Abstract:
The invention provides a liquid storage unit comprising: a case, a liquid storage part for storing a liquid in the case, with which a liquid part communicates; at least one gas accommodation part for accommodating a gas in the case, with which a gas port communicates, wherein the liquid in the liquid storage part is led outs through the liquid port by a pressure of a gas introduced from the gas port; an inner case provided in the case having a pair of openings on opposite side faces thereof; and a pair of flexible partitioning members sealing said pair of openings of the inner case respectively, thereby partitioning the liquid storage part therebetween and defining said at least one of the gas accommodation part in cooperation with the case.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation of copending application Ser. No. 10/782,467, filed on Feb. 19, 2004, the entire contents of which are incorporated by reference herein. 
     
    
       [0002]    The present application also is based on Japanese Patent Application No. 2003-40631; the entire contents of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0003]    1. Field of the Invention 
         [0004]    The present invention relates to liquid storage unit and a liquid ejecting apparatus mounting the liquid storage unit thereon. 
         [0005]    2. Related Art 
         [0006]    Conventionally, a liquid ejecting apparatus for injecting a droplet from the nozzle of a liquid ejection head includes an ink jet printer. Some ink jet printers include an ink supply system of an off carriage type for mounting an ink cartage in a place other than a carriage. The case in which the ink supply system of the off carriage type is provided includes the case in which an ink cartridge having a large capacity is provided for large printing and the case in which the ink cartridge is not mounted but the size of a carriage is reduced and the size and thickness of the ink jet printer is decreased. 
         [0007]    In the ink supply system of the off carriage type, for example, the ink cartridge is provided on a body side. An ink is supplied from the ink cartridge to a subtank mounted on the carriage through a supply tube. On the other hand, there is a problem in that the dynamic pressure of the ink in the supply tube is raised because of an increase in the flow of the ink due to an increase in the speed and fineness of the printing of a printer, resulting in the insufficiency of the amount of the ink supplied to the subtank. 
         [0008]    In order to solve the problem, there has been proposed an ink cartridge for accommodating a bag-shaped ink pack in the case of the ink cartridge and introducing air between the case and the ink pack, thereby pressurizing the ink pack to forcibly lead out an ink (for example, see JP-A-2001-212973). 
         [0009]    In the ink cartridge for accommodating the bag-shaped ink pack in the case, however, it is necessary to raise an air pressure between the case and the ink pack. For this reason, the opening portion of the case for attaching the ink pack is to be sealed in an airtight state as shown in  FIG. 10 . In an ink cartridge  51 , a plug member  55  sealing the opening portion of an ink pack  54  is protruded from an opening portion  53  formed on a case  52  toward an outside. In this state, an O-ring  56  is attached to the opening portion  53 , and furthermore, an engaging member  57  is pushed in from the outside of the case  52 . Consequently, the plug member  55  is fixed to the opening portion  53  in the airtight state. 
         [0010]    In the ink cartridge for accommodating the bag-shaped ink pack in the case, accordingly, a seal member for enhancing a sealing property is required and the structure of the seal member is complicated. Accordingly a cost is increased or the size of an apparatus is increased in some cases. 
         [0011]    To cope with the above problems, there have been proposed an ink cartridge (for example, JP S59-209878A) in which a bag member provided with a flexible film covers a recessed face of the cartridge body so that an ink is filled in a space formed between the bag member and the recessed face. A rigid lid having recess corresponding to the bag member filled with the ink is attached on the cartridge body. The bag member is pressurized by providing air between the bag member and the lid so that the ink is led out from the cartridge. 
         [0012]    Since any ink pack is not housed, no sealing member for ink pack is provided in the cartridge. Therefore, such the ink cartridge can be provided with a simple structure in small size at low cost. 
         [0013]    Meanwhile, even in the cartridge as disclosed in JP S59-209878A, it is important to keep sufficient deaeration degree of the ink for maintaining the quality of ink. However, in the ink cartridge of JP S59-209878A, the space in which the ink is filled is formed by the flexible film on one side face and the rigid main body on the other side faces. The main body of the cartridge is usually made of a plastic resin with a low gas barrier property. Therefore, even if only one side face is covered with the film with high gas barrier property, the total degree of deaeration of the ink filled in the space does not reach sufficiently high since a large portion of the surface of the space is defined by the main body 
         [0014]    Further, in JP S59-209878A, a space into which air is introduced is formed by fixing the rigid lid onto the rigid cartridge body. Accordingly, for fixing the lid onto the main body, it is necessary to use a simple manufacturing device and to avoid generation of foreign substances by operation as much as possible. 
         [0015]    The invention relates to a liquid storage unit which is available by a simple manufacturing device, avoiding generation of foreign substances, and a liquid ejection apparatus in which the liquid storage unit is mounted. 
