Patent Publication Number: US-2009237469-A1

Title: Liquid delivery system and manufacturing method for the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the priority based on Japanese Patent Application No. 2008-73324 filed on Mar. 21, 2008, the disclosure of which is hereby incorporated by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a liquid delivery system for delivering liquid to a liquid jetting device, and to a method of manufacturing the same. 
     2. Description of the Related Art 
     Ink-jet printers are an example of one known class of liquid jetting device. In an ink-jet printer, ink is delivered from one or more ink cartridges. In one known conventional technology, a large-capacity ink tank is provided outside of the ink-jet printer and is connected by a tube to an ink cartridge in the printer, thereby increasing the ink storage capacity. 
     However, depending on the type of ink cartridge, simply connecting a tube to the ink cartridge may result in loss of ink cartridge functionality, with a possibility that ink will not be delivered appropriately to the print head of the printer. This problem is not limited to ink-jet printers, but is a problem that is common generally to liquid jetting devices or liquid-consuming devices installable of liquid receptacles. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide technology for appropriate delivery of liquid to a liquid jetting device that accommodates installation of a liquid receptacle. 
     According to an aspect of the present invention, there is provided a method of manufacturing a liquid delivery system that delivers liquid to a liquid jetting device. The method includes the steps of: (a) providing a liquid receptacle that is installable on the liquid jetting device; (b) providing a liquid supply device for supplying the liquid receptacle with the liquid; and (c) connecting the liquid receptacle and the liquid supply device with a liquid flow passage member. The liquid receptacle may have a liquid storage chamber that stores liquid; a liquid delivery port that delivers the liquid to the liquid jetting device; an intermediate flow passage leading from the liquid storage chamber to the liquid delivery port; and a sensor, disposed in the intermediate flow passage, for sensing whether the liquid is present or not. The step (c) includes connecting the liquid flow passage member to the intermediate flow passage at a connection location downstream of the sensor. Typically, within the entire liquid flow passage, the flow passage resistance will be high at the location of the sensor which has been disposed in the intermediate flow passage. Consequently, if the liquid flow passage member is connected to the upstream side of the sensor, it is possible that replenishing liquid supplied from the liquid supply device to the liquid flow passage member will not be delivered sufficiently to the liquid jetting device, due to the high flow passage resistance at the sensor location. According to the above configuration on the other hand, because the liquid flow passage member is connected to the intermediate flow passage at a connection location downstream of the sensor, it is possible for replenishing liquid supplied from the liquid supply device via the liquid flow passage member to be delivered appropriately to the liquid jetting device. 
     The intermediate flow passage may have a buffer chamber located downstream of the sensor, and the liquid flow passage member may be connected to the buffer chamber. According to this configuration, the liquid flow passage member is connected to the buffer chamber of relatively large ink storage capacity, thus making connection relatively easy. 
     The intermediate flow passage may include: a differential pressure valve housing chamber, disposed downstream of the sensor, for housing a differential pressure valve that opens and closes responsive to a differential pressure arising through consumption of the liquid; and a vertical flow passage, disposed downstream of the differential pressure valve housing chamber, for leading the liquid to the liquid delivery port in the vertical direction. In this case, the liquid flow passage member may be connected to the vertical flow passage. According to this configuration, since the liquid flow passage member is connected to the vertical flow passage, even if air bubbles are introduced via the liquid flow passage member, the air bubbles will rise directly into the differential pressure valve chamber and become trapped there. Consequently, the likelihood of air bubbles being discharged into the liquid jetting device from the liquid delivery port situated below the vertical flow passage will be reduced. 
     The intermediate flow passage may include a liquid communication hole which is disposed downstream of the sensor and which is formed in a wall inside the liquid receptacle, and the liquid flow passage member may be connected to the liquid communication hole With this configuration, the liquid communication hole that has been formed in the wall of the liquid receptacle is utilized to connect the liquid flow passage member, thereby affording a simple connection procedure. 
     The liquid receptacle may further include an air flow passage that connects the liquid storage chamber to an outside air, and the step (c) may further include closing off the air flow passage at a location upstream of the connection location of the liquid flow passage member to the intermediate flow passage. With this configuration, air (air bubbles) will be prevented from flowing into the sensor via the air flow passage, and malfunction of the sensor will be prevented accordingly. 
     There are various possible modes of working the present invention, including but not limited to a liquid delivery system and a method of manufacturing the same; a liquid receptacle for use in a liquid delivery system and a method of manufacturing the same; and a liquid jetting device or a liquid consuming device, for example. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  show an example of an on-cartridge type ink-jet printer and an ink delivery system employing the same; 
         FIGS. 2A and 2B  show an example of an off-cartridge type ink-jet printer and an ink delivery system employing the same; 
         FIG. 3  is a first external perspective view of an ink cartridge; 
         FIG. 4  is a second external perspective view of an ink cartridge; 
         FIG. 5  is a first exploded perspective view of an ink cartridge; 
         FIG. 6  is a second exploded perspective view of an ink cartridge; 
         FIG. 7  is a drawing depicting an ink cartridge installed on a carriage; 
         FIG. 8  is a diagram depicting conceptually the pathway leading from an air vent hole to a liquid delivery port; 
         FIG. 9  is a drawing depicting a cartridge body from the front face side; 
         FIG. 10  is a drawing depicting a cartridge body from the back face side. 
         FIGS. 11A and 11B  are diagrams of  FIG. 9  and  FIG. 10  in simplified form; 
         FIG. 12  illustrates an ink cartridge in the initial ink-filled condition; 
         FIGS. 13A and 13B  illustrate the flow of ink within an ink cartridge; 
         FIGS. 14A and 14B  show the A-A cross section of  FIG. 13A ; 
         FIGS. 15A and 15B  illustrate flow of air within an ink cartridge; 
         FIGS. 16A and 16B  illustrate a method of connecting an ink supply tube to an ink cartridge in Embodiment 1; 
         FIG. 17  is a conceptual depiction of an ink delivery system pathway in Embodiment 1; 
         FIGS. 18A and 18B  illustrate modified examples of Embodiment 1; 
         FIGS. 19A and 19B  illustrate a method of connecting an ink supply tube to an ink cartridge in Embodiment 2; 
         FIG. 20  is a drawing depicting the A-A cross section of  FIG. 19A ; 
         FIG. 21  is a conceptual depiction of an ink delivery system pathway in Embodiment 2; 
         FIGS. 22A and 22B  illustrate a method of connecting an ink supply tube to an ink cartridge in Embodiment 3; 
         FIG. 23  is a drawing depicting the A-A cross section of  FIG. 22A ; and 
         FIG. 24  is a conceptual depiction of an ink delivery system pathway in Embodiment 3. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The embodiments of the present invention will be described in the order indicated below. 
