Abstract:
A liquid ejection apparatus includes a liquid ejection head having a plurality of nozzle units, a plurality of capping devices, a movement mechanism, a plurality of suctioning tubes, a suctioning mechanism, a connection device, and a control device. The control device controls the suctioning mechanism to suction fluid in the capping device corresponding to one of the nozzle units and the capping device corresponding to a different one of the nozzle units. In response to expiration of a predetermined time period, which is a predetermined amount of time that the suctioning mechanism generates a suctioning force, the control device controls to disconnect the capping device corresponding to the one of the nozzle units from the suctioning mechanism.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from Japanese Patent Applications Nos. 2012-288991 and 2012-288993 filed on Dec. 28, 2012, which are incorporated herein by reference. 
     FIELD OF DISCLOSURE 
     The disclosure relates generally to a liquid ejection apparatus configured to eject liquid from nozzles, a method of maintaining the liquid ejection apparatus, and a non-transitory, computer-readable medium for controlling the liquid ejection apparatus. 
     BACKGROUND 
     An inkjet printer includes inkjet heads, each having a nozzle surface. The nozzle surfaces of the inkjet heads are covered or sealed with corresponding head caps. One suctioning pump is sequentially connected to the head caps to suction ink from nozzles of the inkjet heads. Viscous ink in internal passages of the inkjet heads, including the nozzles, is discharged into the head caps. Thus, ink ejection performance of the inkjet heads is improved. 
     SUMMARY 
     In the inkjet printer, if ink discharged into the head cap is dried, the dried ink may close or clog a passage from the head cap to the suctioning pump. Therefore, after ink is discharged into the head cap, it is desirable to continue the suctioning of ink with the suctioning pump, with the head cap open, to discharge ink stored in the head cap to, for example, a waste ink tank (e.g., to perform a so-called idle suctioning). However, if the suctioning of ink from the nozzles of the inkjet head and the idle suctioning of ink discharged into the head cap are performed sequentially with respect to a plurality of the head caps, the time required to recover ink ejection performance for the inkjet heads increases. 
     The disclosure relates to a liquid ejection apparatus in which time required to recover a liquid ejection performance may be reduced and a computer-readable medium for controlling the liquid ejection apparatus. 
     According to one aspect of the disclosure, suctioning may be performed in a first state, so that pressure in a capping device, which may be in a sealing state, may be brought into negative pressure at the same time as when liquid remaining in another capping device, which may be in an unsealing state, may be suctioned. As the first state is shifted to a second state, the pressure in the capping device may be promptly reduced to a predetermined negative pressure, as compared with a case in which the pressure in the capping device is not reduced to the negative pressure in advance. Accordingly, the time required to improve liquid ejection performance may be reduced. 
     A liquid ejection apparatus may include a liquid ejection head having a plurality of nozzle units, a plurality of capping devices, a movement mechanism, a plurality of suctioning tubes, a suctioning mechanism, a connection device, and a control device. Each nozzle unit may comprise one or more nozzles for ejecting liquid therefrom. Each capping device may be configured to seal a corresponding nozzle unit of the plurality of nozzle units from an external space. The movement mechanism may be configured to move each capping device relative to the liquid ejection head to place each capping device in a contact state in which the capping device is in contact with the liquid ejection head or a separate state in which the capping device is separated from the liquid ejection head. Each suctioning tube may be connected to a corresponding respective one of the plurality of capping devices. The suctioning mechanism may be configured to suction fluid in the capping device by generating a suctioning force. The connection device may be configured to connect the suctioning mechanism to each of the plurality of suctioning tubes. The control device may control the connection device and the movement mechanism to place the liquid ejection apparatus in a first state in which the suctioning mechanism is connected to a first suctioning tube, of the plurality of suctioning tubes, connected to the capping device corresponding to one of the plurality of nozzle units, to suction fluid in the capping device corresponding to the one of the plurality of nozzle units in an unsealing state in which the one of the plurality of nozzle units is not sealed from the external space, and the suctioning mechanism is connected to a second suctioning tube, of the plurality of suctioning tubes, connected to the capping device corresponding to a different one of the plurality of nozzle units, to suction fluid in the capping device corresponding to the different one of the plurality of nozzle units in a sealing state in which the different one of the plurality of nozzle units is sealed from the external space. The control device may control the suctioning mechanism to suction fluid in the capping device corresponding to the one of the plurality of nozzle units and to suction fluid in the capping device corresponding to the different one of the plurality of nozzle units in the first state. The control device may control the connection device to place the liquid ejection apparatus in a second state in which the first suctioning tube connected to the capping device corresponding to the one of the plurality of nozzle units is disconnected from the suctioning mechanism in response to expiration of a predetermined time period, the predetermined time period being a predetermined amount of time that the suctioning mechanism generates the suctioning force in the first state, wherein the second suctioning tube connected to the capping device corresponding to the different one of the plurality of nozzle units is connected to the suctioning mechanism in the second state. 
     A non-transitory, computer-readable storage medium storing computer-readable instructions therein that, when executed by at least one processor of a liquid ejection apparatus comprising a liquid ejection head comprising a plurality of nozzle units, each nozzle unit comprising one or more nozzles for ejecting liquid therefrom; a plurality of capping devices, each capping device configured to seal a corresponding nozzle unit of the plurality of nozzle units from an external space; a movement mechanism configured to move each capping device relative to the liquid ejection head to place each capping device in a contact state in which the capping device is in contact with the liquid ejection head or a separate state in which the capping device is separated from the liquid ejection head; a plurality of suctioning tubes, each suctioning tube connected to a corresponding respective one of the plurality of capping devices; a suctioning mechanism configured to suction fluid in the capping device by generating a suctioning force; a connection device configured to connect the suctioning mechanism to each of the plurality of suctioning tubes, instruct the liquid ejection apparatus to execute processes may be provided. The processes may comprise: controlling the connection device and the movement mechanism to place the liquid ejection apparatus in a first state in which the suctioning mechanism is connected to a first suctioning tube, of the plurality of suctioning tubes, connected to the capping device corresponding to one of the plurality of nozzle units, to suction fluid in the capping device corresponding to the one of the plurality of nozzle units in an unsealing state in which the one of the plurality of nozzle units is not sealed from the external space, and the suctioning mechanism is connected to a second suctioning tube, of the plurality of suctioning tubes, connected to the capping device corresponding to a different one of the plurality of nozzle units, to suction fluid in the capping device corresponding to the different one of the plurality of nozzle units in a sealing state in which the different one of the plurality of nozzle units is sealed from the external space; controlling the suctioning mechanism to suction fluid in the capping device corresponding to the one of the plurality of nozzle units and to suction fluid in the capping device corresponding to the different one of the plurality of nozzle units in the first state; and controlling the connection device to place the liquid ejection apparatus in a second state in which the first suctioning tube connected to the capping device corresponding to the one of the plurality of nozzle units is disconnected from the suctioning mechanism after expiration of a predetermined time period, the predetermined time period being a predetermined amount of time that the suctioning mechanism generates the suctioning force in the first state, wherein the second suctioning tube connected to the capping device corresponding to the different one of the plurality of nozzle units is connected to the suctioning mechanism in the second state. 
