Abstract:
A liquid supplying system using a negative pressure producing member accommodating chamber including a liquid supply portion for supplying liquid to outside, an air vent for fluid communication with ambience and a negative pressure producing member accommodating chamber for accommodating a negative pressure producing member for retaining the liquid therein, and using a liquid accommodating container which is detachably mountable to said negative pressure producing member accommodating chamber and which defines a substantially hermetically sealed space except for fluid communication with said negative pressure producing member accommodating chamber, the improvement residing in: an air introducing groove, provided at a connecting portion relative to said negative pressure producing member accommodating container in said liquid accommodating container, for gas-liquid exchange for permitting introduction of the gas into the liquid containing portion and discharge of the liquid.

Description:
FIELD OF THE INVENTION AND RELATED ART 
     The present invention relates to a liquid delivery system which uses negative pressure to deliver liquid out of a liquid container, more specifically, a liquid delivery system for delivering liquid to a liquid jet recording apparatus which records images on recording medium. It also relates to a replaceable liquid container for the liquid delivery system, and a head cartridge. 
     There are a number of liquid delivery methods which use negative pressure to deliver liquid out of a liquid container. In the field of an ink jet recording apparatus, for example, an ink container which provides an ink jet recording head with negative pressure has been proposed, and has been put to practical use, in the form of an ink jet cartridge which integrally comprises a recording head and a negative pressure providing ink container. There are a number of ink jet cartridges, which can be classified into two groups: those which cannot be separated into a recording head and an ink container (ink storing portion), and those which can be separated into a recording means and an ink storing portion. In the case of the latter group, they can be individually separated from a recording apparatus, but remain united when they are used for recording. 
     There are various methods for generating negative pressure in the aforementioned liquid delivery system, and the simplest one is to use the capillary force of porous material. An ink container used for such a method comprises a shell, and a piece of porous material such as sponge for storing ink. The shell is provided with an air vent through which the atmospheric air is taken into the ink storing portion of the ink container so that ink is smoothly delivered during a printing operation. It is preferable that the porous material is compressed into the shell to fill virtually the entirety of the internal space of the ink container. 
     However, the usage of porous material as ink holding material creates some problems. One such problem is that the filling of an ink container with porous material reduces the ratio of the amount of ink storable in an ink container to the internal space of the ink container. In order to solve this problem, the applicants of the present invention proposed an ink container, which is disclosed in EP0580433 (official gazette). According to this proposal, an ink container is provided with a virtually sealed ink reservoir, and a negative pressure holding chamber in which a negative pressure generating member is held. The internal spaces of the ink reservoir and negative pressure generating member holding chamber are connected through a passage, and the negative pressure generating member holding chamber is open to the atmosphere. The applicants of the present invention also disclosed another invention disclosed in EP081531 (official gazette). According to this invention, an ink reservoir is made replaceable. 
     In the case of the aforementioned ink container, the ink within the ink reservoir is delivered from the ink reservoir to the negative pressure generating member holding chamber, as the atmospheric air displaces the ink within the ink reservoir in response to the ink delivery from the ink reservoir. Thus, the aforementioned ink reservoir has merit in that the negative pressure is kept virtually constant while the ink is delivered during this gas-liquid exchange stage. 
     The applicants of the present invention also proposed a liquid storing container, which is disclosed in EP0738605 (official gazette). According to this proposal, a liquid storing container comprises an outer shell in the form of a virtually polygonal prism, and a liquid storing portion placed in the outer shell. This proposal is characterized in that the liquid storing portion is similar in shape to the outer shell, the outward surface of each of its walls being in contact with, or closely following, the inward surface of the correspondent wall of the outer shell; that the liquid storing portion is enabled to deform in response to the outward delivery of the liquid stored in the liquid storing portion; and that the thickness of the walls of the liquid storing portion is greater at its corner portions than at the center portions of the walls. The liquid storing portion of this liquid storing container contracts by a proper amount in response to the ink delivery therefrom (liquid in the ink storing portion is not displaced by gas), so that liquid can be delivered while maintaining a proper amount of negative pressure. Therefore, unlike a conventional ink storing member, which is in the form of a pouch, this liquid storing container does not have any restriction regarding its positioning. Thus, it can be mounted on a carriage. Further, ink is directly stored in the storing portion, which makes this invention superior also in terms of ink storage efficiency. 
     It should be noted here that, in the case of an ink container of such a type that comprises a negative pressure generating member holding chamber such as the one described above, and a matching ink reservoir which is placed adjacent to the negative pressure generating member holding chamber, and is provided with a predetermined amount of storage space, gas is introduced into the ink reservoir to displace the ink (gas-liquid exchange occurs) as the ink within the ink reservoir is delivered into the negative pressure generating member holding chamber. 
     In other words, as the ink in the ink reservoir is delivered to the negative pressure generating member holding chamber, the atmospheric air is introduced into the ink reservoir in response to the ink delivery, by an amount equal to the amount of the delivered ink. Therefore, the ink reservoir is occupied with both the introduced outside air, and ink. If the air in the ink reservoir is expanded by the changes (for example, daily temperature fluctuation) in the ambience in which the printer is used, the ink within the ink reservoir is sometimes forced into the negative pressure generating member holding chamber side by the expansion. For this reason, in the past, the ratio of the amount by which the ink is moved, to the air expansion, in various environments in which the recording apparatus is used, had to be taken into consideration to provide the negative pressure generating member with the maximum amount of buffering space, in terms of practical use. As a result, it was very difficult to provide an ink reservoir with an internal volume greater than a certain size. 
     In order to solve the above described problems, the inventors of the present invention analyzed in detail an ink container of such a type that comprised a negative pressure generating member holding chamber, and an ink reservoir matching the negative pressure generating member holding chamber, in the state in which the ink reservoir contained air. As a result, it was discovered that the delivery of the ink in the ink reservoir to the negative pressure generating member holding chamber is directly linked to the introduction of the outside air, and therefore, in order to solve the above described problem, the amount by which ink moves from the ink reservoir to the negative pressure generating member should be regulated. 
     Further analysis led the inventors to an idea that, although it is impossible to prevent the air present in the ink reservoir from expanding, it is possible to contain the effect of the expansion of the air in the ink reservoir, within the ink reservoir, which is contrary to the conventional concept. 
     SUMMARY OF THE INVENTION 
     The present invention was made as the result of further study of the aforementioned discovery and knowledge carried out by the inventors of the present invention. 
     An essential thought kept in the minds of the inventors of the present invention was in order to reliably deliver ink even immediately after the exchange of the ink reservoir, a structure for enhancing the introduction of atmospheric air, which effectively functions without being clogged by the adhesion of solidified ink or the like, should be provided. 
     The primary object of the present invention is to provide a liquid delivery system superior in terms of practicality, that is, a liquid delivery system, the ink reservoir (liquid storing container) of which is exchangeable, and is capable of reliably delivering ink while generating and maintaining a stable amount of negative pressure, and also to provide a liquid storing container usable in such a liquid delivery system. 
     Another object of the present invention is to provide various inventions related to a head cartridge or the like with which the aforementioned liquid delivery system is usable. 
     The specific means in the present invention for accomplishing the above described objects will be become apparent from the understanding of the structures described below. 
     According to a characteristic aspect of the present invention, the liquid delivery system comprises: a negative pressure generating member holding chamber, which is provided with a liquid delivery portion for outward ink delivery, and an air vent portion, and stores therein a negative pressure generating member for retaining liquid therein; and a liquid storing container, which is exchangeably connectable to the negative pressure generating member holding chamber, and forms a virtually sealed space except for the joint portion by which it is connected to the negative pressure generating member holding chamber, wherein the liquid storing container to be connected to the negative pressure generating member holding container is provided with an atmospheric air introduction groove which is for displacing the liquid delivered from the liquid storing container, with the gas, by introducing gas into the liquid reservoir, and which is located at the joint portion of the ink reservoir, by which the ink reservoir is connected to the negative pressure generating member holding container. 
     According to another characteristic aspect of the present invention, a liquid storing container, which is exchangeably connectable to a negative pressure generating member holding chamber which is provided with a liquid delivery portion for outward ink delivery and an air vent portion, and stores therein a negative pressure generating member for retaining liquid therein, forms a virtually sealed space except for the joint portion by which it is connected to the negative pressure generating member holding chamber, and stores liquid, is provided with an atmospheric air introduction groove which is for displacing the liquid delivered from the liquid storing container, with the gas, by introducing gas into the liquid reservoir, and which is located at the joint portion of the ink reservoir, by which the ink reservoir is connected to the negative pressure generating member holding container. 
     According to the above described liquid delivery system and liquid storing container, the atmospheric air introduction groove is replaced as the liquid reservoir is replaced. Therefore, the atmospheric air introduction groove does not malfunction, making it possible to provide a liquid delivery system capable of reliably delivering ink. Further, a portion of the liquid in the liquid storing portion can be moved into the negative pressure generating member storing container with the use of the capillary force of the negative pressure generating member at the time of the connection. Therefore, it is assured that the liquid within the liquid storing container is reliably delivered for usage, regardless of the state of liquid retention in the negative pressure generating member, at the joint portion, upon installation. 
     Further, according to another characteristic aspect of the prevent invention regarding the above described liquid delivery system and liquid storing container, the liquid storing container comprises a liquid storing portion which stores liquid and is capable of generating negative pressure by deforming in response to the liquid delivery therefrom, a shell for covering the liquid storing portion, and an air vent through which atmospheric air can be introduced between the shell and the liquid storing portion. 
     In the case of a structure comprising a liquid storing portion such as the one described above, the liquid storing portion is elastically deformable. Therefore, even if the air or the like introduced into the liquid storing portion expands in response to ambient changes, the effect of the expansion is cushioned by the elasticity of the liquid storing portion, which works in the direction to restore the liquid storing portion to the original shape. 
     The liquid delivery port of the liquid storing portion is desired to be sealed with a sealing member. This sealing member is desired to separate from the liquid delivery port after the connection of the liquid storing container to the negative pressure generating member holding container. The negative pressure generating member holding container holds the negative pressure generating member between the aforementioned atmospheric air introduction groove and air vent. 
     It is possible to provide the negative pressure generating member holding container with a groove which becomes integrated with the aforementioned atmospheric air introduction groove to allow gas-liquid exchange. 
     Further, according to another characteristic aspect of the present invention, a head cartridge is provided with a recording head portion which records images by ejecting the liquid delivered from the aforementioned negative pressure generating member holding container. 
     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 schematic drawing for depicting the ink container in the first embodiment of the present invention, usable with a liquid delivery system in accordance with the present invention: (a) and (e) are perspective views; (b) is a sectional view; and (c), and (d) are enlarged sectional views. 
     FIG. 2 is a schematic drawing for depicting how the ink reservoir and negative pressure generating member holding chamber of the ink container illustrated in FIG. 1 are connected to each other: (a) is a sectional view at the same plane as the one in FIG. 1, ( b ); and (b) is a sectional view of the liquid reservoir at a plane A—A in FIG. 1, ( b ). 