     A. Overall Configuration of Ink Delivery System 
     B. Basic Configuration of Ink Cartridge 
     C. Configuration of Ink Cartridge for Use in Ink Delivery System and Method of Manufacturing the Same 
     D. Modified Examples 
     A. OVERALL CONFIGURATION OF INK DELIVERY SYSTEM  
       FIG. 1A  is a perspective view depicting an exemplary ink-jet printer. This ink-jet printer  1000  has a carriage  200  that travels in the main scanning direction, as well as a feed mechanism for feeding printing paper PP in the sub-scanning direction. A print head (not shown) is disposed at the lower end of the carriage  200 , and this print head is used to carry out printing on the printing paper PP. A cartridge housing capable of accommodating multiple ink cartridges  1  is provided on the carriage  200 . This kind of printer, in which the ink cartridges are installed on the carriage, is termed an “on-carriage type printer.” 
       FIG. 1B  depicts an ink delivery system that employs this ink-jet printer  1000 . In this system, large-capacity ink tank  900  is provided externally to the ink-jet printer  1000 , with the large-capacity ink tank  900  and the ink cartridges  1  being connected by ink supply tubes  910 . The large-capacity ink tank  900  contains ink receptacles equal in number to the number of ink cartridges  1 . By providing this additional large-capacity ink tank  900 , the ink storage capacity of the printer can be substantially increased appreciably. The large-capacity ink tank  900  is also referred to as an “external ink tank.” 
       FIG. 2A  is a perspective view depicting another exemplary ink-jet printer. In this ink-jet printer  1110 , the ink cartridges are not installed on the carriage  1200 , but rather are disposed in a cartridge housing  1120  to the outside of the printer chassis (to the outside of the range of travel of the carriage). The ink cartridges  1  and the carriage  1200  are connected by ink delivery tubes  1210 . This kind of printer, in which the ink cartridges are installed at a location other than the carriage, is termed an “off-carriage type printer.” 
       FIG. 2B  depicts an ink delivery system that employs this ink-jet printer  1100 . In this system, an additional large-capacity ink tank  900  is provided, and the large-capacity ink tank  900  and the ink cartridges  1  are connected by ink supply tubes  910 . Thus, for this type of off-carriage printer as well, by the same method as with the on-carriage type printer it will be possible to design an ink delivery system having appreciably larger ink storage capacity. 
     Herein the system composed of the ink cartridges  1 , the large-capacity ink tank  900 , and the ink supply tubes  910  will be referred to as the “ink delivery system.” In some instances, the entire system inclusive of the ink-jet printer will be referred to as the “ink delivery system.” 
     Following is a description first of the design of the ink cartridges that are utilized in the embodiments of the ink delivery system herein; followed by a description of the detailed configuration of the ink delivery system and of a method for manufacturing it. While the following description relates for the most part to the use of an on-carriage type printer, the specifics thereof are applicable analogously to an ink-jet printer of off-carriage type. 
     B. BASIC CONFIGURATION OF INK CARTRIDGE  
       FIG. 3  is a first external perspective view of an ink cartridge.  FIG. 4  is a second external perspective view of an ink cartridge.  FIG. 4  depicts the cartridge of  FIG. 3  viewed from the opposite direction.  FIG. 5  is a first exploded perspective view of an ink cartridge.  FIG. 6  is a second exploded perspective view of an ink cartridge.  FIG. 6  depicts the cartridge of  FIG. 5  viewed from the opposite direction.  FIG. 7  depicts an ink cartridge installed in the carriage  200 . In  FIGS. 3 to 6 , the X, Y, and Z axes are shown in order to identify direction. 
     The ink cartridge  1  stores liquid ink inside. As depicted in  FIG. 7 , the ink cartridge  1  is installed on the carriage  200  of the ink-jet printer, and delivers ink to the print head of the ink-jet printer. 
     As depicted in  FIGS. 3 and 4 , the ink cartridge  1  has generally rectangular parallelepiped contours, and has a Z-axis positive direction face  1   a , a Z-axis negative direction face  1   b,  an X-axis positive direction face  1   c,  an X-axis negative direction face  1   d,  a Y-axis positive direction face  1   e,  and a Y-axis negative direction face  1   f.  For convenience, hereinbelow face  1   a  will be termed the top face, face  1   b  the bottom face, face  1   c  the right face, face  1   d  the left face, face  1   e  the front face, and face  1   f  the back face. The sides on which these faces  1   a  to  1   f  are located will be respectively termed the top face side, the bottom face side, the right face side, the left face side, the front face side, and the back face side. 
     On the bottom face  1   b  there is disposed a liquid delivery port  50  having a delivery hole for delivering ink to the ink-jet printer. Also, an air vent hole  100  for introducing air into the ink cartridge  1  opens onto the bottom face  1   b  ( FIG. 6 ). 
     The air vent hole  100  has a depth and diameter such that a projection  230  ( FIG. 7 ) that has been formed on the carriage  200  of the ink-jet printer will fit within it, with enough latitude to have a prescribed gap. The user will peel off a sealing film  90  that airtightly seals the air vent hole  100 , then install the ink cartridge  1  on the carriage  200 . The projection  230  is provided in order to prevent the user from forgetting to peel off the sealing film  90 . 
     As depicted in  FIGS. 3 and 4 , a locking lever  11  is disposed on the left face  1   d.  A projection  11   a  is formed on the locking lever  11 . During installation on the carriage  200 , the projection  11   a  will lock in a recess  210  that has been formed on the carriage  200 , thereby securing the ink cartridge  1  to the carriage  200  ( FIG. 7 ). As will be appreciated from the above, the carriage  200  constitutes an installation portion on which the ink cartridges  1  are installed. During printing by the ink-jet printer, the carriage  200 , in unison with the print head (not shown), undergoes reciprocating motion across the width of the printing medium in the main scanning direction. The main scanning direction is indicated by arrow ARI in  FIG. 7 . Specifically, when the ink-jet printer carries out printing the ink cartridges  1  will be undergo reciprocating motion in the Y direction in the drawings. 
