Patent Publication Number: US-7905587-B2

Title: Liquid vessel and method of manufacturing the same

Description:
BACKGROUND 
     1. Technical Field 
     The present invention relates to a liquid vessel having a liquid lead-out portion for ejecting liquid and a flexible liquid containing portion formed of a film for containing liquid, and a method of manufacturing the liquid vessel. 
     2. Related Art 
     There is a liquid ejecting apparatus which includes a liquid container and a liquid ejecting head, ejects liquid output from the liquid container from the liquid ejecting head, and discharges the liquid to a target which faces the liquid ejecting head. An example of such a liquid ejecting apparatus is an inkjet recording apparatus. 
     A variety of inkjet recording apparatuses including a carriage, a recording head functioning as a liquid ejecting head mounted in the carriage and an ink cartridge functioning as a liquid container have been developed. 
     Such inkjet recording apparatuses supply ink from the ink cartridge to the recording head and discharge the ink from a nozzle formed in the recording head, while the carriage is moved relative to the recording medium as a target, thereby performing printing with respect to the recording medium. 
     Among such inkjet recording apparatuses, there is a configuration in which the ink cartridge is not mounted in a carriage (called an off carriage type), in order to reduce load on the carriage or downsize the apparatus. Such an ink cartridge includes an ink pack for containing ink and a casing for containing the ink pack. 
       FIG. 11  is a conventional example of the ink pack. 1    1    FIGS. 11-14  should be labeled as “Conventional” or “Prior Art” if prior art under at least one section of 35 U.S.C. §102. 
     The ink pack  100  is disclosed in JP-A-2005-59320 and includes a cylindrical liquid lead-out portion  101  for ejecting ink and a flexible liquid containing portion  102  formed of a film for containing the ink. 
     The liquid lead-out portion  101  is formed of a hard resin material and has a valve tool which is mounted in an inkjet recording device and opens a flow path when an ink supply needle of the recording apparatus is inserted thereinto. 
     As shown in  FIGS. 12 to 14 , the liquid containing portion  102  has a vessel structure including a first sealing portion  121  obtained by welding both ends  111   c  and  111   d  of a film  111  including a lamination structure of a metal film  111   a  and a resin film  111   b  for a gas barrier property to each other to form a body portion  113 , a gore portion  123  placed under tension in a circumferential direction of the body portion  113  at side surfaces thereof by a pair of mountain-shaped folding portions  115   a  and  115   b  folded at opposed side surfaces of the body portion  113  in a longitudinal direction and a valley-shaped folding portion  116  between the pair of mountain-shaped folding portions  115   a  and  115   b , a second sealing portion  125  for sealing an opening  113   a  of the body portion  113  in a state in which the liquid lead-out portion  101  is inserted into the opening  113   a  of one side of the body portion  113 , and a third sealing portion  127  for sealing an opening  113   b  of the other side of the body portion  113 . 
     The sealing portions  121 ,  125  and  127  are sealed by thermal welding in a state in which the surfaces of the resin films  111   b  of the film  111  overlap with each other. 
     However, in an inkjet recording apparatus for business use, in order to reduce the replacement frequency of the ink pack  100  due to an ink shortage to improve the operation rate of the apparatus, a large-capacity ink pack  100  is required. 
     If the capacity of the ink pack  100  is increased, rigidity of the liquid containing portion  102  needs to be increased by thickening the film  111  in order to prevent the film  111  from being damaged due to low strength. 
     However, a liquid containing portion  102  having high rigidity due to thickening of the film  111  is difficult to deform due to a restoring force of the film  111  which may cause inconvenience. 
     For example, in the conventional ink pack  100 , since the liquid containing portion  102  before use is completely filled with ink, as shown in  FIG. 15 , the gore portion  123  perfectly expands such that the pair of mountain-shaped folding portions  115   a  and  115   b  are unfolded so that internal angles thereof are close to about 90 degrees. Then, the gore portion  123  is difficult to fold even when storage amount is reduced by the consumption of the ink. When the liquid containing portion  102  is pressurized from the outside by pressurized air such that the ink in the liquid containing portion  102  is supplied from the liquid lead-out portion  101  to the recording apparatus, the peripheral portion of the gore portion  123  is difficult to crush. Thus, there is a problem that the amount of residual ink is increased. 
