Patent Publication Number: US-2009237426-A1

Title: Liquid container and liquid consuming apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application relates to and claims priority from Japanese Patent Application No. 2008-075582, filed on Mar. 24, 2008 and Japanese Patent Application No. 2009-43433, filed on Feb. 26, 2009, the entire disclosure of which is incorporated by reference. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a liquid container and to a liquid consuming apparatus. 
     2. Description of the Related Art 
     As one example of a conventional liquid container, the liquid container disclosed in Patent Citation 1 has a pressurization chamber (3) into which a pressurization fluid is introduced and pressurized; a liquid storage portion (7) adapted to be pressurized by the pressurization fluid and to expel liquid stored therein; and a liquid sensing device ( 11 ) used to sense the amount of stored liquid in the liquid storage portion ( 7 ). The liquid sensing device ( 11 ) is disposed inside the pressurization chamber ( 3 ), and has a liquid sensing chamber ( 21 ) having a liquid inlet ( 11   a ) that communicates with the liquid storage portion ( 7 ) and a liquid outlet ( 11   b ) that communicates with a liquid feed port ( 9 ) for feeding liquid to an external liquid consuming apparatus; a displaceable member ( 27 ) that is moveably actuated by the stored amount of liquid in the liquid storage portion ( 7 ); and sensing means adapted to sense the displacement of the displaceable member ( 27 ) to a prescribed location. 
     According to this liquid container, the frequency with which the internal capacity of the liquid sensing chamber experiences a large degree of deformation from maximum to minimum capacity will be once each time that the liquid in the liquid storage portion is exhausted. Consequently, in contrast to a receptacle having a liquid sensing device disposed to the outside of the pressurization chamber, the flexible walls of the liquid sensing chamber will not experience repeated frequent high levels of deformation, so materials of lower durability and cost can be used for the flexible walls of the liquid sensing chamber, thus contributing to lower cost through reduced cost of the flexible walls liquid sensing device used to sense the stored amount of liquid. 
     However, since this liquid container requires a pressurization chamber ( 3 ) into which the pressurization fluid is introduced and pressurized, pressurization fluid intake means, i.e. pressurization means, will be necessary. 
     Patent Citation 2 discloses an ink cartridge having a sensor chamber and an ink chamber, with a check valve disposed between the sensor chamber and a liquid intake. However, as this is also a pressurized system, pressurization means will be necessary. 
     Patent Citation 3 discloses an ink cartridge having a diaphragm pump ( 26 ) and an ink chamber ( 24 ), with a check valve ( 64 ) for the pump mechanism disposed between the diaphragm pump ( 26 ) and the ink chamber ( 24 ). However, in this design the ink cartridge is furnished with a diaphragm pump ( 26 ) adapted to operate numerous times, and since a diaphragm pump ( 26 ) adapted to operate numerous times must of necessity be more expensive owing to durability requirements, the cartridge will inevitably be more expensive as well. 
     Patent Citation 4 discloses an ink cartridge having a check valve disposed between an intake and an ink chamber. However, this ink cartridge lacks remaining liquid sensing means. 
     Patent Citation 1: Japanese Unexamined Patent Publication 2007-210330 
     Patent Citation 2: Japanese Unexamined Patent Publication 2004-351871 
     Patent Citation 3: Japanese Unexamined Patent Publication 09-164698 
     Patent Citation 4: Japanese Unexamined Patent Publication 2002-192739 
     SUMMARY 
     It is accordingly one object of the present invention to provide a liquid container affording fewer parts and lower cost, despite being provided with means for sensing its own remaining amount of liquid. A further object is to provide a liquid consuming apparatus adapted to use this liquid container. 
     The liquid container according to a first mode of the present invention resides in a liquid container comprising: a liquid storage portion adapted to store a liquid for feeding to a liquid consuming apparatus unit and composed at least in part of a flexible member; a liquid feed port connected to the liquid consuming apparatus unit and adapted to feed liquid stored in the liquid storage portion to the liquid consuming apparatus unit; and a liquid sensing device adapted to sense remaining liquid amount inside the liquid storage portion; wherein the liquid sensing device includes: a liquid sensing chamber having a liquid inlet that communicates with the liquid storage portion and a liquid outlet that communicates with the liquid feed port; a flexible portion defining one face of the liquid sensing chamber and adapted to deform in response to the amount of liquid inside the liquid sensing chamber; a displaceable member housed within the liquid sensing chamber in manner permitting displacement thereof actuated by deformation of flexible portion; sensing means adapted to sense displacement of the displaceable member to a prescribed location; and an bias force member adapted to urge the displaceable member in a direction away from the prescribed location; and wherein the container satisfies the relationship Pf&lt;Ps&lt;Pe where Ps denotes pressure arising through biasing force biasing the displaceable member in a direction away from the prescribed location by the bias force member, Pf denotes the absolute value of negative pressure arising inside the liquid sensing chamber when liquid equal to or greater than a prescribed amount is present in the liquid storage portion; and Pe denotes the absolute value of negative pressure arising inside the liquid sensing chamber when the amount of liquid in the liquid storage portion is less than the prescribed amount. 
     According to this liquid container, because the magnitude of pressure Ps arising through biasing force by the bias force member lies within the range Pf&lt;Ps&lt;Pe, when liquid equal to or greater than a prescribed amount is present in the liquid storage portion, the pressure Ps arising through biasing force biasing the displaceable member in a direction away from the prescribed location by the bias force member will exceed the absolute value Pf of negative pressure arising inside the liquid sensing chamber as liquid is fed to the liquid consuming apparatus unit from the liquid feed port. Consequently, the displaceable member will move away from the prescribed location. Thus, the sensing means will be able to sense that liquid equal to or greater than a prescribed amount is present in the liquid storage portion. 
     On the other hand, as the amount of liquid in the liquid storage portion goes below the prescribed amount in association with feed of liquid from the liquid feed port, the pressure Ps arising through biasing force biasing the displaceable member in a direction away from the prescribed location by the bias force member will fall below the absolute value Pe of negative pressure arising inside the liquid sensing chamber as liquid is fed to the liquid consuming apparatus unit from the liquid feed port. Consequently, the displaceable member will move to the prescribed location. Thus, the sensing means will be able to sense that the amount of liquid in the liquid storage portion has fallen to less than the prescribed amount. 
     In another possible arrangement, displacement of the displaceable member will occur one time before the liquid in the liquid storage portion is exhausted. Moreover, there is no need for pressurizing means for pressurizing the perimeter of the liquid storage portion to bring about displacement of the displaceable member. That is, according to this liquid container, liquid can be supplied to the liquid consuming apparatus unit through a head differential or suction force on the liquid consuming apparatus unit side, thus making possible cost reductions while still providing remaining liquid sensing means. 
     The liquid container according to a second mode of the present invention resides in a liquid container comprising: a liquid storage portion adapted to store a liquid for feeding to a liquid consuming apparatus unit and composed at least in part of a flexible member; a liquid feed port connected to the liquid consuming apparatus unit and adapted to feed liquid stored in the liquid storage portion to the liquid consuming apparatus unit; and a liquid sensing device adapted to sense the remaining amount of liquid inside the liquid storage portion; wherein the liquid sensing device includes: a liquid sensing chamber having a liquid inlet that communicates with the liquid storage portion and a liquid outlet that communicates with the liquid feed port; a flexible portion defining one face of the liquid sensing chamber and adapted to deform in response to the amount of liquid inside the liquid sensing chamber; a displaceable member housed within the liquid sensing chamber and capable of displacement actuated by deformation of flexible portion; sensing means adapted to sense displacement of the displaceable member to a prescribed location; and an bias force member adapted to urge the displaceable member in a direction away from the prescribed location; and wherein a check valve adapted to block backflow of liquid from the liquid feed port towards the liquid sensing chamber is disposed between the liquid feed port and the liquid outlet from the liquid sensing chamber. 
     In the liquid container of the second mode of the present invention as well, when liquid equal to or greater than a prescribed amount is present in the liquid storage portion, the displaceable member will undergo displacement away from the prescribed location by the bias force member; and when the amount of liquid falls to less than the prescribed amount, the displaceable member will undergo displacement to the prescribed location in opposition to the biasing force of the bias force member. Thus, the sensing means will be able to sense that the amount of liquid in the liquid storage portion has fallen to less than the prescribed amount. 
     In particular, according to the second mode of the present invention, a check valve for blocking backflow of liquid from the liquid feed port towards the liquid sensing chamber is disposed between the liquid feed port and the liquid outlet from the liquid sensing chamber. Thus, if for some reason, such as entrainment through a liquid ejection nozzle of the liquid consuming apparatus unit, an air bubble should become entrained into the liquid flow channel on the downstream side from the liquid intake portion of the liquid consuming apparatus (the upstream side in relation to the direction of liquid feed), the bubble will be prevented from infiltrating the liquid sensing chamber. Since the bubble is prevented from infiltrating the liquid sensing chamber, sensor error will not occur. 