     A circuit board  34  is disposed to the lower side of the locking lever  11  on the left face id ( FIG. 4 ). Several electric terminals  34  have been formed on the circuit board  34 ; these electric terminals  34  electrically connect to the ink-jet printer via electric terminal pins (not shown) provided on the carriage  200 . 
     An outer surface film  60  is adhered to the top face  1   a  and the back face if of the ink cartridge  1 . 
     The internal configuration and configuration of parts of the ink cartridge  1  will be described with reference to  FIGS. 5 and 6 . The ink cartridge  1  has a cartridge body  10 , and a cover member  20  covering the front face side of the cartridge body  10 . 
     Ribs  10   a  of various shapes have been formed on the front face side of the cartridge body  10  ( FIG. 5 ). A film  80  that covers the front face side of the cartridge body  10  is positioned between the cartridge body  10  and the cover member  20 . The film  80  is adhered carefully to the edge faces on the front face side of the ribs  10   a  of the cartridge body  10  so as to prevent gaps from forming. The ribs  10   a  and the film  80  serve to divide the interior of the ink cartridge  1  into a plurality of small chambers, for example, ink storage chambers and a buffer chamber. These chambers will be discussed in more detail later. 
     A differential pressure valve housing chamber  40   a  and a vapor-liquid separation chamber  70   a  are formed to the back face side of the cartridge body  10  ( FIG. 6 ). The differential pressure valve housing chamber  40   a  houses a differential pressure valve  40 , which includes a valve member  41 , a spring  42 , and a spring seat  43 . A ledge  70   b  is formed on the inner wall that encloses the bottom face of the vapor-liquid separation chamber  70   a , and a vapor-liquid separation membrane  71  is adhered to the ledge  70   b;  this arrangement in its entirety constitutes a vapor-liquid separation filter  70 . 
     A plurality of grooves  10   b  are also formed to the back face side of the cartridge body  10  ( FIG. 6 ). When the outer surface film  60  is disposed so as to cover substantially the entire back face side of the cartridge body  10 , these grooves  10   b  will define various flow passages (discussed later) between the cartridge body  10  and the outer surface film  60 , for example, flow channels through which ink and air may flow. 
     Next, the arrangement in the vicinity of the circuit board  34  mentioned earlier will be described. A sensor housing chamber  30   a  is formed to the lower face side of the right face of the cartridge body  10  ( FIG. 6 ). The sensor housing chamber  30   a  houses a liquid level sensor  31  and a fastening spring  32 . The fastening spring  32  fastens the liquid level sensor  31  by pushing it against the inside wall on the lower face side of the sensor housing chamber  30 . An opening on the right face side of the sensor housing chamber  30  is covered by a cover member  33 , and the circuit board  34  mentioned earlier is fastened to the outside face  33   a  of the cover member  33 . The sensor housing chamber  30   a , the liquid level sensor  31 , the fastening spring  32 , the circuit board  34 , and a sensor flow passage forming chamber  30   b , discussed later, will be referred to as the sensor section  30 . 
     While not illustrated in detail, the liquid level sensor  31  includes a cavity that defines part of the intermediate flow passage (to be discussed later); an oscillating plate that defines part of the wall of the cavity; and a piezoelectric element arranged on the oscillating plate. The terminals of the piezoelectric element are connected electrically to some of the electric terminals of the circuit board  34 ; and with the ink cartridge  1  installed in the ink-jet printer, the terminals of the piezoelectric element will be electrically connected to the ink-jet printer via electric terminals of the circuit board  34 . By applying electrical energy to the piezoelectric element, the ink-jet printer can induce oscillation of the oscillating plate through the agency of the piezoelectric element. The presence of any air bubbles in the cavity will be ascertained through subsequent detection, through the agency of the piezoelectric element, of a characteristic (frequency etc.) of residual vibration of the oscillating plate. Specifically, when due to consumption of the ink stored in the cartridge body  10 , the state inside the cavity changes from an ink-filled state to an air-filled state, there will be a change in the characteristics of residual vibration of the oscillating plate. By detecting this change in characteristics of residual vibration via the liquid level sensor  31 , the ink-jet printer detects whether ink is present in the cavity. 
     The circuit board  34  is provided with a rewritable nonvolatile memory such as EEPROM (Electronically Erasable and Programmable Read Only Memory), which is used to store parameters such as the amount of ink consumed by the ink-jet printer. 
     On the bottom face side of the cartridge body  10  there are disposed the liquid delivery port  50  and the air vent hole  100  mentioned previously, as well as a depressurization hole  110 , a sensor flow passage forming chamber  30   b , and a labyrinthine passage forming chamber  95   a  ( FIG. 6 ). The depressurization hole  110  is utilized during injection of the ink in the ink cartridge  1  manufacturing process, in order to suck out air and depressurize the interior of the ink cartridge  1 . The sensor flow passage forming chamber  30   b  and the labyrinthine passage forming chamber  95   a  constitute parts of the intermediate flow passage, discussed later. The sensor flow passage forming chamber  30   b  and the labyrinthine passage forming chamber  95   a  are the sections that are narrowest and have the highest flow resistance in the intermediate flow passage. In particular, the labyrinthine passage forming chamber  95  defines a flow passage of labyrinthine configuration, and produces a meniscus (a liquid bridge that forms in the flow passage), and therefore the flow resistance is particularly high in this section. 
     The openings of the liquid delivery port  50 , the air vent hole  100 , the depressurization hole  110 , the labyrinthine passage forming chamber  95   a , and the sensor flow passage forming chamber  30   b  will be respectively sealed off by sealing films  54 ,  90 ,  98 ,  95 ,  35  upon completion of manufacture of the ink cartridge  1 . Of these, the sealing film  90  is intended to be peeled off by the user prior to installing the ink cartridge  1  in the carriage  200  as described earlier. By so doing, the air vent hole  100  will communicate with the outside, allowing air to be introduced into interior of the ink cartridge  1 . The sealing film  54  is designed to be ruptured by an ink delivery needle  240  provided on the carriage  200  when the ink cartridge  1  is installed in the carriage  200  of the ink-jet printer. 
