105  may be integral with the frame  50  adjacent to the lower end of the rear surface  42 . The ink injection portion  105  communicates with the ink chamber  100 . Ink is injected into the ink chamber  100  through the ink injection portion  105 . 
     The front surface  41  of the frame  50  may have a translucent portion  140  extending therefrom. The translucent portion  140  may be used to detect the amount of ink stored in the ink chamber  100 . The translucent portion  140  may be integral with the frame  50 , and may comprise the same material as the frame  50 . The translucent portion  140  may be irradiated with light by an optical sensor, such as a photo interrupter, attached to the recording apparatus. The optical sensor has a light-emitting element and a light-receiving element. In this embodiment, the side wall  140 B may be irradiated with light emitted from the light-emitting element, and light which passes through the side wall  140 B may be received by the light-receiving element. 
     The translucent portion  140  may protrude outward from a portion of the front surface  41  adjacent to the middle portion thereof. The translucent portion  140  may be defined by five wall surfaces forming a substantially rectangular shape, and the space  142  may correspond to an interior thereof, and may have a hollow rectangular box shape. For example, the translucent portion  140  may be defined by a front wall  140 A extending in parallel to the front surface  41 , a pair of side walls  140 B, an upper wall  140 C, and a bottom wall  140 D including. The width of the front wall  140 A may be less than the width of the front surface  41 . Moreover, the space  142  may be in fluid communication with the ink chamber  100 . 
     The air communication valve  80  may be positioned above the translucent portion  140 . The air communication valve  80  may be configured to selectively open and close a through hole  81  to allow fluid communication with the atmosphere positioned on the upper portion of the front surface  41 . The air communication valve  80  may comprise a valve body  87 , a spring  86 , a sealing member  83 , and a cap  85 . The air communication valve  80  may close the through hole  81  when the ink cartridge  10  is not mounted to the recording apparatus, and may open the through hole  81  when mounted to the recording apparatus. As such, the pressure of an air layer in the ink chamber  100  is equalized with the atmospheric pressure. Alternatively, the air communication valve  80  may be replaced by a vinyl adhesive tape or film. 
     The ink supply valve  90  may be positioned below the translucent portion  140 . The ink supply valve  90  may be configured to selectively open and close a through hole  91  to allow ink to be dispensed from an interior of ink chamber  100  to an exterior of ink chamber  100 . The ink supply valve  90  may comprise a valve body  97 , a spring  96 , a spring receiver  94 , a sealing member  93 , and a cap  95 . The ink supply valve  90  may close the through hole  91  when the ink cartridge  10  is not mounted to the recording apparatus, and may open the through hole  91  when the ink cartridge  10  is mounted to the recording apparatus and an ink needle (not shown) applies a force to the ink supply valve  90 , such that ink in the ink chamber  100  may be dispensed from the ink chamber  100  to the recording apparatus through the ink needle. 
     The arm  70  may be used to determine the amount of ink stored in the ink chamber  100  is greater than a predetermined amount of ink. The arm  70  may comprise an indicator portion  72  which may be positioned at a first end of the arm  70 . The indicator portion  72  may be configured to be positioned within the inner space  142  or outside the inner space  142  based on the amount of ink in the ink chamber  100 . The arm  70  also may comprise a float portion  73  positioned at a second end of the arm  70 . 
     The arm  70  may have a shaft hole  78  formed therethrough at substantially a center thereof. The shaft  77  may be inserted into the shaft hole  78 . The shaft  77  may be configured to rotatably support the arm  70 , and may be supported by the bearing  67  positioned on the bearing plate  74  at a first end thereof, and by the supporting block  170  at second end thereof. The arm  70  may be rotatably supported by the shaft  77  to be pivotable in the first direction and the second direction, which is perpendicular to the widthwise direction. The shaft  77  may be separate from or integral with the arm  70 . 
     The front surface  41  of the frame  50  may have a translucent portion  140  extending therefrom. The translucent portion  140  may be used to detect the amount of ink stored in the ink chamber  100 . The translucent portion  140  may be integral with the frame  50 , and may comprise the same material as the frame  50 . The translucent portion  140  may be irradiated with light by an optical sensor, such as a photo interrupter, attached to the recording apparatus. The optical sensor has a light-emitting element and a light-receiving element. In this embodiment, the side wall  140 B may be irradiated with light emitted from the light-emitting element, and light which passes through the side wall  140 B may be received by the light-receiving element. 
     The translucent portion  140  may protrude outward from a portion of the front surface  41  adjacent to the middle portion thereof. The translucent portion  140  may be defined by five wall surfaces forming a substantially rectangular shape, and the space  142  may correspond to an interior thereof, and may have a hollow rectangular box shape. For example, the translucent portion  140  may be defined by a front wall  140 A extending in parallel to the front surface  41 , a pair of side walls  140 B, an upper wall  140 C, and a bottom wall  140 D including. The width of the front wall  140 A may be less than the width of the front surface  41 . Moreover, the space  142  may be in fluid communication with the ink chamber  100 . 