     If the film  111  used in the liquid containing portion  102  is thinned in order to prevent the above-described problem from occurring, for example, the ink is shaken at the time of transport and the gore section is repeatedly bent. In this case, cracking occurs in the metal film  111   a  configuring the film  111 , the gas barrier property of the liquid containing portion  102  is reduced, and the storage property of the stored ink deteriorates. 
     SUMMARY 
     An advantage of at least one embodiment of the invention is that it provides a liquid vessel capable of preventing a folding property of a gore portion from being impaired even though a film used in a liquid containing portion is thickened such that the amount of residual liquid can be reduced. 
     According to an aspect of at least one embodiment of the invention, there is provided a liquid vessel including a liquid lead-out portion for ejecting liquid out and a flexible liquid containing portion formed of a film for containing the liquid, wherein the liquid containing portion includes a first sealing portion having a body portion having a tubular shape formed by adhering both ends of one film to each other, a second sealing portion which includes gore portions having a pair of mountain-shaped folding portions folded at opposed side surfaces of the body portion in a longitudinal direction and a valley-shaped folding portion between the pair of mountain-shaped folding portion that seals an opening in a state in which the liquid lead-out portion is inserted into the opening of the body portion, and a third sealing portion that seals another opening of the body portion, and wherein the mountain-shaped folding portions configuring the gore portions have mountain-shaped maintenance portions which maintain a state in which inner surfaces of facing films at least partially contact each other. 
     By this configuration, since the liquid is completely filled in the liquid containing portion before use, the gore portions completely expand, but the pair of mountain-shaped folding portions of the gore portions has a state at the time of folding by providing the mountain-folding-shape maintenance portions. Accordingly, a folding property of the gore portions is not impaired. Accordingly, when the liquid containing portion is pressurized from the outside by pressurized air such that the liquid in the liquid containing portion is supplied from the liquid lead-out portion to a liquid ejecting apparatus and the amount of contained ink is reduced, the gore sections are rapidly shrunken. 
     That is, a folding property of the gore portions is not impaired although a thick film is used in the liquid containing portion in order to increase the amount of contained liquid. In addition, since the liquid containing portion is difficult to be crushed, the amount of residual ink can be reduced. 
     The mountain-shaped maintenance portions may be formed by welding the inner surfaces of the facing films to each other. 
     By this configuration, since a dedicated component is not required for forming the mountain-folding-shape maintenance portions, the structure of the pair of mountain-shaped folding portions configuring the gore portions is simplified and thus cost can be reduced. 
     The mountain-shaped maintenance portions may be intermittently formed in a longitudinal direction of the mountain-shaped folding portion. 
     By this configuration, since the mountain-shaped maintenance portions can be formed by spot-welding the inner surfaces of the facing films, the workability of the mountain-shaped maintenance portions can be improved and the productivity of the liquid containing portion can be improved. Compared with the case where continuous welding is performed, the output of a welding device is reduced and equipment cost and process cost can be reduced. 
     Both ends of the mountain-shaped folding portions configuring the gore portions each may be formed in a triangular shape in which a contact area between the inner surfaces of the facing films is gradually widened. 
     By this configuration, since the inner surfaces of the facing film contact each other at both ends of the longitudinal direction of the pair of mountain-shaped folding portions configuring the gore portions, the gore portions are gradually folded from both ends of the longitudinal direction when the amount of liquid contained in the liquid containing portion is reduced, such that an operation for folding the gore portions is smoothly performed. 
     The contained liquid may be ink and the liquid vessel may be mounted in an inkjet recording apparatus to be used as an ink vessel for supplying the ink to the recording apparatus. 
     By this configuration, since the liquid containing portion is adequately crushed in accordance with the consumption of the ink contained in the liquid containing portion, the amount of residual ink due to the deformation which occurs due to the crush of the gore sections  36  is minimized and printing cost of the inkjet recording apparatus can be reduced. 