     In the interior of the liquid delivery port  50  are housed, in order from the lower face side, a seal member  51 , a spring seat  52 , and a blocking spring  53 . When the ink delivery needle  240  has been inserted into the liquid delivery port  50 , the seal member  51  will function to seal the gap between the inside wall of the liquid delivery port  50  and the outside wall of the ink delivery needle  240 . The spring seat  52  is adapted to contact the inside wall of the seal member  51  and block off the liquid delivery port  50  when the ink cartridge  1  is not installed in the carriage  200 . The blocking spring  53  is adapted to urge the spring seat  52  in the direction of contact with the inside wall of the seal member  51 . When the ink delivery needle  240  is inserted into the liquid delivery port  50 , the upper end of the ink delivery needle  240  will push up the spring seat  52  and create a gap between the spring seat  52  and the seal member  51  so that ink is delivered to the ink delivery needle  240  through this gap. 
     Next, before proceeding to a more detailed description of the internal structure of the ink cartridge  1 , for purposes of aiding understanding, the pathway leading from the air vent hole  100  to the liquid delivery port  50  will be described in conceptual terms with reference to  FIG. 8 .  FIG. 8  is a diagram depicting conceptually the pathway leading from the air vent hole to the liquid delivery port. 
     The pathway leading from the air vent hole  100  to the liquid delivery port  50  will be broadly divided into ink storage chambers for holding ink, an air flow passage situated on the upstream side of the ink storage chambers, and an intermediate flow passage situated on the downstream side of the ink storage chambers. 
     The ink storage chambers include, in order from the upstream side, a first ink holding chamber  370 , a holding chamber connector passage  380 , and a second ink holding chamber  390 . The upstream end of the holding chamber connector passage  380  communicates with the first ink holding chamber  370 , while the downstream end of the holding chamber connector passage  380  communicates with the second ink holding chamber  390 . 
     The air flow passage includes, in order from the upstream side, a serpentine passage  310 , a vapor-liquid separation chamber  70   a  that houses the vapor-liquid separation membrane  71  discussed earlier, and connecting paths  320  to  360  that connect the vapor-liquid separation chamber  70   a  with the ink storage chamber. The serpentine passage  310  communicates at its upstream end with the air vent hole  100 , and at its downstream end with the vapor-liquid separation chamber  70   a.  The serpentine passage  310  is elongated and extends in a sinuous configuration so as to maximize the distance from the air vent hole  100  to the first ink holding chamber  370 . Through this arrangement, evaporation of moisture from the ink inside the ink storage chambers will be kept to a minimum. The vapor-liquid separation membrane  71  is constructed of material that permits vapor to pass, but does not allow liquid to pass. By situating the vapor-liquid separation membrane  71  between the upstream end and the downstream end of the vapor-liquid separation chamber  70   a , ink backflowing from the ink storage chambers will be prevented from advancing upstream beyond the vapor-liquid separation chamber  70   a.  The specific configuration of the connecting paths  320  to  360  will be discussed later. 
     The intermediate flow passage includes, in order from the upstream side, a labyrinthine flow passage  400 , a first flow passage  410 , the aforementioned sensor section  30 , a second flow passage  420 , a buffer chamber  430 , the aforementioned differential pressure valve housing chamber  40   a  housing the differential pressure valve  40 , and third flow passages  450 ,  460 . The labyrinthine flow passage  400  has a three-dimensional labyrinthine configuration and includes the space defined by the aforementioned labyrinthine passage forming chamber  95   a.  Through the labyrinthine flow passage  400 , air bubbles entrained in the ink will be trapped so as to prevent air bubbles from being entrained in the ink downstream from the labyrinthine flow passage  400 . The labyrinthine flow passage  400  is also termed an “air bubble trap flow passage.” The first flow passage  410  communicates at its upstream end with the labyrinthine flow passage  400 , and communicates at its downstream end with the sensor flow passage forming chamber  30   b  of the sensor section  30 . The second flow passage  420  communicates at its upstream end with the sensor flow passage forming chamber  30   b  of the sensor section  30 , and at its downstream end with the buffer chamber  430 . The buffer chamber  430  communicates directly with the differential pressure valve housing chamber  40   a  with no intervening flow passage. Thus, the space from the buffer chamber  430  to the liquid delivery port  50  is minimized, and the likelihood of ink accumulating and settling out in that space will be reduced. In the differential pressure valve housing chamber  40   a , through the action of the differential pressure valve  40 , the pressure of the ink to the downstream side of the differential pressure valve housing chamber  40   a  will be maintained to be lower than the ink pressure on the upstream side, so that the ink in the downstream side assumes negative pressure. The third flow passages  450 ,  460  (see  FIG. 9 ) communicate at the upstream side with the differential pressure valve housing chamber  40   a  and at the downstream side with the liquid delivery port  50 . These third flow passages  450 ,  460  define vertical flow passages through which ink exiting the differential pressure valve housing chamber  40   a  will be guided vertically downward and into the liquid delivery port  50 . 
     At the time of manufacture of the ink cartridge  1 , the cartridge will be filled up to the first ink holding chamber  370 , as indicated by the liquid level depicted conceptually by the broken line ML 1  in  FIG. 8 . In the absence of an additional large-capacity ink tank  900  ( FIGS. 1A ,  1 B,  2 A,  2 B), as the ink inside the ink cartridge  1  is consumed by the ink-jet printer the liquid level will move towards the downstream end and it will be replaced by air flowing into the ink cartridge  1  from the upstream end through the air vent hole  100 . As ink consumption progresses, the liquid level will reach the sensor section  30  indicated by the liquid level depicted conceptually by the broken line ML 2  in  FIG. 8 . At this point, air will enter the sensor section  30 , and ink depletion will be detected by the liquid level sensor  31 . Once ink depletion has been detected, the ink jet printer will halt printing and alert the user at a stage before the ink present to the downstream side of the sensor section  30  (in the buffer chamber  430  etc.) is completely consumed. This is because if the ink is totally depleted, when it is attempted to continue further printing there is a risk that air may be drawn into the print head and cause problems. 