     The air communication valve  80  may be positioned above the translucent portion  140 . The air communication valve  80  may be configured to selectively open and close a through hole  81  to allow fluid communication with the atmosphere positioned on the upper portion of the front surface  41 . The air communication valve  80  may comprise a valve body  87 , a spring  86 , a sealing member  83 , and a cap  85 . The air communication valve  80  may close the through hole  81  when the ink cartridge  10  is not mounted to the recording apparatus, and may open the through hole  81  when mounted to the recording apparatus. As such, the pressure of an air layer in the ink chamber  100  is equalized with the atmospheric pressure. Alternatively, the air communication valve  80  may be replaced by a vinyl adhesive tape or film. 
     The ink supply valve  90  may be positioned below the translucent portion  140 . The ink supply valve  90  may be configured to selectively open and close a through hole  91  to allow ink to be dispensed from an interior of ink chamber  100  to an exterior of ink chamber  100 . The ink supply valve  90  may comprise a valve body  97 , a spring  96 , a spring receiver  94 , a sealing member  93 , and a cap  95 . The ink supply valve  90  may close the through hole  91  when the ink cartridge  10  is not mounted to the recording apparatus, and may open the through hole  91  when the ink cartridge  10  is mounted to the recording apparatus and an ink needle (not shown) applies a force to the ink supply valve  90 , such that ink in the ink chamber  100  may be dispensed from the ink chamber  100  to the recording apparatus through the ink needle. 
     The arm  70  may be used to determine the amount of ink stored in the ink chamber  100  is greater than a predetermined amount of ink. The arm  70  may comprise an indicator portion  72  which may be positioned at a first end of the arm  70 . The indicator portion  72  may be configured to be positioned within the inner space  142  or outside the inner space  142  based on the amount of ink in the ink chamber  100 . The arm  70  also may comprise a float portion  73  positioned at a second end of the arm  70 . 
     The arm  70  may have a shaft hole  78  formed therethrough at substantially a center thereof. The shaft  77  may be inserted into the shaft hole  78 . The shaft  77  may be configured to rotatably support the arm  70 , and may be supported by the bearing  67  positioned on the bearing plate  74  at a first end thereof, and by the supporting block  170  at second end thereof. The arm  70  may be rotatably supported by the shaft  77  to be pivotable in the first direction and the second direction, which is perpendicular to the widthwise direction. The shaft  77  may be separate from or integral with the arm  70 . 
     The interior of the float portion  73  may be hollow, and may float on ink. Alternatively, the float portion  73  may have a specific gravity which is less than the specific gravity of ink. Therefore, the float portion  73  may be displaced upward when a level of the ink in the chamber  100  is reduced to be lower than a predetermined ink level, and the arm  70  rotates in accordance with the movement of the float portion  73 . In this embodiment, the float portion  73  may be configured to allow a second portion  76  from the shaft hole  78  to the float portion  73  float in the ink. 
     The indicator portion  72  may be configured to indicate whether the amount of ink remaining in the ink chamber  100  is less than a sufficient amount of ink. When the arm  70  is rotated clockwise as shown in  FIG. 5 , the indicator portion  72  moves into the space  142  of the translucent portion  140 . The indicator portion  72  which may contact the inner surface of the bottom wall  140 D of the translucent portion  140  to prevent the further rotation thereof, and to position the arm  70  in a first position. When the arm  70  is rotated counterclockwise in  FIG. 5 , the indicator portion  72  moves away from the bottom wall  140 D toward a second position. 
     In this embodiment, the second portion  76  may have a weight which is greater than a weight of a first portion  75  extending from the shaft hole  78  toward the indicator portion  72 , such that in the air, the second portion  76  is heavier than the first portion  75 . Consequently, when the amount of ink within the ink chamber  100  is relatively low, the arm  70  rotates counterclockwise in  FIG. 5  about the shaft  77 , and the indicator portion  72  moves out of the space  142  of the translucent portion  140  to indicate that the amount of ink in the ink chamber  100  is less than a sufficient amount of ink. 
     When the float portion  73  is positioned in the ink, a buoyancy is generated at the float portion  73 , such that the arm  70  rotates clockwise in  FIG. 5  about the shaft  77 , and the indicator portion  72  moves into the space  142  of the translucent portion  140  and is positioned at the first position, which indicates that the amount of ink in the ink chamber  100  is greater than the predetermined amount of ink. Alternatively, the  70  may be replaced by a floating member (not shown) to provide an indication as to whether the amount of ink in the ink chamber is greater than a sufficient amount of ink. 
     The spring member  150  may be attached around the arm  70 . The spring member  150  may be fabricated by bending a linear steel member, such as a wire or a line. The spring member  150  may comprise a pair of end portions  151  and  152 , a pair of protecting portions  153  and  154 , and a connecting portion  155 . The spring member  150  may be fixed to the frame  50  by engaging the connecting portion  155  with a hook  131  formed on the frame  50 , and inserting the end portions  151  and  152  into a hole (not shown) formed in the bearing plate  74  and a hole  183  formed in the supporting block  170 , respectively. 
