Patent Publication Number: US-2022227139-A1

Title: Liquid supply apparatus and image recording apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 17/071,371, filed Oct. 15, 2020, which is a continuation of U.S. patent application Ser. No. 16/556,933, filed Aug. 30, 2019, which claims priority from Japanese Patent Application No. 2018-163567 filed on Aug. 31, 2018, the contents of which are incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     Aspects of the disclosure relate to a liquid supply apparatus configured to store liquid therein and an image recording apparatus including the liquid supply apparatus. 
     BACKGROUND 
     A known printer includes a liquid supply apparatus. The liquid supply apparatus includes a cartridge to store ink therein, a sub tank connected to a recording head, and a liquid channel and an air channel to connect the cartridge and the sub tank. The cartridge is disposed above the sub tank. The liquid channel and the air channel connect the cartridge and the sub tank in a vertical direction. The liquid channel and the air channel are both open to the lower surface of the cartridge and the upper surface of the sub tank. 
     In the sub tank, the liquid channel extends downward further than the air channel, and the opening of the liquid channel is located above the opening of the air channel. At the cartridge replacement time, the sub tank is free of ink. When a new cartridge is connected to the sub tank, ink in the cartridge flows down into the sub tank via the liquid channel. Air in the sub tank with the same volume of ink having flowed is brought into the cartridge via the air channel. Such air/liquid replacement continues until the opening of the air channel is closed, and thus ink is stored in the sub tank. 
     During recording, as ink is ejected from the recording head, ink in the sub tank decreases and the ink level in the sub tank lowers away from the opening of the air channel. As the opening of the air channel is released, ink is supplied from the cartridge to the sub tank. The ink level in the sub tank rises with supply of ink and reaches the opening of the air channel. The opening of the air channel is closed and supply of ink from the cartridge is stopped. To compensate the consumption of ink at the recording head, ink is supplied from the cartridge to the sub tank, and thus the ink level in the sub tank is maintained at the level of the opening of the air channel. The sub tank remains mounted in the printer, and an empty cartridge is replaced with an ink-filled cartridge, so that the printer can be used continuously. 
     SUMMARY 
     In the above liquid supply apparatus, the cartridge is connected to the sub tank in a vertical direction, and thus needs attaching to the sub tank in the vertical direction, i.e., from above. Considering workability, the cartridge may be attached from the front of the printer more conveniently than from above. 
     In response to the above issue, one or more aspects of the disclosure provide a liquid supply apparatus with an improved workability of cartridge attachment. 
     One or more aspects of the disclosure provide a liquid supply apparatus with an increased space for storing liquid relative to a space occupied by a cartridge and a tank. 
     According to one or more aspects of the disclosure, a liquid supply apparatus includes a tank and a cartridge attachable to and detachable from the tank along an attachment and detachment direction crossing a vertical direction. The cartridge includes a casing, a first storing chamber, and a communication port. The casing has a front surface and a rear surface in the attachment and detachment direction. The casing further has a surface adjacent to the front surface. The first storing chamber is located between the front surface, the surface adjacent to the front surface, and the rear surface of the casing. The first storing chamber is configured to store liquid therein. The communication port is formed in one of the front surface and the surface adjacent to the front surface. The communication port is open in an attachment direction parallel to the attachment and detachment direction to allow the first storing chamber to communicate with an outside of the cartridge. The tank includes a second storing chamber configured to store liquid therein, a liquid channel communicating with the second storing chamber, an air channel communicating with the second storing chamber, and an air communication port allowing the second storing chamber to communicate with an outside of the tank. The liquid channel has a first opening, a second opening, and a first extension portion. The first opening is formed at one end of the liquid channel and communicating with the second storing chamber. The second opening is formed at the other end, opposite to the one end, of the liquid channel and open to an outside. The first extension portion extends from the second opening in the attachment direction. The air channel has a third opening, a fourth opening, and a second extension portion. The third opening is formed at one end of the air channel and communicating with the second storing chamber. The fourth opening is formed at the other end, opposite to the one end, of the air channel and open to an outside. The second extension portion extends from the fourth opening in the attachment direction. When the cartridge is attached to the tank with the first storing chamber of the cartridge communicating with the second opening and the fourth opening of the tank, the first storing chamber of the cartridge has a portion located above the liquid channel and the air channel of the tank. The second storing chamber of the tank has a first area located above a lower end of the first storing chamber of the cartridge in the vertical direction and a second area continuous with the first area and located below the first storing chamber of the cartridge in the vertical direction. The third opening is located in the second area. The first storing portion of the cartridge stores an initial volume of liquid having a first liquid surface. The second storing portion of the tank stores liquid having a second liquid surface at the same level with the third opening. When viewed in the vertical direction, the first liquid surface partially overlaps the second liquid surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a perspective view of a multifunction apparatus with a cover at its closed position according to aspects of the disclosure. 
