Abstract:
An ink supplying system has a first pipe having one end that connects to a main ink tank storing ink containing no air and another end that removably connects to a primary auxiliary ink tank that receives ink from the main ink tank. A second pipe has one end that removably connects to the primary auxiliary ink tank. An ink jet head is connected to another end of the second pipe for performing printing by ejecting ink on a printing medium. A secondary auxiliary ink tank has a capacity smaller than that of the primary auxiliary ink tank and is selectively exchangeable with the primary auxiliary ink tank for removing air in the ink supplying system prior to printing by the ink jet head. The secondary auxiliary ink tank has a connection pipe that removably connects to the another end of the first pipe and to the one end of the second pipe in fluid communication therewith. The connection pipe has the same sectional area as that of the first and second pipes.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to an ink supplying system for an ink jet printer, an ink supplying method for an ink jet printer, and an ink jet printer. 
     2. Background Art 
     In a conventional ink jet printer, an intermediate ink storing bag (auxiliary tank) is used in an ink passage that connects an ink cartridge (main tank) that stores ink and an ink jet head that ejects the ink and performs recording on a recording medium. This intermediate ink storing bag is provided in order to continue printing with the ink jet head even at the time of replacement of the ink cartridge. The intermediate ink storing bag is made of a flexible bag in order to store a predetermined volume of ink. At the top of the intermediate ink storing bag, for degassing at the time when the ink is filled or replaced, a tube that is arranged upward and has an on-off valve is provided (see, for example, Patent Document JP 2004-203056 A). 
     During ink filling in starting the ink jet printer, the ink is supplied from the ink cartridge to the ink jet head through the ink passage and via the intermediate ink storing bag. When the ink is supplied, because the intermediate ink storing bag is made of the flexible bag, the air tends to be accumulated in the inside thereof. Therefore, the air accumulated in the intermediate ink storing bag is exhausted by the on-off valve provided at the top. 
     However, in the conventional ink jet printer, the tube and the on-off valve as mechanisms for removing the air are attached even during normal use, and hence the ink jet printer is increase in size and complicated. The air removing by the tube provided in the upper part of the intermediate ink storing bag is extremely difficult because the on-off valve is adjusted while states of the air and the ink discharged to the tube are observed. 
     The present invention is made in view of the above-mentioned problems, and the object of the present invention is to provide an ink supplying system for an ink jet printer, an ink supplying method for an ink jet printer, and an ink jet printer with which ink supply work in starting to use the ink jet printer is easy and that can be reduced in size. 
     SUMMARY OF THE INVENTION 
     In order to solve the above-mentioned problems, the present invention proposes means described below. 
     An ink supplying system for an ink jet printer according to the present invention includes: a first pipe having one end which is connected to a main tank in which ink is stored with air therein being eliminated; a second pipe having one end which is connected to an auxiliary tank connected to another end of the first pipe with air therein being eliminated; and an ink jet head that is connected to another end of the second pipe, ejects the ink, and performs printing on a printing medium, in which the another end of the first pipe and the one end of the second pipe can be at least connected to or separated from the auxiliary tank or an auxiliary connecting means that is used in replacement of the auxiliary tank and has a capacity smaller than that of the auxiliary tank, and, a detachable unit that connects or separates, in connecting or separating the another end of the first pipe or the one end of the second pipe, the another end or the one end without allowing the air to flow into the auxiliary tank or the auxiliary connecting means is provided. 
     According to the present invention, it is possible to replace the auxiliary tank connected to the another end of the first pipe and the one end of the second pipe with the auxiliary connecting means and use the auxiliary connecting means. 
     Further the internal volume of the auxiliary connecting means is smaller than that of the auxiliary tank, and hence it is possible to easily fill the ink into the auxiliary connecting means. In a state in which the auxiliary connecting means is connected to the another end of the first pipe and the one end of the second pipe, if the ink stored in the main tank is led from the first pipe, it is possible to fill the ink while preventing the air from entering the first pipe, the auxiliary connecting means, the second pipe, and the ink jet head. 
     Further, the auxiliary connecting means is replaced with the auxiliary tank, from which the air is eliminated, by making use of the detachable unit, and the ink stored in the main tank is filled into the auxiliary tank, from which the air is eliminated. Consequently, the main tank, the first pipe, the auxiliary tank, the second pipe, and the ink jet head can be filled with the ink. 
     Therefore, the removing of bubbles contained in the ink, which was conventionally performed by the on-off valve provided to the tube provided in the auxiliary tank is unnecessary. Therefore, ink supply work in starting to use the ink supplying system of the ink jet printer can be facilitated. 
     Further, the tube and the on-off valve provided in the conventional auxiliary tank are unnecessary. Moreover, the auxiliary connecting means as a component used for removing the air in the ink supplying system is removed during the normal use. Therefore, the configuration of the entire ink supplying system of the ink jet printer can be reduced in size and simplified. 
     Further, it is preferable that the auxiliary connecting means have a connection pipe that directly connects a connecting section with the another end of the first pipe and a connecting section with the one end of the second pipe, and detachable mechanisms that can perform connection and separation without allowing the air to flow into the auxiliary tank or the auxiliary connecting means be provided in a connecting section of each of the another end of the first pipe and the one end of the second pipe and the auxiliary tank and a connecting section of each of the another end of the first pipe and the one end of the second pipe and the auxiliary connecting means. 
     According to the present invention, the connection pipe in the auxiliary connecting means is configured to directly connect the two connecting sections, and hence the air in the pipe tends to leak when the ink is filled. Therefore, in a state in which the auxiliary connecting means is connected to the another end of the first pipe and the one end of the second pipe, if the ink stored in the main tank is led from the first pipe, the ink can be filled into the first pipe, the connection pipe, the second pipe, and the ink jet head without letting the air into the same. 
     Further, the auxiliary connecting means is replaced with the auxiliary tank, from which the air is eliminated, by using the detachable mechanism without allowing the air to flow into the auxiliary tank. The ink stored in the main tank is filled into the auxiliary tank, from which the air is eliminated. Consequently, the main tank, the first pipe, the auxiliary tank, the second pipe, and the ink jet head can be filled with the ink without letting the air into the same. 
     Therefore, the removing of bubbles contained in the ink, which was conventionally performed by the on-off valve provided to the tube provided in the auxiliary tank is unnecessary. Therefore, ink supply work in starting to use the ink supplying system of the ink jet printer can be facilitated. 
     Further, the tube and the on-off valve provided in the conventional auxiliary tank are unnecessary. Moreover, the auxiliary connecting means as a component used for removing the air in the ink supplying system is removed during the normal use. Therefore, the configuration of the entire ink supplying system of the ink jet printer can be reduced in size and simplified. 
     Further, it is preferable that the auxiliary tank be filled with the ink with the air therein being eliminated. 
     According to the present invention, the auxiliary tank is filled with the ink with the air therein being eliminated. Therefore, in the ink supply work in starting to use the ink supplying system of the ink jet printer, a process for filling the ink stored in the main tank into the auxiliary tank is unnecessary. Therefore, the ink supply work can be performed in short time. 
     Further, it is preferable that an ink supplying system for an ink jet printer described above and a suction pump that sucks the ink from the ink jet head side be provided. 
     According to the present invention, the ink stored in the main tank can be automatically filled into the first pipe, the auxiliary connecting means, the second pipe, and the ink jet head with the suction pump. Therefore, the ink supply work can be more easily performed in starting to use the ink jet printer. 
     Further, the tube and the on-off valve provided in the conventional auxiliary tank are unnecessary. Moreover, the auxiliary connecting means as a component used for removing the air in the ink supplying system is removed during the normal use. Therefore, the configuration of the entire ink jet printer can be reduced in size and simplified. 
     Further, according to the present invention, there is provided an ink supplying method for an ink jet printer that uses an ink supplying system for an ink jet printer described above, the ink supplying method including: an auxiliary connecting means and main tank connecting step of connecting the auxiliary connecting means to each of the another end of the first pipe and the one end of the second pipe and connecting a main tank to the one end of the first pipe; an ink filling step of filling the ink stored in the main tank, into the first pipe, the auxiliary connecting means, the second pipe, and the ink jet head; a vacuum auxiliary connecting step of releasing connection between each of the another end of the first pipe and the one end of the second pipe and the auxiliary connecting means, and connecting the auxiliary tank to each of the another end of the first pipe and the one end of the second pipe, and a vacuum auxiliary tank filling step of filling the auxiliary tank with the ink stored in the main tank. 
     In the present invention, in starting to use the inkjet printer, first, in the auxiliary connecting means, and main tank connection step, the another end of the first pipe and the one end of the second pipe are connected to the auxiliary connecting means, and the main tank filled with the ink with the air therein being eliminated is connected to the one end of the first pipe. The internal volume of the auxiliary connecting means is smaller than that of the auxiliary tank, and hence the ink can be easily filled in the auxiliary connecting means. Therefore, when the ink stored in the main tank is filled in the next ink filling step, the air in the first pipe, the auxiliary connecting means, the second pipe, and the ink jet head are pushed out in this order. Therefore, it is possible to fill the ink while preventing the air from entering the first pipe, the auxiliary connecting means, the second pipe, and the ink jet head. 
     Next, in the vacuum auxiliary tank connecting step, the connection between each of the another end of the first pipe and the one end of the second pipe and the auxiliary connecting means by the detachable unit is released, and each of the another end of the first pipe and the one end of the second pipe and the auxiliary tank, from which the air is eliminated, are connected by the detachable unit. Finally, in the vacuum auxiliary tank filling step, the ink stored in the main tank is supplied into the auxiliary tank. 
     The detachable unit can be connected to or separated from the auxiliary tank or the auxiliary connecting means without allowing the air to flow into the auxiliary tank or the auxiliary connecting means. Therefore, it is possible to fill the ink and prepare for printing while preventing the air from entering the first pipe, the auxiliary tank, the second pipe, and the ink jet head from the main tank. Therefore, the removing of bubbles contained in the ink, which was conventionally performed by the on-off valve provided to the tube provided in the auxiliary tank is unnecessary. Therefore, the ink supply work in starting to use the ink supplying system of the ink jet printer can be facilitated. 
     Further, the tube and the on-off valve provided in the conventional auxiliary tank are unnecessary. Therefore, the configuration of the entire ink supplying system of the ink jet printer can be reduced in size and simplified. 
     Further, according to the present invention, there is provided an ink supplying method for an ink jet printer that uses an ink supplying system for an ink jet printer described above, the ink supplying method including: an auxiliary connecting means and main tank connecting step of connecting the auxiliary connecting means to each of the another end of the first pipe and the one end of the second pipe and connecting the main tank to the one end of the first pipe; an ink filling step of filling the ink stored in the main tank, into the first pipe, the auxiliary connecting means, the second pipe, and the ink jet head; and a filled auxiliary tank connecting step of releasing connection between each of the another end of the first pipe and the one end of the second pipe and the auxiliary connecting means and connecting the auxiliary tank filled with the ink, with the air therein being eliminated, to the another end of the first pipe and the one end of the second pipe. 