     FIG. 3 is a sectional drawing for describing the state of the ink container illustrated in FIG. 1, immediately before the beginning of its first usage: (a) is a sectional view at the same plane as the one in the FIG. 1, ( b ), and (b) is a sectional view of the liquid reservoir at the plane A—A in FIG. 1, ( b ). 
     FIG. 4 is a sectional drawing for describing the ink delivery stage of the ink container illustrated in FIG. 1; ( a ) is a sectional view at the same plane as the one in the FIG. 1, ( b ), and (b) is a sectional view of the liquid reservoir at the plane A—A in FIG. 1, ( b ). 
     FIG. 5 is a sectional drawing for describing the gas-liquid exchange stage of the ink delivery from the ink container illustrated in FIG.  1 : (a) is a sectional view at the same plane as the one in the FIG. 1, ( b ), and (b) is a sectional view of the liquid reservoir at the plane A—A in FIG. 1, ( b ). 
     FIG. 6 is a sectional drawing for describing the state of the ink container illustrated in FIG. 1 immediately before the exchange of the ink reservoir of the ink container: (a) is a sectional view at the same plane as the one in the FIG. 1, (b), and (b) is a sectional view of the liquid reservoir at the plane A—A in FIG. 1, ( b ). 
     FIG. 7 is a graph which shows the relationship between the amount of the ink delivery from the ink container illustrated in FIG. 1, and the negative pressure at the ink delivery port portion. 
     FIG. 8, ( a ) is a graph which shows the details of the negative pressure curve given in FIG. 7, and FIG. 8, ( b ) is a graph which describes the changes occurring, with the elapse of time, to the amount of the ink delivered from the ink storing portion, and the amount of the air introduced into the ink storing portion, as the ink is continuously delivered. 
     FIG. 9 is a detailed drawing of a portion of the negative pressure curve correspondent to the ink delivery period B in FIG.  8 . 
     FIG. 10 is a sectional view of the ink container, which describes the ink container action correspondent to the period a in FIG.  9 . 
     FIG. 11 is a sectional view of the ink container, which describes the ink container action correspondent to the period b in FIG.  9 . 
     FIG. 12 is a sectional view of the ink container, which describes the ink container action correspondent to the period c in FIG.  9 . 
     FIG. 13 is a detailed drawing of a portion of the negative pressure curve in an ink delivery period of another ink container, correspondent to the ink delivery period B in FIG.  8 . 
     FIG. 14 is a sectional view of the ink container, which describes the ink container action correspondent to the period a in FIG.  13 . 
     FIG. 15 is a sectional view of the ink container, which describes the ink container action correspondent to the period b in FIG.  13 . 
     FIG. 16 is a sectional view of the ink container, which describes the ink container action correspondent to the period c in FIG.  13 . 
     FIG. 17 is a graph which describes the actions in the ink container at the time of the ink reservoir exchange. 
     FIG. 18 is a sectional view of the ink container illustrated in FIG. 1, which describes a part of the mechanism for stabilizing the state of ink retention when the ambient condition changes. 
     FIG. 19 is a sectional view of the ink container illustrated in FIG. 1, which describes another part of the mechanism for stabilizing the state of ink retention when the ambient condition changes. 
     FIG. 20 is a sectional view of the ink container illustrated in FIG. 1, which describes another part of the mechanism for stabilizing the state of ink retention when the ambient condition changes. 
     FIG. 21 is a sectional view of the ink container illustrated in FIG. 1, which describes another part of the mechanism for stabilizing the state of ink retention when the ambient condition changes. 
     FIG. 22 is a graph which describes the changes occurring, with the elapse of time, to the amount of the ink delivery from the ink storing portion, and the volume of the ink storing portion, when the ambient condition, that is, the ambient pressure, of the ink container illustrated in FIG. 1 is changed from one unit of pressure to a pressure level of P (0&lt;P&lt;1). 
     FIG. 23 is a sectional view of the ink container in the third embodiment of the present invention, compatible with the liquid delivery system in accordance with the present invention, and describes the general structure thereof: (a) is a sectional view prior to the connection of the ink reservoir to the negative pressure generating member holding chamber, and (b) is a sectional view after the connection. 
     FIG. 24 is a sectional view of the ink container in the third embodiment of the present invention, compatible with the liquid delivery system in accordance with the present invention, and describes the general structure thereof: (a) is a sectional view of the ink container in which the ink reservoir is connected to the negative pressure generating member holding chamber, and (b) is a sectional view of the ink container at a plane indicated by a line B—B in (a). 
     FIG. 25 is a sectional view of the ink container in the fourth embodiment of the present invention, compatible with the liquid delivery system in accordance with the present invention, and depicts the general structure thereof: (a) is a perspective view, and (b) is a sectional view. 
     FIG. 26 is a perspective view of the ink container in accordance with present invention, and one example of positive pressure based performance recovery process for ink flow cutoff. 
     FIG. 27 is a perspective view of the ink jet recording apparatus usable with the liquid delivery system in accordance with the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments 
     Hereinafter, the details of the preferred embodiments of the present invention will be described based on the appended drawings. 
     In the following description of the preferred embodiments, the liquid used in the liquid delivery method and liquid delivery system in accordance with the present invention will be described as ink. However, liquid compatible with the present invention is not limited to ink, which is obvious. For example, it includes liquid used for processing recording medium in the field of ink jet recording, and the like. 
     (Embodiment 1) 
     FIG. 1 comprises schematic drawings for describing an ink container compatible with a liquid delivery system in accordance with the present invention: (a) is a perspective view of the ink container, and (b) is a sectional view of the ink container connected to a recording head. 
     An ink container  1  comprises a negative pressure generating member holding chamber  10 , and an ink reservoir  50  which is separable from the negative pressure generating member holding chamber  10 . 
     The negative pressure generating member holding chamber  10  comprises a shell  11  and a negative pressure generating member  13 . The shell  11  is provided with an ink delivery port  12  through which ink (inclusive of recording medium processing liquid and the like) is delivered from the negative pressure generating member holding chamber  10  to a recording head portion  60  or the like which records images by ejecting liquid from a liquid ejection port. The negative pressure generating member  13  is formed of porous material such as polyurethane foam or the like, and is held in the shell  11 . The shell  11  is also provided with an air passage  15  through which the negative pressure generating member  13  held in the shell  11  is exposed to the atmosphere. Adjacent to the air passage  15 , there is a buffer portion  16  which comprises ribs projecting from the inward surface of the shell. 
     In comparison, the ink reservoir  50  comprises a shell  51  (outer shell) and a shell  54  (inner shell). The inner shell  54  is the same in shape as, or similar to, the outer shell  54 , and perfectly conforms to the inward surface of the outer shell  51 . The internal space of the inner shell  54  constitutes an ink storing portion  53  in which ink is stored. The ink reservoir  50  also comprises an ink delivery port  52  through which the liquid within the liquid storing portion  53  is delivered to the negative pressure generating member holding chamber  10 . The inner shell  54  is flexible; in other words, the ink storing portion  53  is deformable in response to the ink delivery therefrom. Further, the inner shell  54  is provided with a portion  56  (pinch-off portion), which is welded to the outer shell  51  so that the inner shell  56  is fixed to the outer shell  51 . The outer shell  51  is provided with an air vent  52  so that atmospheric air can be introduced into the space between the outer and inner shells  51  and  54 . 
     The ink container is also provided with a gas-liquid exchange enhancing portion  59  comprising an atmospheric air introduction groove  53  for enhancing gas-liquid exchange, which will be described later, and a gas-liquid exchange passage  59   a . The negative pressure generating member holding chamber  10  is provided with an interface portion  14 , that is, an opening, with which the gas-liquid exchange enhancing portion  59  is fitted. In this embodiment, a portion of the atmospheric air introduction groove  58  and one of the end portions of the gas-liquid exchange passage  59   a  are connected to the negative pressure generating member  13 , at the interface portion  14 . The atmospheric air introduction groove  58  extends from the interface portion  14  to an ink delivery portion  52 , so that liquid is smoothly delivered. This liquid delivery process will be described later. 
     Referring to FIG. 1, ( e ), which is a schematic perspective view of the ink container in this embodiment, the pinch-off portion  56  illustrated in FIG. 1, ( b ), is also provided on the other side, that is, the ink delivery side, of the ink container. An ink container structured so that the pinch-off portion  56  is provided on the side illustrated in FIG. 1, ( b ), as well as on the ink delivery side, as described above, is desirable because of the advantage that the aforementioned atmospheric air introduction groove  58  can be easily formed with the use of the pinch-off portion  56  on the ink delivery side. Also referring to FIG. 1, ( e ), which is a schematic perspective view of the ink container in this embodiment, the atmospheric air introduction groove  58  in this embodiment is extended upward from the center portion of the gas-liquid exchange enhancing portion  59 . However, the position of the atmospheric air introduction groove  58  does not need to be limited to the one described above as long as the atmospheric air introduction groove  58  functions properly. 
     Next, referring to FIG. 1, ( d ), which is an enlarged view of the encircled portion of the FIG. 1, ( b ), the portion of the shell  11 , which corresponds to the interface between the negative pressure generating member holding chamber  10  and ink reservoir  50 , may be provided with a groove  17  which is integrated with the atmospheric air introduction groove  58  of the ink reservoir  50  which is removably connected to the negative pressure generating member holding chamber  10 . In other words, when the negative pressure generating member holding chamber  10  side is provided with an air introduction groove for displacing the ink in the ink storing portion with air, the ink reservoir  50  side may be also provided with a groove which is integrated with the atmospheric air introduction groove on the negative pressure generating member holding chamber  10  side to displace the liquid in the ink storing portion with air. 
     In the appended sectional views of the ink containers in accordance with the present invention, inclusive of FIG. 1, the portions of the negative pressure generating member  13 , in which ink is held, is hatched, and the ink in the spaces free of the negative pressure generating material, that is, the ink storing portion, atmospheric air introduction groove, or gas-liquid exchange passages, is represented by crosshatching. 
     The ink reservoir in this embodiment has six flat walls, being approximately in the form of a rectangular parallelepiped, and is provided with a cylindrical ink delivery port  52 . The largest wall of this rectangular parallelepiped is indirectly illustrated in FIG.  1 . The walls of the ink storing portion  53  are thinner at each of the corner portions, that is, the portions correspondent to the corner portions of the rectangular parallelepiped (hereinafter, corner portions inclusive of the cases in which corner portions are slightly rounded), than at the center portion of each wall; the thickness of each wall of the ink storing portion  53  gradually reduces from the center portion toward the corner portions, in such a way that the inward surface of each wall of the ink storing portion  53  slightly swells inward of the ink storing portion  53 . In other words, the directions in which the walls of the ink storing portion  53  swell are the same as the directions in which the walls of the ink storing portion  53  deform, enhancing the deforming action of the walls, which will be described later. 
     Further, each corner portion of the inner shell is structured of three walls. Therefore, the overall strength of the corner portions of the inner shell is greater than that of the center portion of each wall. However, since each wall is thinner at the corner portions than across the center portion, it is allowed to flex. The three walls of the corner portion are desired to be approximately the same in thickness. 