         FIG. 1B  is a perspective view of the multifunction apparatus with the cover at its open position according to aspects of the disclosure. 
         FIG. 2  is a sectional view schematically illustrating an internal configuration of a printer of the multifunction apparatus according to aspects of the disclosure. 
         FIG. 3  is a plan view of a carriage and an ink supply apparatus according to aspects of the disclosure. 
         FIG. 4  is a perspective view of an ink cartridge according to aspects of the disclosure. 
         FIG. 5  is a sectional view of an ink cartridge and a sub tank, which are in an attached state, according to aspects of the disclosure. 
         FIG. 6  is a sectional view of an ink cartridge and a sub tank, which are in an attached state, according to aspects of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Aspects of the disclosure will be described with reference to the accompany drawings. While the disclosure will be described in detail with reference to particular examples, various changes, arrangements and modifications may be applied therein without departing from the spirit and scope of the disclosure. In the following description, an up-down direction  7  is defined in conjunction with an orientation in which a multifunction apparatus  10  is placed on a horizontal surface or an ink cartridge  50  is attached to the multifunction apparatus  10  (which is an orientation illustrated in  FIGS. 1A and 1B , and may refer to a use orientation). An attachment and detachment direction  8  is defined based on that a front surface of the multifunction apparatus  10  having an opening  13  is regarded as a surface facing rearward. A left-right direction  9  is defined when the multifunction apparatus  10  is viewed in an attachment direction  8 A. In the use orientation in the following description, the up-down direction  7  corresponds to a vertical direction, and the attachment and detachment direction  8  and the left-right direction  9  correspond to a horizontal direction. Regarding the attachment and detachment direction  8 , the same direction as the attachment direction  8 A is referred to as front, and a direction opposite to the attachment direction  8  is referred to as rear. 
     Embodiment 
     The following describes the multifunction apparatus  10  and an ink supply apparatus  15  according to an illustrative embodiment. 
     Structure of Multifunction Apparatus  10   
     As illustrated in  FIGS. 1A and 1B , the multifunction apparatus  10  (as an example of an image recording apparatus) is substantially box shaped. The multifunction apparatus  10  includes a printer  11 , a scanner  12 , and an operation panel  17 . The printer  11  is disposed in a lower portion of the multifunction apparatus  10  and is configured to record an image on a sheet  28  ( FIG. 2 ) using an inkjet recording method. The scanner  12  is a device with scan function and disposed above the printer  11 . The printer  11  includes a casing  14  with an opening  13 , and the ink supply apparatus  15 , which is located to the right of the opening  13  in the casing  14 . The operation panel  17  is located to the rear of the scanner  12  in the attachment and detachment direction  8 . The operation panel  17  has user selection keys to cause the multifunction apparatus  10  to execute functions regarding image recording by the printer  11  and image reading by the scanner  12 . 
     As illustrated in  FIG. 2 , the printer  11  includes, in the casing  14 , a feeder  16 , a sheet feed tray  20 , a sheet discharge tray  21 , a conveying roller pair  45 , a recording unit  24 , a discharge roller pair  46 , and a platen  42 . 