     A method of maintaining a liquid ejection apparatus comprising a liquid ejection head comprising a plurality of nozzle units, each nozzle unit comprising one or more nozzles for ejecting liquid therefrom; a plurality of capping devices, each capping device configured to seal a corresponding nozzle unit of the plurality of nozzle units from an external space; a movement mechanism configured to move each capping device relative to the liquid ejection head to place each capping device in a contact state in which the capping device is in contact with the liquid ejection head or a separate state in which the capping device is separated from the liquid ejection head; a plurality of suctioning tubes, each suctioning tube connected to a corresponding respective one of the plurality of capping devices; a suctioning mechanism configured to suction fluid in the capping device by generating a suctioning force; a connection device configured to connect the suctioning mechanism to each of the plurality of suctioning tubes, and a control device, may be provided. The method may comprise: controlling the connection device and the movement mechanism to place the liquid ejection apparatus in a first state in which the suctioning mechanism is connected to a first suctioning tube, of the plurality of suctioning tubes, connected to the capping device corresponding to one of the plurality of nozzle units, to suction fluid in the capping device corresponding to the one of the plurality of nozzle units in an unsealing state in which the one of the plurality of nozzle units is not sealed from the external space, and the suctioning mechanism is connected to a second suctioning tube, of the plurality of suctioning tubes, connected to the capping device corresponding to a different one of the plurality of nozzle units, to suction fluid in the capping device corresponding to the different one of the plurality of nozzle units in a sealing state in which the different one of the plurality of nozzle units is sealed from the external space; controlling the suctioning mechanism to suction fluid in the capping device corresponding to the one of the plurality of nozzle units and to suction fluid in the capping device corresponding to the different one of the plurality of nozzle units in the first state; and controlling the connection device to place the liquid ejection apparatus in a second state in which the first suctioning tube connected to the capping device corresponding to the one of the plurality of nozzle units is disconnected from the suctioning mechanism after expiration of a predetermined time period, the predetermined time period being a predetermined amount of time that the suctioning mechanism generates the suctioning force in the first state, wherein the second suctioning tube connected to the capping device corresponding to the different one of the plurality of nozzle units is connected to the suctioning mechanism in the second state 
     Other objects, features, and advantages will be apparent to persons of ordinary skill in the art from the following detailed description of the invention and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference now is made to the following description taken in connection with the accompanying drawings. 
         FIG. 1A  is a schematic side sectional view of an inkjet printer according to one or more aspects of the disclosure. 
         FIG. 1B  is a plane view of a nozzle surface of an inkjet head of the inkjet printer. 
         FIG. 2  is a diagram depicting a maintenance unit of the inkjet printer of  FIG. 1A . 
         FIG. 3  is a sectional view of a rotary valve of the maintenance unit of  FIG. 2 , according to an exemplary embodiment. 
         FIG. 4  is a block diagram depicting a hardware configuration of a control device of the inkjet printer of  FIG. 1A . 
         FIG. 5  is a block diagram depicting components of the inkjet printer of  FIG. 1A . 
         FIG. 6  is a flowchart depicting a maintenance operation for the inkjet printer of  FIG. 1A . 
         FIGS. 7A-7C  are diagrams and tables depicting operations of the maintenance unit of  FIG. 2 . 
         FIGS. 8A-8C  are diagrams and tables depicting operations of the maintenance unit of  FIG. 2 . 
         FIG. 9  is a timing chart depicting operations of the maintenance unit of  FIG. 2 . 
         FIGS. 10A and 10B  are sectional views of a rotary valve according to an exemplary embodiment. 
         FIGS. 11A-11C  are diagrams and tables depicting operations of the rotary valve of  FIGS. 10A and 10B . 
         FIG. 12  is a diagram depicting a portion of a modified maintenance unit. 
         FIG. 13  is a diagram depicting a modified rotary valve. 
         FIG. 14  is a diagram depicting a modified maintenance unit. 
         FIG. 15A  is a plane view of a nozzle surface of a modified inkjet head. 
         FIG. 15B  is a diagram depicting a maintenance unit for the modified inkjet head of  FIG. 15A . 
         FIG. 16  is a diagram depicting a modified maintenance unit. 
         FIG. 17  is a timing chart depicting operations of the maintenance unit of  FIG. 16 . 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments are described in detail herein with reference to the accompanying drawings, like reference numerals being used for like corresponding parts in the various drawings. 
     As depicted in  FIG. 1A , an inkjet printer  1  may comprise an upper casing  11  and a lower casing  12 . Each of the upper casing  11  and the lower casing  12  may have a rectangular parallelepiped shape. A front side  3  and a rear side  4  of the printer  1  may be disposed on the left and right sides in  FIG. 1A , respectively. A lower surface of the upper casing  11  may have an opening. An upper surface of the lower casing  12  may have an opening. The upper casing  11  may be pivotally connected to the lower casing  12  about a pivot shaft  13 . The upper casing  11  may pivotally move between a closed position in which an interior space of the printer  1  is defined by making a lower surface of the upper casing  11  contact to an upper surface of the lower casing  12  and an open position in which the interior space of the printer  1  is open. An opening/closing sensor  16  may be fixed on the upper surface of the lower casing  11 . The opening/closing sensor  16  may be configured to output a detection signal when the upper casing  11  is in the closed position and not to output the detection signal when the upper casing  11  is in the open position. The printer  1  may comprise a lock mechanism  14  configured to regulate the pivotal movement of the upper casing  11  when the upper casing  11  is in the closed position. A sheet output portion  15  may be disposed on an upper surface of the upper casing  11 . A sheet P for which printing has been completed may be sequentially output onto the sheet output portion  15 . 
     Six inkjet heads  2 , a sheet tray  20 , a sheet feeding mechanism  30 , a platen  9 , and a maintenance unit  40  may be disposed in the interior space of the printer  1 . 