     Because FIG. 1 is a schematic drawing, it looks as if there is a space between the walls of the outer shell  51  and the walls of the inner shell  54 . However, the former and the latter may be in contact with each other as long as they are separable from each other. Obviously, there may be provided a microscopic space between them. 
     Next, referring to FIGS. 2-7, the liquid delivery action of the ink container illustrated in FIG. 1, which characterizes the present invention, will be described FIGS. 2-6 are schematic sectional drawings of the ink container illustrated in FIG. 1, the ink storing chamber of which is connected to the negative pressure generating member holding chamber, and the ink delivery port of the negative pressure generating member holding chamber of which is connected to the recording head  60 , and depicts, in numerical order, the sequential changes which occur to the ink container as ink is delivered through the recording head  60 . In each of FIGS. 2-6, (a) is a sectional view of the ink container at the same plane as that in FIG. 1, ( b ), and (b) is a sectional view of the liquid reservoir at a plane A—A in FIG. 1, ( b ). FIG. 7 is a graph which shows the relationship between the amount by which ink is delivered from the ink container, and the negative pressure at the ink delivery port portion. Its axis of abscissas represents the amount by which ink is delivered from the ink delivery port, and its axis of ordinates represents the negative (static) pressure at the ink delivery port portion. In FIG. 7, the changes in the negative pressure, which correspond to FIGS. 2-6, are indicated by the arrow marks. 
     FIGS. 2, ( a ) and ( b ), is a sectional drawing which shows the negative pressure generating member holding chamber and ink storing chamber prior to their connection. 
     Referring to FIGS. 2, ( a ) and ( b ), the ink delivery port  52  of the ink reservoir  50  is provided with a sealing member  57  for preventing the ink stored in the ink storing portion  53  from being released; the ink storing portion  53  of the ink reservoir  50  remains sealed from the atmospheric air. The inner shell  54 , i.e., the wall of the ink storing portion  53 , is configured so that its walls conform to the correspondent walls of the outer shell  51 , or at least, the positions of its corner portions correspond, one for one, to the positions of the corners of the outer shell  51  (this state is called the initial state). 
     When the sealing member  57  is removed, ink sometimes leaks out due to external force, temperature change, and/or pressure change. This problem can be reliably prevented by filling the storing portion  53  with ink by an amount slightly less than its full capacity so that the ink delivery portion  52  is provided with a slight negative pressure when the sealing member  57  is removed. 
     Also in consideration of the aforementioned ambient changes, the amount of the air contained in the ink storing portion  53  prior to its connection to the negative pressure generating member holding chamber is desired to be as small as possible. As for a method to be used for reducing the amount of air which is introduced into the ink storing portion  53  during the liquid injection into the ink storing portion  53 , there is a liquid injection method such as the one disclosed in Japanese Patent Application No. 200126/1997, for example. 
     In comparison, the negative pressure generating member  13  in the negative pressure generating member holding chamber  10  in FIG. 2, ( a ), contains ink in a certain portion of it. 
     The amount of the ink stored in the negative pressure generating member  13  depends upon the amount of the ink stored in the negative pressure generating member  13  during ink reservoir exchange, which will be described later. Therefore, some variation is permissible; it is not required that ink is uniformly retained in the negative pressure generating member  13  as depicted in the drawing. 
     Next, referring to FIGS. 3, ( a ) and ( b ), the ink reservoir  50  is connected to the negative pressure generating member holding chamber  10 . After their connection, the ink flows, as indicated by an arrow mark in FIG. 3, ( a ), until the internal pressures of the negative pressure generating member holding chamber  10  and ink reservoir  50  become equal, that is, equilibrium is realized. In this state, the ink delivery portion  12  is provided with negative pressure (this state is called ink delivery starting state). 
     At this time, the ink flow which causes the aforementioned equilibrium will be described in detail. 
     First, the gas-liquid exchange enhancing portion  59  is inserted into the interface portion  14  of the negative pressure generating member holding chamber  10 , and the sealing member  57  is pulled out. As the sealing member  57  is pulled out, the atmospheric air introduction groove  58  and gas-liquid exchange passage  59   a  become directly connected to the negative pressure generating member  13 . As a result, an ink path is formed between the ink within the ink storing portion  53  and the negative pressure generating member  13  within the negative pressure generating member holding chamber  10 . In case air is present in the interface portion  14  in the state depicted in FIG. 2, ( a ), the air moves into the ink storing chamber  53  (this air is not illustrated in FIG.  3 ). As the ink path is formed, the ink begins to flow from the ink storing portion  53  into the negative pressure generating member  13  because of the capillary force of the negative pressure generating member  13 . As this ink flow begins, the walls of the inner shell  54  begin to deform, starting from the center portion of the largest wall, in the direction to decrease the internal volume of the ink storing portion  53 . Meanwhile, the wall of the outer shell  51  function to prevent the displacement of the corner portions of the inner shell  54 . Therefore, the ink storing portion  53  is affected by the force generated by ink consumption in the direction to deform the ink storing portion  53 , as well as the resiliency of the walls of the inner shell  54  which works in the direction to restore the initial state (FIG. 2) of the ink storing portion  53 , generating negative pressure by the amount proportional to the degree of deformation, without sudden change. The spaces between the inner and outer shells  54  and  51  are connected to the outside air through the air passage  55 . Therefore, the atmospheric air is introduced between the inner and outer shells  54  and  51 . As for the ink introduction into the atmospheric air introduction groove  58 , when the capillary force of the atmospheric air introduction groove  58  is greater than the negative pressure generated by the ink storing portion  53 , as in this embodiment, the atmospheric air introduction groove  58  is filled with ink, 
     As the ink flow begins, and the ink is filled into the negative pressure generating member  13 , the ink level in the negative pressure generating member  13  reaches above the top end of the atmospheric air introduction groove  58 , and eventually, the atmospheric air introduction groove  58  is cut off from the outside air. Then, the outflow of the ink from the ink reservoir  50  and the correspondent inflow of the outside air into the ink reservoir  50 , that is, gas-liquid exchange, begin to occur only through the negative pressure generating member holding chamber  10 . As a result, the ink flow continues until the static negative pressure in the ink reservoir  50  becomes equal to the static negative pressure in the negative pressure generating member holding chamber  10 . 
     More specifically, in the above described state, the negative pressure on the negative pressure generating member holding chamber side is greater than that on the ink reservoir side. Therefore, ink continues to flow from the ink reservoir  50  into the negative pressure generating member holding chamber  10  until the internal negative pressures in both chambers become equal. As the ink flow continues, the amount of the ink held in the negative pressure generating member  13  in the negative pressure generating member holding chamber  10  continues to increase. As is evident from the above description, the ink flow from the ink reservoir  50  into the negative pressure generating member holding chamber  10  occurs without introduction of gas into the ink reservoir  50  through the negative pressure generating member  13 . The levels of the static negative pressures for the two chambers should be set to an appropriate value (α in FIG. 7) according to the type of liquid jet recording means (unillustrated), such as a recording head, to be connected to the ink delivery port  12 , so that ink does not leak from the liquid jet recording means after the state of equilibrium in terms of internal pressure is realized between the two chambers. 
     The smallest amount of ink which flows from the ink storing portion  53  into the negative pressure generating member  13  equals the amount of ink which is necessary to raise the ink level in the negative pressure generating member  13  to the top end (position of the gas-liquid interface, which will be described later) of the atmospheric air introduction groove  58 , whereas the largest amount of ink which flows from the ink storing portion  53  into the negative pressure generating member  13  equals the amount of ink to exactly fill up the negative pressure generating member  13 . Therefore, the amount of the ink which is possible to flow into the negative pressure generating member  13  can be determined based on the largest and smallest amounts of ink which flows into the negative pressure generating member  13 , while taking into consideration the variation in the amount of the ink held in the negative pressure generating member  13  prior to the connection of the ink reservoir  50  to the negative pressure generating member holding chamber  10 , and the thus determined amount of ink and the value α of the negative pressure when the ink container is in the state of equilibrium in terms of internal pressure can be used to choose the proper material and proper thickness for the walls of the ink storing portion  53 , for the negative pressure generating member  13 . 
     Further, since the amount of the ink held in the negative pressure generating member  13  prior to the connection of the ink reservoir  50  to the negative pressure generating member holding chamber  10  varies from one negative pressure generating member  13  to another, some regions of the negative pressure generating member  13  remain unfilled with ink even after the state of equilibrium is realized between the ink reservoir  50  and negative pressure generating member holding chamber  10 . These regions can be used, along the buffer portion, as buffer regions against the changes in temperature and pressure, which will be described later. 
     However, when there is a possibility that the pressure at the ink delivery port becomes positive due to presence of an abnormally large amount of ink in the negative pressure generating member  13  when equilibrium in terms of internal pressure is realized, a counter measure may be taken; a performance recovery operation may be carried out by a suctioning means with which the liquid jet recording apparatus main assembly is provided, so that a small amount of ink is removed. 
     As for the formation of the ink path within the gas-liquid exchange passage  59   a  at the time of the connection, the ink path may be formed using the impact from the connection, or by applying pressure to the ink storing portion  53 , more specifically, by applying pressure to the shell  51 , at the time of the connection. Also, an arrangement may be made to keep the internal pressure of the ink storing portion  53  negative prior to the connection, so that this negative pressure can enhance the movement of the gas within the gas-liquid exchange passage  59   a  into the ink storing portion  53 . 
     Next, the ink in the ink container begins to be consumed by the recording head  60  through the ink delivery port  12 , as shown in FIG.  4 . During this initial stage of ink consumption, both the ink within the ink storing portion  53  and the ink held in the negative pressure generating member  13  are consumed, with the value of the static negative pressure in the ink storing portion  53  and negative pressure generating member  13  remaining balanced while increasing (first stage of ink delivery). 
     In other words, as the ink is consumed through the ink delivery port  12 , the ink level in the negative pressure generating member  13  in the negative pressure generating member holding chamber  10  lowers, and the ink storing portion  53  deforms further; the center portion of each wall of the ink storing portion  53  steadily displaces inward of the ink storing portion  53 . 
     During this deformation, the pinch-off portion  56  (welding portion) functions to regulate the deformation of the walls of the inner shell  54 , so that the ink storing portion walls (inner shell walls) without the pinch-off portion  56  begin to deform and separate from the correspondent walls of the outer shell  51 , ahead of the ink storing portion wall with the pinch-off portion. In this embodiment, the pair of ink storing portion walls with the larger size deform at approximately the same time. Therefore, the ink storing portion  53  smoothly deforms. 
     While the ink container is in the state depicted in FIG. 4 the static negative pressure gradually increases in proportion to the amount of ink delivery through the ink delivery port  12  as shown by the portion of the graph in a period A in FIG.  7 . Also in this first stage of ink delivery, it does not occur that air enters the ink storing portion  53  through the gas-liquid exchange passage  59   a.    