     The specific configuration of each element on the pathway from the air vent hole  100  to the liquid delivery port  50  within the ink cartridge  1  will be described with reference to  FIGS. 9 to 11B .  FIG. 9  is a drawing depicting the cartridge body  10  from the front face side.  FIG. 10  is a drawing depicting the cartridge body  10  from the back face side.  FIG. 11A  is a model diagram of  FIG. 9  in simplified form.  FIG. 11B  is a model diagram of  FIG. 10  in simplified form. 
     In the ink storage chambers, the first ink holding chamber  370  and the second ink holding chamber  390  are formed on the front face side of the cartridge body  10 . In  FIG. 9  and  FIG. 11A , the first ink holding chamber  370  and the second ink holding chamber  390  are shown respectively by single hatching and crosshatching. The holding chamber connector passage  380  is formed on the back face side of the cartridge body  10 , at the location shown in  FIG. 10  and  FIG. 11B . A communication hole  371  is provided to connect the upstream end of the holding chamber connector passage  380  with the first ink holding chamber  370 , and a communication hole  391  is provided to connect the downstream end of the holding chamber connector passage  380  with the second ink holding chamber  390 . 
     In the air flow passage, the serpentine passage  310  and the vapor-liquid separation chamber  70   a  are formed on the back face side of the cartridge body  10 , at the respective locations shown in  FIG. 10  and  FIG. 11B . A communication hole  102  is provided to connect the upstream end of the serpentine passage  310  with the air vent hole  100 . The downstream end of the serpentine passage  310  passes through the side wall of the vapor-liquid separation chamber  70   a  and communicates with the vapor-liquid separation chamber  70   a.    
     Turning now to a more detailed description of the connecting paths  320  to  360  of the air flow passage depicted in  FIG. 8 , these are composed of a first space  320 , a third space  340 , and a fourth space  350  situated on the front face side of the cartridge body  10  (see  FIG. 9  and  FIG. 11A ), and a second space  330  and a fifth space  360  situated on the back face side of the cartridge body  10  (see  FIG. 10  and  FIG. 11B ), these spaces being situated in-line, in order of their assigned symbols from the upstream end, to define a single flow passage. A communication hole  322  is provided to connect the vapor-liquid separation chamber  70   a  to the first space  320 . Communication holes  321 ,  341  are provided to connect the first space  320  with the second space  330 , and the second space  330  with the third space  340 , respectively. The third space  340  and the fourth space  350  communicate with one another through a notch  342  that has been formed in the rib separating the third space  340  and the fourth space  350 . Communication holes  351 ,  372  are provided to connect the fourth space  350  with the fifth space  360 , and the fifth space  360  with the first ink holding chamber  370 , respectively. 
     In the intermediate flow passage, the labyrinthine flow passage  400  and the first flow passage  410  are formed on the front face side of the cartridge body  10  at the respective locations shown in  FIG. 9  and  FIG. 11A . A communication hole  311  is provided in the rib that separates the second ink holding chamber  390  from the labyrinthine flow passage  400 , and connects the second ink holding chamber  390  with the labyrinthine flow passage  400 . As discussed previously with reference to  FIG. 6 , the sensor section  30  is situated on the lower face side of the right face of the cartridge body  10  ( FIGS. 9 to 11B ). The second flow passage  420  and the aforementioned vapor-liquid separation chamber  70   a  are formed on the back face side of the cartridge body  10  at the respective locations shown in  FIG. 10  and  FIG. 11B . The buffer chamber  430  and the third flow passage  450  are formed on the front face side of the cartridge body  10  at the respective locations shown in  FIG. 9  and  FIG. 11A . A communication hole  312  is provided to connect the labyrinthine passage forming chamber  95   a  ( FIG. 6 ) of the sensor section  30  with the second flow passage  420 ; and a communication hole  431  is provided to connect the downstream end of the second flow passage  420  with the buffer chamber  430 . A communication hole  432  is provided to directly connect the buffer chamber  430  with the differential pressure valve housing chamber  40   a . Communication holes  451 , 452  are provided to respectively connect the differential pressure valve housing chamber  40   a  with the third flow passage  450 , and the third flow passage  450  with the ink delivery hole inside the liquid delivery port  50 . As mentioned earlier, in the intermediate flow passage, the labyrinthine flow passage  400  and the sensor section  30  (the labyrinthine passage forming chamber  95   a  and the sensor flow passage forming chamber  30   b  of  FIG. 5 ) are the sections of the flow passage in which flow resistance is highest. 
     A space  501  shown in  FIG. 9  and  FIG. 11A  is an unfilled space that is not filled with ink. The unfilled space  501  is not situated on the pathway leading from the air vent hole  100  to the liquid delivery port  50 , but is rather independent. An outside air communication hole  502  that communicates with the outside air is formed on the back face side of the unfilled space  501 . The unfilled space  501  serves as a degassing space that is brought to negative pressure when the ink cartridge  1  is packaged in a vacuum pack. Thus, as long as the ink cartridge  1  is kept in the package, the inside pressure of the cartridge body  10  will be maintained below a prescribed pressure value so that the cartridge can deliver ink with negligible dissolved air. 
       FIG. 12  is an illustration depicting an ink cartridge in the initial ink-filled condition (factory condition). Here, the film  80  is shown joined along the wall edges indicated by the heavy solid line, and also joined on the other inner wall edges; the ink is held inside of these walls. A liquid level ML 1  is shown here, and the section containing the ink IK is indicated by hatching. Specifically, of the ink storage chambers  370 ,  380 ,  390  (see  FIG. 8 ), the liquid level ML 1  will be situated in the upper part of the first ink holding chamber  370  which lies furthest towards the upstream end, with air being present above this level. Typically, as the ink in the cartridge is consumed, this liquid level ML 1  will gradually drop. However, once the additional large-capacity ink tank  900  ( FIGS. 1B ,  2 B) has been installed, there will be no change in liquid level in the ink cartridge. 
       FIGS. 13A and 13B  illustrate the flow of ink within an ink cartridge. Here, the ink flow path from the first ink holding chamber  370  to the liquid delivery port  50  is shown by thick solid lines and broken lines. This ink flow path can be understood as a more detailed rendering of the path through the ink storage chamber and the intermediate flow passage depicted in  FIG. 8 . 
