Abstract:
An ink container detachably mountable to a portion to be mounted includes a substantially prism-shaped casing having an opening, a multi-layer inner bladder deformable with discharge of liquid, the inner bladder having an outer surface which is equivalent or similar to an inner surface of the casing, the casing and the inner bladder constituting a liquid reservoir, and a discrimination member for discriminating the liquid in the liquid reservoir.

Description:
FIELD OF THE INVENTION AND RELATED ART 
     The present invention relates to an ink container for an ink jet recording apparatus or the like, a valve unit for an ink container, a method for manufacturing an ink container, an ink jet head cartridge comprising an ink container, and an ink jet recording apparatus. In particular, it relates to an innovative ink container formed with the use of blow molding. 
     Among conventional ink jet recording apparatuses, some comprise a recording head which records on recording medium by ejecting ink, an ink container which contains ink to be supplied to the recording head, and an ink container holder as a portion which removably holds the ink container. The ink container holder also has the recording head. An ink jet recording apparatus capable of recording in color, that is, a color printer, comprises such an ink container holder that has a recording head for magenta color, a recording head for yellow color, a recording head for cyan color, and a recording head for black color, and is structured so that an ink container correspondent to each of the recording heads can be removably mounted in the ink container holder, to a position specified for each color. 
     There have been conceived various functions for preventing installation mistakes, so that an ink container correspondent to each of the plurality of recording heads is properly mounted to a position specified in the ink container holder in a color printer such as the one described above. 
     According to the first of such methods, the holder position specified for each of the different inks is labeled so that a user can visually confirm the correct holder position, or so that after ink container installation, any irregularity in ink container position is detected and a warning is displayed. 
     According to the second of such methods, each ink container, depending on the color of the ink it contains, is varied in the shape of the joint portion, at which each ink container is connected to the correspondent recording head as each ink container is mounted in the holder, so that installation mistakes are prevented. 
     According to the third of such methods, the external surface of each ink container is provided with a projection, the shape or structure of which is made different from those of the other ink containers different in ink color, and the ink container holder is provided with indentations or grooves in which the projections fit, and which are matched in shape or structure to the correspondent ink containers so that installation mistakes can be prevented. 
     In recent years, various advancements have been made in the field of an ink jet printer; it has become possible to print high quality images with the use of an ink jet printer, and also to use various types of ink. It has been known that the resistance of an image to water or friction can be improved by using two inks of different type so that the two inks solidify and fix to a sheet of recording medium by reacting to each other. Should an ink container be installed to a wrong position when this kind of method is employed, a recording head will be seriously damaged in function and the recorded images will be quite inferior. Thus, it is required that an ink container to be removably mounted in an ink container holder is provided with a highly precise and reliable identification structure, and also that the ink container is provided with a leak-proof ink outlet (with durability). 
     The above described conventional installation mistake prevention methods, however, had the possibility of suffering from problems. For example, in the case of the first example, an installation mistake was caught after the installation, and therefore, it was possible that inks were mixed and solidified, causing various problems: ink ejecting holes were plugged; ink failed to be ejected; a portion or portions of a printed image were missing; and a printer sustained various types of damage. In addition, it was possible that in the case of an apparatus which employs an exchangeable type ink container, ink containers were unnecessarily exchanged with fresh ones. 
     In the case of the second example, it did not occur that an ink container was installed all the way to a wrong position, but before an installation mistake was caught, the joint portions were placed in contact with each other. Therefore, it was also possible that the inks would mix and solidify, causing various problems, that is, ejection failure, printing of images with a missing portion or portions, and apparatus breakage. Also in this case, there was a possibility that in the case of an apparatus which employs an exchangeable type ink container, ink containers were unnecessarily exchanged with fresh ones. 
     In the case of the third example, an installation mistake was physically prevented, which reduced the possibility of ink mixture such as the one described above. However, the ink container shape was complicated, in particular, when an ink container provided with an identification structure was formed in a single piece. Therefore, there were problems that the ink container cost was high, and also that an ink container was limited in terms of material. 
     Various publications, in particular, EP0738605, disclose an ink container which is formed by blow molding. This ink container comprises a hard external shell in the form of an approximately polygonal prism, and a liquid holding portion (hereinafter, it may be referred to as “internal bladder”) which holds liquid therein. When the liquid holding portion is full, it is virtually identical, or very similar, in shape to the internal space of the shell. It changes in shape as the liquid therein is drawn out. Hereinafter, this type of an ink container may be referred to as multilayer container. As described in the aforementioned publications, it is excellent in terms of ink storage ratio, and also the ink usage ratio. However, there is a possibility that various problems will occur as its shape becomes complicated. 
     To begin with, it is generally difficult to form a highly precise object with the use of blow molding; it is difficult to form a precise and reliable identification structure on an ink container. 
     Further, as the ink is drawn out of the ink holding portion of the aforementioned ink container, the ink holding portion must properly shrink so that the liquid is supplied out of the ink holding portion while generating negative pressure therein. The shape of the internal bladder corresponds to the shape of the ink container external shell, and therefore, if the shell shape is complicated because of the presence of the irregularities on the surface of the shell, it is difficult for the internal bladder to deform as the ink is drawn out, and if the internal bladder fails to properly deform, the ink fails to be reliably supplied. In other words, there is a possibility that the ink cannot be reliably supplied from an ink container such as the aforementioned one, and in the case that the shell shape is more complicated, there is a possibility that pin holes may develop in the wall of the internal bladder. 
     On the other hand, it is desired that in the case of an ink jet head cartridge structured so that ink containers can be removably connected to the recording head portion of the ink jet head cartridge as described above, the joint portion between the ink container and the recording head portion, to which the liquid in an ink container is supplied, simultaneously satisfies at least the following requirements. 
     One of the requirements is that when an ink storing (or accommodating) container or is connected to, or separated from, to a component to which ink is to be supplied, ink does not leak from the joint portion regardless of the attitude of the ink storing container. Another of the requirements is that the ink can be steadily supplied after the completion of the connection. An additional requirement, which is necessary in consideration of the possibility that some users may repeat the processes of connecting and separating, is that the preceding two requirements, which must be satisfied when the connection or separation occurs, must be satisfied in spite of the repetition of the connecting and separating processes. 
     Thus, the inventors of the present invention paid attention to a means for sealing the joint opening of an ink container, more specifically, a valve mechanism which opens or closes the joint opening, in particular, such a valve mechanism that keeps the joint opening sealed when the ink container is not in connection to the ink jet head cartridge, and opens the joint opening as the joint pipe of the liquid receiving party is pushed into the ink outlet of the ink container, and that returns to its original position, or sealing position, to seal the joint opening as the joint pipe is separated from the joint opening. 
     However, the assumption of the installation of a valve mechanism unit in the liquid outlet of a liquid container led to the discovery of a fresh technical problem that if the valve mechanism is exposed from the liquid container, the valve mechanism drops out of the liquid outlet or becomes dislocated in the liquid outlet due to external causes, for example, when the liquid container is dropped. 
     SUMMARY OF THE INVENTION 
     The primary object of the present invention is to provide an ink container, in the form of the aforementioned multilayer container which is superior in liquid storage ratio and usage ratio, and is provided with an inexpensive and reliable mechanism for preventing installation mistakes, without negatively affecting the advantage of the multilayer container, that is, the stability in the negative pressure when the ink container is in use. 
     The second object of the present invention is related to, solely or in addition to the above described first object, an ink container having an installation mistake prevention mechanism which comprises a valve placed in the ink delivery opening portion, and to provide an ink container which does not suffer from the aforementioned new technical problems regarding an ink container having a valve in the ink delivery opening portion. 
     The third object of the present invention is related to, solely or in addition to the above described first object, an ink container having a valve in the ink delivery opening portion, and is to provide an ink container which assures that liquid does not uselessly leak from the valve unit and opening portion. 
     The remaining object of the present invention is to provide various inventions related to the valve unit usable in the above described ink container, an ink container manufacturing method, an ink jet head cartridge in which the ink container is mounted, an ink jet recording apparatus, and the like. 
     The ink container in accordance with the present invention is characterized in that in order to accomplish the aforementioned first object, it is removably mountable into or onto a dedicated installation space, and that it comprises: an liquid storing member comprising an external shell, which has an opening and is in the form of an approximately polygonal prism, and an internal multilayer bladder, which is virtually identical, or very similar, in shape to the internal space of the shell, and is capable of deforming as the liquid stored therein is drawn out; and an identification member for identifying the type of liquid in the liquid storing member. 
     Since the aforementioned ink container comprises the liquid storing member for storing liquid, and the identification member for identifying the liquid in the liquid storing member, when manufacturing a plurality of ink containers for inks of different color, the liquid storing member may be manufactured as a common component. This reduces cost. Separating the ink container into two subsections, that is, the identification member and the liquid storing portion, makes it possible to form the liquid storing portion, namely, a container with a multilayer wall, with the use of multilayer blow molding, and the identification member, which requires a higher degree of dimensional accuracy, with the use of injection molding. Therefore, it is possible to realize an ink container which guarantees more stable ink delivery, and more accurate identification, compared to a container which is provided with the identification function, and is formed as a single piece component. 
     The ink container in accordance with the present invention is characterized in that in order to accomplish the aforementioned second object, it comprises a liquid storing member, which has an opening portion for drawing ink out as well as storing ink, and an identification member for identifying the liquid in the liquid storing member, and which is removably installable into or onto a dedicated installation space, and the valve unit, which allows the liquid in the liquid storing member to be drawn out, and is located in the opening portion of the liquid storing member; that the identification member is provided with an ink delivery opening, which covers the joint portion between the valve unit and liquid storing member, and is located adjacent to the periphery of the liquid path of the valve unit; and that the identification member is almost immovably but removably fixed to the liquid storing member with the use of a joining means which allows the former to be easily disjoined from the latter. 
     According to the above described ink container, the identification member can be used as the cover for protecting the valve unit and opening portion, and the identification member and liquid storing member are joined to each other with the use of a method which allows the former to be easily disjoined from the latter. Therefore, the valve unit and opening portion are not subjected to excessive force. Therefore, it is possible to provide an ink container which does not suffer from the new problems of the container equipped with a valve, that is, such a problem that the valve mechanism drops out or shifts due to falling or other external influences. 
     The ink container in accordance with the present invention is characterized in that in order to accomplish the above, it has a valve unit for supporting the valve mechanism which can be opened or closed, in the ink delivery opening portion, and the protective cover for protecting the joint portion between the valve unit and the main assembly of the ink container, is positioned adjacent to the periphery of the liquid path of the valve unit. 
     According to the above described ink container, the valve mechanism is effectively prevented from dropping out or shifting by the protective cover, and the occurrence of a fresh leak is prevented by the contact area between the valve mechanism and protective cover, which are unitized with each other as the protective cover is attached. As a result, it is possible to provide an ink container which assures that the useless liquid leakage from the valve unit and opening portion can be prevented. 
     The valve unit in accordance with the present invention is characterized in that it comprises: a cylindrical valve body (or frame); a valve plug (or member) in the form of a piston which freely slides in the valve body; a supporting member which is joined to the one end of the valve body, and supports a portion of the valve plug in a manner to allow the plug to freely slide; a resilient member for generating constant force in the direction to push the valve plug away from the supporting member; a contact portion which is located along the inwardly facing surface of the valve body, and makes contact with the end of the valve plug under the pressure from the resilient member; an elastomer layer, which is placed on the interior surface of the valve body, covering from the position of the aforementioned contact portion to the other end of the valve body, and the portion of which constitutes the aforementioned contact portion; an opening which becomes disconnected from the opening on another end of the valve body as the end of the valve plug comes into contact with the aforementioned contact portion; and a flange which radially extends from the periphery of the other end of the valve body, wherein the position of the plane of the front surface of the flange is different from the plane of the opening of the valve body, on the flange side. 
     According to the above described valve unit, the opening end of the valve body, on the liquid delivery opening side, is made to project from the surface of the flange, and therefore, when the peripheral portion of the opening of the protective cover of the ink container is joined to the flange, the open end of the valve body can be positioned in the aforementioned opening portion. As a result, the elastomer layer which was placed on the inward surface of the valve body is exposed at the inward side of the opening of the aforementioned external protective member; in other words, the area coated with the elastomer layer is expanded onto the periphery of the aforementioned liquid delivery pipe, turning the valve mechanism into a highly reliable one which does not allow liquid to leak when liquid is supplied through the aforementioned liquid delivery pipe. 
     The ink container manufacturing method in accordance with the present invention is characterized in that it is a method for manufacturing an ink container comprising: a liquid storing member which stores liquid and is provided with an opening for drawing out the liquid therein, a valve unit placed in the opening of the liquid storing member, and an identification member which is used for identifying the type of the liquid in the liquid storing member and is provided with an ink delivery portion which covers the opening of the ink storing member, and that it comprises: a fixing process for fixing the valve unit to the liquid storing member, and a joining process for joining the liquid storing member to the identification member with the use of a joining means which allows the former to be easily disjoined from the latter, after the valve unit is fixed to the liquid storing member. 
     According to the above described ink container manufacturing method, the ink container for accomplishing the second object of the present invention can be easily manufactured. 
     The present invention is also related to an ink jet head cartridge and an ink jet recording apparatus, in which the above described ink container is mounted. 
     The ink jet head cartridge in accordance with the present invention is characterized in that it comprises a space into which the above described ink container is removably installable, and a recording head portion for ejecting the liquid in the ink container installed in the above ink container space, and that it comprises an identifying portion for identifying the identification member with which the ink container is provided. 
     The ink jet recording apparatus in accordance with the present invention is characterized in that it comprises the above described ink jet head cartridge, and a moving means for moving the ink jet head cartridge and recording medium relative to each other, and that it can record on the recording medium by ejecting ink from the recording head in response to electrical signals for ejecting the liquid. 
     These and other objects, features, and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the ink jet head cartridge in one of the embodiments of the present invention. 
     FIG. 2 is a sectional view of the cartridge in FIG.  1 . 
     FIG. 3 is a perspective drawing for depicting the ink container unit illustrated in FIG.  2 . 
     FIG. 4 is a sectional drawing for depicting the operation for attaching the ink container unit to a holder to which the negative pressure controlling chamber unit illustrated in FIG. 2 has been attached. 
     FIG. 5 is a sectional drawing for depicting the opening and closing operations of the valve mechanism to which the present invention is applicable. 
     FIG. 6 is a sectional drawing for depicting the operation for supplying the ink jet head cartridge illustrated in FIG. 2, with ink. 
     FIG. 7 is a graph for depicting the state of the ink during ink consumption, with reference to FIG.  6 . 
     FIG. 8 is a graph for depicting the effect of the change in the internal pressure resulting from the deformation of the internal bladder during the ink consumption in the ink jet head cartridge shown in FIG.  6 . 
     FIG. 9 is a sectional drawing for depicting the relationship between the valve body and valve plug in the valve mechanism to which the present invention is applicable. 
     FIG. 10 is a perspective view of an example of the shape of the end portion of the joint pipe which engages with the valve mechanism when the valve mechanism is opened or closed, and to which the present invention is applicable. 
     FIG. 11 is a sectional drawing for depicting an example of a valve mechanism, which is to be compared with the valve mechanism in accordance with the present invention. 
     FIG. 12 is a sectional drawing for depicting the state of twisting in the valve mechanism illustrated in FIG.  11 . 
     FIG. 13 is a sectional drawing for depicting how the liquid outlet is sealed by the valve mechanism illustrated in FIG.  11 . 
     FIG. 14 is a sectional drawing for depicting the valve mechanism in accordance with the present invention. 
     FIG. 15 is a sectional drawing for depicting the state of twisting in the valve mechanism illustrated in FIG.  14 . 
     FIG. 16 is a sectional drawing for depicting how the liquid outlet is sealed by the valve mechanism illustrated in FIG.  14 . 
     FIG. 17 is a schematic drawing for depicting how the valve plug of the valve mechanism illustrated in FIG. 14 engages with the end portion of the joint pipe. 
     FIG. 18 is a sectional drawing for depicting the method for manufacturing an ink storing container in accordance with the present invention. 
     FIG. 19 is a sectional view of the ink storing container illustrated in FIG. 2, for depicting an example of the internal structure of the ink container. 
     FIG. 20 is a schematic drawing for depicting the absorbent material in the negative pressure controlling chamber shell illustrated in FIG.  2 . 
     FIG. 21 is also a schematic drawing for depicting the absorbent material in the negative pressure controlling chamber shell illustrated in FIG.  2 . 
     FIG. 22 is a schematic drawing for depicting the rotation of the ink container unit illustrated in FIG. 2, which is caused when the ink container unit is installed or removed. 
     FIG. 23 is a schematic perspective view of an ink jet head cartridge compatible with the ink container unit in accordancel with the present invention. 
     FIG. 24 is a schematic perspective view of a recording apparatus compatible with the ink jet head cartridge in accordance with: the present invention. 
     FIG. 25 is a sectional view of the ink container unit, for giving the measurements of the structural components which constitute the joint portion of the ink container unit in accordance with the present invention. 
     FIG. 26 is a drawing for depicting the first modified version of the structure in accordance with the present invention, for almost immovably fixing the ink container and ID member of an ink container, to each other. 
     FIG. 27 is a drawing for depicting the second modified version of the structure in accordance with the present invention, for almost immovably fixing the ink container and ID member of an ink container, to each other. 
     FIG. 28 is a perspective drawing for depicting the assembly process of the ink container illustrated in FIG.  24 . 
     FIG. 29 is a drawing for depicting another modified version of the structure in accordance with the present invention, for almost immovably fixing the ink container and ID member of an ink container, to each other. 
     FIG. 30 is a drawing for depicting another modified version of the structure in accordance with the present invention, for almost immovably fixing the ink container and ID member of an ink container, to each other. 
     FIG. 31 is a sectional view of the ink jet head cartridge in another embodiment of the present invention. 
     FIG. 32 is a perspective drawing for depicting the ink container unit illustrated in FIG.  31 . 
     FIG. 33 is a sectional drawing for depicting the another method for manufacturing an ink container in accordance with the present invention. 
     FIG. 34 is a schematic sectional view of an ink jet head cartridge which is holding the ink container in another embodiment of the present invention. 
     FIG. 35 is a schematic sectional view of an ink jet head cartridge which is holding the ink container in another embodiment of the present invention. 
     FIG. 36 is a perspective drawing for depicting the ink container in another embodiment of the present invention. 
     FIG. 37 is an enlarged sectional view of the ink container illustrated in FIG. 36, when the ink container is in connection with the head cartridge. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, the embodiments of the present invention will be described with reference to the appended drawings. 
     In the following description of the embodiments of the present invention, “hardness” of a capillary force generating portion means the “hardness” of the capillary force generating portion when the capillary force generating member is in the liquid container. It is defined by the inclination of the amount of resiliency of the capillary force generating member relative to the amount of deformation. As for the difference in hardness between two capillary force generating members, a capillary force generating member which is greater in the inclination in the amount of resiliency relative to the amount of deformation is considered to be “harder capillary force generating member”. 
     &lt;General Structure&gt; 
     FIG. 1 is a perspective view of the ink jet head cartridge in the first of the embodiments of the present invention, and FIG. 2 is a sectional view of the same ink jet head cartridge. 
     In this embodiment, each of the structural components of the ink jet head cartridge in accordance with the present invention, and the relationship among these components, will be described. Since the ink jet head cartridge in this embodiment was structured so that a number of innovative technologies, which were developed during the making of the present invention, could be applied to the ink jet cartridge which was being invented, the innovative structures will also be described as the overall description of this ink jet head cartridge is given. 
     Referring to FIGS. 1 and 2, the ink jet head cartridge in this embodiment comprises an ink jet head unit  160 , a holder  150 , a negative pressure controlling chamber unit  100 , an ink container unit  200 , and the like. The negative pressure controlling chamber unit  100  is fixed to the inward side of the holder  150 . Below the negative pressure controlling chamber unit  100 , the ink jet head is attached to the outward side of the bottom wall portion of the holder  150 . Using screws or interlocking structures, for ease of disassembly, to fix the negative pressure controlling chamber unit  100  and ink jet head unit  160  to the holder  150  is desirable in terms of recycling, and also is effective for reducing the cost increase which is incurred by the structural modification or the like. Further, since the various components are different in the length of service life, the aforementioned ease of disassembly is also desirable because it makes it easier to replace only the components which need to be replaced. It is obvious, however, that they may be permanently connected to each other by welding, thermal crimping, or the like. The negative pressure controlling chamber unit  100  comprises: a negative pressure controlling chamber shell  110 , which is open at the top; a negative pressure controlling chamber cover  120  which is attached to the top portion of the negative pressure controlling chamber shell  110  to cover the opening of the negative pressure controlling chamber shell  110 ; two pieces of absorbent material  130  and  140  which are placed in the negative pressure controlling chamber shell  110  to hold ink by impregnation. The absorbent material pieces  130  and  140  are filled in vertical layers in the negative pressure controlling chamber shell  110 , with the absorbent material piece  130  being on top of the absorbent material piece  140 , so that when the ink jet head cartridge is in use, the absorbent material pieces  130  and  140  remain in contact with each other with no gap between them. The capillary force generated by the absorbent material piece  140 , which is at the bottom, is greater than the capillary force generated by the absorbent material piece  130  which is at the top, and therefore, the absorbent material piece  140  which is at the bottom is greater in ink retainment. To the ink jet head unit  160 , the ink within the negative pressure controlling chamber unit  100  is supplied through an ink supply tube  165 . 
