Patent Publication Number: US-2023145170-A1

Title: Control device setting order condition for ordering cartridge to be mounted in recording device provided with tank

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 17/098,583, filed, Nov. 16, 2020, which is a continuation of U.S. patent application Ser. No. 16/229,570, filed, Dec. 21, 2018, now U.S. Pat. No. 10,836,177, which claims priority from Japanese Patent Application No. 2017-252676 filed Dec. 27, 2017. The contents of the aforementioned applications are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND ART 
     Technical Field 
     The present disclosure relates to a control device and a program for ordering cartridges accommodating a printing agent. 
     Background 
     Some conventional printers known in the art are capable of placing orders for cartridges that accommodate a developing agent. The printer uses the residual quantity of the developing agent in the cartridge to estimate the day on which printing using the current cartridge will become impossible and sets a signal transmission date for transmitting an order request signal on the basis of the estimated day on which printing will become impossible. The printer sends an order request signal when the current date matches the signal transmission date. 
     DESCRIPTION 
     Summary 
     In order to avoid cases in which the printer becomes unable to print while waiting for a cartridge to be delivered, the printer according to the conventional technology described above ensures that the ordered cartridge will arrive while the cartridge currently mounted in the printer still contains the developing agent. Since it is likely the cartridge will be delivered before the current cartridge mounted in the printer becomes empty, the developing agent in the current cartridge may be wasted when the cartridge is replaced. 
     In view of the foregoing, it is an object of the present disclosure to provide means for preventing cases in which a printer becomes unable to print while waiting for a new cartridge to arrive and for preventing printing agent from being wasted when a cartridge that still contains printing agent is replaced by a new cartridge. 
     In order to attain the above and other objects, the present disclosure provides a control device including a controller. The controller is configured to perform (a) acquiring an index value from a recording device at an acquisition timing. The recording device includes: a mounting case; a tank; and a recording portion. A cartridge accommodating a printing agent is mountable in the mounting case. The tank is configured to accommodate the printing agent supplied from the cartridge. The recording portion is configured to record an image on a sheet with the printing agent supplied from the tank. The index value is acquired under a condition where a first cartridge is mounted in the mounting case of the recording device. The index value is representative of a residual quantity of the printing agent remaining in the first cartridge and the tank at the acquisition timing. The controller is configured to further perform: (b) storing the index value in association with timing information about the acquisition timing in a memory; and (c) setting, after performing the (a) acquiring and the (b) storing a plurality of number of times and storing a plurality of index values in the memory in association with a plurality of sets of timing information, an order condition using the plurality of sets of timing information and the plurality of index values stored in the memory. The plurality of index values includes a latest index value acquired at a latest acquisition timing. The order condition requires that one of the latest index value and a current timing have reached corresponding one of a reference index value and a reference timing. The order condition is set so that a second cartridge ordered for replacement with the first cartridge is delivered to a predetermined destination at a first timing by assuming that a time interval between the reference timing and the first timing is a first period of time. The first timing is a timing at which the first cartridge is expected to be out of the printing agent while the tank is expected to still accommodate the printing agent. The first period of time is an expected period of time after the second cartridge has been ordered and delivered to the predetermined destination. The controller is configured to further perform (d) transmitting an order command to a relevant device after the order condition is satisfied. The order command instructs to order the second cartridge. 
     According to another aspect, the present disclosure provides a non-transitory computer readable storage medium storing a set of program instructions. The set of program instructions is installed on and executed by a computer. The set of program instructions includes (a) acquiring an index value from a recording device at an acquisition timing. The recording device includes: a mounting case; a tank; and a recording portion. A cartridge accommodating a printing agent is mountable in the mounting case. The tank is configured to accommodate the printing agent supplied from the cartridge. The recording portion is configured to record an image on a sheet with the printing agent supplied from the tank. The index value is acquired under a condition where a first cartridge is mounted in the mounting case of the recording device. The index value is representative of a residual quantity of the printing agent remaining in the first cartridge and the tank at the acquisition timing. The set of program instructions further includes: (b) storing the index value in association with timing information about the acquisition timing in a memory; and (c) setting, after performing the (a) acquiring and the (b) storing a plurality of number of times and storing a plurality of index values in the memory in association with a plurality of sets of timing information, an order condition using the plurality of sets of timing information and the plurality of index values stored in the memory. The plurality of index values includes a latest index value acquired at a latest acquisition timing. The order condition requires that one of the latest index value and a current timing have reached corresponding one of a reference index value and a reference timing. The order condition is set so that a second cartridge ordered for replacement with the first cartridge is delivered to a predetermined destination at a first timing by assuming that a time interval between the reference timing and the first timing is a first period of time (delivery lead time), the first timing being a timing at which the first cartridge is expected to be out of the printing agent while the tank is expected to still accommodate the printing agent. The first period of time is an expected period of time after the second cartridge has been ordered and delivered to the predetermined destination. The set of program instructions further includes (d) transmitting an order command to a relevant device after the order condition is satisfied. The order command instructs to order the second cartridge. 