     In the present invention, in starting to use the inkjet printer, first, in the auxiliary connecting means, and main tank connection step, the another end of the first pipe and the one end of the second pipe are connected to the auxiliary connecting means, and the main tank filled with the ink with the air therein being eliminated is connected to the one end of the first pipe. The internal volume of the auxiliary connecting means is smaller than that of the auxiliary tank, and hence the ink can be easily filled in the auxiliary connecting means. Therefore, when the ink stored in the main tank is filled in the next ink filling step, the air in the first pipe, the auxiliary connecting means, the second pipe, and the ink jet head are pushed out in this order. Therefore, it is possible to fill the ink while preventing the air from entering the first pipe, the auxiliary connecting means, the second pipe, and the ink jet head. 
     Next, in the filled auxiliary tank connecting step, the connection between each of the another end of the first pipe and the one end of the second pipe and the auxiliary connecting means by the detachable unit is released, and each of the another end of the first pipe and the one end of the second pipe and the auxiliary tank, from which the air is eliminated and which is filled with the air, are connected by the detachable unit. Finally, in the vacuum auxiliary tank filling step, the ink stored in the main tank is supplied into the auxiliary tank. 
     The detachable unit can be connected to or separated from the auxiliary tank or the auxiliary connecting means without allowing the air to flow into the auxiliary tank or the auxiliary connecting means. Therefore, it is possible to fill the ink and prepare for printing while preventing the air from entering the first pipe, the auxiliary tank, the second pipe, and the ink jet head from the main tank. Therefore, the ink supply work in starting to use the ink supplying system of the ink jet printer can be facilitated. 
     Since the auxiliary tank filled with the ink with the air therein being eliminated is used, the ink jet printer can be used without filling the ink into the auxiliary tank in a later step. 
     Further, the tube and the on-off valve provided in the conventional auxiliary tank are unnecessary. Therefore, the configuration of the entire ink supplying system of the ink jet printer can be reduced in size and simplified. 
     Further, according to the present invention, there is provided an ink supplying method for an ink jet printer including: a first pipe having one end which is connected to a first main tank in which first ink is stored with air therein being eliminated; a second pipe having one end which is connected to a first auxiliary tank filled with the first ink with air therein being eliminated and connected to another end of the first pipe; an air lead-in valve that is provided in the second pipe and switches lead-in and blocking of the air into the second pipe; and an ink jet head that is connected to the another end of the second pipe and ejects the first ink, the ink jet printer performing printing on a printing medium with the first ink ejected from the ink jet head, the ink supplying method, including: a first auxiliary connecting means connecting step of releasing connection between each of the another end of the first pipe and the one end of the second pipe and the first auxiliary tank, and connecting the another end of the first pipe and the one end of the second pipe to a first auxiliary connecting means having a connection pipe that directly connects a connecting section with the another end of the first pipe and a connecting section with the one end of the second pipe; a first ink main tank storing step of leading the air into at least the second pipe from the air lead-in valve; a first and second auxiliary connecting means replacing step of releasing connection between each of the another end of the first pipe and the one end of the second pipe and the first auxiliary connecting means, and connecting the another end of the first pipe and the one end of the second pipe to a second auxiliary connecting means having a connection pipe that directly connects the connecting section with the another end of the first pipe and the connecting section with the one end of the second pipe; a first and second main tanks replacing step of releasing connection between the one end of the first pipe and the first main tank, and connecting the one end of the first pipe and a second main tank in which second ink is stored with air therein being eliminated; a second ink filling step of filling the second ink stored in the second main tank into the first pipe, the connection pipe of the second auxiliary connecting means, the second pipe, and the ink jet head; and a second auxiliary tank connecting step of releasing connection between each of the another end of the first pipe and the one end of the second pipe and the second auxiliary connecting means without allowing the air to flow into the first pipe, the second pipe, and the second auxiliary connecting means, and connecting the another end of the first pipe and the one end of the second pipe to a second auxiliary tank, which is filled with the second ink with air therein being eliminated, without allowing the air to flow into the first pipe, the second pipe, and the second auxiliary tank. 
     Before a type of the ink ejected from the ink jet head is changed, the first pipe, the second pipe, and the ink jet head are filled with the first ink. 
     According to the present invention, in changing a type of the ink ejected from the ink jet head, first, in the first auxiliary connecting means connecting step, the connection between each of the another end of the first pipe and the one end of the second pipe and the first auxiliary tank is released, and the another end of the first pipe and one end of the second pipe are connected to the first auxiliary connecting means. The connection pipe in the first auxiliary connecting means is configured to directly connect the two connecting sections, and hence the air in the first ink in the connection pipe tends to leak. Therefore, next, in the first ink main tank storing step, at least a part of the first ink in the second pipe can be stored in the first main tank by leading the air into at least the second pipe from the air lead-in valve. 
     Next, in the first and second auxiliary connecting means replacing step, the connection between each of the another end of the first pipe and the one end of the second pipe and the first auxiliary connecting means is released and the another end of the first pipe and the one end of the second pipe are connected to the second auxiliary connecting means. In the first and second main tanks replacing step, the connection between the one end of the first pipe and the first main tank is released and the one end of the first pipe and the second main tank are connected. 
     In the second ink supplying step subsequently performed, the second ink stored in the second main tank is filled into the first pipe, the connection pipe of the second auxiliary connecting means, the second pipe, and the ink jet head. The connection pipe in the second auxiliary connecting means is configured to directly connect the two connecting sections, and hence the air in the connection pipe tends to leak when the second ink is filled. Therefore, in a state in which the second auxiliary connecting means is connected to the another end of the first pipe and the one end of the second pipe, if the second ink stored in the second main tank is led from the first pipe, it is possible to fill the first pipe, the connection pipe, the second pipe, and the ink jet head without letting the air into the same. 
     When the second ink is filled, the first ink stored in the first pipe, the second pipe, and the ink jet head is discharged from the ink jet head side and discarded. At least a part of the first ink in the second pipe is stored in the first main tank in advance, and hence an amount of the ink to be discarded can be controlled. 
     Finally, in the second auxiliary tank connecting step, the connection between each of the another end of the first pipe and the one end of the second pipe and the second auxiliary connecting means is released without allowing the air to flow into the first pipe, the second pipe, and the second auxiliary connecting means. The another end of the first pipe and the one end of the second pipe are connected to the second auxiliary tank without allowing the air to flow into the first pipe, the second pipe, and the second auxiliary tank. Consequently, the second main tank, the first pipe, the second auxiliary tank, the second pipe, and the ink jet head can be filled with the second ink without letting the air to flow into the same. 
     Further, at least a part of the first ink in the second pipe is stored in the first main tank in advance, and hence it is possible to control an amount of the first ink mixed in the second ink when the second ink is filled into the second pipe. Therefore, the mixing of the first ink in replacing the first ink with the second ink can be reduced and the inks can be more surely replaced. 
     According to the present invention, it is possible to provide an ink supplying system for an ink jet printer, an ink supplying method for an ink jet printer, and an ink jet printer with which ink supply work in starting to use the ink jet printer is easy and that can be reduced in size. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the accompanying drawings: 
         FIG. 1  is a front view illustrating an ink jet printer according to a first embodiment of the present invention; 
         FIG. 2  is a configuration diagram of a carriage unit that configures the ink jet printer illustrated in  FIG. 1 ; 
         FIG. 3  is a block diagram of the ink jet printer according to the first embodiment of the present invention; 
         FIG. 4  is a configuration diagram of an ink supplying system of the ink jet printer according to the first embodiment of the present invention; 
         FIG. 5  is an explanatory diagram of configurations and actions of a valve unit main body and a joint member of the ink jet printer according the first embodiment of the present invention; 
         FIG. 6  is an explanatory diagram of the configurations and the actions of the valve unit main body and the joint member of the ink jet printer according to the first embodiment of the present invention; 
         FIG. 7  is a flowchart of an ink supplying method for the ink supplying system of the ink jet printer according to the first embodiment of the present invention; 
         FIG. 8  is an explanatory diagram illustrating steps of the ink supplying method for the ink supplying system of the ink jet printer according to the first embodiment of the present invention; 
         FIG. 9  is an explanatory diagram illustrating steps of the ink supplying method for the ink supplying system of the ink jet printer according to the first embodiment of the present invention; 
         FIG. 10  is an explanatory diagram illustrating steps of the ink supplying method for the ink supplying system of the ink jet printer according to the first embodiment of the present invention; 
         FIG. 11  is an explanatory diagram illustrating steps of the ink supplying method for the ink supplying system of the ink jet printer according to the first embodiment of the present invention; 
         FIG. 12  is an explanatory diagram illustrating steps of the ink supplying method for the ink supplying system of the ink jet printer according to the first embodiment of the present invention; 
         FIG. 13  is a configuration diagram of a conventional ink supplying system illustrated as a comparative example; 
         FIG. 14  is a configuration diagram of an ink supplying system of the ink jet printer according to the second embodiment of the present invention; 
         FIG. 15  is a flowchart of an ink supplying method for the ink supplying system of the ink jet printer according to the second embodiment of the present invention; 
         FIG. 16  is an explanatory diagram illustrating steps of the ink supplying method for the ink supplying system of the ink jet printer according to the second embodiment of the present invention; 
         FIG. 17A  is an explanatory diagram illustrating a modification of the embodiment of the ink jet printer according to the present invention; 
         FIG. 17B  is an explanatory diagram of a dummy sub-tank used in the modification of the embodiment of the ink jet printer according to the present invention; 
         FIG. 18A  is a configuration diagram of an ink supplying system of the ink jet printer according to a third embodiment of the present invention; 
         FIG. 18B  is an explanatory diagram for describing a first dummy sub-tank  107  used in the third embodiment of the present invention; 
         FIG. 18C  is an explanatory diagram for describing a second dummy sub-tank  108  used in the third embodiment of the present invention; 
         FIG. 18D  is an explanatory diagram for describing a second sub-tank used in the third embodiment of the present invention; 
         FIG. 18E  is an explanatory diagram for describing a second cartridge used in the third embodiment of the present invention; 
         FIG. 19  is a flowchart of an ink supplying method for the ink supplying system of the ink jet printer according to the third embodiment of the present invention; 
         FIG. 20  is a flowchart of an ink supplying method for the ink supplying system of the ink jet printer according to the third embodiment of the present invention; 
         FIG. 21  is a flowchart of an ink supplying method for the ink supplying system of the ink jet printer according to the third embodiment of the present invention; 
         FIG. 22  is a flowchart of an ink supplying method for the ink supplying system of the ink jet printer according to the third embodiment of the present invention; 
         FIG. 23  is a flowchart of an ink supplying method for the ink supplying system of the ink jet printer according to the third embodiment of the present invention; 
         FIG. 24  is a flowchart of an ink supplying method for the ink supplying system of the ink jet printer according to the third embodiment of the present invention; 
         FIG. 25  is an explanatory diagram of an ink supplying system of the ink jet printer according to the first modification of the present invention; 
         FIG. 26  is a flowchart of an ink supplying method for the ink supplying system of the ink jet printer according to the first modification of the present invention; 
         FIG. 27  is an explanatory diagram illustrating steps of the ink supplying method for the ink supplying system of the ink jet printer according to the first modification of the present invention; 
         FIG. 28  is an explanatory diagram illustrating steps of the ink supplying method for the ink supplying system of the ink jet printer according to the first modification of the present invention; 
         FIG. 29  is an explanatory diagram illustrating steps of the ink supplying method for the ink supplying system of the ink jet printer according to the first modification of the present invention; 
         FIG. 30  is an explanatory diagram illustrating steps of the ink supplying method for the ink supplying system of the ink jet printer according to the first modification of the present invention; 
         FIG. 31  is an explanatory diagram illustrating steps of the ink supplying method for the ink supplying system of the ink jet printer according to the second modification of the present invention; 
         FIG. 32  is an explanatory diagram illustrating steps of the ink supplying method for the ink supplying system of the ink jet printer according to the second modification of the present invention; 
         FIG. 33  is an explanatory diagram illustrating steps of the ink supplying method for the ink supplying system of the ink jet printer according to the second modification of the present invention; 
         FIG. 34  is an explanatory diagram illustrating steps of the ink supplying method for the ink supplying system of the ink jet printer according to the second modification of the present invention; 
         FIG. 35  is a flowchart of an ink supplying method for the ink supplying system of the ink jet printer according to the third modification of the present invention; 
         FIG. 36  is an explanatory diagram illustrating steps of the ink supplying method for the ink supplying system of the ink jet printer according to the third modification of the present invention; and 
         FIG. 37  is an explanatory diagram illustrating steps of the ink supplying method for the ink supplying system of the ink jet printer according to the third modification of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Embodiment 
     A first embodiment of the present invention is described in detail below with reference to the accompanying drawings.  FIGS. 1 to 12  are explanatory diagram of an ink jet printer according to a first embodiment of the present invention.  FIG. 1  is a front view of the ink jet printer,  FIG. 2  is a configuration diagram of a carriage unit illustrated in  FIG. 1 , and  FIG. 3  is a block diagram. 