       SUMMARY OF THE INVENTION 
       [0016]    The invention provides a liquid storage unit comprising:
       a case;   a liquid storage part for storing a liquid in the case, with which a liquid port communicates;   at least one gas accommodation part for accommodating a gas in the case, with which a gas port communicates, wherein the liquid in the liquid storage part is led out through the liquid port by a pressure of a gas introduced from the gas port;   an inner case provided in the case having a pair of openings on opposite side faces thereof; and   a pair of flexible partitioning members sealing said pair of openings of the inner case respectively, thereby partitioning the liquid storage part therebetween and defining said at least one of the gas accommodation part in cooperation with the case.       
 
         [0022]    According to the liquid storage unit of the invention, the air accommodation part can be formed only by partitioning the inside of the case with a partitioning member. Among the faces with which the ink storage part is defined, two side faces are provided with the flexible partitioning members, and the other faces are provided with the inner case. By such the structure, the surface of the liquid storage part which is defined by the inner case made of a material with low gas barrier property can be small, whereas the surface which is defined by the partitioning members made of a material with high gas barrier property can be large for example. As a result high degree of deaeration can be obtained in the liquid storage part. Moreover, by providing two flexible partitioning members on the liquid storage part, even if the flexibility of the individual partitioning member is not so high, the total flexibility provided by both partitioning members for the liquid storage part can be high. As a result, remaining ink amount can be reduced by such the structure. 
         [0023]    In the liquid storage unit according to the invention, the flexible partitioning member is provided with a flexible film, which is thermally welded to a welding portion at the opening of the inner case. 
         [0024]    According to the above structure, among the faces with which the ink storage part is defined, two side faces are provided with the flexible films, and the other faces are provided with the inner case. By such the structure, the surface of the liquid storage part which is defined by the inner case made of a material with low gas barrier property can be small, whereas the surface which is defined by the flexible films made of a material with high gas barrier property can be large for example. As a result high degree of deaeration can be obtained in the liquid storage part. Moreover, by providing two flexible films on the liquid storage part, even if the flexibility of the individual film is not so high, the total flexibility provided by both films for the liquid storage part can be high. As a result, remaining ink amount can be reduced by such the structure. 
         [0025]    In the liquid storage unit according to the invention, the flexible film has a laminate structure including at least a welding layer weldable to the welding portion and a gas barrier layer. 
         [0026]    According to the above structure, it is possible to provide a liquid storage part accomplishing a higher degree of deaeration. Moreover, by providing two flexible films on the liquid storage part, even if the flexibility of the individual film is not so high, the total flexibility provided by both films for the liquid storage part can be high. As a result, the remaining ink amount can be reduced by such the structure. 
         [0027]    In the liquid storage unit according to the invention, the case in which the inner case is provided has openings at a pair of side faces thereof corresponding to the openings of the inner case, and lids are sealed on the openings of the case respectively. 
         [0028]    According to the above structure, by closing two openings with the lids, the liquid storage part is interposed between two air accommodation parts. Even if the remaining liquid in the liquid storage part becomes small, both of the flexible films can be flexed by introducing the air into both air accommodation parts. Therefore, even in a case that the remaining liquid in the liquid storage part is small, the liquid can be pressurized and ejected by flexion of both films. 
         [0029]    The invention also provides a liquid storage unit comprising:
       a case having an opening on a side face thereof;   a liquid storage part for storing a liquid in the case, with which a liquid port communicates;   at least one gas accommodation part for accommodating a gas in the case, with which a gas port communicates, wherein the liquid in the liquid storage part is led out through the liquid port by a pressure of a gas introduced from the gas port;   a first flexible partitioning member thermally welded to the case so as to define the liquid storage part in cooperation with the case;   a second flexible partitioning member sealing the opening of the case by thermal welding so as to define said at least one gas accommodation part in cooperation with the first partitioning member and the case.       
 
         [0035]    According to the invention, by thermally welding the flexible film onto the opening of the case, few foreign substances are generated in thermal welding. Therefore, adherence of the foreign substance is not occurred. Moreover, the thermal welding can be performed easily compared to other welding methods. Therefore, the liquid storage unit having large capacity can be manufactured in an easy and simple manner. 
         [0036]    In the liquid storage unit according to the invention, a protecting lid covering the second flexible partitioning member sealing the opening is provided in the case. 
         [0037]    According to the above structure, the protecting lid covers the opening of the case. Therefore, breakage of the partitioning member can be prevented. Further, the portioning member forming the gas accommodation part by sealing the case also serves as a lid of the case. Therefore, it is not necessary to hermetically seal the protecting lid to the case, so that selection of material for the protecting lid is not restricted. Accordingly, the material for the protecting lid can be freely selected in a suitable manner in a case that importance is placed on the appearance of the cartridge. 
         [0038]    The invention is also directed to a liquid ejecting apparatus comprising a liquid ejection head for discharging a liquid supplied from the liquid storage unit according to the invention, and a carriage for being reciprocated with the liquid ejection head mounted thereon. 