     According to still another aspect, the present disclosure provides a method executed by a computer for placing an order for a cartridge to be mounted in a recording device. The recording device includes: a mounting case; a tank; and a recording portion. The cartridge accommodating a printing agent is mountable in the mounting case. The tank is configured to accommodate the printing agent supplied from the cartridge. The recording portion is configured to record an image on a sheet with the printing agent supplied from the tank. The method includes (a) acquiring an index value from the recording device at an acquisition timing. The index value is acquired under a condition where a first cartridge is mounted in the mounting case of the recording device. The index value is representative of a residual quantity of the printing agent remaining in the first cartridge and the tank at the acquisition timing. The method further includes: (b) storing the index value in association with timing information about the acquisition timing in a memory; and (c) setting, after performing the (a) acquiring and the (b) storing a plurality of number of times and storing a plurality of index values in the memory in association with a plurality of sets of timing information, an order condition using the plurality of sets of timing information and the plurality of index values stored in the memory. The plurality of index values includes a latest index value acquired at a latest acquisition timing. The order condition requires that one of the latest index value and a current timing have reached corresponding one of a reference index value and a reference timing. The order condition is set so that a second cartridge ordered for replacement with the first cartridge is delivered to a predetermined destination at a first timing by assuming that a time interval between the reference timing and the first timing is a first period of time (delivery lead time), the first timing being a timing at which the first cartridge is expected to be out of the printing agent while the tank is expected to still accommodate the printing agent. The first period of time is an expected period of time after the second cartridge has been ordered and delivered to the predetermined destination. The method further includes (d) transmitting an order command to a relevant device after the order condition is satisfied. The order command instructs to order the second cartridge. 
    
    
     
       DESCRIPTION 
       Brief Description of the Drawings 
       The particular features and advantages of the disclosure as well as other objects will become apparent from the following description taken in connection with the accompanying drawings, in which: 
         FIG.  1    is a block diagram illustrating an ordering system provided with a printer and an information collection server according to embodiments of the present disclosure; 
         FIG.  2 A  is a perspective view of the printer according to the embodiments, and illustrating a closed position of a cover; 
         FIG.  2 B  is a perspective view of the printer according to the embodiments, and illustrating an open position of the cover; 
         FIG.  3    is a vertical cross-sectional view schematically illustrating an internal configuration of the printer according to the embodiments; 
         FIG.  4    is a vertical cross-sectional view illustrating a mounting case of the printer according to the embodiments; 
         FIG.  5 A  is a perspective view of a cartridge as viewed from a rear side of the cartridge in the printer according to the embodiments; 
         FIG.  5 B  is a vertical cross-sectional view of the cartridge in the printer according to the embodiments; 
         FIG.  6    is a vertical cross-sectional view of the mounting case in which the cartridge is mounted in the printer according to the embodiments; 
         FIG.  7    is a flowchart illustrating steps in a printing process executed by a controller of the printer according to the embodiments; 
         FIG.  8 A  is a flowchart illustrating steps in a first updating process executed by the controller of the printer according to the embodiments, the first updating process being executed under a condition where a cartridge is mounted in the mounting case of the printer while a value of a S_Empty Flag is set to “ON”; 
         FIG.  8 B  is a flowchart illustrating steps in a second updating process executed by the controller of the printer according to the embodiments, the second updating process being executed under a condition where liquid level signals acquired in S 15  and S 17  of  FIG.  7    are both “L”; 
         FIG.  8 C  is a flowchart illustrating steps in a third updating process executed by the controller of the printer according to the embodiments the third updating process being executed under a condition where the liquid level signal acquired in S 15  of  FIG.  7    is “L” but the liquid level signal acquired in S 17  of  FIG.  7    is “H”; 
         FIG.  8 D  is a flowchart illustrating steps in a fourth updating process executed by the controller of the printer according to the embodiments, the fourth updating process being executed under a condition where the liquid level signals acquired in S 15  and S 17  of  FIG.  7    are both “H”; 
         FIG.  9 A  is a flowchart illustrating a part of steps in a management information transmission process executed by the controller of the printer according to the embodiment; 