     An ink jet printer  1  according to this embodiment schematically includes, as illustrated in  FIG. 1 , conveying means  2  that conveys recording sheet P as a printing medium in a conveying direction L 1  determined in advance (direction perpendicular to a paper surface in  FIG. 1 ), a carriage unit  4  that reciprocatingly moves a plurality of ink jet heads  58 , which jet inks W having colors different from one another and perform printing on the recording sheet P, in an orthogonal direction L 2  orthogonal to the conveying direction L 1 , a plurality of sub-tanks  52  that are connected to the plurality of ink jet heads  58 , respectively, and from which the inside air is eliminated, cartridges  51  that are connected to the plurality of sub-tanks  52 , respectively, and in which the inks W are stored with the inside air eliminated, and a main control unit  46  that controls the components. 
     As disclosed herein, each of the sub-tanks  52  corresponds to an auxiliary tank (primary auxiliary ink tank) and each of the cartridges  51  corresponds to a main tank (main ink tank). 
     In short, this ink jet printer  1  is an ink jet printer that moves, while conveying the recording sheet P in the conveying direction L 1 , the ink jet heads  58  in the orthogonal direction L 2  orthogonal to the conveying direction L 1  and records characters, images, and the like on the recording sheet P. In this embodiment, as an example, the ink jet printer  1  includes six ink jet heads  58  and ejects the inks W of black (Bk), cyan (C), magenta (M), yellow (Y), light magenta (Lm), and light cyan (Lc). Those six ink jet heads  58  are configured the same. 
     The carriage unit  4  is a unit that reciprocatingly moves, along the orthogonal direction L 2 , on the recording sheet P conveyed in a state in which the recording sheet P is placed on an upper surface of a platen  12  heated by a heater  11 . As illustrated in  FIGS. 1 and 2 , the carriage unit  4  includes a carriage  7  and moving means  9 . 
     Nozzle holes  58   a  for ejecting the inks Ware provided in nozzle surfaces  58   b  on lower surfaces of the ink jet heads  58 , respectively. As illustrated in  FIG. 2 , the ink jet heads  58  are fixed to a head base  7   a  of the carriage  7  in a state in which the nozzle surfaces  58   b  of the ink jet heads  58  are opposed to the recording sheet P. In this case, the ink jet heads  58  are fixed such that the plurality of nozzle holes  58   a  are arranged along the conveying direction L 1 . The six ink jet heads  58  are fixed to the head base  7   a  to be arranged in the orthogonal direction L 2  in which the carriage  7  moves. 
     As illustrated in  FIG. 1 , the ink jet heads  58  are connected to the sub-tanks  52  through an intermediation of second pipes  54 , respectively. The sub-tanks  52  are connected to the cartridges  51  through an intermediation of first pipes  53 , respectively. 
     Each of the second pipes  54  is a long tube made of a soft material and having flexibility such that the second pipe  54  does not affect the movement of the carriage  7 . 
     As illustrated in  FIG. 1 , the carriage  7  is movably fixed on a carriage rail (not shown) fixed to a base  30  in a state in which the carriage rail is arranged along the orthogonal direction L 2 . The carriage  7  is coupled to a conveyor belt  32  wound around a pair of pulleys  31 . One pulley  31  of the pair of pulleys  31  rotates according to a rotational driving force from a driving motor  33  fixed to the base  30 . The other pulley (not shown) rotates following the conveyor belt  32 . Consequently, the carriage  7  can reciprocatingly move in the orthogonal direction L 2 . 
     That is, the carriage rail, the pair of pulleys  31 , the conveyor belt  32 , and the driving motor  33  constitute the moving means  9 . 
     Conveying rollers  34  are provided on the base  30  along the orthogonal direction L 2 . The conveying rollers  34  include one lower roller (not shown) located on a lower side of the recording sheet P and a plurality of upper rollers (not shown) located on an upper side of the recording sheet P. The lower roller is driven to rotate by a motor (not shown). The upper rollers function as pinch rollers that press the recording sheet P and rotate following the conveyance of the recording sheet P. In other words, the conveying rollers  34  are driven by the motor (not shown) and rotate in opposite directions in a state in which the conveying rollers  34  pinch the recording sheet P therebetween. Consequently, the recording sheet P is conveyed in the conveying direction L 1 . In other words, the conveying rollers  34  function as the conveying means  2 . 
     The platen  12  incorporating the heater  11  is arranged on a lower surface of the recording sheet P. This platen  12  includes an absorbing mechanism (not shown). Consequently, the recording sheet P slides while sticking to an upper surface of the platen  12  and is conveyed by the conveying rollers  34 . 
     The plurality of sub-tanks  52  are detachably attached to a sub-tank attaching unit  22  (second attaching unit). The plurality of cartridges  51  are detachably attached to a cartridge attaching unit  21  (first attaching unit). The sub-tank attaching unit  22  and the cartridge attaching unit  21  are fixed on the base  30 . 
     That is, an operator of the ink jet printer  1  can easily replace the sub-tanks  52  and the cartridges  51  according to a remaining amount and a period of use of the sealed inks W. In this case, the sub-tanks  52  are arranged below the nozzle holes  58   a , i.e., downward in the vertical direction such that a predetermined negative pressure is applied to the nozzle holes  58   a . The cartridges  51  are arranged further below the sub-tanks  52 . 
     Dummy sub-tanks  59  described later can be detachably attached to the sub-tank attaching unit  22  by replacing the sub-tanks  52 . 
     A suction unit  40  and a wipe unit  41  are provided on the base  30 . The suction unit  40  is provided in a position where the carriage  7  stays on standby away from an upper region (printing region) of the recording sheet P, i.e., a home position. The suction unit  40  includes suction caps  40   a  and a suction pump  40   b . When the carriage  7  is arranged in the home position, the respective suction caps  40   a  come into contact with the respective nozzle surfaces  58   b  of the ink jet heads  58 . 
     The suction pump  40   b  is a pump that forcibly performs suction in the nozzle holes  58   a  from the ink jet heads  58  side of an ink supplying system  50  described later to discharge the inks W. Consequently, when the nozzle holes  58   a  clog up because of some cause, suction can be performed in the home position to solve the clogging in the nozzle holes  58   a  by the forcible discharge of the inks W. The discharged inks W are collected in a waste liquid tank  40   c  connected to the suction pump  40   b.    
     The wipe unit  41  is provided between the recording sheet P and the suction unit  40 . The wipe unit  41  has an elastic or porous wipe section  41   a  that comes into contact with the nozzle surfaces  58   b  and wipes the nozzle surfaces  58   b  to remove dirt and the like when the wipe unit  41  operates. Consequently, the nozzle surfaces  58   b  of the ink jet heads  58  are maintained in as clean a state as possible. 
     As illustrated in  FIG. 3 , the main control unit  46  provided to the inkjet printer  1  includes a CPU  46   a  that controls an arithmetic operation and the entire system on the basis of a predetermined control program, a ROM  46   b  that stores therein the control program for the CPU  46   a  and the like in a predetermined region, a RAM  46   c  for storing data read out from the ROM  46  band the like and an arithmetic operation result necessary in an arithmetic operation process of the CPU  46   a , heater energizing means  46   d  for energizing the heater  11 , driving-motor driving means  46   e  for driving the driving motor  33 , and suction-pump driving means  46   f  for driving the suction pump  40   b.    
     The CPU  46   a  is connected to the ROM  46   b , the RAM  46   c , the heater energizing means  46   d , the driving-motor driving means  46   e , the suction-pump driving means  46   f , and an ink control device  61   a  of an ink-supply control unit  61  described later. 
     The CPU  46   a  is further connected to an input and output panel  47 . A user can obtain information from the CPU  46   a  and output various commands to the CPU  46   a  via the input and output panel  47 . 
     The ink jet printer  1  includes six sets of ink supplying systems  50  for the inks of W six colors. One set of the ink supplying systems  50  illustrated in  FIG. 4  is described as an example. 
     As illustrated in  FIGS. 3 and 4 , the ink supplying system  50  includes a first pipe  53  having one end  53   a  which is connected to the cartridge  51 , a second pipe  54  having one end  54   a  which is connected to the sub-tank  52  connected to the another end  53   b  of the first pipe  53 , an ink jet head  58  that is connected to the another end  54   b  of the second pipe  54  and ejects ink to perform printing on the recording sheet P, sub-tank detecting means  63  (second detecting means) fixed to the sub-tank attaching unit  22 , cartridge detecting means  62  (first detecting means fixed to the cartridge attaching unit  21 , and the ink-supply control unit  61  that controls the components according to commands from the main control unit  46 . 
     When ink is supplied by the ink supplying system  50 , the cartridge  51 , the sub-tank  52 , and the dummy sub-tank  59  used in replacement of the sub-tank  52  are used. 
     As disclosed herein, the dummy sub-tank  59  corresponds to the auxiliary connecting means (secondary auxiliary ink tank). 