         [0039]    According to the above structure, there is provided the liquid ejecting apparatus in which can the liquid can be supplied to the liquid ejecting head even if the liquid becomes small in the liquid storage unit in which the degree of deaeration is suitably maintain. Moreover, the total cost for manufacturing the liquid ejecting apparatus can be reduced by providing the liquid storage unit mounted in the apparatus to be a simple structure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0040]      FIG. 1  is a plan view showing a printer body according to a first embodiment, 
           [0041]      FIG. 2  is a typical view showing an ink supply system according to the first embodiment, 
           [0042]      FIG. 3  is a plan view showing an ink cartridge according to the first embodiment, 
           [0043]      FIG. 4  is a sectional view showing the ink cartridge taken along an IV-IV line, 
           [0044]      FIG. 5  is a sectional view showing the main parts off the ink cartridge taken along a V-V line, 
           [0045]      FIG. 6  is a plan view showing an ink cartridge according to a second embodiment, 
           [0046]      FIG. 7  is a plan view showing an ink cartridge according to a third embodiment, 
           [0047]      FIG. 8  is a sectional view showing the ink cartridge taken along a VIII-VIII line, 
           [0048]      FIG. 9  is a sectional view showing the ink cartridge taken along an IX-IX line, and 
           [0049]      FIG. 10  is a sectional view showing the main parts of a conventional ink cartridge. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     First Embodiment 
       [0050]    A first embodiment according to the invention will be described below with reference to  FIGS. 1 to 5 . 
         [0051]    In an ink jet printer to be a liquid ejecting apparatus (which will be hereinafter referred to as a printer), a printer body  11  shown in  FIG. 1  is provided in a case which is not shown. The printer body  11  comprises a frame  12  and a paper feeding member  13  provided in the frame  12 . By a paper feeding mechanism which is not shown, a paper is delivered onto the paper feeding member  13 . Moreover, a guide member  14  is provided in parallel with the paper feeding member  13  between a right side plate  12   a  and a left side plate  12   b  in the frame  12 , and a carriage  15  is slidably supported on the guide member  14 . The carriage  15  is connected to a carriage motor  17  provided on a back plate  12   c  of the frame  12  through a timing belt  16 . The carriage  15  is reciprocated along the guide member  14  by the driving operation of the carriage motor  17 . 
         [0052]    Moreover, a recording head  20  to be a liquid ejection head is mounted on the surface of the carriage  15  which is opposed to the paper feeding member  13 . Furthermore, subtanks  21  to  24  for supplying the recording head  20  with an ink to be a liquid are mounted on the carriage  15 . In the embodiment, the four subtanks  21  to  24  are provided corresponding to inks for black, cyan, magenta and yellow. 
         [0053]    A nozzle discharge port (not shown) is formed on the lower face of the recording head  20 . By the driving operation of a piezoelectric unit which is not shown, the inks are discharged from respective corresponding nozzle discharge ports onto the paper so that printing is carried out. 
         [0054]    On the other hand, the right end of the frame  12  is provided with a cartridge holder  19  for removably mounting ink cartridges  45  to  48  to be liquid storage unit. In the embodiment, the four ink cartridges  45  to  48  are provided in the cartridge holder  19  corresponding to the inks having the four colors. The ink cartridges  45  to  48  are connected to an air pump  33  through air supply tubes  29  to  32 , and air to be a gas generated by the air pump  33  is supplied into the ink cartridges  45  to  48 . By pressurization into the ink cartridges  45  to  48 , the inks are supplied to the subtanks  21  to  24  through flexible ink supply tubes  34  to  37 , respectively. 
         [0055]      FIG. 2  is a typical view for explaining the structure of the ink supply system of the printer body  11 . The ink cartridges  45  to  48 , the air supply tubes  29  to  32  and the ink supply tubes  34  to  37  have the same structures, respectively. For convenience of explanation, description will be given to the ink supply system constituted by the ink cartridge  45  for supplying the ink to the subtank  21  and the description of the ink supply systems of the other ink cartridges  46  to  48  will be omitted. 
         [0056]    The air generated by the air pump  33  is first supplied to a pressure regulating valve  42 , and then, is supplied to the ink cartridge  45  through a pressure detector  41  and the air supply tube  29 . The pressure regulating valve  42  has the function of releasing a pressure to set an air pressure to be applied to the ink cartridge  45  within a predetermined range when an air pressure raised by the air pump  33  reaches a predetermined value or more. 
         [0057]    Moreover, the pressure detector  41  has the function of detecting the air pressure raised by the air pump  33 , thereby controlling the driving operation of the air pump  33 . More specifically, the pressure detector  41  stops the driving operation of the air pump  33  when detecting that the air pressure raised by the air pump  33  reaches a pressure having a predetermined value. The air pump  33  is controlled to be driven when the pressure detector  41  detects that the air pressure has the predetermined value or less. Thus, the pressure detector  41  has the function of repeating the driving operation of the air pump  33  and the stop of the driving operation, thereby maintaining the air pressure to be applied to the ink cartridge  45  within a predetermined range. 