     As depicted in  FIG. 1B , each inkjet head  2  may have generally a rectangular parallelepiped shape. The inkjet head  2  may have an ejection surface  2   a  on a lower surface thereof. The ejection surface  2   a  may have nozzles  8  from which ink droplets may be ejected. Ink may be supplied from an ink tank (not depicted) to the inkjet head  2 . Ink supplied to the inkjet head  2  may reach the nozzles  8 , via a common ink chamber and pressure chambers that may fluidly communicate with the common ink chamber. Actuators (not depicted) configured to apply pressure to ink stored in the pressure chambers may be disposed in an interior of the inkjet head  2 . As the actuators are driven, ink droplets may be ejected from the nozzles  8 . 
     Each of the six inkjet heads  2  may correspond to one of different ink types, e.g., colors, of e.g., yellow, light cyan, light magenta, cyan, magenta and black. The inkjet heads  2  corresponding to yellow, light cyan, light magenta, cyan, magenta and black ink colors may be arranged in this order from an upstream side in a feeding direction of the sheets P. In the example embodiment, each inkjet head  2  may correspond to one of different ink type. In another embodiment, a plurality of the inkjet heads  2  may correspond to one ink type, or one inkjet head  2  may correspond to a plurality of ink types. 
     The sheet tray  20  may be configured to hold a stack of the sheets P. The sheet tray  20  may be removably disposed on a bottom surface of the lower casing  12 . 
     The platen  9  may comprise a plate member configured to support the sheets P. The platen  9  may be fixed to the lower casing  12  to oppose the ejection surfaces  2   a  of the inkjet heads  2  when the upper casing  11  is in the closed position. Sizes of the platen  9  in a main scanning direction and a sub scanning direction may be slightly larger than the sizes of the ejection surfaces  2   a  of the six inkjet heads  2 . 
     The sheet feeding mechanism  30  may comprise a feeding path for the sheets P from the sheet tray  20  to the sheet output portion  15  through a portion between the six inkjet heads  2  and the platen  9 . The sheet feeding mechanism  30  may further comprise a pickup roller  31 , nip rollers  32   a - 32   e , and guides  33   a - 33   d . The pickup roller  31  may be configured to pick up and feed an uppermost sheet P from a stack of the sheets P on the sheet tray  20 . The nip rollers  32   a - 32   e  may be disposed along the feeding path. The nip rollers  32   a - 32   e  may apply feeding force to the sheet P. The guide  33   a  may be disposed between the pickup roller  31  and the nip roller  32   a  in the feeding path. The guide  33   a  may be configured to guide the sheet P until the sheet P having feeding force applied thereto by the pickup roller  31  is fed to the next nip rollers  32   a . Similarly, the guide  33   b ,  33   c , and  33   d  may be disposed between the nip rollers  32   a  and  32   b ,  32   c  and  32   d , and  32   d  and  32   e  in the feeding path, respectively. The guides  33   b - 33   d  may be configured to guide the sheet P until the sheet P having feeding force applied thereto by the nip roller  32   a ,  32   c , and  32   d  is fed to the next nip roller  32   b ,  32   d , and  32   e . When the sheet P fed by the sheet feeding mechanism  30  passes between the six inkjet heads  2  and the platen  9 , an image may be printed on the sheet P by the ink droplets ejected from the ejection surface  2   a  having the nozzles  8  of each inkjet head  2 . The sheet P having an image printed thereon may be fed by the sheet feeding mechanism  30  in the feeding direction and output to the sheet output portion  15 . 
     As depicted in  FIGS. 1A and 2 , the maintenance unit  40  may be configured to perform a maintenance operation to recover, e.g., clogging of the nozzles  8  of the inkjet heads  2 . The maintenance operation may comprise a purge operation in which ink may be forcibly discharged from the nozzles  8 . The maintenance unit  40  may comprise six cap members  41 , an elevation mechanism  42 , six suction tubes  43 , a pump  44 , a waste liquid tube  45 , a rotary valve  46 , and a waste liquid tank  51 . 
     Each of the six cap members  41  may comprise an elastic member configured to seal the nozzles  8  of the corresponding inkjet head  2  from an external space, e.g., the atmosphere. Each cap member  41  may comprise a recess portion  41   a  having an open end facing upward so as to allow the ejection surface  2   a  to be surrounded. Each cap member  41  may have an annular shape. When an upper end of the recess portion  41   a  contacts the ejection surface  2   a , the recess portion  41   a  may be placed in a sealing state in which all nozzles  8  of the corresponding inkjet head  2  may be sealed from the external space (refer to the leftmost cap member  41  in  FIG. 2 ). When the upper end of the recess portion  41   a  is separated from the ejection surface  2   a , the recess portion  41   a  may be placed in an unsealing state, e.g., an open state, in which the nozzles  8  may be open to the external space (refer to the cap members  41  other than the leftmost cap member  41  in  FIG. 2 ). 
     The elevation mechanism  42  may support the six cap members  41  that may be arranged in one direction. The elevation mechanism  42  may be configured to move each of the six cap members  41  up and down relative to the respective ejection surfaces  2   a , such that the cap members  41  may be independently placed in the sealing state or the open state. When the printer  1  is on standby for printing, the elevation mechanism  42  may move behind the platen  9 , e.g., backward with respect to the sheet of  FIG. 1A , so as not to oppose the ejection surface  2   a . When the maintenance operation is performed, the elevation mechanism  42  may be moved by a movement mechanism (not depicted) to a maintenance position in which the cap members  41  oppose the corresponding the ejection surfaces  2   a . The maintenance operation may comprise a sealing operation to prevent or reduce drying of the nozzles  8  by sealing the ejection surfaces  2   a  with the cap members  41 , in addition to the purge operation. The elevation mechanism  42  may be configured to move each one of cap members  41  up and down relative to the respective ejection surfaces  2   a . In addition, the elevation mechanism  42  may be configured to move two or more cap members  41  simultaneously up and down relative to the respective ejection surfaces  2   a.    
     The pump  44  may be configured to suction fluid, e.g., air or ink, in the recess portions  41   a  of the cap members  41 . The pump  44  may be configured to generate suction force. The rotary valve  46  may be configured to bring one or two cap members  41  among the six cap members  41  into communication with the pump  44 . The waste liquid tank  51  may be configured to store waste ink discharged from the nozzles  8  of the inkjet heads  2 . The purge operation in which a relatively large amount of ink is forcibly discharged from the nozzles  8  and a flushing operation in which ink droplets are ejected from the nozzles  8  may generate the waste ink. Each of the six suction tubes  43  may be connected to the corresponding one of the recess portions  41   a  of the cap members  41  at one end and to the rotary valve  46  at the other end. The waste liquid tube  45  may be connected to the rotary valve  46  at one end and to the waste liquid tank  51  at the other end. The waste liquid tube  45  may be connected to the pump  44 . 