     The sub-tank detecting means  63  and the cartridge detecting means  62  include contact sensors. The sub-tank detecting means  63  detects whether or not the sub-tank  52  or the dummy sub-tank  59  is attached to the sub-tank attaching unit  22 . The cartridge detecting means  62  detects whether or not the cartridge  51  is attached to the cartridge attaching unit  21 . 
     The sub-tank detecting means  63  and the cartridge detecting means  62  transmit detection results to the ink control device  61   a.    
     The cartridge  51  includes a cartridge case  51   a  made of a resin molded in a box shape, a cartridge bag  51   b  that is arranged in the inside of the cartridge case  51   a , eliminates the air in the inside, and stores the ink W, and a cartridge connecting section  51   c  serving as an inlet and an outlet of the ink W to and from the cartridge bag  51   b.    
     On the other hand, the sub-tank  52  includes a sub-tank case  52   a  made of a resin molded in a box shape, a sub-tank bag  52   b  that is arranged in the inside of the sub-tank case  52   a  and can be filled with the ink W, in which a vacuum is drawn in the inside thereof in advance, and two valve unit main bodies  80  connected to the another end  53   b  of the first pipe  53  and the one end  54   a  of the second pipe  54 , respectively. The valve unit main bodies  80  are described in detail later. 
     A portion between the sub-tank bag  52   b  and each of the two valve unit main bodies  80  is sealed to prevent the ink W and the air from entering and leaking from the portion. The two valve unit main bodies  80  serve as inlets and outlets when the ink W flows in from and flows out to the sub-tank bag  52   b , and are attached to one side of the sub-tank case  52   a.    
     Joint members  90  are respectively provided at the another end  53   b  of the first pipe  53  and the one end  54   a  of the second pipe  54  connected to the valve unit main bodies  80 . The joint members  90  function as detachable units configured not to allow the air to flow in to the valve unit main bodies  80  side when the pipes are connected to the valve unit main bodies  80 . 
     The dummy sub-tank  59  includes a dummy sub-tank case  59   a  made of a resin molded in a box shape same as the shape of the sub-tank case  52   a , two valve unit main bodies  80  connected to the another end  53   b  of the first pipe  53  and the one end  54   a  of the second pipe  54 , respectively, and a U-shaped connection pipe  59   b  which is molded by a resin or the like and directly connects the two valve unit main bodies  80 . The two valve unit main bodies  80  are attached to one side of the dummy sub-tank case  59   a  in the same manner as the sub-tank  52 . 
     It is preferable that the dummy sub-tank  59  be connected to the first pipe  53  or the second pipe  54  and configured not to prevent a flow of ink when an ink channel is formed. It is also preferable that the dummy sub-tank  59  be configured to have an extremely small ink volume that can present therein when compared with the sub-tank  52 . The ink volume that can present in the sub-tank  52  means an ink volume that can fill the sub-tank bag  52   b . The ink volume that can present in the dummy sub-tank  59  means an ink volume that can present in the connection pipe  59   b . Moreover, it is preferable that the ink volume that can be present in the dummy sub-tank  59  be equal to or smaller than 1/10 of that in the sub-tank  52  as a reference. 
     The connection pipe  59   b  can be prevented from being an obstacle of the flow of ink by being formed of a pipe having a sectional area same as that of the first pipe  53  or the second pipe  54 . The connection pipe  59   b  may be formed of a pipe same as the first pipe  53  or the second pipe  54 . 
     When the sub-tank  52  is attached to the sub-tank attaching unit  22 , the joint members  90  provided at the another end  53   b  of the first pipe  53  and the one end  54   a  of the second pipe  54  and the two valve unit main bodies  80  provided in the sub-tank  52  are connected to each other. When the sub-tank  52  is removed from the sub-tank attaching unit  22 , the connection between the joint members  90  provided at the another end  53   b  of the first pipe  53  and the one end  54   a  of the second pipe  54  and the two valve unit main bodies  80  provided in the sub-tank  52  is released. 
     The same holds true for the dummy sub-tank  59  that is used by replacing the sub-tank attaching unit  22 . That is, when the dummy sub-tank  59  is attached to the sub-tank attaching unit  22 , the joint members  90  provided at the another end  53   b  of the first pipe  53  and the one end  54   a  of the second pipe  54  and the two valve unit main bodies  80  provided in the dummy sub-tank  59  are connected to each other. When the dummy sub-tank  59  is removed from the sub-tank attaching unit  22 , the connection between the joint members  90  provided at the another end  53   b  of the first pipe  53  and the one end  54   a  of the second pipe  54  and the two valve unit main bodies  80  provided in the sub-tank  59  is released. 
     When the cartridge  51  is attached to the cartridge attaching unit  21 , the one end  53   a  of the first pipe  53  and the cartridge connecting unit  51   c  of the cartridge  51  are connected to each other. When the cartridge  51  is removed from the cartridge attaching unit  21 , the connection between the one end  53   a  of the first pipe  53  and the cartridge connecting unit  51   c  is released. 
     It is also possible that the joint member  90  is provided at the one end  53   a  of the first pipe  53  and the valve unit main body  80  is used instead of the cartridge connecting unit  51   c  to perform connection and separation in the same manner as described above. 
     The cartridge bag  51   b  of the cartridge  51  and the sub-tank bag  52   b  of the sub-tank  52  are made of a thin polyethylene bag or the like, on the surface of which aluminum is deposited, and have flexibility. The ink W can be pushed out by pressing the cartridge bag  51   b  and the sub-tank bag  52   b  with a hand. 
     The dummy sub-tank case  59   a  is provided to form an external appearance of the dummy sub-tank  59  same as that of the sub-tank  52 . The dummy sub-tank case  59   a  may not be used or may be reduced in size. 
     A supply pump  60  is arranged in a route of the first pipe  53  and generates a driving force for carrying the ink W stored in the cartridge  51  to the first pipe  53 . The supply pump  60  can switch open and closed states of the route in which the ink W of the first pipe  53  flows. 
       FIGS. 5 and 6  are explanatory diagrams of configurations and operations of the valve unit main body  80  and the joint member  80 . 
       FIG. 5  is a diagram illustrating a state in which the valve unit main body  80  and the joint member  80  are separated from each other.  FIG. 6  is a diagram illustrating a state in which the valve unit main body  80  and the joint member  90  are connected to each other. 
     The valve main body  80  generally includes, as illustrated in  FIG. 5 , a valve seat  82 , a valve element  83  closely fitted to the valve seat, an urging spring  84  that urges the valve element  83  toward the valve seat  82 , and a valve main body  85  that houses the valve seat  82 , the valve element  83 , and the urging member  84 . 
     A fitting hole  82   a  is provided in the center of the valve seat  82  such that the valve seat  82  is generally formed in a substantially ring shape. This valve seat  82  is made of a resin that is elastically deformable when being pressed. The fitting hole  82   a  is a hole for fitting a distal end  91   a  of the joint member  90  described later therein. On an inner peripheral surface of the valve seat  82  opposed to this fitting hole  82   a , two contact projecting sections  82   b  and  82   c , which project inward over a circumferential direction, are vertically provided side by side. 
     The valve element  83  is formed in a substantially bottomed cylindrical shape including a sidewall section  83   a  formed in a cylindrical shape and a bottom section  83   b  formed to close one end side peripheral edge of this sidewall section  83   a . At an edge where the sidewall section  83   a  and the bottom section  83   b  are connected, a tapered surface edge  83   c  inclined with respect to the bottom section  83   b  is provided. A diameter D 2  of the bottom section  83   b  including this tapered surface edge  83   c  (which coincides with an outer diameter of the sidewall section  83   a ) is set larger than a diameter D of the fitting hole  82   a  provided in the valve seat  82 . This valve element  83  is arranged with the bottom section  83   b  directed to the valve seat  82  side. The urging spring  84  is provided in the inside of this valve element  83 . This urging spring  84  is arranged in the inside of this valve element  83  such that one end of the urging spring  84  comes into contact with a surface of the bottom section  83   b  on an internal side and the another end thereof comes into contact with a Step  85   e  described later in the inside of the valve main body  85 . Consequently, the urging spring  84  supports the valve element  83  such that the valve element  83  can be brought close to or separated from the valve seat  82 , and urges the valve element  83  toward the valve seat  82 . 
     A moving distance R in which this valve element  83  can be brought close to or separated from the valve seat  82  (hereinafter referred to as “valve element moving distance”) is a distance in which the valve element  83  moves from a state illustrated in  FIG. 5  in which the bottom section  83   b  and the tapered surface edge  83   c  of the valve element  83  are in contact with the contact projecting section  82   c  of the valve seat  82  while pressing the contact projecting section  82   c  upward to a state illustrated in  FIG. 6  in which an opening end  83   d  of the valve element  83  is in contact with the Step  85   e.    
     Small holes (not shown) are provided in the sidewall section  83   a  of the valve element  83 . Even if the opening end  83   d  comes into contact with the Step  85   e , the ink W can flow through the small holes. 
     The valve main body  85  houses the valve seat  82 , the valve element  83 , the urging spring  84 , and the ink W described above such that the ink W can flow in and out. The valve main body  85  is formed to be opened on both upper and lower sides and is formed in a substantially cylindrical shape formed as if cylinders having three kinds of different diameters, which decrease one after another from large to medium and small, are coupled. In a valve seat housing cylinder section  85   a  formed by this large-diameter cylinder, the valve seat  82  described above is pressed and fitted thereto. 
     In a valve element housing cylinder section  85   b  formed by this medium-diameter cylinder, the valve element  83  and the urging spring  84  described above are housed. An inner diameter of this valve element housing cylinder section  85   b  is set larger than an outer diameter of the valve element  83 . Consequently, a clearance is formed between an inner peripheral surface of this valve element housing cylinder section  85  and an outer peripheral surface of the sidewall section  83   a  of the valve element  83 . The ink W flows in and out through this clearance. The sub-tank bag  52   b , the connection pipe  59   b , and the like are attached to an ink inflow cylinder section  85   c  formed by this small-diameter cylinder. 
     Diameters of the valve seat housing cylinder section  85   a  and the valve element housing cylinder section  85   b  adjacent to each other are different and diameters of the valve element housing cylinder section  85  band the ink inflow cylinder section  85   c  adjacent to each other are different, respectively, and hence steps  85   d  and  85   e  are formed. The valve seat  82 , the valve element  83 , and the urging spring  84  are positioned by those steps  85   d  and  85   e . In other words, the valve seat  82  is in contact with the Step  85   d  and the another end of the urging spring  84  is in contact with the Step  85   e.    
     Consequently, the urging spring  84  urges the valve element  83  toward the valve seat  82 . The urging force of the urging spring  84  in the valve unit main body  80  attached to the sub-tank  52  is determined as described below. That is, the urging force is set to be larger than a total of force applied to the bottom section  83   b  of the valve element  83  by the atmospheric pressure from the direction of the joint member  90  illustrated in  FIG. 5 . 
