Abstract:
A liquid ejecting apparatus comprising a liquid ejection head that ejects a liquid via nozzles; a first passage that communicates with the liquid ejection head, the first passage being configured to supply the liquid to the liquid ejection head; a second passage that communicates with the first passage in the liquid ejection head, the second passage forming, in cooperation with the first passage, a circulation passage; and a liquid driving unit provided in the circulation passage, the liquid driving unit being configured to move the liquid in the circulation passage when driven. The liquid is moved, by the driven liquid driving unit, at a first flow rate that maintains a meniscus of the liquid inside the nozzles after the liquid is moved at a second flow rate that is faster than the first flow rate.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of, and claims priority under 35 U.S.C. §120 on, U.S. application Ser. No. 14/580,051, filed Dec. 22, 2014, which is a continuation of U.S. application Ser. No. 14/070,933, filed Nov. 4, 2013, now U.S. Pat. No. 9,033,466, which is a division of U.S. application Ser. No. 13/025,727, filed Feb. 11, 2011, now U.S. Pat. No. 8,602,520, which claims priority under 35 U.S.C. §119 on Japanese patent application nos. 2010-030432 and 2010-233746, filed Feb. 15, 2010 and Oct. 18, 2010 respectively. The content of each such related application is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a liquid ejecting apparatus and a maintenance method of the liquid ejecting apparatus. 
     2. Related Art 
     An ink jet printer (hereinafter referred to as a “printer”) capable of ejecting ink (liquid) droplets onto a printing medium from ejection orifices (nozzles) of a printing head (liquid ejection head) is known as a liquid ejecting apparatus. 
     Such a printer includes a tank for containing ink therein, and supplies the ink inside the tank to the printing head and ejects the ink from the printing head. The ink is generally made of a dispersion liquid containing solid content, such as pigment or the like, and a dispersion medium such as solvent. 
     In a case where the printer uses the ink, in particular, if the printer is powered-off and is maintained in a disused state, the solid content contained in the ink contained in the tank is separated and settled (sunken), so that the concentration of the solid content in the ink becomes uneven. If the solid content is settled and thus the concentration of the solid content becomes uneven, when the ink is ejected by again turning the power on after the power is turned off when the printing is carried out, the solid content settled in the tank is supplied to an ink jet head side as it is, such that the nozzles of the printing head are clogged or unevenness defects are produced in the printing quality. 
     In order to prevent such a problem, there is known a printing apparatus (printer) including two supply passages which are provided to communicate with the tank for storing (containing) the ink with the printing head, to circulate the ink between the printing head and the tank (for example, refer to JP-A-2007-331281). 
     However, there is a concern that the circulation of the ink may cause inflow of gas from an ejection head in the above-described configuration. 
     SUMMARY 
     An advantage of some aspects of the invention is that it provides a liquid ejecting apparatus which can suppress inflow of gas from an ejection head at a maintenance operation. 
     According to an aspect of the invention, there is provided a liquid ejecting apparatus comprising a liquid ejection head that ejects a liquid via nozzles; a first passage that communicates with the liquid ejection head, the first passage being configured to supply the liquid to the liquid ejection head; a second passage that communicates with the first passage in the liquid ejection head, the second passage forming, in cooperation with the first passage, a circulation passage; and a liquid driving unit provided in the circulation passage, the liquid driving unit being configured to move the liquid in the circulation passage when driven. The liquid is moved, by the driven liquid driving unit, at a first flow rate that maintains a meniscus of the liquid inside the nozzles after the liquid is moved at a second flow rate that is faster than the first flow rate. 
     The liquid ejecting apparatus may further include the feature that movement of the liquid at the second flow rate is capable of breaking the meniscus of the liquid inside the nozzles. 
     Preferably, the liquid ejecting apparatus further comprises a cap configured to cover an area that includes the nozzles of the liquid ejection head, where the liquid is moved at the second flow rate in a state in which the liquid ejection head is covered by the cap. 