     The risk of such backflow will be greater in a pressurized system in which liquid is delivered by pressurizing the perimeter of the liquid storage portion, than it is in a non-pressurized system in which liquid is delivered through suction or a head differential, for example. The reason is that in a pressurized system, biasing force of the bias force member will act in a direction so as to push out backflow, whereas in a non-pressurized system biasing force of the bias force member will act in a direction so as to draw in backflow. 
     In another possible construction according to the first mode or second mode, the bias force member is composed of a spring interposed between the displaceable member and the liquid sensing chamber, between a first face of the liquid sensing chamber and the face opposing the first face; and the displaceable member and the first face of the liquid sensing chamber are disposed in abutment without being attached. With this arrangement, since there is no need for the displaceable member and the first face of the liquid sensing chamber to be attached, the first face of the liquid sensing chamber will not experience unwanted stress. 
     The liquid consuming apparatus according to a third mode of the present invention comprises a liquid intake portion connected to the liquid feed port of the liquid container having the check valve; a liquid consuming portion; and a diaphragm pump disposed between the liquid intake portion and the liquid consuming portion for the purpose of feeding liquid from the liquid intake portion to the liquid consuming portion and adapted to deliver liquid through application of external force in the direction of expansion of volume thereof from a previous state of having been urged in the direction of reduced volume followed by subsequent release of the external force; wherein pressure acting on the liquid sensing chamber resulting from external force applied in the direction of expansion of volume of the diaphragm pump will be greater than pressure applied to the liquid sensing chamber resulting from biasing force of the bias force member which urges the flexible portion of the liquid sensing chamber. 
     According to this liquid consuming apparatus, because the liquid container has a check valve, liquid can be supplied to the liquid consuming portion by the diaphragm pump, without necessarily having to provide a check valve between the liquid intake portion and the diaphragm pump. The cost of the liquid consuming apparatus can be reduced thereby. 
     Furthermore, according to this liquid consuming apparatus, when external force is applied in the direction of expansion of volume of the diaphragm pump, the decompression level acting on the liquid sensing chamber will exceed the pressure resulting from biasing force of the liquid sensing chamber. If there is sufficient liquid present in the liquid storage portion when the external force is applied, the liquid sensing chamber will experience substantially no change in volume, whereas if the level of liquid in the liquid storage portion is so low that liquid cannot be supplied to the liquid sensing chamber the absolute value of negative pressure of the liquid sensing chamber will exceed the pressure by the biasing force, so the volume will contract. Consequently, owing to the above pressure relationships, it will be possible to utilize volume changes of the liquid sensing chamber to sense the remaining amount of liquid. 
     The liquid consuming apparatus according to a fourth mode of the present invention comprises a liquid consuming apparatus unit and a liquid container attached to the liquid consuming apparatus unit; wherein the liquid container includes a liquid storage portion adapted to store a liquid for feeding to the liquid consuming apparatus unit and composed at least in part of a flexible member, a liquid feed port connected to the liquid consuming apparatus unit and adapted to feed liquid stored in the liquid storage portion to the liquid consuming apparatus unit, and a liquid sensing device adapted to sense the remaining amount of liquid inside the liquid storage portion; the liquid sensing device includes a liquid sensing chamber having a liquid inlet that communicates with the liquid storage portion and a liquid outlet that communicates with the liquid feed port, a flexible portion defining one face of the liquid sensing chamber and adapted to deform in response to the amount of liquid inside the liquid sensing chamber, a displaceable member housed within the liquid sensing chamber and capable of displacement actuated by deformation of flexible portion, sensing means adapted to sense displacement of the displaceable member to a prescribed location, and an bias force member adapted to urge the flexible portion in the direction of expansion of volume of the liquid sensing chamber; the liquid consuming apparatus unit includes a liquid intake portion connected to the liquid feed port of the liquid container, a liquid consuming portion, a diaphragm pump disposed between the liquid intake portion and the liquid consuming portion for the purpose of feeding liquid from the liquid intake portion to the liquid consuming portion and adapted to deliver liquid through application of external force in the direction of expansion of volume thereof from a previous state of having been urged in the direction of reduced volume followed by subsequent release of the external force, and a check valve disposed between the diaphragm pump and the liquid intake portion and adapted to block backflow of liquid from the diaphragm pump towards the liquid intake portion; and wherein pressure acting on the liquid sensing chamber resulting from external force applied in the direction of expansion of volume of the diaphragm pump will be greater than pressure applied to the liquid sensing chamber resulting from biasing force of the bias force member. 
     According to this liquid consuming apparatus, when external force is applied in the direction of expansion of volume of the diaphragm pump, if sufficient liquid is present in the liquid storage portion, the volume of the liquid sensing chamber will remain substantially unchanged; whereas if the level of liquid in the liquid storage portion is so low that liquid cannot be supplied to the liquid sensing chamber the absolute value of negative pressure inside the liquid sensing chamber will exceed the pressure by the bias force member, so the volume of the liquid sensing chamber will contract. Consequently, owing to the above pressure relationships, it will be possible to utilize volume changes of the liquid sensing chamber to sense the remaining amount of liquid. Additionally, a check valve adapted to block backflow of liquid from the liquid feed port towards the liquid sensing chamber is disposed between the liquid feed port and the liquid outlet of the liquid sensing chamber. Thus, if for some reason, such as entrainment through a liquid ejection nozzle of the liquid consuming apparatus unit, an air bubble should become entrained into the liquid flow channel on the downstream side from the liquid intake portion of the liquid consuming apparatus (the upstream side in relation to the direction of liquid feed), the bubble will be prevented from infiltrating the liquid sensing chamber. Since bubbles are prevented from infiltrating the liquid sensing chamber, sensor error will not occur. 
     The liquid consuming apparatus according to a fifth mode of the present invention comprises a liquid consuming apparatus unit and a liquid container attached to the liquid consuming apparatus unit; wherein the liquid container includes a liquid storage portion adapted to store a liquid for feeding to the liquid consuming apparatus unit and composed at least in part of a flexible member, a liquid feed port connected to the liquid consuming apparatus unit and adapted to feed liquid stored in the liquid storage portion to the liquid consuming apparatus unit, and a liquid sensing device adapted to sense the remaining amount of liquid inside the liquid storage portion; the liquid sensing device includes a liquid sensing chamber having a liquid inlet that communicates with the liquid storage portion and a liquid outlet that communicates with the liquid feed port, a flexible portion defining one face of the liquid sensing chamber and adapted to deform in response to the amount of liquid inside the liquid sensing chamber, a displaceable member housed within the liquid sensing chamber and capable of displacement actuated by deformation of flexible portion, sensing means adapted to sense displacement of the displaceable member to a prescribed location, and an bias force member adapted to urge the flexible portion in the direction of expansion of volume of the liquid sensing chamber; the liquid container further includes a check valve disposed between the liquid feed port and the liquid outlet provided to the liquid sensing chamber and adapted to block backflow of liquid from the liquid feed port towards the liquid sensing chamber; the liquid consuming apparatus unit includes a liquid intake portion connected to the liquid feed port of the liquid container, a liquid consuming portion, and a diaphragm pump disposed between the liquid intake portion and the liquid consuming portion for the purpose of feeding liquid from the liquid intake portion to the liquid consuming portion and adapted to deliver liquid through application of external force in the direction of expansion of volume thereof from a previous state of having been urged in the direction of reduced volume followed by subsequent release of the external force; and wherein pressure acting on the liquid sensing chamber resulting from external force applied in the direction of expansion of volume of the diaphragm pump will be greater than pressure applied to the liquid sensing chamber resulting from biasing force of the bias force member. 
     According to this liquid consuming apparatus, when external force is applied in the direction of expansion of volume of the diaphragm pump, if sufficient liquid is present in the liquid storage portion the volume of the liquid sensing chamber will remain substantially unchanged; whereas if the level of liquid in the liquid storage portion is so low that liquid cannot be supplied to the liquid sensing chamber, the absolute value of negative pressure inside the liquid sensing chamber will exceed the pressure by bias force member and the volume of the liquid sensing chamber will contract. Consequently, owing to the above pressure relationships, it will be possible to utilize volume changes of the liquid sensing chamber to sense the remaining amount of liquid. 
     Moreover, because the liquid container has a check valve, liquid can be supplied to the liquid consuming portion by the diaphragm pump without necessarily having to provide a check valve between the liquid intake portion and the diaphragm pump. The cost of the liquid consuming apparatus can be reduced thereby. 
     In another possible arrangement of the liquid consuming apparatus according to the fifth mode of the present invention, an on-off valve is disposed on the liquid flow channel connecting the diaphragm pump and the liquid intake portion. With this arrangement, liquid can be prevented from dripping from the liquid intake portion when the liquid intake portion and the liquid feed port of the liquid container are disconnected. 