     This is because it is necessary to keep an inside  86  of the valve main body  85  in a vacuum even if the valve element  83  is subjected to the atmospheric pressure from the direction of the joint member  90 . 
     As illustrated in  FIG. 5 , the joint member  90  is formed in a bottomed cylindrical shape. Specifically, in the joint member  90 , a bottom section  91   a  fitted in the fitting hole  82   a  of the valve main body  80  is provided on a distal end side and an opening section  91   b  connected to the another end  53   b  of the first pipe  53  and the one end  54   a  of the second pipe  54  is provided on a proximal end side. In other words, an inside  92  of this joint member  90  formed in the bottomed cylindrical shape is formed in a cavity shape and ink flows in and out through the inside  92 . In this bottom section  91   a , a tapered section  93  is provided to be tapered toward a distal end thereof. The tapered section  93  is provided in this way, and hence it is easy to fit the joint member  90  in the fitting hole  82   a  at the time of fitting. 
     An outer diameter D 1  of a peripheral wall section  91   c  extending from the distal end to the proximal end of this joint member  90  is set larger than the diameter D of the fitting hole  82   a  provided in the valve seat  82 . Consequently, when the joint member  90  is fitted in the fitting hole  82   a  from an axial direction thereof, the contact projecting sections  82   b  and  82   c  provided on the inner peripheral surface of the valve seat  82  come into close contact with an outer peripheral surface of the peripheral wall section  91   c  of this joint member  90  while pressing the outer peripheral surface to thereby realize a sealed state. 
     A small-diameter ink supply hole  96  for causing the inside  92  to communicate with the outside is provided in the peripheral wall section  91   c  of this joint member  90 . A distance R 1  from the bottom section  91   a  as the distal end is set smaller than the valve element moving distance R and is set larger than the thickness R 2  of the valve seat  82 . Consequently, when the joint member  90  is fitted in the valve main body  80  from the fitting hole  82   a  as illustrated in  FIG. 6 , the ink supply hole  96  is preferably arranged in the inside  86  of the valve main body  85  after climbing over the valve seat  82 . 
     In this way, when the valve unit main body  80  and the joint member  90  are connected to each other as illustrated in  FIG. 6 , the ink W can flow in both directions between the valve unit main body  80  and the joint member  90 . 
     On the other hand, when the valve unit main body  80  and the joint member  90  are separated from each other as illustrated in  FIG. 5 , the valve seat  82  and the valve element  83  come into close contact with each other, and hence the valve unit main body  80  blocks the inflow and the outflow of not only the ink W but also the air. The small-diameter ink supply hole  96  is provided in the joint member  90 . However, whether the ink W and the air flow in and flow out from this ink supply hole  96  depends on a diameter of a hole provided at the another end of the pipe and the like to which the joint member  90  is connected, a water head difference between both ends of the pipe, and the like. Details are described later. 
     As illustrated in  FIG. 3 , the ink-supply control unit  61  includes the ink control device  61   a  that performs various arithmetic operations according to commands from the CPU  46   a , a timer  61   b  that measures a predetermined time and sends a signal to the ink-supply control unit  61 , and supply-pump driving means  61   c  for driving the supply pump  60 . 
     The ink control device  61   a  is connected to the CPU  46   a , the timer  61   b , and the supply-pump driving means  61   c.    
     Next, an ink supplying method in the ink jet printer according to the present invention is described.  FIG. 7  is a flowchart of the ink supplying method.  FIGS. 8 to 12  are explanatory diagrams illustrating respective steps of the ink supplying method. 
     In order to clarify the description of the respective steps of the ink supplying method, only a main part of the ink supplying system  50  is illustrated in the figure and described. One set illustrated in  FIG. 8  among six sets of the ink supplying system  50  provided to the ink jet printer  1  is described as an example. 
     As illustrated in  FIG. 8 , before the ink jet printer  1  is used, nothing is attached to the sub-tank attaching unit  22  and the cartridge attaching unit  21 . This is for the purpose of preventing the ink W in the cartridge  51  from coming into contact with the air to be oxidized or dried and of realizing convenience of transportation of the ink jet printer  1 . 
     The carriage  7  is arranged in the home position in advance by the driving motor  33 . The suction caps  40   a  of the suction unit  40  are in contact with the nozzle surfaces  58   b  of the ink jet heads  58 , respectively. 
     When the ink control device  61   a  of the ink-supply control unit  61  receives a command from the CPU  46   a  of the main control unit  46  to execute an initial filling step for the ink W, first, in an auxiliary connecting means and main tank connecting step (Step S 10 ), the ink control device  61   a  instructs the supply-pump driving means  61   c  to set the supply pump  60  in a closed state. 
     The operator of the ink jet printer  1  attaches the dummy sub-tank  59  to the sub-tank attaching unit  22 . Consequently, the joint member  90  provided at the another end  53   b  of the first pipe  53  and the joint member  90  provided at the one end  54   a  of the second pipe  54 , and the two valve unit main bodies  80  provided in the dummy sub-tank  59  are connected to each other, respectively. The operator connects the cartridge connecting section  51   c , which is provided to the cartridge  51  filled with the ink W with the air therein being eliminated, to the one end  53   a  of the first pipe  53  (see  FIG. 9 ). 
     The ink control device  61   a  detects, with use of the sub-tank detecting means  63 , that the dummy sub-tank  59  is attached to the sub-tank attaching unit  22 . The ink control device  61   a  further detects, with use of the cartridge detecting means  62 , that the cartridge  51  is attached to the cartridge attaching unit  21 . The ink control device  61   a  shifts to Step S 11 . 
     Next, in an ink filling step (Step S 11 ), the ink control device  61   a  instructs the supply-pump driving means  61   c  to set the supply pump  60  in an open state. The ink control device  61   a  instructs the CPU  46   a  to drive the suction pump  40   b  via the suction-pump driving means  46   f  and fill the ink W stored in the cartridge  51  into the first pipe  53 , the connection pipe  59   b , the second pipe  54 , and the ink jet head  58 . The ink control device  61   a  shifts to Step S 12  (see  FIG. 10 ). 
     The connection pipe  59   b  is configured to directly connect the two valve unit main bodies  80 , and hence the air in the connection pipe  59   b  tends to leak when the ink W is filled. Therefore, when the ink W stored in the cartridge  51  is filled, the air in the first pipe  53 , the connection pipe  59   b , the second pipe  54 , and the ink jet head  58  is pushed out in this order. It is possible to fill the first pipe  53 , the connection pipe  59   b , the second pipe  54 , and the ink jet head  58  with the ink W without letting the air into the same. 
     Next, in a vacuum auxiliary tank connecting step (Step S 12 ), the ink control device  61   a  instructs the supply-pump driving means  61   c  to set the supply pump  60  in the closed state. 
     The operator removes the dummy sub-tank  59  from the sub-tank attaching unit  22  and attaches the sub-tank  52  to the sub-tank attaching unit  22 . 
     Consequently, the connection between each of the joint member  90  provided at the another end  53   b  of the first pipe  53  and the joint member  90  provided at the one end  54   a  of the second pipe  54 , and the two valve unit main bodies  80  provided in the dummy sub-tank  59  is released. Moreover, the two joint members  90  and the two valve unit main bodies  80  provided to the sub-tank  52  in which a vacuum is drawn in the inside of the sub-tank bag  52   b  in advance are connected to each other (see  FIG. 11 ). 
     The ink control device  61   a  detects, with use of the sub-tank detecting means  63 , that the sub-tank  52  is attached to the sub-tank attaching unit  22 . The ink control device  61   a  shifts to Step S 13 . 
     The ink supply hole  96  is provided to the joint member  90  provided at the another end  53   b  of the first pipe  53 . However, the air does not flow into the joint member  90  from the another end  53   b  of the first pipe  53  because the connection between the joint members  90  and the valve unit main bodies  80  is released when the supply pump  60  is in the closed state and because the another end  53   b  of the first pipe  53  is arranged at the top of the first pipe  53 . 
     The ink supply hole  96  is provided to the joint member  90  provided at the one end  54   a  of the second pipe  54  and the nozzle hole  58   a  is provided to the ink jet head  58  connected to the another end  54   b  of the second pipe  54 . The nozzle hole  58   a  is arranged above the ink supply hole  96 , and hence the ink W tends to flow from the another end  54   b  side to the one end  54   a  side of the second pipe  54  with own weight thereof. However, the nozzle hole  58   a  is extremely small and the viscosity of the ink W is high, and hence the ink W at the another end  54   b  section cannot flow to the one end  54   a  side. Consequently, the ink W on the one end  54   a  side does not move either and the air does not flow into the second pipe  54 . 
     In this way, even if the connection between the valve unit main bodies  80  and the joint members  90  is released, the air does not flow in from the valve unit main bodies  80  and the joint members  90 . As described above, even if the valve unit main bodies  80  and the joint members  90  are connected to each other, the air does not flow in. 
     In this way, detachable mechanisms are configured by the valve unit main bodies  80 , the joint members  90 , the first pipe  53 , the supply pump  60 , the second pipe  54 , and the ink jet head  58 . It is possible to connect to and separate from each other the another end  53   b  of the first pipe  53  and the one end  54   a  of the second pipe  54 , and the sub-tank  52 , or the another end  53   b  of the first pipe  53  and the one end  54   a  of the second pipe  54 , and the dummy sub-tank  59  without allowing the air to flow into the first pipe  53 , the second pipe  54 , the sub-tank  52 , and the dummy sub-tank  59 . 
     The sub-tank  52  in which a vacuum is drawn in the inside of the connection pipe  59   b  in advance can be used as a common component regardless of a color of the ink W stored in the cartridge  51 . Therefore, types of components necessary for the ink supplying system  50  can be reduced. 
     Finally, in a vacuum auxiliary tank filling step (Step S 13 ), the ink control device  61   a  instructs the supply-pump driving means  61   c  to drive the supply pump  60  and fills the ink W stored in the cartridge  51  into the sub-tank  52  (see  FIG. 12 ). 
     In this way, with the ink jet printer according to the embodiment of the present invention, it is possible to fill the cartridge  51 , the first pipe  53 , the sub-tank  52 , the second pipe  54 , and the ink jet head  58  with the ink W without letting the air into the same and prepare for printing. Therefore, the degassing for the ink conventionally performed by the on-off valve provided to the tube provided in the auxiliary tank is unnecessary. Ink supply work in starting to use the ink jet printer  1  can be facilitated. 
     The tube and the on-off valve provided in the conventional auxiliary tank are unnecessary. Moreover, the dummy sub-tank  59  as a component used for removing the air in the ink supplying system  50  is removed during normal use. Therefore, a configuration of the entire ink supplying system  50  of the ink jet printer can be reduced in size and simplified. 
     A conventional ink supplying system is illustrated in  FIG. 13  as a comparative example. The dummy sub-tank  59  is not provided to the conventional ink supplying system. 
     Therefore, first, a sub-tank  67  is obliquely attached to a sub-tank attaching unit, the air is collected in an upper part of the sub-tank  67 , and the air collected in the upper part is forcibly fed in the direction of an ink jet head  68  together with ink. 