     As the ink delivery from the ink delivery port  12  continues further, air begins to be introduced into the ink storing portion  53  as shown in FIG. 5 (hereinafter, this state will be referred to as the gas-liquid exchange stage, or second stage of ink delivery). 
     During this second stage of ink delivery, the liquid level in the negative pressure generating member  13  remains approximately stable at the top end portion of the atmospheric air introduction groove  58  (position of the gas-liquid interface), and as the air enters the ink storing portion  53  through the air vent  15 , atmospheric air introduction groove  58 , and gas-liquid exchange passage  59   a , ink flows from the ink storing portion  53  into the negative pressure generating member  13  in the negative pressure generating member holding chamber  10  through the ink delivery port  12 . 
     Therefore, as ink is consumed by the recording head  60  as a liquid jet recording means, the absorbent member is replenished with ink in response to the consumption so that a stable amount of ink remains in the negative pressure generating member  13 . Also, this introduction of air into the ink storing  53  keeps the negative pressure within the ink container virtually stable while keeping the shape of the ink storing portion virtually the same during this gas-liquid exchange stage. Therefore, the ink delivery to the liquid jet recording means remains stable. When the ink container is in the state depicted in FIG. 5, the static negative pressure in the ink container remains virtually stable in spite of the ink delivery as depicted by the portion of the graph in the period C in FIG. 7 
     As the ink delivery from the ink delivery port  12  continues further, the ink within the ink storing portion  53  continues to be consumed until it virtually runs out as shown in FIG.  6 . Then, the ink remaining in the negative pressure generating member holding chamber  10  begins to be consumed. When the ink container is in the state depicted in FIG. 6, the negative pressure increases as shown by the portion of the graph correspondent to the period C in FIG. 7 in proportion to the amount of the ink delivery from the ink delivery port  12 . After the state of the ink container reaches this stage, even if the ink reservoir  50  is separated from the negative pressure generating member holding chamber  10 , there is little risk that ink will leak from the interface portion  14 . Therefore, the ink reservoir  50  from which ink has been depleted may be replaced with a fresh ink reservoir such as the one depicted in FIG.  2 . 
     The ink delivery action from the ink container illustrated in FIG. 1 is as described above. In other words, as the ink reservoir  50  is connected to the negative pressure generating member holding chamber  10 , ink flows until the internal pressures in the negative pressure generating member holding chamber  10  and ink reservoir  50  become equal to each other, that is, until the ink container becomes ready for delivering ink. Thereafter, ink begins to be consumed by the liquid jet recording means. As the ink consumption begins, both the ink held in the ink storing portion  53  and the ink held in the negative pressure generating member  13  are consumed, with the values of the static negative pressure generated by the ink storing portion  53  and negative pressure generating member  13  remaining balanced while increasing, until air begins to introduced into the ink storing portion  53 . Thereafter, the ink remaining in the negative pressure generating member holding chamber  10  begins to be consumed after going through the gas-liquid exchange stage in which as the atmospheric air is introduced into the ink storing portion  53 , the ink is consumed while the level of the gas-liquid interface is maintained constant by the negative pressure generating member  13  so that the negative pressure is kept constant in spite of the continuous ink consumption. 
     As described above, the ink consumption from the ink container in accordance with the present invention goes through a stage (first stage of ink delivery) in which the ink within the ink storing portion  53  is consumed without the introduction of the outside air into the ink storing portion  53 . Therefore, only the requirement regarding the internal volume of the ink reservoir  50  is to take into consideration the amount of the outside air introduced into the ink storing portion  53  at the time of the connection of the ink reservoir  50  to the negative pressure generating member holding chamber  10 . In other words, the ink container in accordance with the present invention offers a benefit that it can counter the ambient changes in spite of the flexible requirement regarding the internal volume of the ink reservoir  50 . 
     Further, the ink container in accordance with the present invention allows virtually the entire amount of ink in the ink storing portion  53  to be consumed, properly functions even if air is present in the gas-liquid exchange passage  59   a  at the time of ink reservoir exchange, and allows ink reservoir exchange regardless of the amount of ink in the negative pressure generating member  13 , making it possible to provide an ink delivery system, the ink reservoir of which can be satisfactorily exchanged without the provision of an ink remainder amount detection mechanism required by the prior arts. 
     Further, referring to FIG. 7, in order for the negative pressure to increase in proportion to the amount of ink delivery (period A), remain steady for a period of time (period B), and then, further increase in proportion to the amount of ink delivery (period C), the atmospheric air is introduced before the opposing walls of the ink storing portion  53  come into contact with each other. In other words, it is desirable that the state of the ink container changes from the state in the period A to the state in the period B before the opposing walls of the ink storing portion  53  come into contact with each other, because, the ratio at which the negative pressure changes in response to the amount of the ink delivery from the ink storing portion is different between the period before and the period after the opposing walls with the larger size come into contact with each other. 
     Also according to the present invention, the ink container is structured so that even when air is contained in the ink storing portion, for example, when the ink container is in the second stage of ink delivery, the ambient changes are dealt with by a solution different from the one based on the prior arts. 
     FIG. 8 is a graph in which the curved line represents one example of the actual change in the negative pressure correspondent to the theoretical change in the negative pressure shown by in FIG.  7 . In FIG. 8, the portions of the curved line designated by (1), (2), and (3) correspond to the ink delivery stages prior to the beginning of air-liquid exchange, during the air-liquid exchange, and after the air-liquid exchange. FIG. 9 is a graph which shows the details of the change in the negative pressure represented by the curved line in the period B in FIG.  8 . FIGS. 10-12 are sectional views of the ink container in this embodiment, which correspond to periods a, b, and c of the graph, and describe the actions occurring in the ink container. FIG. 13 is a drawing which shows the detail of the negative pressure curve in another embodiment, correspondent to the curved line in the period B in FIG.  8 . FIGS.  14 - 16  are sectional views of the ink container in this embodiment, and describe the actions in the ink container correspondent to the periods a′, b′ and c′ of FIG.  13 . In FIGS. 10-12, and FIGS. 14-16, a drawing (a) is a sectional view of the ink container at the same plane as the one for FIG. 1, ( b ), and a drawing (b) is a sectional view of the ink reservoir at the same plane as the sectional plane A—A for FIG. 1, ( b ). In these drawings, which will be used for the following description of the present invention, the deformations and the like of the ink reservoir are slightly exaggerated to make the description easier to understand. 
     (1) Description of Ink Delivery Actions Correspondent to Period ( 1 ) in FIG. 8 
     The ink delivery action (ink delivery action prior to the beginning of the air-liquid exchange) shows three patterns, each of which will be separately described. Each pattern is included in this application of the present invention. The pattern of the ink delivery action changes in response to various factors, for example, magnitude of the capillary force of the negative pressure generating member, thickness of the walls of the ink reservoir, type of the material for the ink reservoir, and also the interactions among them. 
     &lt;First Pattern Correspondent to Period ( 1 ) in FIG.  8 &gt; 
     This pattern occurs when the ink storing portion  53  is dominant over the negative pressure generating member  13  in regulating the negative pressure. Specifically, this pattern occurs with higher frequency when the walls of the inner shell  54  of the ink reservoir  50  are relatively thick, and also, relatively high in rigidity. 
     In the initial stage of ink delivery, the ink in the negative pressure generating member  13  is delivered, because the resistance to the delivery of the ink in the negative pressure generating member  13  is smaller than the resistance to the delivery of the ink in the ink reservoir  50 . After the initial delivery of the ink in the negative pressure generating member  13  as described above, ink is delivered from both the ink storing portion  53  and negative pressure generating member  13 , with balance being maintained between the negative pressures in the negative pressure generating member  13  and ink reservoir  50 . As the ink is delivered from the ink reservoir  50 , the walls of the inner shell deform inward of the ink reservoir  50 . 
     &lt;Second Pattern Correspondent to Period ( 1 ) in FIG.  8 &gt; 
     This pattern occurs when the negative pressure generating member  13  is dominant over the ink storing portion  53  in regulating the negative pressure, which is contrary to the first pattern. Specifically, this pattern occurs with higher frequency when the walls of the inner shell  54  of the ink reservoir  50  are relatively thin, and also, relatively low in rigidity. 
     In the initial stage of ink delivery, ink is delivered from the ink reservoir  50 , because the resistance to the ink delivery from the ink reservoir  50  is smaller than the resistance to the ink delivery from the negative pressure generating member  13 . After the initial ink delivery from the ink reservoir  50 , ink is delivered from both the ink storing portion  53  and negative pressure generating member  13 , with balance being maintained between the negative pressures in the negative pressure generating member  13  and ink reservoir  50  as described above. 
     &lt;Third Pattern Correspondent to Period ( 3 ) in FIG.  8 &gt; 
     This pattern tends to occur when the negative pressure is equally regulated by the negative pressure generating member  13  and ink storing portion  53 . 
     In this pattern, in the initial stage of ink delivery, ink is delivered from both the negative pressure generating member  13  and ink storing portion  53 , with balance being maintained between the negative pressures in the negative pressure generating member  13  and ink reservoir  50 . This balance is maintained as the state of the ink container changes from the initial stage of ink delivery to the air-liquid exchange stage, which will be described later. 
     (2) Description of Ink Delivery Action Correspondent to Period ( 2 ) of FIG. 8 
     Next, the ink delivery in the air-liquid exchange stage will be described. The ink delivery action shows two patterns. These pattern will be described in further detail, with reference to an enlarged drawing of the portion of the curved line correspondent to the period ( 2 ) in FIG.  8 . 
     &lt;First Pattern Correspondent to Period ( 2 ) in FIG.  8 &gt; 
     This pattern occurs when the ink storing portion  53  is dominant over the negative pressure generating member  13  in regulating the negative pressure. More specifically, this pattern occurs with higher frequency when the walls of the inner shell  54  of the ink reservoir  50  are relatively thick, and also, relatively high in rigidity. 
     In the gas-liquid exchange stage, the atmospheric air is introduced into the ink reservoir  50  from the negative pressure generating member holding chamber  10  (period a in FIG.  9 ). This air introduction is for easing the negative pressure imbalance between the negative pressure generating member holding chamber  10  and ink reservoir  50 . As the result of air introduction into the ink reservoir  50 , the walls of the inner shell  54  of the ink reservoir  50  slightly deform outward as shown in FIG.  10 . Ink is supplied from the ink reservoir  50  to the negative pressure generating member holding chamber  10  as the air is introduced into the ink reservoir  50 , and as a result, the liquid level in the negative pressure generating member holding chamber  10  rises slightly (FIG.  10 →FIG.  11 ). 
     In this embodiment, as more air is introduced into the ink reservoir  50 , first, ink is delivered from the negative pressure generating member  13 , and as a result, the liquid level in the negative pressure generating member holding chamber  10  moves downward (curved line in period b in FIG. 9) (FIG.  11 ). 
     After the above stage, ink is delivered from both the negative pressure generating member  13  and ink storing portion  53 , with balance being maintained between the negative pressures in the two chambers. As a result, the liquid level in the negative pressure generating member  13  falls further, and the walls of the inner shell  54  of the ink reservoir  50  deforms inward of the ink reservoir  50  (curved line in period c in FIG. 9) (FIG.  12 ). 