     According to another aspect of at least one embodiment of the invention, there is provided a method of manufacturing a liquid vessel, the method including: forming gore portions by forming a pair of mountain-shaped folding portions folded in a longitudinal direction at opposed side surfaces of a body portion having a tubular shape obtained by adhering both ends of one film to each other and forming a valley-shaped folding portion between the pair of mountain-shaped folding portions; forming mountain-shaped maintenance portions which maintain a state in which inner surfaces of facing films at least partially contact each other; sealing an opening in a state in which a liquid lead-out portion for directing liquid out is inserted into the opening of the body portion; filling the liquid in a vessel portion formed by sealing the opening; and sealing another opening of the body portion in a state in which the liquid is filled in the vessel portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIG. 1  is an exploded perspective view of an ink cartridge used in an ink pack of a liquid vessel according to a first embodiment of the invention. 
         FIG. 2  is a perspective view of the ink pack shown in  FIG. 1 . 
         FIG. 3  is a perspective view showing a method of manufacturing a liquid containing portion of the ink pack shown in  FIG. 2 . 
         FIG. 4  is a plan view showing the method of manufacturing the liquid containing portion of the ink pack shown in  FIG. 2 . 
         FIG. 5  is a cross-sectional view taken along line V-V of  FIG. 4 . 
         FIG. 6  is a cross-sectional view taken along line VI-VI of  FIG. 4 . 
         FIG. 7  is a perspective view when viewed in a direction VII of  FIG. 4 . 
         FIG. 8  is a view explaining an operation of a gore portion shown in  FIG. 6 . 
         FIG. 9  is a plan view of an ink pack of a liquid vessel according to a second embodiment of the invention. 
         FIG. 10  is a cross-sectional view of main portions of an ink pack of a liquid vessel according to a third embodiment of the invention. 
         FIG. 11  is a perspective view of an ink pack as a known liquid vessel. 
         FIG. 12  is a perspective view showing a method of manufacturing a liquid containing portion of the ink pack shown in  FIG. 11 . 
         FIG. 13  is a plan view showing the method of manufacturing the liquid containing portion of the ink pack shown in  FIG. 11 . 
         FIG. 14  is a cross-sectional view taken along line XIV-XIV of  FIG. 13 . 
         FIG. 15  is a view explaining a problem of the ink pack shown in  FIG. 11 . 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Hereinafter, liquid vessels according to embodiments of the invention will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is an exploded perspective view of an ink cartridge used in an ink pack of a liquid vessel according to a first embodiment of the invention. 
     The ink cartridge  20  shown in  FIG. 1  includes a casing  23  which is detachably mounted in a cartridge mounting portion of an inkjet recording apparatus (not shown) and an ink pack  24  contained in the casing  23 . 
     The casing  23  includes a cover  25  and a body casing  26 . 
     The body casing  26  has a box shape with an open upper surface. A support port  28  is formed in a front surface  26   a  of the body casing  26 , and the support port  28  communicates the inside and the outside of the body casing  26  with each other. A pressurization air lead-in port  29  connected to a pressurization air supply device of a recording apparatus is formed in the front surface  26   a  of the body casing  26  on the right side of the support port  28 . The pressurization air lead-in port  29  communicates the inside and the outside of the body casing  26  with each other. 
     The pressurization air lead-in port  29  is connected to the pressurization air supply device provided in the cartridge mounting portion and functions as a flow path for directing pressurized air into a gap between the casing  23  and the ink pack  24 , when the ink cartridge  20  is mounted in the cartridge mounting portion of the recording apparatus (not shown). The pressurization air lead-in port  29  is opened to communicate with the atmosphere such that the ink pack  24  is not pressurized by an internal pressure variation of the casing  23 , when the ink cartridge  20  is not mounted in the cartridge mounting portion. 
     In the body casing  26 , a partition wall  26   c  configuring a closed space for pressurizing the ink pack  24  is provided. 