         [0058]    The structure of the ink cartridge  45  will be described with reference to  FIGS. 3 to 5 .  FIG. 3  is a plan view showing a case  45   a  of the ink cartridge  45  seen from above. 
         [0059]      FIGS. 4 and 5  are sectional views showing an ink cartridge  45  according to the embodiment, illustrating sections taken along IV-IV and V-V lines in  FIG. 3  respectively, in which a case  45   a  is covered with lids  45   b,    45   c.  The ink cartridge  45  comprises the case  45   a  taking the shape of a square frame in which upper and lower faces are opened. The case  45   a  is sealed by covering opening portions on both faces with lids  45   b  and  45   c.    
         [0060]    Lid welding portions  45   e   1 ,  45   e   2  for welding the lids  45   b  and  45   c  are formed on two faces of upper and lower faces in the case  45   a  formed of polypropylene or the like, respectively. An inner case  45   a   2  is integrally formed within the case  45   a  through a joint frame  45   a   1 . The inner case  45   a   2  is formed with a square frame member having openings on two of the upper and lower faces on which film welding portions  45   d   1 ,  45   d   2  are formed respectively. Namely, the film welding portions  45   d   1 ,  45   d   2  are formed like square frames on the upper and lower faces. Lid welding portions  45   e   1 ,  45   e   2  are formed like square frames so as to surround the film welding portions  45   d   1 ,  45   d   2 . Moreover, the lid welding portions  45   e   1 ,  45   e   2  are formed To be protruded from the film welding portions  45   d   1 ,  45   d   2 . When two films  45   f   1 ,  45   f   2  to be flexible partitioning member are thermally welded to the film welding portions  45   d   1 ,  45   d   2  respectively, an ink chamber  45   g  to be liquid storage part is formed by the two films  45   f   1 ,  45   f   2  and the side faces of the inner case  45   a   2 . Incidentally, each of the films  45   f   1 ,  45   f   2  is constituted by a lamination of polypropylene, a gas barrier layer and nylon or the like from a welding face side. 
         [0061]    When the films  45   f   1 ,  45   f   2  are to be thermally welded to the film welding portions  45   d   1 ,  45   d   2 , the case  45   a  is fixed by a fixing device (not shown). Then, a heater chip (not shown) is caused to descend from above in a state in which the films  45   f   1 ,  45   f   2  are mounted on the film welding portions  45   d   1 ,  45   d   2 , and the films  45   f   1 ,  45   f   2  are thermally welded to the film welding portions  45   d   1 ,  45   d   2 . 
         [0062]    Further, the lids  45   b,    45   c  formed by the same material as the material of the case  45   a  are vibrated and welded to lid welding portions  45   e   1 ,  45   e   2  in a state that the films  45   f   1 ,  45   f   2  have been welded to the film welding portions  45   d   1 ,  45   d   2 . When the lids  45   b ,  45   c  are to be vibrated and welded to the lid welding portions  45   e   1 ,  45   e   2 , the lids  45   b,    45   c  abutting on the lid welding portions  45   e   1 ,  45   e   2  and the case  45   a  are interposed by two vibrating and welding devices (not shown), and a load is applied in a direction of a gravity by the driving operation of an actuator and they are driven to give a vibrating operation in a horizontal direction. By this operation, the lids  45   b,    45   c  are slid with a load applied to the lid welding portions  45   e   1 ,  45   e   2 . Accordingly, portions of the lids  45   b,    45   c  which abut on the lid welding portions  45   e   1 ,  45   e   2  and the lid welding portions  45   e   1 ,  45   e   2  are molten respectively by frictional heat generated therebetween. The vibration in the horizontal direction in the vibrating and welding device is stopped while keeping the load so that the lids  45   b,    45   c  are bonded to the lid welding portions  45   e   1 ,  45   e   2  in an airtight state. 
         [0063]    As a result, a first air chamber  45   h  is formed above the ink chamber  45   g  by the lid  45   b , the film  45   f   1  and the side faces of the case  45   a.  By the lid  45   c,  the film  45   f   2  and the side faces of the case  45   a,  a second air chamber  45   i  is formed below the ink chamber  45   g.  For this reason, the inside of the case  45   a  is partitioned into the ink chamber  45   g  and the two air chambers  45   h  and  45   i  by the two films  45   f   1 ,  45   f   2  and the ink chamber  45   g  is interposed between the air chambers  45   h  and  45   i.    