     The spring member  150  may surround the float portion  73  of the arm  70 . For example, the protecting portion  153  may be positioned on the side of the left side surface  45  of the frame  50 , and the protecting portion  154  may be positioned on the side of the right side surface  46 , such that the both sides of the float portion  73  are surrounded by the protecting portions  153  and  154 . Because the protecting portions  153  and  154  may be bent into a substantially V-shape, the protecting portions  153  and  154  may be positioned both sides of the float portions  73  independent of the position of the float portion  73  which is configured to move within the ink chamber  100  based on the amount of ink in the ink chamber  100 . 
     The protecting portions  153  and  154  may be resiliently deformable. Therefore, when the films  65  receive the external force are deformed toward the ink chamber  100 , the protecting portions  153  and  154  deform resiliently toward the float portion  73  together with the films  65  by an external force. Nevertheless, when the external force is damped, those portions of the films  65  which deformed toward the ink chamber  100  are urged outward and away from the float portion  73  by resilient restoration. 
     A method of filling the ink container  20  ink, and a method of manufacturing the ink container  20 , will now be described. The method of manufacturing the ink container may comprise a first step for injecting ink into the ink chamber  100 , and a second step for decreasing the pressure inside ink chamber  100  to be less than the atmospheric pressure. The arm  70 , the shaft  77 , the spring member  150 , the supporting block  170 , the air communication valve  80 , the ink supply valve  90  may be assembled to the frame  50 , and the films  65  may be adhered to the left side surface  45  and the right side surface  46  of the frame  50 , respectively. 
     The ink chamber  100  may comprise the ink injection portion  105  for injecting ink, and a needle (not shown) or the like for injecting ink may be connected to the ink injection portion  105  to inject a predetermined amount of ink into the ink chamber  100 . Prior to the first step, or together with the first step, the second step may be implemented. For example, air in the ink chamber  100  may be reduced and discharged to reduce the pressure in the ink chamber  100 , ink then may be injected into the ink chamber  100  through the ink injection portion  105  using the pressure differential between the interior and the exterior of the ink chamber  100 . This method of injecting ink may be referred to as a pressure-reducing injection method or a vacuum injection method. When the pressure in the ink chamber  100  is reduced, dissolution of air into the ink may be prevented or substantially prevented, and generation of air bubbles in the ink chamber  100  may be prevented or substantially prevented. 
     After the ink is injected, the air communication valve  80  is closed, and the pressure of an air layer in the ink chamber  100  is maintained at a pressure which is less than the atmospheric pressure. Therefore, the films  65  deform toward the ink chamber  100  by the pressure differential between the interior and the exterior of the ink chamber  100 . The housing  26  and the slider  27  are assembled to the ink container  20 , such that the ink cartridge  10  is completed. The ink cartridge  10  then may be positioned in a bag-shaped package material and packed with air in the package material discharged, as needed. 
     The external force caused by such a pressure reduction also may act on the shaft  77 . Nevertheless, because the shaft  77  may comprise stainless steel, the compression strength in the axial direction may be greater than the frame  50 , and consequently, is not deformed by the external force which is applied to the films  65 . Because the bearing plate  74  and the supporting block  170  disposed at the both ends of the shaft  77  support the respective films  65  with planes, the films  65  are prevented from deforming toward the space  102  or the arm  70 . Consequently, the arm  70  rotates smoothly in the ink chamber  100 , and accurate detection of the amount of ink is achieved. 
     The ink cartridge  10  is removed from the package material, and is mounted to the cartridge storage section provided in the recording apparatus. When the ink cartridge is mounted to the recording apparatus, the air communication valve  80  is opened. Consequently, the air layer in the ink chamber  100  is drawn into the atmosphere, and the external force which deforms the films  65  is faded out. 
     When ink in the ink container  20  is consumed, ink may be refilled in the ink container  20 . When refilling ink, the second step described above may be omitted. When ink is disappeared from the ink chamber  100 , the pressure of the ink with respect to the films  65  is faded out, and hence the films  65  may deform toward the ink chamber  100 . Nevertheless, because the films  65  are supported by the shaft  77 , the bearing plate  74  and the supporting block  170 , the films  65  may not deflect toward the space  102 . Consequently, reduction of the capacity of the ink chamber  100  due to the deformation of the films  65  may be avoided, and the ink chamber  100  readily may be refilled with ink. 
     Because the peripheral surface of the shaft  77  is smooth, the rotation of the arm  70  is also smooth, and further accurate detection of the amount of ink is achieved. 
     While the invention has been described in connection with exemplary embodiments, it will be understood by those skilled in the art that other variations and modifications of the exemplary embodiments described above may be made without departing from the scope of the invention. Other embodiments will be apparent to those skilled in the art from a consideration of the specification or practice of the invention disclosed herein. It is intended that the specification and the described examples are considered merely as exemplary of the invention, with the true scope of the invention being indicated by the flowing claims.