     As depicted in  FIGS. 2 and 3 , the rotary valve  46  may comprise a rotation shaft, a casing  55  having a hollow cylindrical shape and a rotation member  56  disposed in an internal space  55   b  of the casing  55 . The rotation member  56  may have a cylindrical shape. The rotation member  56  may be configured to rotate inside the internal space  55   b  along a circumferential direction of the casing  55 . The casing  55  may have seven communication openings  55   a  through which the internal space  55   b  may be brought into communication with the external space. Among the seven communication openings  55   a , one of the six communication openings  55   a  disposed on an outer peripheral surface of the casing  55  along the circumferential direction may correspond to different one of ports A-F. The communication opening  55   a  formed at a central portion of an end face of the casing  55  may correspond to a port G. The suction tubes  43  may be connected to the ports A-F. The waste liquid tube  45  may be connected to the port G. 
     The rotation member  56  may have a first flow path  56   a  and a second flow path  56   b  that extend from the outer peripheral surface of the casing  55  to the rotation shaft along a radial direction of the casing  55 , and a third flow path  56   c  that extends along the rotation shaft and brings the first and second flow paths  56   a  and  56   b  into communication with the port G. The second flow path  56   b  may become wider in the circumferential direction of the casing  55 , as the second flow path  56   b  extends closer to the outer peripheral surface of the casing  55 . Accordingly, a cross-sectional area of the passage of the first flow path  56   a  may be smaller than that of the passage of the second flow path  56   b . Among the ports A-F, the first and second flow paths  56   a ,  56   b  may sequentially communicate with one of the adjacent two ports A-F, both of the adjacent two ports A-F, and the other one of the two adjacent ports A-F, as the rotation member  56  rotates in one direction. For example, the second flow path  56  may be connected to one of the adjacent two ports A-F. Then, each of the first and second flow paths  56   a  may be connected to different one of the adjacent two ports A-F. Then, the second flow path  56  may be connected to the other one of the adjacent two ports A-F. As will be described below, when the first flow path  56   a  is connected to one of the ports A-F, the recess portion  41   a  corresponding to the one of the ports A-F may be placed in the open state. When the second flow path  56   b  is connected to one of the ports A-F, the recess portion  41   a  corresponding to that the one of the ports A-F may be placed in the sealing state. At this time, the one or two recess portion(s)  41   a  corresponding to the one or two port(s) A-F connected to the first flow path  56   a  and/or the second flow path  56   b  may be connected to the port G (i.e., the pump  44 ). A motor (not depicted) may control the rotational position of the rotation member  56 . 
     As depicted in  FIG. 4 , the control device  1   p  may comprise a central processing unit (CPU)  71 , an electrically erasable and programmable read only memory (EEPROM)  72  configured to rewritably store programs, e.g., computer-readable instructions, to be executed by the CPU  71  and data to be used by the programs, a random access memory (RAM)  73  configured to temporarily store data when programs are executed, an I/F circuit  74  configured to perform communication with an external device, e.g., a PC  90 , and an I/O circuit  75  connected to a touch panel  76  and various sensors (not depicted). The CPU  71 , the EEPROM  72 , the RAM  73 , the I/F circuit  74  and the I/O circuit  75  may be interconnected via data buses  81 . A print controller  61 , a maintenance controller  62 , and a display controller  63 , as depicted in  FIG. 5 , of the control device  1   p  may be constructed in cooperation with the hardware  71 - 75  and software, e.g., computer-readable instructions, stored in the EEPROM  72 . 
     As depicted in  FIG. 5 , the control device  1   p  may comprise the print controller  61 , the maintenance controller  62 , and the display controller  63 . The print controller  71  may be configured to control the inkjet heads  2  and the sheet feeding mechanism  30  such that a desired image is printed on the sheet P. The display controller  63  may be configured to control the touch panel  76 . The maintenance controller  62  may be configured to control the elevation mechanism  42 , the rotary valve  46  and the pump  44  such that the maintenance operation including the purge operation is executed. The purge operation may comprise a suctioning operation, an idle suctioning operation, and a preliminary suctioning operation. In a suctioning operation, fluid in the recess portion  41   a  of one cap member  41  that is placed in the sealing state may be suctioned. In the idle suctioning operation, fluid in the recess portion  41   a  of the one cap member  41  that is placed in the open state may be suctioned. In the preliminary suctioning operation, at the same time when the idle suctioning operation is performed for the one cap member  41 , fluid in the recess portion  41   a  of the another cap members  41  that is placed in the sealing state may be suctioned. 
     As depicted in  FIG. 6 , when the purge operation is started, the maintenance controller  62  may move the elevation mechanism  42  such that each of the recess portions  41   a  of the cap members  41  may oppose the corresponding ejection surface  2   a  of the inkjet head  2  (S 101 ). The maintenance controller  62  may control the elevation mechanism  42  to bring all cap members  41  in the sealing state (S 102 ). Thus, the nozzles  8  may be sealed to prevent or reduce the drying of the nozzles  8 . The maintenance controller  62  may rotate the rotation member  56  to connect the port A and the second flow path  56   b , as depicted in  FIG. 7A , to perform the suctioning operation for the inkjet head  2  corresponding to the port A. Accordingly, the recess portion  41   a  of the cap member  41 , that is placed in the sealing state, corresponding to the port A may communicate with the pump  44 . In this state, as the pump  44  is driven for a predetermined time, the suctioning operation may be executed. Accordingly, ink may be purged into the recess portion  41   a  corresponding to the port A from the nozzles  8  of the inkjet head  2  that is sealed by the recess portion  41   a  corresponding to the port A (S 103 ). 
     The maintenance controller  62  may simultaneously perform the idle suctioning operation for one inkjet head  2  and the preliminary suctioning operation for another inkjet head  2 . More specifically, the idle suctioning may be performed by placing the cap member  41  corresponding to the inkjet head  2  for which the suctioning operation has been just performed, in the open state. With the cap member  41  in the open state, ink stored in recess portion  41   a  during the suctioning operation may be suctioned during the idle suctioning operation. At the same time when the idle suctioning operation is performed, the preliminary suctioning operation may be performed, prior to the suctioning operation, for another inkjet head  2  for which the suctioning operation is to be performed next, by placing the cap member  41  corresponding to another inkjet head  2  in the sealing state (S 104 ). For example, the maintenance controller  62  may control the elevation mechanism  42  to bring the cap member  41  corresponding to the port A to the open state from the sealing state, and to maintain the cap members  41  corresponding to the port B in the sealing state (a first sealing state). Further, the maintenance controller  62  may rotate the rotation member  56  counterclockwise to connect the ports A and B to the first flow path  56   a  and the second flow path  56   b , respectively (the first state), as depicted in  FIG. 7B . Accordingly, the two recess portions  41   a  of the cap members  41  corresponding to the ports A and B may communicate with the pump  44  that is being driven. Accordingly, the idle suctioning operation may be performed for the recess portion  41   a  of the cap member  41 , that is placed in the open state, corresponding to the port A. The preliminary suctioning operation may be performed for the recess portion  41   a  of the cap member  41 , that is placed in the sealing state, corresponding to the port B. 