         [0064]    Moreover, a first connecting portion  45   j  for connecting the ink supply tube  34  and a second connecting portion  45   k  for connecting the air supply tube  29  are protruded from one of the side faces of the case  45   a . An ink lead-out port  45   m  penetrates through the first connecting portion  45   j  as shown in  FIG. 4 , and an air introducing port  45   n  penetrates through the second connecting portion  45   k  as shown in  FIG. 5 . The ink lead-out port  45   m  is formed to lead the ink stored in the ink chamber  45   g  to an outside, and has a valve  25   j  and a seal-member  25   k  provided therein. 
         [0065]    A hole  25   m  for a tube penetrates through the seal member  25   k . The hole  25   m  for a tube is constituted by a large diameter portion for fitting and inserting a supply needle (not shown) which is connected to the ink supply tube  34  and a small diameter portion. The same small diameter portion is provided to abut on a valve member  25   q  constituting the valve  25   j.  When the supply needle. connected to the ink supply tube  34  is inserted into the large diameter portion in this condition, the tip of the supply needle presses the valve member  25   q.  The valve member  25   q  is separated from the small diameter portion by pressing. Therefore, the ink is introduced from the ink chamber  45   g  into the ink lead-out port  45   m.    
         [0066]    As shown in  FIG. 5 , the air introducing port  45   n  penetrates through the second connecting portion  45   k , and furthermore, branches at the joint frame  45   a   1  provided on the inner faces of the case  45   a  in a vertical direction in the drawing, and one is opened in the air chamber  45   h  and the other is opened in the air chamber  45   i.  When the amount of the ink in the subtank  21  is decreased, therefore, the air is introduced from an air pump  33  to the first and second air chambers  45   h  and  45   i  through an air supply tube  29 . As a result, a pressure in each of the air chambers  45   h  and  45   i  is raised. By the pressure, each films  45   f   1 ,  45   f   2  are pressed and flexed toward the ink chamber  45   g . Consequently, the ink in the ink chamber  45   g  is led out of the ink lead-out port  45   m.  Also in the case in which the amount of the residual ink is small, therefore, the ink can be led out. 
         [0067]    The ink cartridge  45  having such a structure is provided in the printer body  11  in such a manner that the lids  45   b,    45   c  are almost parallel with the right side plate  12   a  and the left side plate  12   b  in the frame  12  as shown in  FIG. 1 . The ink led out of the ink cartridge  45  is introduced into the subtank  21  through the ink supply tube  34  as shown in  FIG. 2 . The ink supply tube  34  has an ink supply valve  34   a  provided in the middle thereof. The ink supply valve  34   a  is opened or closed so that the supply of the ink to the subtank  21  is controlled. 
         [0068]    The subtank  21  has a float member  21   a  provided therein, and a permanent magnet  21   b  is attached to one of the ends of the float member  21   a.  Magnetoelectric converting units  21   c  and  21   d  formed by Hall elements or the like attached to a substrate  21   e  and is provided on the side wall of the subtank  21 . By this structure, an electrical output is generated by the magnetoelectric converting units  21   c  and  21   d  corresponding to the amount of a line of magnetic force obtained by the permanent magnet  21   b  which is changed depending on the floating position of the float member  21   a.  For example, in the case in which the amount of the ink in the subtank  21  is decreased, the position of the float member  21   a  is moved downward in the direction of a gravity so that the position of the permanent magnet  21   b  is also moved downward. For this reason, the electrical outputs of the magnetoelectric converting units  21   c  and  21   d  can be sensed as the amount of the ink in the subtank  21 . If it is sensed that the amount of the ink is small, the ink supply valve  34   a  is opened. 
         [0069]    Consequently, the ink pressurized in the ink. cartridge  45  is led to the subtank  21  in which the amount of the ink is reduced. In the case in which the amount of the ink in the subtank  21  reaches a predetermined capacity, the ink supply valve  34   a  is closed based on the electrical outputs of the magnetoelectric converting units  21   c  and  21   d.  By the repetition of the opening and closing operations of the ink supply valve  34   a,  the ink is supplied into the subtank  21  and the almost constant ink is always stored in the subtank  21 . 
         [0070]    According to the first embodiment, the following advantages can be obtained. 
         [0071]    (1) In the first embodiment, the inner case  45   a   2  off the case  45   a  covered with the lids  45   b,    45   c  is partitioned by the films  45   f   1 ,  45   f   2 , thereby forming the ink chamber  45   g  and the first and second air chambers  45   h,    45   i.  Therefore, it is not necessary to constitute the ink chamber  45   g  by the bag-shaped ink pack. Accordingly, the ink chamber  45   g  can simply be constituted and a cost in the manufacture and assembly of the ink cartridge  45  can be reduced. 
         [0072]    Moreover, the air introducing port  45   n  and the ink lead-out port  45   m  are directly formed on the case  45   a . Consequently, the air can be directly introduced from the ink introducing port  45   n  into the first and second air chambers  45   h,    45   i  and the ink in the ink chamber  45   g  can be directly led out of the ink lead-out port  45   m  formed on the case  45   a.  Accordingly, it is not necessary to connect the case  45   a  to the first and second air chambers  45   h,    45   i  and ink chamber  45   g.  The seal member for connection is not required. For this reason, the ink cartridge  45  can have a simple structure. Therefore, it is possible to prevent an increase in a cost and an increase in the size of the apparatus. 