     Sheet Feed Tray  20  and Sheet Discharge Tray  21   
     As illustrated in  FIGS. 1A and 1B , the sheet feed tray  20  is insertable through the opening  13  into the casing  14 . The opening  13  is defined in a surface facing rearward in the attachment and detachment direction  8  and in a central portion thereof in the left-right direction  9 . As illustrated in  FIG. 2 , the sheet feed tray  20  is configured to support a stack of sheets  28 . The sheet discharge tray  21  is disposed above the sheet feed tray  20  and is removable in the attachment and detachment direction  8  together with the sheet feed tray  20 . The sheet discharge tray  21  supports a sheet  28  discharged by the discharge roller pair  46 . 
     Feeder  16   
     The feeder  16  is configured to feed a sheet  28  supported on the sheet feed tray  20  toward a conveyance path  38 . As illustrated in  FIG. 2 , the feeder  16  includes a feed roller  25 , an arm  26  and a shaft  27 . The feed roller  25  is rotatably supported at an end of the arm  26 . The feed roller  25  receives a driving force from a motor, not illustrated. The arm  26  is pivotally supported by the shaft  27  supported by a frame of the printer  11 . The arm  26  is urged by its own weight or an elastic force, for example, a spring, toward the sheet feed tray  20 . 
     In the following description, when the feed roller  25 , a conveying roller  34 , and a discharge roller  36  each rotate about a respective rotational axis to convey a sheet  28  in a conveyance direction  38 A, their rotation refers to forward rotation. 
     Conveyance Path  38   
     As illustrated in  FIG. 2 , the conveyance path  38  refers to a space partially defined in the printer  11  between an outer guide member  18  and an inner guide member  19  facing each other. The conveyance path  38  extends rearward from the sheet feed tray  20 . The conveyance path  38  is curved upward from the sheet feed tray  20  and then rearward in the attachment and detachment direction  8 , reaching the sheet discharge tray  21  via a space between the recording unit  24  and the platen  42 . As illustrated in  FIGS. 2 and 3 , a portion of the conveyance path  38  extending between the conveying roller pair  45  and the discharge roller pair  46  is located at a central portion of the multifunction apparatus  10  in the left-right direction  9 , and extends in the attachment and detachment direction  8 . The conveyance direction  38 A in the conveyance path  38  is indicated by an arrow in  FIG. 2 . 
     Conveyance Roller Pair  45   
     As illustrated in  FIG. 2 , the conveying roller pair  45  is disposed upstream from the recording unit  24  in the conveyance direction  38 A. The conveyor roller pair  45  includes a conveying roller  34  and a pinch roller  35 . The conveying roller  34  is configured to receive a driving force from a motor, not illustrated, and rotate in a forward or reverse direction. The pinch roller  35  is configured to rotate with the rotation of the conveying roller  34 . A sheet  28  is pinched between the conveying roller  34  rotating in the forward direction and the pinch roller  35 , and fed in the conveyance direction  38 A. 
     Discharge Roller Pair  46   
     As illustrated in  FIG. 2 , the discharge roller pair  46  is disposed downstream from the recording unit  24  in the conveyance direction  38 A. The discharge roller pair  46  includes a discharge roller  36  and a spur  37 . The discharge roller  36  is configured to receive a driving force from a motor, not illustrated, and rotate in the forward or reverse direction. The spur  37  is configured to rotate with the rotation of the discharge roller  36 . A sheet  28  is pinched between the discharge roller  36  rotating in the forward direction and the spur  37 , and fed in the conveyance direction  38 A. 
     Recording Unit  24   
     As illustrated in  FIG. 2 , the recording unit  24  is disposed between the conveying roller pair  45  and the discharge roller pair  46  in the conveyance direction  38 A. The recording unit  24  faces downwardly toward the platen  42  via the conveyance path  38  in the up-down direction  7 . The recording unit  24  includes the carriage  23  and a recording head  39  mounted on the carriage  23 . 
     As illustrated in  FIG. 3 , the carriage  23  is supported by guide rails  43 ,  44 , which are spaced apart from each other in the attachment and detachment direction  8  and each extend in the left-right direction  9 . The guide rails  43 ,  44  are supported by a frame, not illustrated. The carriage  23  is connected to a known belt mechanism disposed on the guide rail  44 . The belt mechanism includes a belt, which is configured to receive a driving force from a carriage-driving motor, not illustrated. The carriage  23  is guided by the guide rails  43 ,  44  along with the rotational movement of the belt, and reciprocates in the left-right direction  9 . The carriage  23  moves to the left and right, as indicated by a dot-and-dash line in  FIG. 3 , beyond a width  38 B of the conveyance path  38 . 