     The maintenance controller  62  may wait until the elapsed time since the idle suctioning operation has been started becomes equal to time t 1  (S 105 : NO). The time t 1  may be the time for which the idle suctioning operation may be continued. More specifically, the time t 1  may be longer than or equal to the time required to suction all of the maximum amount of ink that the recess portion  41   a  of the cap member  41  to be subjected to the idle suctioning operation is able to store therein. Accordingly, ink remaining in the recess portion  41   a  may be reliably discharged. As depicted in  FIG. 9 , while the idle suctioning operation is performed to suction ink remaining in the recess portion  41   a  corresponding to the port A, internal pressures of the recess portions  41   a  corresponding to the ports A and B may be reduced. Thereafter, as the ink remaining in the recess portion  41   a  corresponding to the port A is all suctioned, the port A may communicate with the atmosphere, so that the internal pressures of the recess portions  41   a  corresponding to the ports A and B may increase. However, the pump  44  may continue to suction fluid, e.g., the air, so that a certain negative pressure may be maintained. 
     When the maintenance controller  62  determines that the elapsed time becomes equal to the time t 1  (S 105 : YES), the maintenance controller  62  may determine whether the idle suctioning operation is completed for all of the inkjet heads  2  (S 106 ). When the maintenance controller  62  determines that the idle suctioning operation is completed for all of the inkjet heads  2  (S 106 : YES), the maintenance controller  62  may place all cap members  41  in the open state (S 109 ). Thereafter, the maintenance controller  62  may move the elevation mechanism  42  to a position where the elevation mechanism  42  does not oppose the ejection surface surfaces  2   a  (S 110 ). Then, the purge operation may end. 
     When the maintenance controller  62  determines that the idle suctioning operation is not completed for all of the inkjet heads  2  (S 106 : NO), the maintenance controller  62  may continue the purge operation for the next inkjet head  2  (S 107 ). The maintenance controller  62  may control the elevation mechanism  42  to bring the cap member  41  corresponding to the port A to the sealing state from the open state and to maintain the cap members  41  corresponding to the port B in the sealing state. As depicted in  FIG. 7C , the maintenance controller  62  may rotate the rotation member  56  counterclockwise to maintain the connection between the port B and the second flow path  56   b  while the port A is blocked (the second state). Accordingly, the recess portion  41   a  of the cap member  41 , that is placed in the sealing state, corresponding to the port B may communicate with the pump  44  that is being driven. The suctioning operation may be started to purge ink from the nozzles  8  of the inkjet head  2  sealed by the recess portion  41   a . At this time, pressure in the recess portion  41   a  corresponding to the port B may be maintained in the negative pressure by the preliminary suctioning operation that may be preliminary performed before the suctioning operation, as depicted in  FIG. 9 . Therefore, the pressure in the recess portion  41   a  corresponding to the port B may be promptly reduced to the desired negative pressure with the reduced time, as compared with a case in which the preliminary suctioning operation is not performed (refer to broken lines in  FIG. 9 ). Accordingly, ink may be effectively purged from the nozzles  8  of the inkjet head  2  sealed by the recess portion  41   a  corresponding to the port B. Then, the maintenance controller  62  may wait until the elapsed time since the suctioning operation has been started becomes equal to time t 2  (S 108 : NO). The time t 2  may correspond to the time in which the ink ejection performance of the nozzles  8  of the inkjet head  2  may be recovered by the purge operation. 
     When the maintenance controller  62  determines that the elapsed time becomes equal to the time t 2  (S 108 : YES), the idle suctioning operation may performed for the recess portion  41   a  for which the suctioning operation has been just performed, in the procedure as described above. At the same time, the preliminary suctioning operation may be performed for the recess portion  41   a  corresponding to the next inkjet head  2 , if any. The above-described steps S 104 -S 108  may be repeated for the ports B and C, the ports C and D, the ports D and E, and the ports E and F (refer to  FIGS. 8A and 8B ) to sequentially perform the preliminary suctioning operation, the suctioning operation and the idle suctioning operation for the inkjet heads  2  corresponding to the ports C-F. As depicted in  FIG. 8C , for the inkjet head  2  corresponding to the port F, the idle suctioning operation may be performed independently without the preliminary suctioning operation being performed at the same time (S 104 ). In the example embodiment, when the idle suctioning operation for the inkjet head  2  corresponding to the port F is completed, the maintenance controller  62  may determine that the idle suctioning operation is completed for all of the inkjet heads  2  (S 106 : YES), the maintenance controller  62  may place all cap members  41  in the open state (S 109 ), and then move the elevation mechanism  42  to a position where the elevation mechanism  42  does not oppose the ejection surfaces  2 . Then, the purge operation may end (S 110 ). 
     The printer  1  according to the example embodiment may perform suctioning in the first state, so that the preliminary suctioning operation may be performed to bring the pressure in the recess portion  41   a  of the cap member  41 , which is to be subjected to the suctioning operation, to negative pressure, at the same time as the idle suctioning operation. As the preliminary suctioning operation is shifted to the suctioning operation, the pressure in the recess portion  41   a  may be promptly reduced to the predetermined negative pressure, as compared with a case in which the recess portion  41   a  is not reduced to negative pressure in advance before the suctioning operation is performed. Accordingly, ink may be effectively purged, and the time required to recover ink ejection performances may be reduced. 
     The time t 1  for which the idle suctioning operation may be continued may be the time longer than or equal to the time required to suction all of the maximum amount of ink that the recess portion  41   a  of the cap member  41  to be subjected to the idle suctioning operation is able to store therein. Therefore, ink remaining in the recess portion  41   a  may be reliably discharged from the recess portion  41   a.    
     Further, with the use of the rotary valve  46 , connections between the six suction tubes  43  and the waste liquid tube  45  may be readily arranged and reduction of the size of the printer  1  may be achieved. 
     In the rotation member  56  of the rotary valve  46 , a cross-sectional area of the passage of the first flow path  56   a  may be smaller than that of the passage of the second flow path  56   b . Therefore, in the preliminary suctioning operation, the pressure in the recess portion  41   a  that communicates with the second flow path  56   b  may be effectively brought to negative pressure. 