     On the other hand, in this embodiment, as illustrated in  FIG. 12 , the ink supplying system  50  can prevent the inflow of the air, and hence the sub-tank  52  can be horizontally arranged. In the following description, the sub-tank  52  is horizontally arranged and a water head difference is controlled such that all ink in the sub-tank  52 , i.e., ink in a water head difference H 1 +a water head difference H 2  from the nozzle hole  58   a  can be used for printing. In the conventional ink supplying system illustrated in  FIG. 13 , if ink in a range up to the water head difference H 1 +the water head difference H 2  from a nozzle hole can be used for printing in the same manner as this embodiment, the sub-tank  67  is obliquely attached, and hence an amount of unusable ink increases when compared with the sub-tank  52  horizontally attached. That is, ink in a range from a water head difference H 3  to the water head difference H 2  is the unusable ink. Consequently, in the conventional ink supplying system, even usable ink in the sub-tank  52  in the embodiment of the present invention is left in a range A illustrated in  FIG. 13 , i.e., the range from the water head difference H 3  to the water head difference H 2 . 
     Therefore, in the supplying system according to this embodiment, more ink in the sub-tank can be used for printing. 
     Second Embodiment 
     A second embodiment of the present invention is described below.  FIG. 14  is a configuration diagram of an ink supplying system of an ink jet printer. 
     For convenience of description, in the second embodiment of the present invention, components same as those described in the first embodiment are denoted by the same reference symbols and description of the components is omitted. 
     The second embodiment is different from the first embodiment in two points. As a first difference, in the first embodiment, as illustrated in  FIG. 4 , the sub-tank  52  including the sub-tank bag  52   b  in which a vacuum is drawn in advance is used. On the other hand, in the second embodiment, as illustrated in  FIG. 14 , a sub-tank  64  filled with the ink W with the air therein being eliminated is used instead of the sub-tank  52 . 
     That is, in the second embodiment, a sub-tank bag  64   b  provided to the sub-tank  64  is filled with the ink W with the air therein being eliminated. The inflow of the air is prevented by the two valve unit main bodies  80  provided to the sub-tank  64 . The sub-tank  64  includes a sub-tank case  64   a  made of a resin molded in a box shape, the sub-tank bag  64   b  that is arranged in the inside of the sub-tank case  64   a  and filled with the ink W, and the two valve unit main bodies  80 . 
     As a second difference, in the first embodiment, in order to keep the inside of the sub-tank bag  52   b  provided to the sub-tank  52  in a vacuum, a spring having an urging force strong enough for resisting the atmospheric pressure is used as the urging spring  84  provided to the valve unit main body  80 . On the other hand, in the second embodiment, the sub-tank bag  64   b  is filled with the ink W, and hence the urging force of the urging spring  84  may be set weaker than the urging force in the first embodiment. 
     Next, an ink supplying method in the ink jet printer according to the present invention is described.  FIG. 15  is a flowchart of the ink supplying method.  FIG. 16  is an explanatory diagram illustrating steps of the ink supplying method. 
     In the second embodiment, steps up to the ink filling step (Step S 11 ) illustrated in  FIG. 7  are the same as those in the first embodiment and only steps after that are different. 
     As illustrated in  FIG. 15 , in a filled auxiliary tank connecting step (Step S 16 ) performed following the ink filling step (Step S 11 ), in the state illustrated in  FIG. 10 , the operator removes the dummy sub-tank  59  from the sub-tank attaching unit  22  and attaches the sub-tank  64  to the sub-tank attaching unit  22 . 
     Consequently, the connection between each of the joint member  90  provided at the another end  53   b  of the first pipe  53  and the joint member  90  provided at the one end  54   a  of the second pipe  54  and the two valve unit main bodies  80  provided in the dummy sub-tank  59  is released. Moreover, the two joint members  90  and the two valve unit main bodies  80  provided to the sub-tank  64  filled with the ink W with the air therein being eliminated are connected to each other (see  FIG. 16 ). 
     In this way, with the ink jet printer according to the second embodiment of the present invention, the sub-tank  64  filled with the ink W with the air therein being eliminated is used, and hence a step of filling the ink W stored in the cartridge  51  into the sub-tank  64  is unnecessary. Therefore, ink supply work can be performed in a short time. 
     The first embodiment and the second embodiment of the present invention have been described in detail with reference to the drawings. However, a specific configuration is not limited to the embodiments. Changes and the like of the configuration are provided to the present invention without departing from the spirit of the present invention. 
     For example, in the first embodiment, the operator performs the work for attaching the dummy sub-tank  59  to the sub-tank attaching unit  22 , replacing the dummy sub-tank  59  attached to the sub-tank attaching unit  22  with the sub-tank  52 , and attaching the cartridge  51  to the cartridge attaching unit  21 . However, a sub-tank replacing device and a cartridge replacing device that automatically perform the work under the command of the ink-supply control unit  61  may be provided anew. 
     The same configuration can be adopted in the second embodiment as well. 
     In the first embodiment and the second embodiment, the dummy sub-tank  59  including the connection pipe  59   b  that directly connects the two valve unit main bodies  80  is used. However, instead of the connection pipe  59   b , a dummy sub-tank bag that is sealed in sections thereof between the two valve unit main bodies  80 , has a capacity smaller than that of the sub-tank tab  52   b , and has flexibility may be used. 
     The capacity of the dummy sub-tank is smaller than that of the sub-tank  52 , and hence the ink W can be easily filled into the dummy sub-tank  59 . In a state in which the dummy sub-tank is connected to the another end  53   b  of the first pipe  53  and the one end  45   a  of the second pipe  54 , i.e., a state in which the dummy sub-tank bag is used instead of the connection pipe  59   b  of the dummy sub-tank  59  illustrated in  FIG. 9 , the ink W stored in the cartridge  51  is led from the first pipe  53 . Then, it is possible to fill the ink W into the first pipe  53 , the auxiliary connecting means, the second pipe  54 , and the ink jet head  58  while preventing the air from entering the same. 
     The sub-tank detecting means  63  and the cartridge detecting means  62  provided to the ink supplying system  50  in the first embodiment and the second embodiment may be removed. This is because, even if the sub-tank detecting means  63  and the cartridge detecting means  62  are not present, it is possible to detect the sub-tank  52  and the dummy sub-tank  59  attached to the sub-tank attaching unit  22  and the cartridge  51  attached to the cartridge attaching unit  21  by the operator. 
     In the description of the first embodiment and the second embodiment, the respective steps are described on the assumption that, before the ink jet printer  1  is started to be used, the cartridge  51  is not attached to the cartridge attaching unit  21  and the dummy sub-tank  59  is not attached to the sub-tank attaching unit  22 . 
     However, when the cartridge  51  is attached to the cartridge attaching unit  21  and the dummy sub-tank  59  is attached to the sub-tank attaching unit  22  in advance before the ink jet printer  1  is started to be used, it is sufficient to omit the auxiliary connecting means and main tank connecting step (Step S 10 ) and perform the ink filling step (Step S 11 ) and subsequent steps. 
     In the first embodiment and the second embodiment, the suction pump  40   b  is used in order to fill the ink W stored in the cartridge  51  into the first pipe  53 , the connection pipe  59   b , the second pipe  54 , and the ink jet head  58  of the ink supplying system  50  attached with the dummy sub-tank  59 . However, the cartridge bag  51   b  has flexibility, and hence the ink W may be filled into the first pipe  53 , the connection pope  59   b , the second pipe  54 , and the ink jet head  58  by pressing the cartridge case  51   a  in which the ink W is stored without using the suction pump  40   b.    
     In the second embodiment, the two valve unit main bodies  80  are attached to one side of the sub-tank case  64   a  of the sub-tank  64 . 
     However, as illustrated in  FIG. 17A , the valve unit main bodies  80  may be attached to both sides of the sub-tank case  64   a , respectively. 
     In this case, a lid  24  openably and closably attached to the sub-tank attaching unit  22  is provided to the sub-tank attaching unit  22 . The joint member  90  provided at the another end  53   b  of the first pipe  53  is attached to the lid  24 . 
     When the sub-tank  64  is attached to the sub-tank attaching unit  22 , the sub-tank  64  is connected to the one end  54   a  of the second pipe  54 . When the lid  24  is closed, the sub-tank  64  is connected to the another end  53   b  of the first pipe  53 . In this way, the sub-tank  64  is set in an ink supplying system  65 . 
     When the lid  24  is opened, the connection between the sub-tank  64  and the another end  53   b  of the first pipe  53  is released. Therefore, it is preferable that an open and close sensor  25  that detects opening and closing of the lid  24  and issues warming be provided. 
     As illustrated in  FIG. 17B , in a dummy sub-tank  66 , the two valve unit main bodies  80  are attached to both sides of a dummy sub-tank case  66   a  made of a resin molded in a box shape, respectively. A connection pipe  66   b  has a shape of a substantially straight pipe. 
     The same configuration can be adopted in the first embodiment as well. 
     Third Embodiment 
     A third embodiment of the present invention is described below.  FIG. 18A  is a configuration diagram of an ink supplying system of an inkjet printer.  FIG. 18B  is an explanatory diagram for describing a first dummy sub-tank  107  used in the third embodiment of the present invention.  FIG. 18C  is an explanatory diagram for describing a second dummy sub-tank  108  used in the third embodiment of the present invention.  FIG. 18D  is an explanatory diagram for describing a second sub-tank used in the third embodiment of the present invention.  FIG. 18E  is an explanatory diagram for describing a second cartridge used in the third embodiment of the present invention. 
     For convenience of description, in the third embodiment of the present invention, components same as those described in the second embodiment are denoted by the same reference symbols and description of the components is omitted. 
     With an ink supplying system  111  according to this embodiment, ink ejected from the ink jet head  58  can be changed from first ink W 1  to second ink W 2  by a method described below. The first ink W 1  and the second ink W 2  may be different in color or may be the same in color and different in solvent. 
     The ink supplying system  111  is different from the ink supplying system  50  according to the second embodiment illustrated in  FIG. 14  in two points described below. 
     First, in the ink supplying system  111 , the first dummy sub-tank  107  and the second dummy sub-tank  108  are used instead of the dummy sub-tank  59  used in the ink supplying system  50 . 
     The first dummy sub-tank  107  includes a dummy sub-tank case  107   a  made of a resin molded in a box shape same as the shape of a sub-tank case  104   a , two valve unit main bodies  80 , and a U-shaped connection pipe  107   b  made of a resin or the like that directly connects the two valve unit main bodies  80 . 
     Similarly, the second dummy sub-tank  108  includes a dummy sub-tank case  108   a  made of a resin molded in a box shape same as the shape of the sub-tank case  104   a , two valve unit main bodies  80 , and a U-shaped connection pipe  108   b  made of a resin or the like that directly connects the two valve unit main bodies  80 . 