         [0073]    (2) In the first embodiment, the case  45   a  is partitioned by the films  45   f   1 ,  45   f   2 , thereby forming the ink chamber  45   g  and the first and second air chambers  45   h,    45   i.  The air generated by the air pump  33  is introduced into the first and second air chambers  45   h ,  45   i.  Accordingly, the flexible films  45   f   1 ,  45   f   2  are flexed by the pressurized air so that the ink in the ink chamber  45   g  can be pressurized. Also in the case in which the amount of the ink in the ink chamber  45   g  is small, therefore, the ink can be led out. 
         [0074]    (3) In the first embodiment, among six side faces forming the ink chamber  45   g,  the upper and lower side faces which have large surface area are formed with the film  45   f   1 ,  45   f   2 , and the other four side faces are formed with the case  45   a  (more specifically, the inner case  45   a   2 ) That is, the area forming the ink chamber  45   g  with the case  45   a  (inner case  45   a   2 ) made of plastic resin with low gas barrier property is lowered as much as possible, so that the area forming the ink chamber  45   g  with the films  45   f   1 ,  45   f   2  with high gas barrier property becomes large. Therefore, the ink chamber  45   g  with high degree of deaeration is formed. 
         [0075]    In particular, in the embodiment, each of the films  45   f   1 ,  45   f   2  is constituted by laminating polypropylene, gas barrier layer, nylon and the like. The outer layer is made of polypropylene as a material weldable to the film welding portions  45   d   1 ,  45   d   2 . The high gas barrier property can be secured by using films containing a layer of metal such as aluminum which yields good performance as the gas barrier layer. Nylon is formed on the gas barrier layer for protection. 
         [0076]    (4) In the first embodiment, the inside of the case  45   a  is partitioned into the ink chamber  45   g  and the first and air chambers  45   h  and  45   i  by the two films  45   f   1 ,  45   f   2 , and the ink chamber  45   g  is interposed between the two air chambers  45   h  and  45   i.  Also in the case in which the amount of the ink in the ink chamber  45   g  is decreased, therefore, the air can be introduced into each of the air chambers  45   h  and  45   i  to flex each film  45   f   1 ,  45   f   2 . Also in the case in which the amount of the ink in the ink chamber  45   g  is small, accordingly, it is possible to flex the films  45   f   1 ,  45   f   2 , thereby pressurizing the ink in the ink chamber  45   g  to lead out the ink. Particularly, in a case that films  45   f   1 ,  45   f   2  with high gas barrier property, which are generally less flexible than other films for the partitioning member, are used, the total flex amount of the ink chamber  45   g  can be obtained sufficiently large by providing the films on both of upper and lower face, thereby reducing the residual ink. Therefore, the remaining ink which is not utilized can be reduced while keeping degree of deaeration. 
         [0077]    (5) In the first embodiment, each film  45   f   1 ,  45   f   2  is thermally welded to each film welding portion  45   d   1 ,  45   d   2 , and the lids  45   b  and  45   c  are vibrated and welded to the lid welding portions  45   e   1 ,  45   e   2  protruded from the film welding portions  45   d   1 ,  45   d   2 . For this reason, the sealing properties of the ink chamber  45   g  and each off the air chambers  45   h  and  45   i  can be enhanced, and furthermore, the air chambers  45   h  and  45   i  can be provided on both sides of the ink chamber  45   g  with a simple structure. 
         [0078]    (6) In the first embodiment, the first connecting portion  45   j  and the second connecting portion  45   k  are formed on one of the side faces of the case  45   a,  and the ink lead-out port  45   m  and the air introducing port  45   n  penetrate, respectively. Therefore, it is also possible to cope with the case in which the ink is led out or the air is introduced from the side face of the ink cartridge  45  provided in the printer body  11 . 
       Second Embodiment 
       [0079]    Next, a second embodiment according to the invention will be described with reference to  FIG. 6 . In the second embodiment, the structure of the ink cartridge according to the first embodiment is only changed. Therefore, the detailed description of the same portions will be omitted. 
         [0080]      FIG. 6  is a sectional view showing an ink cartridge  49  taken along an IV-IV line in  FIG. 3 , illustrating the case in which covering with an outer film  49   b  and a protecting lid  49   h  is carried out. The ink cartridge  49  includes a case  49   a  taking the shape of a rectangular parallelepiped in which an upper face is opened. 
         [0081]    A film welding portion  49   c  and a lid welding portion  49   d  are protruded from the case  49   a  formed of polypropylene. The welding portion  49   c  is formed like a square frame, and the lid welding portion  49   d  is formed like a square frame in order to surround the film welding portion  49   c . Furthermore, the lid welding portion  49   d  is formed to be higher than the film welding portion  49   c.    
