Patent Publication Number: US-2012023871-A1

Title: Liquid container and method of manufacturing the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a Divisional application of U.S. Ser. No. 12/252,390 filed Oct. 16, 2008, which claims priority on Japanese Patent Applications No. 2007-269355 filed on Oct. 16, 2007, No. 2008-075549 filed Mar. 24, 2008, and No. 2008-0750006 filed Mar. 24, 2008, the disclosures of which are hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a liquid container suitable for detecting an amount of remaining liquid (ink) in a liquid consuming apparatus such as an inkjet printing apparatus and a method of manufacturing the liquid container. 
     2. Related Art 
     As a representative example of a liquid consuming apparatus, there is an inkjet printing apparatus having an inkjet print head for printing an image. Other liquid ejecting apparatuses may include an apparatus having a coloring material ejecting head used for manufacturing a color filter and the like of a liquid crystal display, an apparatus having an electrode material (conductive paste) ejecting head used for forming electrodes of an organic EL display, a field emission display (FED), and the like, an apparatus having a biological organic material ejecting head used for manufacturing a bio chip, and an apparatus having a sample ejecting head as a precise pipette. 
     In the inkjet printing apparatus as the representative example of the liquid consuming apparatus, an inkjet print head having a pressure generator pressurizing a pressure generating chamber and nozzle orifices ejecting the pressurized ink as ink droplets is mounted on a carriage. By endlessly supplying the ink in an ink container to the print head through a flow channel, a printing operation can be continuously performed. The ink container is constructed as a detachable cartridge that can be replaced by a user when the ink is completely consumed. 
     There is a method of managing ink consumption by integrating the number of ink droplets emitted from the print head or the amount of ink sucked in maintenance by software or a method of managing when the ink is actually consumed by a predetermined amount by attaching a liquid level detecting electrode to the ink cartridge, as a method of managing the ink consumption of an ink cartridge. 
     However, the method of managing the ink consumption by integrating the number of ejected ink droplets or the amount of ink by software causes the following problem. The head may eject ink droplets with non-uniformity in weight. The non-uniformity in weight of the ink droplets does not affect the image quality but the ink with a margin is filled in the ink cartridge in consideration of accumulation of errors in ink consumption due to the non-uniformity. Accordingly, there is a problem that the ink corresponding to the margin remains in some apparatuses. 
     On the other hand, in the method of managing when the ink is consumed by the use of an electrode, since the actual amount of remaining ink can be detected, it is possible to manage the amount of remaining ink with high reliability. However, since the detection of the ink level depends on the conductivity of the ink, the kinds of ink detectable are limited, thereby complicating the sealing structure of the electrode. Since precious metals with excellent conductivity and anti-corrosion are usually used as the material of the electrode, the cost for manufacturing the ink cartridge is enhanced. Since two electrodes should be necessarily formed, the number of manufacturing processes increases, thereby increasing the manufacturing cost. 
     Therefore, to solve the above-mentioned problems, a piezoelectric device (herein, referred to as a sensor unit) is disclosed in JP-A-2001-146030. The sensor unit monitors the amount of ink remaining in the ink cartridge by the use of the resonance frequency of a residual vibration signal resulting from the residual vibration (free vibration) of a vibrating plate after forcible vibration when the ink remains and does not remain in a sensor cavity opposed to the vibrating plate having a piezoelectric element formed thereon. 
     In FIG. 8 of JP-A-2006-248201, plural vertical-direction changing portions changing the flow of ink in vertical directions are shown. The space above the vertical-direction changing portions serves as a bubble trapping space. 
     In FIGS. 9 and 14 of JP-A-2006-315302, a structure supporting a sensor base at three positions of a partition wall and both main case walls thereof is shown. In JP-A-2001-328277, a barrier wall is disposed in the liquid opposed to the sensor, whereby bubbles hardly enter the sensor cavity even when the bubbles are formed in the liquid level in the tank. 
     Techniques of securing a bypass channel of a liquid by not welding a part of a film covering an opening of a liquid passage and then closing the bypass channel of the liquid by welding the part of the film are disclosed in JP-A-2005-022257 and JP-A-2004-306466. 
     The technique disclosed in JP-A-2006-248201 employs a specific gravity separation method of trapping bubbles having small specific gravity in the upside by the use of a labyrinth channel on the basis of a difference in specific gravity between the liquid and the bubbles. 
     Here, as shown in FIG. 8 of JP-A-2006-248201, the ink is introduced from the lower position of the bubble trapping space and the ink is discharged from the lower position of the bubble trapping space. In this case, as described later, when the ink consumption rate is great due to a continuous printing operation and thus the ink flow rate is great, the bubbles in the bubble trapping space are sucked into the ink and discharged along with the ink in the vicinity of the ink end. Then, bubbles are formed in the buffer chamber in the just upstream side of the sensor cavity and the bubbles are detected by the sensor, thereby falsely detecting the ink end. 
     In the technique disclosed in JP-A-2006-315302, the vibration of the piezoelectric element is absorbed by the main case coming in contact with the sensor base at three positions, thereby making it difficult to satisfactorily guarantee the vibration being detectable by the piezoelectric element. Since the sensor base is positioned in an opening formed in the main case, bubbles may stay in minute gaps around the sensor base at the time of injecting the ink, thereby causing false detection of the ink end. This problem is not prevented even by the use of the barrier wall shown in JP-A-2001-328277. This is because the barrier wall hinders the flow of ink at the time of initially injecting the ink to easily generate bubbles around the sensor base. 
     SUMMARY 
     An advantage of some aspects of the invention is that it provides a liquid container that can prevent formation of bubbles in the immediate upstream of a sensor cavity even when the amount of remaining ink decreases, thereby enhancing the liquid detection precision. 
     Another advantage of some aspects of the invention is that it provides a liquid container that can reduce the false detection by employing a structure for enhancing the amplitude at the time of detecting the liquid and a structure for suppressing bubbles from staying around the sensor base at the time of introducing the liquid. 
     Another advantage of some aspects of the invention is that it provides a method of manufacturing a liquid container that can deliver bubbles to satisfactorily fill the liquid container with the liquid even when the bubbles are easily gathered due to its structure at the time of filling the liquid container with the liquid. 
     According to an aspect of the invention, there is provided a liquid container including: a case in which a flow channel of a liquid is exposed from an opening; a sensor base, disposed in the opening of the case to face the flow channel; a sensor chip, including: a piezoelectric element, mounted on a surface opposite to a surface of the sensor base which faces the flow channel; and a sensor cavity, disposed opposite to the piezoelectric element and adapted to receive the liquid as a detection target; a film, adapted to hold the sensor base in the opening and sealing the opening; a partition wall, partitioning the flow channel in the case into an upstream buffer chamber and a downstream buffer chamber; and a bubble trapping section, disposed upstream of the upstream buffer chamber. The bubble trapping section includes: a bubble trapping chamber, adapted to trap bubbles upside by allowing the liquid level to be lowered with reduction in an amount of remaining liquid at a time of consuming the liquid; an inlet, communicating at a vertical upper position of the bubble trapping chamber to introduce the liquid at the time of consuming the liquid; and an outlet, communicating at a vertical lower position of the bubble trapping chamber to discharge the liquid at the time of consuming the liquid. 