       FIGS. 14A and 14B  show the A-A cross section of  FIG. 13A . The drawings depict the section that includes the differential pressure valve  40 , the buffer chamber  430  at the upstream side of the differential pressure valve  40 , and the vertical passages  450 ,  460  at the downstream side of the differential pressure valve  40 . For convenience in illustration, the communication hole  432  that connects the buffer chamber  430  with the differential pressure valve chamber  40   a  is depicted as being at a location somewhat further towards the upper side than in  FIG. 13A .  FIG. 14A  depicts the differential pressure valve  40  in the closed state. As the ink head consumes ink, the pressure on the liquid delivery port  50  side will drop and the differential pressure valve  40  will assume the open state as depicted in  FIG. 14B . Once the differential pressure valve  40  opens, ink IK will flow from the buffer chamber  430  into the differential pressure valve housing chamber  40 a through the communication hole  432 , and thence through the vertical passages  450 ,  460  so that the ink IK is delivered from the liquid delivery port  50  to the print head. Utilizing the differential pressure valve  40 , the delivery pressure of ink delivered to the print head will be maintained within an appropriate pressure range, whereby it is possible for ejection of ink from the print head to take place under stable conditions. As will be understood from the preceding discussion, the buffer chamber  430  is disposed to the immediate front of the differential pressure valve  40 , and functions as a chamber for storing ink to be introduced into the differential pressure valve  40 . 
       FIGS. 15A and 15B  illustrate the flow of air within an ink cartridge. Here, the pathway of air flow from the air vent hole  100  ( FIG. 15B ) to the first ink holding chamber  370  is shown by thick solid lines and broken lines. This pathway of air flow can be understood as a more detailed rendering of the air flow path depicted in  FIG. 8 . 
     The discussion now turns to a method of manufacturing an ink delivery system ( FIG. 1B ,  FIG. 2B ) that employs the ink cartridge described above. 
     C. CONFIGURATION OF INK CARTRIDGE FOR USE IN INK DELIVERY SYSTEM AND METHOD  OF MANUFACTURING THE SAME  
       FIGS. 16A and 16B  show a method of connecting an ink supply tube  910  to an ink cartridge in Embodiment 1. The ink supply tube  910  as a liquid flow passage member is passed through the top face  1   a  of the cartridge, the wall  370   w  in the upper part of the first ink holding chamber  370 , and the wall  430   w  of the buffer chamber  430 , so as to connect with and open into the buffer chamber  430 . Ink supplied from the large-capacity ink tank  900  ( FIG. 1B ) will be introduced directly into the buffer chamber  430 . In preferred practice the ink supply tube  910  will be made of flexible material. 
     The tube  910  connection operation is carried out by a procedure such as the following, for example. First, the ink cartridge and the tube  910  are prepared. The ink cartridge depicted in  FIGS. 3 to 15A  and various other cartridges are acceptable for this purpose. As depicted in  FIG. 12 , prior to connecting the tube  910 , the ink holding chambers  370 ,  390  and the buffer chamber  430  of the cartridge are sealed by the film  80 , with the cover member  20  sandwiching it from the outside (see  FIG. 5 ). At this point, first, the cover member  20  will be detached, the film  80  will be partly or entirely peeled away, and holes will be made in the wall faces  1   a,    370   w,  and  430   w  respectively. If the tube  910  is to be connected to the location shown in  FIGS. 16A and 16B , it will be sufficient to peel off the section of the film  80  covering the first ink holding chamber  370 , as it is possible to carry out the process without peeling the sections of the film  80  that cover the other chambers (the buffer chamber  430  and the second ink holding chamber  390 ). The tube  910  is then passed through the holes in the wall faces  1   a,    370   w,  and  430   w  and fastened there. Fastening may be accomplished, for example, by applying an adhesive to the section of the tube  910  that will be pushed through the wall face  430   w  of the buffer chamber  430 . This fastening operation will also effect sealing together of the tube  910  and the wall face  430   w  of the buffer chamber  430 . Sealing together of the tube  910  with the other two wall faces la,  370   w  is optional. The communicating hole  311  that was made in the wall separating the second ink holding chamber  390  and the labyrinthine flow passage  400  is then closed off by injecting a filler material into it. Injection of this filler material may be carried out using a tool such as an injection syringe, and may be carried out through the film  80 . The reason for closing off the communicating hole  311  is to prevent outside air (air bubbles) from being introduced through the air vent hole  100  (see  FIG. 15B ) from flowing into the sensor section  30 , possibly causing the sensor section  30  to malfunction. The peeled section of the film  80  is then reattached, the ink is replenished if necessary, and the cover part  20  is then attached. This series of operations completes the operation to connect the tube to the ink cartridge. By then connecting the tube  910  to the large-capacity ink tank  900 , the ink delivery system is complete. 
       FIG. 17  is a conceptual depiction of the ink delivery system pathway in Embodiment 1. The large-capacity ink tank  900  has been connected to the buffer chamber  430  via the tube  910  so that ink may be delivered directly to the buffer chamber  430 . Typically, the large-capacity ink tank  900  will be provided with an air vent hole  902  as well so that air may be introduced into the large-capacity ink tank  900  in association with declining ink level. Consequently, it will be possible for ink to be fed to the buffer chamber  430  from the large-capacity ink tank  900  at a suitable pressure level at all times. 
     It should be noted that the location of the buffer chamber  430 , at the downstream side of the ink flow passages with high flow passage resistance (i.e. the labyrinthine flow passage  400  and the sensor section  30 ), has the advantage that the ink supplied from the large-capacity ink tank  900  need not pass through these ink flow passages  400 ,  30 . If the tube  910  is connected upstream from the ink flow passages  400 ,  30  of high flow passage resistance, the flow passage resistance from the large-capacity ink tank  900  to the tube  910  will be compounded by the flow passage resistance of these ink flow passages  400 ,  30 , with the possibility that sufficient ink may not be delivered to the print head. That is, as taught in the present embodiment, by connecting the tube  910  to the buffer chamber  430  on the downstream side of the sensor section  30 , it will be possible for ink to be delivered to the print head at appropriate pressure. In this regard, it is possible for the tube  910  to be connected to any flow passage that is situated on the downstream side from the sensor section  30 . 