     The present invention in a sixth mode provides a liquid container attachable to a liquid consuming apparatus. The liquid container according to the sixth mode comprises a liquid storage portion that stores a liquid, a liquid feed portion that connects with the liquid consuming apparatus and feeds the liquid to the liquid consuming apparatus when the liquid container is attached to the liquid consuming apparatus, a liquid sensing chamber defining portion having a liquid inlet communicating with the liquid storage portion and a liquid outlet communicating with the liquid feed portion and that defines a liquid sensing chamber that fluctuates in volume according to a differential between external atmospheric pressure and internal pressure, a bias force member that exerts a bias force on the liquid sensing chamber from an inner side in a direction of expansion of volume of the liquid sensing chamber, and a sensor that senses if a volume of the liquid sensing chamber is reduced to a prescribed volume value. A pressure of liquid present in the liquid sensing chamber declines as an amount of liquid in the liquid storage portion becomes lower. The bias force is established such that if the amount of liquid in the liquid storage portion is equal to or greater than a prescribed amount, the liquid sensing chamber overcomes the atmospheric pressure to assume a volume exceeding the prescribed volume value, whereas if the amount of liquid in the liquid storage portion is less than the prescribed amount, the liquid sensing chamber yields to the atmospheric pressure to assume a volume equal to or less than the prescribed volume value. Since this arrangement does not require a pressurization device, the number of parts can be minimized, and reduced cost can be achieved. 
     In another possible arrangement of the liquid container according to the sixth mode, the liquid sensing chamber defining portion includes an open chamber portion having the liquid inlet, the liquid outlet, and an opening, and a flexible portion that is formed of flexible material capable of deformation in response to a differential between the atmospheric pressure and the internal pressure and that covers the opening to define the liquid sensing chamber in association with the open chamber portion. With this arrangement, a liquid sensing chamber adapted to undergo deformation in response to a differential between atmospheric pressure received from the outside and pressure received from the inside can be constituted in a simple manner. 
     Yet another possible arrangement of the liquid container according to the sixth mode further comprises a displaceable member housed within the liquid sensing chamber and capable of displacement due to deformation of the flexible portion. The sensor senses if volume of the liquid sensing chamber has dropped to the prescribed volume value by sensing if the displaceable member is displaced to a prescribed location. The bias force member biases the displaceable member in a direction away from the prescribed location. With this arrangement, drop in volume of the liquid sensing chamber to a prescribed volume can be sensed with a simple arrangement by sensing a prescribed location of the displaceable member. 
     In yet another possible arrangement of the liquid container according to the sixth mode, the bias force member is a spring disposed between the displaceable member and an opposing face situated in opposition to the flexible portion in the open chamber portion. The spring is not bonded to the opposing face and the displaceable member, but disposed in abutment with the opposing face and the displaceable member. With this arrangement, since there is no need for the displaceable member and the first face of the liquid sensing chamber to be attached, the first face of the liquid sensing chamber will not experience unwanted stress. 
     In yet another possible arrangement of the liquid container according to the sixth mode, the liquid storage portion is flexible at least in part, whereby the pressure of liquid present in the liquid sensing chamber declines as the amount of liquid in the liquid storage potion becomes lower. With this arrangement, depending on the rigidity of the flexible section of the liquid storage portion, the pressure of liquid present in the liquid sensing chamber will decline as the remaining amount of liquid in the liquid storage portion becomes progressively lower. 
     Yet another possible arrangement of the liquid container according to the sixth mode further comprises a check valve disposed between the liquid feed portion and the liquid outlet, and adapted to block backflow of the liquid from the liquid feed portion towards the liquid sensing chamber. With this arrangement, air bubbles entering from the liquid consuming apparatus for some reason can be prevented from infiltrating into the liquid sensing chamber. As a result, sensor error due to an air bubble infiltrating the sensor portion can be avoided. 
     In yet another possible arrangement of the liquid container according to the sixth mode, the bias force is established such that if the amount of liquid in the liquid storage portion is less than a prescribed value and the liquid is flowing from the liquid storage portion into the liquid consuming apparatus, the liquid sensing chamber yields to the atmospheric pressure to assume a volume equal to or less than the prescribed volume value. The sensing by the sensor is executed while the liquid is flowing in the liquid storage portion. When liquid is flowing through the liquid storage portion, pressure of the liquid in the liquid storage portion will be lower. Consequently, the liquid storage portion will reach a volume equal to less than a prescribed volume value only a single time before the amount of liquid of the liquid storage portion goes below a prescribed value. As a result, the number of times that the liquid storage portion changes in volume can be reduced, so the components that form the liquid storage portion can be less durable. 
     In yet another possible arrangement of the liquid container according to the sixth mode, the bias force is established such that if the amount of liquid in the liquid storage portion is less than a prescribed value, then regardless of whether there is flow of liquid in the liquid storage portion, the liquid sensing chamber yields to the atmospheric pressure to assume volume equal to or less than the prescribed volume value. The sensing by the sensor is executed while the liquid is not flowing in the liquid storage portion. With this arrangement, during periods that the liquid is not flowing in the liquid storage portion, it can be sensed whether the liquid storage portion has reached an amount of liquid equal to or less than a prescribed value. 
     The present invention in a seventh mode provides a liquid consuming system comprising a liquid consuming apparatus and a liquid container attachable to the liquid consuming apparatus. The liquid container includes a liquid storage portion that stores a liquid, a liquid feed portion that connects with the liquid consuming apparatus and feeds the liquid to the liquid consuming apparatus when the liquid container is attached to the liquid consuming apparatus, a liquid sensing chamber defining portion having a liquid inlet communicating with the liquid storage portion and a liquid outlet communicating with the liquid feed portion and that defines a liquid sensing chamber that fluctuates in volume according to a differential between atmospheric pressure received from an outside and pressure received from an inside, a bias force member that exerts a bias force on the liquid sensing chamber from an inner side in a direction of expansion of volume of the liquid sensing chamber, and a sensor that senses a decline in volume of the liquid sensing chamber to a prescribed volume value. A pressure of liquid present in the liquid sensing chamber declines as a amount of liquid in the liquid storage portion becomes lower. The bias force is established such that if the amount of liquid in the liquid storage portion is equal to or greater than a prescribed amount, the liquid sensing chamber overcomes atmospheric pressure to assume a volume exceeding a prescribed volume value, whereas if the amount of liquid in the liquid storage portion is less than a prescribed amount, the liquid sensing chamber yields to atmospheric pressure to assume a volume equal to or less than a prescribed volume value. The liquid consuming apparatus includes a liquid intake portion connected to the liquid feed portion of the liquid container, a liquid consuming portion, and a diaphragm pump disposed between the liquid intake portion and the liquid consuming portion and adapted to deliver the liquid to the liquid consuming portion via the liquid intake portion through application of external force in a direction of expansion of volume thereof from a previous state of having been urged in the direction of reduction of internal volume followed by subsequent release of the external force. Pressure acting on the liquid sensing chamber resulting from the external force is greater than pressure produced by the bias force of the bias force member. This arrangement affords working effects comparable to those of the liquid container according to the sixth mode. Furthermore, when external force is applied in the direction of expansion of volume of the diaphragm pump, the decompression level acting on the liquid sensing chamber will exceed the pressure by bias force member of the liquid sensing chamber. If there is sufficient liquid present in the liquid storage portion when external force is applied, the liquid sensing chamber will experience substantially no change in volume, whereas if the level of liquid in the liquid storage portion is so low that liquid cannot be supplied to the liquid sensing chamber the absolute value of negative pressure of the liquid sensing chamber will exceed the pressure by the biasing force, so the volume will contract. Consequently, owing to the above pressure relationships, it will be possible to utilize volume changes of the liquid sensing chamber to sense the remaining amount of liquid. 
     In another possible arrangement in the liquid consuming system according to the seventh mode, the liquid container further includes a check valve disposed between the liquid feed portion and the liquid outlet, and adapted to block backflow of the liquid from the liquid feed portion towards the liquid sensing chamber. With this arrangement, liquid can be supplied to the liquid consuming portion by the diaphragm pump without necessarily having to provide a check valve between the liquid intake portion and the diaphragm pump. The cost of the liquid consuming apparatus can be reduced thereby. 
     In yet another possible arrangement in the liquid consuming system according to the seventh mode, the liquid consuming apparatus further includes an on-off valve disposed between the diaphragm pump and the liquid intake portion. With this arrangement, liquid can be prevented from dripping from the liquid intake portion when the liquid intake portion and the liquid feed port of the liquid container are disconnected. 