         [0082]    When an inner film  49   e  is thermally welded to the film welding portion  49   c,  an ink chamber  49   f  to be an ink storage part is formed by the inner film  49   e  and the bottom and side faces of the case  49   a.  When an outer film  49   b  to be a lid member is thermally welded to the lid welding portion  49   d  in a state in which the inner film  49   e  is welded to the film welding portion  49   c,  furthermore, an air chamber  49   g  is formed above the ink chamber  49   f  by the outer film  49   b,  the inner film  49   e  and the side face of the case  49   a.  Accordingly, the ink chamber  49   f  and the air chamber  49   g  are formed by thermally welding the inner film  49   e  and the outer film  49   b  in the same manner. Consequently, a step of assembling the ink cartridge  49  can be prevented from being complicated. 
         [0083]    After the outer film  49   b  is welded to the lid welding portion  49   d,  the upper face of the case  49   a  is covered with the protecting lid  49   h.  The protecting lid  49   h  is formed by a synthetic resin and has a bottom, and is formed in such a manner that the end of a side face is bent inward. The bent end can be sealed with a protruded portion  49   i  protruded horizontally from the case  49   a  under the lid welding portion  49   d.  For this reason, the protecting lid  49   h  can be prevented from slipping from the case  49   a.    
         [0084]    According to the second embodiment, it is possible to obtain the following advantages in addition to the same advantages as those of the (1), (2) and (6) described in the first embodiment. 
         [0085]    (7) In the second embodiment, the outer film  49   b  is thermally welded to the lid welding portion  49   d  in a state in which the inner film  49   e  is welded to the film welding portion  49   c.  Accordingly, the ink chamber  49   f  and the air chamber  49   g  are formed by thermally welding the inner film  49   e  and the outer film  49   b  in the same manner. Therefore, a step of assembling the ink cartridge  49  can be prevented from being complicated. 
         [0086]    (8) Further, in the second embodiment, the thermal welding does not yield any chips as in vibration welding and there is no fear that foreign substances are adhered on the welding portions. Moreover, the thermal welding to the welding portions of the case  49   a  having large openings is relatively easy as compared to the vibration welding. Therefore, the ink cartridge  49  having large capacity can be manufactured in an easy and simple manner. 
         [0087]    (9) In the second embodiment, the outer film  49   b  is welded to the lid welding portion  49   d  and the upper face of the case  49   a  is then covered with the protecting lid  49   h.  Consequently, the outer film  49   b  can be prevented from being broken. 
         [0088]    In the second embodiment, the film  49   b  also serves as a lid of the case  49   a  by sealing the case  49   a  to form the air chamber  49   g.  Therefore, there is no need to weld the protecting lid  49   h  to the case  49   a  by vibration welding or the like, and selection of material for the protecting lid  49   h  is not restricted. Accordingly, the material for the protecting lid  49   h  can be freely selected in a suitable manner in a case that importance is placed on the appearance of the ink cartridge  49 . 
       Third Embodiment 
       [0089]    Next, a third embodiment according to the invention will be described with reference to  FIGS. 7 to 9 . The third embodiment is directed to a connecting portion of the cartridge. Therefore, the detailed description of the same portions will be omitted. 
         [0090]      FIG. 7  is a plan view showing an ink cartridge  50  according to the embodiment as seen from above.  FIG. 8  is a sectional view showing the ink cartridge  50  taken along a VIII-VIII line in  FIG. 7 , and  FIG. 9  is a sectional view showing the ink cartridge  50  taken along an IX-IX line in  FIG. 7 .  FIGS. 8 and 9  show the case in which a case  50   a  is covered with a lid  50   b.  The ink cartridge  50  includes a case  50   a  taking the shape of a rectangular parallelepiped which has an upper face opened, and the case  50   a  is sealed by covering the opening portion with the lid  50   b.    
         [0091]    A film welding portion  50   c  and a lid welding portion  50   d  are protruded from the case  50   a  formed of polypropylene. The film welding portion  50   c  is formed like a square frame, and the lid welding portion  50   d  is formed like a square frame in order to surround the film welding portion  50   c . Furthermore, the lid welding portion  50   d  is formed to be higher than the film welding portion  50   c.    
         [0092]    On the other hand, when a film  50   e  is thermally welded to the film welding portion  50   c,  an ink chamber  50   f  is formed by the film  50   e  and the bottom and side faces of the case  50   a.  When the lid  50   b  formed by the same material as the material of the case  50   a  is vibrated and welded to the lid welding portion  50   d,  moreover, an air chamber  50   g  is formed by the lid  50   b,  the side face of the case  50   a  and the film  50   e.  Moreover, a first connecting portion  50   h  for fitting and inserting a supply needle connected to an ink supply tube  34  is protruded from the bottom face of the case  50   a.  An ink lead-out port  50   i  communicating with the ink chamber  50   f  penetrates through the first connecting portion  50   h  and the bottom face of the case  50   a  on which the first connecting portion  50   h  is formed. 