     It should be also noted that the buffer chamber  430  is present to the upstream side of the differential pressure valve housing chamber  40   a  that houses the differential pressure valve  40 . Consequently, it will be possible for ink supplied through the tube  910  to be delivered to the print head at stable pressure conditions, by utilizing the function of the differential pressure valve  40 . 
     It should be further noted that in Embodiment 1, the communication hole  311  between the second ink holding chamber  390  and the labyrinthine flow passage  400  is closed off. As a result, air will be prevented from flowing into the sensor section  30  from the air vent hole  100 . By so doing, it will be possible to avoid situations where inflowing air causes the sensor section  30  to mistakenly sense that no ink is present. It is possible for this closing off of the ink flow passage to be made at any location to the upstream side of the tube  910  connection site. 
     According to Embodiment 1, because the ink supply tube  910  is connected to the downstream side of the sensor section  30 , the ink supplied from the tube  910  will be delivered to the print head of the printer without passing through the sensor section  30  which represents an ink flow passage with high flow passage resistance. It is accordingly possible to achieve stable ink delivery. 
       FIGS. 18A and 18B  show modified examples of Embodiment 1. In a first modified example depicted in  FIG. 18A , the tube  910  is passed through the right face  1   c  of the cartridge, the wall face  350   w  of the space  350  serving as an ink trap, and the wall face  370   ww  on the right side of the first ink holding chamber  370 , and is pushed through the wall face  430   w  of the buffer chamber  430 . In a second modified example depicted in  FIG. 18B , the tube  910  is passed through the left face  1   d  of the cartridge and the left wall face  350   sw  of the first ink holding chamber  370 , and is pushed through the wall face  430   w  of the buffer chamber  430 . These modified examples share with the preceding Embodiment 1 the feature that ink is supplied directly to the buffer chamber  430  via the tube  910 . Consequently, these modified examples afford advantages comparable to Embodiment 1. 
       FIGS. 19A and 19B  show a method of connecting an ink supply tube  910  to an ink cartridge in Embodiment 2. The ink supply tube  910  is passed through the top face  1   a  of the cartridge, the wall  370   w  in the upper part of the first ink holding chamber  370 , the wall  430   w  of the buffer chamber  430 , and the wall  390   w  between the buffer chamber  430  and the second ink holding chamber  390 , so as to connect with the vertical flow passage  460 . Consequently, ink supplied from the large-capacity ink tank  900  will be introduced directly into the vertical flow passage  460 . Sealing of the zones between the tube  910  and the wall faces  1   a,    370   w ,  390   w  is optional. 
       FIG. 20  is a drawing depicting the A-A cross section of  FIG. 19A . The tube  910  is affixed with adhesive or the like in an opening  460 h provided to the vertical flow passage  460 . Consequently, ink supplied from the tube  910  will be directly conducted vertically downward from the vertical flow passage  460  and delivered to the print head of the printer via the liquid delivery port  50 . In this example, the communication hole  432  connecting the buffer chamber  430  and the differential pressure valve  40  is closed off. In  FIG. 20 , for convenience in illustration, the communication hole  432  is depicted as being at a location somewhat further towards the upper side than in  FIGS. 13A ,  13 B. The tube  910  is depicted in its condition prior to being installed within the cartridge. 
       FIG. 21  is a conceptual depiction of the ink delivery system pathway in Embodiment 2. The large-capacity ink tank  900  has been connected to the vertical flow passage  460  via the tube  910  so that ink may be delivered directly to the vertical flow passage  460 . Consequently, as ink is consumed by the printer, it will be possible for ink from the large-capacity ink tank  900  to be delivered commensurately to the print head of the printer via the vertical flow passage  460  and the liquid delivery port  50 . 
     In Embodiment 2, as in Embodiment 1, it is preferable to prevent air from flowing into the sensor section  30  from the air vent hole  100 . This is the reason for closing off the communication hole  432  which is situated upstream from the tube  910  connection location. It is possible for closing off of the ink flow passage to be done at any site upstream from the tube  910  connection location. 
     In Embodiment 2, because the tube  910  is connected to the downstream side of the differential pressure valve housing chamber  40   a , the function of the differential pressure valve  40  is not utilized. Accordingly, in Embodiment 2, in order that ink may be supplied at appropriate pressure to the print head from the cartridge it is preferable to keep the pressure of the ink delivered from the large-capacity ink tank  900  within an appropriate pressure range. It is acceptable for example to furnish the large-capacity ink tank  900  with a pressure maintenance or regulating mechanism. As one exemplary pressure maintenance mechanism, it is possible to employ a mechanism whereby the ink tank  900  is moved up or down to maintain the liquid level therein within an fixed height range from the nozzle faces of the print head, irrespective of the ink level inside the large-capacity ink tank  900 . In this case, the head differential from the nozzle face of the print head to the liquid level of the ink tank will preferably be within a range of about +100 mm and −500 mm. If this head differential is too great, the meniscus cannot be maintained at the nozzle face of the print head, and it is possible that ink will leak out inadvertently. On the other hand, if the head differential is too small, it is possible that a sufficient amount of ink cannot be delivered to the print head from the ink tank. In the case of an off-cartridge type ink-jet printer, however, since in most instances a differential pressure valve is provided to the print head, in such cases it will not be necessary to regulate the head differential between the large-capacity ink tank  900  and the print head. 
     In this way, in Embodiment 2, because the ink supply tube  910  has been connected downstream from the sensor section  30  in a manner comparable to Embodiment 1, ink supplied from the tube  910  will be delivered to the print head of the printer, making it possible to achieve stable ink delivery. Moreover, in Embodiment 2, in a manner analogous to the modified examples of Embodiment 1, it is possible for the tube  910  to be introduced from either the left or right wall face of the cartridge. 
     Although the tube  910  is connected to the vertical flow passage  460  in Embodiment 2, it is possible to obtain similar advantages by connecting the tube  910  to the other vertical flow passage  450  situated thereabove (see  FIG. 19A ). As long as the tube  910  is connected to either of the vertical flow passages  450 ,  460 , even if air bubbles flow into the cartridge via the tube  910  the bubbles will rise through the vertical flow passages  450 ,  460  and become trapped in the differential pressure valve chamber. A consequent advantage is that the bubbles will be prevented from proceeding into the print head. 