     After the continuance of the above state for a certain length of time, the atmospheric air begins to be introduced into the ink storing portion  53  through the atmospheric air introduction groove  58 . As a result, the internal pressure increases as the curved line in period a in FIG. 9 indicates. 
     &lt;Second Pattern Correspondent to Period ( 2 ) in FIG.  8 &gt; 
     This pattern occurs when the negative pressure generating member  13  is dominant over the ink storing portion  53  in regulating the negative pressure, which is contrary to the first pattern. More specifically, this pattern tends to occur when the walls of the inner shell  54  of the ink reservoir  50  are relatively thin, and also, relatively low in rigidity. 
     As described above, in the gas-liquid exchange stage, air is introduced from the negative pressure generating member holding chamber  10  into the ink reservoir  50  (period a′ in FIG.  13 ). As the result of this air introduction into the ink reservoir  50 , the walls of the inner shell  54  of the ink reservoir  50  slightly deform outward as shown in FIG.  14 . Ink is supplied from the ink reservoir  50  into negative pressure generating member holding chamber  10  in response to the air introduction. As a result, the liquid level in the negative pressure generating member holding chamber  10  rises slightly (FIG.  14 →FIG.  15 ). 
     In this pattern, as more air is introduced into the ink reservoir  50 , ink is delivered dominantly from the ink reservoir  50 . In this stage, the negative pressure does not change much; it gently increases, because of the characteristics of the ink reservoir  50  in thickness and rigidity of wall. As the result of this ink delivery, the walls of the inner shell  54  of the ink reservoir  50  gradually deform inward in response to the ink delivery (period b′ in FIG.  13 ). 
     During this period, almost no ink is delivered from the negative pressure generating member  13 . Therefore, the liquid level in the negative pressure generating member  13  hardly changes. 
     Also during this period b′ in FIG. 13, ink is delivered from both the negative pressure generating member  13  and ink storing portion  53 , with balance being maintained between the negative pressures in the former and the latter, until the period c′ in FIG. 13 begins. In this period c′ in FIG. 13, the liquid level in negative pressure generating member  13  falls as described above, and the walls of the inner shell  54  of the ink reservoir  50  deform inward (period c′ in FIG.  13 )(FIG.  16 ). 
     After the period c′ in FIG. 13, atmospheric air is introduced into the ink storing portion  53  through the atmospheric air introduction groove  58 . Then, the beginning of the next ink delivery sub-cycle, correspondent to the period a′ in FIG. 13, begins. 
     (3) Description of Ink Delivery in a period ( 3 ) in FIG. 8 
     Lastly, the ink delivery in the period ( 3 ) in FIG. 8, that is, the ink delivery after the gas-liquid exchange period, will be described. 
     In this period, that is, the period after the gas-liquid exchange period ends as the result of the delivery of more ink, the ink within the ink reservoir  50  is virtually depleted, and therefore, ink is delivered mainly from the negative pressure generating member  13 . The ink delivery in this period occurs in two patterns, which will be described below. 
     &lt;First Pattern Correspondent to Period ( 3 ) in FIG.  8 &gt; 
     Here, a case in which the internal pressure of the ink storing portion becomes virtually the same as the atmospheric pressure after the gas-liquid exchange period will be described. 
     At the end of the gas-liquid exchange period, the ink within the ink reservoir  50  has been virtually entirely consumed. Therefore, generally speaking, meniscuses have been formed in the atmospheric air introduction groove  58 , the passage between the negative pressure generating member holding chamber  10  and ink reservoir  50 , and/or the negative pressure generating member  13 . However, as the liquid level in the negative pressure generating member  13  drops below the top end of the atmospheric air introduction groove  58 , these meniscuses break due to the carriage vibration or the like. As a result, a clear air passage is established between the outside of the ink container and the ink storing portion  53  through the atmospheric air introduction groove  58 , virtually equalizing the internal pressure of the ink storing portion  53  to the atmospheric pressure. As a result, the walls of the inner shell  54  of the ink reservoir  50 , which have deformed inward, deform outward because of their resiliency. However, they generally fail to return to their original positions. This is because, as described above, the walls deform inward in response to the ink delivery from the ink reservoir  50 , and if the deformation of the walls exceeds a certain point, they tend to buckle, and once they buckle, they tend to fail to return to their original states. Thus, even after the internal pressure of the ink storing portion  53  becomes the same as the atmospheric pressure, the walls tend to fail to return to their original positions. 
     After the internal pressure of the ink storing portion  53  becomes the same as the atmospheric pressure, and the walls of the inner shell  54  return to virtually the original positions, ink is delivered from the negative pressure generating member  13 . As a result, the liquid level in the negative pressure generating member  13  falls, causing the negative pressure to increase in inverse proportion to the ink delivery. 
     &lt;Second Pattern Correspondent to Period ( 3 ) in FIG.  8 &gt; 
     Here, a case in which even after the liquid level of the negative pressure generating member  13  falls below the top end portion of the atmospheric air introduction groove  58 , the internal pressure of the ink reservoir remains negative, will he described. 
     As described above, the internal space of the ink storing portion  53  is cut off from the outside air by the meniscuses within the atmospheric air introduction groove  58 , passage between the negative pressure generating member holding chamber  10  and ink reservoir  50 , and/or negative pressure generating member  13 . Sometimes, ink continues to be consumed under this condition, causing the liquid level in the negative pressure generating member  13  to continue to fall. If this happens, the ink in the negative pressure generating member  13  is consumed while the walls of the inner shell  54  of the ink reservoir  50  remain deformed inward. 
     Also in the above described situation, however, the aforementioned meniscuses break due to causes such as the carriage vibration, ambient change, and/or the like, during the consumption of the ink, allowing the internal pressure of the ink storing portion  53  to become virtually equal to the atmospheric pressure. Also in this case, the walls of the inner shell  54  of the ink reservoir  50  return to virtually their original states. 
     As described above, the ink container system structured in accordance with the present invention is characterized in that its pressure fluctuation (amplitude γ) during the gas-liquid exchange period is relatively large compared to the pressure fluctuation of an ink container system based on the prior arts. 
     This is because, in the case of the ink container system structure in accordance with the present invention, before the gas-liquid exchange begins, the walls of the inner shell  54  are caused to deform inward by the ink delivery from the ink reservoir  50 , as described with reference to Period ( 1 ) in FIG.  8 . Therefore, the walls of the inner shell  54  always remain under the force generated by their own resiliency in the direction to deform them outward. Thus, the amount of the atmospheric air which enters the ink storing portion  53  during the gas-liquid exchange period, to ease the pressure difference between the negative pressure generating member  13  and ink storing portion  53 , sometimes exceeds a predetermined amount, which tends to cause an increase in the amount of the ink delivered from the ink reservoir  50  into the negative pressure generating member holding chamber  10 . In comparison, in the case of a conventional system, in which the ink reservoir does not deform, ink is delivered into the negative pressure generating member holding chamber  10  as soon as a predetermined amount of air enters. 
     For example, when in the solid printing mode, a large amount of ink is ejected all at once, causing ink to be rapidly delivered from the ink container. However, in the case of an ink container in accordance with the present invention, the amount of ink delivered through the gas-liquid exchange is relatively large compared to an ink container based on the prior arts, eliminating the possibility of temporary failure in ink delivery, and therefore, adding to reliability. 
     Also in the case of the structure in accordance with the present invention, ink is delivered while the walls of the inner shell  54  of the ink reservoir  50  remain inwardly deformed. Therefore, it is superior in buffering the effects of the external disturbances such as the carriage vibration, ambient changes, and the like. 
     At this time, the operation of the ink container during the above described ink consumption sequence, will be described from a different point of view with reference to FIG. 8, ( b ). 
     In FIG. 8, ( b ), the axis of abscissas stands for elapsed time, and the axis of ordinates stands for the amount of ink delivery from the ink storing portion, as well as the amount of air introduction into the ink storing portion. It is assumed that the amount of ink ejected from the ink jet head per unit period remains constant during this ink delivery period. 
     With the above provision, the amount of ink delivered from the ink storing portion is represented by a solid line ( 1 ), and the amount of air introduced into the ink storing portion is represented by a solid line ( 2 ). 
     A period from t 0  to t 1  corresponds to the period A in FIG. 8, ( a ), that is, the period prior to the gas-liquid exchange period. In this period, ink is ejected from the head, with balance being maintained between the negative pressures in the negative pressure generating member  13  and ink storing portion  53 , as described above. The ink delivery patterns in this example are the same as those described above. 
     Next, a period from t 1  to t 2  corresponds to the gas-liquid exchange period (period B) in FIG. 8, ( a ). During this period, the gas-liquid exchange continues based on negative pressure balance such as the one described above. Ink is delivered from the ink storing portion  53  as air is introduced into ink storing portion  53 , as depicted by the solid line ( 1 ) in FIG. 8, ( b ). It is not true that during this ink delivery process, ink is delivered from the ink storing portion  53  by the amount equal to the amount of the introduced air, immediately after the introduction of the air. As a matter of fact, ink is delivered by the amount equal to the total amount of the introduced air, a certain length of time after the air introduction. In other words, as is evident from this drawing, there is a difference in the timing with which the ink is delivered from the ink storing portion  53 , between the ink container in accordance with the present invention and the ink container based on the prior arts. The above described ink delivery sub-cycle is repeated during this gas-liquid exchange period, and eventually, the amounts of the air and ink within the ink storing portion  53  reverse at a certain point in time. 
     After the point t 2 , the period correspondent to the period C in FIG. 8, ( a ), that is, the post-gas-liquid exchange period, begins. During this period, the internal pressure of the ink storing portion  53  becomes virtually equal to the atmospheric pressure as described above. Then, the ink container is restored to the initial state of ink delivery by the resiliency of the walls of the inner shell  54  of the ink reservoir  50 . However, because of the aforementioned buckling of the walls, it does not occur that the ink container is completely restored to the initial state of ink delivery. Thus, the actual total amount Vc of the air introduced into the ink storing portion  53  is smaller than the theoretical capacity V of the ink storing portion  53  (V&gt;Vc). Also in this period, the ink in the ink storing portion  53  is completely consumed. 
     Next, the sequence which occurs when the ink reservoir  50  is exchanged during various stages of ink delivery will be described with reference to FIG.  17 . 
     (a) When the Ink Reservoir is Exchanged Prior to the Gas-Liquid Exchange Stage (FIG. 17, ( a )) 
     As described above, prior to the gas-liquid exchange stage, ink is consumed from both the negative pressure generating member  13  and ink reservoir  50 , with balance being maintained between the negative pressures in the former and latter. In this state, the negative pressure continues to increase in reverse proportion to the ink consumption, and the ink level in the negative pressure generating member  13  remains above the top end of the atmospheric air introduction groove. 