         FIG.  9 B  is a flowchart illustrating a remaining part of steps in the management information transmission process executed by the controller of the printer according to the embodiments; 
         FIG.  10    is a flowchart illustrating an ordering process executed by a controller of the information collection server according to the embodiments; 
         FIG.  11 A  is a flowchart illustrating an order date/time setting process executed by the controller of the information collection server according to the embodiments; 
         FIG.  11 B  is a flowchart illustrating an order date/time modification process executed by the controller of the information collection server according to a second embodiment; 
         FIG.  11 C  is a flowchart illustrating an order date/time modification process executed by the controller of the information collection server according to a third embodiment; 
         FIG.  12 A  illustrates a graph representing a linear function, an estimated arrival date/time, and an order date/time in a first embodiment; 
         FIG.  12 B  illustrates a graph representing a linear function, an estimated arrival date/time, and an order date/time in a first modification; 
         FIG.  13 A  is an explanatory diagram illustrating an example of a residual quantity management list stored in a storage unit of the information collection server according to the embodiments; 
         FIG.  13 B  is an explanatory diagram illustrating an example of a cartridge management list stored in the storage unit of the information collection server according to the embodiments; 
         FIG.  14 A  illustrates a graph representing a linear function, an estimated arrival date/time, and an order date/time in the second embodiment; 
         FIG.  14 B  illustrates a graph representing a linear function, an estimated arrival date/time, and an order date/time in the third embodiment; 
         FIG.  15 A  illustrates a graph representing a linear function, an estimated arrival date/time, and an order date/time in a second modification; 
         FIG.  15 B  illustrates a graph representing a linear function, an estimated arrival date/time, and an order date/time in a third modification; 
         FIG.  16 A  is a flowchart illustrating a part of steps in a management information transmission process executed by a controller of a printer according to a fourth modification; 
         FIG.  16 B  is a flowchart illustrating a remaining part of steps in the management information transmission process executed by the controller of the printer according to the fourth modification; 
         FIG.  17 A  is a flowchart illustrating a part of steps in a management information transmission process executed by a controller of a printer according to a fifth modification; 
         FIG.  17 B  is a flowchart illustrating a remaining part of steps in the management information transmission process executed by the controller of the printer according to the fifth modification; 
         FIG.  18 A  is a flowchart illustrating an order date/time setting process executed by the controller of the information collection server according to the fourth modification; 
         FIG.  18 B  is a flowchart illustrating an order date/time setting process executed by the controller of the information collection server according to the fifth modification; 
         FIG.  19 A  illustrates a graph representing a linear function, an estimated arrival date/time, and an order date/time in the fourth modification; 
         FIG.  19 B  illustrates a graph representing a linear function, an estimated arrival date/time, and an order date/time in the fifth modification; 
         FIG.  20 A  is a flowchart illustrating an order condition setting process executed by a controller of an information collection server according to a sixth modification; and 
         FIG.  20 B  illustrates a graph representing a linear function and an order residual percentage in the sixth modification. 
     
    
    
     DETAILED DESCRIPTION 
     Next, embodiments of the present disclosure will be described while referring to the accompanying drawings. Note that the embodiments described below are merely examples of the disclosure and may be modified in many ways without departing from the spirit of the disclosure, the scope of which is defined by the attached claims. Further, the order in which each of the processes described below are executed may be modified as desired without departing from the spirit of the disclosure. 
       FIG.  1    illustrates an ordering system  5 . The ordering system  5  is provided with one or a plurality of printers  10 , and an information collection server  40  that collects information from the one or plurality of printers  10 . The printer  10  and information collection server  40  are connected to each other through a communication circuit  6 , such as the Internet. The printer  10  and information collection server  40  can communicate with each other using a communication protocol, such as Transmission Control Protocol/Internet Protocol (TCP/IP). The information collection server  40  can also transmit information via the communication circuit  6  to a shipping server  50  that receives orders. The information collection server  40  is an example of the control device and the computer of the present disclosure. The printer  10  is an example of the image recording apparatus of the present disclosure. 