     According to an aspect of the invention, there is also provided a method of manufacturing a liquid container having a tank chamber, first and second communication holes communicating with the tank chamber, and a flow channel communicating with the first communication hole, the method including: welding a film to one surface of the liquid container in which openings communicating with the tank chamber and the flow channel, respectively, are formed; filing the tank chamber with a liquid from the second communication hole disposed in a vertical upper portion of the tank chamber; and delivering bubbles, which are gathered in the vertical upper portion of the tank chamber at a time of filling the tank chamber with the liquid, from the tank chamber to the flow channel through a bypass channel extending from an opening of the tank chamber to an opening of the flow channel through a non-welded portion of the film. 
     The present disclosure relates to the subject matter contained in Japanese patent application Nos. 2007-269355 filed on Oct. 16, 2007, 2008-75006 filed on Mar. 24, 2008 and 2008-75549 filed on Mar. 24, 2008, which are expressly incorporated herein by reference in its entirety. 
    
    
     
       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 a schematic perspective view of an inkjet printer as a liquid consuming apparatus. 
         FIG. 2  is an exploded perspective view of an ink cartridge. 
         FIG. 3  is an exploded perspective view of an ink detector where a part of  FIG. 2  is enlarged. 
         FIG. 4  is a sectional view schematically illustrating a flow channel according to an embodiment of the invention including a bubble trapping chamber on the upstream side in the ink detector. 
         FIG. 5  is a sectional view illustrating a bubble trapping chamber of a comparative example of  FIG. 4 . 
         FIG. 6  is a front view of the ink cartridge. 
         FIG. 7  is a sectional view taken along line A 1 -A 1  of  FIG. 6 . 
         FIG. 8  is a sectional view taken along line B 1 -B 1  of  FIG. 6 . 
         FIG. 9  is a right side view of the ink cartridge. 
         FIG. 10  is a perspective view of a sensor base as viewed from the rear side. 
         FIG. 11  is a perspective view illustrating a sensor base mounted with a sensor chip as viewed from the outside. 
         FIG. 12  is a sectional view of an assembled ink detector. 
         FIG. 13  is a diagram schematically illustrating a positional relation between first and second holes of the sensor base and a partition wall. 
         FIGS. 14A and 14B  are diagrams illustrating modified examples of the partition wall. 
         FIGS. 15A and 15B  are diagrams illustrating modified examples in which an assistant support portion is provided. 
         FIG. 16  is a diagram illustrating a modified example where the partition wall and the assistant support portion are provided in the sensor base. 
         FIG. 17  is a sectional view of the sensor chip. 
         FIG. 18  is a plan view schematically illustrating an attachment structure of the sensor base shown in  FIGS. 14B ,  15 B, and  16  as viewed from the upside of the drawings. 
         FIG. 19A  is a plan view illustrating the state equivalent to that of  FIG. 18 ,  FIG. 19B  is a sectional view taken along line A 2 -A 2  of  FIG. 19A , and  FIG. 19C  is a sectional view line B 2 -B 2  of  FIG. 19A . 
         FIG. 20  is a plan view illustrating a specific example of  FIGS. 19A to 19C . 
         FIG. 21  is a sectional view taken along line A 3 -A 3  of  FIG. 20 . 
         FIG. 22  is a sectional view taken along line B 3 -B 3  of  FIG. 20 . 
         FIG. 23  is a plan view illustrating a main case before the sensor base is mounted thereon. 
         FIG. 24A  is a plan view illustrating the state equivalent to those of  FIGS. 19A and 20  and  FIG. 24B  is a sectional view taken along line A 4 -A 4  of  FIG. 24A . 
         FIG. 25  is a view of the case body shown in  FIG. 2  as viewed from the film side. 
         FIG. 26  is an enlarged plan view of part C in  FIG. 25 . 
         FIG. 27  is an enlarged perspective view of part C in  FIG. 25 . 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Hereinafter, exemplary embodiments of the invention will be described in detail. The following embodiments do not excessively limit the scope of the invention described in the appended claims and all elements described in the embodiments are not essential to the solving means of the invention. 
     Ink Cartridge 
     An ink cartridge (liquid container) to which a liquid detecting device according to an embodiment of the invention is attached will be described now with reference to the accompanying drawings. 
       FIG. 1  is a diagram schematically illustrating a configuration of an inkjet printing apparatus (liquid consuming apparatus) employing the ink cartridge according to this embodiment. A carriage  1  is guided by a guide member  4  via a timing belt  3  driven by a carriage motor  2  and reciprocates in the axial direction of a platen  5 . 
     An inkjet print head  12  is mounted on a side of the carriage  1  facing a printing sheet  6 . An ink cartridge  100  supplying ink (water ink or oil ink) to the print head  12  is demountably mounted on a holder (not shown) disposed in the upper portion of the carriage  1 . 
     A cap member  13  is disposed at a home position (in the right side in  FIG. 1 ) which is a non-printing area of the printing apparatus. The cap member  13  is pressed on a nozzle formation surface of the print head  12  to form a closed space with the nozzle formation surface, when the print head  12  mounted on the carriage  1  moves to the home position. A pump unit  10  giving a negative pressure to the closed space formed by the cap member  13  to perform a cleaning process is disposed below the cap member  13 . 
     In the vicinity of a printing area in the cap member  13 , a wiping unit  11  having an elastic plate of rubber is disposed to reciprocate in the horizontal direction about the moving trace of the print head  12 . The wiping unit  11  wipes out the nozzle formation surface of the print head  12  as needed when the carriage  1  reciprocates with respect to the cap member  13 . 
       FIG. 2  is a perspective view schematically illustrating a configuration of an ink cartridge  100 . In  FIG. 1 , the ink cartridge  100  is disposed to correspond to the vertical direction in the state where the ink cartridge is mounted on the carriage  1 . Accordingly, the term “vertical” used in the following description means the vertical direction in the state where the ink cartridge  100  is mounted on the carriage  1 . 
     The ink cartridge  100  includes a film  104  covering the rear surface of the main case  102 , a cover member  106  covering the film  104  and the bottom surface of the main case  102 , and a film  108  covering the surface and the top surface of the main case  102 . 
     The main case  102  is partitioned by ribs or walls complexly. The main case  102  includes an ink channel section having an ink containing area and an ink delivery channel, an ink-side passage allowing the ink containing area to communicate with the atmospheric air, and an atmospheric communication portion having an atmospheric air valve receiving chamber and an atmospheric air-side passage, detailed description of which are omitted (for example, see JP-A-2007-15408). 
     The ink delivery channel of the ink channel section finally communicates with an ink supply section  110  and the ink in the ink cartridge  100  is sucked up from the ink supply section  110  for supply by the negative pressure. 
     An ink supply needle (not shown) of the holder disposed in the carriage  1  is inserted into the ink supply section  110 . The ink supply section  110  includes a supply valve  112  that is pressed by the ink supply needle and slides to open its valve, a sealing member  114  formed of an elastic material such as elastomer, which is fitted to the surrounding of the ink supply needle, and an urging member  116  formed of a coil spring to urge the sealing member  114  to the supply valve  112 . Theses elements are assembled by fitting the urging member  116 , inserting the sealing member  114  to the ink supply section  110 , and finally pushing the supply valve  112 . 
     A lever  120  engaging with the holder disposed in the carriage  1  is disposed on one side surface of the main case  102 . An opening  130  opened at a position corresponding to the upstream of the ink supply section  110  and the end of the ink delivery channel is formed at a position on one side surface of the main case  102 , for example, at a position below the lever  120 . A welding rib  132  is formed in the circumferential edge of the opening  130 . A partition rib  136  partitions the ink delivery channel  134  facing the opening  130  into an upstream buffer chamber  134   a  and a downstream buffer chamber  134   b  (the reference numerals are omitted in  FIG. 2 ; see  FIGS. 8 and 9 ) is formed. 