     The recording head  39  is connected to four sub tanks  100  ( FIG. 5 ) disposed in the ink supply apparatus  15  with four ink tubes  32 . The recording head  39  is connected to a control circuit board, not illustrated, via a flexible flat cable  33 . 
     The four sub tanks  100  includes a magenta sub tank  100 , a cyan sub tank  100 , a yellow sub tank  100 , and a black sub tank  100 . The magenta sub tank  100 , cyan sub tank  100 , yellow sub tank  100  and black sub tank  100  are collectively referred to as a sub tank  100  or sub tanks  100  unless otherwise specified in the following description. 
     The four ink tubes  32  includes a yellow ink tube  32 Y, a cyan ink tube  32 C, a magenta ink tube  32 M, and a black ink tube  32 B. The yellow ink tube  32 Y, cyan ink tube  32 C, magenta ink tube  32 M, and black ink tube  32 B are collectively referred to as an ink tube  32  or ink tubes  32  unless otherwise specified in the following description. The four ink tubes  32  are tied in a bundle. 
     The flexible flat cable  33  electrically connects the control circuit board having a controller mounted thereon and the recording head  39 . The flexible flat cable  33  transmits a control signal outputted from the controller to the recording head  39 . 
     As illustrated in  FIG. 2 , the recording head  39  has a lower surface formed with a plurality of nozzles  40 . The nozzles  40  are exposed from the lower surface of the recording head  39 . The recording head  39  ejects micro ink droplets from the nozzles  40 . While the carriage  23  moves, the recording head  39  ejects ink droplets toward a sheet  28  supported by the platen  42 . Thus, an image is recorded on the sheet  28 . Ink stored in the four sub tanks  100  is consumed accordingly. 
     Platen  42   
     As illustrated in  FIGS. 2 and 3 , the platen  42  is disposed between the conveying roller pair  45  and the discharge roller pair  46  in the conveyance path  38 . The platen  42  is disposed below and faces upwardly toward the recording unit  24  via the conveyance path  38  in the up-down direction  7 . The platen  42  supports a sheet  28 , which is conveyed by the conveying roller pair  45 , from below. 
     Cover  48   
     As illustrated in  FIG. 1B , the casing  14  has an opening  47  at a right portion of a surface facing rearward in the attachment and detachment direction  8 . The casing  14  accommodates the ink supply apparatus  15 , and ink cartridges  50  are illustrated as being exposed from the opening  47  at their rear walls  58 . The casing  14  includes a cover  48  to open and close the opening  47 . The cover  48  has its lower end supported below the opening  47  by the casing  14  such that the cover  48  is pivotable about a shaft extending in the left-right direction. The cover  48  is pivotable between a closed position ( FIG. 1A ) to close the opening  47  and an open position ( FIG. 1B ) to open the opening  47 . 
     As illustrated in  FIG. 1A , the cover  48  has a light-transmissive window  49 . The light-transmissive window  49  is transparent to light to see inside from outside of the cover  48 . When the cover  48  is at the closed position, the rear walls  58  of the ink cartridges  50  attached to the ink supply apparatus  15  are visible through the light-transmissive window  49 . 
     Ink Supply Apparatus  15   
     As illustrated in  FIG. 3 , the ink supply apparatus  15  (as an example of a liquid supply apparatus) includes four ink cartridges  50  and four sub tanks  100  ( FIG. 5 ). 
     Ink Cartridge  50   
     As illustrated in  FIGS. 1A, 1B, and 3 , four ink cartridges  50  (each as an example of a cartridge) include a magenta ink cartridge  50 M, a cyan ink cartridge  50 C, a yellow ink cartridge  50 Y, and a black ink cartridge  50 B. The magenta ink cartridge  50 M, cyan ink cartridge  50 C, yellow ink cartridge  50 Y, and black ink cartridge  50 B are collectively referred to as an ink cartridge  50  or ink cartridges  50  unless otherwise specified in the following description. 