     The cap members  41 , other than one cap member  41  for which the idle suctioning operation is being performed, may be placed in the sealing state. Therefore, drying of the nozzles  8  may be prevented or reduced. 
     A difference of the second example embodiment from the first example embodiment may be a rotary valve  146 . Structures and operations of the rotary valve  146  are described below referring to  FIGS. 10A-11C . Like reference numerals may be used for like corresponding components in  FIGS. 10A-11C  and a detailed description thereof with respect to the second example embodiment may be omitted herein. 
     The rotary valve  146  may comprise the rotation shaft, the casing  55  having a hollow cylindrical shape and the rotation member  56  disposed in the internal space  55   b  of the casing  55 . The rotation member  56  may have a cylindrical shape. The rotation member  56  may be configured to rotate inside the internal space  55   b  along the circumferential direction of the casing  55 . The casing  55  may have seven communication openings  55   a  through which the internal space  55   b  may be brought into communication with an external space, e.g., the atmosphere. Among the seven communication openings  55   a , one of the six communication openings  55   a  disposed equiangularly at the central angle of 60 degrees on an outer peripheral surface of the casing  55  along the circumferential direction may correspond to the different one of the ports A-F. The communication opening  55   a  formed at a central portion of an end face of the casing  55  may correspond to the port G. The suction tubes  43  may be connected to the ports A-F. The waste liquid tube  45  may be connected to the port G. 
     The rotation member  56  may have six communication paths  156   aa ,  156   ab ,  156   ba ,  156   bb ,  156   ca , and  156   cb  that extend from the outer peripheral surface of the casing  55  to the rotation shaft along the radial direction of the casing  55 , and a communication path  156   d  that extends along the rotation shaft and brings the communication paths  156   aa ,  156   ab ,  156   ba ,  156   bb ,  156   ca , and  156   cb  into communication with the port G. The communication paths  156   aa  and  156   ab , the communication paths  156   ba  and  156   bb , and the communication paths  156   ca  and  156   cb  may be paired. The communication paths  156   aa  and  156   ab  may be separated apart by the central angle of 60 degrees with respect to the circumferential direction. The communication paths  156   ba  and  156   bb  may be separated apart by the central angle of 120 degrees with respect to the circumferential direction. The communication path  156   ca  and  156   cb  may be separated apart by the central angle of 180 degrees with respect to the circumferential direction. As each communication path  156   aa ,  156   ab ,  156   ba ,  156   bb ,  156   ca , and  156   cb  extends closer to the outer peripheral surface of the casing  55 , each of the communication paths  156   aa - 156   cb  may become wider in the circumferential direction so as to expand toward a side away from the other one of the communication paths  156   aa - 156   cb  in one pair  156   aa  and  156   ab ;  156   ba  and  156   bb ; and  156   ca  and  156   cb . One pair of the communication paths  156   aa  and  156   ab ;  156   ba  and  156   bb ; and  156   ca  and  156   cb  may be separated apart from the other pairs of the communication paths  156   aa  and  156   ab ;  156   ba  and  156   bb ; and  156   ca  and  156   cb , at a central angle other than 60 degrees with respect to the circumferential direction. 
     Among the ports A-F, the communication paths  156   aa  and  156   ab ;  156   ba  and  156   bb ;  156   ca  and  156   cb  may sequentially communicate with one of the arbitrarily selected two ports A-F, both of the arbitrarily selected two ports A-F, and the other one of the arbitrarily selected two ports A-F, as the rotation member  56  rotates in one direction. For example, one of one pair of the communication paths  156   aa  and  156   ab ;  156   ba  and  156   bb ;  156   ca  and  156   cb  may communicate with one of the arbitrarily selected two ports A-F. Then, each of the one pair of the communication paths  156   aa  and  156   ab ;  156   ba  and  156   bb ;  156   ca  and  156   cb  may communicate with different one of the arbitrarily selected two ports A-F. Then, the other one of the one pair of the communication paths  156   aa  and  156   ab ;  156   ba  and  156   bb ;  156   ca  and  156   cb  may communicate with the other one of the arbitrarily selected two ports A-F. The ports A-F may be equiangularly disposed at the central angle of 60 degrees. Therefore, any of the two selected ports A-F may be separated apart at any one of the central angle of 60 degrees, 120 degrees, and 180 degrees. Any pair of the communication paths  156   aa  and  156   ab ;  156   ba  and  156   bb ,  156   ca  and  156   cb  may be used for connection to one or two ports A-F. One pair of the communication paths  156   aa  and  156   ab ;  156   ba  and  156   bb ; and  156   ca  and  156   cb  may be separated apart from the other pairs of the communication paths  156   aa  and  156   ab ;  156   ba  and  156   bb ; and  156   ca  and  156   cb , at a central angle other than 60 degrees with respect to the circumferential direction. Therefore, the other pairs of the communication paths  156   aa  and  156   ab ;  156   ba  and  156   bb ,  156   ca  and  156   cb  might not be connected to the other ports A-F. 
     For example, as depicted in  FIG. 10A , when the ports A and D, which are separated apart at the central angle of 180 degrees, are brought into communication with the pump  44 , a pair of the communication paths  156   ca  and  156   cb  separated apart at the central angle of 180 degrees may be connected to the ports A and D. In  FIG. 10A , the communication path  156   ca  may be connected to the port A and the communication path  156   cb  may be connected to the port D. As depicted in  FIG. 10B , when the ports A and E, which are separated apart at the central angle of 120 degrees, are brought into communication with the pump  44 , a pair of the communication paths  156   ba  and  156   bb  separated apart at the central angle of 120 degrees may be connected to the ports A and E. In  FIG. 10B , the communication path  156   bb  may be connected to the port A, and the communication path  156   ba  may be connected to the port E. Further, when the ports A and B, which are separated apart at the central angle of 60 degrees, are brought into communication with the pump  44 , a pair of the communication paths  156   aa  and  156   ab  separated apart at the central angle of 60 degrees may be connected to the ports A and B. In  FIG. 11B , the communication path  156   aa  may be connected to the port A, and the communication path  156   ab  may be connected to the port B. 