     The above and other objects, characterizing features, aspects and advantages of the invention will be clear from the description of preferred embodiments presented below along with the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a construction drawing depicting an embodiment of a liquid container according to the present invention; 
         FIG. 2  is an illustration of operation when liquid inside a liquid container has been consumed; 
         FIG. 3  is a construction drawing depicting another embodiment of a liquid container according to the present invention; 
         FIG. 4  is an illustration of operation when liquid inside a liquid container has been consumed; 
         FIG. 5  is a schematic diagram depicting an embodiment of a liquid consuming apparatus according to the present invention; 
         FIG. 6  is a drawing illustrating operation of a liquid consuming apparatus; 
         FIG. 7  is a drawing illustrating operation of a liquid consuming apparatus; 
         FIG. 8  is a drawing illustrating operation of a liquid consuming apparatus; and 
         FIG. 9  is a drawing illustrating biasing force by an bias force member in a second embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The preferred embodiments of the present invention will now be described in detail. The embodiments set forth hereinbelow are not intended to unduly limit the particulars of the present invention recited in the appended claims; nor should all of the arrangements described in the embodiments be construed as essential means for solving the problems addressed by the present invention. 
     A. First Embodiment 
     (Liquid Container) 
       FIG. 1  is a construction drawing depicting an embodiment of a liquid container according to the present invention.  FIG. 2  is an illustration of operation when liquid inside a liquid container  7  has been consumed. 
     The liquid container  1  of the present embodiment is an ink cartridge adapted for detachable installation in a cartridge installation portion of an inkjet recording device and designed to supply ink (liquid) to a liquid jetting head (liquid consuming portion) provided on the recording device. 
     This liquid container  1  is furnished with a liquid storage portion  7 , a liquid feed port  9 , and a liquid sensing device  11 . The liquid storage portion  7  contains a liquid that is suctioned out and supplied to the liquid consuming apparatus unit, and is composed at least in part of a flexible member. The liquid feed port  9  is a feed port that is connected to the liquid consuming apparatus unit and that supplies the liquid consuming apparatus unit with the liquid contained in the liquid storage portion  7 . The liquid sensing device  11 , discussed later, is used to sense the remaining amount of liquid in the liquid storage portion  7 . 
     The liquid sensing device  11  is furnished with a liquid sensing chamber  21 , a flexible portion  23 , a displaceable member  27 , sensing means  25 , and an bias force member  29 . The liquid sensing chamber  21  has a liquid inlet  11   a  that communicates with the liquid storage portion  7 , and a liquid outlet  11   b  that communicates with the liquid feed port  9 . The flexible portion  23  defines one wall of the liquid sensing chamber  21  and is deformable according to the amount of liquid inside the liquid sensing chamber  21 . The displaceable member  27  is housed within the liquid sensing chamber  21  so as to be capable of displacement actuated by deformation of flexible portion  23 . The sensing means  25  can sense displacement of the displaceable member  27  to a prescribed location. The bias force member  29  urges the displaceable member  27  in a direction away from the prescribed location. Where Ps denotes pressure arising through biasing force biasing the displaceable member  27  in a direction away from the prescribed location (the direction indicated by arrow Ps) by the bias force member  29 , Pf denotes the absolute value of negative pressure arising inside the liquid sensing chamber  21  through flow of liquid when liquid is delivered from the liquid feed port  9  to the liquid consuming apparatus unit when liquid equal to or greater than a prescribed amount is present in the liquid storage portion  7 , and Pe denotes the absolute value of negative pressure arising inside the liquid sensing chamber  21  when liquid is delivered from the liquid feed port  9  to the liquid consuming apparatus unit when the amount of liquid in the liquid storage portion  7  is less than the prescribed amount (see  FIG. 2 ), the biasing force Ps produced by the bias force member  29  will have magnitude within the range Pf&lt;Ps&lt;Pe. 
     The liquid container  1  has a case  5 ; the liquid storage portion  7  and the liquid sensing device  11  are housed inside this case  5 . The case  5  is a housing of cube shape, and of the six confining walls that define an internal space  3 , the confining wall  5   a  at a first end is perforated by an air vent hole  13 . Where the case  5  has been formed by connecting a plurality of members, if the edges of the members are not sealed together, the interstices between the members will function analogously to the air vent hole  13 , so the air vent hole  13  may not be needed in this case. Typically, it will be acceptable for the pressure of the space inside the case  5  to be equal to atmospheric pressure. 
     The liquid storage portion  7  is a so-called ink pack produced by joining a discharge spout  7   a  of tubular shape adapted to connect with the liquid inlet  11   a  of the liquid sensing device  11 , to one end of a pouch  7   b  that has been constructed by bonding together the edges of aluminum laminate composite films composed of an aluminum layer laminated over a resin film layer. The use of aluminum laminate composite films ensures high gas barrier properties. 
     The liquid feed port  9  perforates the confining wall  5   b  at one end of the case  5 . To the inside of the liquid feed port  9  there are provided an annular sealing member  9   a  for receiving insertion of a liquid feed needle  40  of the liquid consuming apparatus unit and pressing against the outside surface of the liquid feed needle  40  when the liquid container (cartridge)  1  is installed on the liquid consuming apparatus unit; a valve  9   b  adapted to abut the sealing member  9   a  and block off the liquid feed port  9  when the receptacle is not installed on the liquid consuming apparatus unit; and a compression spring  9   c  for biasing the valve  9   b  in a direction so as to press it against the sealing member  9   a.    
     When the liquid container  1  is installed on the liquid consuming apparatus unit (see  FIG. 5 ), the liquid feed needle  40  provided to the liquid consuming apparatus unit will insert into the liquid feed port  9 , and the outside peripheral surface of the liquid feed needle  40  will seal liquidtightly against the inside peripheral surface of the sealing member  9   a.  The distal end of the liquid feed needle  40  will come into abutment against the valve  9   b,  pushing the valve  9   b  to the back and breaking the seal between the valve  9   b  and the sealing member  9   a  so that it will be possible for liquid to be fed into the liquid feed needle  40  from the liquid feed port  9 . 
     The liquid sensing device  11  is furnished with a sensing device case  19 , the flexible portion  23 , an oscillation sensor  25 , the displaceable member  27 , and the bias force member  29 . The sensing device case  19  has a recess space  19   a  connecting with the liquid inlet  11   a  that connects to the discharge spout  7   a  of the liquid storage portion  7  and with the liquid outlet  11   b  that connects to the liquid feed port  9 . The flexible portion  23  is a confining wall that is made of flexible film and that seals off the opening at the top face of the recess space  19   a  to define the liquid sensing chamber (which also serves as a liquid holding chamber)  21 . The oscillation sensor  25  is disposed at the bottom part of the recess space  19   a  where it is employed as the sensing means. The displaceable member  27  is mounted on the inside face of the flexible portion  23  and in opposition to the oscillation sensor  25 . The bias force member  29  is compression-fit between this displaceable member  27  and the bottom of the recess space  19   a  so as to urge the displaceable member  27  and the flexible portion  23  in the direction of expansion of volume of the liquid sensing chamber  21 . In the present embodiment, a torsion spring (compression spring) is employed as the bias force member  29 . 
     The flexible portion  23  functions as a diaphragm for imparting displacement to the displaceable member  22  in response to pressure of liquid supplied to the liquid sensing chamber  21 . The flexible portion  23  has ample flexibility enabling it to sense minute pressure fluctuations of the liquid so as to enhance sensor accuracy. 
     The bias force member  29  is composed of a compression spring of truncated conical shape. The compression spring employed as the bias force member  29  is disposed interposed between the flexible portion  23  which constitutes one face of the liquid sensing chamber, and the bottom face  19   b  of the sensing device case  19  which is the opposed face to this flexible portion face. The flexible portion  23  and the displaceable member  27  are disposed in abutment without being attached. 
     In the sensing device  19 , the liquid inlet  11   a  has been integrally formed in one of the peripheral walls that define the recess space  19   a,  while the liquid outlet  11   b  that communicates with the liquid feed port  9  perforates the peripheral wall that faces this liquid inlet  11   a.  A check valve  15  is disposed in the liquid inlet  11   a,  and serves to block the flow of liquid attempting to backflow from the liquid sensing chamber  21  into the liquid storage portion  7 . 
     As depicted in  FIG. 2 , the oscillation sensor  25  in the liquid sensing device  11  has a base plate  31  adapted to come into intimate contact against the displaceable member  27  when the liquid in the liquid storage portion  7  has been exhausted; a liquid conducting path  33  defined by a recess formed in the base plate  31 ; and a piezoelectric element adapted to apply oscillation to the liquid conducting path  33  and to sense free oscillation thereafter. 
     The oscillation sensor  25  detects whether liquid is present (i.e. the remaining amount of liquid) based on state changes (e.g. change in amplitude or frequency of residual oscillation) of free oscillation, which varies depending on whether the liquid conducting path  33  is closed off by the displaceable member  27 . 