     Preferably, the liquid ejecting apparatus further comprises a flexible member that constitutes part of an inner wall of the circulation passage, the flexible member deforming in accordance with a change of liquid pressure in the circulation passage. 
     The liquid ejecting apparatus preferably further comprises a valve provided in the first passage to allow and restrict flow of the liquid, which, in embodiments including the flexible member, may be in accordance with deformation of the flexible member. 
     The liquid ejecting apparatus may further include the feature of the valve allowing the flow of the liquid in the first passage to the liquid ejection head when pressure in the first passage between the valve and the liquid ejection head decreases and reaches a predetermined pressure higher than a first pressure at which the liquid is moved at the first flow rate. 
     Other objectives and attainments will become apparent from the following description taken in conjunction with drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIG. 1  is a perspective view schematically illustrating the configuration of a printer apparatus according to an embodiment of the invention. 
         FIG. 2  is a plan view of main parts in the vicinity of an ejection head. 
         FIG. 3  is a plan view illustrating a nozzle orifice forming surface of an ejection head. 
         FIG. 4  is a view illustrating the cross-sectional configuration of an ejection head. 
         FIG. 5  is a diagram illustrating the schematic configuration of a maintenance mechanism. 
         FIG. 6  is a block diagram illustrating the configuration of a printer apparatus. 
         FIG. 7  is a view illustrating the operation of a printer apparatus. 
         FIG. 8  is a view illustrating the operation of a printer apparatus. 
         FIG. 9  is a view illustrating the operation of a printer apparatus. 
         FIGS. 10A and 10B  are perspective views schematically illustrating the configuration of a printer apparatus according to another embodiment of the invention. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     A liquid ejecting apparatus according to an embodiment of the invention will now be described with reference to the accompanying drawings. In this instance, in the various drawings used in the following description, the scales of the various constituents of the liquid ejecting apparatus are appropriately modified in order to allow the respective constituents to have recognizable sizes. In this embodiment, an ink jet printer is exemplified as the liquid ejecting apparatus. 
       FIG. 1  is a perspective view schematically illustrating the configuration of the ink jet printer (hereinafter, simply referred to as a printer apparatus PRT) according to an embodiment of the invention.  FIG. 2  is a plan view of main parts in the vicinity of an ejection head.  FIG. 3  is a plan view illustrating a nozzle orifice forming surface of the ejection head. 
     In  FIG. 1 , there is a case where a Cartesian coordinate system is set, and then a positional relationship of each component is described with reference to the Cartesian coordinate system. In such a case, a transport direction of a printing medium M is set to an X direction (horizontal direction in  FIG. 1 ), a direction perpendicular to a nozzle forming region  15  of an ejection head  11  is set to a Z direction (vertical direction in  FIG. 1 ), and a direction perpendicular to an X-Z plane formed by an X-axis and a Y-axis is set to a Y direction (depth direction of paper in  FIG. 1 ). 
     As shown in these drawings, the printer apparatus PRT is an apparatus capable of printing images, characters or the like on a printing medium M. Paper, plastic or the like can be used as the printing medium M. The printing apparatus PRT includes an ink ejection mechanism IJ, a transport mechanism CR, a maintenance mechanism MN, and a control device CONT. 
     The ink ejection mechanism IJ is a unit capable of ejecting ink droplets (liquid) on the printing medium M. The ink ejection mechanism IJ includes an ejection head (liquid ejection head)  11  and an ink supply unit  12 . The ink used in this embodiment contains dye or pigment, and solvent for dissolving or dispersing it, as basic components, and uses a liquid material added with various additives, if necessary. 
     The ejection head  11  is a head capable of ejecting ink droplets of plural colors on the printing medium M. The ejection head  11  is an ejection head of a line type having a nozzle forming region  15  along the length (maximum printing sheet width W) exceeding at least one side of the printing medium M of the maximum size which is a target of the printer apparatus PRT, as shown in  FIG. 2 . The ejection head  11  is provided in such a manner that it is able to move in the Z direction. The ejection head  11  has nozzles  13  and common ink chambers  14  shown in  FIG. 4 . 