     If the ink reservoir  50  is exchanged during this stage, the ink in the ink reservoir  50  is supplied to the negative pressure generating member  13  as a fresh ink reservoir is connected, because, the internal pressure of the ink reservoir  50  is generally only slightly negative, although it is occasionally positive. As a result, the liquid level in the negative pressure generating member holding chamber  10  rises, and stabilizes as the negative pressures in the former and latter become balanced. Since there is the aforementioned buffer zone above the negative pressure generating member  13 , ink does not leak through the air vent  15  even if the liquid level rises. 
     As the ink reservoir  50  is connected, the negative pressure generally decreases, although the internal pressure occasionally turns positive. If it turns positive, it can be quickly changed to negative by carrying out a performance recovery operation or the like immediately after the connection, so that a proper amount of negative pressure is provided. After the connection, ink is consumed following the aforementioned consumption pattern. 
     In the case of a liquid delivery system in accordance with the present invention, even when the negative pressure generating member  13  in the negative pressure generating member holding chamber  10  is not filled with ink, adjacent to the gas-liquid exchange passage, the ink in the ink storing portion  53  can be moved into the negative pressure generating member  13  by using the capillary force in the negative pressure generating member holding chamber  10 , as long as an ink path is formed between the ink reservoir  50  and negative pressure generating member holding chamber  10 . Therefore, it is assured that, as long as the ink reservoir  50  is properly connected, the ink in the ink reservoir  50  can be used regardless of the state of ink retention in the negative pressure generating member  13 , adjacent to the interface portion  14 . 
     (b) When the Ink Reservoir is Exchanged During the Gas-Liquid Exchange Period (FIG. 17, ( b )) 
     During the gas-liquid exchange period, the liquid level in the negative pressure generating member  13  generally remains stable at the top end portion of the atmospheric air introduction groove  58 , and the walls of the inner shell  54  of the ink reservoir  50  remain inwardly deformed, as described above. 
     In this state, if the ink reservoir  50  is removed and an ink reservoir  50  in the initial state of ink delivery is connected, the ink in the ink reservoir  50  is supplied to the negative pressure generating member  13 , and the liquid level in the negative pressure generating member  13  rises; in other words, the liquid level rises above the atmospheric air introduction groove  58 . As a result, the walls of the inner shell  54  of the ink reservoir  50  deform inward, and yet, the internal pressure of the ink reservoir  50  remains slightly negative. 
     After the stabilization of the ink level, ink is consumed following the aforementioned consumption patterns (( 1 )- 1 -( 1 )- 3 ). Then, as the internal pressure reaches a predetermined negative level, the gas-liquid exchange begins. 
     (c) When the Ink Container is Exchanged After the Gas-Liquid Exchange Period (FIG. 12, ( c )) 
     After the gas-liquid exchange period, the liquid level in the negative pressure generating member  13  is below the top end portion of the atmospheric air introduction groove  58 , and the internal pressure of the ink reservoir  50  is approximately the same as the atmospheric pressure, as described above. The walls of the inner shell  54  have returned to their original states, or remain inwardly deformed, although the internal pressure of the ink reservoir  50  remains negative. 
     Also in this state, if the ink reservoir  50  is exchanged, the ink in the ink reservoir  50  is supplied to the negative pressure generating member side, causing the liquid level in the negative pressure generating member  13  to rise. In this case, the liquid level generally rises above the top end of the atmospheric air introduction groove  58 , although there is chance that the liquid level will settle below the atmospheric air introduction groove  58 . As the result of this ink delivery, the walls of the inner shell  54  of the ink reservoir  50  deform inward, and yet, the internal pressure of the ink reservoir  50  remains on the slightly negative side. 
     If the liquid level rises above the atmospheric air introduction groove  58 , the gas-liquid exchange begins after the aforementioned ink consumption process, whereas if the liquid level settles below the atmospheric air introduction groove  58 , the gas-liquid exchange immediately begins. 
     As described above, regardless of the ink consumption stage in which the ink reservoir  50  is exchanged, it is assured that a proper amount of negative pressure is generated to reliably deliver ink. 
     The ink container in accordance with the present invention is capable of absorbing the minute fluctuation in the negative pressure by the function of the ink storing portion  53 . In addition, in the case of the structure in accordance with the present invention, even in a situation in which air is contained in the ink storing portion  53 , for example, in the second stage of ink delivery, ambient changes can be dealt with by a problem solving method different from any of the prior methods. 
     Next, referring to FIGS. 18-21, and FIG. 22, the mechanism in the ink container illustrated in FIG. 1, which stabilizes the state of retention will be described. 
     FIGS. 18-21 are schematic sectional drawings of the ink container in accordance with the present invention, and depict the functions of the portion of the negative pressure generating member  13 , above the atmospheric air introduction groove  58 , as a buffering absorbent member, and the buffering function of the ink storing portion  53 . In these drawings, the sequential changes which occur in the ink container as the air within the ink storing portion  53  expands due to the drop in the atmospheric pressure and/or temperature increase when the ink container is in the state depicted in FIG. 5 (during the gas-liquid exchange period), are depicted in the order of the drawings. In these drawings, (a) is a sectional view correspondent to FIGS. 1, ( b ), and ( b ) is a sectional view of the ink reservoir at the same plane as the plane A—A in FIG. 1, ( b ). 
     As the air in the ink storing portion  53  expands due to the drop in the atmospheric pressure (or increase in temperature), pressure is applied to the walls ( 1 ) and liquid surfaces ( 2 ) as shown in FIGS. 9, ( a ) and ( b ). As a result, the internal volume of the ink storing portion  53  increases, and at the same time, a portion of the ink in the ink storing portion  53  flows into the negative pressure generating member holding chamber  10  side through the gas-liquid exchange passage  59   a . Since the internal volume of the ink storing portion  53  increases, the amount of the ink which flows into the negative pressure generating member holding chamber  10  (amount correspondent to the distance of the rising of the liquid level in the negative pressure generating member, illustrated in FIG. 20, by a referential character ( 3 )), is substantially smaller compared to an ink container with an inflexible ink storing portion. 
     In this situation, when this pressure change, which allows the internal volume of the ink storing portion  53  to increase, by easing the negative pressure in the ink storing portion  53 , is sudden, the amount of the ink which initially flows out through the gas-liquid exchange passage  59   a , is dominantly affected by the resistance of the walls of the inner shell  54  of the ink reservoir  50  against easing their inward deformation, and the resistance against forcing the ink to move into the negative pressure generating member  13  so that the ink is absorbed by the negative pressure generating member  13 . 
     In particular, in the case of this structure, the flow resistance of the negative pressure generating member  13  is greater than the resistance to the restoration of the initial state of the ink storing portion  53 . Therefore, as the air expands, the internal volume of the ink storing portion  53  increases as shown in FIGS. 18, ( a ) and ( b ). If the theoretical increase in the internal volume which will be caused by the air expansion is greater than the actually tolerable increase in the internal volume, the ink is forced to flow into the negative pressure generating member holding chamber  10  from the ink storing portion  53  through the gas-liquid exchange passage  59   a . In other words, the walls of the ink storing portion  53  function as the buffer against the ambient changes. Therefore, the ink movement within the negative pressure generating member  13  is eased, and as a result, the negative pressure at the ink delivery port stabilizes. 
     In this embodiment, the ink which flows into the negative pressure generating member holding chamber  10  is retained by the negative pressure generating member  13 . In this case, the amount of the ink in the negative pressure generating member holding chamber  10  temporarily increases, which causes the position of the gas-liquid interface to rise, as depicted in FIGS. 20, ( a ) and ( b ). Therefore, the internal pressure temporarily turns slightly positive as at the beginning of the usage, which is different from when the internal pressure is stable. However, the effects of this situation upon the ejection characteristics of a liquid jet recording means such as a recording head is small enough to cause no practical problem. Then, as the atmospheric pressure returns to the level prior to the pressure drop (returns to single unit of the atmospheric pressure), the ink which has been retained in the negative pressure generating member  13  after leaking into the negative pressure generating member holding chamber  10 , returns to the ink storing portion  53 , and at the same time, the ink storing portion  53  restores the previous volume. 
     Next, referring to FIG. 22, the process which occurs to change the unstable state of the ink container created by the change in the atmospheric pressure, into the stable state illustrated in FIGS. 21, ( a ) and ( b ) will be described. 
     This process is characterized in that the position of the interface between the ink retained in the negative pressure generating member, and the air in the negative pressure generating member holding chamber, changes in response to not only the amount of the ink delivered from the ink storing portion  53 , but also the change in the volume of the ink storing portion itself. 
     The relationship between the amount of the ink absorbed by the negative pressure generating member  13 , and the ink reservoir  50 , is as follows. That is, the internal volume of the negative pressure generating member holding chamber  10  is determined in consideration of the prevention of the ink leak from the air vent  15  or the like which occurs at the time of the aforementioned ambient pressure drop and/or temperature change. More specifically, the maximum amount of ink which must be absorbed by the negative pressure generating member  13  is determined in consideration of the amount of the ink forced out of the ink reservoir  50  under the worst condition, and the amount of the ink which is retained by the negative pressure generating member  13  during the ink delivery virtually exclusively from the ink reservoir, and then, the size of the negative pressure generating member  13  is determined based on the thus determined maximum amount of the ink which must be absorbed by the negative pressure generating member  13 . Then, the negative pressure generating member holding chamber  10  is provided with an internal volume sufficient to accommodate the negative pressure generating member  13  with the thus determined size. 
     FIG. 22 is a graph which shows the changes in the rate of ink delivery from the ink storing portion, and the volume of the ink storing portion, after the change in the ambience of the ink container; more specifically, how the rate of ink delivery from the ink storing portion, and the volume of the ink storing portion, change with elapsed time when the atmospheric pressure drops from single unit of the atmospheric pressure to P (0&lt;P&lt;1) at time t. In FIG. 22, the axis of abscissas stands for time (t), and the axis of ordinates stands for the amount of the ink delivery from the ink storing portion, and the volume of the ink storing portion. The change in the amount of the ink delivery with the elapsed time is represented by a solid line ( 1 ), and the change in the volume of the ink storing portion with the elapsed time is represented by a solid line ( 2 ) 
     Times t a , t b , t c , and t d  in FIG. 22 correspond to the states of ink container depicted in FIGS. 18,  19 ,  20 , and  21 . 
     Referring to FIG. 22, the expansion caused by the sudden change in the ambience is mainly dealt with by the ink reservoir  50  before the negative pressure balance between the negative pressure generating member holding chamber  10  and ink reservoir  50  finally stabilizes. Therefore, the timing of ink delivery from the ink reservoir  50  into the negative pressure generating member holding chamber  10  caused by the sudden change in the ambience of the ink container is delayed. 
     Thus, it is possible to provide an ink delivery system which is tolerant of the expansion of the gas introduced by gas-liquid exchange, that is, capable of restoring a proper amount of negative pressure while the ink reservoir  50  is in action, under various conditions of usage, and therefore, is capable of reliably delivering ink regardless of the ambient condition. 