     The partition wall  26   c  is formed on a bottom surface of the body casing  26  separated from the inner surface of the body casing  26  with a small interval therebetween, has an opened upper surface, and has a portion protruding toward the front surface  26   a  of the casing  23 . The partition wall  26   c  supports the ink pack  24  contained therein. 
     The pressurization air lead-in port  29  is opened in the inner surface of the partition wall  26   c . An upper end surface of the partition wall  26   c  in which the ink pack  24  is contained is adhered to a film (not shown). 
     A space defined by the partition wall  26   c , the bottom surface of the body casing  26  and the film is sealed in a closed state. Pressurized air supplied from the pressurization air supply device of the recording apparatus is directed into the space through the pressurization air lead-in port  29 . 
     A groove  26   d  is formed between the inner surface of the body casing  26  and the outer surface of the partition wall  26   c . A plurality of engagement portions  26   e  are formed in the groove  26   d.    
     The first engagement portions  26   e  are mounted between the partition wall  26   c  and the body casing  26  and have a rod-shaped or U-shaped cross section. 
     The cover  25  is a rectangular parallelepiped plate shape and has second engagement portions  25   a  protruding from the cover  25  downward at the edges thereof. 
     The second engagement portions  25   a  include pawls  25   b  at the front ends thereof. The pawls  25   b  protrude from the cover  25  outwardly and are formed so as to be engage with the first engagement portions  26   e  provided in the groove  26   d  of the body casing  26 . The cover  25  covers the opening of the body casing  26  in a state in which the ink pack  24  is contained in the partition wall  26   c  and the film is adhered to the partition wall  26   c.    
     Next, the ink pack  24  of the liquid vessel according to a first embodiment of the invention will be described with reference to  FIG. 1  and  FIGS. 2 to 8 . 
     The ink pack  24  according to the present embodiment includes a vessel portion  31  as a body portion configuring the liquid containing portion  30  for containing ink as liquid. A supply member  27  protrudes from one side of the vessel portion  31  as a liquid lead-out portion. 
     As shown in  FIGS. 1 and 3 , the supply member  27  includes a main body  27   a  formed of resin such as polypropylene, and a supply hole  27   b  for directing the ink out formed in the main body  27   a.    
     One side of the main body  27   a  protrudes from the vessel portion  31 , and an ink ejection port (not shown) formed at the other side thereof is located in the vessel portion  31 . A flat supply member welding portion  27   c  (see  FIG. 3 ) is adhered to the vessel portion  31  in a plane direction of the vessel portion  31 . 
     A seal member  32  is fitted into the front end of the main body  27   a  protruding from the vessel portion  31 . A supply hole  32   a  for directing the ink out is formed in the center of the seal member  32 . A spring washer  33  and a coil spring  34  are provided in the supply hole  27   b  of the main body  27   a  at the inside of the seal member  32 . 
     The coil spring  34  urges the spring washer  33  toward the seal member  32  such that the spring washer  33  closes the supply hole  32   a  of the seal member  32 . 
     When the ink cartridge  20  is provided in the cartridge mounting portion, an ink supply needle (not shown) provided at a predetermined position of the cartridge mounting portion passes through the seal member  32  in the supply member  27  and the spring washer  33  is forced toward the vessel portion  31  against an elastic force of the coil spring  34 . When the spring washer  33  is forced toward the vessel portion  31  and is separated from the seal member  32 , the ink in the vessel portion  31  flows out through a gap between the seal member  32  and the spring washer  33 . 
     As shown in  FIGS. 5 and 6 , the vessel portion  31  in which the supply member  27  is mounted includes a film F obtained by laminating a plurality of layers. The film F includes a gas barrier layer S 1  obtained by laminating a plurality of layers such as nylon or aluminum and a resin layer S 2  obtained by laminating a plurality of thermoplastic resin layers such as polypropylene or polyethylene. The resin layer S 2  is formed of a material which can be thermally adhered to the main body  27   a  of the supply member  27 . 
     As shown in  FIGS. 3 and 6 , the vessel portion  31  includes a first welding portion  37  formed by folding one film F into a tubular shape in a state in which the gas barrier layer S 1  is placed outside and thermally welding the inner surfaces (resin layers S 2 ) of both ends F 1  and F 2  to each other. 