     The common ink chamber  14  is one chamber (common ink chambers  14 Y,  14 M,  14 C, and  14 K) for retaining each ink corresponding to, for example, four colors (yellow: Y, magenta: M, cyan: C, and black: K). The nozzle forming regions  15  is provided at a portion corresponding to the common ink chamber  14  of each color (nozzle forming regions  15 Y,  15 M,  15 C and  15 K). 
     The nozzles  13  are orifice portions which are discretely installed in the nozzle forming regions  15 Y,  15 M,  15 C, and  15 K respectively of the injection head  11  to discharge the ink droplets of four colors. The plurality of nozzles  13  respectively communicate with one common ink chamber  14 . The nozzles  13  are discretely arranged in the Y direction (nozzle row L), as shown in  FIG. 3 . One row or plural rows of the nozzle row L are provided in parallel with respect to the nozzle forming regions  15 Y,  15 M,  15 C, and  15 K of each color. The number of the nozzles  13  or the number of the nozzle rows L is appropriately set. The surface of the injection head  11 , in which the nozzles  13  are installed, becomes an injection surface  11 A. The injection surface  11 A is provided at the −Z side of the injection head  11 . The injection head  11  is adapted to inject the ink droplets in the −Z side. 
       FIG. 4  is a cross-sectional view illustrating the configuration of the injection head  11 . 
     As shown in  FIG. 4 , the injection head  11  includes a head body  18 , and a liquid passage forming unit  22  which is connected to the head body  18 . The liquid passage forming unit  22  has a vibration plate  19 , a liquid passage substrate  20 , and a nozzle substrate  21 . 
     The head body  18  is provided with a plurality of piezoelectric elements  25 , and each of the piezoelectric elements  25  is provided corresponding to each of the plurality of nozzles  13 . 
     The liquid passage forming unit  22  has the common ink chambers  14 , an ink supply orifice  30  connected to the corresponding common ink chamber  14 , and a pressurized chamber  31  connected to the ink supply orifice  30 . The pressurized chamber  31  is provided corresponding to each nozzle  13 . Each of the pressurized chambers  31  is connected to the nozzle  13  at an end opposite to the common ink chamber  14 . 
     The nozzle substrate  21  has a plurality of nozzles  13  formed at a predetermined interval (pitch) in a predetermined direction. An outer surface of the nozzle substrate  21  is an injection surface  11 A. 
     According to the injection head  11  having the above-described configuration, when a driving signal is input to the piezoelectric element  25 , the piezoelectric element  25  expands or contracts. The expansion or contraction of the piezoelectric element  25  is transmitted as deformation of the vibration plate  19 . Due to the deformation of the vibration plate  19 , the volume of the pressurized chamber  31  is changed, and thus the pressure of the pressurized chamber  31  receiving the ink therein is varied. The variation in pressure causes the ink to eject from the nozzles  13 . 
     The transport mechanism CR includes a sheet transfer roller  35 , a discharge roller  36 , and the like. The sheet transfer roller  35  and the discharge roller  36  are adapted to be rotated by a motor mechanism (not illustrated). The transport mechanism CR transports the printing medium M along a transport path MR in connection with ejection operation of the ink droplets by the ink ejection mechanism IJ. 
     Returning to  FIG. 1 , the ink supply section (liquid storage unit)  12  is placed at one side of the ink ejection mechanism IJ, and is connected to each of the common ink chambers  14 Y,  14 M,  14 C, and  14 K of the ejection head  11 . The ink supply unit  12  has ink tanks  12 Y,  12 M,  12 C, and  12 K for storing the ink of four colors. 