     When the liquid in the liquid storage portion  7  has been exhausted, the absolute value Pe of negative pressure arising inside the liquid sensing chamber  21  due to the liquid inside the liquid sensing chamber  212  having been supplied to the liquid consuming apparatus unit from the liquid feed port  9  will exceed the pressure Ps arising through biasing force by the bias force member  29 , and thus the displaceable member  27  will be pushed downward in opposition to the bias force member  29  and come into intimate contact against the base plate  31 . 
     As noted, the biasing direction of the bias force member  29  is also the direction of expansion of volume of the liquid sensing chamber  21 , and is the opposite direction from the side where the oscillation sensor  25  is located. The liquid conducting path  33  which is formed by the recess in the base plate  31  will be defined within a closed space that with the displaceable member  27  in contact against the base plate  31  is sealed off from the liquid sensing chamber  21  as depicted in  FIG. 2 ; and with the displaceable member  27  separated from the base plate  31  will communicate with the liquid sensing chamber  21  as depicted in  FIG. 1 . 
     In the present embodiment, the location at which the displaceable member  27  comes into contact against the base plate  31  due to a decreasing amount of liquid held in the liquid sensing chamber  21  corresponds to the prescribed location of the displaceable member in the claims. The point in time at which the displaceable member  27  comes into contact against the base plate  31  to render the liquid conducting path  33  a closed space will be set to a condition in which the level of liquid in the liquid storage portion  7  is less than the prescribed amount. 
     In the present embodiment, the liquid sensing device refers to a device that, by installing the liquid container on the liquid consuming apparatus unit, will connect with a sensor circuit or the like provided on the liquid consuming apparatus unit side and make up part of a liquid sensing system in order to be used to sense the amount of stored liquid. 
     (Working Effects of Liquid Container  1 ) 
     According to the liquid container  1  described above, where Ps denotes pressure arising through biasing force biasing the displaceable member  27  in a direction away from the prescribed location by the bias force member  29 , Pf denotes the absolute value of negative pressure arising inside the liquid sensing chamber  21  when liquid is delivered from the liquid feed port  9  to the liquid consuming apparatus unit when liquid equal to or greater than a prescribed amount (an amount sufficient for delivery to the liquid sensing chamber  21 ) is present in the liquid storage portion  7 , and Pe denotes the absolute value of negative pressure arising inside the liquid sensing chamber  21  due to the flow of liquid being fed from the liquid feed port  9  to the liquid consuming apparatus unit when the amount of liquid in the liquid storage portion  7  is less than the prescribed amount, the pressure Ps produced by biasing force of the bias force member  29  will have magnitude within the range Pf&lt;Ps&lt;Pe. Thus, as depicted in  FIG. 1 , when liquid equal to or greater than a prescribed amount is present in the liquid storage portion  7 , the pressure Ps arising through biasing force that urges the displaceable member  27  in a direction away from the prescribed location (in this embodiment, the location at which the displaceable member  27  comes into contact against the base plate  31 ) by the bias force member  29  will be greater than the absolute value Pf of negative pressure arising inside the liquid sensing chamber  21  due to the flow of liquid being fed from the liquid feed port  9  to the liquid consuming apparatus unit. 
     Consequently, the displaceable member  27  will undergo displacement away from the prescribed location. Thus, oscillation sensor  25  will sense that liquid is present in the liquid storage portion  7  in an amount equal to or greater than the prescribed amount. 
     While the pressure Ps produced by biasing force will vary depending on the location of the displaceable member  27 , in the following discussion, it will be assumed to be Ps=+5 kPa for example. While in actual practice reaction force of the flexible portion constituting the diaphragm will come into play as well, this force will be ignored here. The following discussion shall take into consideration pressure Pp resulting from rigidity of the flexible film that defines the liquid storage portion  7 , and the pressure drop Pr produced by fluid flow within the liquid storage portion  7 , caused by the liquid sensing chamber  21  going to negative pressure. 
     When sufficient liquid is present in the liquid storage portion  7  as depicted in  FIG. 1 , pressure Pp resulting from rigidity of the flexible film that defines the liquid storage portion  7  will act so to push out liquid and increase pressure inside the liquid sensing chamber  21 , bringing it to Pp=+0.5 kPa for example. In the absence of flow of liquid in  FIG. 1 , there will be no pressure drop Pr produced by fluid flow within the liquid storage portion  7 . At this point, the sum of pressure inside the liquid sensing chamber  21  will be Ps+Pp=+5.5 kPa; pressure (Pp+Pr) excluding the pressure Ps produced by biasing force will be +0.5 kPa; and negative pressure will not arise (Ps&gt;Pf (where Pf is the absolute value of negative pressure)). Thus, the displaceable member  27  will be pushed upward by the spring  29 . 
     Next, when fluid flow occurs in  FIG. 1 , the pressure drop Pr produced by fluid flow within the liquid storage portion  7  will go to Pr=−0.5 kPa for example. At this point, the sum of pressure inside the liquid sensing chamber  21  will be Ps+Pp+Pr=+5.0 kPa; pressure (Pp+Pr) excluding the pressure Ps produced by biasing force will be −0.5 kPa; and the absolute value Pf (0.5 kPa) of negative pressure (−0.5 kPa) will be sufficiently lower than the biasing force (5.0 kPa) of the spring  29  (Ps&gt;Pf). Thus, the displaceable member  27  will be pushed upward by the spring  29 . 
     At this point, as depicted in  FIG. 2  the flexible film of the liquid storage portion  7  (which is now substantially empty of liquid) will begin to dilate in reverse, and thus the pressure Pp resulting from rigidity of the flexible film that defines the liquid storage portion  7  will act so to suck back the liquid and bring the pressure inside the liquid sensing chamber  21  to negative pressure, for example to Pp=−3 kPa. If there is additional flow of liquid, the pressure drop Pr produced by fluid flow within the liquid storage portion  7  (whose flow channel has become constricted) will increase further, for example to Pp=−2.0 kPa. At this point, the sum of pressure inside the liquid sensing chamber  21  will be Ps+Pp+Pr=±0 kPa, which represents a state of equilibrium between the pressure Ps (=5 kPa) produced by biasing force of the bias force member  29  on the one hand, and other pressure (Pp+Pf) (=−5 kPa) on the other. That is, pressure (Pp+Pf) exclusive of biasing force Ps is −5 kPa; and the absolute value Pe (5 kPa) of negative pressure when the liquid is depleted is equal to the pressure Ps produced by biasing force of the bias force member  29  (Ps=Pe). This state represents the instant at which the displaceable member moves to the prescribed location; if the absolute value Pe of negative pressure is even slightly greater than this state (Ps&lt;Pe), the displaceable member  29  will move to the prescribed location in opposition to the biasing force of the spring  29 . 
     That is, as depicted in  FIG. 2 , when the amount of liquid in the liquid storage portion  7  falls below the predetermined amount in association with feed of liquid from the liquid feed port  9 , the pressure Ps produced by biasing force biasing the displaceable member  27  in the direction away from the prescribed location by the bias force member  29  will be lower than the absolute value Pe of negative pressure arising in the liquid sensing chamber  21  when liquid is fed from the liquid feed port  9  to the liquid consuming apparatus unit. 
     Consequently, the displaceable member  27  will undergo displacement to the prescribed location. Thus, the oscillation sensor  25  will sense that the amount of liquid in the liquid storage portion  7  is now less than the prescribed amount. As will be appreciated from the above discussion, in first embodiment, sensing of the location of the displaceable member  27  by the oscillation sensor  25  takes place while the liquid is being fed from the liquid feed port  9  to the liquid consuming apparatus unit, i.e. while fluid is flowing inside the liquid sensing chamber  21  due to suctioning of the liquid feed port  9  by the liquid consuming apparatus. 
     Such displacement of the displaceable member  27  will take place one time before the liquid in the liquid storage portion  7  is exhausted. Additionally, there will be no need for pressurizing means in order to pressurize the perimeter of the liquid storage portion  7  in order to feed liquid from the liquid container  1 . That is, according to this liquid container  1 , liquid can be supplied through suction force on the liquid consuming apparatus side, thus obviating the need for pressurizing means and making possible lower cost, even where remaining liquid sensing means are provided. 
     Further, a check valve  15  is provided between the liquid sensing chamber  21  and the liquid storage portion  7 . This check valve  15  will block the flow of liquid attempting to backflow into the liquid storage portion  7  from the liquid sensing chamber  21 . The flexible film that defines the flexible portion  23  of the liquid sensing chamber  21  typically has lower gas barrier properties than does the multilayer flexible film that forms the liquid storage portion  7 . Thus, liquid inside the liquid sensing chamber  21  (which has lower gas barrier properties) will be prevented from backflowing into the liquid storage portion  7  (which has excellent gas barrier properties), and thus air bubbles can be prevented from being entrained into the liquid storage portion  7 . 