     Ink Detector 
     An ink detector  200  employing the liquid detector according to this embodiment, which is formed by the main case  102 , the ink delivery channel  134 , and the partition rib  136 , will be described now with reference to  FIGS. 2 and 3 .  FIG. 3  is an enlarged view of the ink detector  200  in the ink cartridge  100  shown in  FIG. 2 . 
     In  FIGS. 2 and 3 , the ink detector  200  includes a resin main case  102  in which the ink delivery channel  134  is formed, a metal sensor base  210  disposed in the opening  130  of the main case  102  to face the ink delivery channel  134 , a sensor chip  220  mounted on a surface of the sensor base  210  opposite to the surface facing the ink delivery channel  134 , a film  202  holding the sensor base  210  in the opening  130  and sealing the opening  130 , and a partition wall  136  partitioning the ink delivery channel  134  in the main case  102  into upstream and downstream. The film  202  is bonded to the top surface of the sensor base  210  and is welded to the welding rib  132  around the opening  130 . 
     In  FIGS. 2 and 3 , the ink detector  200  further includes a pressing cover  230  disposed above the sensor base  210 , the sensor chi p 220 , and the film  202 , a relay terminal  240  having terminals  242  electrically connected to the sensor chip  220  through a hole  202   a  formed in the film  202 , and a circuit board  250  received in the pressing cover  230  and electrically connected to the terminals  244  of the relay terminal  240 . In the liquid container  100  according to this embodiment, the pressing cover  230 , the relay terminal  240 , and the circuit board  250  are not essential elements. 
     Upstream Channel Structure of Ink Detector 
     Before describing in detail the ink detector, the channel structure upstream of the ink delivery channel  134  in the ink detector will be described with reference to  FIG. 4 . 
       FIG. 4  is a sectional view illustrating the most downstream portion including the ink detector  200  in the ink container according to this embodiment. In  FIG. 4 , a tank chamber (liquid containing chamber)  260  which is an ink containing area and a detour channel  270  having a labyrinth shape bent vertically and horizontally as a delivery channel communicating with the tank chamber are shown schematically. For example, a bubble trapping section  280  is disposed at the most downstream end of the detour channel  270 . The bubble trapping section  280  communicates with the ink delivery channel  134  of the ink detector  200  through, for example, a communication channel  290 . 
     The bubble trapping section  280  includes a bubble trapping chamber (tank chamber)  282  trapping the bubbles in the upper portion thereof with the lowering of the liquid level LH 1  due to the decrease in the amount of remaining ink at the time of consuming the ink, an inlet  284  introducing the ink at a vertical upper position of the bubble trapping chamber  282  at the time of consuming the ink, and an outlet  286  discharging the ink at a vertical lower position of the bubble trapping chamber  282  at the time of consuming the ink. 
     In this embodiment, the bubble trapping chamber  282  employs the specific gravity separation method of separating the ink and the bubbles by the use of a difference in specific gravity between the ink and the bubbles. The specific gravity separation method is known in a system for continuously supplying a liquid. This embodiment employs a structure for not mixing the bubbles into the ink, particularly, even when the amount of remaining ink decreases. 
     The bubble trapping chamber  282  traps the bubbles in the upper portion thereof with the lowering of the liquid level LH 1  due to the decrease in the amount of remaining liquid. The bubble trapping employs the specific gravity separation method without any change and is not different from that of the bubble trapping chamber used to endlessly supply the liquid. 
     In the course of trapping the bubbles when the amount of remaining ink decreases, the inlet  284  is located in the vertical upper portion of the bubble trapping chamber  282 . Then, the bubbles initially generated from the inlet  284 , but when the lower end of the bubble group does not reach the outlet  284 , no meniscus is formed in the inlet  284 , thereby stopping the generation of the bubbles. At the same time, the bubbles gathered in the upper portion are broken and merged to form a gas space, the liquid level of which is LH 1 . Then, in the bubble trapping chamber  282 , the mixture of the bubbles into the liquid is prevented. When the outlet  286  of the bubble trapping chamber  282  is located at the vertical lower position, only the liquid not containing the bubbles is discharged and thus the bubbles are not mixed in the communication channel  290  and the delivery channel  134  of the ink detector  200  downstream therefrom. Accordingly, the false detection is prevented at the time of detecting the ink end by detecting the bubbles. 
       FIG. 5  shows a comparative example of a related art. In the comparative example, the bubble trapping chamber  500  used to endlessly supply the liquid is made to communicate with the delivery channel  134  of the ink detector  200  through the communication channel  510 . That is, the inlet  502  and the outlet  504  of the bubble trapping chamber  500  are both located at the vertical lower position in the bubble trapping chamber  500 . In the bubble trapping chamber  500 , the bubbles having small specific gravity can be trapped in the vertical upper space. 
     However, in the comparative example, particularly, when the amount of ink consumption per unit time is great, the ink in the bubble trapping chamber  500  is replaced with the bubbles and thus a lot of bubbles may remain in the upstream portion therefrom when the bubbles reach the ink detector  200 . When time elapses in this state, the bubbles are finally broken and disappear, but the ink forming the bubbles may serve as the remaining ink and may enter the ink detector  200  at the time of consuming the ink, where the remaining ink may be detected later. In addition, the bubbles  506  in the bubble trapping chamber  500  are involved in the flow of ink and the bubbles are delivered to the delivery channel  134  of the ink detector  200  through the communication channel  510  downstream therefrom. Then, as described later, the bubbles enter the sensor cavity, thereby causing the false detection of the ink end. 
     Accordingly, in this embodiment shown in  FIG. 4 , the ink is introduced from the inlet  284  disposed at the upper position of the bubble trapping chamber  282  and the remaining of the bubbles in the ink can be satisfactorily prevented in the bubble trapping chamber  282  during the lowering of the liquid level LH 1  due tow the decrease in the amount of remaining ink. 
     In this embodiment, the bubble trapping chamber  282  may be connected directly to the delivery channel  134 , but the communication channel  290  may be disposed downstream of the bubble trapping chamber  282 . The communication channel  290  includes a supply hole  292  communicating with the outlet  286  of the bubble trapping chamber  282  at the time of consuming the ink and guides the ink introduced from the vertical lower position to the vertical upper portion. Then, the communication channel  290  introducing the ink from the outlet  294  located at the vertical upper position of the delivery channel  134  (upstream buffer chamber  134   a ) is further provided. 
     Accordingly, in the vicinity of the ink end after the ink in the bubble trapping chamber  282  is consumed, as shown in  FIG. 4 , the liquid level HL 2  in the delivery channel  134  (upstream buffer chamber  134   a ) is lowered and a meniscus is formed at that time. Therefore, in the delivery channel  134  (upstream buffer chamber  134   a ), the bubbles are removed from the liquid in the course of repeating the destruction and reconstruction of the meniscus. Accordingly, the false detection can be further prevented. 
     In this embodiment, a liquid containing chamber (tank chamber)  260  disposed upstream of the bubble trapping chamber  282  to contain the ink is opened to the atmospheric air as described above. Then, the space above the meniscus formed in the bubble trapping chamber  282  can be filled with the atmospheric air instead of the consumed ink. 
     In this embodiment, a detour channel  270  bent in a labyrinth shape is disposed between the bubble trapping chamber  282  and the liquid containing chamber (tank chamber)  260 . The detour channel  270  can also trap the bubbles. 