     The ink supply unit  12  is connected to the ejection head  11  via a first supply tube SR 1  and a second supply tube SR 2 . The first supply tube SR 1  is a passage (first supply passage) for supplying the ink from the ink supply unit  12  to the ejection head  11 . The first supply tube SR 1  is provided with a valve unit VU. The second supply tube SR 2  is a passage (second supply passage) communicating with the ink supply unit  12  and the ejection head  11 . The second supply tube SR 2  is provided with a supply pump (liquid driving unit) RP. A flow of the ink supplied from the ink supply unit  12  to the ejection head  11  and a flow of the ink supplied from the ejection head  11  to the ink supply unit  12  are produced in accordance with a driving direction of the supply pump RP. 
       FIG. 5  is a cross-sectional view schematically illustrating the configuration of the valve unit VU. 
     An ink receiving chamber RM is formed in a receiving chamber forming member  50 . The receiving chamber forming member  50  has a partition portion  51  at a center portion of the horizontal direction in the drawing. The ink receiving chamber RM is divided into a first chamber (recessed portion) R 1  and a second chamber R 2  by the partition portion  51 . The partition portion  51  is formed with a communication portion  52 . The first chamber R 1  of the ink receiving chamber RM is connected to the ink supply unit  12  via the first supply tube SR 1 . The second chamber R 2  is connected to the ejection head  11  via the first supply tube SR 1 . The first chamber R 1  and the second chamber R 2  communicate with each other via the communication portion  52 . In this way, the path from the ink supply unit  12  to the ejection head  11  is communicated in the order of the ink supply unit  12 , the first supply tube SR 1  (ink supply unit  12  side), the first chamber R 1 , the communication portion  52 , the second chamber R 2 , the first supply tube SR 1  (injection head  11  side) and the ejection head  11 . 
     A portion (a left end in the drawing), which is different from the partition portion  51 , of the wall portion enclosing the first chamber R 1  of the receiving chamber forming member  50  is formed with an opening. The opening is formed so as to communicate with the exterior of the first chamber R 1  and the ink receiving chamber RM. A flexible member F is attached to the opening, and the opening is constantly closed by the flexible member F. 
     The valve VB is formed to extend the first chamber R 1  and the second chamber R 2 . The valve VB has a plate-shaped portion V 1 , a flange portion V 2 , and a shaft portion V 3 . The plate-shaped portion V 1  is adhered to the flexible member F. The flange portion V 2  is provided in the second chamber R 2 , and the flange portion V 2  is provided in the second chamber R 2 . The flange portion V 2  is formed with a sealing portion V 4  for closing the communication portion  52 . The communication portion  52  is interrupted by bringing the sealing portion V 4  into contact with the partition portion  51 . 
     The shaft portion V 3  is placed to penetrate through the communication portion  52 . The plate-shaped portion V 1  and the flange portion V 2  are connected to each other by the shaft portion V 3 . The valve VB is configured in such a way that, as the flexible member F is bent in the direction to decrease the internal volume of the ink receiving chamber RM, the sealing portion V 4  is spaced apart from the partition portion  51  to open the communication portion  52 . 
     A biasing mechanism SP is interposed between the plate-shaped portion V 1  and the partition portion  51 . A spring member or the like is preferably used as the biasing mechanism SP. The biasing mechanism SP bends the flexible member F in a direction of increasing an internal volume of the first chamber R 1 , thereby biasing the plate-shaped portion V 1  toward a left side (direction spaced apart from the partition portion  51 ) of the drawing. The biasing force of the biasing mechanism SP is set in such a way that when the ink receiving chamber RM is lower than the predetermined pressure, the sealing portion V 4  opens the communication portion  52 , and for the rest, the sealing portion V 4  interrupts the communication portion  52 . 
     In the case where the ink is ejected from the ejection head  11 , since the communication portion  52  is interrupted by the sealing portion V 4 , negative pressure is generated in the liquid passage from the first chamber R 1  to the ejection head  11 . If the force of bending the flexible member F due to the negative pressure is stronger than the biasing force of the biasing mechanism SP, the flexible member F is bent and thus the communication portion  52  is opened. 