     As denoted by a first hatched region X 1  of  FIG. 4 , the first welding portion  37  is provided in a longitudinal direction of the vessel portion  31  and is folded from a base end to overlap an adjacent film surface. The first welding portion  37  corresponds to a first sealing portion of the claims. 
     The vessel portion  31  includes a second welding portion for sealing one opening  31   a  (see  FIG. 3 ) having a tubular shape with the supply member  27  interposed therebetween and a third welding portion  39  for sealing the other opening  31   b  which is a bottom portion of the vessel portion  31 . 
     As denoted by a second hatched region X 2  of  FIG. 4 , the second welding portion  38  adheres the inner surfaces of the facing films at the side of the opening  31   a  of the vessel portion  31  and corresponds to the second sealing portion of the claims. 
     As denoted by a third hatched region X 3  of  FIG. 4 , the third welding portion  39  adheres the inner surfaces of the facing films at the side of the opening  31   b  of the vessel portion  31  and corresponds to the third sealing portion of the claims. 
     As shown in  FIG. 3 , both side surfaces of the vessel portion  31  have gore portions  36  formed by folding the film F before forming the second welding portion  38  and the third welding portion  39 . 
     The gore portions  36  are placed under tension in a thickness direction (an arrow direction Y) of the rectangular parallelepiped vessel portion  31  by a pair of mountain-shaped folding portions  41  and  42  folded at opposed side surfaces of the vessel portion  31  in a longitudinal direction and a valley-shaped folding portion  43  between the pair of mountain-shaped folding portions  41  and  42 . 
     The gore portions  36  are formed at positions which do not overlap the first welding portion  37  at the opposed side surfaces of the vessel portion  31 . 
     As shown in  FIG. 6 , the pair of mountain-shaped folding portions  41  and  42  configuring the gore sections  36  have mountain-shaped maintenance portions  45  for maintaining the state in which the inner surfaces of the facing films contact each other. 
     In the present embodiment, the mountain-shaped maintenance portions  45  are continuously formed over the entire length of the longitudinal direction of the vessel portion  31  by thermally welding the inner surfaces of the facing films to each other, as denoted by a fourth hatched region X 4  of  FIG. 4 . 
     In the present embodiment, at both ends of the longitudinal direction of the pair of mountain-shaped folding portions  41  and  42  configuring the gore portions  36 , as shown in  FIG. 4 , second mountain-shaped maintenance portions  47  are each formed in a triangular shape in which a contact area is gradually widened toward one end thereof. 
     The second mountain-shaped maintenance portions  47  are formed by thermally welding the inner surfaces of the facing films to each other in the triangular shape denoted by a fifth hatched region X 5  of  FIG. 4 , similar to the above-described mountain-shaped maintenance portions  45 . 
     Next, the method of manufacturing the liquid vessel will be described. 
     When the film F is formed in the tubular shape, as shown in  FIG. 6 , the gas barrier layer S 1  is heated by inserting both ends F 1  and F 2  into a crimping tool (not shown) in a state in which the film is bent in the tubular shape such that the gas barrier layer S 1  is placed outside. The resin layers S 2  of the ends F 1  and F 2  are melted by heating and the ends F 1  and F 2  are adhered to each other by solidifying the molten resin, thereby forming the first welding portion  37 . 
     The film F having the tubular shape is pressed in a mold (not shown) such that a plurality of folding lines (the pair of mountain-shaped folding portions  41  and  42  and the valley-shaped folding portion  43 ) configuring the gore section  36  are formed at the opposed side surfaces of the vessel portion  31  in the longitudinal direction. Accordingly, two gore portions  36  are formed in the film F having the tubular shape. 
     As shown in  FIG. 6 , the gore portions are formed to have a cross section having substantially an M shape. The first welding portion  37  is provided between the gore portions  36 . That is, the first welding portion  37  is provided at a position spaced apart from the gore portions  36 . 