     In this embodiment, the ink cartridge may be disposed at the time of filling the ink container so that the bubble trapping chamber  282  has a posture vertically reverse to that at the time of consuming the ink. That is, at the time of filling the ink container, the bubble trapping chamber is vertically reverse and the ink is introduced from the outlet  286  located at the vertical upper position. Therefore, the bypass channel  288  opened at the time of filling the ink container to allow the bubble trapping chamber  282  to communicate with the detour channel  270  can be disposed vertically above the bubble trapping chamber  282  at the time of filling the ink container. The bypass channel  288  can deliver the bubbles gathered in the upper portion of the bubble trapping chamber  282  to the detour channel  270  at the time of filling the ink container. Accordingly, it is possible to prevent the bubbles from being mixed into the liquid in the bubble trapping chamber  282 . Since the gathering of the bubbles in the bubble trapping chamber  282  can be prevented, the bubble trapping chamber  282  can be filled with the ink. Accordingly, it is possible to prevent the false detection of the ink end due to the mixture of the bubbles even when a lot of ink remains in the bubble trapping chamber  282  of the ink detector  200 . The bypass channel  288  is closed at the time of consuming the ink. 
     Details of Ink Detector 
     Details of the ink detector  200  will be described now with reference to  FIGS. 6 to 13 .  FIG. 6  is a front view of the main case  102 . As shown in  FIG. 7  which is a sectional view taken along line A 1 -A 1  of  FIG. 6 , the ink delivery channel  134  is exposed from the opening  130  at the position close to the end before reaching the ink supply section  110  shown in  FIG. 1 . 
     As shown in  FIG. 8  which is a sectional view taken along line B 1 -B 1  of  FIG. 6  and  FIG. 9  which is a right side view of the ink cartridge  100 , the ink delivery channel  134  exposed from the opening  130  is partitioned into the upstream buffer chamber  134   a  and the downstream buffer chamber  134   b  by the partition wall  136 . The inlet  135   a  is disposed to face the upstream buffer chamber  134   a  as shown in  FIG. 8  and the outlet  135   b  is disposed to face the downstream buffer chamber  134   b  as shown in  FIG. 6 . 
       FIG. 10  is a perspective view of the sensor base  210  as viewed from the downside. As shown in  FIG. 10 , a first hole (supply path)  212  and a second hole (discharge path)  214  penetrating the sensor base  210  in the thickness direction are disposed. 
       FIG. 11  is a perspective view of the sensor base  210  mounted with the sensor chip  220  as viewed from the upside. 
       FIG. 12  is a sectional view schematically illustrating a state where the ink detector  200  shown in  FIGS. 2 and 3  is assembled.  FIG. 17  is a sectional view of the sensor chip. 
     In  FIGS. 12 and 17 , the sensor chip  220  has a sensor cavity  222  receiving the ink (liquid) as a detection target and the lower surface of the sensor cavity  222  is opened to receive the ink. The upper surface of the sensor cavity  222  is closed by a vibrating plate  224  as shown in  FIGS. 11 and 17 . A piezoelectric element  226  is disposed on the upper surface of the vibrating plate  224 . 
     Specifically, as shown in  FIG. 17 , the sensor chip  220  includes a vibration cavity forming base  300  that is constructed by stacking the vibrating plate  224  on a cavity plate  301  and that has a first surface  300   a  and a second surface  300   b  opposed to each other. The sensor chip  220  further includes the piezoelectric element  226  stacked on the second surface  300   b  of the vibration cavity forming base  300 . 
     In the vibration cavity forming base  300 , the cavity  222  having a cylindrical space shape for receiving the medium (ink) as the detection target is opened in the first surface  300   a  and the bottom surface  222   a  of the cavity  222  can be made to vibrate by the vibrating plate  224 . In other words, the portion actually vibrating in the vibrating plate  224  is defined in outline by the cavity  222 . Electrode terminals  228  and  228  are formed on both sides of the second surface  300   b  of the vibration cavity forming base  300 . 
     A lower electrode  310  is formed on the second surface  300   b  of the vibration cavity forming base  300  and the lower electrode  310  is connected to one electrode terminal  228 . 
     A piezoelectric layer  312  is stacked on the lower electrode  310  and an upper electrode  314  is stacked on the piezoelectric layer  312 . The upper electrode  314  is connected to an assistant electrode  320  insulated from the lower electrode  310 . The assistant electrode  320  is connected to the other electrode terminal  228 . 
     The piezoelectric element  226  performs the function of determining the ink end on the basis of the difference in electrical characteristics (such as frequency) due to the existence of the ink in the sensor cavity  222 . The piezoelectric layer may be formed of piezoelectric zirconate titanate (PZT), piezoelectric lead zirconate titanate (PLZT), or a lead-free piezoelectric film not containing lead. 
     The sensor chip  220  is fixed monolithically to the sensor base  210  by an adhesive layer  216  by placing the bottom of the chip body on the top center portion of the sensor base  210 , and the space between the sensor base  210  and the sensor chip  220  are sealed by the adhesive layer  216 . 
     Detection of Amount of Remaining Ink 
     As shown in  FIG. 12 , the ink introduced from the supply hole  135   a  of the ink delivery channel  134  stays in the upstream buffer chamber  134   a  which is one chamber partitioned by the partition wall  136 . 
     The upstream buffer chamber  134   a  communicates with the sensor cavity  222  of the sensor chip  220  through the first hole  212  of the sensor base  210 . Accordingly, the ink in the upstream buffer chamber  134   a  is guided to the sensor cavity  222  through the first hole  212  with the supply of the ink. Here, the vibration of the vibrating plate  224  made to vibrate by the piezoelectric element  226  is transmitted to the ink and the existence of the ink is detected on the basis of the frequency of the residual vibration waveform. In the endpoint where air enters the sensor cavity  222  in addition to the ink, the attenuation of the residual vibration waveform is great and the residual vibration waveform becomes a frequency higher than that of the case where the ink is filled full. By detecting the state, the ink end can be detected. 
     Specifically, when a voltage is applied to the piezoelectric element  226 , the vibrating plate  224  is deformed with the deformation of the piezoelectric element  226 . When the application of the voltage is stopped after the piezoelectric element  226  is forcibly deformed, the bending vibration remains in the vibrating plate  224  for a moment. The residual vibration is free vibration of the vibrating plate  224  and the medium in the sensor cavity  222 . Accordingly, by setting the voltage applied to the piezoelectric element  226  to a pulse waveform or a rectangular waveform, the resonance state of the vibrating plate  224  and the medium after the application of the voltage can be easily obtained. 
     The residual vibration is the vibration of the vibrating plate  224  and accompanies the deformation of the piezoelectric element  226 . Accordingly, the piezoelectric element  226  generates a back electromotive force with the residual vibration. 
     As shown in  FIG. 12 , the circuit board  250  includes an electrode  254  connected to a through-hole  252  penetrating the front and rear surfaces thereof. A signal from the relay terminal  240  contacting the sensor chip  220  is supplied through the through-hole  252  and the electrode  254  and is processed by an analysis circuit (not shown) mounted on the printer body, and the result is transmitted to a semiconductor memory (not shown) mounted on the circuit board  250 . That is, the back electromotive force of the piezoelectric element  226  is transmitted to the analysis circuit through the relay terminal  240  and the result is stored in the semiconductor memory. 
     Since the resonance frequency can be specified by the use of the back electromotive force detected as described above, the existence of the ink in the ink cartridge  100  can be detected on the basis of the resonance frequency. The semiconductor memory stores identification information such as the kind of the ink cartridge  100 , information on the color of the ink contained in the ink cartridge  100 , and information on the amount of remaining ink. 