     The opening  131  of the ink supply tube  160 , on the absorbent material piece  140  side, is provided with a filter  161 , which is in contact with the absorbent material piece  140 , being under the pressure from the elastic member. The ink container unit  200  is structured so that it can be removably mounted in the holder  150 . A joint pipe  180 , which is a portion of the negative pressure controlling chamber shell  110  and is located on the ink container unit  200  side, is connected to the joint opening  230  of the ink container unit  200  by being inserted thereinto. The negative pressure controlling chamber unit  100  and ink container unit  200  are structured so that the ink within the ink container unit  200  is supplied into the negative pressure controlling chamber unit  100  through the joint portion between the joint pipe  180  and joint opening  230 . Above the joint pipe  180  of the negative pressure controlling chamber shell  110 , on the ink container unit  200  side, there is an ID member  170  for preventing the ink container unit  200  from being incorrectly installed, which projects from the surface of the holder  150 , on the ink container unit  200  side. 
     The negative pressure controlling chamber cover  120  is provided with an air vent  115  through which the internal space of the negative pressure controlling chamber shell  110  is connected to the outside; more precisely, the absorbent material piece  130  filled in the negative pressure controlling chamber shell  110  is exposed to the outside air. Within the negative pressure controlling chamber shell  110  and adjacent to the air vent, there is a buffering space  116 , which comprises an empty space formed by a plurality of ribs projecting inwardly from the inward surface of the negative pressure controlling chamber cover  120 , on the absorbent material piece  130  side, and a portion of the absorbent material piece  130 , in which no ink (liquid) is present. 
     On the inward side of the joint opening  230 , a valve mechanism is provided, which comprises a first valve body (or frame)  260   a , a second valve body  260   b , valve plug (or member)  261 , a valve cover (or cap)  262 , and a resilient member  263 . The valve plug  261  is held within the second valve body  260   b , being allowed to slide within the second valve body  260   b  and also being kept under the pressure generated toward the first valve body  260   a  by the resilient member  263 . Thus, unless the joint pipe  180  is inserted through the joint opening  230 , the edge of the first valve plug  261 , on the first valve body  260   a  side, is kept pressed against the first valve body  260   a  by the pressure generated by the resilient member  263 , and therefore, the ink container unit  200  remains airtightly sealed. 
     As the joint pipe  180  is inserted into the ink container unit  200  through the joint opening  230 , the valve plug  261  is moved by the joint pipe  180  in the direction to separate it from the first valve body  260   a . As a result, the internal space of the joint pipe  180  is connected to the internal space of the ink container unit  200  through the opening provided in the side wall of the second valve body  260   b , breaking the airtightness of the ink container unit  200 . Consequently, the ink container unit  200  begins to be supplied into the negative pressure controlling chamber unit  100  through the joint opening  230  and joint pipe  180 . In other words, as the valve on the inward side of the joint opening  230  opens, the internal space of the ink holding portion of the ink container unit  200 , which remained airtightly sealed, becomes connected to the negative pressure controlling chamber unit  100  only through the aforementioned opening. 
     It should be noted here that fixing the ink jet head unit  160  and negative pressure controlling chamber unit  100  to the holder  150  with the use of easily reversible means, such as screws, as is done in this embodiment, is desirable because the two units  160  and  100  can be easily replaced as their service lives end. 
     More specifically, in the case of the ink jet head cartridge in this embodiment, the provision of an ID member on each ink container makes it rare that an ink container for containing one type of ink is connected to a negative pressure controlling chamber for an ink container for containing another type of ink. Further, should the ID member provided on the negative pressure controlling chamber unit  100  be damaged, or should a user deliberately connect an ink container to a wrong negative pressure controlling chamber unit  100 , all that is necessary is to replace only the negative pressure control chamber unit  100  as long as it is immediately after the incident. Further, if the holder  150  is damaged by falling or the like, it is possible to replace only the holder  150 . 
     It is desirable that the points, at which the ink container unit  200 , negative pressure controlling chamber unit  100 , holder  150 , and ink jet head unit  160 , are interlocked to each other, are chosen to prevent ink from leaking from any of these units when they are disassembled from each other. 
     In this embodiment, the ink container unit  200  is held to the negative pressure controlling chamber unit  100  by the ink container retaining portion  155  of the holder  150 . Therefore, it does not occur that only the negative pressure controlling chamber unit  100  becomes disengaged from the other units, inclusive of the negative pressure controlling chamber unit  100 , interlocked among them. In other words, the above components are structured so that unless at least the ink container unit  200  is removed from the holder  150 , it is difficult to remove the negative pressure controlling chamber unit  100  from the holder  150 . As described above, the negative pressure controlling chamber unit  100  is structured so that it can be easily removed only after the ink container unit  200  is removed from the holder  150 . Therefore, there is no possibility that the ink container unit  200  will inadvertently separate from the negative pressure controlling chamber unit  100  and ink leak from the joint portion. 
     The end portion of the ink supply tube  165  of the ink jet head unit  160  is provided with the filter  161 , and therefore, even after the negative pressure controlling chamber unit  100  is removed, there is no possibility that the ink within the ink jet head unit  160  will leak out. In addition, the negative pressure controlling chamber unit  100  is provided with the buffering space  116  (inclusive of the portions of the absorbent material piece  136  and the portions of the absorbent material piece  140 , in which no ink is present), and also, the negative pressure controlling chamber unit  100  is designed so that when the attitude of the negative pressure controlling chamber unit  100  is such an attitude that is assumed when the printer is being used, the interface  113   c  between the two absorbent material pieces  130  and  140 , which are different in the amount of the capillary force, is positioned higher than the joint pipe  180  (preferably, the capillary force generated at the interface  113   c  and its adjacencies becomes greater than the capillary force in the other portions of the absorbent material pieces  130  and  140 ). Therefore, even if the structural conglomeration comprising the holder  150 , negative pressure controlling chamber unit  100 , and ink container unit  200 , changes in attitude, there is very little possibility of ink leakage. Thus in this embodiment, the portion of the ink jet head unit  160 , by which the ink jet head unit  160  is attached to the holder  150 , is located on the bottom side, that is, the side where the electric terminals of the holder  150  are located, so that the ink jet head unit  160  can be easily removed even when the ink container unit  200  is in the holder  150 . 
     Depending upon the shape of the holder  150 , the negative pressure controlling chamber unit  100  or ink jet head unit  160  may be integral with, that is, inseparable from, the holder  150 . As for a method for integration, they may be integrally formed from the beginning of manufacture, or may be separately formed, and integrated thereafter by thermal crimping or the like so that they become inseparable. 
     Referring to FIGS. 2,  3 ( a ), and  3 ( b ), the ink container unit  200  comprises an ink storing or accommodating container or reservoir  201 , the valve mechanism comprising the first and second valve bodies  260   a  and  260   b , and the ID member  250 . The ID member  250  is a member for preventing installation mistakes which occur during the joining of ink container unit  200  to negative pressure controlling chamber unit  100 . 
     The valve mechanism is a mechanism for controlling the ink flow through the joint opening  230 , and is opened, or closed, as it is engaged with, or disengaged from, the joint pipe  180  of the negative pressure controlling chamber unit  100 , respectively. The misalignment, or twisting, of the valve plug, which tends to occur during the installation or removal of the ink container unit  200 , is prevented with the provision of an innovative valve structure, which will be described later, or the provision of an ID member  170  and an ID member slots  252 , which limit the rotational range of the ink container unit  200 . 
     &lt;Ink Container Unit&gt; 
     FIG. 3 is a perspective drawing for depicting the ink container unit  200  illustrated in FIG.  2 . FIG. 3, ( a ), is a perspective view of the ink container unit  200  in the assembled form, and FIG. 3, ( b ), is a perspective view of the ink container unit  200  in the disassembled form. 
     The front side of the ID member  250 , that is, the side which faces the negative pressure controlling chamber unit  100 , is slanted backward from the point slightly above the supply outlet hole  253 , forming a slanted (or tapered) surface  251 . More specifically, the bottom end, that is, the supply outlet hole  253  side, of the slanted surface  251  is the front side, and the top end, that is, the ink storing container  201  side, of the slanted surface  251  is the rear side. The slanted surface  251  is provided with a plurality of ID slots  252  (three in the case of FIG. 3) for preventing the wrong installation of the ink container unit  200 . Also in this embodiment, the ID member  250  is positioned on the front surface (surface with the supply outlet), that is, the surface which faces the negative pressure controlling chamber unit  100 , of the ink storing container  201 . 
     The ink storing container  201  is a hollow container in the form of an approximately polygonal prism, and is enabled to generate negative pressure. It comprises the external shell  210 , or the outer layer, and the internal bladder  220 , or the inner layer (FIG.  2 ), which are separable from each other. The internal bladder  220  is flexible, and is capable of changing in shape as the ink held therein is drawn out. Also, the internal bladder  220  is provided with a pinch-off portion (welding seam portion)  221 , at which the internal bladder  220  is attached to the external shell  210 ; the internal bladder  220  is supported by the external shell  210 . Adjacent to the pinch-off portion  221 , the air vent  222  of the external shell  210  is located, through which the outside air can be introduced into the space between the internal bladder  220  and external shell  210 ; 
     Referring to FIG. 19, the internal bladder  220  is a laminar bladder, having three layers different in function: a liquid contact layer  220   c , or the layer which makes contact with the liquid; an elastic modulus controlling layer  220   b ; and a gas barrier layer  220   a  superior in blocking gas permeation. The elastic modulus of the elastic modulus controlling layer  220   b  remains virtually stable within the temperature range in which the ink storing container  201  is used; in other words, the elastic modulus of the internal bladder  220  is kept virtually stable by the elastic modulus controlling layer  220   b  within the temperature range in which the ink storing container  201  is used. The middle and outermost layers of the internal bladder  220  may be switched in position; the elastic modulus controlling layer  220   b  and gas barrier layer  220   a  may be the outermost layer and middle layer, respectively. 
     Structuring the internal bladder  220  as described above makes it possible for the internal bladder  220  to synergistically display each of the individual functions of the ink-resistant layer  220   c , elastic modulus controlling layer  220   b , and gas barrier layer  220   a , while using only a small number of layers. Thus, the temperature sensitive properties, for example, the elastic modulus, of the internal bladder  220  is less likely to be affected by the temperature change. In other words, the elastic modulus of the internal bladder  220  can be kept within the proper range for controlling the negative pressure in the ink storing container  201 , within the temperature range in which the ink storing container  201  is used. Therefore, the internal bladder  220  is enabled to function as the buffer for the ink within the ink storing container  201  and negative pressure controlling chamber shell  110  (details will be given later). Consequently, it becomes possible to reduce the size of the buffering chamber, that is, the portion of the internal space of the negative pressure controlling chamber shell  110 , which is not filled with ink absorbing material, inclusive of the portion of the absorbent material piece  130 , in which ink is not present, and the portion of the absorbent material piece  140 , in which ink is not present. Therefore, it is possible to reduce the size of the negative pressure controlling chamber unit  100 , which in turn makes it possible to realize an ink jet head cartridge  70  which is superior in operational efficiency. 
     In this embodiment, polypropylene is used as the material for the liquid contact layer  220   c , or the innermost layer, of the internal bladder  220 , and cyclic olefin copolymer is used as the material for the elastic modulus controlling layer  220   b , or the middle layer. As for the material for the gas barrier layer  220   a , or the outermost layer, EVOH (ethylene-vinyl acetate copolymer: EVA resin) is used. It is desired that functional adhesive resin is mixed in the elastic modulus controlling layer  220   b , because such a mixture eliminates the need for an adhesive layer between the adjacent functional layers, reducing the thickness of the wall of the internal bladder  220 . 
     As for the material for the external shell  210 , polypropylene is used, as it is used for the material for the innermost layer of the internal bladder  220 . Polypropylene is also used as the material for the first valve body  260   a.    
     The ID member  250  i,s provided with a plurality of ID member slots  252 , which are arranged at the left and right edges of the front surface, corresponding to the plurality of ID members  170  for the prevention of the incorrect installation of the ink container unit  200 . 
     The installation mistake preventing function is provided by the installation mistake prevention mechanism, which comprises the plurality of ID members  170  provided on the negative pressure controlling chamber unit  100  side, and the ID member slots  252  provided by the ID member  250  corresponding to the positions of the ID members  170 . Therefore, a large number of ink container unit installation areas can be made identifiable by changing the shapes and positions of the ID members  170  and ID member slots  252 . 
     The ID member slots  252  of the ID member  250 , and the joint opening  230  of the first valve body  260   a , are located in the front surface of the ink container unit  200 , that is, the front side in terms of the direction in which the ink container unit  200  is installed or removed. They are parts of the ID member  250  and first valve body  260   a , respectively. 
     The ink storing container  201  is formed by blow molding, and the ID member  250  and first valve body  260   a  are formed by injection molding. Giving the ink container unit  200  a three piece structure makes it possible to precisely form the valve body and ID member slots  252 . 
     If the ID member slots  252  are directly formed as the portions of the wall of the ink storing container  201  by blow molding, the shape of the internal space of the ink containing portion becomes complicated, affecting the separation of the internal bladder  100  wall, or the inner layer of the ink storing container  201 , which sometimes affects the negative pressure generated by the ink container unit  200 . Separately forming the ID member  250  and ink container portion  201 , and then attaching the ID member  250  to the ink containing portion  202 , as the ink container unit  200  in this embodiment is structured, eliminates the aforementioned effect, making it possible to generate and maintain stable-negative pressure in the ink storing container  201 . 
     The first valve body  260   a  is attached to at least the internal bladder  220  of the ink storing container  201 . More specifically, the first valve body  260   a  is attached by welding the exposed portion  221   a , that is, the ink outlet portion of the ink storing container  201 , to the surface of the joint opening  230  corresponding to the exposed portion  221   a . Since both the external shell  210  and the innermost layer of the internal bladder  220  are formed of the same material, that is, polypropylene, the first valve body  260   a  can be welded to the external shell  210  also at the periphery of the joint opening  230 . 
     The above described welding method increases accuracy in the positional relationship among the mutually welded components, while perfectly sealing the supply outlet portion of the ink storing container  201 , and therefore, preventing ink leakage or the like which tends to occur at the seal portion between the first valve body  260   a  and the ink storing container  201  when the ink container unit  200  is installed, removed, or the like motion. When the first valve body  260   a  is attached to the ink storing container  201  by welding as in the case of the ink container unit  200  in this embodiment, it is desired for the sake of better sealing that the material for the internal bladder  220  layer, which provides the bonding surface, is the same as the material for the first valve body  260   a.    
     As for the attachment of the ID member  250  to the external shell  210 , in order to firmly join them, the shell surface which faces the sealing surface  102  of the first valve body  260   a , which is bonded to the ink containing portion  210 , is joined, by interlocking, to the click portions  250   a  of the ID member  250 , which is located at the bottom portion of the ID member  250 , and the engagement portion  210   a  of the external shell  210 , which is located on the side walls of the external shell  210 , are interlocked with the other click portions  250   a  of the ID member  250 . 
     Regarding the word “interlocking”, the mutually interlockable portions of these components are structured in the form of a projection or an indentation which fit with each other in an easily disengageable manner. Interlocking the ID member  250  with the ink storing container  201  allows both components to move slightly against each other. Therefore, the force generated by the contact between the ID members  170  and the ID member slots  252  during the installation or removal of these components can be absorbed to prevent the ink container unit  200  and negative pressure controlling chamber unit  100  from being damaged during the installation or removal of these components. 
     Also, interlocking the ID member  250  with the ink storing container  201  using only a limited number of the portions of the possible contact area makes it easier to disassemble the ink container unit  200 , which is beneficial in consideration of its recycling. Providing indentations as the engagement portions  210   a  in the side walls of the external shell  210  makes the structure of the ink storing container  201  simpler to form by blow molding, and therefore, makes the mold pieces simpler. In addition, it makes it easier to control the film thickness. 
     Also regarding the joining of the ID member  250  to the external shell  210 , the ID member  250  is joined to the external shell  210  after the first valve body  260   a  is welded to the external shell  210 . Since the click portions  250   a  are interlocked with the engagement portions  210   a , in the state in which the peripheral portion of the first valve body  260   a  is tightly surrounded at the periphery of the joint opening  230  by the inward surface of the ID member  250 , the joint portion becomes stronger against the force which applies to the joint portion when the ink container unit  200  is installed or removed. 
     The shape of the ink storing container  201  is such that the portion to be covered by the ID member  250  is recessed, and the supply outlet portion protrudes. However, the protruding shape of the front side of the ink container unit  200  is hidden from view by the fixation of the ID member  250  to the ink storing container  201 . Further, the welding seam between the first valve body  260   a  and ink storing portion  201  is covered by the ID member  250 , being thereby protected. The relationship between the engagement portions  210   a  of the external shell  210  and the corresponding click portions  250   a  of the ID member  250 , with regard to which side is projecting and which side is recessed, may be reversal to their relationship in this embodiment. 
     As described before, it is assured by the joint pipe  180  and valve mechanism that ink does not leak when the ink container unit  200  is installed. In this embodiment, a rubber joint portion  280  is fitted around the base portion of the joint pipe  180  of the negative pressure controlling chamber unit  100  to deal with unpredictable ink leakage. The rubber joint portion  280  seals between the ID member  250  and ink container unit  200 , improving the degree of airtightness between the negative pressure controlling chamber unit  100  and ink container unit  200 . When removing the ink container unit  200 , this airtightness could function as resistance. However, in the case of this embodiment, the ID member  250  and ink storing container  201  are interlocked with the presence of a small amount of gap, allowing air to be introduced between the rubber joint portion  280  and ID member  250 , and therefore, although ink is prevented from leaking, the force necessary to be applied for removing the ink container unit  200  is not as large as it otherwise would be, because of the provision of the rubber joint portion  280 . 
     Further, the positions of the ink storing container  201  and IC member  250  can be controlled in terms of both the lengthwise and widthwise directions. The method for joining the ink storing container  201  with the ID member  250  does not need to be limited to a method such as the one described above; different joining points and different joining means may be employed. 
     Referring to FIGS. 2 and 22, the bottom wall of the ink storing container  201  is slanted upward toward the rear, and is engaged with the ink containing unit engagement portion  155  of the holder  150 , by the bottom rear portion, that is, the portion opposite to the ink outlet side. The holder  150  and ink container unit  200  are structured so that when removing the ink container unit  200  from the holder  150 , the portion of the ink storing container  201 , which is in contact with the ink containing portion engagement portion  155 , can be moved upward. In other words, when the ink container unit  200  is removed, the ink container unit  200  is rotated by a small angle. In this embodiment, the center of this rotation virtually coincides with the supply outlet opening (joint opening  230 ). However, strictly speaking, the position of this rotational center shifts as will be described later. In the case of the above described structural arrangement, which requires the ink container unit  200  to be rotationally moved to be disengaged from the holder  150 , the greater the difference by which the distance (A) from the rotational center of the ink container unit  200  to the bottom rear corner of the ink container unit  200  corresponding to the ink containing unit engagement portion  155 , is longer than the distance (B) from the same rotational center to the ink containing unit engagement portion  155 , the more frictionally do the bottom rear corner of the ink container unit  200  and the image containing unit engagement portion  155  rub against each other, requiring a substantially greater amount of force to install the ink container unit  200 , which sometimes causes problems such as deformation of the contact areas on both the ink container unit  200  side and holder  150  side. 
     Slanting the bottom wall of the ink storing container  201  so that the position of the ink containing portion engagement portion  155  side of the bottom wall of the ink storing container  201  becomes higher than that of the front end of the ink storing container  201 , as in this embodiment, prevents the ink container unit  200  from heavily rubbing against the holder  150  during its rotational motion. Therefore, the ink container unit  200  can be smoothly installed or removed. 
     In this embodiment, the joint opening  230  of the ink jet head cartridge is located in the bottom portion of the sidewall of the ink storing container  201 , on the negative pressure controlling chamber unit side, and the bottom portion of another wall of the ink storing container  201 , that is, the wall opposite to the wall in which the joint opening  230  is located is engaged with the ink container engagement portion  155 ; in other words, the bottom rear portion of the ink storing container  201  is engaged with the ink storing container engagement portion  155 . Also, the ink storing container engagement portion  155  extends upward from the bottom wall of the holder  150 , so that the position of the top portion of the ink storing container engagement portion  155  becomes approximately the same as the position  603  of the horizontal center line of the joint opening  230 , in terms of the vertical direction. With this arrangement, it is assured that the horizontal movement of the joint opening  230  is regulated by the ink storing container engagement portion  155  to keep the joint opening  230  correctly connected with the joint pipe  180 . In this embodiment, in order to assure that the joint opening  230  is correctly connected with the joint pipe  180  during the installation of the ink container unit  200 , the top end of the ink storing container engagement portion  155  is positioned at approximately the same height as the upper portion of the joint opening  230 , and the ink container unit  200  is removably installed into the holder  150  by rotating the ink container unit  200  about a portion of the front surface of the ink container unit  200  on the joint opening  230  side. During the removal of the ink container unit  200 , the portion of the ink container unit  200  which remains in contact with the negative pressure controlling chamber unit  100  functions as the rotational center for the ink container unit  200 . As is evident from the above description, making the bottom wall of the ink storing container  201  of the ink jet head cartridge slanted upward toward its bottom rear portion as described above reduces the difference between the distance from the rotational center  600  to the top end of the ink storing container engagement portion, and the distance from the rotational center  600  to the bottom end of the ink storing container engagement portion. Therefore, the portions of the ink container unit  200 , which make contact with the holder  150 , and the portions of the holder  150 , which make contact with the ink container unit  200 , are prevented from strongly rubbing against each other. Therefore, the ink container unit  200  can be smoothly installed or removed. 