     As illustrated in  FIGS. 4 and 5 , an ink cartridge  50  includes a cartridge casing  51 . The cartridge casing  51  has a first storing chamber  53  for storing ink (as an example of liquid), and communication ports  62 ,  63 . 
     The cartridge casing  51  is substantially box-shaped. The cartridge casing  51  is of a rectangle when viewed in the up-down direction  7  and when viewed in the attachment and detachment direction  8 . The cartridge casing  51  has an upper wall  54 , a right wall  57 , a left wall  56 , a rear wall  58 , a front wall  59 , and a lower wall  60 . The upper wall  54  has an outer surface corresponding to an upper surface and the rear wall  58  has an outer surface corresponding to and a rear surface. The cartridge casing  51  has a front face facing in the attachment direction  8 A. The first storing chamber  53  is located between the front wall  59  and the rear wall  58 . 
     The cartridge casing  51  has the communication ports  62 ,  63  in the front wall  59 . The communication ports  62 ,  63  are open in the attachment direction  8 A. The communication port  62  is below the communication port  63 . The communication ports  62 ,  63  allow the first storing chamber  53  to communicate with an outside of the ink cartridge  50 . Although not illustrated, the communication ports  62 ,  63  are openable to the outside by known valves. 
     Sub Tank  100   
     As illustrated in  FIG. 5 , a sub tank  100  (as an example of a tank) includes a tank body  101  and joints  120 ,  121 . The tank body  101  includes, inside, a second storing chamber  105  configured to store ink therein. The joints  120 ,  121  are shaped like a tube, and extend from the rear wall of the tank body  101  rearward in the attachment direction  8 A or in a direction opposite to the attachment direction  8 A. Each of the joints  120 ,  121  has an internal space communicating with the second storing chamber  105  via a respective through hole in the rear wall of the tank body  101 . The joint  120  is below the joint  121 . 
     The sub tank  100  includes a liquid channel  103  and an air channel  104 , which communicate with the second storing chamber  105 . The liquid channel  103  is defined inside the tank body  101  and the joint  120 . The air channel  104  is defined inside the tank body  101  and the joint  121 . The sub tank  100  includes an air communication port  106 , which allows the second storing chamber  105  to communicate with an outside of the sub tank  100 . 
     Liquid Channel  103  and Air channel  104   
     The liquid channel  103  has a first opening  131 , a second opening  132 , a vertical portion  133 , and an extension portion  134 . The first opening  131  is formed at one end of the liquid channel  103  and communicates with the second storing chamber  105 . The first opening  131  is open downward in the up-down direction  7 . The second opening  132  is formed at the other end of the liquid channel  103  and is open to an outside of the sub tank  100 . The second opening  132  is open toward the rear along the attachment and detachment direction  8 . The second opening  132  is located inside the first storing chamber  53  of the ink cartridge  50  attached to the sub tank  100 . The vertical portion  133  defines a portion of the liquid channel  103 , extending upward from the first opening  131 . The extension portion  134  (as an example of a first extension portion) defines a portion of the liquid channel  103 , extending from the second opening  132  in the attachment direction  8 A. The vertical portion  133  has its upper end connected to the front end of the extension portion  134 . 
     The air channel  104  has a third opening  141 , a fourth opening  142 , a vertical portion  143 , and an extension portion  144 . The third opening  141  is formed at one end of the air channel  104  and communicates with the second storing chamber  105 . The third opening  141  is open downward in the up-down direction  7 . The fourth opening  142  is formed at the other end of the air channel  104  and is open to an outside of the sub tank  100 . The fourth opening  142  is open toward the rear along the attachment and detachment direction  8 . The fourth opening  142  communicates with the first storing chamber  53  of the ink cartridge  50  attached to the sub tank  100 . The vertical portion  143  defines a portion of the air channel  104 , extending upward from the third opening  141 . The extension portion  144  (as an example of a second extension portion) defines a portion of the air channel  104 , extending from the fourth opening  142  in the attachment direction  8 A. The vertical portion  143  has its upper end connected to the front end of the extension portion  144 . 