     Second, in the ink supplying system  111 , instead of the second pipe  54  provided to the ink supplying system  50 , there are provided a first divided pipe  55  having one end  55   a  connected to a first sub-tank  104  and having the another end  55   b  at which the joint member  90  is provided, and a second divided pipe  56  having one end  56   a  at which the valve unit main body  80  is provided and having the another end  56   b  connected to the ink jet head  58 . 
     The valve unit main body  80  provided at the one end  56   a  of the second divided pipe  56  and the joint member  90  provided at the another end  56   b  of the first divided pipe  55  correspond to the air lead-in valve in claims. 
     In the third embodiment, the first sub-tank  104  and a second sub-tank  105  are used instead of the sub-tank  64  used in the second embodiment. 
     The first sub-tank  104  is different from the sub-tank  64  in that, whereas filled ink is the ink W in the sub-tank  64 , the filled ink is the first ink W 1  in the first sub-tank  104 . On the other hand, the second sub-tank  105  is different from the sub-tank  64  in that, whereas filled ink is the ink W in the sub-tank  64 , the filled ink is the second ink W 2  in the second sub-tank  105 . 
     That is, the first sub-tank  104  includes the sub-tank case  104   a  made of a resin molded in a box shape, a sub-tank bag  104   b  that is arranged in the inside of the sub-tank case  104  and filled with the first ink W 1 , and the two valve unit main bodies  80 . 
     Similarly, the second sub-tank  105  includes the sub-tank case  105   a  made of a resin molded in a box shape, a sub-tank bag  105   b  that is arranged in the inside of the sub-tank case  105  and filled with the second ink W 2 , and the two valve unit main bodies  80 . 
     In the third embodiment, a first cartridge  101  and a second cartridge  102  are used instead of the cartridge  51  used in the second embodiment. 
     The first cartridge  101  is different from the cartridge  51  in that, whereas stored ink is the ink W in the cartridge  51 , the stored ink is the first ink W 1  in the first cartridge  101 . On the other hand, the second cartridge  102  is different from the cartridge  51  in that, whereas stored ink is the ink W in the cartridge  51 , the stored ink is the second ink W 2  in the second cartridge  102 . 
     That is, the first cartridge  101  includes a cartridge case  101   a  made of a resin molded in a box shape, a cartridge bag  101   b  that is arranged in the inside of the cartridge case  101   a , eliminates the air in the inside, and stores the first ink W 1 , and a cartridge connecting section  101   c  serving as an inlet and an outlet of the first ink W 1  to and from the cartridge bag  101   b.    
     Similarly, the second cartridge  102  includes a cartridge case  102   a  made of a resin molded in a box shape, a cartridge bag  102   b  that is arranged in the inside of the cartridge case  102   a , eliminates the air in the inside, and stores the second ink W 2 , and a cartridge connecting section  102   c  serving as an inlet and an outlet of the second ink W 2  to and from the cartridge bag  102   b.    
     As in the embodiments described above, the sub-tank bag  104   b , the sub-tank bag  105   b , the cartridge bag  101   b , and the cartridge bag  102   b  are made of a thin polyethylene bag or the like, on the surface of which aluminum is deposited, and has flexibility. The ink can be pushed out by pressing the cartridge bags with a hand. 
     Next, an ink supplying method in the ink jet printer according to the present invention is described.  FIG. 19  is a flowchart of the ink supplying method.  FIGS. 20 to 24  are explanatory diagrams illustrating respective steps of the ink supplying step. 
     Note that, in replacing the ink from the first ink W 1  to the second ink W 2 , as illustrated in  FIGS. 18A to 18E , each of the joint member  90  provided at the another end  53   b  of the first pipe  53  and the joint member  90  provided at the one end  55   a  of the first divided pipe  55  and the two valve unit main bodies  80  provided in the first sub-tank  104  are connected. Further, the first cartridge  101  is connected to the one end  53   a  of the first pipe  53 . The joint member  90  provided at the another end  55   b  of the first divided pipe  55  and the valve unit main body  80  provided at the one end  56   a  of the second divided pipe  56  are connected. Further, the first pipe  53 , the first divided pipe  55 , the second divided pipe  56 , and the ink jet head  58  are filled with the first ink W 1 . 
     When the ink control device  61   a  of the ink-supply control unit  61  receives a command from the CPU  46   a  of the main control unit  46  to replace the ink, first, in a first auxiliary connecting means connecting step (Step S 21 ), the ink control device  61   a  instructs the supply-pump driving means  61   c  to set the supply pump  60  in a closed state. 
     An operator of the ink jet printer releases the connection between each of the joint member  90  provided at the another end  53   b  of the first pipe  53  and the joint member  90  provided at the one end  55   a  of the first divided pipe  55  and the two valve unit main bodies  80  provided in the first sub-tank  104 . Then, the operator connects the two joint members  90  and the two valve unit main bodies  80  provided in the first dummy sub-tank  107  (see  FIG. 20 ). 
     The ink control device  61   a  detects, with the sub-tank detecting means  63 , that the first dummy sub-tank  107  is attached to the sub-tank attaching unit  22 . The ink control device  61   a  further detects, with the cartridge detecting means  62 , that the first cartridge  101  is attached to the cartridge attaching unit  21 . The ink control device  61   a  shifts to Step S 22 . 
     Next, in a first ink main tank storing step (Step S 22 ), the ink control device  61   a  instructs the supply-pump driving means  61   c  to set the supply pump  60  in an open state. 
     The operator temporarily releases the connection between the joint member  90  provided at the another end  55   b  of the first divided pipe  55  and the valve unit main body  80  provided at the one end  56   a  of the second divided pipe  56 , leads the air into the first divided pipe  55  from the joint member  90 , and shifts to Step S 23  (see  FIG. 21 ). 
     Then, at least a part of the first ink W 1  in the first divided pipe  55  and the first pipe  53  is stored in the cartridge bag  101   b  of the first cartridge  101 . 
     An amount of the first ink W 1  stored in the cartridge bag  101   b  is, at the maximum, a total of capacities of the first divided pipe  55  and the first pipe  53 . An amount of ink discarded during ink replacement can be more effectively controlled. 
     Next, in a first and second auxiliary connecting means replacing step (Step S 23 ), the ink control device  61   a  instructs the supply-pump driving means  61   c  to set the supply pump  60  in the closed state. 
     The operator releases the connection between each of the joint member  90  provided at the another end  53   b  of the first pipe  53  and the joint member  90  provided at the one end  55   a  of the first divided pipe  55  and the two valve unit main bodies  80  provided in the first dummy sub-tank  107 . Then, the operator connects the two joint members  90  and the two valve unit main bodies  80  provided in the second dummy sub-tank  108 . 
     Moreover, in a first and second main tanks replacing step (Step S 24 ), the operator releases the connection between the one end  53   a  of the first pipe  53  and the first cartridge  101 , and connects the one end  53   a  of the first pipe  53  and the second cartridge  102  (see  FIG. 22 ). Then, the operator sends a signal representing the end of Step S 24  to the ink control device  61   a  via the input and output panel  47  and shifts to Step S 25 . 
     Next, in a second ink filling step (Step S 25 ), when the ink control device  61   a  detects that Step S 24  ends, the ink control device  61   a  instructs the supply-pump driving means  61   c  to set the supply pump  60  in the open state. Moreover, the ink control device  61   a  drives the suction pump  40   b , fills the second ink W 2  stored in the second cartridge  102  into the first pipe  53 , a connection pipe  108   b  of the second dummy sub-tank  108 , the first divided pipe  55 , the second divided pipe  56 , and the ink jet head  58 , stops the suction pump  40   b , and shifts to Step S 26  (see  FIG. 23 ). 
     The connection pipe  108   b  is configured to directly connect the two valve unit main bodies  80 , and hence the air in the connection pipe  108   b  tends to leak when the second ink W 2  is filled. Therefore, when the second ink W 2  stored in the second cartridge  102  is filled, the air in the first pipe  53 , the connection pipe  108   b , the first divided pipe  55 , the second divided pipe  56 , and the ink jet head  58  is pushed out in this order. It is possible to fill the first pipe  53 , the connection pipe  59   b , the second pipe  54 , and the ink jet head  58  with the second ink W 2  without letting the air to flow into the same. 
     When the second ink W 2  is filled, the first ink W 1  stored in the first pipe  53 , the first divided pipe  55 , the second divided pipe  56 , and the ink jet head  58  is discharged from the ink jet head  58  side and discarded. At least a part of the first ink W 1  in the first divided pipe  55  is stored in the first cartridge  101  in advance, and hence an amount of the first ink W 1  to be discarded can be controlled. 
     Finally, in a second auxiliary tank connecting step (Step S 26 ), the ink control device  61   a  instructs the supply-pump driving means  61   c  to set the supply pump  60  in the closed state. 
     The operator releases the connection between each of the joint member  90  provided at the another end  53   b  of the first pipe  53  and the joint member  90  provided at the one end  55   a  of the first divided pipe  55  and the two valve unit main bodies  80  provided to the second dummy sub-tank  108 . Then, the operator connects the two joint members  90  and the two valve unit main bodies  80  provided to the second sub-tank  105  (see  FIG. 24 ). 
     At least a part of the first ink W 1  in the first divided pipe  55  is stored in the first cartridge  101  in advance, and hence it is possible to control an amount of the first ink W 1  mixed in the second ink W 2  when the second ink W 2  is supplied into the first divided pipe  55 . Therefore, it is possible to reduce the mixing of the first ink W 1  in replacing the first ink W 1  to the second ink W 2 , and to more surely replace ink. 
     In this embodiment, as in the first embodiment and the second embodiment, the work for attaching the first dummy sub-tank  107  to the sub-tank attaching unit  22 , attaching the first cartridge  101  to the cartridge attaching unit  21 , and temporarily releasing the connection between the valve unit main bodies  80  and the joint members  90  may be automatically performed under the command of the ink-supply control unit  61 . 
     Further, in this embodiment, as in the first embodiment and the second embodiment, the cartridge bag  102   b  and the like has flexibility, and hence the second ink W 2  may be filled by pressing the cartridge case  102   a  without using the suction pump  40   b.    
     Further, in this embodiment, as illustrated in  FIG. 17A  in the first embodiment and the second embodiment, for example, the two valve unit main bodies  80  may be attached to both sides of the sub-tank case  104   a  of the first sub-tank  104 , respectively. 
     Further, the sub-tank detecting means  63  and the cartridge detecting means  62  provided to the ink supplying system  111  in this embodiment may be removed. This is because, even if the sub-tank detecting means  63  and the cartridge detecting means  62  are not present, it is possible to detect the first sub-tank  104  and the first dummy sub-tank  107  attached to the sub-tank attaching unit  22  and to detect the first cartridge  101  attached to the cartridge attaching unit  21  by the operator. 
     First Modification 
     A first modification is described below. 
     For convenience of description, in the first modification, components same as those described in the embodiments of the present invention are denoted by the same reference symbols and description of the components is omitted. 