     &lt;Overview of the Printer  10 &gt; 
     The printer  10  illustrated in  FIGS.  2 A and  2 B  is an inkjet printer that records images on sheets by ejecting ink droplets. The printer  10  may be a multifunction peripheral possessing various functions, such as a facsimile function, a scan function, and a copy function, and the like. 
     In the following description, front, rear, left, and right directions related to the printer  10  will be referred to as assuming that the printer  10  is disposed on a horizontal plane so as to be operable, as illustrated in  FIG.  2 A . Note that this posture of the printer  10  illustrated in  FIG.  2 A  will be referred to as an “operable posture”. Specifically, an up-down direction  7  of the printer  10  is defined on the basis of the operable posture of the printer  10 . A front-rear direction  8  is defined such that a surface of the printer  10  in which an opening  13  is formed constitutes a front surface. A left-right direction  9  is defined on the basis of an assumption that the printer  10  in the operable posture is viewed from its front surface. In other words, in the operable posture of the printer  10 , the up-down direction  7  corresponds to a vertical direction, and the front-rear direction  8  and left-right direction  9  correspond to horizontal directions. The front-rear direction  8  and left-right direction  9  are orthogonal to each other. 
     As illustrated in  FIGS.  2 A and  2 B , the printer  10  is configured with a box-like housing  14 . The opening  13  is formed in a front surface  14 A of the housing  14  and is recessed inward into the housing  14 . A feed tray  15  is disposed inside the housing  14  in the bottom of the opening  13 . The feed tray  15  supports a plurality of sheets in a stacked state. A discharge tray  16  is provided above the feed tray  15 . The discharge tray  16  supports sheets that have undergone image recording. 
     As illustrated in  FIG.  3   , a feed roller  23 , a pair of conveying rollers  25 , a recording head  21 , and a pair of discharge rollers  27  are disposed inside the housing  14 . The printer  10  also includes ink tanks  160  that supply ink to the recording head  21  through tubes  19 . The printer  10  drives the feed roller  23  and conveying rollers  25  to convey sheets from the feed tray  15  to a position over a platen  26  that opposes the recording head  21 . Next, the printer  10  controls the recording head  21  to eject ink through nozzles  29 . The ink impacts the sheet supported on the platen  26  to record images on the sheet. Subsequently, the printer  10  drives the discharge rollers  27  to discharge the recorded sheet onto the discharge tray  16 . The ink is an example of the printing agent of the present disclosure. The head  21  is an example of the recording portion of the present disclosure. 
     More specifically, the recording head  21  is supported in a carriage  20 . The carriage  20  reciprocates along a main scanning direction (parallel to the left-right direction  9 ) that intersects the direction that the conveying rollers  25  convey the sheets. A motor (not illustrated) transmits a drive force to the carriage  20  for moving the carriage  20  in the main scanning direction (a direction perpendicular to the surface of the drawing in  FIG.  3   ). While the conveying rollers  25  has halted conveyance of the sheet, the printer  10  moves the carriage  20  in the main scanning direction and controls the recording head  21  to eject ink through the nozzles  29 , thereby recording an image in a region constituting the portion of the sheet opposing the recording head  21  (hereinafter also referred to as “one pass”). Next, the printer  10  controls the conveying rollers  25  to convey the sheet so that the next region to be recorded opposes the recording head  21 . By repeatedly and alternatingly performing these processes of recording and conveying, the printer  10  records an image on one sheet. 
     &lt;Display  28 &gt; 
     As illustrated in  FIGS.  2 A and  2 B , the housing  14  also has a display  28  and an operating panel  22  disposed on the front surface  14 A of the housing  14 . However, a touchscreen configured of touch sensors arranged over a display panel, or a display panel and push buttons along with or in place of the display  28  may be provided on the front surface  14 A of the housing  14  in place of the display  28  and operating panel  22 . The operating panel  22  receives input from the user. 