     Tank Body  101   
     The tank body  101  is box-shaped and has an upper portion  101 A and a lower portion  101 B. The upper portion  101 A is on top of a front portion of the lower portion  101 B in the attachment direction  8 A. The upper portion  101 A has an internal space  102 A (as an example of a first area). When the ink cartridge  50  is attached to the sub tank  100 , the internal space  102 A is above a lower end  53 B of the first storing chamber  53 . The lower portion  101 B has an internal space  102 B (as an example of a second area). When the ink cartridge  50  is attached to the sub tank  100 , the internal space  102 B is below the lower end  53 B of the first storing chamber  53 . The internal space  102 A of the upper portion  101 A and the internal space  102 B of the lower portion  101 B are continuous with each other, forming the second storing chamber  105 . The internal space  102 A has a volume Va greater than a volume Vb of the internal space  102 B (Va&lt;Vb). 
     The lower portion  101 B of the sub tank  100  has a lower wall formed with a communication port  129 , which communicates with the second storing chamber  105 . The communication port  129  receives one end of the ink tube  32 , which allows the second storing chamber  105  to communicate with the recording head  39 . 
     The upper portion  101 A of the tank body  101  has a front wall formed with the air communication port  106  passing therethrough near its upper end. The second storing chamber  105  communicates with an outside of the sub tank  100  via the air communication port  106 . 
     The tank body  101  has, in its internal space, partition walls and tubes, which define a portion of the liquid channel  103  including the vertical portion  133 . The liquid channel  103  has the first opening  131  in the internal space  102 B of the lower portion  101 B. The tank body  101  has, in its internal space, partition walls and tubes, which define a portion of the air channel  104  including the vertical portion  143 . The third opening  141  of the air channel  104  is in the internal space  102 B of the lower portion  101 B. The third opening  141  of the air channel  104  is located above the first opening  131  of the liquid channel  103 . 
     Attached State of Ink Cartridge  50   
     As illustrated in  FIG. 5 , the ink cartridge  50  is attached to the sub tank  100  with the joint  120  of the sub tank  100  inserted into the communication port  62  of the ink cartridge  50  along the attachment and detachment direction  8 . The joint  121  of the sub tank  100  is inserted into the communication port  63  of the ink cartridge  50  along the attachment and detachment direction  8 . In the attached state, the second opening  132  of the liquid channel  103  of the sub tank  100  is located in the first storing chamber  53  of the ink cartridge  50 . The fourth opening  142  of the air channel  104  of the sub tank  100  is located in the first storing chamber  53  of the ink cartridge  50 . The ink cartridge  50  is attachable to and detachable from the sub tank  100  along the attachment and detachment direction  8 . 
     Layout of Ink Cartridge  50  and Sub Tank  100   
     The following describes a layout of the ink cartridge  50  and the sub tank  100  based on that the ink cartridge  50  and the sub tank  100  which are at the use orientation illustrated in  FIG. 5 . 
     As illustrated in  FIG. 5 , the upper portion  101 A of the tank body  101  faces the front wall  59  of the ink cartridge  50  in the attachment and detachment direction  8 . The lower portion  101 B of the tank body  101  is located below the lower wall  60  of the ink cartridge  50  in the up-down direction  7 . 
     Most part of the first storing chamber  53  is located above the extension portion  134  of the liquid channel  103  and the extension portion  144  of the air channel  104 . The lower portion of the first storing chamber  53  and the internal space  102 A of the upper portion  101 A of the tank body  101  are aligned in the attachment and detachment direction  8 . The first storing chamber  53  has a greater capacity than the second storing chamber  105  has. 
     The internal space  102 A of the upper portion  101 A of the tank body  101  is located at a position overlapping, in the up-down direction  7 , a portion of the extension portion  134  of the liquid channel  103  and a portion of the extension portion  144  of the air channel  104 . The internal space  102 B of the lower portion  101 B of the tank body  101  is located below the extension portion  134  of the liquid channel  103  and the extension portion  144  of the air channel  104  in the up-down direction  7 . 
     The extension portion  144  of the air channel  104  is located above the extension portion  134  of the liquid channel  103 . 