     By shaping the ink storing container  201  and holder  150  as described above, it is possible to keep relatively small the size of the portion of the bottom rear portion of the ink storing container  201 , which rubs against the ink storing container engagement portion  155  during the installation or removal of the ink container unit  200 , and the size of the portion of the ink storing container engagement portion  155 , which rubs against the bottom rear portion of the ink storing container  201 , even if the joint opening  230  is enlarged to deliver ink at a greater volumetric rate. Therefore, the ink container unit  200  is prevented from uselessly rubbing against the ink storing container engagement portion  155  during the installation of the ink container unit  200  into the holder  150 , and yet, it is assured that the ink container unit  200  remains firmly attached to the holder  150 . 
     Next, referring to FIG. 22, the movement of the ink container unit  200  during its installation or removal will be described in detail. When the distance from the rotational center  600 , about which the ink container unit  200  rotates during its installation or removal, to the bottom end  602  of the ink container engagement portion, is greater than the distance from the same rotational center  600  to the top end  601  of the ink container engagement portion, by an excessive margin, the force necessary for the installation or removal of the ink container unit  200  is excessively large, and therefore, it sometimes occurs that the top end  601  of the ink container engagement portion is shaved, or the ink storing container  201  deforms. 
     Thus, the difference between the distance from the rotational center  600 , about which the ink container unit  200  rotates during its installation or removal, to the bottom end  602  of the ink container engagement portion, and the distance from the same rotational center  600  to the top end  601  of the ink container engagement portion, should be as small as possible within a range in which the ink container unit  200  is retained in the holder  150  with a proper degree of firmness while affording smooth installation or removal of the ink container unit  200 . 
     If the position of the rotational center  600  of the ink container unit  200  is made lower than the position of the center of the joint opening  230 , the distance from the rotational center  600 , about which the ink container unit  200  rotates during its installation or removal, to the top end  601  of the ink container engagement portion, becomes longer than the distance from the same rotational center  600  to the bottom end  602  of the ink container engagement portion. Therefore, it becomes difficult to accurately hold the ink storing container  201  at a point which is at the same height as the center of the joint opening  230 . Thus, in order to accurately position the vertical center of the joint portion  230 , it is desired that the position of the rotational center  600  of the ink container unit  200  is higher than the position of the vertical center of the joint opening  230 . 
     If the structure of the ink container unit  200  is changed so that the position of the rotational center  600  of ink container unit  200  becomes higher than the position  603  of the vertical center of the joint opening  230 , the portion of the ink container unit  200 , which corresponds to the ink container engagement portion  155 , becomes thicker, requiring the height of the ink storing container engagement portion  155  to be increased. As a result, there will be an increased possibility that the ink container unit  200  and holder  150  will be damaged. Thus, it is desired, in view of the smoothness of the installation or removal of the ink container unit  200 , that the position of the rotational center  600  of the ink container unit  200  is close to the vertical center of the joint opening  230 . The height of the ink container engagement portion  155  of the holder  150  has to be properly determined based only on the ease of the installation or removal of the ink container unit  200 . However, if the height of the ink container engagement portion  155  is increased so that the position of its top end becomes higher than that of the rotational center  600 , the length by which the ink container unit  200  contacts the ink container engagement portion  155  of the holder  150  becomes greater, which in turn increases the sizes of the portions on both sides, which rub against each other. Therefore, in consideration of the deterioration of the ink container unit  200  and holder  150 , the height of the ink container engagement portion  155  is such that the position of its top end is lower than that of the rotational center  600 . 
     In the ink jet head cartridge in this embodiment, the elastic force for keeping the position of the ink storing container  201  fixed in terms of the horizontal direction is a combination of the force generated by the resilient member  263  for pressing the valve plug  261 , and the force generated by the resiliency of the rubber joint portion  280  (FIG.  4 ). However, the configuration for generating the above resiliency does not need to be limited to the one in this embodiment; the bottom rear end, or the engagement portion, of the ink storing container  201 , the surface of the ink storing container engagement portion  155 , on the ink storing container side, the negative pressure controlling chamber unit  100 , or the like, may be provided with an elastic force generating means for keeping the position of the ink storing container  201  fixed in terms of the horizontal direction. When the ink storing container is in connection with the negative pressure controlling chamber, the rubber joint portion  280  remains compressed between the walls of the negative pressure controlling chamber and ink storing container, assuring that the joint portion (peripheral portion of the joint pipe) is airtightly sealed (it is not necessary to maintain perfect airtightness as long as the size of the area exposed to the outside air can be minimized). Also, the rubber joint portion  280  plays an auxiliary role in coordination with a sealing projection, which will be described later. 
     Next, the internal structure of the negative pressure controlling chamber unit  100  will be described. 
     In the negative pressure controlling chamber unit  100 , the absorbent material pieces  130  and  140  are disposed in layers as members for generating negative pressure, the former being on top of the latter. Thus, the absorbent material piece  130  is exposed to the outside air through the air vent  115 , whereas the absorbent material piece  140  is airtightly in contact with the absorbent material piece  130 , at its top surface, and also is airtightly in contact with the filter  161  at its bottom surface. The position of the interface between the absorbent material pieces  130  and  140  is such that when the ink jet head cartridge is placed in the same attitude as the ink jet head cartridge is in use, it is higher than the position of the uppermost portion of the joint pipe  180  as a liquid passage. 
     The absorbent material pieces  130  and  140  are formed of fibrous material, and are held in the negative pressure controlling chamber shell  110 , so that in the state in which the ink jet head cartridge  70  has been properly installed into the printer, its fibers extend in substantially the same, or primary, direction, being angled (preferably, in the virtually horizontal direction as they are in this embodiment) relative to the vertical direction. 
     As for the material for the absorbent material pieces  130  and  140 , the fibers of which are arranged in virtually the same direction, short (approximately 60 mm) crimped mixed strands of fiber formed of thermoplastic resin (polypropylene, polyethylene, and the like) are used. In production, a wad of such strands is put through a carding machine to parallel the strands, is heated (heating temperature is desired to be set higher than the melting point of polyethylene, which is relatively low, and lower than the molding point of polypropylene, which is relatively high), and then, is cut to a desired length. The fiber strands of the absorbent material pieces in this embodiment are greater in the degree of alignment in the surface portion than in the center portion, and therefore, the capillary force generated by the absorbent members is greater in the surface portion than in the center portion. However, the surfaces of the absorbent material pieces are not as flat as a mirror surface. In other words, they have a certain amount of unevenness which results mainly when the slivers are bundled; they are three dimensional, and the intersections of the slivers, at which they are welded to each other, are exposed from the surfaces of the absorbent material pieces. Thus, in strict terms, the interface  113   c  between the absorbent material pieces  130  and  140  is an interface between the two uneven surfaces, allowing ink to flow by a proper amount in the horizontal direction along the interface  113   c  and also through the adjacencies of the interface  113   c . In other words, it does not occur that ink is allowed to flow far more freely along the interface  113   c  than through its adjacencies, and therefore, an ink path is formed through the gaps between the walls of the negative pressure controlling chamber shell  110  and absorbent material pieces  130  and  140 , and along the interface  113   c . Thus, by making a structural arrangement so that the interface  113   c  between the absorbent material pieces  130  and  140  is above the uppermost portion of the joint pipe  180 , preferably, above and close to the uppermost portion of the joint pipe  180  as in this embodiment, when the ink jet head cartridge is positioned in the same attitude as it is when in use, the position of the interface between the ink and gas in the absorbent material pieces  130  and  140  during the gas-liquid exchange, which will be described later, can be made to coincide with the position of the interface  113   c . As a result, the negative pressure in the head portion during the ink supplying operation can be :stabilized. 
     Referring to FIG. 20, if attention is paid to the directionality of the strands of fiber in any portion of the fibrous absorbent material piece, it is evident that plural strands of fiber are extended in a direction F 1 , or the longitudinal direction of the absorbent material piece, in which the strands have been arranged by a carding machine. In terms of the direction F 2  perpendicular to the direction F 1 , the strands are connected to each other by being fused to each other at their intersections during the aforementioned heating process. Therefore, the fiber strands in the absorbent material pieces  130  and  140  are not likely to be separated from each other when the absorbent material pieces  130  or  140  is stretched in the direction F 1 . However, the fiber strands which are not likely to separate when pulled in the direction F 1  can be easily separated at the intersections at which they have been fused with each other if the absorbent material piece  130  or  140  is stretched in the direction F 2 . 
     Since the absorbent material pieces  130  and  140  formed of the fiber strands possess the above described directionality in terms of the strand arrangement, the primary fiber direction, that is, the fiber direction F 1  is different from the fiber  5 direction F 2  perpendicular to the direction F 1  in terms of how ink flows through the absorbent pieces, and also in terms of how ink is statically held therein. 
     To look at the internal structures of the absorbent material pieces  130  and  140  in more detail, the state of a wad of short strands of fiber crimped and carded as shown in FIG. 21, ( a ), changes to the state shown in FIG. 21, ( b ), as it is heated. More specifically, in a region α in which plural short strands of crimped fiber extend in an overlapping manner, more or less in the same direction, the fiber strands are likely to be fused to each other at their intersections, becoming connected as shown in FIG. 21, ( b ) and therefore, difficult to separate in the direction F 1  in FIG.  20 . On the other hand, the  21  tips of the short strands of crimped fiber (tips β and γ in FIG. 21, ( a )) are likely to three-dimensionally fuse with other strands like the tip  1  in FIG. 21, ( b ), or remain unattached like the tip γ in FIG. 21, ( b ). However, all the strands do extend in the same direction. In other words, some strands extend in the nonconforming direction and intersect with the adjacent strands (region ε in FIG. 21, ( a )) even before heat is applied, and as heat is applied, they fuse with the adjacent strands in the position they are in, (region ε in FIG. 21, ( b )). Thus, compared to a conventional absorbent piece constituted of a bundle of unidirectionally arranged strands of fiber, the absorbent members in this embodiment are also far more difficult to split in the direction F 2 . 
     Further, in this embodiment, the absorbent pieces  130  and  140  are disposed so that the primary fiber strand direction F 1  in the absorbent pieces  130  and  140  becomes nearly parallel to the horizontal direction and the line which connects the joint portion and the ink supply outlet. Therefore, after the connection of ink storing container  201 , the gas-liquid interface L (interface between ink and gas) in the absorbent piece  140  becomes nearly horizontal, that is, virtually parallel to the primary fiber strand direction F 1 , remaining virtually horizontal even if ambient changes occur, and as the ambience settles, the gas-liquid interface L returns to its original position. Thus, the position of the gas-liquid interface in terms of the gravitational direction is not affected by the number of the cycles of the ambient change. 
     Thus, even when the ink container unit  200  is replaced with a fresh one because the ink storing container  201  has run out of ink, the gas-liquid interface remains virtually horizontal, and therefore, the size of the buffering space  116  does not decrease no matter how many times the ink container unit  200  is replaced. 
     All that is necessary in order to keep the position of the gas-liquid interface stable in spite of the ambient changes during the gas-liquid exchange is that the fiber strands in the region immediately above the joint between the negative pressure controlling chamber unit  100  and ink container unit  200  (in the case of this embodiment, above the position of the joint pipe  180 ), preferably inclusive of the adjacencies of the region immediately above the joint, are extended in the more or less horizontal direction. From a different viewpoint, all that is necessary is that the above described region is between the ink delivery interface and the joint between the negative pressure controlling chamber unit  100  and ink container unit  200 . From another viewpoint, all that is necessary is that the position of this region is above the gas-liquid interface while gas-liquid exchange is occurring. To analyze the latter viewpoint with reference to the functionality of this region in which the fiber strands posses the above described directionality, this region contributes to keeping horizontal the gas-liquid interface in the absorbent piece  140  while the liquid is supplied through the gas-liquid exchange; in other words, the region contributes to regulate the changes which occur in the vertical direction in the absorbent material piece  140  in response to the movement of the liquid into the absorbent material piece  140  from the ink storing container  201 . 
     The provision of the above described region or layer in the absorbent material piece  140  makes it possible to reduce the unevenness of the gas-liquid interface L in terms of the gravity direction. Further, it is desired that the fiber strands in the aforementioned region or layer be arranged so that they appear to extend in parallel in the aforementioned primary direction even when they are seen from the direction perpendicular to the horizontal direction of the absorbent material piece  140 , because such an arrangement enhances the effect of the directional arrangement of the fiber strands in the more or less parallel manner in the primary direction. 
     Regarding the direction in which the fiber strands are extended, theoretically, when the general direction in which the fiber strands are extended is angled relative to the vertical direction, the above described effect can be provided, although the amount of effect may be small if the angle is small. In practical terms, as long as the above described angle was in a range of ±30° relative to the horizontal direction, the effect was clearly confirmed. Thus, the term “more or less” in the phrase “more or less horizontal” in this specification includes the above range. 
     In this embodiment, the fiber strands in the absorbent material piece  140  are extended more or less in parallel in the primary direction also in the region below and adjacent to the joint portion, preventing therefore the gas-liquid interface L from becoming unpredictably uneven in the region below the uppermost portion of the joint portion, as shown in FIG. 6, during the gas-liquid exchange. Therefore, it does not occur that the ink jet head cartridge fails to be supplied with a proper amount of ink due to the interruption of ink delivery. 
     More specifically, during the gas-liquid exchange, the outside air introduced through the air vent  115  reaches the gas-liquid interface L. As it reaches the interface L, it is dispersed along the fiber strands. As a result, the interface L is kept more or less horizontal during the gas-liquid exchange; it remains stable, assuring that the ink is supplied while a stable amount of negative pressure is maintained. Since the primary direction in which the fiber strands are extended in this embodiment is more or less horizontal, the ink is consumed through the gas-liquid exchange in such a manner that the top surface of the ink remains more or less horizontal, making it possible to provide an ink supplying system which minimizes the amount of the ink left unused, even the amount of the ink left unused in the negative pressure controlling chamber shell  110 . Therefore, in the case of an ink supplying system such as the system in this embodiment which allows the ink containing unit  200 , in which liquid is directly stored, to be replaced, it is easier to provide the absorbent material pieces  130  and  140  with regions in which ink is not retained. In other words, it is easier to increase the buffering space ratio, to provide an ink supplying system which is substantially more resistant to the ambient changes than a conventional ink supplying system. 
     When the ink jet head cartridge in this embodiment is the type of cartridge mountable in a serial type printer, it is mounted on a carriage which is shuttled. As this carriage is shuttled, the ink in the ink jet head cartridge is subjected to the force generated by the movement of the carriage, more specifically, the component of the force in the direction of the carriage movement. In order to minimize the adverse effects of this force upon the ink delivery from the ink container unit  200  to ink jet head unit  160 , the direction of the fiber strands in the absorbent material pieces  130  and  140  and the direction in which the ink container unit  200  and negative pressure controlling chamber unit  100  are connected, are desired to coincide with the direction of the line which connects:the joint opening  230  of the ink container unit  200  and the ink outlet  131  of the negative pressure controlling chamber shell  110 . 
     &lt;Operation for Installing Ink Containing Unit&gt; 
     Next, referring to FIG. 4, the operation for installing the ink containing unit  200  into the integral combination of the negative pressure controlling chamber unit  100  and holder  150  will be described. 
     FIG. 4 is a sectional drawing for depicting the operation for installing the ink container unit  200  into the holder  150  to which the negative pressure controlling chamber unit  100  has been attached. The ink container unit  200  is installed into the holder  150  by being moved in the direction F as well as the direction G, while being slightly rotated by being guided by the unillustrated lateral guides, the bottom wall of the holder  150 , the guiding portions  121  with which the negative pressure controlling chamber cover  120  of the negative pressure controlling chamber unit  100 , the ink container engagement portion  155 , that is, the rear end portion of the holder  150 . 
     More specifically, the installation of the ink container unit  200  occurs as follows. First, the ink container unit  200  is moved to a point indicated in FIG. 4, ( a ), that is, the point at which the slanted surface  251  of the ink container unit  200  comes into contact with the ID members  170  with which the negative pressure controlling chamber unit  100  is provided to prevent the wrong installation of the ink container unit  200 . The holder  150  and ink container unit  200  are structured so that at the point in time when the above described contact occurs, the joint pipe  180  has yet to enter the joint opening  230 . If a wrong ink container unit  200  is inserted, the slanted surface  251  of the wrong ink container unit  200  collides with the ID members  170  at this point in time, preventing the wrong ink container unit  200  from being inserted further. With this structural arrangement of the ink jet head cartridge  70 , the joint opening  230  of the wrong ink container unit  200  does not make contact with joint pipe  180 . Therefore, the problems which occur at the joint portion as a wrong ink container unit  200  is inserted, for example, the mixture of inks with different color, and the solidification of ink in the absorbent material pieces  130  and  140  (anions in one type of ink react with cations in another type of ink), which might cause the negative pressure controlling chamber unit  100  to stop functioning, can be prevented, and therefore, it will never occurs that the head and ink containing portion of an apparatus, the ink containing portions of which are replaceable, needs to be replaced due to the occurrence of such problems. Further, since the ID portions of the ID member  250  are provided on the slanted surface of the ID member, the plurality of ID members  170  can be almost simultaneously fitted into the correspondent ID slots to confirm that a correct ink container unit  200  is being inserted; a reliable installation mistake prevention mechanism is provided. 
     In the next step, the ink container unit  200  is moved toward the negative pressure controlling chamber unit  100  so that the ID members  170  and joint pipe  180  are inserted into the ID member slots  252  and joint opening  230 , respectively, at the same time, as shown in FIG. 4, ( b ), until the leading end of the ink container unit  200  reaches the negative pressure controlling chamber unit  100  as shown in FIG. 4, ( c ). Next, the ink container unit  200  is rotationally moved in the direction indicated by an arrow mark G. 
     During the rotational movement of the ink container unit  200 , the tip of the joint pipe  180  comes into contact with the valve plug  261  and pushes it. At a result, the valve mechanism opens, allowing the internal space of the ink container unit  200  to be connected to the internal space of the negative pressure controlling chamber unit  100 , in other words, enabling the ink  300  in the ink container unit  200  to be supplied into the negative pressure controlling chamber unit  100 . The detailed description of the opening or closing movement of this valve mechanism will be given later. 
     Next, the ink container unit  200  is further rotated in the direction of the arrow mark G, until the ink container unit  200  settles as shown in FIG.  2 . As a result, the bottom rear end portion of the ink container unit  200  becomes engaged with the ink container engagement portion  155  of the holder  150 ; in other words, the ink container unit  200  is correctly placed in the predetermined space for the ink container unit  200 . During this second rotational movement of the ink container unit  200 , the ID members  170  slightly come out of the ID member slots  252 . The rearward force for correctly retaining the ink container unit  200  in the ink container unit space is generated toward the ink container engagement portion  155  of the holder  150  by the resilient member  263  in the ink container unit  200  and the rubber joint portion  280  fitted around the joint pipe  180 . 
     Since the ID member slots  252  are provided in the slanted front wall of the ink container unit  200  which is rotationally installed or removed, and also, the bottom wall of the ink container unit  200  is slanted, it is possible to minimize the space necessary to assure that the ink container unit  200  is installed or removed without making mistakes or mixing inks of different color. 
     As soon as the ink container unit  200  is connected with the negative pressure controlling chamber unit  100  as described above, the ink moves until the internal pressure of the negative pressure controlling chamber unit  100  and the internal pressure of the ink storing container  201  equalize to realize the equilibrium state illustrated in FIG. 4, ( d ), in which the internal pressure of the joint pipe  180  and joint opening  230  remains negative (this state is called “initial state of usage”). 
     At this time, the ink movement which results in the aforementioned equilibrium will be described in detail. 
     The valve mechanism provided in the joint opening  230  of the ink storing container  201  is opened by the installation of the ink container unit  200 . Even after the opening of the valve mechanism, the ink holding portion of the ink storing container  201  remains virtually sealed except for the small passage through the joint pipe  230 . As a result, the ink in the ink storing container  201  flows into the joint opening  230 , forming an ink path between the internal space of the ink storing container  201  and the absorbent material piece  140  in the negative pressure controlling chamber unit  100 . As the ink path is formed, the ink begins to move from the ink storing container  201  into the absorbent material piece  140  because of the capillary force of the absorbent material piece  140 . As a result, the ink gas interface in the absorbent material piece  140  rises. Meanwhile, the internal bladder  220  begins to deform, starting from the center portion of the largest wall, in the direction to reduce the internal volume. 
     The external shell  210  functions to impede the displacement of the corner portions of the internal bladder  220 , countering the deformation of the internal bladder  220  caused by the ink consumption. In other words, it works to preserve the pre-installation state of the internal bladder  220  (initial state illustrated in FIGS. 4, ( a )-( c )). Therefore, the internal bladder  220  produces and maintains a proper amount of negative pressure correspondent to the amount of deformation, without suddenly deforming. 
     Since the space between the external shell  210  and internal bladder  220  is connected to the outside through the air vent  222 , air is introduced into the space between the external shell  210  and internal bladder  220  in response to the aforementioned deformation. 