     The ink staying in the sensor cavity  222  is guided to the downstream buffer chamber  134   b  through the second hole  214  of the sensor base  210  with the additional supply of the ink. The ink is supplied along the ink delivery channel  134  through the ink outlet  135   b , and is finally discharged from the ink cartridge  100  through the ink supply section  110  (see  FIG. 2 ). 
     Method and Structure for Supporting Sensor Base 
     When it is intended to fit the sensor base  210 , the sensor chip  220 , and the film  202  to the opening  130 , the following two processes are required. That is, a first process of disposing the metal sensor base  210  mounted with the sensor chip  220  in the opening  130  of the main case  102  having the flow channel  134  formed therein to face the flow channel  134  and a second process of welding the film  202  to the rib  132  around the opening  130  to allow the sensor base  210  to be supported by the main case  102  with the film  202  interposed therebetween are necessary. With the first process and the second process, the sensor cavity  222  formed in the sensor chip  220  communicates with the upstream buffer chamber  134   a  through the first hole  212  formed in the sensor base  210  and communicates with the downstream buffer chamber  134   b  through the second hole  214  formed in the sensor base  210 , thereby forming the detection path of the liquid as described above. 
     In this embodiment, in the first process before welding the film  202 , the sensor base  210  is supported by only the partition wall  136  (supporting function using the partition wall). Before the film  202  is welded to the welding rib  132  around the opening  130 , the sensor base  210  should be temporarily positioned at a predetermined position of the opening  130 . After the sensor base  210  is supported by the film  202  in the second process, the sensor base  210  can come in contact with only the partition wall  136  in the depth direction of the opening  130  (upstream and downstream partitioning function using the partition wall). Since the sensor base  210  is supported by the film  202 , the sensor base  210  does not always be in contact with the partition wall  136  but the upstream and downstream partitioning function of the partition wall  136  is always necessary. 
     Here, as shown in  FIG. 12 , in this embodiment, a channel wall  102   a  disposed opposite the sensor base  210  is provided to define the ink delivery channel  134 . The partition wall  136  is formed monolithically with the channel wall  102   a . The partition wall  136  is an essential structure for partitioning the ink delivery channel  134  into the upstream buffer chamber  134   a  and the downstream buffer chamber  134   b . This is because it is not guaranteed that the ink or the bubbles as the medium in the ink delivery channel  134  pass through the sensor cavity  222  when the partition wall  136  is not disposed. When the ink or the bubbles in the ink delivery channel  134  do not pass through the sensor cavity  222 , the sensor chip  220  false detects the end point of the ink. 
     In order to partition the ink delivery channel  134  into the upstream buffer chamber  134   a  and the downstream buffer chamber  134   b , the partition wall  136  should come in contact with the sensor base  210  or the gap between the sensor base  210  and the partition wall  136  is small so as not to allow the bubbles to pass through the gap. In other words, the flow resistance of the gap should be greater than the flow resistance of the first hole  212 , thereby not permitting the passage of the bubbles. This is the inherent function of the partition wall  136 . 
     On the other hand, the partition wall  136  is contacted and supported by the sensor base  210  at the time of fitting the sensor base  210  (first process), thereby preventing the sensor base  210  from falling into the opening  130 . That is, in the first process, the partition wall  136  has the function of temporarily supporting the sensor base  210 . 
     After the film  202  is welded to the welding rib  132  around the opening  130  and the sensor base  210  and the sensor chip  220  are attached to the opening  130 , the sensor base  210  comes in contact with only the partition wall  136 , except for the sensor chip  220  and the film  202 . That is, the sensor base  210  can come in contact with only the partition wall  136  in the depth direction of the opening  130 . 
     Accordingly, it is possible to detect the residual vibration waveform by the use of the piezoelectric element  226 . In this embodiment, the main case  102  of the ink detector  200  is a part of the main case of the ink cartridge  100  and has a great capacity. In general, the main case  102  is formed of a flexible resin material such as polypropylene and thus the absorption of vibration thereof increases with the increase in capacity. 
     Here, when the piezoelectric element  226  vibrates, the sensor base  210  mounted with the sensor chip  220  also vibrates in addition to the vibrating plate  224 . When the contact area between the sensor base  210  and the main case  102  is great, the vibration of the sensor base  102  is absorbed by the main case  102 . In this case, the amplitude of the residual vibration waveform is not enough to detect the residual vibration waveform by the use of the piezoelectric element  226 . 
     In this embodiment, since the sensor base  210  is supported by only the film  202  and the partition wall  136 , the vibration wave absorbed by the main case  102  is minimized and thus the amplitude enough to detect the residual vibration by the use of the piezoelectric element  226  is guaranteed. 
       FIG. 13  is a sectional view of the partition wall  136  as viewed from the downside. The partition wall  136  is located between the first and second holes  212  and  214  of the sensor base  210 . The thickness of the end of the partition wall  136  is the maximum when the partition wall  136  comes in contact with the first and second holes  212  and  214  and should not be set to clog the first and second holes  212  and  214 . The clogging enhances the flow resistance of the first and second holes designed with predetermined flow resistance. 
     Modified Example 
     Although this embodiment has been described in detail, it should be understood by those skilled in the art that the embodiment can be modified in various forms without departing from the idea and advantages of the invention. Therefore, the following modified examples should be included in the scope of the invention. For example, in the specification or drawings, a term described at least once along with another term having broader meaning or equivalent meaning can be replaced with the another term in any place of the specification or drawings. 
     As shown in  FIGS. 14A and 14B , the partition wall  136  may have a shape in which the thickness of the free end  136   b  is smaller than that of the base portion  136   a  close to the channel wall  102   a . That is, even when the base portion  136   a  is broader than the inter-edge distance of the first and second holes  212  and  214 , it does not cause any problem so long as the thickness of the free end  136   b  is equal to or less than the inter-edge distance as shown in  FIG. 12 . This is because it does not enhance the flow resistance of the first and second holes  212  and  214 . By broadening the base portion  136   a , the shaping property for the insertion molding can be improved. As the method of thinning the free end  136   b , the free end may not be tapered with a slope as shown in  FIG. 14B , but may be curved. 
     In order to enhance the stability of the attachment of the sensor base  210 , the configuration shown in  FIGS. 15A and 15B  may be employed. That is, an assistant support rib  138  may be provided in addition to the partition wall  136 . In  FIGS. 15A and 15B , two assistant support ribs  138  contactable with both ends in the longitudinal direction of the sensor base  210  are disposed. However, the height H 1  from the channel wall  102   a  to the end of two assistant support ribs  138  is smaller than the height H 2  to the end of the partition wall  136 . 
     In the embodiment shown in  FIG. 12 , since the sensor base  210  is supported by only the partition wall  136  at the time of attachment, the center of the sensor base  210  is supported like a seesaw, which provides bad stability. In the embodiment shown in  FIGS. 15A and 15B , even when the sensor base  210  is inclined, the lowered end thereof comes in contact with the assistant support rib  138  and is supported at two points including the partition wall  136 , which provides good stability. 
     However, regarding the assistant support rib  138 , since the sensor base  210  is substantially parallel to the channel wall  102   a  after the sensor base  210  is assembled as shown in  FIG. 15B , the sensor base  210  does not come in contact with the assistant supporting rib  138 . Accordingly, similarly to the embodiment shown in  FIG. 12 , the amplitude of the residual vibration waveform can be guaranteed greatly. 