     In the case of an ink delivery system in accordance with the present invention, the material for the negative pressure generating member  13  and ink storing portion  53  is optional. Also, the volumetric ratio between the negative pressure generating member holding chamber  10  and ink reservoir  50  is optional; it may be selected as appropriate. For example, even an ink container with the aforementioned ratio of 1:2 had no problem in practical usage. If the buffering effect of the ink reservoir  50  is of particular concern, all that is necessary is to increase the amount of the deformation allowed for the ink storing portion  53  within the limit of its elastic deformation. 
     In order to enhance the aforementioned buffering function of the ink storing portion  53 , it is desired that the amount of the air present in the ink storing portion  53  when the deformation of the ink storing portion  53  is relatively small is small, in other words, the amount of the air present in the ink storing portion  53  prior to the gas-liquid exchange stage after the connection is as small as possible. 
     Up to this point, the gist of the present invention was described with reference to the first embodiment of the present invention. Next, other embodiments of the present invention will be described. Needless to say, the components in the first embodiment, and the components in the following embodiments, may be employed in combination when possible. 
     (Embodiment 2) 
     FIG. 23 is a schematic sectional view of the ink container in the second embodiment of the present invention, which is compatible with a liquid delivery system in accordance with the present invention. In the drawing, (a) and (b) are sectional views of the ink container before and after the connection of the ink reservoir to the negative pressure generating member holding chamber, respectively. 
     This embodiment is different from the first one in that the ink container is structured so that the portion of the negative pressure generating member  13 , adjacent to the interface portion  14  between the negative pressure generating member holding chamber  10  and ink reservoir  50 , is compressed when the ink reservoir  50  is connected to the negative pressure generating member holding chamber  10 . Otherwise, this embodiment is the same in structure as the first embodiment. 
     With the provision of the above described structure, the negative pressure generating member  13  remains compressed adjacent to the interface portion  14  after the connection of the ink reservoir. Therefore, the ink delivery from the ink storing portion  53  into the negative pressure generating member  13  is more stable. Further, ink is smoothly supplied from the ink storing portion  53  into the negative pressure generating member  13  at the time of ink reservoir exchange. 
     (Embodiment 3) 
     FIG. 24 is a schematic sectional view of the ink container in the third embodiment of the present invention, which is compatible with a liquid delivery system in accordance with the present invention. 
     This embodiment is different from the first embodiment in that the ink reservoir  150  is positioned straight above the negative pressure generating member holding chamber  110 . Otherwise, it is the same as the first embodiment. In other words, the negative pressure generating member holding chamber  110  comprises a shell  111 , a negative pressure generating member  113  contained in the shell, an ink delivery port  112 , an air vent  115 , a buffer portion  116 , and an outside air introduction groove  117 , and the ink reservoir  150  comprises an outer shell  151 , an inner shell  154 , the shape of which matches the internal contour of the outer shell  151 , and the internal space of which constitutes an ink storing portion  153 , an air vent  155 , a pinch-off portion  156 , and an ink delivery port  152 . 
     (Embodiment 4) 
     FIG. 25 is a schematic sectional view of the ink container in the fourth embodiment of the present invention, which is compatible with a liquid delivery system in accordance with the present invention. In the drawing, (a) and (b) are perspective and sectional views of the ink container, respectively. 
     In this embodiment, a head cartridge  300  integrally comprises a liquid ejecting portion  301  capable of ejecting plural choices of liquid different in color (in this embodiment, three colors: yellow, magenta, and cyan), and three negative pressure generating member holding chambers  410 ,  510 , and  610 , which are different in the color of the liquid contained therein. To this head cartridge  300 , ink reservoirs  450 ,  550 , and  650  are removably connected. 
     In order to assure that each ink reservoir is connected to the correct negative pressure generating member holding chamber, the head cartridge  300  is provided with a holder portion  302 , which partially covers the exterior surfaces of the ink reservoir; the ink reservoirs are provided with latch levers  459 ,  559 , and  659  with an engagement pawl; and the guiding member is provided with engagement holes  303   a ,  303   b , and  303   c  in which the correspondent engagement pawls engage, so that the ink reservoirs remain properly connected. The ink reservoirs  450 ,  550 , and  650  are virtually the same in shape. Therefore, identification labels (unillustrated) may be provided to prevent an installation error. Obviously, three ink reservoir compartments of the holder may be differentiated in shape as a part of the mechanism for preventing the installation error. In this case, the ink reservoirs may be differentiated in volume, according to the frequency of usage of each color ink reservoir. 
     This embodiment may be modified so that the plurality of negative pressure generating member holding chambers  410 ,  510  and  610  can be individually separated from the liquid ejecting portion. It is needless to say that the color of the liquid stored in each ink reservoir may be different from the aforementioned ones, and also the number and combination of ink reservoirs are optional. 
     Further, in this embodiment, the ink reservoirs are separable from each other. However, they may be inseparably integrated. 
     An example of an ink reservoir  750  which comprises a plurality of inseparable sub-containers is shown in FIG. 4, ( b ), which is a sectional view of the ink container. The ink reservoir  750  is provided with ink storing portions  753   a ,  753   b , and  753   c  which are provided with ink delivery ports  752   a ,  752   b , and  752   c , which are sealed with sealing members  757   a ,  757   b , and  757   c , correspondingly. The ink storing portions  753   a ,  753   b , and  753   c  correspond to the negative pressure generating member holding chambers  410 ,  510 , and  610 , and can be connected thereto by the ink delivery ports  752   a ,  752   b , and  752   c . The ink reservoir  750  illustrated in FIG. 25, ( b ) has a plurality of ink storing portions different in size; the ink storing portions are differentiated in internal volume to match the frequency of usage of the liquid contained therein. It should be noted that inseparably integrating the ink reservoirs as in this modification is also effective to prevent the ink reservoir installation error. 
     (Miscellaneous Embodiments) 
     In the preceding sections, some of the modifications of the first embodiment were described. Next, miscellaneous modifications of the preceding embodiments will be described, which are compatible with the preceding embodiments unless noted otherwise. 
     &lt;Structure of Negative Pressure Generating Member Holding Chamber&gt; 
     First, the descriptions of the structure of the negative pressure generating member holding chamber in the preceding embodiments will be supplemented. 
     As for the material for the negative pressure generating member to be stored in the negative pressure generating member holding chamber (negative pressure generating member container), felted fiber, a thermoformed pack of fiber, or the like may be used in addition to porous material such as polyurethane foam. 
     In the above descriptions of the preceding embodiments, the gas-liquid exchange passage (junction) was depicted as a tubular passage. However, it may be in any configuration as long as it does not interfere with gas-liquid exchange during the gas-liquid exchange period 
     In the preceding embodiments, the empty space (buffer portion) in the negative pressure generating member was located in the top portion of the negative pressure generating member holding chamber. However, this space may be filled with an additional amount of the material for the negative pressure generating member, which does not normally retain liquid. With the presence of the additional volume of the negative pressure generating member material in the buffer space, the ink which flows into the negative pressure generating member holding chamber at the time of the aforementioned change in ambience can be held in this portion of the negative pressure generating member. 
     &lt;Structure of Ink Reservoir&gt; 
     Next, an additional description will be made of the structures of the ink reservoirs in the preceding embodiments. 
     In the case of an ink container, in which the ink reservoir is separable from the negative pressure generating member holding chamber, the portion of the ink reservoir, at which the ink reservoir is connected to the negative pressure generating member holding chamber, is provided with a sealing member as a member for preventing liquid and/or air from leaking from the joint portion between the two chambers at the time of the connection, and also for preventing the ink within the ink storing portion from leaking out prior to the connection. 
     The ink reservoirs in the preceding embodiments are manufactured by direct blow molding. More specifically, the outer shell and inner shell (ink storing portion) of the ink reservoir, which are separable from each other, are formed by uniformly expanding a pair of cylindrical parisons against a mold with a more or less polygonal internal space by air blow. These ink reservoirs may be replaced with ink reservoirs which comprise a flexible pouch, and a metallic spring or the like placed in the pouch to generate negative pressure in response to ink delivery. 
     However, blow molding is advantageous in that use of blow molding makes it easier not only to manufacture an inner shell, that is, the wall of the ink storing portion, the shape of which is the same as, or similar to, the shape of the outer shell, but also to change the choice and/or thickness of the material for the wall of the ink storing portion to produce a proper amount of negative pressure. Further, using thermoplastic resin as the material for the inner and outer shells makes it possible to provide an easily recyclable ink reservoir. 
     At this point, the description given above as to the structure of the “outer shell” in each of the preceding embodiments, and the particular features of the “outer shell”, which affect the “inner shell” will be supplemented. 
     In each of the preceding embodiments, the ink reservoir is manufactured by blow molding. Therefore, the structure of the inner shell is such that the thickness of each wall is less at the corner portions than at the center portion of each wall. This is also true of the outer shell. The inner shell is placed in the outer shell in such a way that each wall of the inner shell is laid upon the inward surface of the correspondent wall of the outer shell. 
     In other words, the outward surface of each of the inner shell interfaces with the inward surface of the correspondent wall of the outer shell. As a result, the walls of the inner shell, that is, the walls of the ink storing portion, slightly bulge inward, since the thickness of the walls of the outer shell gradually increase from the corners toward the center as described above. Further, since the thickness of each wall of the inner shell also increases from the corners toward the center, the inward surface of each wall of the inner shell further bulges inward of the ink storing portion. The effects of this structural arrangement are most prominently displayed by the walls with the largest size. Therefore, as far as the present invention is concerned, it is not necessary that all the walls of the inner and outer shells are structured as described above. In other words, all that is necessary is that at least the wall with the largest size is provided with this structural arrangement. The distance the inward surface of the wall of the inner shell bulges inward does not need to exceed 2 mm, and the distance the outward surface of the wall of the inner shell bulges inward does not need to exceed 1 mm. In the case of the smaller size wall, these distances may fall within the range of measurement error. However, this structural arrangement, which makes the inward surface of the ink storing portion inwardly bulge, is one of the factors which establishes the order in which each of the walls of the ink container in the form of a virtually polygonal prism, deforms. In other words, this feature is one of the preferable aspects of the present invention. 
     Next, the description of the structure of the outer shell will be supplemented. In the preceding description of the outer shell, regulating the deformation of the corner portions of the inner shell was listed as one of its functions. All that is necessary for the outer shell to be enabled to perform this function is that the outer shell is structured so that it is not deformed by the deformation of the inner shell, and that it surrounds all the corner portions of the inner shell (outer shell functions as a corner covering member). Therefore, the outer shell may be in such a form that comprises corner portions with a panel structure, and metallic rods or the like which connect these corner portions, in addition to being in the aforementioned fully wall clad form. Further, the outer shell may be mesh structured. 
     In the case of an exchangeable ink reservoir, ink flow is sometimes cut off for various reasons between the adjacency of the gas-liquid exchange passage of the negative pressure generating member and the adjacency of the ink delivery port, when the ink reservoir is exchanged. If this happens, the ink flow can be easily restored simply by manually and temporarily squeezing the elastically deformable outer shell, along with the inner shell, to force the ink within the ink reservoir into the negative pressure generating member holding chamber. This recovery process based on pressure application can be automatically, rather than manually, carried out by providing a recording apparatus, which will be described later, with a pressure based ink flow recovering means. In the case of an ink reservoir with a partially exposed inner shell, the portion to which pressure is applied may be only the exposed portion of the inner shell. 