     &lt;Cover  87 &gt; 
     As illustrated in  FIG.  2 B , an opening  85  is formed in the front surface  14 A of the housing  14  at the right end thereof. The housing  14  is also provided with a cover  87 . The cover  87  is supported on the housing  14  near the bottom edge of the same and can pivot about a pivot axis extending in the left-right direction  9 . The cover  87  is pivotable between a closed position (the position illustrated in  FIG.  2 A ) for covering the opening  95 , and an open position (the position illustrated in  FIG.  2 B ) for exposing the opening  85 . An accommodating space  86  is formed in the housing  14 , expanding into the housing  14  from the opening  85 . A mounting case  150  is positioned in the accommodating space  86 . Cartridges  200  are detachably mounted in the mounting case  150 . 
     &lt;Mounting Case  150 &gt; 
     As illustrated in  FIG.  4   , the mounting case  150  is provided with contacts  152 , rods  153 , mounting sensors  32 , liquid level sensors  33 , and a locking pin  156 . The mounting case  150  can accommodate four of the cartridges  200  for the corresponding colors black, cyan, magenta, and yellow. In other words, the mounting case  150  is provided with four each of the contacts  152 , rods  153 , mounting sensors  32 , and liquid level sensors  33  to correspond to the four cartridges  200 . Note that the number of cartridges  200  that can be accommodated in the mounting case  150  is not limited to four, but may be one, or five or more. 
     The mounting case  150  has a box shape with an interior space for accommodating the cartridges  200 . The interior space of the mounting case  150  is defined by a top wall enclosing the top side of the interior space, a bottom wall enclosing the bottom side of the interior space, a rear wall enclosing the rear side of the interior space, and a pair of side walls enclosing the left and right sides of the interior space. The opening  85  is formed in the front side of the mounting case  150  opposing the rear wall. In other words, when the cover  87  is placed in the open position, the opening  85  exposes the interior space of the mounting case  150  to the outside of the printer  10 . 
     The cartridges  200  are mounted in the mounting case  150  and removed from the mounting case  150  through the opening  85  formed in the housing  14 . More specifically, the cartridges  200  pass through the opening  85  rearward when mounted in the mounting case  150  and pass through the opening  85  forward when removed from the mounting case  150 . The cartridge  200  mounted in the mounting case  150  is an example of the first cartridge of the present disclosure. 
     &lt;Contacts  152 &gt; 
     The contacts  152  are disposed on the top wall of the mounting case  150 . The contacts  152  protrude downward from the top wall into the interior space of the mounting case  150 . The contacts  152  are disposed in positions for contacting electrodes  248  (described later) of the corresponding cartridges  200  when the cartridges  200  are in their mounted states in the mounting case  150 . The contacts  152  are electrically conductive and capable of elastically deforming in the up-down direction  7 . The contacts  152  are electrically connected to a controller  130  described later. 
     &lt;Rods  153 &gt; 
     The rods  153  protrude forward from the rear wall of the mounting case  150 . The rods  153  are disposed in positions along the rear wall of the mounting case  150  above corresponding joints  180  (described later). As a cartridge  200  is mounted in the mounting case  150 , the corresponding rod  153  is inserted into a corresponding air valve chamber  214  (described later) through a corresponding air communication port  221  (described later) of the cartridge  200 . When the rod  153  advances into the air valve chamber  214 , the air valve chamber  214  becomes able to communicate with the atmosphere. 
     &lt;Mounting Sensors  32 &gt; 
     The mounting sensors  32  are disposed on the top wall of the mounting case  150  for detecting whether corresponding cartridges  200  are mounted in the mounting case  150 . Each mounting sensor  32  is provided with a light-emitting part and a light-receiving part that are separated from each other in the left-right direction  9 . When a cartridge  200  is mounted in the mounting case  150 , a light-blocking rib  245  (described later) on the cartridge  200  is positioned between the light-emitting part and light-receiving part of the corresponding mounting sensor  32 . In other words, the light-emitting part and light-receiving part of the mounting sensor  32  are positioned in a state opposing each other on opposite sides of the light-blocking rib  245  provided on the cartridge  200  mounted in the mounting case  150 . 
     The mounting sensor  32  outputs a different signal (hereinafter called a “mounting signal”) depending on whether the light emitted from the light-emitting part in the left-right direction  9  is received by the light-receiving part. The mounting sensor  32  outputs a low level signal to the controller  130  when the intensity of light received by the light-receiving part is less than a threshold intensity, for example. The mounting sensor  32  outputs a high level signal having a greater signal intensity than the low level signal to the controller  130  when the intensity of light received by the light-receiving part is greater than or equal to the threshold intensity. 