     After the sensor base  210  is assembled, the assistant support rib  138  can prevent the sensor base  210  from being excessively inclined even in the abnormal state where falling impact force acts. Accordingly, it is possible to prevent the sensor base  210  supported by the film  202  from being excessively inclined to tear down the film  202 . 
     The position of the partition wall  136  is not limited to the channel wall  102   a . For example, as shown in  FIG. 16 , a partition wall  216  vertically extending downward from between the first and second holes  212  and  214  of the sensor base  210  may be provided. The partition wall  216  comes in contact with the channel wall  102   a  or is opposed to the channel wall with a slight gap having the flow resistance greater than the flow resistance of the first hole  212 . In  FIG. 16 , an assistant support rib  218  vertically extending downward from both ends in the longitudinal direction of the sensor base  210  is provided. The height H 1  from the bottom surface of the sensor base  210  to the end of two assistant support ribs  218  is smaller than the height H 2  to the end of the partition wall  216 . In this case, the same advantages as the embodiment shown in  FIGS. 15A and 15B  can be obtained. A partition wall may be disposed in one of the channel wall  102   a  and the sensor base  210  and an assistant support rib may be disposed in the other. In this way, when the partition wall  216  and/or the assistant support ribs  218  are disposed in the sensor base  210 , the sensor base  210  is subjected to, for example, a cutting process. 
     Structure for Preventing False Detection 
     A structure for preventing the false detection due to the bubbles will be described now with reference to  FIGS. 18 to 23 . 
       FIG. 18  is a plan view schematically illustrating an attachment structure of the sensor base  210  shown in  FIGS. 14B ,  15 B, and  16  as viewed from the upside of the drawings. However, the film  202  is omitted from  FIG. 18 . As shown in  FIG. 18 , in a state where an opening  102 A is formed in the main case  102  and the sensor base  210  is disposed in the opening  102 A, the sensor base  210  is supported by the film  202 . However, in  FIG. 18 , the film  202  is not shown. 
     Here, a slight gap D 1  is formed between the inner wall of the opening  102 A and four sides of the sensor base  210 . By setting a margin in design to reduce the gap D 1 , the sensor base  210  is positioned in the opening  102 A. 
     A problem of the structure shown in  FIG. 18  will be described. At the time of filling the main case  102  with the ink, the ink is filled in the main case  102  in a state where the main case is almost in vacuum. At this time, the gap D 1  communicates with the upstream buffer chamber  134   a  or the downstream buffer chamber  134   b  shown in  FIG. 12  but is narrow enough not to pass the ink. Accordingly, when the ink is fully filled in the upstream buffer chamber  134   a  or the downstream buffer chamber  134   b , bubbles remain in the gap D 1 . 
     Since the film  202  is formed of, for example, polypropylene (PP) and thus has the gas transmitting property, the bubbles grow in a great size by attracting the gas for a long time. The grown bubbles depart from the gap D 1  due to the vibration of the piezoelectric element  226  (see  FIG. 1 ) on the sensor base  210  and enter the upstream buffer chamber  134   a  or the downstream buffer chamber  134   b  communicating with the sensor cavity  222  shown in  FIG. 12 . When the bubbles reach the sensor cavity  222 , the ink end is falsely detected in spite of the remaining ink. 
     A structure for improving this problem is schematically shown in  FIGS. 19A to 19C .  FIG. 19A  is a plan view of the same state as shown in  FIG. 18 .  FIG. 19B  is a sectional view taken along line A 2 -A 2  of  FIG. 19A  and  FIG. 19C  is a sectional view taken along line B 2 -B 2  of  FIG. 19A . 
       FIG. 19A  shows a principle for solving the problem and it is thus that the sensor base  210  schematically shown is a rectangular shape having four sides. Four positioning portions  410 ,  411 ,  412 , and  413  protruding to four sides of the sensor base  210  are locally disposed at positions of the opening  402  opposed to four sides of the sensor base  210 . 
     At this time, as shown in  FIG. 19A , the gap D 1  is formed between the length in the lateral direction of the sensor base  210  and the distance between the positioning portions  410  and  412 . Similarly, the gap D 1  is formed between the length in the longitudinal direction of the sensor base  210  and the distance between the positioning portions  411  and  413 . By defining the gap D 1  as a size margin in design, the sensor base  210  can be positioned by the use of four positioning portions  410  to  413 . The size of the gap D 1  is equal to the size of the gap D 1  shown in  FIG. 18  and the gap D 1  is too narrow to pass the ink. 
     On the other hand, in the area other than four positioning portions  410 ,  411 ,  412 , and  413 , a gap D 2  sufficiently greater than the gap D 1  based on the design margin is formed between the wall portion of the opening  402  and four sides of the sensor base  210 . The gap D 2  forms a part of the flow channel  134  formed by the upstream buffer chamber  134   a  or the downstream buffer chamber  134   b  shown in  FIGS. 19B and 19C  and partitioned by the partition wall  136  shown in  FIG. 19A . 
     That is, at the time of injecting the ink, the ink is introduced into the sensor cavity  222  through the first hole  212  of the sensor base  210  as indicated by the solid line in  FIG. 19B , but the ink introduced from the inlet  135   a  to the upstream buffer chamber  134   a  is diffused by the wall (sensor base  210 ) located in the traveling direction and also flows in the gap D 2  around the sensor base  210  as indicated by the broken line in  FIG. 19B . Alternatively, the ink is discharged from the sensor cavity  222  to the outlet  135   b  through the second hole  214  of the sensor base  210  as indicated by the solid line in  FIG. 19C , but the ink discharged from the second hole  214  is diffused by the wall (wall of the downstream buffer chamber  134   b ) located in the traveling direction and also flows in the gap D 2  around the sensor base  210  as indicated by the broken line in  FIG. 19B . 
     In this way, the gap D 2  is filled with the ink and thus the bubbles do not remain. Accordingly, it is possible to prevent the false detection of the ink end. 
     When it is intended for the ink to easily flow in the gap D 2 , it is preferable that the inlet  135   a  of the upstream buffer chamber  134   a  is located at a position not opposed to the first hole  212  of the sensor base  210  and the outlet  135   b  of the downstream buffer chamber  134   b  is located at a position not opposed to the second hole  214  of the sensor base  210 . Accordingly, as described above, since the wall exists in the traveling direction of the ink introduced or discharged, the ink is diffused and easily flows in the gap D 2 . 
     Here, two positioning portions  410  and  412  of four positioning portions exist in an extension line of the partition wall  136  (see  FIG. 19A ). Otherwise, the flow channel connecting one side of the partition wall  136  to the other side is formed by the gap D 2  and thus the ink channel not passing through the sensor cavity  222  is formed. 
     Amore specific example of the example shown in  FIGS. 19A to 19C  is shown in  FIGS. 20 to 23 .  FIG. 20  is a plan view illustrating a specific example of  FIGS. 19A to 19C .  FIG. 21  is a sectional view taken along line A 3 -A 3  of  FIG. 20 .  FIG. 22  is a sectional view taken along line B 3 -B 3  of  FIG. 20 .  FIG. 23  is a plan view of the main case  400  before the sensor base  210  is fitted thereto. 
     As shown in  FIG. 20 , a ring-shaped welding rib  404  thermally welded to the film  202  (not shown) is formed around the opening  402  of the main case  400 . The sensor base  210  has four sides in total, in which two sides are opposed to each other in two axes perpendicular to each other. The sensor base  210  has four sides to be positioned and the shape for connecting the sides is not limited. 