     An ink supplying system according to this modification is the same as the ink supplying system  111  according to the third embodiment illustrated in  FIGS. 18A to 18E . Moreover, the first sub-tank  104 , the second sub-tank  105 , the first cartridge  101 , the second cartridge  102 , the first dummy sub-tank  107 , and the second dummy sub-tank  108  illustrated in  FIGS. 18A  to E and a cleaning cartridge  103  illustrated in  FIG. 25  are used. 
     That is, the cleaning cartridge  103  includes a cartridge case  103   a  made of resin molded in a box shape, a cartridge bag  103   b  that is arranged in the inside of the cartridge case  103   a  and stores cleaning liquid C for cleaning ink, and a cartridge connecting section  103   c  serving as an inlet and an outlet of the cleaning liquid C to and from the cartridge bag  103   b.    
     With the ink supplying system according to this modification, ink ejected from the ink jet head  58  can be replaced, while being cleaned, from the first ink W 1  to the second ink W 2  by a method described below. 
     Next, an ink supplying method in the ink supply system according to the first modification is described.  FIG. 26  is a flowchart of the ink supplying method.  FIGS. 27 to 29  are explanatory diagrams illustrating respective steps of the ink supplying method. Further, a part of the explanatory diagrams illustrating the respective steps is the same as the explanatory diagram in the third embodiment of the present invention, and hence the explanatory diagram in the third embodiment is also referred to. 
     As illustrated in  FIG. 26 , in the ink supplying method by the ink supplying system according to the first modification, a cleaning main tank connecting step (Step S 27 ) and a cleaning step (Step S 28 ) are inserted between the first ink main tank storing step (Step S 22 ) and a first and second auxiliary connecting means replacing step (Step S 23 ) of the ink supplying method by the ink supplying system according to the third embodiment of the present invention illustrated in  FIG. 19 . 
     Following the first ink main tank storing step (Step S 22 ), in the cleaning main tank connecting step (Step S 27 ) performed in the state illustrated in  FIG. 21 , the operator of the ink jet printer releases the connection between the one end  53   a  of the first pipe  53  and the first cartridge  101  and connects the one end  53   a  of the first pipe  53  and the cleaning cartridge  103 . Then, the operator sends a signal representing the end of Step S 27  to the ink control device  61   a  via the input and output panel  47  and shifts to Step S 28  (see  FIG. 27 ). 
     Next, in the cleaning step (Step S 28 ), when the ink control device  61   a  detects that Step S 27  ends, the ink control device  61   a  drives the suction pump  40   b , fills the cleaning liquid C stored in the cleaning cartridge  103  into the first pipe  53 , the connection pipe  107   b  of the first dummy sub-tank  107 , the first divided pipe  55 , the second divided pipe  56 , and the ink jet head  58 , sucks out the first ink W 1 , cleans an ink path, stops the suction pump  40   b , and shifts to Step S 23  (see  FIG. 28 ). 
     In this way, the insides of the first pipe  53 , the first divided pipe  55 , the second divided pipe  56 , and the ink jet head  58  are cleaned by the cleaning liquid C. Therefore, when the second ink W 2  is filled later, the first ink W 1  and the second ink W 2  can be prevented from being mixed. 
     Next, when the first and second auxiliary connecting means replacing step (Step S 23 ) and the first and second main tanks replacing step (Step S 24 ) described in the third embodiment of the present invention are performed, the ink supplying system changes to a state illustrated in  FIG. 29 . 
     Steps after this are the same as the steps described in the third embodiment of the present invention. Therefore, description of the steps is omitted. 
     Second Modification 
     A second modification is described below. 
     For convenience of description, in the second modification, components same as those described in the embodiments of the present invention and the first modification are denoted by the same reference symbols and description of the components is omitted. 
     With the ink supplying system according to this modification, ink ejected from the ink jet head  58  can be replaced from the first ink W 1  to the second ink W 2  by a method described below. 
     An ink supplying system according to this modification is the same as the ink supplying system  111  according to the third embodiment illustrated in  FIGS. 18A to 18E . Moreover, the first sub-tank  104 , the second sub-tank  105 , the first cartridge  101 , the second cartridge  102 , and the second dummy sub-tank  108  illustrated in  FIGS. 18A to 18E  are used. 
     Next, an ink supplying method in the ink supply system according to the second modification is described.  FIG. 30  is a flowchart of the ink supplying method.  FIGS. 31 to 34  are explanatory diagrams illustrating respective steps of the ink supplying method. 
     In replacing the ink from the first ink W 1  to the second ink W 2 , as illustrated in  FIGS. 18A to 18E , each of the joint member  90  provided at the another end  53   b  of the first pipe  53  and the joint member  90  provided at the one end  55   a  of the first divided pipe  55  and the two valve unit main bodies  80  provided in the first sub-tank  104  are connected. Further, the first cartridge  101  is connected to the one end  53   a  of the first pipe  53 . The joint member  90  provided at the another end  55   b  of the first divided pipe  55  and the valve unit main body  80  provided at the one end  56   a  of the second divided pipe  56  are connected. Further, the first pipe  53 , the first divided pipe  55 , the second divided pipe  56 , and the ink jet head  58  are filled with the first ink W 1 . 
     When the ink control device  61   a  of the ink-supply control unit  61  receives a command from the CPU  46   a  of the main control unit  46  replace the ink, first, in a first ink auxiliary tank storing step (Step S 31 ), the ink control device  61   a  sets the supply pump  60  in an opened state. 
     Next, the operator of the ink jet printer temporarily releases the connection between the joint member  90  provided at the another end  55   b  of the first divided pipe  55  and the valve unit main body  80  provided at the one end  56   a  of the first divided pipe  56 , leads the air into the first divided pipe  55  from the joint member  90 , and shifts to Step S 32  (see  FIG. 31 ). 
     Then, at least a part of the first ink W 1  in the first divided pipe  55  is stored in the sub-tank bag  104   b  of the first sub-tank  104 . Therefore, an amount of ink to be discarded during ink replacement can be controlled. 
     Next, in a second auxiliary connecting means connecting step (Step S 32 ), the operator releases the connection between each of the joint member  90  provided at the another end  53   b  of the first pipe  53  and the joint member  90  provided at the one end  55   a  of the first divided pipe  55  and the two valve unit main bodies  80  provided to the first sub-tank  104 . Then, the operator connects the two joint members  90  and the two valve unit main bodies  80  provided to the second dummy sub-tank  108 . 
     Moreover, in a first and second main tanks replacing step (Step S 33 ), the operator releases the connection between the one end  53   a  of the first pipe  53  and the first cartridge  101 , and connects the one end  53   a  of the first pipe  53  and the second cartridge  102  (see  FIG. 22 ). The operator sends a signal representing the end of Step S 33  to the ink control device  61   a  via the input and output panel  47  and shifts to Step S 34  (See  FIG. 32 ). 
     Next, in a second ink filling step (Step S 34 ), when the ink control device  61   a  detects that Step S 33  ends, the ink control device  61   a  drives the suction pump  40   b , fills the second ink W 2  stored in the second cartridge  102  into the first pipe  53 , the connection pipe  108   b  of the second dummy sub-tank  108 , the first divided pipe  55 , the second divided pipe  56 , and the ink jet head  58 , stops the suction pump  40   b  when the filling is completed, and shifts to Step S 35  (see  FIG. 33 ). 
     Finally, in a second auxiliary tank connecting step (Step S 35 ), the operator releases the connection between each of the joint member  90  provided at the another end  53   b  of the first pipe  53  and the joint member  90  provided at the one end  55   a  of the first divided pipe  55  and the two valve unit main bodies  80  provided to the second dummy sub-tank  108 . Then, the operator connects the two joint members  90  and the two valve unit main bodies  80  provided to the second sub-tank  105  (see  FIG. 34 ). 
     In this way, with the ink jet printer according to the second modification, the air is prevented from flowing into the ink when the ink is shifted. Therefore, the removing of the bubbles contained in the ink, which was conventionally performed by the on-off valve provided to the tube provided in the auxiliary tank is unnecessary. Therefore, ink replacement can be easily performed. 
     Third Modification 
     A third modification is described below. 
     For convenience of description, in the third modification, components same as those described in the embodiments of the present invention and other modifications are denoted by the same reference symbols and description of the components is omitted. 
     An ink supplying system according to this modification is the same as the ink supplying system  111  according to the third embodiment illustrated in  FIGS. 18A to 18E . Moreover, the first sub-tank  104 , the second sub-tank  105 , the first cartridge  101 , the second cartridge  102 , and the second dummy sub-tank  108  illustrated in  FIGS. 18A to 18E  and a cleaning cartridge  103  illustrated in  FIG. 25  are used. 
     With the ink supplying system according to this modification, ink ejected from the ink jet head  58  can be replaced, while being cleaned, from the first ink W 1  to the second ink W 2  by a method described below. 
     Next, an ink supplying method in the ink supply system according to the third modification is described.  FIG. 35  is a flowchart of the ink supplying method.  FIGS. 36 to 37  are explanatory diagrams illustrating respective steps of the ink supplying method. Further, a part of the explanatory diagrams illustrating the respective steps is the same as the explanatory diagram in the second embodiment of the present invention, and hence the explanatory diagram in the second embodiment is also referred to. 
     As illustrated in  FIG. 35 , in the ink supplying method by the ink supplying system according to the third modification, a cleaning main tank connecting step (Step S 32 ) and a cleaning step (Step S 33 ) are inserted between the second auxiliary connecting means connecting step (Step S 32 ) and a first and second main tanks replacing step (Step S 33 ) of the ink supplying method by the ink supplying system according to the second modification illustrated in  FIG. 30 . 
     In the state illustrated in  FIG. 31 , the second auxiliary connecting means connecting step (Step S 32 ) described in the second modification is performed and, subsequently, the cleaning main tank connecting step (Step S 36 ) is performed. In the cleaning main tank connecting step, the operator of the ink jet printer releases the connection between the one end  53   a  of the first pipe  53  and the first cartridge  101  and connects the one end  53   a  of the first pipe  53  and the cleaning cartridge  103 . Then, the operator sends a signal representing the end of Step S 36  to the ink control device  61   a  via the input and output panel  47  and shifts to Step S 37  (see  FIG. 36 ). 
     Next, in the cleaning step (Step S 37 ), when the ink control device  61   a  detects that Step S 36  ends, the ink control device  61   a  drives the suction pump  40   b , fills the cleaning liquid C stored in the cleaning cartridge  103  into the first pipe  53 , the connection pipe  108   b  of the first dummy sub-tank  108 , the first divided pipe  55 , the second divided pipe  56 , and the ink jet head  58 , stops the suction pump  40   b , and shifts to Step S 33  (see  FIG. 37 ). 
     In this way, the insides of the first pipe  53 , the first divided pipe  55 , the second divided pipe  56 , and the ink jet head  58  are cleaned by the cleaning liquid C. Therefore, when the second ink W 2  is filled later, the first ink W 1  and the second ink W 2  can be prevented from being mixed. 
     Steps after this are the same as the first and second main tanks replacing step (Step S 33 ) described in the second modification and subsequent steps. Therefore, description of the steps is omitted.