     Furthermore, as the bias force member  29 , the bias force member  29  is provided interposed between a flexible portion constituting a first face of the liquid sensing chamber (i.e. the flexible portion  23 ) and a face opposing this flexible portion  23  (i.e. the base face  19   b  of the sensing device case  19 ), between the displaceable member  27  and the base face  19   b.  When doing this, the displaceable member  27  and the flexible portion  23  constituting the first face of the liquid sensing chamber may be simply disposed in abutment without being attached. This is because the displaceable member  27  will be normally maintained in contact with the flexible portion  23  by being pushed against it by the bias force member  29 . Particularly where the bias force member  29  is a compression spring of truncated conical shape, displacement of the displaceable member  27  will be stabilized. Since the displaceable member  27  and the flexible portion  23  constituting the first face of the liquid sensing chamber  21  are not attached, the flexible portion  23  constituting the first face of the liquid sensing chamber  21  will not experience unwanted stress. However, the bias force member  29  is not limited to a compression spring of truncated conical shape, and the displaceable member  27  could instead be urged away from the prescribed location by a compression spring of tubular shape, a torsion coil spring, or the like. 
     Other Embodiments 
       FIG. 3  is a construction drawing depicting another embodiment of a liquid container according to the present invention.  FIG. 4  is an illustration of operation when the liquid inside the liquid container  7  has been consumed. In the drawings, parts identical or equivalent to those in the preceding embodiment are assigned like symbols. 
     This embodiment differs from the embodiment described previously in that a check valve  14  for blocking flow of liquid from the liquid feed port  9  to the liquid sensing chamber  21  is provided between the liquid feed port  9  and the liquid outlet  11   b.    
     According to this liquid container, when liquid equal to or greater than a prescribed amount (an amount sufficient for delivery to the liquid sensing chamber  21 ) is present in the liquid storage portion  7 , the displaceable member  27  will undergo displacement away from the prescribed location by the bias force member  29 . The oscillation sensor  25  will therefore sense that liquid is present in the liquid storage portion  7  in an amount equal to or greater than the prescribed amount. 
     Meanwhile, the amount of liquid in the liquid storage portion  7  and in the liquid sensing chamber  21  will progressively decrease as the liquid is fed out from the liquid feed port  9 . Once a given decrease is reached or exceeded, the displaceable member  27  will undergo displacement to the prescribed location. Thus, the oscillation sensor  25  will sense that the amount of liquid in the liquid storage portion  7  is less than the prescribed amount. 
     In the liquid container depicted in  FIG. 3 , the check valve  14  for blocking flow of liquid from the liquid feed port  9  to the liquid sensing chamber  21  is disposed between the liquid feed port  9  and the liquid outlet  11   b  from the liquid sensing chamber  21 . Thus, if for some reason, such as entrainment through a liquid ejection nozzle of the liquid consuming apparatus unit, an air bubble should become entrained into the liquid flow channel on the downstream side from the feed needle  40  of the liquid consuming apparatus (the upstream side in relation to the direction of liquid feed), the bubble will be prevented from infiltrating the liquid sensing chamber  21 . 
     If an air bubble should infiltrate the liquid sensing chamber  21 , and if the air bubble should then infiltrate the liquid conducting path  33  used for sensing the presence of liquid, sensor error may result. According to this embodiment however, infiltration of air bubbles into the liquid sensing chamber  21  is prevented, so sensor error will not occur. This liquid container affords additional advantages deriving from its comparable design to the preceding embodiment. 
     The risk of backflow as described above will be greater in a pressurized system in which liquid is delivered by pressurizing the perimeter of the liquid storage portion, than it is in a non-pressurized system in which liquid is delivered through suction as in the present embodiment. The reason is that in a pressurized system, biasing force of the bias force member will act in a direction so as to push out backflow, whereas in a non-pressurized system biasing force of the bias force member  29  will act in a direction so as to draw in backflow. 
     (Liquid Consuming Apparatus) 
     The liquid container  1  depicted in  FIGS. 1 and 3  is designed such that the liquid feed needle  40  of the liquid consuming apparatus unit can connect to its liquid feed port  9  to feed the liquid inside the liquid container  1  to the liquid consuming portion (e.g. an inkjet head) on the basis of head difference or liquid suction action in the liquid consuming portion. The liquid feed needle  40  functions as a liquid intake portion for drawing liquid into the liquid consuming apparatus unit from the liquid container  1  via the liquid feed port  9 . In this case, the contraction operation of the flexible portion  23  in the liquid container  1  will basically take place one time. 
     By providing the liquid consuming apparatus unit with a pump however, liquid feed to the liquid consuming portion can be stabilized further. An embodiment of a liquid consuming apparatus unit furnished with a pump will be described below. 
       FIG. 5  is a schematic diagram depicting an embodiment of a liquid consuming apparatus according to the present invention. This liquid consuming apparatus unit is equipped with a liquid feed needle  40  for connection to the liquid feed port  9  of the liquid container  1  having the check valve  14  shown in  FIG. 3 ; and with a diaphragm pump  42  disposed between the liquid intake portion  40  and the liquid consuming portion  46 , for delivering liquid from the liquid feed needle  40  to the liquid consuming portion (in this embodiment, a recording head)  46 . The diaphragm pump  42  is designed to deliver liquid through application of external force in a direction expanding its volume from a previous state of having been urged in the direction of reduced internal volume, followed by subsequent release of this external force. The pressure acting on the liquid sensing chamber  21  as a result of this external force applied in a direction expanding the volume of the diaphragm pump  42  will be greater than the pressure applied to the liquid sensing chamber  21  by the biasing force of the bias force member  29  which urges the flexible portion  23  of the liquid sensing chamber  21 . 
     The liquid consuming apparatus unit is additionally provided with a cap  47 , a suction pump  48 , and a waste ink absorber  49 . The cap  47  is adapted to cover the nozzle face of the liquid consuming portion  46  when the liquid consuming portion  46  (recording head) is at the home position. The suction pump  48  is used to eliminate clogging by forcibly suctioning out ink from a nozzle through the cap  47  when a nozzle of the liquid consuming portion  46  has become clogged. The waste ink absorber  49  is used to absorb waste ink from the suction pump  48 . 
     The liquid feed needle  40  is composed of a liquid feed needle (e.g. an ink feed needle) of known design adapted to insert into the liquid feed port  9 . The liquid feed needle  40  has on its peripheral face an ink inlet hole  40   a,  and a liquid channel  40   b  communicating with this ink inlet hole  40   a.  The liquid consuming portion  46  is composed of an inkjet head of known design, for example. 
     The diaphragm pump  42  has a decompression chamber  42   a;  a diaphragm chamber  42   c  defined by a diaphragm  42   b  inside this decompression chamber  42   a;  and a compression spring  42   d  adapted to urge the diaphragm  42   b  in the direction of decreasing volume of the diaphragm chamber  42   c.  An air vent valve  51 , an air passage pressure sensor  52 , and a decompression pump  53  connect with the decompression chamber  42   a  through an air passage  50 . 
     A liquid inlet  42   i  of the diaphragm chamber  42   c  connects to the liquid feed needle  40  via an on-off valve  41 . A liquid outlet  42   o  of the diaphragm chamber  42   c  connects to the liquid consuming portion  46  via a check valve  43 , a liquid feed passage  44 , and a pressure regulating valve (self sealing valve) of known design. The pressure produced by the compression spring  42   d  which urges the diaphragm  42   b  of the diaphragm pump  42  will be a pressurizing force equal to or greater than the level necessary to feed liquid to the liquid consuming portion (recording head)  46  at a consistently sufficient feed. 
       FIGS. 6 to 8  are drawings illustrating operation of the liquid consuming apparatus. The diaphragm pump  42  operates in the following manner. 
     (i) As depicted in  FIG. 6 , with the on-off valve  41  open, the decompression pump  53  is operated to draw out air (A) from the decompression chamber  42   a  as indicated by the arrow A and decompress the decompression chamber  42   a,  causing the diaphragm  42   b  to distend in opposition to the compression spring  42   d,  and liquid to be suctioned from the liquid storage portion  7  into the diaphragm chamber  42   c  as indicated by arrow F. 
     (ii) Subsequently, as depicted in  FIG. 7 , when the decompression pump  53  is stopped and the air vent valve  51  is opened, air (A) will inflow to the decompression chamber  42   a  as indicated by arrow A and the decompression chamber  42   a  will reach atmospheric pressure, and thus the diaphragm  42   b  will now be compressed by the spring  42   d,  the passage in the liquid feed passage  44  interior and leading up to the check valve  14  in the liquid container  1  interior will assume a pressurized state, and liquid will be fed appropriately to the liquid consuming portion  46 . 