     Even if air is present in the joint opening  230  and joint pipe  180 , this air easily moves into the internal bladder  220  because the internal bladder  220  deforms as the ink in the internal bladder  220  is drawn out through the ink path formed as the ink from the ink storing container  201  comes into contact with the absorbent material piece  140 . 
     The ink movement continues until the amount of the static negative pressure in the joint opening  230  of the ink storing container  201  becomes the same as the amount of the static negative pressure in the joint pipe  180  of the negative pressure controlling chamber unit  100 . 
     As described above, the ink movement from the ink storing container  201  into the negative pressure controlling chamber unit  100 , which is triggered by the connection of the ink storing container  201  with the negative pressure controlling chamber unit  100 , continues without the introduction of gas into the ink storing container  201  through the absorbent material pieces  130  and  140 . What is important to this process is to configure the ink storing container  201  and negative pressure controlling chamber unit  100  according to the type of a liquid jet recording means to which the ink container unit  200  is connected, so that the static negative pressures in the ink storing container  201  and negative pressure controlling chamber unit  100  reach proper values for preventing ink from leaking from the liquid jet recording means such as the ink jet head unit  160  which is connected to the ink outlet of the negative pressure controlling chamber unit  100 . 
     The amount of the ink held in the absorbent material piece  130  prior to the connection varies. Therefore, some regions in the absorbent piece  140  remain unfilled with ink. These regions can be used as the buffering regions. 
     On the other hand, sometimes the internal pressures of the joint pipe  180  and joint opening  230  are caused to become positive due to the aforementioned variation. When there is such a possibility, a small amount of ink may be flowed out by performing a recovery operation with a suction-based recovering means, with which the main assembly of a liquid jet recording apparatus is provided, to deal with the possibility. This recovery means will be described later. 
     As described before, the ink container unit  200  in this embodiment is installed into the holder  150  through a movement which involves a slight rotation; it is inserted at an angle while resting on the ink container engagement portion  155  of the holder  150 , by its bottom wall, and after the bottom rear end of the ink container unit  200  goes over the ink container engagement portion  155 , it is pushed downward into the holder  150 . When the ink container unit  200  is removed from the holder  150 , the above described steps are reversely taken. The valve mechanism with which the ink container unit  200  is provided is opened or closed as the ink container unit  200  is installed or removed, respectively. 
     &lt;Opening or Closing of Valve Mechanism&gt; 
     Hereinafter, referring to FIGS. 5, ( a )-( e ), the operation for opening or closing the valve mechanism will be described. FIG. 5, ( a ), shows the states of the joint pipe  180  and its adjacencies, and the joint opening  230  and its adjacencies, immediately before the joint pipe  180  is inserted into the joint opening  230 , but after the ink container unit  200  was inserted into the holder  150  at an angle so that the joint opening  230  tilts slightly downward. 
     The joint pipe  180  is provided with a sealing projection  180   a , which is integrally formed with the joint pipe  180 , and extends on the peripheral surface of the joint pipe  180 , encircling the peripheral surface of the joint pipe  180 . It is also provided with a valve activation projection  180   b , which forms the tip of the joint pipe  180 . The sealing projection  180   a  comes into contact with the joint sealing surface  260  of the joint opening  230  as the joint pipe  180  is inserted into the joint opening  230 . The sealing projection  180   a  extends around the joint pipe  180  at an angle so that the distance from the uppermost portion of the sealing projection  180   a  to the joint sealing surface  260  becomes greater than the distance from the bottommost portion of the sealing projection  180   a  to the joint sealing surface  260 . 
     When the ink container unit  200  is installed or removed, the joint sealing surface rubs against the sealing projection  180   a , as will be described later. Therefore, the material for the sealing projection  180   a  is desired to be such material that is slippery and yet capable of sealing between itself and an object it contacts. The configuration of the resilient member  263  for keeping the valve plug  26   a  pressed upon or toward the first valve body  260   a  does not need to be limited to a particular one; a springy member such as a coil spring or a plate spring, or a resilient member formed of rubber or the like, may be employed. However, in consideration of recycling, a resilient member formed of resin is preferable. 
     In the state depicted in FIG. 5, ( a ), the valve activation projection  180   b  is yet to make contact with the valve plug  261 , and the seal portion of the valve plug  261 , provided at the periphery of the joint pipe  180 , on the joint pipe side, is in contact with the seal portion of the first valve body  260   a , with the valve plug  261  being under the pressure from the resilient member  263 . Therefore, the ink container unit  200  remains airtightly sealed. 
     As the ink container unit  200  is inserted further into the holder  150 , the joint portion is sealed at the sealing surface  260  of the joint opening  230  by the sealing projection  180   a . During this sealing process, first, the bottom side of the sealing projection  180   a  comes into contact with the joint sealing surface  260 , gradually increasing the size of the contact area toward the top side of the sealing projection  180   a  while sliding against the joint sealing surface  260 . Eventually, the top side of the sealing projecting  180   a  comes into contact with the joint sealing surface  260  as shown in FIG. 5, ( c ). As a result, the sealing projection  180   a  makes contact with the joint sealing surface  260 , by the entire peripheral surface, sealing the joint opening  230 . 
     In the state illustrated in FIG. 5, ( c ), the valve activation projection  180   b  is not in contact with the valve plug  261 , and therefore, the valve mechanism is not open. In other words, before the valve mechanism is opened, the gap between the joint pipe  180  and joint opening  230  is sealed, preventing ink from leaking from the joint opening  230  during the installation of the ink container unit  200 . 
     Further, as described above, the joint opening  230  is gradually sealed from the bottom side of the joint sealing surface  260 . Therefore, until the joint opening  230  is sealed by the sealing projection  180   a , the air in the joint opening  230  is discharged through the gap between the sealing projection  180   a  and joint sealing surface  260 . As the air in the joint opening  230  is discharged as described above, the amount of the air remaining in the joint opening  230  after the joint opening  230  is sealed is minimized, preventing the air in the joint opening  230  from being excessively compressed by the invasion of the joint pipe  180  into the joint opening  230 , in other words, preventing the internal pressure of the joint opening  230  from rising excessively. Thus, it is possible to prevent the phenomenon that before the ink container unit  200  is completely installed into the holder  150 , the valve mechanism is inadvertently opened by the increased internal pressure of the joint opening  230 , and ink leaks into the joint opening  230 . 
     As the ink container unit  200  is further inserted, the valve activation projection  180   b  pushes the valve plug  261  against the resiliency of the resilient member  263 , with the joint opening  230  remaining sealed by the sealing projection  180   a , as shown in FIG. 5, ( d ). As a result, the internal space of the ink storing container  201  becomes connected to the internal space of the joint opening  230  through the opening  260   c  of the second valve body  26 . Consequently, the air in the joint opening  230  is allowed to be drawn into the ink container unit  200  through the opening  260   c , and the ink in the ink container unit  200  is supplied into the negative pressure controlling chamber shell  110  (FIG.  2 ). 
     As the air in the joint opening  230  is drawn into the ink container unit. 200  as described above, the negative pressure in the internal bladder  220  (FIG. 2) is reduced, for example, when an ink container unit  200  the ink in which has been partially consumed is re-installed. Therefore, the balance in the internal negative pressure between the negative pressure controlling chamber shell  110  and internal bladder  220  is improved, preventing the ink from being inefficiently supplied into the negative pressure controlling chamber shell  110  after the re-installation of the ink container unit  200 . 
     After the completion of the above described steps, the ink container unit  200  is pushed down onto the bottom wall of the holder  150  to finish installing the ink container unit  200  into the holder  150  as shown in FIG. 5, ( e ). As a result, the joint opening  230  is perfectly connected to the joint pipe  180 , realizing the aforementioned state which assures that gas-liquid exchange occurs flawlessly. 
     In this embodiment, the opening  260   c  of the second valve body  260   b  is located adjacent to the valve body seal portion  264  and on the bottom side of the ink container unit  200 . According to the configuration of this opening  260 , during the opening of the valve mechanism, more specifically, immediately after the valve plug  261  is moved toward the valve cover  262  by being pushed by the valve activation projection  180   b , the ink in the ink container unit  200  begins to be supplied into the negative pressure controlling chamber unit  100 . Also, it is possible to minimize the amount of the ink which remains in the ink container unit  200  when the ink container unit  200  needs to be discarded because the ink therein can no longer be drawn out. 
     Also in this embodiment, elastomer is used as the material for the joint sealing surface  260 , that is, the seal portion, of the first valve body  260   a . With the use of elastomer as the material for the joint sealing surface  260 , it is assured that because of the resilience of the elastomer, the joint between the joint sealing surface  260  and the sealing projection  180   a  of the joint pipe  180  is perfectly sealed, and also, the joint between the seal portion of the first valve body  260   a  and the correspondent seal portion of the valve plug  261  is perfectly sealed. In addition, by providing the elastomer with an amount of resiliency exceeding the minimum amount of resiliency necessary to assure that the joint between the first valve body  260   a  and joint pipe  180  is perfectly sealed (for example, by increasing the thickness of the elastomer layer), the flexibility of elastomer compensates for the effects of the misalignment, twisting, and/or rubbing, which occur at the contact point between the joint pipe  180  and valve plug  261  during the serial scanning movement of an ink jet head cartridge; it is doubly assured that the joint remains perfectly sealed. The joint sealing surface  260 , the material for which is elastomer, can be integrally formed with the first valve body  260   a , making it possible to provide the above described effects without increasing the number of components. Elastomer usage does not need to be limited to the above described structure; elastomer may also be used as the material for the sealing projection  180   a  of the joint pipe  180 , the seal portion of the valve plug  261 , and the like. 
     On the other hand, when the ink container unit  200  is removed from the holder  150 , the above described installation steps occur in reverse, unsealing the joint opening.  230 , and allowing the valve mechanism to close. 
     In other words, as the ink container unit  200  is pulled in the direction to remove it from the holder  150 , while gradually rotating the ink container unit  200  in the direction opposite to the installation direction, first, the valve plug  261  moves forward due to the resiliency of the resilient member  263 , and presses on the seal portion of the first valve body  260   a  by its sealing surface to close the joint opening  230 . 
     Then, as the ink container unit  200  is pulled out of the holder  150 , the gap between the wall of the joint opening  230  and the joint pipe  180 , which remained sealed by the sealing projection  180   a , is unsealed. Since this gap is unsealed after the closing of the valve mechanism, it does not occur that ink is wastefully released into the joint opening  230 . 
     In addition, since the sealing projection  180   a  is disposed at an angle as described before, the unsealing of the joint opening  230  occurs from the top side of the sealing projection  180   a . Before the joint opening  230  is unsealed, ink remains in the joint opening  230  and joint pipe  180 . However, it is at the top side where the unsealing starts. In other words, the bottom side remains sealed, preventing ink from leaking out of the joint opening  230 . Further, the internal pressure of the joint opening  230  and joint pipe  180  is negative, and therefore, as the joint is unsealed from the top side of the sealing projection  180   a , the outside air enters into the joint opening  230 , causing the ink remaining in the joint opening  230  and  180  to be drawn into the negative pressure controlling chamber shell  110 . 
     By causing the joint opening  230  to be unsealed starting from the top side of the sealing projection  180   a  to make the ink remaining in the joint opening  230  move into the negative pressure controlling chamber shell  110 , it is possible to prevent ink from leaking from the joint opening  230  as the ink container unit  200  is removed from the holder  150 . 
     As described above, according to the structure of the junction between the ink container unit  200  and negative pressure controlling chamber shell  110 , the joint opening  230  is sealed before the valve mechanism of the ink container unit  200  is activated, and therefore, ink is prevented from inadvertently leaking from the joint opening  230 . Further, since a time lag is provided between the top and bottom sides of the sealing projection  180   a  in terms of the sealing and unsealing timing, the valve plug  261  is prevented from inadvertently moving during the connection, and the ink remaining in the joint opening  230  is prevented from leaking during the connection and during the removal. 
     Also in this embodiment, the valve plug  261  is disposed in the joint opening  230 , at a point deeper inside the joint opening  230 , away from the outside opening of the joint opening  230 , and the movement of the valve plug  261  is controlled by the valve activation projection  180   b  provided at the projecting end of the joint pipe  180 . Therefore, a user is not required to touch the valve plug  261 , being prevented from being contaminated by the ink adhering to the valve plug  261 . 
     &lt;Relationship between Engagement or Disengagement of Joint Portion, and ID&gt; 
     Next, referring to FIGS. 4 and 5, the relationship between the engagement or disengagement of the joint portion, and ID will be described. FIGS. 4 and 5 are drawings for depicting the steps for installing the ink container unit  200  into the holder  150 , wherein FIGS. 4, ( a ), ( b ), and ( c ), and FIGS. 5, ( a ), ( b ), and ( c ), correspondingly represent the same steps. FIGS. 4 and 5 show in detail the portion related to ID, and the joint portion, respectively. 
     In the first step, the ink container unit  200  is inserted up to the position illustrated in FIG. 4, ( a ) and FIG. 5, ( a ), at which the plurality of ID members  170  for preventing the ink container unit installation error make contact with the slanted wall  251  of the ink container. The holder  150  and ink container unit  200  are structured so that at this point in time, the joint opening  230  and joint pipe  180  do not make contact. If a wrong ink container unit  200  is inserted, the slanted surface  251  of the wrong ink container unit  200  collides with the ID members  170  at this point in time, preventing the wrong ink container unit  200  from being inserted further. With this structural arrangement, the joint opening  230  of the wrong ink container unit  200  never makes contact with joint pipe  180 . Therefore, the problems which occur at the joint portion as a wrong ink container unit  200  is inserted, for example, the mixture of inks with different color, ink solidification, production of incomplete images, and breaking down of the apparatus, can be prevented, and therefore, it never occurs that the head and ink containing portion of an apparatus, the ink containing portions of which are replaceable, will be replaced due to the occurrence of such problems. 
     If the inserted ink container unit  200  is a correct one, the positions of the ID members  170  match the positions of the ID member slots  252 . Therefore, the ink-container unit  200  is inserted a little deeper toward the negative pressure controlling chamber unit  100  to a position shown in FIG. 4, ( b ). At this position, the joint sealing&#39;surface  260  of the joint opening  230  of the ink container unit  200  has come into contact with the bottom side of the sealing projection  180   a  of the joint pipe  180 . 
     Thereafter, the both sides are completely joined through the steps described before, providing a passage between the internal space of the ink container unit  200  and the internal space of the negative pressure controlling chamber unit  100 . 
     In the above described embodiment, the sealing projection  180   a  is an integral part of the joint pipe  180 . However, the two components may be separately formed. In such a case, the sealing projection  180   a  is fitted around the joint pipe  180 , being loosely held by a projection formed on the peripheral surface of the joint pipe  180 , or a groove provided in the peripheral surface of the joint pipe  180 , so that the sealing projection  180   a  is allowed to move on the peripheral surface of the joint pipe  180 . However, the joint portion is structured so that within the moving range of the independent sealing projection  180   a , the valve action controlling projection  180   b  does not make contact with the valve plug  261  until the sealing projection  180   a  comes into contact with the joint sealing surface  260 . 
     In the above description of this embodiment, it is described that as the ink container unit  200  is further inserted, the bottom side of the sealing projection  180   a  comes into contact with the joint sealing surface  260 , and the sealing projection  180   a  slides on the joint sealing surface  260 , gradually expanding the contact range between the sealing projection  180   a  and the joint sealing surface  260 , upward toward the top side of the sealing projection  180   a , until the top end of the sealing projection  180   a  finally comes into contact with the joint sealing surface  260 . However, the installation process may be such that, first, the top side of the sealing projection  180   a  comes into contact with the joint sealing surface  260 , and as the ink container unit  200  is further inserted, the sealing projection  180   a  slides on the joint sealing surface  260 , gradually expanding the contact range between the sealing projection  180   a  and the joint sealing surface  260 , downward toward the bottom end of the sealing projection  180   a , until the bottom end of the sealing projection  180   a  finally makes contact with the joint sealing surface  260   a . Further, the contact between the sealing projection  180   a  and joint sealing surface  260  may occur simultaneously at both the top and bottom sides. During the above process, if the air present between the joint pipe  180  and valve plug  261  opens the valve mechanism by pushing the valve plug  261  inward of the joint opening  230 , the ink  300  within the ink storing container  201  does not leak outward, because the joint opening  230  has been completely sealed at the joint between the sealing projection  180   a  and joint sealing surface  260 . In other words, the essential point of this invention is that the valve mechanism is opened only after the joint between the joint pipe  180  and joint opening  230  is completely sealed. According to this structure, it does not occur that the ink  300  within the ink container unit  200  leaks out during the installation of the ink container unit  200 . In addition, the air pushed into the joint opening  230  enters the ink container unit  200 , and pushes out the ink  300  in the ink storing container  201  into the joint opening  230 , contributing to smoothly supplying ink from the ink storing container  201  into the absorbent material piece  140 . 
     &lt;Ink Supplying Operation&gt; 
     Next, referring to FIG. 6, the ink supplying operation of the ink jet head cartridge illustrated in FIG. 2 will be described. FIG. 6 is a sectional drawing for describing the ink supplying operation of the ink jet head cartridge illustrated in FIG.  2 . 
     By dividing the absorbent material in the negative pressure controlling chamber unit  100  into a plurality of pieces, and positioning the interface between the divided pieces of the absorbent material so that the interface will,be positioned above the top end of the joint pipe  180  when the ink jet head cartridge is disposed in the attitude in which it is used, as described above, it becomes possible to consume the ink within the absorbent piece  140 , or the bottom piece, after the ink within the absorbent material piece  130 , or the top piece, if ink is present in both the absorbent material pieces  130  and  140  of the ink jet head cartridge illustrated in FIG.  2 . Further, if the position of the gas-liquid interface L changes due to the ambient changes, ink seeps into the absorbent material piece  130  after filling up, first, the absorbent material piece  140  and the adjacencies of the interface  113   c  between the absorbent material pieces  130  and  140 . Therefore, it is assured that buffering zone in addition to the buffering space  116  is provided in the negative pressure controlling chamber unit  100 . Making the strength of the capillary force of the absorbent material piece  140  higher compared to that of the absorbent material piece  130  assures that the ink in the absorbent material piece  130  is consumed when the ink jet head cartridge is operating. 
     Further, in this embodiment, the absorbent material piece  130  remains pressed toward the absorbent material piece  140  by the ribs of the negative pressure controlling chamber cover  120 , and therefore, the absorbent material piece  130  is kept in contact with the absorbent material piece  140 , forming the interface  113   c . The compression ratios of the absorbent material pieces  130  and  140  are higher adjacent to the interface  113   c  than those in the other portions, and therefore, the capillary force is greater adjacent to the interface  113   c  than that in the other portions. More specifically, representing the capillary force of the absorbent material piece  140 , the capillary force of the absorbent material piece  130 , and the capillary force of the area adjacent to the interface  113   c  between the absorbent material pieces  130  and  140 , with P 1 , P 2 , and PS, correspondingly, their relationship is: P 2 &lt;P 1  &lt;PS. Providing the area adjacent to the interface  113   c  between the absorbent material pieces  130  and  140  with such capillary force that is stronger than that in the other areas assures that the strength of the capillary force in the area adjacent to the interface  113   c  exceeds the strength necessary to meet the above described requirement, even if the ranges of the strengths of the P 1  and P 2  overlap with each other because of the unevenness of the absorbent material pieces  130  and  140  in terms of their density, or compression. Therefore, it is assured that the above described effects will be provided. Further, positioning the joint pipe  180  below, and adjacent to, the interface  113   c  between the absorbent material pieces  130  and  140  assures that the gas-liquid interface remains at this position, and therefore, is desired. 
     Accordingly, next, the method for forming the interface  113   c , in this embodiment, will be described. In this embodiment, olefinic fiber (2 denier) with a capillary force of −110 mmAq (P 1 =−110 mmAq) is used as the material for the absorbent material piece  140  as a capillary force generating member. The hardness of the absorbent material pieces  130  and  140  is 0.69 kgf/mm. The method for measuring their hardness is such that, first, the resilient force generated as a pushing rod with a diameter of 15 mm is pushed against the absorbent material placed in the negative pressure controlling chamber shell  110  is measured, and then, the hardness is obtained from the relationship between the distance the pushing rod was inserted, and the measured amount of the resilient force correspondent to the distance. On the other hand, the same material as that for the absorbent material piece  140 , that is, olefinic fiber, is used as the material for the absorbent material piece  130 . However, compared to the absorbent material piece  140 , the absorbent material piece  130  is made weaker in capillary force (P 2 =−80 mmAq), and is made larger in the fiber diameter (6 denier), making it higher in rigidity at 1.88 kgf/mm. 
     By making the absorbent material piece  130 , which is weaker in capillary force than the absorbent material piece  140 , greater in hardness than the absorbent material piece  140 , placing them in combination, and in contact, with each other, and keeping them pressed against each other, causes the absorbent material piece  140  to be kept more compressed than the absorbent material piece  130 , adjacent to the interface  113   c  between the absorbent material pieces  130  and  140 . Therefore, the aforementioned relationship in capillary force (P 2 &lt;P 1 &lt;PS) is established adjacent to the interface  113   c , and also it is assured that the difference between the P 2  and PS remains always greater than the difference between the P 2  and P 1 . 