     Since the first chamber R 1  communicates with the ejection head  11  and the second chamber R 2  communicates with the ink supply unit  12 , the ink is supplied from the second chamber R 2  to the first chamber R 1  side via the communication portion  52 . If the negative pressure from the first chamber R 1  to the ejection head  11  by the supply of the ink is decreased, the biasing force of the biasing mechanism SP is higher than the corresponding negative pressure, the communication portion  52  is interrupted by the sealing portion V 4 . 
     In this way, since the negative pressure is generated in the passage from the first chamber R 1  to the ejection head  11 , the valve unit VU has an action of adjusting an ink meniscus of the nozzles, and an action of a check valve (one-way valve) through which the ink flows only in the direction from the second chamber R 2  to the first chamber R 1 . 
     Returning to  FIG. 1 , the supply pump RP adjusts a flow direction and flow velocity (supply speed) of the ink flowing in the second supply tube SR 2 . According to the flow direction of the ink, the ink can be switched and supplied in either of a forward direction from the ejection head  11  to the ink supply unit  12  or a backward direction from the ink supply unit  12  to the ejection head  11 . In this instance, when the flow of the ink in the second supply tube SR 2  is the forward direction, the flow of the ink in the first supply tube SR 1  is set to a flow direction from the ink supply unit  12  to the ejection head  11 . In addition, when the flow velocity is adjusted, the supply pump RP is adapted to vary the flow velocity of at least ink supplied in the forward direction, depending upon whether or not the ejection surface  11 A is covered by a cap member  42  which will be described below. In this instance, the variation in flow velocity is controlled by the control device CONT. 
     The maintenance mechanism MN performs a maintenance for the ejection head  11 . The maintenance mechanism MN includes the cap member  42  and an actuation mechanism ACT. The cap member  42  is formed in the shape of a plate by using a material, for example, rubber, elastomer or the like. The cap member  42  has a close contact surface  42   a  which is brought into close contact with the ejection surface  11 A of the ejection head  11 . The close contact surface  42   a  is provided to be opposite to the ejection surface  11 A of the ejection head  11 . The cap member  42  is formed to have a dimension large enough to be able to cover at least a range, in which the nozzle NZ is formed, of the ejection surface  11 A. For this reason, the cap member  42  is formed so as to bring it into close contact with and over the surface, in which the nozzle NZ is formed, of the ejection surface  11 A, so that the surface is covered. 
     In this embodiment, an absorbing member (not illustrated) for receiving the ink ejected from each nozzle  13  of the ejection head  11  is provided separately from the cap member  42 . The absorbing member is able to be placed on a flying path in a state where the cap member  42  is retracted from the flying path of the ink ejected from each nozzle  13 . In this instance, the absorbing member placed on the flying path of the ink receives the ink from the head. 
     The actuation mechanism ACT moves the cap member  42  between the ejection head  11  and the actuation mechanism. An actuator such as cam mechanism, a motor mechanism, air cylinder mechanism or the like may be used as the actuation mechanism ACT. Of course, other actuator can be used. 
       FIG. 6  is a block diagram illustrating the electrical configuration of the printer apparatus PRT. 
     The printer apparatus PRT according to the embodiment includes the control device CONT for controlling the whole operation. The control device CONT is connected to an input device  59  for inputting various information about the operation of the printer apparatus PRT, and a memory device for storing various information about the operation of the printer apparatus PRT. 
     The control device CONT is connected to each section of the printer apparatus PRT, such as the ink ejection mechanism IJ, the transport mechanism CR, the maintenance mechanism MN, or the like. The printer apparatus PRT includes a driving signal generator  62  for generating a driving signal which is input to the driving unit having the piezoelectric element  25 . The driving signal generator  62  is connected to the control device CONT. 
     The driving signal generator  62  is input with data indicative of a variation in voltage value of a discharge pulse which is input to the piezoelectric element  25  of the ejection head  11 , and a timing signal defining a timing changing a voltage of the discharge pulse. The driving signal generator  62  generates a driving signal, such as discharge pulse, based on the input data and the timing signal. 
     Next, the operation of the printer apparatus PRT including the above-described configuration will be described. 