     &lt;Liquid Level Sensors  33 &gt; 
     Each of the liquid level sensors  33  is provided for detecting whether a detectable part  194  of a corresponding actuator  190  described later is at a detection position. The liquid level sensor  33  is provided with a light-emitting part and a light-receiving part that are separated from each other in the left-right direction  9 . In other words, when the detectable part  194  is in the detection position, the detectable part  194  is disposed between the light-emitting part and light-receiving part of the corresponding liquid level sensor  33 . On the other hand, when the detectable part  194  is not in the detection position, the detectable part  194  is not interposed between the light-emitting part and light-receiving part of the liquid level sensor  33 . The liquid level sensor  33  outputs a different signal (hereinafter called a “liquid level signal”) depending on whether the light-receiving part has received light outputted from the light-emitting part. For example, the liquid level sensor  33  outputs a low level signal to the controller  130  when the intensity of light received by the light-receiving part is less than a threshold intensity and outputs a high level signal having a greater signal intensity than the low level signal to the controller  130  when the intensity of light received by the light-receiving part is greater than or equal to the threshold intensity. 
     &lt;Locking Pin  156 &gt; 
     The locking pin  156  is a rod-shaped member that extends in the left-right direction  9  through the upper portion of the interior space in the mounting case  150  and near the opening  85 . The ends of the locking pin  156  in the left-right direction  9  are fixed in the corresponding side walls of the mounting case  150 . The locking pin  156  extends in the left-right direction  9  through the four spaces for accommodating the four cartridges  200 . When the cartridges  200  are mounted in the mounting case  150 , the locking pin  156  functions to retain the cartridges  200  in their mounted positions illustrated in  FIG.  6   . The cartridges  200  are fixed to the locking pin  156  when in their mounted states in the mounting case  150 . 
     &lt;Ink Tanks  160 &gt; 
     The printer  10  is provided with four ink tanks  160  corresponding to the four cartridges  200 . Specifically, the printer  10  is provided with an ink tank  160  that accommodates magenta ink to correspond with the cartridge  200  that accommodates magenta ink, an ink tank  160  that accommodates cyan ink to correspond to the cartridge  200  that accommodates cyan ink, an ink tank  160  that accommodates yellow ink to correspond to the cartridge  200  that accommodates yellow ink, and an ink tank  160  that accommodates black ink to correspond to the cartridge  200  that accommodates black ink. Since the four ink tanks  160  share the same general structures, only one of the ink tanks  160  is described below. The ink tank  160  is an example of the tank of the present disclosure. 
     The ink tanks  160  are positioned rearward of the rear wall constituting the mounting case  150 . As illustrated in  FIG.  4   , each ink tank  160  is configured of a top wall  161 , a front wall  162 , a bottom wall  163 , a rear wall  164 , and a pair of side walls (not illustrated). Note that the front wall  162  is configured of a plurality of walls offset from each other in the front-rear direction  8 . A liquid chamber  171  is formed inside each ink tank  160 . The liquid chamber  171  is an example of the second chamber of the present disclosure. 
     Of the walls constituting the ink tank  160 , at least the wall confronting the liquid level sensor  33  is translucent. Accordingly, light outputted by the liquid level sensor  33  can pass through the wall confronting the liquid level sensor  33 . At least part of the rear wall  164  may be a film that is affixed to the rear edges of the top wall  161 , bottom wall  163 , and side walls. The side walls of the ink tank  160  may be shared with the side walls of the mounting case  150  or may be provided independently of the mounting case  150 . Further, the ink tanks  160  are separated from each other by partitions (not illustrated) disposed between ink tanks  160  neighboring each other in the left-right direction  9 . 
     The liquid chamber  171  is in communication with an ink channel (not illustrated) through an outlet  174 . The bottom end of the outlet  174  is defined in the bottom wall  163  that defines the bottom of the liquid chamber  171 . The outlet  174  is positioned lower than a corresponding joint  180  (and specifically, the bottom end of a through-hole  184 ; described later). The ink channel that communicates with the outlet  174  is also in communication with the corresponding tube  19 . With this configuration, the liquid chamber  171  communicates with the recording head  21  via the ink channel leading from the outlet  174 , and the tube  19 . Hence, ink accommodated in the liquid chamber  171  is supplied to the recording head  21  through the ink channel leading from the outlet  174 , and the tube  19 . One end of the ink channel and tube  19  that communicates with the outlet  174  (the end at the outlet  174 ) is in communication with the liquid chamber  171 , while another end  89  (see  FIG.  3   ) is in communication with the recording head  21 . 