     &lt;Ink Consumption&gt; 
     Next, referring to FIGS. 6-8, the outlines of the ink consuming process will be described from the time when the ink container unit  200  has been installed into the holder  150  and has become connected to the negative pressure controlling chamber unit  100 , to the time when the ink in the ink storing container  201  begins to be consumed. FIG. 7 is a drawing for describing the state of the ink during the ink consumption described with reference to FIG. 6, and FIG. 8 is a graph for depicting the effects of the deformation of the internal bladder  220  upon the prevention of the internal pressure change in the ink container unit  200 . 
     First, as the ink storing container  201  is connected to the negative pressure controlling chamber unit  100 , the ink in the ink storing container  201  moves into the negative pressure controlling chamber unit  100  until the internal,pressure of the negative pressure controlling chamber unit  100  becomes equal to the internal pressure of the ink storing container  201 , readying the ink jet head cartridge for a recording operation. Next, as the ink begins to be consumed by the ink jet head unit  160 , both the ink in the internal bladder  220  and the ink in the absorbent material piece  140  are consumed, maintaining such a balance that the value of the static negative pressure generated by the internal bladder  220  and absorbent material piece  140  increases (first state: range A in FIG. 7, ( a )). In this state, when ink is in the absorbent material piece  130 , the ink in the absorbent material piece  130  is also consumed. FIG. 7, ( a ) is a graph for describing one of the examples of the rate at which the negative pressure in the ink delivery tube  165  varies. In FIG. 7, ( a ), the axis of abscissa represents the rate at which the ink is drawn out of the negative pressure controlling chamber shell  110  through the ink delivery tube  160 , and the axis of ordinates represents the value of the negative pressure (static negative pressure) in the ink delivery tube  160 . 
     Next, gas is drawn into the internal bladder  220 , allowing ink to be consumed, that is, drawn out, through gas-liquid exchange while the absorbent material pieces  130  and  140  keep the position of the gas-liquid interface L at about the same level, and keep the internal negative pressure substantially constant (second state: range B in FIG. 7, ( a )). Then, the ink remaining in the capillary pressure generating member holding chamber  110  is consumed (range C in FIG. 7, ( a )).As described above, the ink jet head cartridge in this embodiment goes through the stage (first stage) in which the ink in the internal bladder  220  is used without the introduction of the outside air into the internal bladder  220 . Therefore, the only requirement to be considered regarding the internal volume of the ink storing container  201  is the amount of the air introduced into the internal bladder  220  during the connection. Therefore, the ink jet head cartridge in this embodiment has merit in that it can compensate for the ambient changes, for example, temperature change, even if the requirement regarding the internal volume of the ink storing container  201  is relaxed. 
     Further, in whichever period among the aforementioned periods A, B, and C, in FIG. 7, ( a ), the ink storing container  201  is replaced, it is assured that the proper amount of negative pressure is generated, and therefore, ink is reliably supplied. In other words, in the case of the ink jet head cartridge in this embodiment, the ink in the ink storing container  201  can be almost entirely consumed. In addition, air may be present in the joint pipe  180  and/or joint opening  230  when the ink container unit  200  is replaced, and the ink storing container  201  can be replaced regardless of the amounts of the ink retained in the absorbent material pieces  130  and  140 . Therefore, it is possible to provide an ink jet head cartridge which allows the ink storing container  201  to be replaced without relying on an ink remainder detection mechanism; in other words, the ink jet head cartridge in this embodiment does not need to be provided with an ink remainder detection mechanism. 
     At this time, the aforementioned ink consumption sequence will be described from a different viewpoint, referring to FIG. 7, ( b ). 
     FIG. 7, ( b ) is a graph for describing the above described ink consumption sequence. In FIG. 7, ( b ), the axis of abscissas represents the elapsed time, and the axis of ordinates represents the cumulative amount of the ink drawn out of the ink storing container, and the cumulative amount of the air drawn into the internal bladder  220 . It is assumed that the rate at which the ink jet head unit  160  is provided with ink remains constant throughout the elapsed time. 
     The ink consumption sequence will be described from the angles of the cumulative amount of the ink drawn out of the ink containing portion, and the cumulative amount of the air drawn into the internal bladder  220 , shown in FIG. 7, ( b ). In FIG. 7, ( b ), the cumulative amount of the ink drawn out of the internal bladder  220  is represented by a solid line ( 1 ), and the cumulative amount of the air drawn into the ink containing portion is represented by a solid line ( 2 ). A period from a time t 0  to t 1  corresponds to the period A, or the period before the gas-liquid exchange begins, in FIG. 7, ( a ). In this period A, the ink from the absorbent material piece  140  and internal bladder  220  is drawn out of the head while balance is maintained between the absorbent material piece  140  and  220 , as described above. 
     Next, the period from time t 1  to time t 2  corresponds to the gas-liquid exchange period (period B) in FIG. 7, ( b ). In this period B, the gas-liquid exchange continues according to the negative pressure balance, as described above. As air is introduced into the internal bladder  220  (which corresponds to the stepped portions of the solid line ( 2 )), as indicated by the solid line ( 1 ) in FIG. 7, ( b ), ink is drawn out of the internal bladder  220 . During this process, it does not occur that ink is always drawn out of the internal bladder  220  by an amount equal to the amount of the introduced air. For example, sometimes, ink is drawn out of the internal bladder  220  a certain amount of time after the air introduction, by an amount equivalent to the amount of the introduced air. As is evident from FIG. 7, ( b ), the occurrence of this kind of reaction, or the timing lag, characterizes the ink jet head cartridge in this embodiment in comparison to an ink jet head cartridge which does not have an internal ink bladder ( 220 ), and the ink containing portion of which does not deform. As described above, this process is repeated during the gas-liquid exchange period. As the ink in the internal bladder  220  continues to be drawn out, the relationship between the amounts of the air and ink in the internal bladder  220  reverses at a certain point in time. 
     The period after the time t 2  corresponds to the period (range C) after the gas-liquid exchange period in FIG. 7, ( a ). In this range C, the internal pressure of the internal bladder  220  becomes substantially the same as the atmospheric pressure as stated before. As the internal pressure of the internal bladder  220  gradually changes toward the atmospheric pressure, the initial state (pre-usage state) is gradually restored by the resiliency of the internal bladder  220 . However, because of the so-called buckling, it does not occur that the state of the internal bladder  220  is completely restored to its initial state. Therefore the final amount Vc of the air drawn into the internal bladder  220  is smaller than the initial internal volume of the internal bladder  220  (V&gt;Vc). Even in the state within the range C, the ink in the internal bladder  220  can be completely consumed. 
     As described above, the structure of the ink jet head cartridge in this embodiment is characterized in that the pressure fluctuation (amplitude γ in FIG. 7, ( a )) which occurs during the gas-liquid exchange in the ink jet head cartridge in this embodiment is greater compared to that in an ink jet head cartridge which employs a conventional ink container system in which gas-liquid exchange occurs. 
     The reason for this characteristic is that before the gas-liquid exchange begins, the internal bladder  220  is deformed, and kept deformed, by the drawing of the ink from inside the internal bladder  220 . 
     Therefore, the resiliency of the internal bladder material continuously generates such force that works in the direction to move the wall of the internal bladder  220  outward. As a result, the amount of the air which enters the internal bladder  220  to reduce the internal pressure difference between the absorbent material piece  140  and internal bladder  220  during the gas-liquid exchange often exceeds the proper amount, as described, increasing the amount of the ink drawing out of the internal bladder. 220  into the external shell  210 . On the contrary, if the ink container unit  200  is structured so that the wall of the ink containing portion does not deform as does the wall of the internal bladder  220 , ink is immediately drawn out into the negative pressure controlling chamber unit  100  as soon as a certain amount of air enters the ink containing portion. 
     For example, in 100% duty mode (solid mode), a large amount of ink is ejected all at once from the ink jet head unit  160 , causing ink to be rapidly drawn out of the negative pressure controlling chamber unit  100  and ink storing container  201 . However, in the case of the ink jet head cartridge in this embodiment, the amount of the ink drawn out through gas-liquid exchange is relative large, improving the reliability, that is, eliminating the concern regarding the interruption of ink flow. 
     Also, according to the structure of the ink jet head cartridge in this embodiment, ink is drawn out with the internal bladder  220  remaining deformed inward, providing thereby an additional benefit in that the structure offers a higher degree of buffering effect against the vibration of the carriage, ambient changes, and the like. 
     As described above, according to the structure of the ink jet head cartridge in this embodiment, the slight changes in the negative pressure can be eased by the internal bladder  220 , and even when air is present in the internal bladder  220 , for example, during the second stage in the ink delivery, the ambient changes such as temperature change can be compensated for by a method different from the conventional methods. 
     Next, referring to FIG. 8, a mechanism for assuring that even when the ambient condition of the ink jet head cartridge illustrated in FIG. 2 changes, the liquid within the unit remains stable will be described. In the following description, the absorbent material pieces  130  and  140  may be called a capillary force generating member. 
     As the air in the internal bladder  220  expands due to decrease in the atmospheric pressure and/or increase in the temperature, the walls or the like portions of the internal bladder  220 , and the liquid surface in the internal bladder  220 , are subjected to pressure. As a result, not only does the internal volume of the internal bladder  220  increase, but also a portion of the ink in internal bladder  220  flows out into the negative pressure controlling chamber shell  110  from the internal bladder  220  through the joint pipe  180 . However, since the internal volume of the internal bladder  220  increases, the amount of the ink that flows out into the absorbent material piece  140  in the case of this embodiment is substantially smaller compared to a case in which the ink storage portion is undeformable. 
     As described above, the aforementioned changes in the atmospheric pressure ease the negative pressure in the internal bladder  220  and increase the internal volume of the internal bladder  220 . Therefore, initially, the amount of the ink which flows out into the negative pressure controlling chamber shell through the joint opening  230  and joint pipe  180  as the atmospheric pressure suddenly changes is substantially affected by the resistive force generated by the internal bladder wall as the inward deformation of the wall portion of the internal bladder  220  is eased, and by the resistive force for moving the ink so that the ink is absorbed by the capillary force generating member. 
     In particular, in the case of the structure in this embodiment, the flow resistance of the capillary force generating members (absorbent material pieces  130  and  140 ) is greater than the resistance of the internal bladder  220  against the restoration of the original state. Therefore, as the air expands, initially, the internal volume of the internal bladder  220  increases. Then, as the amount of the air expansion exceeds the maximum amount of the increase in the internal volume of the internal bladder  220  afforded by the internal bladder  220 , ink begins to flows from within the internal bladder  220  toward the negative pressure controlling chamber shell  110  through the joint opening  230  and joint pipe  180 . In other words, the wall of the internal bladder  220  functions as the buffer against the ambient changes, and therefore, the ink movement in the capillary force generating member calms down, stabilizing the negative pressure adjacent to the ink delivery hole  165 . 
     Also according to this embodiment, the ink which flows out into the negative pressure controlling chamber shell  110  is retained by the capillary force generating members. In the aforementioned situation, the amount of the ink in the negative pressure controlling chamber shell  110  increases temporarily, causing the gas-liquid interface to rise, and therefore, in comparison to when the internal pressure is stable, the internal pressure temporarily becomes slightly positive, as it is initially. However, the effect of this slightly positive internal pressure upon the characteristics of a liquid ejection recording means such as the ink jet head unit  160 , in terms of ejection, creates no practical problem. As the atmospheric pressure returns to the normal level (base unit of atmospheric pressure), or the temperature returns to the original level, the ink which leaked out into the negative pressure controlling chamber shell  110  and has been retained in the capillary force generating members, returns to the internal bladder  220 , and the internal bladder  220  restores its original internal volume. 
     Next, the basic action in the stable condition restored under such atmospheric pressure that has changed after the initial operation will be described. 
     What characterizes this state is the amount of the ink drawn out of the internal bladder  220 , as well as that the position of the interface between the ink retained in the capillary force generating member, and the gas, changes to compensate for the fluctuation of the negative pressure resulting from the fluctuation of the internal volume of the internal bladder  220  itself. Regarding the relationship between the amount of the ink absorbed by the capillary force generating member and the ink storing container  201 , all that is necessary from the viewpoint of preventing ink from leaking from the air vent or the like during the aforementioned decrease in the atmospheric pressure and temperature change, is to determine the maximum amount of the ink to be absorbed by the negative pressure controlling chamber shell  110  and the amount of the ink to be retained in the negative pressure controlling chamber shell  110  while the ink is supplied from the ink storing container  201 , in consideration of the amount of the ink which flows out of the ink storing container  201  under the worst conditions, and then, to give the negative pressure controlling chamber shell  110  an internal volume sufficient for holding the capillary force generating members, the sizes of which match the aforementioned amount of ink under the worst conditions, and the maximum amount of the ink to be absorbed. 
     In FIG. 8, ( a ), the initial volume of the internal space (volume of the air) of the internal bladder  220  before the decrease in the atmospheric pressure, in a case in which the internal bladder  220  does not deform at all in response to the expansion of the air, is represented by the axis of abscissas (X), and the amount of the ink which flowed out as the atmospheric pressure decreased to a value of P (0&lt;P&lt;1) is represented by the axis of ordinates, and their relationship is depicted by a dotted line ( 1 ). 
     The amount of the ink which flows out of the internal bladder  220  under the worst conditions may be estimated based on the following assumption. For example, a situation in which the amount of the ink which flows out of the internal bladder  220  becomes the maximum when the lowest level to which the value of the atmospheric pressure decreases is 0.7, is when the volume of the ink remaining in the internal bladder  220  equals 30% of the volumetric capacity VB of the internal bladder  220 . Therefore, presuming that the ink below the bottom end of the wall of the internal bladder  220  is also absorbed by the capillary force generating members in the negative pressure controlling chamber shell  110 , it may be expected that the entirety of the ink remaining in the internal bladder  220  (equals in volume to 30% of the volumetric capacity VB) leaks out. 
     On the contrary, in this embodiment, the internal bladder  220  deforms in response to the expansion of the air. In other words, compared to the internal volume of the internal bladder  220  before the expansion, the internal volume of the internal bladder  220  is greater after the expansion, and the ink level in the negative pressure controlling chamber shell  110  changes to compensate for the fluctuation of the negative pressure in the internal bladder  220 . Under the stable condition, the ink level in the negative pressure controlling chamber shell  110  changes to compensate for the decrease in the negative pressure in the capillary force generating members, in comparison to the negative pressure in the capillary force generating members before the change in the atmospheric pressure, caused by the ink from the internal bladder  220 . In other words, the amount of the ink which flows out decreases in proportion to the amount of the expansion of the internal bladder  220 , as depicted by a solid line ( 2 ). As is evident from the dotted line ( 1 ) and solid line ( 2 ), the amount of the ink which flows out of the internal bladder  220  may be estimated to be smaller compared to that in the case in which the internal bladder  220  does not deform at all in response to the expansion of the air. The above described phenomenon similarly occurs in the case of the change in the temperature of the ink container, except that even if the temperature increases approximately 50 degrees, the amount of the ink outflow is smaller than the aforementioned amount of the ink outflow in response to the atmospheric pressure decrease. 
     As described above, the ink container in accordance with the present invention can compensate for the expansion of the air in the ink storing container  201  caused by the ambient changes not only because of the buffering effect provided by the negative pressure controlling chamber shell  110 , but also because of the buffering effect provided by the ink storing container  201  which is enabled to increase in its volumetric capacity to the maximum value at which the shape of the ink storing container  201  becomes substantially the same as the shape of the internal space of the external shell  210 . Therefore, it is possible to provide an ink supplying system which can compensate for the ambient changes even if the ink capacity of the ink storing container  201  is substantially increased. 
     FIG. 8, ( b ) schematically shows the amount of the ink drawn out of the internal bladder  220  and the internal volume of the internal bladder  220 , in relation to the length of the elapsed time, when the ambient pressure is reduced from the normal atmospheric pressure to the pressure value of P (0&lt;P&lt;1). In 
     FIG. 8, ( b ), the initial volume of the air is VA 1 , and a time t 0  is a point in time at which the ambient pressure is the normal atmospheric pressure, and from which the reduction in the ambient pressure begins. The axis of abscissas represents time (t) and the axis of ordinates represents the amount of the ink drawn out of the internal bladder  220  and the internal volume of the internal bladder  220 . The changes in the amount of the ink drawn out of the internal bladder  220  in relation to the elapsed time is depicted by a solid line ( 1 ), and the change in the volume of the internal bladder  220  in relation to the elapsed time is depicted by a solid line ( 2 ). 
     As shown in FIG. 8, ( b ), when a sudden ambient change occurs, the compensation for the expansion of the air is made mainly by the ink storing container  201  before the normal state, in which the negative pressure in the negative pressure controlling chamber shell  110  balances with the negative pressure in the ink storing container  201 , is finally restored. Therefore, at the time of sudden ambient change, the timing with which the ink is drawn out into the negative pressure controlling chamber shell  110  from the ink storing container  201  can be delayed. 
     Therefore, it is possible to provide an ink supplying system capable of supplying ink under the stable negative pressure condition during the usage of the ink storing container  201 , while compensating the expansion of the air introduced in the ink storing container  201  through gas-liquid exchange, under various usage conditions. 
     According to the ink jet head cartridge in this embodiment, the volumetric ratio between the negative pressure controlling chamber shell  110  and internal bladder  220  can be optimally set by optionally selecting the material for the capillary force generating members (ink absorbent pieces  130  and  140 ), and the material for the internal bladder  220 ; even if the ratio is greater than 1:2, practical usage is possible. In particular, when emphasis needs to be placed on the buffering effect of the internal bladder  220 , all that is necessary is to increase, within the range in which the elastic deformation is possible, the amount of the deformation of the internal bladder  220  during the gas-liquid exchange, relative to the initial state. 
     As described above, according to the ink jet head cartridge in this embodiment, although the capillary force generating members occupies only a small portion of the internal volume of the negative pressure controlling chamber shell  110 , it is still effective to compensate for the changes in the ambient condition, by synergistically working with the structure of the negative pressure controlling chamber shell  110 . 
     Referring to FIG. 2, in the ink jet head cartridge in this embodiment, the joint pipe  180  is located adjacent to the bottom end of the negative pressure controlling chamber shell  110 . This arrangement is effective to reduce the uneven distribution of the ink in the absorbent material pieces  130  and  140  in the negative pressure controlling chamber shell  110 . This effect will be described below in detail. 
     The ink from the ink container unit  200  is supplied to the ink jet head unit  160  through the joint opening  230 , absorbent material piece  130 , and absorbent material piece  140 . However, between the joint opening  230  and ink delivery tube  165 , the ink takes a different path depending on the situation. For example, the shortest path, that is, the path taken by the ink in a situation in which the ink is directly supplied, is substantially different from the path taken in a situation in which the ink goes, first, to the top of the absorbent material piece  140  due to the rise of the liquid surface of the absorbent material piece  140  caused by the aforementioned ambient changes. This difference creates the aforementioned uneven ink distribution, which sometimes affects recording performance. This variation in the ink path, that is, the difference in the length of the ink path,;can be reduced to reduce the unevenness of the ink distribution, by positioning the joint pipe  180  adjacent to the absorbent material piece  140 , as it is according to the structure of the ink jet head cartridge in this embodiment, so that the unevenness in the recording performance is reduced. Thus, it is desired that the joint pipe  180  and joint opening  230  are placed as close as possible to the top portion. 
     However, in consideration of the need to provide the buffering performance, they are placed at reasonably high positions as they are in this embodiment. These positions are optionally chosen in consideration of various factors, for example, the absorbent material pieces  130  and  140 , ink, amount by which ink is supplied, amount of ink, and the like. 
     In this embodiment, the absorbent material piece  140  which generates a, capillary force with a value of P 1  and the absorbent material piece  130  which generates a capillary force with a value of P 2  are placed in the negative pressure controlling chamber shell  110 , in contact with each other, in a compressed state, generating a capillary force with a value of PS. The relationship in the strength among these capillary forces is: P 2 &lt;P 1 &lt;PS. In other words, the capillary force generated at the interface  113   c  is the strongest, and the capillary force generated in the absorbent material piece  130 , or the absorbent material piece on the top side, is the weakest. Because the capillary force generated at the interface  113   c  is the strongest, and the capillary force generated in the absorbent material piece  130 , or the absorbent material piece on the top side, is the weakest, even if the ink supplied through the joint opening  230  flows into the absorbent material piece  130  on the top side past the interface  113   c , the ink is pulled with strong force toward the interface  113   c , and moves back toward the interface  113   c . With the presence of this interface  113   c , it does not occur that the path J forms a line through both the absorbent material pieces  140  and  130 . For this reason, in addition to the fact that the position of the joint opening  230  is higher than that of the supply opening  131 , the difference in length between the path K and path J can be reduced. Therefore, it is possible to reduce the difference in the effect which ink receives from the absorbent material piece  140 , which occurs as the ink path through the absorbent material pieces  140  varies. 
     Further, in this embodiment, the ink absorbing member as the negative pressure generating member placed in the negative pressure controlling chamber shell  110  comprises two pieces  130  and  140  of absorbent material, which are different in capillary force. The piece with stronger capillary force is used as the piece for the bottom side. The positioning of the joint pipe  180  below, and adjacent to, the interface  113   c  between the absorbent material pieces  130  and  140  assures that the shifting of the ink path is controlled while providing a reliable buffering zone. 