     In a case where the ejection head  11  carries out the printing operation, the control device CONT places the printing medium M on a support surface (not illustrated) by using the transport mechanism CR. After the printing medium M is placed, the control device CONT inputs the driving signal to the piezoelectric element  25  from the driving signal generator  62  based on the image data of an image to be printed. 
     If the driving signal is input to the piezoelectric element  25 , the piezoelectric element  25  is expanded or contracted to eject the ink from the nozzles  13 . The desired image is formed on the printing medium M by the ink ejected from the nozzles  13 . 
     A capping operation is carried out as the maintenance operation of the ejection head  11 . In the case of carrying out the capping operation, the control device CONT presses the cap member  42  towards the ejection head  11  side by using the driving mechanism ACT. The gap between the cap member  42  and the ejection head  11  is sealed by the operation. 
     If the power source of the printer apparatus PRT is turned off and thus is maintained in a disused state, a solid content contained in the ink which is received in the ink supply unit  12  is separated and settled (sunken), so that the concentration of the solid content in the ink becomes uneven. If the solid content is settled and thus the concentration of the solid content becomes uneven, when the ink is ejected to carry out the printing by again turning the power on after the power is turned off, the settled solid content is supplied to the ejection head  11  side as it is. As a result, there is problem in that the nozzles of the ejection head  11  may be clogged or unevenness may occur in the printing quality. 
     Accordingly, in order to prevent such a problem, the ink should be circulated between the ink supply unit  12  and the ejection head  11 . The control device CONT operates the supply pump RP to cause the ink in the second supply tube SR 2  to flow in the forward direction (direction from the ejection head  11  to the ink supply unit  12 ) or the backward direction (direction from the ink supply unit  12  to the ejection head  11 ). 
     As a specific example, the control device CONT operates the supply pump RP to cause the ink to flow in the forward direction in the state where the ejection surface  11 A of the ejection head  11  is covered by the cap member  42 , as shown in  FIG. 7 . The negative pressure is generated in the first chamber R 1  by the operation, and thus the sealing portion V 4  of the valve VB opens the communication portion  52 , and the valve unit VU comes to be is in the opened state, so that the passage is communicated from the ink supply unit  12  to the ejection head  11 . For this reason, the ink is supplied from the ink supply unit  12  to the ejection head  11  via the first supply tube SR 1 . At this time, although the negative pressure is generated in the ejection head  11  which is positioned at the upstream side of the supply pump RP, since the ejection surface  11 A is covered by the cap member  42 , the air does not flow in the nozzles  13 , so that the ink does not leak from the nozzles  13 . For this reason, it is easy to stir the settled solid content components by increasing the flow velocity (supply speed) of the ink. Since the operation is carried out in the state in which the power source of the printer device PRT is turned on, it is possible to shorten the time needed to supply the ink in a short time. 
     In addition, as another aspect, the control device CONT may operate the supply pump RP so that the ink flows in the forward direction, as shown in  FIG. 8 , in the state where the ejection surface  11 A of the ejection head  11  is not covered by the cap member  42 . In this instance, since the ink does not flow in from the nozzles  13 , the control device CONT operates the supply pump RP so that the pressure P I  of the ink becomes a pressure maintaining the meniscus of the ink in the corresponding nozzle  13 . 
     In a case where the pressure P O  in the first supply tube SR 1  which is required to allow the ink to pass the valve unit VU from the ink supply unit  12  is −100 Pa, and the pressure P M  of maintaining the meniscus in the nozzle  13  is −200 Pa, the supply speed of the ink by the supply pump RP is adjusted in a liquid driving process so that the pressure P I  of the ink is set to a value (for example, −150 Pa or the like) therebetween. In this instance, if a case where the flow pressure P I  of the ink is higher than the pressure P O , since the valve unit VU is in the closed state, the ink does not flow. In addition, in a case where the pressure P M  of maintaining the meniscus in the nozzle  13  is less than −200 Pa, the flow pressure P I  of the ink does not maintain the meniscus of the ink in the nozzle  13 , such that the discharge amount of the ink cannot be accurately controlled. Accordingly, it is preferable that P M &lt;P I &lt;P O . The above-mentioned values are merely one example, and the invention is not limited thereto. 