     As shown in  FIGS. 20 to 23 , four positioning portions  410 ,  411 ,  412 , and  413  protruding to four sides of the sensor base  210  are disposed at positions opposed to four sides of the sensor base  210  in the opening  402 . The positioning portion  410  has a longitudinal shape along one side, that is, the longitudinal side, of the sensor base  210 . The other positioning portions  411  to  413  are locally disposed with respect to the other three sides of the sensor base  210 . 
     By setting the design margin on the gap D 1  (omitted in  FIGS. 20 and 21 ) between four sides in total of the sensor base  210 , in which two sides are opposed to each other in two axes perpendicular to each other, and four positioning members  410  to  413  opposed to four sides, the sensor base  210  is positioned in the opening  402 . By forming at least one positioning portion  410  of four positioning portions in a longitudinal shape along one side, particularly, the longitudinal side, of the sensor base  210 , the sensor base  210  can be effectively positioned in the rotation direction thereof. However, it is not preferable in view of the generation of bubbles that a lot of gaps D 1  are set, but it is preferable in view of the regulation of rotation that the longitudinal positioning portion is formed along only one side. 
     In the area other than four positioning portions  410 ,  411 ,  412 , and  413 , the gap D 2  sufficiently greater than the gap based on the design margin is formed between the wall portion of the opening  402  and four sides of the sensor base  210 . The gap D 2  forms a part of the flow channel  134  formed by the upstream buffer chamber  134   a  and the downstream buffer chamber  134   b  partitioned by the partition wall  136 . 
     As described above, the ink is filled in the main case  400  in a state where the main case is almost in vacuum. At this time, the gap D 2  communicating with the upstream buffer chamber  134   a  or the downstream buffer chamber  134   b  can form the flow channel of the ink. Accordingly, when the ink is fully filled in the upstream buffer chamber  134   a  or the downstream buffer chamber  134   b , the gap D 2  is filled with the ink and thus bubbles do not remain in the gap D 2 . Accordingly, it is possible to prevent the false detection of the ink end. 
     Two opposed positioning portions  410  and  412  of four positioning portions exist in the extension line of the partition wall  136  (see  FIG. 23 ) to prevent the flow channel not passing the sensor cavity  222  from being formed. 
     In the example shown in  FIGS. 20 to 23 , the inlet  135   a  of the upstream buffer chamber  134   a  is located at a position not opposed to the first hole  212  of the sensor base  210  and the outlet  135   b  of the downstream buffer chamber  134   b  is located at a position not opposed to the second hole  214  of the sensor base  210 . The positions of the inlet  135   a  and the outlet  135   b  may be set as shown in  FIGS. 24A and 24B .  FIG. 24A  is a plan view illustrating the state equivalent to that of  FIG. 19A  and  FIG. 24B  is a sectional view taken along line A 4 -A 4  of  FIG. 24A . 
     In the example shown in  FIGS. 24A and 24B , the inlet  135   a  disposed in the upstream buffer chamber  134   a  and the outlet  135   b  disposed in the downstream buffer chamber  134   b  are both disposed at positions opposed to the gap D 2  of the opening  402 . In this case, it is preferable that a partition wall  134   a   1  partitioning the inlet  135   a  and the upstream buffer chamber  134   a  and a partition wall  134   b   1  partitioning the outlet  135   b  and the downstream buffer chamber  134   b  are provided. 
     The ink introduced from the inlet  135   a  travels straightly and flows in the gap D 2 . Preferably, the ink is guided by the partitioning wall  134   a   1  to flow in the gap D 2 . Similarly, the ink discharged from the second hole  216  of the sensor base  210  is diffused by the downstream buffer chamber  134   b  to flow in the gap D 2 . Preferably, the ink is guided by the partition wall  134   b   1  to flow in the gap D 2 . 
     Details of Bypass Channel 
     The details of the bypass channel  288  for removing the bubbles described with reference to  FIG. 4  will be described with reference to  FIGS. 25 to 27 .  FIG. 25  is a view of the case body  102  shown in  FIG. 2  as viewed from the film  104 .  FIG. 26  is an enlarged plan view of part C in  FIG. 25 .  FIG. 27  is an enlarged perspective view of part C. 
     In  FIGS. 26 and 27 , the case body  102  is provided with a tank chamber  260  as a liquid containing chamber, a detour channel  270 , and a bubble trapping chamber  282 , which have openings opened on the attachment surface side of the film  104  ( FIG. 2 ), respectively. The film  104  is thermally welded to a sealing surface  600  close to the surface of the case body  102  to which the film  104  is attached. Accordingly, the openings of the tank chamber  260 , the detour channel  270 , and the bubble trapping chamber  282  are liquid-tightly sealed. 
     Here,  FIGS. 25 to 26  show a filling posture at the time of filling the ink cartridge  100  with the ink, instead of the posture shown in  FIG. 2  at the time of consuming (using) the ink. That is, the posture of the ink cartridge  100  is vertically reverse at the time of consuming the ink and at the time of filling the ink cartridge  100 . At the time of filling the ink cartridge, the ink is filled from the ink supply section  110  with the ink supply section  110  facing the upside. 
     At the time of filling the ink cartridge, the ink is introduced into the bubble trapping chamber  282  from the outlet  286  disposed in the vertical upper portion of the bubble trapping chamber  282 . At this time, the ink is discharged to the detour channel  270  from the inlet  284  disposed in the vertical lower portion of the bubble trapping chamber  282 . That is, at the time of filling the ink cartridge, the vertical position is reverse to that at the time of consuming (using) the ink, and the inlet  284  serves as the outlet and the outlet  286  serves as the inlet. That is, the functions are also reversed. Hereinafter, in order to avoid the confusion in title and function at the time of consuming (using) the ink and at the time of filling the ink cartridge, the inlet  284  and the outlet  286  are referred to as a first communication hole  284  and a second communication hole  286 , respectively. 
     In the posture shown in  FIG. 2  at the time of consuming (using) the ink, the positional relation of the first and second communication holes  284  and  286  relative to the bubble trapping chamber  282  is useful, in that the bubbles can be trapped. 
     However, at the time of filling the ink cartridge when the positional relation is reversed and the inlet and the outlet are also reversed, the positional relation of the first and second communication holes  284  and  286  relative to the bubble trapping chamber  282  is not desirable. The second communication hole  286  shown in  FIG. 27  is located in the vertical upper portion of the bubble trapping chamber  282  and serves as the inlet at the time of filling the ink cartridge. On the other hand, the first communication hole  284  shown in  FIG. 27  is located in the vertical lower portion of the bubble trapping chamber  282  and serves as the outlet at the time of filling the ink cartridge. When the ink is charged from the second communication hole  286  located in the vertical upper portion of the bubble trapping chamber  282  and the ink is discharged from the first communication hole  284  located in the vertical upper portion of the bubble trapping chamber  282 , a stagnation portion where the bubbles are gathered can be easily formed in the vertical upper portion of the bubble trapping chamber  282 . When there is no place to which the bubbles are delivered, the bubble trapping chamber  282  is not filled with the ink. In addition, the bubbles remaining in the bubble trapping chamber  282  move to the ink detector  200  at the time of consuming the ink and enters the sensor cavity  222 , thereby causing the false detection of the ink end. 
     Therefore, a bypass channel  288  for pulling out the bubbles is provided. The bypass channel  288  is similar to that of JP-A-2005-022257 and JP-A-2004-306466 in that a part of the film  104  is not welded, but is different from that of JP-A-2005-022257 and JP-A-2004-306466 in installation position and usage or object. 