     As for an ink delivery port, the ink delivery port  131  located at the approximate center of the bottom wall of the negative pressure controlling chamber shell  110  is described as an example. However, the choice is not limited to the ink delivery port  131 ; if necessary, an ink delivery port may be moved away from the joint opening  230 ; in other words, it may be positioned at the left end of the bottom wall, or adjacent to the left sidewall. With such modifications, the position of the ink jet head unit  160 , with which the holder  150  is provided, and the position of the ink delivery tube  165 , may also be correspondingly altered to the left end of the bottom wall, or the adjacency of the left sidewall. 
     &lt;Valve Mechanism&gt; 
     Next, referring to FIG. 9, the valve mechanism provided inside the joint opening  230  of the above described ink container unit  200  will be described. 
     FIG. 9, (a), is a front view of the relationship between the second valve body  260   b  and valve plug  261 ; FIG. 9, ( b ), a lateral and vertically sectional view of the second valve body  260   b  and valve plug  261  illustrated in FIG. 9, ( a ); FIG. 9, ( c ), a front view of the relationship between the second valve body  260   b , and the valve plug  260  which has slightly rotated; and FIG. 9, ( d ), is a lateral and vertically sectional view of the second valve body  260   b  and valve plug  260  illustrated in FIG. 9, ( c ). 
     As shown in FIG. 3, FIG. 9, ( a ), and FIG. 9, ( b ), the front end of the joint opening  230  is elongated in one direction, enlarging the cross-sectional area of the opening, to enhance the ink supplying performance of the ink storing container  201 . However, if the joint opening  230  is widened in the width direction perpendicular to the lengthwise direction of the joint opening  230 , the space which the ink storing container  201  occupies increases, leading to increase in the apparatus size. This configuration is particularly effective when a plurality of ink containers are placed side by side in terms of the widthwise direction (direction of the scanning movement of the carriage), in parallel to each other, to accommodate the recent trends, that is, colorization and photographic printing. Therefore, in this embodiment, the shape of the cross section of the joint opening  230 , that is, the ink outlet of the ink storing container  201  is made oblong. 
     In addition, in the case of the ink jet head cartridge in this embodiment, the joint opening  230  has two roles: the role of supplying the external shell  210  with ink, and the role of guiding the atmospheric air into the ink storing container  201 . Thus, the fact that the shape of the cross section of the joint opening  230  is oblong in the direction parallel to the gravity direction makes it easier to give the top and bottom sides of the joint opening  230  different functions, that is, that is, to allow the top side to essentially function as the air introduction path, and the bottom side to essentially function as the ink supply path, assuring that gas-liquid exchange occurs flawlessly. 
     As described above, as the ink container unit  200  is installed, the joint pipe  180  of the negative pressure controlling chamber unit  100  is inserted into the joint opening  230 . As a result, the valve plug  261  is pushed by the valve activation projection  180   b  located at the end of the joint pipe  180 . Consequently, the valve mechanism of the joint opening  230  opens, allowing the ink in the ink storing container  201  to be supplied into the negative pressure controlling chamber unit  100 . Even if the valve activation projection  180   b  misses the exact center of the valve plug  261  as it comes into contact with the valve plug  261  to push it, because of the attitude of the ink container unit  200  when the ink container unit  200  is engaged with the joint opening  230 , the twisting of the valve plug  261  can be avoided because the cross section of the end portion of the sealing projection  180   a  placed on the peripheral surface of the joint pipe  180  is semicircular. Referring to FIGS. 9, ( a ) and ( b ), in order to allow the valve plug  261  to smoothly slide during the above process, a clearance  266  is provided between the joint sealing surface  260  in the joint opening  230 , and the circumference of the first valve body side of the valve plug  261 . 
     In addition, at the end of the joint pipe  180 , at least the top portion has an opening, and therefore, when the joint pipe  180  is inserted into the joint opening  230 , there is no hindrance to the formation of the essential air introduction path through the top sides of the joint pipe  180  and joint opening  230 . Therefore, an efficient gas-liquid exchange is possible. On the contrary, during the removal of the ink container unit  200 , as the joint pipe  180  separates from the joint opening  230 , the valve plug  261  is slid forward, that is, toward the first valve body  260   a , by the resilient force which it receives from the resilient member  263 . As a result, the seal portion  264  of the first valve body  260   a  and the valve plug  261  engage with each other, closing the ink supply path, as shown in FIG. 9, ( d ). 
     FIG. 10 is a perspective view of the end portion of the joint pipe  180 , and depicts an example of the shape of the end portion. As shown in FIG. 10, the top side of the end portion of the joint pipe  180  with the aforementioned oblong cross section is provided with an opening  181   a , and the bottom side of the end portion of the joint pipe  180  is provided with an opening  181   b . The bottom side opening  181   b  is an ink path, and the top side opening  181   a  is an air path, although ink is occasionally passed through the top side opening  181   a.    
     The value of the force applied to the valve plug  261  by the resilient member to keep the valve plug  261  in contact with the first valve body  260   a  is set so that it remains substantially the same even if a pressure difference occurs between the inside and outside of the ink storing container  201  due to the changes in the environment in which the ink storing container  201  is used. If the valve plug  261  is returned to the closed position after the above described ink container unit  200  is used at high altitude with an atmospheric pressure of 0.7, and then, the ink container unit  200  is carried to an environment with an atmospheric pressure of 1.0, the internal pressure of the ink storing container  201  becomes lower than the atmospheric pressure. As a result, the valve plug  261  is pressed in the direction to open the valve mechanism. In the case of this embodiment, the force FA applied to the valve plug  261  by the atmospheric pressures is calculated by the following formula: 
     
       
           FA =1.01×105 ( N/m   2 ) (= 1.0),   
       
     
     whereas the force FB applied to the valve plug  261  by the gas in the ink container is obtained from the following formula: 
     
       
           FB =0.709×10 5 ( N/m   2 ) (= 0.7).   
       
     
     The constant force FV necessary to be generated by the resilient member to keep the valve plug  261  in contact with the valve body must satisfy the following requirement: 
     
       
           FV −( FA−FB )&gt;0. 
       
     
     In other words, in this embodiment, 
     
       
           FV &gt;1.01×10 5 −0.709×10 5 =0.304×10 5  ( N/m   2 ). 
       
     
     This value applies to a situation in which the valve plug  261  is in contact with the first valve body  260   a , under pressure. When the valve plug  261  is apart from the first valve body  260   a , that is, after the amount of the deformation of the deformation of the resilient member  26 e for generating the force applied to the valve plug  261  has increased, the value of the force applied to the valve plug  261  by the resilient member  263  in the direction to push the valve plug  261  toward the first valve body  260   a  is greater, which is evident. 
     In the case of the above described valve structure, there is a possibility that it suffers from a phenomenon called “twisting”. More specifically, the coefficient of friction at the interface between the valve activation projection  180   b  and valve plug  261  sometimes increases due to the adhesion of solidified ink or the like. If such a situation occurs, the valve plug  261  fails to slide on the surface of the valve activation projection  180   b  upon which it was intended to slide. As a result, as the ink container unit  200  is rotationally moved, the valve plug  261  strokes while being pushed, being thereby twisted, in the upward direction in the drawing by the valve activation projection  180   b.    
     Thus, hereinafter, the configuration of a valve capable of compensating for the effect of the twisting (clogging) phenomenon upon the sealing performance will be described, along with the comparative examples. 
     FIG. 11 shows an example of a valve mechanism, which is compared with the valve mechanism in this embodiment. FIGS. 12 and 13 show the twisting in the valve mechanism illustrated in FIG. 11, and the state in which the joint is sealed. In the case of the comparative example in FIG. 11, a clearance  506  provided between a valve plug  501  with an oblong cross section and a second valve body  500   b  to facilitate the stroking of the valve plug  501 , is even. The valve plug  501  is pressed upon a first valve body  500   a  by a resilient member  503  to keep the sealing surface  501   c  of the valve plug  501 , that is, the surface of the tapered, second valve body side of the valve plug  501 , tightly in contact with the tapered seal portion  500   c  of the first valve body  500   a , to seal a joint opening  530 . Referring to FIG. 12, if the above described twisting phenomenon occurs in the above described structure of the comparative example, the valve plug  501  makes contact with the second valve body  500   b  at two areas, that is, a contact surface  510   a  and a contact surface  511   b . Representing the distance between these two contact surfaces, and the amount of the clearance, with X and Y, the twist angle θ is: θ=tan −1  ( 2 Y/X). Assuming that the clearance remains the same, the greater the distance X between the two contact surfaces, the smaller the value of the twist angle θ. 
     In the case of this comparative example, however, the length X of the contact surface is relatively small (compared to the valve plug diameter, for example), rendering the twist angle θ relatively large. In other words, in order to rectify the twisting, a rotational motion with a relatively large angle is necessary. Therefore, it is evident that the probability that the twisting is rectified after its occurrence is small. 
     Referring to FIG. 13, if a contact is made with the first valve body  500   a  without rectification of the twisting, the tapered seal portion  501   c  of the valve plug  501  becomes different in the contact radius from the tapered seal portion  500   c  of the first valve body  500   a . As a result, the contact portions fail to make perfect contact with each other, allowing ink leakage to occur. 
     The second valve body  500   b  and a valve cover  502  are welded by ultrasonic waves. The valve cover in the comparative example is a simple flat one, raising the possibility that the ultrasonic waves causes misalignment, that is, the accuracy with which the center hole of the valve cover  502 , though which the sliding axis  501   a  of the valve plug  501  is put, varies, making it necessary to enlarge the center hole of the valve cover  502  to prevent the wall of the hole of the valve cover  502  from contacting the sliding axis  501   a  of the valve plug  501 . Consequently, it becomes difficult to reduce the size of the resilient member  503 , and therefore, it becomes difficult to reduce the size of the entirety of the valve mechanism, because the minimum diameter of the resilient member  503  is dependent upon the diameter of the hole of the valve cover  502 . 
     In contrast to the above described comparative example, the valve mechanism in this embodiment has the following structure. FIG. 14 shows the valve mechanism in this embodiment of the present invention, and FIGS. 15 and 16 show the twisting of the valve mechanism in FIG. 14, and the state of the relationship between the two seal portions. Referring to FIG. 14, in this embodiment, the valve plug  261  is tapered in terms of the stroke direction (rightward direction in the drawing); the diameter (at least, length of the major axis) of the valve plug  261  gradually reduces in terms of the rightward direction. The interior wall of the second valve body  260   b  is tapered so that its diameter gradually increases in terms of the stroke (rightward) direction. With this structural arrangement, in order for the valve plug  261  to come into contact with the second valve body  260   b  at a position equivalent to the contact surface  511   b  in the, comparative example in FIG. 12 when the valve plug  261  is twisted, a substantially larger angle is necessary, and before the angle of the valve plug  261  reaches this substantially large angle, the sliding axis of the valve plug  261  comes into contact with the wall of the hole of the valve cover  262  (FIG.  15 ). Thus, the length of X of the contact surface can be set to be longer, making it possible to reduce the amount of the twist angle θ. Therefore, even if the twisted valve plug  261  is placed in contact with the first valve body  500   a  without being rectified in its twist as shown in FIG. 16, the twist angle θ is extremely small compared to the comparative example; the interfaces between the seal portion  265  of the valve plug  261  and the seal portion  264  of the first valve body  260   a  are better sealed. 
     It should be noted here that representing the length of the contact surface, and the clearance between the sliding axis of the valve plug  261  and the hole of the valve cover  26 , 0   b , with X and Y 1 : 
     
       
         θ=tan −1  (Y 1 +Y 2 /X). 
       
     
     The valve cover  252  is provided with a valve cover welding guide  262   a , which is a stepped portion (depth of penetration by the valve cover: 0.8 mm), and comes in contact with the edge of the second valve body  260   b  as the valve cover  252  is pushed into the second valve body  260   b . Therefore, the hole of the valve cover  262 , through which the sliding axis of the valve plug  261  is put, is rendered smaller than that in the comparative example. In other words, the provision of the valve cover  262  with the welding guide  262   a  reduces the amount of the misalignment between the second valve body  260   b  and the valve cover  262  which is caused by the vibrations occurring during the welding between the two components, and therefore, the accuracy with which the hole of the valve cover  262  is positioned is improved. Thus, it becomes possible to reduce the diameter of the hole of the valve cover  262 , which makes it possible to reduce the diameter of the resilient member  263 . Consequently, it becomes possible to reduce the size of the valve mechanism. Further, even if force is applied by the valve plug  261  through the sliding axis of the valve plug  261  due to the twisting of the valve plug  261 , the rigidity of the valve cover  262  is secured by the valve cover welding guide  262   a.    
     The ridge line portion of the hole of the valve cover  262  is provided with an R portion  262   b . This R portion  262   b  is provided at only the ridge line on the non-welding surface side (right-hand side in the drawing). With the provision of this arrangement, the friction between the sliding axis of the valve plug  261  and the valve cover  262  during the movement, in particular, the opening movement, of the valve plug  261  in the twisted state, can be reduced. 
     The end portion of the valve plug  261 , which comes into contact with the first valve body  260   a , is a seal portion  265  of the valve plug  261 , which has a flat surface. In contrast, the portion of the first valve body  260   a , which the seal portion  265  of the valve plug  261  contacts, is the seal portion  264  of the first valve body sealing portion  264 , that is, the surface of a piece of elastomer  267  placed on the interior surface of the first valve body  260   a . Flattening the seal portion of the valve plug  261  and first valve body  260   a  equalizes the contact radii of the valve plug  261  having the oblong cross section, with the R portion of the first valve body  260   a ; perfect contact is made between the valve plug  261  and first valve body  260   a . In addition, the seal portion  264  of the first valve body  260   a  is shaped like a tongue sticking out of a mouth, assuring further that the interfaces between the two components are flawlessly sealed. 
     In the case of a valve mechanism structured as described above, if clearance is provided between the valve plug  261  and second valve body  260   b , it occurs sometimes that the valve plug  261  rotates about its axis, within the second valve body  260   b , during the installation or removal of the ink container unit  200 , as shown in FIG. 9, ( c ). In this embodiment, however, even if the valve plug  261  is rotated about its axis to the maximum angle, and then, is pressed upon the first valve body  260   a  while remaining in the maximumly rotated state, the contact between the valve plug  261  and first valve body  260   a  is by their seal portions  265  and  264 , respectively; in other words, the contact is made surface to surface. Therefore, it is assured that the valve mechanism is airtightly sealed. 
     In addition, since the joint opening  230  and valve mechanism are shaped so that their cross sections become oblong, the rotational angle of the valve plug  261  during the sliding of the valve plug  261  can be minimized, and also, the valve response can be improved. Therefore, it is possible to assure that the valve mechanism of the joint opening  230  flawlessly functions in terms of sealing performance. Further, since the joint opening  230  and valve mechanism are shaped so that their cross sections become oblong, the projection  180   a  for sealing, provided on the peripheral surface of the joint opening  230 , and the valve plug  261 , swiftly slide through the joint opening  230  during the installation or removal of the ink container unit  200 , assuring that the connecting operation ensues smoothly. 
     Referring to FIG. 10, the end portion of the joint opening  230 , which makes contact with the valve plug  261 , comprises two symmetrical absorbent material pieces  180   b . There are the opening  181   a  for gas-liquid exchange, on the top side of the end portion of the joint opening  230 , and the opening  181   b  for supplying liquid, on the bottom side. Therefore, a study was made regarding the idea of providing the valve plug  261  with a pair of contact ribs  310  as counterparts to the projection  180   b , which are to be positioned on the areas excluding the sealing portion  265  which is placed tightly in contact with the sealing portion  264  of the first valve body  260   a , as shown in FIGS. 17, ( c ) and ( d ). However, during the opening of the valve, the valve plug  261  is pushed back by the force from the resilient member  263 , and therefore, the rib portions are required to have a certain amount of rigidity, high enough to prevent the deformation of the rib portions. In addition, regarding the positioning and shapes of the contact rib portions, it is required, from the viewpoint of reliability, that even if the positions of the contact rib portions of the valve plug  261  shift in the radial direction of the sliding axis of the valve plug  261 , relative to the two valve activation projections  180   b  of the joint pipe  180 , the moments which generate at the two contact rib portions which oppose each other across the sliding axis  261   a , cancel each other. Therefore, in this embodiment, the valve plug  261  is provided with a circular rib  311  (0.6 mm in width and 1.3 mm in height), which is similar in cross section to the joint pipe  180  which has the oblong cross section, as shown in FIGS. 17, ( a ) and ( b ). In other words, the surface of the valve plug  261 , on the first valve body side, excluding the sealing portion  265  which is placed in contact with the sealing portion  264  of the first valve body  500   a , is provided with an oblong recess  311   a , the center of which coincides with the axial line of the valve plug  261 . This structure provides the valve plug  261  with the strength and reliability required when the valve activation projection  180   b  makes contact with the valve plug  261 . Making the rib circular, and making the center of the recess coincide with the axial line of the valve plug  261 , could improve the moldability of the valve plug  261 . From this viewpoint, regarding moldability, it is desired that the base portion of the circular rib, on the recess side, be given a minuscule curvature. 
     Referring to FIGS. 2 and 3, during the assembly of the ink container unit  200 , the ID member  250  is attached by welding and interlocking, after the valve mechanism comprising the first valve body  260   a  and second valve body  260   b  is inserted into the ink delivery opening of the ink storing container  201 . In particular, the internal bladder  220  is exposed at the edge of the opening of the ink delivery opening of the ink storing container  201 , and the flange  268  of the first valve body  260   a  of the valve mechanism is welded to this exposed portion  221   a  of the internal bladder  220 . Thereafter, the ID member  250  is welded at the location of the flange  268 , and is interlocked with the engagement portions  201   a  of the container external shell  210 . 
     In the case of this type of assembly, for example, the flange  508  of the first valve body, to which the ID member  550  is attached, is flat as it is in the case of the comparative example illustrated in FIG. 11; the elastomer layer  567  is not exposed at the edge of the ink delivery opening with which the ID member  550  is provided, and:therefore, there is a possibility that seal leakage may occur during the process, illustrated in FIG. 5, for connecting the joint pipe  180 . Thus, in this embodiment, the welding surface of the flange  508  of the first valve body, to which the ID member  550  is welded, and which was in the same plane as the plane of the opening of the joint opening  530 , has been moved in the direction opposite to the container installation direction. In other words, the first valve body flange  268  is positioned so that when the ID member  250  is glued to the first valve body flange  268  as shown in FIGS. 2,  14 , and the like, the plane of the external surface of the ID member  250  coincides with the plane of the opening of the joint opening  230 . This structural arrangement assures the presence of the elastomer layer  267  inside the ink delivery hole with which the ID member  250  is provided, rendering the valve mechanism into a highly reliable one which allows no possibility of the aforementioned seal leakage. Further, since the first valve body flange  268  has been moved away from the plane of the opening of the joint opening  230 , the opening portion of the joint opening  230  protrudes from the surface of the first valve body flange  268 . Therefore, when the ID member  250  is attached, the position of the ID member is guided by the opening portion of the joint opening  230 , making it easier to accurately position the ID member  250 . 
     Each ink storing container  201  of the ink container unit  200  in this embodiment is installed into the holder  150 , and supplies the correspondent negative pressure controlling chamber shell  110  with ink through the joint pipe  180  and the valve mechanism of the joint opening  230  of the container  201 . The holder  150  holding the ink storing containers 20 l as described above is mounted on the carriage of a serial scanning type recording apparatus (FIG. 24) and is moved back and forth in the direction parallel to the plane of recording paper. In this case, it is desired from the viewpoint of product reliability that countermeasures are taken to prevent the state of the sealing between the interior surface of the joint opening  230  of the ink storing container  201 , and the exterior surface of the joint pipe  180  of the negative pressure controlling chamber shell  110 , from deteriorating due to the twisting which is caused at the joint by the run out of the axis of the joint pipe  180 , the shifting of the ink storing containers  201 , and the like, which occur as the carriage is moved back and forth. 
     Therefore, in this embodiment, the thickness of the elastomer layer  267  in the first valve body  260   a  of the valve mechanism-shown in FIGS. 2,  14 , and the like, is made greater than the minimum requirement for sealing between the first valve body  260   a  and joint pipe  180 , so that the run out of the shaft and the twisting, which occur at the location of the joint pipe connection during the reciprocal movement of the carriage, can be neutralized by the elasticity of the elastomer layer, to ensure a high level of reliability in terms of sealing performance. As for other measures, the rigidity of the valve body into which the joint pipe  180  is inserted may be rendered greater than the rigidity of the joint pipe  180 , so that the deformation of the valve body, which is caused by the run out of the shaft and the twisting, which occur at the location of the joint pipe connection during the reciprocal movement of the carriage, can be controlled, to ensure a high level of reliability in terms of sealing performance. 
     Next, referring to FIGS. 10,  17 , and  25 , the dimensions of the various components for realizing the aforementioned valve mechanism will be described. 