     (iii) Subsequently, as depicted in  FIG. 8 , the liquid will be consumed by the liquid consuming portion  46 , and at the point in time that no more liquid remains inside the diaphragm chamber  42   c,  the operations of (i) and (ii) above will repeat. 
     (Working Effects of Liquid Consuming Apparatus) 
     According to this liquid consuming apparatus, because the liquid container  1  has a check valve  14 , liquid can be supplied to the liquid consuming portion  46  by the diaphragm pump  42 , without necessarily having to provide a check valve between the liquid feed needle  40  and the diaphragm pump  42  (the location of the on-off valve  41 ). The cost of the liquid consuming apparatus can be reduced thereby. 
     Furthermore, according to this liquid consuming apparatus, if the decompression level acting on the liquid sensing chamber  21  of the liquid container  1  (i.e. the pressure loss arising in the connecting passage between the liquid storage portion  7  and the liquid sensing chamber  21  due to the flow rate outflowing from the liquid storage portion  7  because of distension of the diaphragm pump through application of the external force) when external force is applied in the direction of expansion of volume of the diaphragm pump  42  as depicted in  FIG. 6  has been set to a low level, if sufficient liquid is present in the liquid container  1 , the liquid sensing chamber  21  will experience substantially no change in volume. 
     On the other hand, if the level of liquid in the liquid storage portion  7  is so low that liquid cannot be supplied to the liquid sensing chamber  21 , when external force is applied in the direction of expansion of volume of the diaphragm pump  42 , the volume of the liquid sensing chamber  21  will decrease (see  FIG. 7 ). Consequently, owing to the above pressure relationships, it will be possible to utilize change in volume of the liquid sensing chamber  21  to sense the remaining amount of liquid. 
     Furthermore, according to this liquid consuming apparatus, because the liquid passage connecting the diaphragm pump  42  and the liquid feed needle  40  is provided with a on-off valve  41  capable of opening and closing irrespective of the flow of liquid, when the liquid feed needle  40  and the liquid feed port  9  of the liquid container  1  are disconnected, liquid can be prevented from dripping from the liquid feed needle  40  by shutting the on-off valve  41 . 
     (Variations of Liquid Consuming Apparatus) 
     While not illustrated in the drawings, in a liquid consuming apparatus according to another embodiment, a check valve can be provided between the diaphragm pump  42  and the liquid feed needle  40  to block the flow of liquid from the diaphragm pump  42  to the liquid feed needle  40  (while allowing flow in the opposite direction). The check valve can be disposed in series with the on-off valve  41 , or provided in place of the on-off valve  41 . 
     Such a liquid consuming apparatus will afford advantages comparable to the liquid consuming apparatus described previously. Additionally, because the device has a check valve provided between the diaphragm pump  42  and the liquid feed needle  40  to block the flow of liquid from the diaphragm pump  42  to the liquid feed needle  4 , a liquid container that lacks a check valve  14  can be used. 
     B. Second Embodiment 
       FIG. 9  is a drawing illustrating biasing force by an bias force member  29   b  in a second embodiment. This second embodiment differs from first embodiment in that sensing of the location of the displaceable member  27  by the oscillation sensor  25  takes place during periods in which liquid is not being fed from the liquid feed port  9  to the liquid consuming apparatus unit, that is, when the liquid consuming apparatus is not suctioning the liquid feed port  9 , and liquid is not flowing through the liquid sensing chamber  21 . Thus, the pressure Psb produced by biasing force of the bias force member  29   b  will be set to a different value from first embodiment. 
       FIG. 9  depicts a graph showing the relationship between the remaining amount of liquid in the liquid storage portion  7  and negative pressure inside the liquid sensing chamber  21 . The vertical axis at left in  FIG. 9  indicates negative pressure (Pb+Pr) arising inside the liquid sensing chamber  21 . Graph G 1  shows an instance in which there is no flow of liquid (ink) in the liquid sensing chamber  21  (i.e. where the flow rate is 0), whereas graph G 2  shows an instance in which there is flow of liquid (ink) in the liquid sensing chamber  21  (i.e. where the flow rate is not 0). It will be appreciated that, as shown in  FIG. 9 , regardless of whether there is no flow of liquid (graph G 1 ) or there is flow of liquid (graph G 2 ), the absolute value of negative pressure inside the liquid sensing chamber  21  will be progressively greater the smaller the amount of liquid remaining in the liquid storage portion  7 . That is, the pressure of liquid inside the liquid sensing chamber  21  will be progressively lower the smaller the amount of remaining liquid in the liquid storage portion  7 , with respect to atmospheric pressure. From  FIG. 9  it will be appreciated that the absolute value of negative pressure inside the liquid sensing chamber  21  in instances where there is flow of liquid in the liquid sensing chamber  21  (graph G 2 ) is greater than the absolute value of negative pressure inside the liquid sensing chamber  21  in instances where there is no flow of liquid in the liquid sensing chamber  21  (graph G 1 ). The reason is that where there is flow of liquid, a pressure drop Pr will arise due to the flow of liquid. 
     Here, as described in first embodiment, where there is flow of liquid in the liquid sensing chamber  21  (graph G 2 ), negative pressure (differential pressure from atmospheric pressure) Pp+Pr inside the liquid sensing chamber  21  will reach −5.0 kPa when the remaining amount of ink in the liquid storage portion  7  has reached a prescribed value (in  FIG. 9 , 5 g). In first embodiment, the pressure Ps arising through biasing force by the bias force member  29  is set to Ps=+5.0 kPa. As a result, if the absolute value of the negative pressure Pp+Pr inside the liquid sensing chamber  21  goes above 5.0 kPa, the displaceable member  27  will assume a state in which it substantially abuts against the base plate  31  (a state of being at the prescribed location). As a result, during the time that there is flow of liquid in the liquid sensing chamber  21 , i.e. during the time that the liquid feed port  9  is being suctioned by the liquid consuming apparatus, by sensing with the oscillation sensor  25  whether the displaceable member  27  is at the prescribed location, the liquid consuming apparatus will be able to sense whether the amount of remaining ink in the liquid storage portion  7  is equal to or less than the prescribed value. 
     On the other hand, where there is no flow of liquid in the liquid sensing chamber  21  (graph G 1 ), negative pressure (differential pressure from atmospheric pressure) Pp inside the liquid sensing chamber  21  will reach −3.0 kPa when the remaining amount of ink in the liquid storage portion  7  has reached a prescribed value (in  FIG. 9 , 5 g). In second embodiment, the pressure Psb arising through biasing force by the bias force member  29  is set to Psb=+3.0 kPa. As a result, if the absolute value of the negative pressure Pp inside the liquid sensing chamber  21  goes above 3.0 kPa, the displaceable member  27  will assume a state in which it substantially abuts against the base plate  31  (a state of being at the prescribed location). As a result, at times of no flow of liquid in the liquid sensing chamber  21 , i.e. at times that the liquid feed port  9  is not being suctioned by the liquid consuming apparatus, by sensing with the oscillation sensor  25  whether the displaceable member  27  is at the prescribed location, the liquid consuming apparatus will be able to sense whether the amount of remaining ink in the liquid storage portion  7  is equal to or less than the prescribed value. 
     For example, in the liquid consuming apparatus, if the circuit that supplies driving power to the piezoelectric element of the oscillation sensor  25  and the circuit that supplies driving power to the liquid consuming portion (recording head)  46  constitute a shared circuit, it will not be possible for the oscillation sensor  25  to be driven while the liquid consuming portion  46  is being driven. The liquid consuming apparatus suctions the liquid feed port  9  during driving of the liquid consuming portion  46 , i.e. when liquid is being consumed. As a result, if the circuit that supplies driving power to the piezoelectric element of the oscillation sensor  25  and the circuit that supplies driving power to the liquid consuming portion (recording head)  46  constitute a shared circuit, there will be instances in which the liquid consuming apparatus cannot drive the oscillation sensor  25  during periods of flow of liquid in the liquid sensing chamber  21 . According to second embodiment, at times of no flow of liquid in the liquid sensing chamber  21 , i.e. when the liquid consuming apparatus is not driving the liquid consuming portion  46 , it can drive the oscillation sensor  25  and sense whether the amount of remaining ink in the liquid storage portion  7  is equal to or less than the prescribed value. Consequently, in such a liquid consuming apparatus, the circuit that supplies driving power to the piezoelectric element of the oscillation sensor  25  and the circuit that supplies driving power to the liquid consuming portion (recording head)  46  can be a shared circuit. The number of parts of the liquid consuming apparatus can be reduced thereby, to achieve a more compact size. 
     Apart from the setting of the biasing force of the bias force member  29 , the arrangement of second embodiment is comparable to first embodiment and will not be described in detail. 