     In the example embodiment, the purge operation may be performed for every two inkjet heads  2  that are arbitrarily selected. For example, when the two inkjet heads  2  that are selected for the purge operation correspond to the ports A and B, the maintenance controller  62  may control the elevation mechanism  42  to bring the cap member  41  corresponding to the port B in the sealing state. As the maintenance controller  62  rotates the rotation member  56  to bring the port B into communication with the pump  44  and to block other ports A and C-F, as depicted in  FIG. 11A , the communication path  156   ab  may be connected to the port B. At this time, the communication path  156   aa  may be disposed on the side opposite to the port A in a clockwise direction. Accordingly, the recess portion  41   a  of the cap member  41 , placed in the sealing state, corresponding to the port B may communicate with the pump  44 . In this state, the pump  44  may be driven for the predetermined time to perform the suctioning operation. Thus, ink may be purged from the nozzles  8  of the inkjet head  2  sealed by the recess portion  41   a  corresponding to the port B, into the recess portion  41   a  corresponding to the port B. 
     Further, the maintenance controller  62  may control the elevation mechanism  42  to bring the cap member  41  corresponding to the port B to the open state from the sealing state, and to maintain the cap member  41  corresponding to the port A in the sealing state (the first sealing state). The maintenance controller  62  may rotate the rotation member  56  clockwise to connect the ports A and B to the communication paths  156   aa  and  156   ab , respectively, as depicted in  FIG. 11B  (the first state). Accordingly, the two recess portions  41   a  of the cap members  41  corresponding to the ports A and B may communicate with the pump  44  that is being driven. Accordingly, the idle suctioning operation may be performed for the recess portion  41   a  of the cap member  41 , that is place in the open state, corresponding to the port B. The preliminary suctioning operation may be performed for the recess portion  41   a  of the cap member  41 , that is placed in the sealing state, corresponding to the port A. 
     The maintenance controller  62  may wait until the elapsed time since the idle suctioning operation has been started becomes equal to time t 1 ′. The time t 1 ′ may be the time for which the idle suctioning operation may be continued. More specifically, the time t 1 ′ may be less than or equal to the time required to suction all of the maximum amount of ink that the recess portion  41   a  of the cap member  41  to be subjected to the idle suctioning operation is able to store therein. Accordingly, while ink remaining in the recess portion  41   a  corresponding to the port B is suctioned by the idle suctioning operation, the internal pressures of the recess portions  41   a  corresponding to the ports A and B may be reduced. The idle suctioning operation may stop before all amounts of ink remaining in the recess portion  41   a  corresponding to the port B are suctioned. Accordingly, negative pressure may be maintained in the recess portion  41   a  corresponding to the port A. 
     When the maintenance controller  62  determines that the elapsed time becomes equal to the time t 1 ′, the maintenance controller  62  may control the elevation mechanism  42  to place the cap members  41  corresponding to the ports A and B in the sealing state. As depicted in  FIG. 11C , the maintenance controller  62  may rotate the rotation member  56  clockwise to connect the port A to the communication path  156   aa  while the port B is blocked. Accordingly, the recess portion  41   a  of the cap members  41 , placed in the sealing state, corresponding to the port A may communicate with the pump  44  that is being driven. The suctioning operation may be started to purge ink from the nozzles  8  of the inkjet head  2  sealed by the recess portion  41   a  corresponding to the port A. At this time, pressure in the recess portion  41   a  corresponding to the port A may be maintained in the negative pressure by the preliminary suctioning operation that may be preliminary performed before the suctioning operation. Therefore, the pressure in the recess portion  41   a  corresponding to the port A may be promptly reduced to the desired negative pressure with the reduced time, as compared with a case in which the preliminary suctioning operation is not performed. Accordingly, ink may be effectively purged from the nozzles  8  of the inkjet head  2  sealed by the recess portion  41   a  corresponding to the port A. 
     Thereafter, when the elapsed time since the suctioning operation has been started becomes equal to the time t 2 , the maintenance controller  62  may control the elevation mechanism  42  to bring the cap member  41  corresponding to the port A to the open state from the sealing state for the idle suctioning operation to be performed after the suctioning operation. At this time, the pump  44  may communicate with one inkjet head  2 , corresponding to the port A, that may be subjected to the idle suctioning operation, so that ink remaining in the recess portion  41   a  corresponding to the port A may be effectively suctioned. As a predetermined time has elapsed since the idle suctioning operation has been started to complete suctioning of the ink remaining in the recess portion  41   a , the maintenance controller  62  may stop driving the pump  44 . The maintenance controller  62  may place all cap members  41  in the open state, and then move the elevation mechanism  42  to a position where the elevation mechanism  42  does not oppose the ejection surfaces  2 . Then, the purge operation may end. 
     The printer  1  according to the example embodiment may perform suctioning in the first state, so that the preliminary suctioning operation may be performed at the same time as the idle suctioning operation, to bring the pressure in the recess portion  41   a  of the cap member  41 , which is to be subjected to the suctioning operation, to negative pressure. As the preliminary suctioning operation is shifted to the suctioning operation, the pressure in the recess portion  41   a  may be promptly reduced to the predetermined negative pressure, as compared with a case in which pressure in the recess portion  41   a  is not reduced to negative pressure in advance before the suctioning operation is performed. Accordingly, ink may be effectively purged, and the time required to recover ink ejection performances may be reduced. 
     The time t 1 ′ for which the idle suctioning operation may be continued may be the time less than or equal to the time required to suction all of the maximum amount of ink that the recess portion  41   a  of the cap member  41  to be subjected to the idle suctioning operation is able to store therein. Therefore, negative pressure may be maintained in the recess portion  41   a  subjected to the preliminary suctioning operation. 
     Further, in the purge operations for the arbitrarily selected two inkjet heads  2 , the pump  44  may communicate with one port corresponding to the second or last inkjet head  2  subjected to the idle suctioning operation. Therefore, ink remaining in the recess portion  41   a  corresponding to the one port may be effectively suctioned. 
     The purge operation may be performed for the two inkjet heads  2  that are arbitrarily selected. Therefore, the purge operation may be effectively performed as necessary, to reduce the consumption of ink. 
     In the above-described example embodiments, an end of the cap member  41  may contact the ejection surface  2   a  (contact state) to bring the cap member  41  in the sealing state. The end of the cap member  41  may be separated from the ejection surface  2   a  (separate state) to bring the cap member  41  in the open state. Alternatively, the state of the cap member  41  may be changed between the sealing state or contact and the open state or separate state with other construction. For example, as depicted in  FIG. 12 , the cap member  41  may have an air communication path  241   b  formed at a side wall thereof. The air communication path  241   b  may communicate with the air. The cap member  41  may comprise a valve  246   a  configured to open or close the air communication path  241   b . With such a structure, the valve  246   a  may be open or closed with the cap member  41  contacting the ejection surface  2   a , to change the state of the cap member  41  between the sealing state and the open state promptly. That is, in this case, even in the contact state in which the cap member  41  is in contact with the ejection surface  2   a , when the valve  246   a  is closed, it may be in the sealing state, and when the valve  246   a  is opened, it may be in the open state. 