     Referring to FIG. 25, the dimension e 5  of the valve plug  261  in the longitudinal direction is 5.7 mm; the distance e 3  from the sealing portion  265  of the valve plug  261  to the sliding axis  261   a  of the valve plug  261 , 14.4 mm; distance e 1  from the second valve body  260   b  to the inside surface of the valve cover  262 , 8.7 mm; distance e 2  from the second valve body  260   b  to the outside surface of the valve cover  262 , 11.0 mm; length e 4  of the opening between the first valve body  260   a  and second valve body  260   b , 3.0 mm; the distance e 6  the rib-protrudes from the sealing portion  265  of the valve plug  261 , 1.3 mm; the length  12  of the valve cover welding guide  262   a , 0.8 mm; dimension b 1  of the sealing portion  265  of the valve plug  261  in the longitudinal direction, 9.7 mm; dimension b 2  of the valve plug  261 , on the valve cover side, in the longitudinal direction, 9.6 mm; dimension al of the second valve body  260   b , on the first valve body side, in the longitudinal direction; 10.2 mm; dimension a 2  of the second valve body  260   b , on the valve cover side, in the longitudinal direction, 10.4 mm; diameter c 1  of the sliding axis of the valve plug  261 , 1.8 mm; diameter c 2  of the hole of the valve cover  262 , through which the sliding axis of the valve plug  261  is put, 2.4 mm; length of a spring as the resilient member  263 , 11.8 mm (spring constant: 1.016 N/mm); R portion  262   b  of the valve cover  262 , R0.2 mm (entire circumference); length g 1  of the sealing portion  264  of the first valve body, which is a part of the elastomer layer  267 , 0.8 mm; R portion of the sealing portion  264  of the first valve body, R0.4 mm; thickness u 1  of the sealing portion  264  of the first valve body, 0.4 mm; thickness u 2  of the elastomer layer  267 , 0.8 mm; internal diameter g 2  of the elastomer layer  267  in the longitudinal direction, 8.4 mm; external diameter g 3  of first valve body  260   a  in the longitudinal direction, 10.1 mm; external diameter g 5  of the joint pipe  180  in the longitudinal direction, 8.0 mm; external diameter g 4 , inclusive of the sealing projection  180   a , of the joint pipe  180  in the longitudinal direction, 8.7 mm; distance  11  of the setback of the first valve body flange  268 , 1.0 mm; length  13  of the joint pipe  180 , 9.4 mm; and the length  14  of the valve activation projection  180   b  is 2.5 mm. 
     The length g 1  of the sealing portion  264  of the first valve body is set at 0.8 mm; it is desired that the length g 1  is sufficient to allow the sealing portion  264  of the first valve body to protrude far enough from the valve body so that the sealing portion  264  bends outward and perfectly seals the gap as it makes contact with the sealing portion  265  of the sealing portion  264  of the valve plug  261 . 
     For the reason given above, the length g 1  of the sealing portion of the first valve body has only to be within a range which satisfies the following inequality: 
     
       
         ( g   3 − g   2 )/2 &gt;g   1 &gt;( b   1  − g   2 )/2. 
       
     
     As for the dimension of the valve activation projection  180   b  of the joint pipe  180 , and the rib  311  of the valve plug  261 , which are in contact with each other as shown in FIGS. 10 and 17, the thicknesses of the joint pipe  180  and rib  211  are 0.75 mm; distance f 3  between the inside surfaces of the opposing valve activation projection  180   b , 1.7 mm; distance f 4  between the outside surfaces of the opposing valve activation projection  180   b , 3.2 mm; distance f 1  between the outside surfaces of the oblong rib  311  of the valve plug  261  at the short axis of the oblong rib  311 , 2.6 mm; distance f 2  between the inside surfaces of the rib  311  at the short axis, 1.4 mm; and the length d of the rib  311  is 3.6 mm. 
     It is desired from the viewpoint of molding accuracy that the thickness u 2  of the elastomer layer  267  on the inside surface of the first valve body  260   a  with the oblong cross section is even; the thickness at the curved portion and the thickness at the straight portion are the same. In terms of the vertical direction of the joint opening  230 , the depth of the sealing bite between the elastomer layer  267  and the largest diameter portion (portion comprising the sealing projection  180   a ) of the joint pipe  180  is: g 4 −g 2 =0.3 mm, and this amount is absorbed by the elastomer layer  267 . The total thickness of the elastomer layer  267 , which is involved in the absorption is: 0.8 mm×2 1.6 mm. However, since the depth of the bite is 0.3 mm, it does not require as much force as otherwise necessary, to deform the elastomer layer  267 . Also in terms of the horizontal direction of the joint opening  230 , the depth of the bite for sealing is set at 0.3 mm, and the elastomer layer  267 , the total thickness of which for the absorption is: 0.8 mm×2=1.6 mm, is made to absorb this amount. The exterior diameter g 5  of the joint pipe  180  in the vertical direction is smaller than the internal diameter g 2  of the elastomer layer  267 : g 5 &lt;g 2 , and this relationship also applies to the horizontal direction: g 5 &lt;g 2 . Therefore, in the state illustrated in FIG. 25, it is assured that the elastomer layer comes into contact with only the sealing projection  180   a  of the joint pipe  180 , allowing the joint pipe  180  to be smoothly inserted, to perfectly seal the joint. The play in the horizontal direction between the ink storing container  201  and holder  150  has only to be in a range (±0.8 mm in this embodiment) in which the play can be absorbed by the thickness of the elastomer layer  267 . In this embodiment, the maximum tolerance of the play is set at ±0.4 mm. In this embodiment, if the amount of the play in the horizontal direction (amount of displacement from the center) is greater than a half of the absolute value of the difference between the external diameter g 5  and the internal diameter g 2  of the elastomer layer  267  (in other words, if the amount of the play in this embodiment in terms of the horizontal direction is no less than ±0.2 mm), the external surface of the joint pipe  180 , exclusive of the external surface of the sealing portion  180   a , contacts the elastomer layer  267  across a wide range, and presses thereupon. Therefore, the resiliency of the elastomer generates centering force. 
     Employing the above listed measurements made it possible to realize a valve mechanism capable of providing the above described effects. 
     &lt;Effects of Valve Mechanism Position&gt; 
     In the case of the ink jet head cartridge in this embodiment, the valve cover  262  and second valve body  260   b  of the valve mechanism attached to the joint opening  230  of the ink container unit  200  protrude deeper into the internal bladder  220 . With this arrangement, even if the internal bladder  220  becomes separated from the external shell  210 , across the portion adjacent to the joint opening  230  due to the deformation of the internal bladder  220  caused by the consumption of the ink in the internal bladder  220 , the deformation of the internal bladder  220 , adjacent to the joint opening  230 , is regulated by the portion of the valve mechanism, which has been deeply inserted into the internal bladder  220 , that is, the valve cover  262  and second valve body  260   b . In other words, even if the internal bladder  220  deforms as the ink is consumed, the deformation of the internal bladder  220 , immediately adjacent to the valve mechanism and in the area surrounding the immediate adjacencies of the valve mechanism, is regulated by the valve mechanism, and therefore, the ink path in the adjacencies of the valve mechanism, in the internal bladder  220 , and the bubble path for allowing bubbles to rise during gas-liquid exchange, are ensured. Therefore, during the deformation of the internal bladder  220 , ink is not prevented from being supplied from the internal bladder  220  into the negative pressure controlling chamber unit  100 , and the bubbles are not prevented from rising in the internal bladder  220 . 
     In the case of the ink container unit  200  comprising the internal bladder  220  deformable as described above, or the ink jet head cartridge equipped with the negative pressure controlling chamber unit  100 , it is desired from the viewpoint of increasing the buffering space in the external shell  210  that balance is maintained between the negative pressure in the internal bladder  220  and the negative pressure in the negative pressure controlling chamber shell  110  so that the gas-liquid exchange occurs between the ink container unit  200  and negative pressure controlling chamber unit  100  after the internal bladder  220  is deformed to the maximum extent. For the sake of high speed ink delivery, the joint opening  230  of the ink container unit  200  may be enlarged. Obviously, it is desired that there is a large space in the region adjacent to the joint opening  230  of the internal bladder  220 , and that ample ink supply path is secured in this region. 
     If the deformation of the internal bladder  220  is increased to secure the buffering space in the external shell  210  which contains the internal bladder  220 , normally, the space adjacent to the joint opening  230  in the internal bladder  220  narrows as the internal bladder  220  deforms. If the space adjacent to the joint opening  230  in the internal bladder  220  narrows, the bubbles are prevented from-rising in the internal bladder  220 , and the ink supply path adjacent to the joint opening  230  is shrunk, raising the possibility that they will fail to compensate for the high speed ink delivery. Therefore, in the case that the valve mechanism does not protrude deeply into the internal bladder  220 , and the deformation of the internal bladder  220 , adjacent to the joint opening  230 , is not regulated, unlike the ink jet head cartridge in this embodiment, the amount of the deformation of the internal bladder  220  must be kept within a range in which the deformation does not substantially affect the ink delivery, so that balance is maintained between the negative pressure in the internal bladder  220  and the negative pressure in the negative pressure controlling chamber shell  110 , to compensate for the high speed ink delivery. 
     Comparatively, in this embodiment, the valve mechanism protrudes deeply into the internal bladder  220  as described above, and the deformation of the internal bladder  220 , adjacent to the joint opening  230 , is regulated by the valve mechanism. Therefore, even if the deformation of the internal bladder  220  is increased, the region adjacent to the joint opening  230 , that is, the region through which the ink supply path leads to the joint opening  230 , is secured by sufficient size, making it possible to accomplish both objects: securing a large buffering space in the external shell  210 , and securing an ink delivery path capable of accommodating high speed ink delivery. 
     Below the bottom portion of the ink container unit  200  of the above described ink jet head cartridge, an electrode  270  used as an ink remainder amount detecting means for detecting the amount of the ink remaining in the internal bladder  220 , as will be described later, is positioned. The electrode  270  is fixed to the carriage of a printer into which the holder  150  is installed. The joint opening  230  to which the valve mechanism is attached is located in the bottom portion of the ink container unit  200 , adjacent to the front wall, that is, the wall on the negative pressure controlling chamber unit side. The valve mechanism is inserted deep into the internal bladder  220  in the direction approximately parallel to the bottom surface of the ink container unit  200 , and therefore, when the internal bladder  220  deforms, the deformation of the bottom portion of the internal bladder  220  is regulated by the deeply inserted portion of the valve mechanism. In addition, the deformation of the bottom portion of the internal bladder  220  during the deformation of the internal bladder  220  is regulated also by the slanting of a part of the bottom portion of the ink storing container  201  comprising the external shell  110  and internal bladder  220 . Since the shifting of the bottom portion of the internal bladder  220  relative to the electrode  270  is regulated by the further regulation of the deformation of the bottom portion of the internal bladder  220  by the valve mechanism, in addition to, the effect of the regulation of the deformation of the bottom portion of the internal bladder  220  by the slanting of the bottom portion of the ink storing container  201 , it becomes possible to more accurately carry out the ink remainder amount detection. Therefore, the above described regulation of the deformation of the internal bladder  220 , adjacent to the joint opening  230 , by the valve mechanism makes it possible to obtain a liquid supplying system capable of more accurately detecting the ink remainder amount, in addition to accomplishing the two objectives of securing a large buffering space in the external shell  210  by increasing the deformation of the internal bladder  220 , and supplying ink at a high rate. 
     In this embodiment, the valve mechanism is inserted deeper into the internal bladder  220  so that the deformation of the internal bladder  220 , adjacent to the joint opening  230 , is regulated as described above, but a member different from the valve mechanism may be inserted into the internal bladder  220  to regulate the deformation of the aforementioned portion of the internal bladder  220 . Further, a piece of plate may be inserted into the internal bladder  220  through the joint opening  230  so that the piece of plate stretches along the bottom surface of the internal bladder  220 . With this arrangement, more accurate ink remainder amount detection can be carried out when the ink remainder amount in the internal bladder  220  is detected with the use of the electrode  270 . 
     In addition, in this embodiment, in the valve mechanism attached to the joint opening  230 , the structural components of the valve mechanism protrude far deeper into the internal bladder  220 , beyond the opening  260   c  which is connected to the joint opening  230  to form an ink path. With this structural arrangement, it is assured that an ink path is secured in the adjacencies of the joint opening  230 , in the internal bladder  220  of the ink container unit  200 . 
     &lt;Production Method for Ink Container&gt; 
     Next, referring to. FIG. 18, a production method for the ink container in this embodiment will be described. First, referring to FIG. 18, ( a ), the exposed portion  221   a  of the internal bladder  220  of the ink storing container  201  is directed upward, and the ink  401  is injected into the ink storing container  201  with the use of an ink injection nozzle  402  through the ink delivery opening. In the case of the structure in accordance with the present invention, ink injection can be performed under the atmospheric pressure. 
     Next, referring to FIG. 18, ( b ), the valve plug  261 , valve cover  262 , resilient member  263 , first valve body  260   a , and second valve body  260   b , are assembled together into a valve unit, and then, this valve unit is dropped into the ink delivery opening of the ink storing container  201 . 
     At this point in time, the periphery of the sealing surface  102  of the ink storing container  201  is surrounded by the stepped shape of the first valve body  260   a , on the outward side of the welding surface, making it possible to improve the positional accuracy with which the ink storing container  201  and first valve body  260   a  are positioned relative to each other. Thus, it becomes possible to lower a welding horn  400  from above to be placed in contact with the periphery of the joint opening  230  of the first valve body  260   a , so that the first valve body  260   a  and the internal bladder  220  of the ink storing container  201  are welded to each other at the sealing surface  102 , and at the same time, the first valve body  260   a  and the external shell  210  of the ink storing container  201  are welded to each other at the periphery of the sealing surface  102 , assuring that the joints are perfectly sealed. The present invention is applicable to a production method which uses ultrasonic welding or vibration welding, as well as a production method which uses thermal welding, adhesive, or the like. 
     Next, referring to FIG. 18, ( c ), the ID member  250  is placed on the ink storing container  201  to which the first valve body  260   a  has been welded, in a manner to cover the ink storing container  201 . During this process, the engagement portions  210   a  formed in the side wall of the external shell of the ink storing container  201 , and the click portions  250   a  of the ID member  250 , engage, and at the same time, the click portions  250   a  located on the bottom surface side engage, with the external shell  210 , on the side opposite to the sealing surface  102  of the ink storing container  201 , with the first valve body  260   a  interposed (FIG.  3 ). 
     &lt;Detection of Ink Remainder Amount in Container&gt; 
     Next, the detection of the ink remainder amount in the ink container unit will be described. 
     Referring to FIG. 2, below the region of the holder  150  where the ink container unit  200  is installed, the electrode  270  in the form of a piece of plate with a width narrower than the width of the ink storing container  201  (depth direction of the drawing) is provided. This electrode  270  is fixed to the carriage (unillustrated) of the printer, to which the holder  150  is attached, and is connected to the electrical control system of the printer through the wiring  271 . 
     On the other hand, the ink jet head unit  160  comprises: an ink path  162  connected to the ink delivery tube  165 ; a plurality of nozzles (unillustrated) equipped with an energy generating element (unillustrated) for generating the ink ejection energy; and a common liquid chamber  164  for temporarily holding the ink supplied through the ink path  162 , and then, supplying the ink to each nozzle. Each energy generating element is connected to a connection terminal  281  with which the holder  150  is provided, and as the holder  150  is mounted on the carriage, the connection terminal  281  is connected to the electrical control system of the printer. The recording signals from the printer are sent to the energy generating elements through the connection terminal  281 , to give ejection energy to the ink in the nozzles by driving the energy generating elements. As a result, ink is ejected from the ejection orifices, or the opening ends of the nozzles. 
     Also, in the common liquid chamber  164 , an electrode  290  is disposed, which is connected to the electrical control system of the printer through the same connection terminal  281 . These two electrodes  270  and  290  constitute the ink remainder amount detecting means in the ink storing container  201 . 
     Further, in this embodiment, in order to enable this ink remainder amount detecting means to detect more accurately the ink remainder amount, the joint opening  230  of the ink container unit  200  is located in the bottom portion, that is, the bottom portion when in use, in the wall of the ink storing container  201 , between the largest walls of the ink storing container  201 . Further, a part of the bottom wall of the ink supplying container  201  is slanted so that the bottom surface holds an angle relative to the horizontal plane when the ink storing container  201  is in use. More specifically, referring to the side, where the joint opening  230  of the ink container unit  200  is located, the front side, and the side opposite thereto, the rear side, in the adjacencies of the front portion in which the valve mechanism is disposed, the bottom wall is rendered parallel to the horizontal plane, whereas in the region therefrom to the rear end, the bottom wall is slanted upward toward the rear. In consideration of the deformation of the internal bladder  220 , which will be described later, it is desired that this angle at which the bottom wall of the ink storing container  201  is obtuse relative to the rear sidewall of the ink container unit  200 . In this embodiment, it is set to be no less than 95 degrees. 
     The electrode  270  is given a shape which conforms to the shape of the bottom wall of the ink storing container  201 , and is positioned in the area correspondent to the slanted portion of the bottom wall of the ink storing container  201 , in parallel to the slanted portion. 
     Hereinafter, the detection of the ink remainder amount in the ink storing container  201  by this ink remainder amount detecting means will be described. 
     The ink remainder amount detection is carried out by detecting the capacitance (electrostatic capacity) which changes in response to the size of the portion of the electrode  270  correspondent to where the body of the remaining ink is, while applying pulse voltage between the electrode  270  on the holder  150  side and the electrode  290  in the common liquid chamber  164 . For example, the presence or absence of ink in the ink storing container  201  can be detected by applying between the electrodes  270  and  290 , such pulse voltage that has a peak value of 5V, a rectangular wave-form, and a pulse frequency of 1 kHz, and computing the time constant and gain of the circuit. 
     As the amount of the ink remaining in the ink storing container  201  reduces due to ink consumption, the ink liquid surface descends toward the bottom wall of the ink storing container  201 . As the ink remainder amount further reduces, the ink liquid surface descends to a level correspondent to the slanted portion of the bottom wall of the ink storing container  201 . Thereafter, as the ink is further consumed (the distance between the electrode  270  and the body of the ink remains approximately constant), the size of the portion of the electrode  270  correspondent to where the body of ink remains, gradually reduces, and therefore, capacitance begins to reduce. 
     Eventually, the ink will disappear from the area which corresponds with the position of the electrode  270 . Thus, the decrease of the gain, and the increase in electrical resistance caused by the ink, can be detected by computing the time constant by changing the pulse width of the applied pulse or changing the pulse frequency. With this, it is determined that the amount of the ink in the ink storing container  201  is extremely small. 
     The above is the general concept of the ink remainder amount detection. In reality, in this embodiment, the ink storing container  201  comprises the internal bladder  220  and external shell  210 , and as the ink is consumed, the internal bladder  220  deforms inward, that is, in the direction to reduce its internal volume, while allowing gas-liquid exchange between the negative pressure controlling chamber shell  110  and ink storing container  201 , and the introduction of air between the external shell  210  and internal bladder  220  through the air vent  222 , so that balance is maintained between the negative pressure in the negative pressure controlling chamber shell  110  and the negative pressure in the ink storing container  201 . 
     Referring to FIG. 6, during this deformation, the internal bladder  220  deforms while being controlled by the corner portions of the ink storing container  201 . The amount of the deformation of the internal bladder  220 , and resultant partial or complete separation of the walls of the internal bladder  220  from the external shell  210 , are the largest at the two walls having the largest size (walls approximately parallel to the plane of the cross sectional in FIG.  6 ), and is small at the bottom wall, or the wall adjacent to the above two walls. Nevertheless, with the increase in the deformation of the internal bladder  220 , the distance between the body of the ink and the electrode  270 , and the capacitance decreases in reverse proportion to the distance. However, in this embodiment, the main area of the electrode  270  is in a plane approximately perpendicular to the deformational direction of the internal bladder  220 , and therefore, even when the internal bladder  220  deforms, the electrode  270  and the wall of the bottom portion of the internal bladder  220  remain approximately parallel to each other. As a result, the surface area directly related to the electrostatic capacity is secured in terms of size, assuring accuracy in detection. 
     Further, as described before, in this embodiment, the ink storing container  201  is structured so that the angle of the corner portion between the bottom wall and the rear sidewall becomes no less than  95  degrees. Therefore, it is easier for the internal bladder  220  to separate from the external shell  210  at this corner compared to the other corners. Thus, even when the internal bladder  220  deforms toward the joint opening  230 , it is easier for the ink to be discharged toward the joint opening  230 . 
     Hereinbefore, the structural aspects of this embodiment were individually described. These structures may be employed in optional combinations, and the combinations promise a possibility of enhancing the aforementioned effects. 
     For example, combining the oblong structure of the joint portion with the above described valve structure stabilizes the sliding action during the installation or removal, assuring that the value is smoothly open or closed. Giving the joint portion the oblong cross section assures an increase in the rate at which ink is supplied. In this case, the location of the fulcrum shifts upward, but slanting the bottom wall of the ink container upward makes possible stable installation and removal, that is, the installation and removal during which the amount of twisting is small. 
     &lt;Ink Jet Head Cartridge&gt; 
     FIG. 23 is a perspective view of an ink jet head cartridge employing an ink container unit to which the present invention is applicable, and depicts the general structure of the ink jet head cartridge. 
     An ink jet head cartridge  70  in this embodiment, illustrated in FIG. 23, is provided with the negative pressure controlling chamber unit  100 , which comprises the ink jet head unit  160  enabled to eject plural kinds of ink different in color (yellow (Y), magenta (M), and cyan (C), in this embodiment) and the negative pressure controlling chamber unit  100  integrally comprising the negative pressure controlling chamber shells  110   a ,  110   b , and  110   c . The ink container units  200   a ,  200   b , and  200   c , which contain liquid different in color are individually and removably connectible to the negative pressure controlling chamber unit  100 . 