     The liquid chamber  171  is in communication with the atmosphere via an air communication chamber  175 . More specifically, the air communication chamber  175  is in communication with the liquid chamber  171  via a through-hole  176  that penetrates the front wall  162 . The air communication chamber  175  is also in communication with the exterior of the printer  10  through an air communication port  177  and a tube (not illustrated) connected to the air communication port  177 . That is, one end of the air communication chamber  175  (the end at the through-hole  176 ) is in communication with the liquid chamber  171 , while the other end (the end at the air communication port  177 ) is in communication with the exterior of the printer  10 . Thus, the air communication chamber  175  communicates with the atmosphere through the air communication port  177  and the tube. 
     &lt;Joints  180 &gt; 
     As illustrated in  FIG.  4   , the mounting case  150  is provided with joints  180  to correspond to the four cartridges  200 . Each joint  180  is provided with a needle  181 , and a guide  182 . The needle  181  is a tube with a channel formed in the interior thereof. The needle  181  protrudes forward from the front wall  162  defining the liquid chamber  171 . An opening  183  is formed in the front end of the needle  181 . The interior space of the needle  181  is in communication with the liquid chamber  171  via a through-hole  184  that penetrates the front wall  162 . One end of the needle  181  (the end with the opening  183 ) communicates with the outside of the ink tank  160 , and the other end (the end adjacent to the through-hole  184 ) communicates with the liquid chamber  171 . The guide  182  is a cylindrically shaped member arranged around the needle  181 . The guide  182  protrudes forward from the front wall  162  and is open on the front end. 
     A valve  185  and a coil spring  186  are positioned in the interior space of the needle  181 . The valve  185  can move in the front-rear direction  8  within the interior space of the needle  181  between a closed position and an open position. The valve  185  closes the opening  183  when in the closed position and opens the opening  183  when in the open position. The coil spring  186  urges the valve  185  forward, i.e., in a direction for moving the valve  185  from its open position to its closed position. 
     &lt;Actuator  190 &gt; 
     As illustrated in  FIG.  4   , an actuator  190  is disposed in each liquid chamber  171 . 
     Support member  195  disposed in the liquid chamber  171  supports the actuator  190  so that the actuator  190  can pivot in directions indicated by the arrows  198  and  199 . The actuator  190  can pivot between the position indicated by solid lines in  FIG.  4    and the position indicated by dashed lines. A stopper (not illustrated), such as the inner wall of the liquid chamber  171 , restricts the actuator  190  from pivoting farther in the direction indicated by the arrow  198  from the position indicated by solid lines. The actuator  190  is provided with a float  191 , shafts  192 , an arm  193 , and a detectable part  194 . 
     The float  191  is formed of a material having a smaller specific gravity than that of the ink accommodated in the liquid chamber  171 . The shafts  192  protrude outward in the left-right direction  9  from the right surface and left surface of the float  191 . The shafts  192  are inserted into holes (not illustrated) formed in the support member  195 . Through this configuration, the actuator  190  is supported by the support member  195  so as to be pivotable about the shafts  192 . The arm  193  extends substantially upward from the float  191 . The detectable part  194  is positioned on the distal end of the arm  193 . Hence, the arm  193  is positioned between the detectable part  194  and float  191 . The detectable part  194  is a plate-like member expanding in the up-down direction  7  and front-rear direction  8 . The detectable part  194  is formed of a material or in a color that blocks light outputted from the light-emitting part of the liquid level sensor  33 . 
     When the level of ink in the liquid chamber  171  is at a reference position P or higher, the buoyancy exerted on the float  191  causes the actuator  190  to pivot in the direction of the arrow  198  while the stopper maintains the actuator  190  in a detection position indicated by the solid lines illustrated in  FIG.  4   . However, when the level of ink is lower than the reference position P, the actuator  190  pivots in the direction indicated by the arrow  199  as the ink level drops. Consequently, the detectable part  194  of the actuator  190  gradually moves out of the detection position. Since the detectable part  194  is part of the actuator  190 , the position of the detectable part  194  is dependent on the quantity of ink accommodated in the liquid chamber  171 . 