     In the preceding embodiments, the ink storing portion is virtually in the form of a polygonal prism. However, the shape of the ink storing portion does not need to be limited to a polygonal prism. In other words, from the standpoint of accomplishing the first object of the present invention, the ink storing portion may be in any shape as long as the shape allows the ink storing portion to deform, in response to outward delivery of the ink, sufficiently to provide the ink storing portion with negative pressure. As for the material for the outer shell, it may be plastic, metal, cardboard, or the like. 
     In order to provide the ink storing portion with the aforementioned buffering function, the ink storing portion must be capable of elastic deformation, so that it restores the pre-deformation shape as the substance stored therein expands. In other words, the ink storing portion is required to deform within a range in which the deformation of the ink storing portion is reversible. It is true that, occasionally, the rate at which the negative pressure is fluctuated by the deformation caused by the outward delivery of ink suddenly changes (for example, in the case of deformed portions coming into contact with each other). Therefore, the configuration of the ink storing portion is desired to be such that, even if the extent of the deformation is within the reversible range, the first stage of ink delivery is completed, that is, the ink storing portion is readied for the second stage of ink delivery, before the situation in which the aforementioned sudden change in negative pressure might occur is created. 
     The material for the liquid storing container in accordance with the present invention may be any material as long as it allows the inner and outer shells to separate from each other. Further, a plurality of materials may be used to make the walls of the inner and outer shell laminar. The ink reservoir structure in accordance with the present invention makes it possible to employ an inner shell which has walls with higher elasticity compared to the reservoir structure which comprises only the ink reservoir which doubles as the negative pressure generating member holding container. In consideration of the effects of the reservoir material upon ink or the like which is contained in the reservoir, polyethylene, polypropylene, and the like, for example, are preferable. 
     Next, a method for forming the atmospheric air introduction groove will be described. If a direct blow molding method is employed to manufacture an ink reservoir, a groove is formed on the inward side of the pinch-off portion. This groove can be used as the atmospheric air introduction groove. 
     Preferably, the atmospheric air introduction groove should be molded in during the blow molding process, so that the length and depth of the atmospheric air introduction groove can be regulated. 
     &lt;Ink Container&gt; 
     In the preceding embodiments, the ink reservoir is made removably connectable to the negative pressure generating member holding chamber. Therefore, the ink reservoir is desired to be provided with a sealing member such as an O-ring so that the joint between the two chambers is sealed by the sealing member to prevent ink from leaking out of the joint. 
     &lt;Liquid Delivery Action and Ink Delivery System&gt; 
     Next, the description of the liquid delivery action and ink delivery system will be supplemented. 
     The ink container (ink delivery system) in each of the preceding embodiments goes through four stages: the pre-usage stage in which no connection has been established between the ink reservoir and negative pressure generating member holding chamber; the initial stage of ink delivery immediately after the connection; the first stage of ink delivery; and the second stage of ink delivery. 
     Obviously, the ink container in each of these embodiments can be modified. As the first of such modifications, the ink container may be modified so that its ink delivery process does not include the gas-liquid exchange stage, i.e., the second stage of ink delivery. In the case of this type of modification, the ink in the ink storing portion is consumed without introducing the outside air into the ink storing portion. Therefore, the only factor which must be taken into consideration to regulate the internal volume of the liquid storing container is the volume of the air introduced into the ink reservoir at the time of the connection. In other words, this modification has merit in that the ink container is enabled to deal with ambient changes, in spite of the relaxed regulation over the internal volume of the ink reservoir; the modified structure can accomplish the first object of the present invention. However, if the space utilization efficiency for the ink storing portion is taken into consideration, the structure, such as in each of the preceding embodiments, which provides the ink container with the gas-liquid exchange stage which follows the first stage of ink delivery, is superior to this modified structure. 
     The second modification deals with such a situation that the liquid level in the negative pressure generating member holding chamber prior to the connection is higher than the position of the gas-liquid interface, which sometimes occurs when the ink container is in the state depicted in FIG.  2 . More specifically, among the ink movements which occur to ready the ink container for the initial ink delivery, and were described with reference to FIG. 3, the unidirectional ink movement into the negative pressure generating member holding chamber caused by the capillary force, does not occur. 
     The third modification deals with a situation in which the rate at which ink is consumed by a recording head is extremely high. More specifically, when the ink consumption rate of a recording head is extremely high, the negative pressure is not always balanced between the two chambers. Instead, the ink in the negative pressure generating member holding chamber is primarily consumed until the amount of the difference between the negative pressures in the two chambers exceeds a predetermined value, and as the amount of the difference exceeds the predetermined value, the ink in the ink reservoir moves into the negative pressure generating member holding chamber side. 
     The aforementioned ink container, the two chambers of which always remain united, is different from the ink container, the two chambers of which are separable, only in that in the case of the former, the state of the ink container at the beginning of usage is the same as the state of the ink container at the end of the usage. Otherwise, there is no difference between the former and the latter. Thus, the descriptions given above regarding the effects of the preceding embodiments also apply to these modified versions of the ink container. 
     &lt;Liquid Jet Recording Apparatus&gt; 
     Lastly, an ink jet recording apparatus in which the ink container in the first embodiment of the present invention, depicted in FIG. 1, is mounted to record images will be described. FIG. 27 is a perspective view of the ink jet recording apparatus in which the ink container in the first embodiment of the present invention has been mounted, and depicts the general structure thereof. 
     In FIG. 27, a head unit  4010  and an ink container  100  are supported by a carriage  4520  of the main assembly of the ink jet recording apparatus. More specifically, they are removably attached to the carriage  4520  with the use of an unillustrated positioning means, and a connecting plate  5300  which is rotatively supported by an axis. 
     The forward and backward rotation of a motor  5130  is transmitted to a lead screw  5040  through driving force transmission gears  5110  and  5090 , and rotates the lead screw. The carriage  4520  is provided with a pin (unillustrated) which engages with the spiral groove  5050  of the lead screw  5040 . With the provision of the above arrangement, the carriage  4520  is shuttled in the longitudinal direction of the apparatus. 
     A referential character  5020  designates each of the caps for capping the front surface of the corresponding recording head within the recording unit. The cap  5020  is used to recover the performance of the recording head by suctioning the recording head through the internal passage of the cap, with the use of an unillustrated suctioning means. The cap  5020  is moved by the driving force transmitted through the gear  5080  and the like, to cover the recording head surface in which ejection orifices are present. Adjacent to the caps  5020 , a cleaning blade is provided, which is not illustrated. This blade is supported so that it can be moved in the upward or downward direction in the drawing. The blade shape is not limited to a specific one. Needless to say, any of the known cleaning blades can be employed as the cleaning blade for this ink jet recording apparatus in this embodiment. 
     The apparatus in this embodiment is structured so that these operations of capping, cleaning, and suctioning for performance recovery, are carried out at their appropriate positions by the function of the lead screw  5050  when the carriage  4520  is at the home position. However, other structures are also acceptable as long as they make the these components perform their functions with known timing. 
     Here, the advantages of mounting an ink container in accordance with the present invention on a carriage which shuttles as described above will be described. 
     The ink reservoir of the ink container in accordance with the present invention is a deformable component, being therefore enabled to cushion the ink vibration caused by the scanning movement of the carriage, by its deformation. In order to prevent the fluctuation of the negative pressure caused by the scanning movement of the carriage, it is desired that a part or parts of the corner portions of the ink storing portion are not separated from the internal surface of the outer shell, or that the corner portions of the ink storing portion remain close to the internal surface of the outer shell, even if they are separated. Further, in the case of an ink storing portion, such as the one in this embodiment, it is desired to be mounted on the carriage in such a way that the pair of opposing walls with the largest size become perpendicular to the direction of the scanning movement of the carriage. Such an arrangement can enhance the aforementioned ink vibration cushioning effect. 
     Further, a recording apparatus may be provided with a pressure based performance recovery means for indirectly pressing the inner shell of the ink reservoir through the outer shell of the ink reservoir, as described in the section &lt;Structure of Ink Reservoir&gt;. In the case of such an arrangement, it is recommended that the recording apparatus is provided with: a liquid presence detecting means  5060  which comprises a light emitting means and a light receiving means, and detects the presence (absence) of ink from the state of the reflection of the light projected through the ink reservoir, an ejection failure detecting means (unillustrated) which detects the ejection failure of a recording head, and a controlling means (unillustrated), because, such provision makes it possible to prevent ink flow from being cut off between the adjacency of the gas-liquid exchange passage of the negative pressure generating member and the adjacency of the ink delivery port, provided that an operational sequence such as the one described below is adopted. 
     The sequence is as follows. First, if the ejection failure of the head nozzles is detected after the ink reservoir is replaced with a fresh one, and the standard performance recovery operation, i.e., the suction based operation, is carried out with the use of the cap  5020 , the normal operation is restored by carrying out the pressure based performance recovery operation. Also, if, during the usage of the ink reservoir, the state of “ink presence” is detected by the liquid presence detecting means, and also, the ejection failure of the nozzles of the head correspondent to the ink reservoir in which ink is present is detected by the ejection failure detecting means, but the ejection failure could not be remedied by the standard performance recovery operation, i.e., the suction based operation, the normal operation can be restored by carrying out the positive pressure based performance recovery operation. In either case, it is desired that the recording head portion correspondent to the ink container for which the positive pressure based performance recovery operation is to be carried out is capped to prevent unexpected ink leak from the recording head portion. 
     The choice of the liquid presence detecting means does not need to be limited to an optical type such as the aforementioned one. Other types such as a dot counting type may be employed, or different types may be employed in combination. 
     As described above, according to the present invention, the atmospheric air introduction groove for enhancing the gas-liquid exchange is provided as a part of the ink reservoir separable from a negative pressure generating member holding chamber, and therefore, does not malfunction, making it possible to provide a liquid delivery system capable of reliably delivering ink, and a liquid storing container compatible with such a system. 
     The liquid storing container is provided with a liquid storing portion capable of producing negative pressure by deforming in response to the outward liquid delivery therefrom. Therefore, the liquid storing container is capable of preventing the ink in the ink storing portion from flowing into the negative pressure generating member holding chamber, or is capable of reducing the amount of the ink in the ink storing portion which flows into the negative pressure generating member holding chamber, even if the air introduced into the ink storing portion expands in response to ambient changes. As a result, liquid ejection remains stabilized. 
     Further, the liquid storing container used for the liquid delivery system in accordance with the present invention is capable of moving the liquid in the liquid storing container into the negative pressure generating member with the use of the capillary force of the negative pressure generating member holding chamber at the time of the installation of the liquid storing portion. Therefore, it is assured that the ink in the liquid storing container becomes available for delivery, regardless of the state of liquid retention in the negative pressure generating member, adjacent to the joint, upon simple installation of the ink storing container. 
     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.