     In order to assure that the plurality of the ink container units  200   a ,  200   b , and  200   c , are connected to the correspondent negative pressure controlling chamber shells  110   a ,  110   b , and  110   c , without an error, the ink jet head cartridge is provided with the ink holder  150 , which partially covers the exterior surface of the ink container unit  200 , and each ink container unit  200  is provided with the ID member  250 . The ID member  250  is provided with the plurality of the recessed portions, or the slots, and is attached to the front surface of the ink container unit  200 , in terms of the installation direction, whereas the negative pressure controlling chamber shell  110  is provided with the plurality of the ID members  170  in the form of a projection, which corresponds to the slot in position and shape. Therefore, it is assured that the installation error is prevented. 
     In the case of the present invention, the color of the liquid stored in the ink container units may be different from Y, M, and C, which is obvious. It is also obvious that the number of the liquid containers and the type of combination of the liquid containers (for example, a combination of a single black (Bk) ink container and a compound ink container containing inks of Y, M, and C colors), are optional. 
     &lt;Recording Apparatus&gt; 
     Next, referring to FIG. 24, an example of an ink jet recording apparatus in which the above described ink container unit or ink jet head cartridge can be mounted will be described. 
     The recording apparatus shown in FIG. 24 is provided with: a carriage  81  on which the ink container unit  200  and the ink jet head cartridge  70  are removably installable; a head recovery unit  82  assembled from a head cap for preventing ink from losing liquid components through the plurality of orifices of the head and a,suction pump for sucking out ink from the plurality of orifices as the head malfunctions; and a sheet feeding surface  83  by which recording paper as recording medium is conveyed. 
     The carriage  81  uses a position above the recovery unit  82  as its home position, and is scanned in the leftward direction as a belt  84  is driven by a motor or the like. Printing is performed by ejecting ink from the head toward the recording paper conveyed onto the sheet feeding surface  83 . 
     As described above, the above structure in this embodiment is a structure not found among the conventional recording apparatuses. Not only do the aforementioned substructures of this structure individually contribute to the effectiveness and efficiency, but also contribute cooperatively, rendering the entirety of the structure organic. In other words, the above described substructures are excellent inventions, whether they are viewed individually or in combination; disclosed above are examples of the preferable structure in accordance with the present invention. Further, although the valve mechanism in accordance with the present invention is most suitable for the usage in the above described liquid container, the configuration of the liquid container does not need to be limited to the above described one; it can be also applied to liquid containers of different types in which liquid is directly stored in the liquid delivery opening portion. 
     Next, the description of the ink container in accordance with the present invention will be supplemented, while describing the modified versions of the above described almost immovably fixing structure, which characterizes the present invention, for joining an ink container, an ink storing container, and an ID member, with reference to the appended drawings. 
     &lt;Modification  1 &gt; 
     FIG. 26 is a drawing for showing the first modification of the structure, in accordance with the present invention, for almost immovably fixing the ink storing container of an ink container, and an ID member, to each other. 
     Referring to FIG. 26, ( a ), in the case of the ink container in this modified version of the above described embodiment (hereinafter, “modified version” or “modification”), the front wall of the ink container  201  is provided with an engagement portion  550  in the form of an arrowhead, and the ID member  250  is provided with an engagement slit  551 , that is, an indentation also in the form of an arrowhead. The arrowhead-like engagement portion  550  may be located at either the top portion or side portion of the ink storing container  201  as long as it is on the front wall of the ink storing container  201 . The arrowhead-like engagement portion is pointed in the ink container installation direction. 
     Referring to FIG. 26, ( b ), in the case of the ink container in this modified version, which is structured as described above, as the ID member  250  is attached to the ink storing container  201 , the arrowhead-like engagement portion  550  fits into the engagement slit  551 . Thus, the shoulder portion of the arrowhead-like engagement portion  550  engages with the engagement slit  551 , almost immovably fixing the ID member  250  and the ink storing container  201  to each other. 
     According to this embodiment, the arrowheadlike engagement portion  550  is pointed in the ink container installation direction, indicating the direction in which the ink container is to be installed. Further, the arrowhead-like engagement portion  550  is inserted while expanding the gap of the engagement slit  551  by its tapered portion. Therefore, the amount of the force necessary to insert the arrowhead-like engagement portion  550  into the arrowhead-like slit  551  may be small, making it possible to almost immovably fix the ID member  250  to the ink storing container  201 . In addition, at the final moment the tapered portion of the arrowhead-like engagement portion  550  completely fits into the engagement slit  551 , a feel of click is provided, assuring that the ID member  250  is perfectly fixed to the ink storing container  201  in the almost immovable manner. 
     &lt;Modification  2 &gt; 
     FIG. 27 is a drawing for showing the second example of the modification of the structure, in accordance with the present invention, for almost immovably fixing the ink storing container and the ID member to each other. 
     Referring to FIGS. 27, ( a ) and ( b ), in the case of the ink container in this example of the modification, an engagement shaft  552  is provided on the front surface of the ink storing container  201 , and the top wall of the ID member  250  is provided with an engagement hole  553  into which the engagement shaft  552  is inserted. The engagement shaft  552  is formed in an undercut shape, or a shape in which the top portion is bigger than the base portion. In addition, referring to FIG. 27, ( c ), the front surface of the ink storing container  201  is provided with a pair of engagement rail grooves  554 , which extend along the lateral edges, and the ID member  250  is provided with a pair of engagement rails  555 , which are on the inward surface of the ID member  250 , extending along the lateral edges, and engage with the engagement rail grooves  554 . The structural arrangement may be such that the engagement rails  555  are provided on the ink storing container side, and the engagement rail grooves  554  are provided on the ID member side. 
     FIG. 28 is a perspective view which shows the assembly process for the ink container illustrated in FIG.  27 . 
     When almost immovably fixing the ID member  250  to the ink storing container  201 , first, the ID member  250  is positioned above the ink storing container  201 , so that the engagement rail grooves  554  of the ink storing container  201  align with the engagement rails  555  of the ID member  250 . Next, the ID member  250  is slid along the engagement rail groove  554  in a manner to push the engagement shaft  552  into the engagement hole  553 . As a result, the ID member  250  is almost immovably fixed to the ink storing container  201 . 
     According to this modification, the engagement rail grooves  554  and engagement rails  555  function as the guides for accurately positioning both of the components  201  and  250  relative to each other, making it easier to position them, and therefore, reducing the assembly time for the ink container. In addition, at the last moment the large diameter portion of the engagement shaft  552  perfectly fits into the engagement hole  553 , clicking is felt, assuring that the ID member  250  and ink storing container  201  are almost immovably fixed to each other. 
     &lt;Other Examples of Modification&gt; 
     In addition to the above described example of the modification of the structure, in accordance with the present invention, for almost immovably fixing the ID member and ink storing container to each other, the following examples may be listed. FIGS. 29 and 30 show these structures for almost immovable fixation. 
     Referring to FIG. 29, in this modification of the structure for almost immovably fixing the ID member  250  and ink storing container  201  to each other, the ink storing container  201  is provided with an engagement projection  510 , which is positioned on the ID member side so that its axial line and the axial line of the first valve body  260   a  are positioned in the same plane. The ID member  250  is provided with engagement indentation  511  which corresponds to the engagement projection  510 . Both engagement portions  510  and  511  are given an undercut shape, and the ID member  250  and ink storing container  201  are almost immovably fixed to each other as the engagement projection  510  is fitted into the engagement indentation  511 . In this modification, the pinch-off portion  512  of the ink storing container  201 , which results from blow molding, is utilized to form the engagement projection  510 , making it easier to form the structure for the fixation. 
     In another modification illustrated in FIG. 30, the ink storing container  201  is provided with a resilient detent  513 , which is formed by utilizing the pinch-off portion  512 , which results from blow molding, whereas the ID member  250  is provided with a rib hole  514  in which the detent  513  is engageable. In the modification illustrated in FIG. 30, the ID member  250  and ink storing container  201  are almost immovably fixed to each other as the detent  513  engages into the rib hole  514 . 
     Next, the description of the ink container in accordance with the present invention will be supplemented while describing the further modifications of the present invention, to which the above described various modifications are applicable, in comparison to the embodiment illustrated in FIG.  2 . 
     The modification illustrated in FIG. 31 is different from the embodiment illustrated in FIG. 2, in that the structure of the ink container unit illustrated in FIG. 31 is such that the ID member  250  and valve body  260   a  have been formed as two integral portions of a single component. 
     FIG. 32 is a perspective drawing for describing the ink container unit  200  illustrated in FIG. 31, wherein FIG. 32, ( a ), is a perspective view of the ink container unit  200  in the assembled state, and the FIG. 31, ( b ), is a perspective view of the ink container unit  200  in the disassembled state. 
     In this modification, the ID member  250  is provided with the above described first valve body  260   a , which is formed as an integral part of the ID member  250 . This valve body  260   a  is used as a part of the structure of the valve mechanism for controlling the ink flow in the joint opening  230 . This valve mechanism opens or closes by being placed in contact with the joint pipe  180  of the negative pressure controlling chamber unit  100 . 
     In this modification, the ID member  250  is joined with both the external shell  210  and internal bladder  220  of the ink storing container  201 . More specifically, the ID member  250  is welded to the internal bladder  220  by welding between the sealing surface  102  of the internal bladder  220 , which coincides with the portion where the ink is drawn out of the ink storing container  201 , and the area of the surface of the ID member  250 , which corresponds to joint opening  230  portion. Since the external shell  210  is formed of polypropylene as is the innermost layer of the internal bladder  220 , the ID member  250  and internal bladder  220  can be welded to each other around the joint opening  230 . 
     With the above welding, the ink storing container  201  is completely sealed around the ink delivery opening portion, preventing the ink leakage or the like from the seam portion between the ID member  250  and ink storing container  201  which otherwise occurs. When welding is used as means for joining, as in the case of the ink container unit  200  in this embodiment, it is desired in order to improve sealing performance that the material for the layer of the internal bladder  220 , which provides the internal bladder  220  with the joining surface, and the material for the ID member  250 , are the same. 
     As for the joining of the external shell  210  and ID member  250  to each other, the engagement portion  210   a  provided in the upwardly facing surface of the external shell  210 , is engaged with the click (unillustrated) provided in the top portion of the ID member  250 , and the engagement portions  210   b  and  210   c  provided in the laterally facing surfaces of the external shell  210  are engaged with the click portions  210   b  and  210   c  on the ID member  250  side, which almost immovably fixes the ID member  250  to the ex 210 . The phrase almost immovably fixing means fixing with the use of a desirable structural arrangement characterized in that it comprises a combination of a projection and a recess, or the like, which can be easily engaged or interlocked, and also can be easily disengaged. By almost immovably fixing the ID member  250  to the ink storing container  201  as described above, the shock generated by the contact between the ID member  170  and ID member slots  252  during the installation or removal can be absorbed, preventing the occurrences of damage to the ink container unit  200  and negative pressure controlling chamber unit  100 . 
     Further, by partially and yet almost immovably fixing the ID member  250  to the ink storing container  201  as described above, it becomes easier to disassemble the ink container unit  200 , improving efficiency in recycling. Forming the engagement indentation as the engagement portion  210   a  in the upward facing wall of the external shell  210  as described above makes it possible to simplify the structure of the ink storing container  201 , for its production with the use of blow molding, which in turn makes it easier to simplify the molds, and also to control the film thickness. 
     In addition, when joining the external shell  210  and ID member  250  to each other, it is desired that the points at which the ID member  250  is welded to the external shell  210  to fix the ID member  250  to the external shell  210 , includes the position adjacent to the top portion of the joint opening  230 . This arrangement assures that the ID member  250  is fixed so that the center of the ID member  250  vertically lines up with the axial line of the joint opening  230  (major axis of the joint opening  230 ). Therefore, it is possible to increase the integrity of the ink container unit  200  against the force generated in the aforementioned axial direction during the installation. Further, since a small amount of rotational movement is allowed, it is possible to stabilize the installation of the ink container unit  200 . 
     Further, regarding the ink storing container  201 , the portion covered by the ID member  250  is recessed, and the ink delivery portion projects. Therefore, the projecting portions on the front surface of the ink container unit  200  can be covered by fixing the ID member  250  to the ink storing container  201 . The relationship between the engagement portions  210   a  of the external shell  210  and the click portions  250   a  of the ID member  250  in terms which is projecting and which is recessed may be reversal. It is desired that the points at which the ID member  250  is almost immovably fixed to the ink container unit  200  are located in a manner to encircle the sealing surface  102  of the internal bladder  220 . This placement renders the seam between the ID member  250  and the ink container unit  200  strong enough to withstand the force which applies to the ID member  250  during the installation or removal of the ink container unit  200 . Also, the positions of the ink storing container  201  and ID member  250  can be regulated in terms of both the vertical and horizontal directions. The method for joining the ink storing container  201  and ID member  250  to each other does not need to be limited to those methods presented in the above description of the embodiments; other methods may be used. 
     Next, referring to FIG. 33, a method for manufacturing the ink containers in this modification will be described. 
     First, referring to FIG. 33, ( a ), the exposed portion  221   a  of the internal bladder  220  of the ink storing container  201  is directed upward, and the ink  501  is injected into the ink storing container  201  with the use of an ink injection nozzle  502 . In the case of the structure in accordance with the present invention, ink injection can be performed under the atmospheric pressure. 
     Next, referring to FIG. 33, ( b ), the ID member  250  into which the valve plug  261 , valve cover  262 , and resilient member  263 , has been assembled, is placed in a manner to cover the ink storing container  201 . During this process, the engagement portions  210   a  with which the external shell of the ink storing container  201  is provided are engaged with the click portions  250   a  of the ID member  250 , accurately fixing the positional relationship between the ink storing container  201  and the ID member  250 . 
     After the above described almost immovable fixing, the above described welding encircling the joint opening is carried out. By almost immovably fixing the ID member  250 , the joining of the ID member  250  becomes easy, and it becomes possible to simply increase the positional accuracy. Referring to FIG. 33, ( c ), the welding horn  500  is placed from above, in contact with, the periphery of the joint opening  230  of the ID member  250 , so that the ID member  250  and the internal bladder  220  are welded to each other at the sealing surface  102 . The present invention is applicable to a production method which uses ultrasonic welding or vibration welding, as well as a production method which uses thermal welding, adhesive, or the like. 
     As described above, according to the present invention, the ink container comprises a liquid storing portion for storing liquid, and an identification member for identifying the liquid in the liquid storing portion. Therefore, when manufacturing ink containers for inks of different color, cost can be reduced by manufacturing the liquid storing portions as common components. Separating the ink container into two subsections, that is, the identification member and the liquid storing portion, makes it possible to form the liquid storing portion, namely, a container with multilayer wall, with the use of multilayer blow molding, and the identification member, which requires a higher degree of dimensional accuracy, with the use of injection molding. Therefore, it is possible to provide an ink container which guarantees more stable ink delivery, and more accurate identification, compared to a container which is provided with the identification function, and is formed as a single piece component. 
     Further, the identification portion and ink delivery opening are formed as different portions of the single piece identification member, and therefore, the accuracy in the positional relationship between the identification portion and ink delivery portion is improved. Therefore, it is possible to prevent the container from being incorrectly installed due to the interference from the identification portion, which occurs when connecting the ink delivery opening to the recording head on the holder side during the installation of the container into the holder. 
     Further, joining the identification member to the internal bladder of the liquid storing portion, in particular, joining the ink delivery opening of the identification member with the internal bladder, encircling the ink delivery opening of the liquid storing portion, makes it possible to prevent ink from leaking from the ink delivery opening of the ink container which is repeatedly installed or removed. In this case, if the same material is chosen as the material for both the liquid storing portion and identification member, sealing performance is further improved. 
     Further, the external force which applies to the identification member is absorbed by almost immovably fixing the identification member to the liquid storing portion, except for the region around the ink delivery opening. Therefore, the occurrence of damage to the ink container can be prevented. Partially and almost immovably fixing as described above is desirable in terms of ease of disassembly, and effective in terms of recycling. Further, the identification member is fixed to the liquid storing portion, also at the top portion of the wall having the ink delivery opening, increasing the level of the solidity with which the identification member is attached to the liquid storing portion in terms of the axial direction of the ink delivery opening. Therefore, it is possible to improve the ink container in terms of its integrity against the force generated in the aforementioned axial direction during the installation of the ink container. 
     FIG. 34 shows another modification, according to which the ink storing container  503  as the liquid storing container does not have a laminar structure inclusive of the inner bladder. Instead, the ink storing container  503  in this modification is a simple container with a monolayer wall. As a variation of this modification, the ink storing container  201  of the ink container illustrated in FIG. 2 may be replaced with a simple container with a monolayer wall as shown in FIG.  35 . 
     In particular, in the modification illustrated in FIG. 35, the valve unit is protected by the identification member, and the identification member is attached, with the use of an easily reversible joining method. Therefore, the process in which the valve unit is positioned relative to the liquid storing portion, and is fixed to the liquid storing portion, can be carried out independently from the identification member. As a result, it is possible to improve the accuracy in the positional relationship of the valve unit relative to the liquid storing portion, which in turn improves the sealing performance of the welding seam between the liquid storing portion and valve unit. 
     Studying the ink container in the above described modification from the viewpoint regarding the valve unit, it can be said that the identification member is functioning as the protection cover which covers the joint between the valve unit and liquid storing portion. Since the open end  1000  of the valve unit protrudes from the flange  268 , and the identification member fits around the valve unit, the occurrence of the liquid leakage caused by the structure of the contact between the protective cover and the unit for supporting the valve mechanism is prevented, and also it is assured that the unit is protected. As far as the present invention is concerned, the selection of the unit does not need to be limited to those in the preceding embodiments; any of the publicly known units or various other units suffices as long as it comprises a valve mechanism which can be opened or closed. Further, the provision of the flange further assures the joining of the container and unit, and also that the exterior surface of the protective cover is approximately evenly aligned with the end of the liquid path. Therefore, the overall contour of the container becomes smooth, and also the liquid leakage is prevented. 
     As for examples of the easily reversible means for joining the ink container illustrated in FIGS. 34 and 35, various methods illustrated in FIGS. 26-30 may be employed, in addition to the click combination of the projection ( 250   a ) illustrated in FIGS. 3 and 32, and the engagement portion ( 210   a  in FIG. 3, and  210   a ,  210   b , and  210   c , in FIG.  32 ). 
     FIGS. 36 and 37 show another modification of the present invention. This modification is characterized in that a seal for showing the type of the liquid stored in a container, or the like, is adhered in a manner to cover both the ID member  250  and ink storing container  201 , functioning as a supplementary engagement portion when assembling the ink container by uniting the two components. Further, referring to FIG. 37, in this modification, in order to make it easier to form the click portions  250   b  which engage with the flange of the valve unit which has the joint opening  230 , the ID member is provided with an opening  1010 , which is located in the wall having the joint opening  230 . To supplement the description, referring to FIG. 36, ( b ), which is the perspective view of the disassembled ink container unit, although the ID member is highly precisely formed by injection molding or the like, the click portions  250   a  of the ID member, which are arranged in an opposing manner, are formed along the long edges of the opening, which faces the ink container. Therefore, it is easy to force the ID member out of its mold, within the range of the elastic deformation of the ID member. On the other hand, unlike the click portions  250   a , the click portions  250   b  of the ID member, which are formed along the long edges of the opening which faces the ink container, are difficult to force out of the mold. Therefore, the opening  1010  is provided, and the click  250   b  can be easily formed by pulling the mold out of this hole. 
     In this modification, the ID member  250  and ink storing container  201  are joined to each other, by the provision of the engagement portion  210   a  and click portions  250   a , on the opposing pair of the largest flat walls (walls which constitute the sidewalls when the attitude for usage is assumed) of the ink container unit, away from the joint opening. On the side of the wall which constitutes the bottom wall when positioned for use, they are joined by the flange portion of the valve unit with the joint opening  230 , and the click portions  250   b  which engage with this flange portion. Since the easily disengageable engagement portion is located in the portion which constitutes the bottom wall when positioned for use, it is possible to prevent the ID member  250  from becoming disengaged from the ink storing container  201  when the ink container unit is removed from the ink jet head cartridge, even after the ink container unit has been installed into, or removed from, the ink jet head cartridge numerous times. Further, since the engagement portion  210   a  and click portions  250   a  are located on the flat surfaces of the ink container unit which constitute the lateral surfaces when the attitude for use is assumed, away from the joint opening portion, it is possible to prevent the ID member  250  from becoming disengaged from the ink storing container  201 , even if force is applied in the direction perpendicular to these lateral wall surfaces during the aforementioned installation or removal. In addition, since the engagement portions  210   a  and click portions  250   a  are located away from the joint opening portion, it is possible to prevent the ID member  250  from becoming disengaged from the ink storing container  201  when the ink container unit is installed into the ink jet head cartridge. Further, since the seal is adhered to the ink container unit in a manner to cover both the ID member  250  and ink storing container  201 , across the areas which constitute the top areas when the attitude for use is assumed by the ink jet head cartridge, it is possible to more effectively prevent the ID member  250  from becoming disengaged from the ink storing container  201  when the ink container unit is installed into the ink jet head cartridge. 
     While the invention has been described with reference to the structures disclosed herein, it is not confined to the details set forth, and this application is intended to cover such modifications or changes as may come within the purposes of the improvements or the scope of the following claims.