     The edges of the mountain-shaped folding portions  41  and  42  formed as the gore portions  36  are inserted into the crimping tool and the contacted resin layers S 2  are adhered such that the mountain-shaped maintenance portions  45  are formed as shown in  FIG. 6 . 
     Next, in a state in which the seal member  32  of the supply member  27  protrudes from the vessel portion  31  and the supply member welding portion  27   c  located at an opposite side is inserted into the vessel portion  31 , the opening  31   a  of the film F having the tubular shape is pressed by the crimping tool in an arrow direction E of  FIG. 5  and is heated such that the opening  31   a  is thermally sealed. Accordingly, the second welding portion  38  shown as the second hatched region X 2  of  FIG. 4  is formed. 
     At this time, both sides of the vessel portion  31  are formed of four-layer films F as shown in  FIG. 6 . Both sides of the vessel portion  31  are inserted into the crimping tool having a contact region having a triangular shape and the film F is pressed in an arrow direction D and is heated, thereby forming the second mountain-shaped maintenance portions  47  shown as the fifth hatched region X 5  of  FIG. 4 . 
     The ink is filled in the vessel portion  31  through the other opening  31  at a time when one opening  31   a  of the film F is sealed. 
     After the ink is filled in the vessel portion  31 , the other opening  31   b  of the film F having the tubular shape is heated and sealed by the crimping tool to become the third welding portion  39 . Accordingly, the third welding portion  39  shown by the third hatched region X 3  of  FIG. 4  is formed. 
     The ink pack  24  sealed by the thermal welding is contained in the body casing  26  in a state in which the first welding portion  37  is placed downward and the supply member  27  passes through the support port  28  of the body casing  26 . The cover  25  is engaged with the body casing  26  in a state in which the above-described film is adhered to the partition wall  26   c , thereby sealing the body casing  26 . 
     In the above-described ink pack  24 , the ink is completely filled in the liquid containing portion  30  before use (at the time of completion of initial charge of the ink). Accordingly, as shown in  FIG. 8 , the gore portions  36  of the both side surfaces of the liquid containing portion  30  completely expand, but the pair of mountain-shaped folding portions  41  and  42  of the gore portions  36  are in a contact state at the time of folding by providing the mountain-shaped maintenance portions  45 . Accordingly, a folding property of the gore portions  36  is not impaired by the restoring force of the vessel portion  31 . Accordingly, when the liquid containing portion  30  is pressurized from the outside by pressurized air such that the ink in the liquid containing portion  30  is supplied from the supply member  27 , which is the liquid lead-out portion, to the inkjet recording apparatus and the amount of contained ink is reduced, the liquid containing portion is compressed according to the reduction of the amount of ink and thus the gore sections  36  are rapidly shrunken. 
     That is, the folding property of the gore portions  36  is not impaired even though the film used in the liquid containing portion  30  is made thicker in order to increase the amount of contained ink. In addition, since the liquid containing portion  30  is difficult to crush, the amount of residual ink can be reduced. 
     Since the liquid containing portion  30  is adequately crushed in accordance with the consumption of the ink contained in the liquid containing portion  30 , the amount of residual ink due to the deformation which occurs due to the crushing of the gore sections  36  is minimized and the printing cost of the inkjet recording apparatus can be reduced. 
     In the ink pack  24  according to the present embodiment, the mountain-shaped maintenance portions  45  are formed in the pair of mountain-shaped folding portions  41  and  42  configuring the gore portions  36  of the liquid containing portion  30 . The mountain-shaped maintenance portions  45  are formed by welding the inner surfaces of the facing films to each other. Accordingly, since a dedicated component is not required for forming the mountain-shaped maintenance portions  45 , the structure of the pair of mountain-shaped folding portions configuring the gore portions is simplified and thus process cost can be reduced. 
     In the ink pack  24  according to the present embodiment, at both ends of the longitudinal direction of the pair of mountain-shaped folding portions  41  and  42  configuring the gore portions  36 , the second mountain-shaped maintenance portions  47  for maintaining the state in which the inner surfaces of the facing films contact each other are each formed in a triangular shape in which a contact area is gradually widened toward one end thereof. 