     As depicted in  FIG. 13 , an outer peripheral surface of a casing  355  of a rotary valve  346  may have an air communication opening  355   a  at a position adjacent to each communication opening  55   a . A rotation member  356  of the rotary valve  346  may have an air communication path  356   c  that may connect the first flow path  56   a  to the air communication opening  355   a . The recess portion  41   a  connected to the communication opening  55   a  may communicate with the atmosphere, even with the cap member  41  contacting the ejection surface  2   a . The control of the elevation mechanism  42  may be simplified. The cross-sectional area of the passage of the air communication opening  355   a  may be set smaller than that of the passage of the first flow path  56   a , so that the suctioning efficiency in the preliminary suctioning operation may increase. 
     In the above-described example embodiments, the rotary valve  46 ,  146 ,  346  may be used as a connection device. Alternatively, as depicted in  FIG. 14 , an opening/closing valve  446  may be provided for each of the suction tubes  43 , instead of the rotary valve  46 ,  146 ,  346 . The maintenance controller  62  may control the opening/closing valves  446  independently to operate similar to the rotary valve  46 ,  146 ,  346 . 
     In the above-described example embodiment, each inkjet head  2  may be configured to eject ink droplets of different types, e.g., colors. Alternatively, the number of the inkjet heads  2  might not correspond to the number of the types of ink droplets to be ejected. For example, as depicted in  FIG. 15A , one inkjet head  502  may be configured to eject ink droplets of six types. With such a structure, six nozzle unit blocks  509 , each of which comprising the nozzles  8 , may be disposed along the main scanning direction. Each of the nozzle unit blocks  509  may comprise rows of the nozzles  8  according to ink types. As depicted in  FIG. 15B , the cap members  41  may seal the nozzles  8  of the corresponding nozzle unit blocks  509 . In the above-described example embodiments, the cap members  41  may be arranged in the sub scanning direction. In this modification, the cap members  41  may be arranged in the main scanning direction. 
     As depicted in  FIG. 16 , a check valve  91  may be provided for each of the six suction tubes  43  in the above-described example embodiment. The check valve  91  may be configured to regulate the movement of fluid from the rotary valve  46  to the corresponding cap member  41 . In the construction of  FIG. 16 ,  FIG. 17  may correspond to  FIG. 9 . When the check valves  91  are provided, pressure in the recess portion  41   a  corresponding to the port B might not increase during the preliminary suctioning operation, as depicted in  FIG. 17 . As compared with a case depicted in  FIG. 9  in which the check valves  91  are not provided, pressure in the recess portion  41   a  corresponding to the port B may be reduced more promptly to the desired negative pressure. Consequently, the time t 2  of  FIG. 9  may be reduced to time t 3 . Thus, the time in which the ink ejection performance of the nozzles  8  of the inkjet head  2  is recovered may further be reduced. 
     While the disclosure has been described in detail with reference to the specific embodiments thereof, this is merely an example, and various changes, arrangements and modifications may be applied therein without departing from the spirit and scope of the disclosure. 
     For example, in the above-described example embodiments, the rotation member  56  may be disposed in the internal space  55   b , having a hollow cylindrical shape, of the casing  55 . The rotation member  56  may be configured to rotate inside the internal space  55   b  along the circumferential direction of the casing  55 . The shape of the internal space  55   b  of the casing  55  may have any shape if the rotation member  56  may be rotatable inside the internal space  55   b . For example, a rotation member having a spherical shape may be configured to rotate inside an interior space of a casing having the spherical shape. 
     In the first example embodiment, in the rotation member  56  of the rotary valve  46 , a cross-sectional area of the passage of the first flow path  56   a  may be smaller than that of the passage of the second flow path  56   b . Alternatively, a cross-sectional area of the passage of the first flow path  56   a  may be greater or equal to a cross-sectional area of the passage of the second flow path  56   b.    
     Further, in the first example embodiments, the maintenance controller  62  may simultaneously start the idle suctioning operation for one inkjet head  2  and the preliminary suctioning operation for another inkjet head  2 . Alternatively, the maintenance controller  62  may start the preliminary suctioning operation for another inkjet head  2  after starting the idle suctioning operation for one inkjet head  2 . 
     The second flow path  56   b  of the rotation member  56  according to the first example embodiment and the communication path  156   aa - 156   cb  of the rotation member  56  according to the second example embodiment may be wider in the circumferential direction of the casing  55  as they extend closer to the outer peripheral surface of the casing  55 . Alternatively, the paths  56   b , and  156   aa - 156   cb  may have any shape. For example, the paths  56   b , and  156   aa - 156   cb  may extend in a uniform width. 
     Further, in the first and second example embodiments, the ports A-F may be arranged along the outer peripheral surface of the casing  55  at the same height or level. The ports A-F may be disposed in any positional relation. For example, any of the ports A-F may be disposed at a different position in a direction perpendicular to the circumferential direction of the casing  55 . 
     In the first example embodiment, the time t 1  may be greater than or equal to the time required to suction the entire maximum amount of ink that the recess portion  41   a  of the cap member  41  to be subjected to the idle suctioning operation is able to store therein. Alternatively, the time t 1  may include the time required to suction all amounts of ink in the suction tubes  43  and the waste liquid tube  45 , as well. When ink remains in the suction tubes  43  or the waste liquid tube  45  during suctioning, ink adhering to the suction tubes  43  or the waste liquid tube  45  may close or clog the tubes  43 ,  45  with the passage of time. Therefore, as the time t 1  is set to the time required to suction all amounts of ink existing in the suction tubes  43  or the waste liquid tube  45  as well, such possibilities that the suction tube  43  or the waste liquid tube  45  is closed or clogged may be reduced. 
     In the example embodiments, the control device  1   p  may comprise the CPU  71 . In another embodiment, the control device  1   p  may comprise one or more CPUs  71 , one or more application specific integrated circuits (“ASICs”), or a combination of one or more CPUs  71  and one or more ASICs. 
     The disclosure may be applied to other devices, e.g., facsimile machines, copiers, and the life, in addition to printers. The inkjet head  2  may be configured to eject other liquid or fluid than ink. The recording medium may not be limited to the sheet P but may include any recording media for printing. 
     While the invention has been described in connection with embodiments of the invention, it will be understood by those skilled in the art that variations and modifications of the exemplary embodiments described above may be made without departing from the scope of the invention. Other embodiments will be apparent to those skilled in the art from a consideration of the specification or practice of the invention disclosed herein. It is intended that the specification and the described examples are considered merely as exemplary of the invention, with the true scope of the invention being defined by the following claims.