     While preferred embodiments have been described in detail hereinabove, numerous modifications will be readily apparent to the practitioner of the art without substantially departing from the novelty and effects of the present invention. Accordingly, such modified examples will fall within the scope of the present invention. For example, terms that in at least one instance appear together with different terms of broader or identical meaning in the specification and drawings may be replaced with these different terms, at any point in the specification or drawings. 
     For example, the point in time at which the displaceable member  27  and the base plate  31  cooperate to define a sealed space in the liquid conducting path  33  can be set to a state in which the liquid in the liquid storage portion  7  has been substantially exhausted (near-end condition). By so doing, where employed as an ink cartridge for example, the piezoelectric sensing means of the liquid sensing device  11  can be effectively utilized as near-end sensing means adapted to sense a condition in which the amount of remaining ink in the liquid storage portion  7  is approaching zero. 
     The liquid container of the present invention is not limited to application in liquid cartridges for use in liquid jet recording devices. It may be adapted for use in liquid consuming apparatus of various kinds equipped with a liquid jetting head adapted to eject small amounts of a liquid in drop form. Herein, a drop refers to a state of a liquid as ejected from the liquid consuming apparatus, and includes granular, teardrop, or filiform shape with a tail. 
     Specific examples of liquid consuming apparatus include devices equipped with a coloring matter jetting head used to manufacture color filters for liquid crystal displays or the like; devices equipped with an electrode material (electrode paste) jetting head used to produce electrodes for organic EL displays, field emission displays (FED) or the like; devices equipped with a biooorganic substance jetting head used for biochip manufacture; devices equipped with a specimen jetting head as a precision pipette; textile printing devices; and microdispensers. 
     In the present invention, a liquid refers to any material capable of being jetted from a liquid consuming apparatus. Liquids such as those described in the preceding embodiments are typical examples of such liquids. The liquid could be a substance besides materials employed for printing of text and images, such as liquid crystals. In the present invention, the liquid is not limited to a liquid as one state of matter, and may also be a liquid as one state of matter incorporating a solid such as pigments or metal particles. 
     While the technology pertaining to the invention have been shown and described on the basis of the embodiments and variations, the embodiments of the invention described herein are merely intended to facilitate understanding of the invention, and implies no limitation thereof. Various modifications and improvements of the invention are possible without departing from the spirit and scope thereof as recited in the appended claims, and these will naturally be included as equivalents in the invention. 
     C. Variations 
     Variation 1: A liquid consuming system comprising a liquid consuming apparatus and a liquid container attachable to the liquid consuming apparatus, wherein
         the liquid container includes:
           a liquid storage portion that stores a liquid;   a liquid feed portion that connects with the liquid consuming apparatus and feeds the liquid to the liquid consuming apparatus when the liquid container is attached to the liquid consuming apparatus;   a liquid sensing chamber defining portion having a liquid inlet communicating with the liquid storage portion and a liquid outlet communicating with the liquid feed portion and that defines a liquid sensing chamber that fluctuates in volume according to a differential between atmospheric pressure received from an outside and pressure received from an inside;   a bias force member that exerts a bias force on the liquid sensing chamber from an inner side in a direction of expansion of volume of the liquid sensing chamber; and   a sensor that senses a decline in volume of the liquid sensing chamber to a prescribed volume value,   
           wherein a pressure of liquid present in the liquid sensing chamber declines as a amount of liquid in the liquid storage portion becomes lower, and   the bias force is established such that if the amount of liquid in the liquid storage portion is equal to or greater than a prescribed amount, the liquid sensing chamber overcomes atmospheric pressure to assume a volume exceeding a prescribed volume value, whereas if the amount of liquid in the liquid storage portion is less than a prescribed amount, the liquid sensing chamber yields to atmospheric pressure to assume a volume equal to or less than a prescribed volume value,   the liquid consuming apparatus includes:
           a liquid intake portion connected to the liquid feed portion of the liquid container;   a liquid consuming portion; and   a diaphragm pump disposed between the liquid intake portion and the liquid consuming portion and adapted to deliver the liquid to the liquid consuming portion via the liquid intake portion through application of external force in a direction of expansion of volume thereof from a previous state of having been urged in the direction of reduction of internal volume followed by subsequent release of the external force;   
           and wherein pressure acting on the liquid sensing chamber resulting from the external force is greater than pressure produced by the bias force of the bias force member.       

     Variation 2: The liquid consuming system in accordance with Variation 1, wherein
         the liquid container further includes a check valve disposed between the liquid feed portion and the liquid outlet, and adapted to block backflow of the liquid from the liquid feed portion towards the liquid sensing chamber.       

     Variation 3: The liquid consuming system in accordance with Variation 1, wherein
         the liquid consuming apparatus further includes an on-off valve disposed between the diaphragm pump and the liquid intake portion.       

     Variation 4: A liquid consuming apparatus comprising:
         a liquid consuming apparatus unit; and   a liquid container attached to the liquid consuming apparatus unit;   wherein the liquid container includes:
           a liquid storage portion that stores a liquid for feeding to the liquid consuming apparatus unit and composed at least in part of a flexible member;   a liquid feed port connected to the liquid consuming apparatus unit and adapted to feed liquid stored in the liquid storage portion to the liquid consuming apparatus unit; and   a liquid sensing device adapted to sense the remaining amount of liquid inside the liquid storage portion,   
           wherein the liquid sensing device includes:
           a liquid sensing chamber having a liquid inlet that communicates with the liquid storage portion and a liquid outlet that communicates with the liquid feed port;   a flexible portion defining one face of the liquid sensing chamber and adapted to deform in response to the amount of liquid inside the liquid sensing chamber;   a displaceable member housed within the liquid sensing chamber and capable of displacement actuated by deformation of flexible portion;   sensing means adapted to sense displacement of the displaceable member to a prescribed location; and   a bias force member adapted to urge the flexible portion in the direction of expansion of volume of the liquid sensing chamber,   
           wherein the liquid consuming apparatus unit includes:
           a liquid intake portion connected to the liquid feed port of the liquid container;   a liquid consuming portion;   a diaphragm pump disposed between the liquid intake portion and the liquid consuming portion for the purpose of feeding liquid from the liquid intake portion to the liquid consuming portion and adapted to deliver liquid through application of external force in the direction of expansion of volume thereof from a previous state of having been urged in the direction of reduced volume followed by subsequent release of the external force; and   a check valve disposed between the diaphragm pump and the liquid intake portion and adapted to block backflow of liquid from the diaphragm pump towards the liquid intake portion,   
           and wherein pressure acting on the liquid sensing chamber resulting from external force applied in the direction of expansion of volume of the diaphragm pump will be greater than pressure applied to the liquid sensing chamber resulting from biasing force of the bias force member.       

     Variation 5: A liquid consuming apparatus comprising:
         a liquid consuming apparatus unit; and   a liquid container attached to the liquid consuming apparatus unit;   wherein the liquid container includes:
           a liquid storage portion adapted to store a liquid for feeding to the liquid consuming apparatus unit and composed at least in part of a flexible member;   a liquid feed port connected to the liquid consuming apparatus unit and adapted to feed liquid stored in the liquid storage portion to the liquid consuming apparatus unit; and   a liquid sensing device adapted to sense the remaining amount of liquid inside the liquid storage portion,   
           wherein the liquid sensing device includes:
           a liquid sensing chamber having a liquid inlet that communicates with the liquid storage portion and a liquid outlet that communicates with the liquid feed port;   a flexible portion defining one face of the liquid sensing chamber and adapted to deform in response to the amount of liquid inside the liquid sensing chamber;   a displaceable member housed within the liquid sensing chamber and capable of displacement actuated by deformation of flexible portion;   sensing means adapted to sense displacement of the displaceable member to a prescribed location; and   a bias force member adapted to urge the flexible portion in the direction of expansion of volume of the liquid sensing chamber,   
           wherein the liquid container further includes a check valve disposed between the liquid feed port and the liquid outlet provided to the liquid sensing chamber and adapted to block backflow of liquid from the liquid feed port towards the liquid sensing chamber,   wherein the liquid consuming apparatus unit includes:
           a liquid intake portion connected to the liquid feed port of the liquid container;   a liquid consuming portion; and   a diaphragm pump disposed between the liquid intake portion and the liquid consuming portion for the purpose of feeding liquid from the liquid intake portion to the liquid consuming portion and adapted to deliver liquid through application of external force in the direction of expansion of volume thereof from a previous state of having been urged in the direction of reduced volume followed by subsequent release of the external force,   
           and wherein pressure acting on the liquid sensing chamber resulting from external force applied in the direction of expansion of volume of the diaphragm pump will be greater than pressure applied to the liquid sensing chamber resulting from biasing force of the bias force member.       

     Variation 6: The liquid consuming apparatus in accordance with Variation 4 or 5, wherein
         an on-off valve is disposed on the liquid flow channel connecting the diaphragm pump and the liquid intake portion.