     As shown in  FIG. 27 , the bypass channel  288  is guaranteed by one or more protrusion  610 , for example, three protrusions  610  in this embodiment, protruding from the sealing surface  600  by a height T. When the protrusions  610  are not welded to the film  104 , a gap formed by the protrusions  610  is guaranteed between the sealing surface  600  formed on one surface of the case body  102  and the film  104 . The gap serves as the bypass channel  288 . More specifically, the opening of the detour channel  270  is made to communicate with the opening of the bubble trapping chamber  282  through the non-welded portion (particularly, between two protrusions  610 ) of the film  104  from the opening of the bubble trapping chamber  282 , thereby forming the bypass channel  288 . 
     The bypass channel  288  may be formed by one or more grooves depressed from the sealing surface  600  by a predetermined depth. When the grooves are not welded to the film  104 , a gap is guaranteed between the bottom of the groove and the film  104 . 
     Method of Manufacturing Liquid Container 
     A method of manufacturing the ink cartridge  100  (liquid container) including the case body having the structure shown in  FIGS. 25 to 27  has the following processes. First, the film  104  shown in  FIG. 2  is welded to the sealing surface  600  formed on one surface of the case body  102  having the openings communicating with the bubble trapping chamber  282  and the detour channel, respectively. At this time, as described above, the protrusions  610  or the grooves are used as the non-welded portions to which the film  104  is not welded, so as to guarantee the bypass channel  288 . The welding work is preferably is performed with the ink cartridge  100  placed in the depressurized atmosphere. In this case, useless air does not enter the ink channel in the ink cartridge  100 . 
     Then, the posture at the time of consuming the ink (see  FIGS. 2 ,  3 , and  6 ) is a posture where the ink cartridge  100  is vertically reversed (see  FIGS. 25 to 27 ). In this posture, the ink is supplied from the ink supply hole  110 . At the time of filling the ink cartridge, the ink is introduced into the bubble trapping chamber from the second communication hole  286  disposed in the vertical upper portion of the bubble trapping chamber  282 . The introduction of the ink is smoothly carried out by depressurizing the ink channel, in addition to the ink supply pressure. The filling of the ink cartridge may be carried out while discharging the air from an opening (not shown) more downstream of the detour channel  270  for depressurization. The ink in the bubble trapping chamber  282  is supplied to the detour channel  270  or the tank chamber  260  downstream therefrom through the first communication hole  284  located in the vertical lower portion of the bubble trapping chamber  282 . 
     At the time of filling the ink cartridge, the bubbles gathered in the vertical upper portion of the bubble trapping chamber  282  is delivered from the bubble trapping chamber  282  to the detour channel  270  through the bypass channel  288  extending from the opening of the bubble trapping chamber  282  to the opening of the detour channel  270  through the non-welded portions of the film  104 . The bubbles are discharged to the outside from an end opening opened to the atmospheric air. When the air is discharged from the opening downstream of the detour channel  270  for depressurization, the bubbles are forcibly discharged from the ink cartridge  100 . 
     After finishing the ink filling process, the non-welded portions of the film  104  are welded to close the bypass channel  288 . The bypass channel  288  is necessary only at the time of filling the ink cartridge, but not necessary at the time of consuming the ink. 
     The method of manufacturing the liquid container is not limited to the ink cartridge  100  shown in  FIGS. 25 to 27 , and the application of the liquid container is not limited to the ink cartridge of the inkjet printing apparatus. The invention may be applied to a variety of liquid consuming apparatuses having a liquid ejecting head for ejecting minute ink droplets. 
     Specific examples of the liquid consuming apparatuses may include an apparatus having a coloring material ejecting head used for manufacturing a color filter of a liquid crystal display and the like, an apparatus having an electrode material (conductive paste) ejecting head used for forming electrodes of an organic EL display, a field emission display (FED), and the like, an apparatus having a biological organic material ejecting head used for manufacturing a bio chip, an apparatus having a sample ejecting head as a precise pipette, and a printing apparatus or a micro dispenser. 
     The liquid container according to the embodiment of the invention is not limited to the on-carriage type ink cartridge, but may be a sub tank not mounted on the carriage or an off-carriage type ink cartridge. 
     In the above-mentioned embodiments, the case body of the liquid detector is also used as the case body of the liquid container and the sealing rubber or spring described in JP-A-2006-248201 is excluded, but the invention is not limited to the configuration. The liquid detector can be configured as a unit independent of the case body of the liquid container. In this case, the sealing rubber or spring may not be excluded, but it can contribute to suppressing the absorption of vibration in the unit case in minimum and guaranteeing the amplitude of the detected waveform greatly, even when the unit case increases in size. 
     In the above-mentioned embodiment, the liquid ejecting apparatus may be embodied in a so-called full-line type (line head type) printer in which the whole shape of the print head  19  corresponds to the length in the width direction (lateral direction) of a printing sheet (not shown) in the direction intersecting the transport direction (longitudinal direction) of the printing sheet (not shown). 
     In the above-mentioned embodiment, the liquid ejecting apparatus is embodied in the inkjet printer  11 , but not limited to the inkjet printer. The invention may be embodied in a liquid ejecting apparatus spraying or ejecting a liquid (including a liquid material in which functional material particles are dispersed or mixed in a liquid and a fluid material such as gel) other than the ink. Examples thereof include a liquid material ejecting apparatus ejecting a liquid material including in a dispersed or dissolved type a material such as electrode material or coloring material (pixel material) used for manufacturing a liquid crystal display, an electroluminescence (EL) display, or a surface emission display, a liquid ejecting apparatus ejecting a biological organic material used for manufacturing a bio chip, and a liquid ejecting apparatus ejecting a liquid as a sample in a precise pipette. Examples thereof can also include a liquid ejecting apparatus ejecting lubricant to a precise machine such as a watch or camera with a pin point, a liquid ejecting apparatus ejecting transparent resin liquid such as UV-curable resin to a substrate to form minute semi-spherical lenses (optical lenses) used in optical communication devices, a liquid ejecting apparatus ejecting etchant such as acid or alkali to etch a substrate and the like, and a fluid material ejecting apparatus ejecting a fluid material such as gel (for example, physical gel). The invention can be applied to at least one kind of the above-mentioned liquid ejecting apparatuses. In this specification, the “liquid” does not include a liquid containing only gas, and examples of the liquid include a liquid material and a fluid material, in addition to inorganic solvent, organic solvent, solution, liquid-phase resin, and liquid-phase metal (metal solution). 
     The above-mentioned manufacturing method may be applied to a liquid container having a tank chamber containing a liquid, not the liquid container in which the bubble trapping chamber  282  is filled with the liquid. That is, the invention is not limited to trapping the bubbles at the time of consuming the liquid as described above. There may be a need for removing the bubbles staying at the time of filling the liquid container and filling the tank chamber with the liquid without trapping the bubbles. 
     In other words, in the method of manufacturing a liquid container according to the embodiment of the invention, the posture for use and the posture for filling may not be necessarily reverse. In some applications, there may be a need for a structure not requiring the consumption of liquid or for allowing the first and second communication holes  284  and  286  in the tank chamber to have the same positional relation as described above for the reason other than the bubble trapping. The detour channel  270  is not essential, but a flow channel connected to the first communication hole  284  may be used. 
     For example, there may be a liquid container as a kind of buffer in which a liquid always flows in one direction at the time of filling and consuming. In this case, since the bubbles should be removed from the tank chamber instead of the bubble trapping chamber  282 , it is not necessary to close the bypass channel  288  after filling the liquid container.