         [0093]    Moreover, a second connecting portion  50   j  for connecting an air supply tube  29  is formed on the bottom face on which the first connecting portion  50   h  is formed. As shown in  FIG. 9 , an air introducing port  50   k  communicating with the air chamber  50   g  penetrates through the second connecting portion  50   j  and a side face on which the second connecting portion  50   j  is formed. The air introducing port  50   k  is constituted by a hole penetrating toward the air chamber  50   g  in a vertical direction in the drawing, and supplies the pressurized air fed from an air pump  33  to the air chamber  50   g  formed above the ink chamber  50   f.    
         [0094]    In the ink lead-out port  50   i  and the air introducing port  50   k,  thus, the first connecting portion  50   h  and the second connecting portion  50   j  are formed on the bottom face of the case  50   a,  and can be therefore opened on the bottom face of the case  50   a.  Consequently, it is also possible to cope with the case in which an ink or the air fed from the air pump  33  is to be led out of or introduced into the bottom face of the case  50   a.  Moreover, the ink cartridge  50  can be provided in such a manner that the bottom face of the case  50   a  is almost parallel with a right side plate  12   a  and a left side plate  12   b  in a frame  12 . In addition, the bottom face of the case  50   a  can be provided to be a lower face. 
         [0095]    According to the third embodiment, it is possible to obtain the following advantages in addition to the same advantages as those of the (1) and (2) described in the first embodiment. 
         [0096]    (11) In the third embodiment, the first connecting portion  50   h  and the second connecting portion  50   j  are formed on the bottom face of the case  50   a,  and the ink lead-out port  50   i  and the air introducing port  50   k  penetrate and are opened at the bottom face of the case  50   a,  respectively. Consequently, the ink cartridge  50  can be caused to cope with the case in which the air is to be introduced into or the ink is to be led out of the bottom face of the case  50   a  corresponding to a position in which the ink cartridge  50  is provided and a position of the air pump  33 . Accordingly, it is possible to enhance the degree of freedom of the design of the printer body 
         [0097]    Each of the embodiments may be changed as follows.
       While the four ink cartridges  45  to  48  are provided in each of the embodiments, the number of the ink cartridges mounted on the printer body  11  may be optional.   In each of the embodiments, the bottom face of the case and the lid in the ink cartridges  45  to  48  are provided in the printer body  11  in almost parallel with the right side plate  12   a  and the left side plate  12   b  in the frame  12 . In addition, the ink cartridges  45  to  48  may be provided in any direction, for example, the bottom face of the case is provided to be a lower face.   In the embodiments, the films  45   f   1 ,  45   f   2  and  50   e  or the inner film  49   e  may be thermally welded so as to partition the case in a loose state as in the second embodiment. Thus, the films  45   f   1 ,  45   f   2  and  50   e  or the inner film  49   e  can be flexed to pressurize the ink even if the amount of the ink is very small. Moreover, the bottom or side faces of the ink chambers  45   g,    49   f  and  50   f  may be curved so as to coincide with the shape of the flexed film. Thus, the ink can be prevented from remaining in the corner portions of the ink chambers  45   g ,  49   f  and  50   f.  Consequently, the lead-out property of the ink can be enhanced more greatly.   In the first, and third embodiments, the lids  45   b ,  45   c  and  50   b  may be constituted by a film as shown in the second embodiment, and furthermore, may be covered with a protecting lid as in the fourth embodiment. Thus, a step of assembling the ink cartridges  45  and  50  can be prevented from being complicated.   In the second embodiment, the first connecting portion  49   j  may be formed on the bottom faces of the cases as in the third embodiment. Thus, the ink lead-out port  49   k  or the air introducing port (not shown) can be opened at the bottom face. Consequently, it is possible to enhance the degree of freedom of the design of the printer body  11 .   While the films  45   f   1 ,  45   f   2  are constituted by laminating polypropylene, gas barrier layer, nylon and the like in the above embodiments, the film may be formed with a two-layer structure in a case that a gas barrier layer is provided with a material inactive to environment. For example, a film having two-layer structure constituted by propylene as welding layer and EVOH resin (ethylene-vinyl alcohol copolymer) as gas barrier layer may be served as the flexible films of the invention.   While the liquid ejecting apparatus is used in the ink jet printer in each of the embodiments, it may be applied to a liquid ejecting apparatus for injecting a liquid other than an ink. For example, it is also possible to employ a liquid ejecting apparatus for injecting a liquid such as an electrode material or a coloring material to be used in the manufacture of a liquid crystal display, an EL display or an FED (face emitting display), a liquid ejecting apparatus for injecting a biological organic matter to be used in the manufacture of a biochip, and a sample injecting apparatus to be a precision pipette.