       FIGS. 22A and 22B  show a method of connecting an ink supply tube  910  to an ink cartridge in Embodiment 3. The ink supply tube  910  is passed through the top face  1   a  of the cartridge, the wall  370   w  in the upper part of the first ink holding chamber  370 , and the wall  430   w  of the buffer chamber  430 , so as to connect with the communication hole  432  between the buffer chamber  430  and the differential pressure valve housing chamber  40   a.  Consequently, ink supplied from the large-capacity ink tank  900  will be introduced directly into the differential pressure valve housing chamber  40   a.  In Embodiment 3, in the same manner as in Embodiment 1, the communication hole  311  between the second ink holding chamber  390  and the labyrinthine flow passage  400  is sealed. Sealing of the zones between the tube  910  and the wall faces  1   a ,  370   w ,  390   w  is optional. 
       FIG. 23  is a drawing depicting the A-A cross section of  FIG. 22A . The tube  910  is affixed with adhesive or the like in the communication hole  432  of the buffer chamber  430 . In  FIG. 23 , for convenience in illustration, the communication hole  432  is depicted as being at a location somewhat further towards the upper side than in  FIG. 22A . The tube  910  is depicted in its condition prior to being installed in the cartridge. 
       FIG. 24  is a conceptual depiction of the ink delivery system pathway in Embodiment 3. The large-capacity ink tank  900  has been connected to the differential pressure valve housing chamber  40   a  via the tube  910  so that ink may be delivered directly to the differential pressure valve housing chamber  40   a.  Consequently, as ink is consumed by the printer, the differential pressure valve  40  will open, and ink supplied from the large-capacity ink tank  900  will flow through the differential pressure valve  40  and the vertical flow passages  450 ,  460 , and be delivered to the print head of the printer via the liquid delivery port  50 . 
     In Embodiment 3, as in Embodiment 1, it is preferable to prevent air from flowing into the sensor section  30  from the air vent hole  100 . This is the reason for closing off the communication hole  311  which is situated upstream from the tube  910  connection location. It is possible for closing off of the ink flow passage to be done at any site upstream from the tube  910  connection location. 
     In this way, in Embodiment 3 as well, because the ink supply tube  910  has been connected downstream from the sensor section  30  in a manner comparable to Embodiment 1, ink supplied from the tube  910  will be delivered to the print head of the printer without passing through the sensor section  30  which represents an ink flow passage with high flow passage resistance, making it possible to achieve stable ink delivery. Also, as in Embodiment 1, in Embodiment 3 the function of the differential pressure valve  40  is utilized when delivering ink from the large-capacity ink tank  900  to the print head side. Furthermore, in Embodiment 3, since the distal end of the tube  910  need simply be fastened into the communication hole  432  that has been provided beforehand to the cartridge, there is the advantage of a simple tube connection operation. Also, the tube  910  may be connected to another communication hole in the cartridge, instead of the communication hole  432 . In this case as well, it will be preferable to connect the tube  910  to a communication hole that is situated on the downstream side of the sensor section  30 . Moreover, in Embodiment 3, in a manner analogous to the modified examples of Embodiment 1, it is possible for the tube  910  to be introduced from either the left or right wall face of the cartridge. 
     D. MODIFIED EXAMPLES  
     The present invention is not limited to the embodiments shown hereinabove, and may be reduced to practice in various other modes without departing from the spirit thereof, as in the possible modifications described below. 
     D1. Modified Example 1  
     While the preceding embodiments describe various flow passages, holding chambers, and communication holes provided to the ink cartridges, some of these arrangements may be dispensed with. 
     D2. Modified Example 2  
     While in the preceding embodiments, a large-capacity ink tank  900  is employed as the ink supply device, an ink supply device of some other configuration may be used. For example, it is possible to employ an ink supply device having a pump provided between the large-capacity ink tank  900  and the ink cartridge  1 . 
     D3. Modified Example 3  
     While the preceding embodiments have described an ink delivery system adapted for an ink-jet printer, the present invention is adaptable generally to liquid delivery systems that deliver a liquid to a liquid jetting device or a liquid consuming device; with appropriate modifications, it is possible for the invention to be employed in liquid consuming devices of various kinds equipped with a liquid jetting head adapted to eject small amounts of a liquid in drop form. Herein, a drop refers to the state of the liquid ejected from the liquid jetting device, and includes those with tails of granular, teardrop, or filiform shape. Herein, a liquid refers to any material that can be jetted from a liquid jetting device. For example, substances of any state when in the liquid phase would be acceptable including those of a high- or low-viscosity liquid state, of a fluid state such as a sol, gel water, or other inorganic solvent, organic solvent, solution, liquid resin, liquid metal (molten metal), or substances having the liquid state as one of their states; as well as materials containing particles of functional materials consisting of solids such as pigments or metal particles dissolved, dispersed, or mixed into a medium. Typical examples of liquids are the inks described in the preceding embodiments, and liquid crystals. Here, the term “ink” is used to include typical water based inks and oil based inks, as well as shellac, hot melt inks, and various other kinds of liquid compositions. Specific examples of liquid consuming devices are liquid jetting devices adapted to jet liquids containing materials such as electrode materials or coloring matter in dispersed or dissolved form, and employed in manufacturing liquid crystal displays, EL (electroluminescence) displays, plane emission displays, or color filters; liquid jetting devices adapted to jet liquids containing bioorganic substances used in biochip manufacture; liquid jetting devices adapted to jet liquids as specimens for use as precision pipettes; textile printing devices; or microdispensers. The system may further be employed as a delivery system in liquid jetting devices used for pinpoint application of lubricants to precision instruments such as clocks or cameras; in liquid jetting devices adapted to jet an ultraviolet curing resin or other transparent resin solution onto a substrate for the purpose of forming a micro semi-spherical lens (optical lens) for use in optical communication elements etc.; or in liquid jetting devices adapted to jet an acid or alkali etchant solution for etching circuit boards etc. The present invention is adaptable as a delivery system to any of the above types of liquid jetting devices. The liquid delivery systems that deliver liquid other than ink will employ a liquid flow passage member made of material suitable for the particular liquid, in place of the ink supply tube.