     As illustrated in  FIG. 5 , the first storing chamber  53  stores an initial volume of ink having a liquid surface L 1  (as an example of a first liquid surface), and the second storing chamber  105  stores ink having a liquid surface L 2  (as an example of a second liquid surface) at the same level with the third opening  141  of the air channel  104 . When viewed in the up-down direction  7 , the liquid surface L 1  partially overlaps the liquid surface L 2 . In  FIG. 5 , a range R 1  in the attachment and detachment direction  8  indicates an overlap between the liquid surface L 1  and the liquid surface L 2 . 
     Flows of Ink and Air 
     The following describes flows of ink and air between the ink cartridge  50  and the sub tank  100  in an initial-ink-supply operation when the ink cartridge  50  is attached to the empty sub tank  100  for the first time. 
     Before the initial-ink-supply operation, the ink cartridge  50  is not attached to the sub tank  100 . At this time, the first storing chamber  53  stores an initial volume of ink whose surface is the liquid surface L 1 . The second storing chamber  105  stores no ink or is empty. 
     As illustrated in  FIG. 5 , when the ink cartridge  50  is attached to the sub tank  100  in the attachment direction  8 A, the communication port  62  of the ink cartridge  50  receives the joint  120  of the sub tank  100 , and the communication port  63  of the ink cartridge  50  receives the joint  121  of the sub tank  100 . The lower portion of the first storing chamber  53  thus communicates with the second storing chamber  105  via the liquid channel  103 . The lower portion of the first storing chamber  53  communicates with the second storing chamber  105  via the air channel  104 . This allows ink in the first storing chamber  53  of the ink cartridge  50  to naturally flow down into the second storing chamber  105  via the liquid channel  103 . Air with the same volume of ink having flowed into the second storing chamber  105  flows into the first storing chamber  53  via the air channel  104 . Thus, ink in the first storing chamber  53  is replaced with air (air/liquid replacement), and supplied to the second storing chamber  105 . 
     The ink level in the second storing chamber  105  rises as the ink in the first storing chamber  53  flows into the second storing chamber  105 . The ink level rises until the ink closes the third opening  141  of the air channel  104 . While the ink closes the third opening  141 , the ink in the first storing chamber  53  does not flow into the second storing chamber  105 . At this time, the second storing chamber  105  stores ink whose surface is the liquid surface L 2 . This is how the ink is supplied in the initial-ink-supply operation. While ink is left between ink detection plates  158 , electric current flows between the ink detection plates  158 . Thus, detecting the electric current flow may indicate that the ink level in the second storing chamber  105  has risen to a predetermined level. 
     The following describes flows of ink and air between the ink cartridge  50  and the sub tank  100  when the printer  11  performs recording while the ink cartridge  50  is attached to the sub tank  100 . 
     During recording, as ink is ejected from the recording head  39 , ink in the second storing chamber  105  is drawn through the communication port  129  to the recording head  39 . As ink in the second storing chamber  105  decreases, the ink level lowers away from the third opening  141  of the air channel  104 , air corresponding to a volume of the decreased ink is drawn through the air communication port  106  to the second storing chamber  105 , and the third opening  141  of the air channel  104  is released. Then, ink to compensate the decreased ink is supplied from the first storing chamber  53  to the second storing chamber  105  as the same volume of air flows out from the second storing chamber  105  through the third opening  141 . Thus, the liquid surface L 2  in the second storing chamber  105  is maintained at the level of the third opening  141  of the air channel  104 . In this manner, the air/liquid replacement continuously occurs. 
     After the ink level in the first storing chamber  53  becomes lower below the second opening  132 , the ink level in the second storing chamber  105  gradually lowers every time ink is ejected from the recording head  39 , and the third opening  141  of the air channel  104 , which has been closed by ink, is released. When the ink level in the second storing chamber  105  further lowers until no ink is left between the ink detection plates  158 , no or lower electric current flows between the ink detection plates  158 . Thus, detecting no or lower electric current flow may indicate that the ink level in the second storing chamber  105  has lowered to a predetermined level so that the multifunction apparatus  10  outputs information that the first storing chamber  53  of the ink cartridge  50  becomes “empty” though a little ink remains below the second opening  132  in the first storing chamber  53 . The “empty” ink cartridge  50  is replaced with a new one filled with ink, and the multifunction apparatus  10  can thus performs recording operation thereafter. 