     Accordingly, as shown in  FIG. 7 , since the ink is contained such that the volume is gradually reduced in the vicinity of both ends of the longitudinal direction of the liquid containing portion  30 , and the inner surfaces of the facing film contact each other at both ends of the longitudinal direction of the pair of mountain-shaped folding portions  41  and  42  configuring the gore portions  36 , the gore portions  36  are gradually folded from both ends of the longitudinal direction when the amount of liquid contained in the liquid containing portion  30  is reduced, such that an operation for folding the gore portions  36  is smoothly performed. 
     Although a configuration for forming the gore portions  36  at a position which does not overlap the first welding portion  37  is described in the first embodiment, the first welding portion  37  may be applied as one of the pair of mountain-shaped folding portions  41  and  42  of the gore portions  36 . In this case, the number of thermal welding processes is reduced to increase productivity and the first welding portion  37  is substantially removed from the surface of the vessel portion  31  to improve a design property. 
     In the liquid vessel according to the invention, the configuration of the mountain-shaped maintenance portions  45  of the pair of mountain-shaped folding portions  41  and  42  is not limited to the configuration in which the mountain-shaped maintenance portions  45  are continuously formed over the entire length of the longitudinal direction of the vessel portion  31  in the first embodiment. 
       FIG. 9  is a plan view of an ink pack of a liquid vessel according to a second embodiment of the invention. 
     In an ink pack  51  according to the second embodiment, the mountain-shaped maintenance portions  45  of the pair of mountain-shaped folding portions  41  and  42  (see  FIG. 3 ) of the liquid containing portion  30  are intermittently formed in the longitudinal direction of the mountain-shaped folding portions  41  and  42  at a predetermined interval. Since the mountain-shaped maintenance portions  45  can be formed by spot-welding the inner surfaces of the facing films, the workability of the mountain-shaped maintenance portions  45  can be improved and the productivity of the liquid containing portion  30  can be improved. Compared with the case where continuous welding is performed, the output of a welding device is suppressed and equipment cost and process cost can be reduced. 
     The predetermined interval is an interval which allows the contact state at the time of folding to be maintained in the mountain-shaped folding portions  41  and  42  of the gore sections  36  to prevent the folding property from being impaired when the gore portions  36  are folded in accordance with the consumption of ink. Alternatively, the mountain-shaped maintenance portions may be formed at places which are difficult to be folded at the time of compression according to the reduction of the amount of ink contained in the ink pack  51  as substantially a middle portion of the longitudinal direction of the mountain-shaped folding portions  41  and  42 . 
     The method of forming the mountain-shaped maintenance portions according to the invention is not limited to the thermal welding according to the above-described embodiment. 
       FIG. 10  is a cross-sectional view of main portions of an ink pack of a liquid vessel according to a third embodiment of the invention. 
     In an ink pack  53 , clips  55  are fitted to the pair of mountain-shaped folding portions  41  and  42  configuring the gore portions  36  in a state in which the inner surfaces of the facing films contact to each other and the clips  55  function as the mountain-shaped maintenance portions  45 . 
     Since the thermal welding is not used, it is possible to increase a freedom degree of the method of manufacturing the ink pack  53 . 
     Although the gore portion has the pair of mountain-shaped folding portions and the valley-shaped folding portion between the pair of mountain-shaped folding portions in the above-described embodiments, the invention is not limited to the configuration. The number of mountain-shaped folding portions may be more than three and the number of valley-shaped folding portions may be more than two (number of mountain-shaped folding portions−1). 
     Although the printer  11  for discharging the ink is described as a liquid ejecting apparatus in the embodiments, other liquid ejecting apparatuses may be used. For example, a liquid ejecting apparatus for ejecting liquid, an electrode material or a color material used in a printing apparatus including a facsimile machine or copier, a liquid crystal display, an electroluminescence (EL) display, or surface light-emitting display, a liquid ejecting apparatus for ejecting a bioorganic material used for manufacturing a bio chip, or an apparatus for ejecting a sample as a precise pipette may be used. The fluid (liquid) is not limited to ink and other fluid (liquid) may be used.