     The operation of supplying the ink according to the embodiment shown in  FIG. 8  can be carried out for the period in which the power source of the printer apparatus PRT is turned on, and is carried out for the period different from the period in which the ink is ejected onto the printing medium M by the ejection head  11 . In addition, it is preferable that after the settlement of the ink is solved by performing the operation of supplying the ink according to the embodiment shown in  FIG. 7 , the operation of supplying the ink according to the embodiment shown in  FIG. 8  is carried out at the flow velocity not settling the ink. 
     In addition, as another aspect, the control device CONT may drive the supply pump RP so that the ink flows in the backward direction, as shown in  FIG. 9 , in the state where the ejection surface  11 A of the ejection head  11  is not covered by the cap member  42 . In this instance, since the first chamber R 1  is pressurized and the flexible member F is bent in the direction of increasing the volume of the first chamber R 1 , the communication portion  52  is interrupted by the sealing portion V 4 . For this reason, in the state where the valve unit VU is in the closed state, the flow of the ink does not occur in the first supply tube SR 1 . 
     Further, the ink flowing into the ejection head  11  via the second supply tube SR 2  is discharged outwardly to the ejection head  11  from the nozzle  13 . Here, since the cap member  42  is retracted from the ejection path of the ejection head  11 , the discharged ink is received by the absorbing member (not illustrated) or the like. The flushing (cleaning) operation can be performed by the ink supplied from the second supply tube SR 2  side. 
     When the printing is carried out by using the ejection head  11 , there is a case where alien substances are adhered to the nozzles  13  or the ink with increased viscosity is adhered to the nozzles  13 . In this instance, at least one of the nozzles  13  provided in the ejection head  11  is clogged, thereby leading to a defective ejection state. The operation of supplying the sink, as shown in  FIG. 9 , can be performed for the purpose of addressing the above-described defective ejection state of the nozzles  13 . Since the nozzles  13  with the defective ejection state can be cleaned through the ink supply operation, a suction mechanism for the cap member  42  is not necessary. Of course, the operation of supplying the ink may be performed for other purposes or in other cases. 
     As described above, according to this embodiment, since the printer apparatus includes the first supply tube SR 1  for supplying the ink from the ink supply unit  12  to the ejection head  11 , and the second supply tube SR 2  which is provided separately from the first supply tube SR 1 , and communicates with the ejection head  11  and the ink supply unit  12 , in which the ink is supplied in the forward direction by the supply pump RP provided in the second supply tube SR 2  in the state where the cap member  42  comes into close contact with the ejection head  11 , the ink is supplied in the state where the nozzles  13  are sealed. For this reason, it is possible to prevent inflow of the air from the nozzles at an interval of the ink supply. In addition, it is possible to prevent the ink from leaking from the nozzles. 
     It should be noted that the technical scope of the invention is not limited to the above-described embodiment, and proper modifications can be undergone within the scope without deviating from the aspects of the invention. 
     For example, in the above-described embodiment, a configuration is described in which the invention is applied to the printer employing the line type head. However, the invention is not limited thereto, and may be applied to the printer apparatus PRT 2  employing a serial type head, as shown in  FIG. 10A . 
     In this instance, the configuration of the printer apparatus PRT 2  will be described in brief. The printer apparatus PRT 2  includes a printer body  105 , and a carriage  104  on which a sub tank  102  and an ejection head  103  are mounted. The printer body  105  is provided with a carriage moving mechanism  154  for reciprocating the carriage  104 , a capping device  150  for use in the cleaning operation or the like which suctions the ink with increased viscosity from each nozzle of the ejection head  103 , and an ink cartridge  106  for storing the ink which is supplied to the ejection head  103  via an ink supply tube  134 . The printer body  105  is provided with a sheet transport mechanism (not illustrated) for transporting a printing sheet. The sheet transport mechanism includes a sheet transport motor (not illustrated) or a sheet transport roller (not illustrated) which is rotated by the sheet transport motor, and is adapted to sequentially feed the printing sheets onto a platen  113  in connection with recording (printing) operation. 