     Effects 
     The first storing chamber  53  and the second storing chamber  105  are connected to each other via the liquid channel  103  and the air channel  104 , and ink in the first storing chamber  53  can be supplied to the second storing chamber  105  by the air/liquid replacement. The ink cartridge  50  can be attached to the sub tank  100  along the attachment and detachment direction  8  crossing the vertical direction. This provides improved workability for attachment and detachment of the ink cartridge  50 . The communication ports  62 ,  63  are formed in the front wall  59  of the cartridge casing  51 , and thus the lower wall  60  of the cartridge casing  51  can be entirely used as a surface to be placed on to stabilize the position of the cartridge casing  51 . When the ink cartridge  50  is attached to the sub tank  100 , the liquid surface L 1  and the liquid surface L 2  partially overlap each other when viewed in the up-down direction  7 . This overlap provides increased volumes of the first storing chamber  53  and the second storing chamber  105  relative to the respective spaces occupied by the ink cartridge  50  and the sub tank  100 . 
     In the sub tank  100 , the volume Va of the internal space  102 A of the upper portion  101 A is smaller than the volume Vb of the internal space  102 B of the lower portion  101 B. This provides a decreased dimension of the second storing chamber  105  in the attachment and detachment direction  8 . The volume Vb is greater than the volume Va. In the attached state, the second storing chamber  105  located below the first storing chamber  53  can be thus used as a space where ink can be stored. 
     Alternative Embodiment 
     The ink supply apparatus  15  is attached and detached horizontally in the attachment and detachment direction  8 . The attachment and detachment direction  8  may be a direction crossing the horizontal direction and the vertical direction. In an example illustrated in  FIG. 6 , the attachment and detachment direction  8  is a direction crossing the vertical direction and the horizontal direction, and the attachment direction  8 A is directed diagonally downward. 
     In this example, the cartridge casing  51  of the ink cartridge  50  has an inclined wall  55  continuous with the front wall  59  and the lower wall  60 . The inclined wall  55  faces diagonally downward in the attachment direction  8 A. The inclined wall  55  may has an outer surface (an example of a surface adjacent to the front surface) continuous with an outer surface (front surface) of the front wall  59 . 
     The tank body  101  has an inclined wall  107  to face the inclined wall  55  when the ink cartridge  50  is attached to the sub tank  100 . Joints  120 ,  121  protrude from the inclined wall  107  along the attachment and detachment direction  8 . The extension portions  134 ,  144 , which are defined by respective internal spaces of the joints  120 ,  121 , extend in the attachment and detachment direction  8 , which crosses the horizontal direction. The extension portion  144  is located above the extension portion  134  relative to a position in the attachment and detachment direction  8  (or a position on an imaginary line parallel to the attachment and detachment direction  8 ). 
     In the above-described configurations in  FIGS. 5 and 6 , the joint  120  defining the liquid channel  103  and the joint  121  defining the air channel  104  are provided as independent tubes. According to one or more aspects, a single tube may define a single joint having separate compartments within it such that one compartment defines the liquid channel  103  and the other one compartment defines the air channel  104 . 
     In the above ink supply apparatus  15 , the liquid channel  103  has the vertical portion  133  and the extension portion  134 , and the air channel  104  has the vertical portion  143  and the extension portion  144 . According to one or more aspects, the liquid channel  103  may have the extension portion  134  only, that is, may not have the vertical portion  133 . Similarly, the air channel  104  may have the extension portion  144  only, that is, may not have the vertical portion  143 . The extension portion  134  of the liquid channel  103  may be located above the extension portion  144  of the air channel  104 . 
     In the above-described configuration in  FIG. 5 , the first storing chamber  53  has a greater capacity than the second storing chamber  105 . The first storing chamber  53  may be identical in capacity to the second storing chamber  105  or have a smaller capacity than the second storing chamber  105 .