     The carriage moving mechanism  154  includes a guide shaft  108  installed in a width direction of the printer body  105 , a motor  109 , a driving pulley  110  which is connected to a rotation shaft of the motor  109  and is rotated by the motor  109 , an idle pulley  111  installed opposite to the driving pulley  110  in the width direction of the printer body  105 , and a timing belt  112  suspended between the driving pulley  110  and the idle pulley  111  and is connected to the carriage  104 . The carriage moving mechanism  154  drives the motor  109 , so that the carriage  104  reciprocates along the guide shaft  108  in a main scanning direction. 
     The capping device  150  is placed at a home position in the printer body  105 . The home position is an end area more outside than a printing region in the moving region of the carriage  104 , and is set to a place in which the carriage  104  is positioned in a case where a power source is turned off or the recording is not performed for a long time. The printer apparatus PRT 2  includes the configuration as described above. 
     In addition, although the configuration in which the ejection head  11  is directly connected to the ink supply unit  12  is exemplified in this embodiment, the invention is not limited thereto. As shown in  FIGS. 10A and 10B , a configuration may be provided, in which the ink cartridge (main tank)  106  and the sub tank  102  are provided as a tank for storing the ink, and the ink is circulated between the sub tank  102  and the ejection head  103  respective. In this instance, the invention can be applied by installing the first supply tube SR 1  and the second supply tube SR 2  as a flow passage for circulating the ink, placing the valve unit VU in the first supply tube SR 1 , and placing the supply pump RP in the second supply tube SR 2 . 
     In the above description, the ink jet printer and ink cartridge are employed, but a liquid ejecting apparatus for ejecting or discharging a liquid other than ink, and a liquid container for receiving the liquid may be employed. It may be applied to various liquid ejecting apparatuses including a liquid ejection head for discharging a minute number of liquid droplets. In this instance, the expression “liquid droplets” means the liquid ejected from the liquid ejecting apparatus, and includes a liquid having a particle shape, a tear shape, or a linear shape. Further, here, the liquid may be a material which can be ejected from the liquid ejecting apparatus. 
     For example, a liquid-state material may be used, and includes a liquid-state material such as sol or gel water having a high or low viscosity, a liquid-state material such as an inorganic solvent, an organic solvent, a liquid, a liquid-state resin, or liquid-state metal (metallic melt), and a material in which particles of a functional material having a solid material such as pigment or metal particles is dissolved, dispersed, or mixed with solvent in addition to a liquid, as one state of a substance. In addition, ink described in the embodiments may be exemplified as a typical example of the liquid, liquid crystal and the like. Here, the ink indicates general water-based ink, oil-based ink, gel ink, or hot-melt ink which contains various liquid compositions. 
     As a detailed example of the liquid ejecting apparatus, for example, a liquid crystal display, an EL (electro-luminance) display, a plane-emission display, a liquid ejecting apparatus for ejecting a liquid containing dispersed or melted materials such as an electrode material or a color material used to manufacture a color filter, a liquid ejecting apparatus for ejecting a biological organic material used to manufacture a biochip, a liquid ejecting apparatus for ejecting a liquid as a sample used as a precision pipette, a printing apparatus, or a micro dispenser may be used. 
     In addition, a liquid ejecting apparatus for ejecting lubricant from a pinpoint to a precision machine such as a watch or a camera, a liquid ejecting apparatus for ejecting a transparent resin liquid such as a UV-curing resin onto a substrate in order to form a minute hemispherical lens used for an optical transmission element or the like, or a liquid ejecting apparatus for ejecting an etching liquid such as an acid liquid or an alkali liquid in order to perform etching on a substrate or the like may be adopted. The invention may be applied to at least one kind of the above-described ejection apparatuses and the liquid container.