     The reference position P is the same position in the up-down direction  7  as that of the axial center of the needle  181 . The reference position P is also the same position in the up-down direction  7  as that of the center of an ink supply opening  234  described later. However, the reference position P is not limited to the position described above, provided that the reference position P is set higher than the outlet  174  in the up-down direction  7 . As an example, the reference position P may be set to the height of the top or bottom of the interior space in the needle  181  or may be set to the height of the top or bottom of the ink supply opening  234 . 
     When the level of ink accommodated in the liquid chamber  171  is at the reference position P or higher, light outputted from the light-emitting part of the liquid level sensor  33  is blocked by the detectable part  194  since the detectable part  194  is in the detection position. Consequently, the light from the light-emitting part does not reach the light-receiving part, and the liquid level sensor  33  outputs a low level signal to the controller  130 . However, when the level of ink accommodated in the liquid chamber  171  is lower than the reference position P, the light outputted from the light-emitting part reaches the light-receiving part, and the liquid level sensor  33  outputs a high level signal to the controller  130 . In this way, the controller  130  can detect whether the ink level in the liquid chamber  171  is greater than or equal to the reference position P according to the liquid level signal outputted from the liquid level sensor  33 . The ink tank  160 , mounting case  150 , and recording head  21  are an example of the recording device of the present disclosure. 
     &lt;Cartridges  200 &gt; 
     The cartridge  200  is a receptacle having a liquid chamber  210  (see  FIG.  3   ) that can accommodate ink as an example of the printing agent. The liquid chamber  210  is an example of the first chamber of the present disclosure. 
     The liquid chamber  210  is defined by walls formed of a resin material, for example. As illustrated in  FIG.  5 A , the cartridge  200  is formed in a flattened shape, whereby its dimensions in the up-down direction  7  and front-rear direction  8  are greater than the dimension in the left-right direction  9 . Cartridges  200  that store different colors of ink may be formed in the same external shape or different external shapes. At least a portion of the walls configuring the cartridge  200  is translucent, enabling a user to view the level of ink accommodated in the liquid chamber  210  of the cartridge  200  from the outside. 
     The cartridge  200  is provided with a housing  201 , and an ink supply tube  230 . The housing  201  is configured of a rear wall  202 , a front wall  203 , a top wall  204 , a bottom wall  205 , and a pair of side walls  206  and  207 . Note that the rear wall  202  is configured of a plurality of walls offset from each other in the front-rear direction  8 . The top wall  204  is also configured of a plurality of walls that are offset from each other in the up-down direction  7 . Similarly, the bottom wall  205  is configured of a plurality of walls that are offset from each other in the up-down direction  7 . 
     As illustrated in  FIG.  5 B , the liquid chamber  210 , an ink valve chamber  213 , and an air valve chamber  214  are formed in the interior space of the cartridge  200 . The liquid chamber  210  has an upper liquid chamber  211 , and a lower liquid chamber  212 . The upper liquid chamber  211 , lower liquid chamber  212 , and air valve chamber  214  constitute the interior space of the housing  201 . The ink valve chamber  213  constitutes the interior space of the ink supply tube  230 . The liquid chamber  210  accommodates ink. The air valve chamber  214  provides communication between the liquid chamber  210  and the exterior of the cartridge  200 . 
     The upper liquid chamber  211  and lower liquid chamber  212  of the liquid chamber  210  are separated from each other in the up-down direction  7  by a partitioning wall  215  that divides the interior space of the housing  201 . The upper liquid chamber  211  and lower liquid chamber  212  are in communication via a through-hole  216  formed in the partitioning wall  215 . The upper liquid chamber  211  and air valve chamber  214  are separated from each other by a partitioning wall  217  that divides the interior space of the housing  201 . The upper liquid chamber  211  and air valve chamber  214  are in communication with each other via a through-hole  218  formed in the partitioning wall  217 . In addition, the ink valve chamber  213  is in communication with the bottom of the lower liquid chamber  212  via a through-hole  219 . 
     In the top of the cartridge  200 , the air valve chamber  214  communicates with the outside of the cartridge  200  via an air communication port  221  formed in the rear wall  202 . Hence, one end of the air valve chamber  214  (the end near the through-hole  218 ) communicates with the liquid chamber  210  (and more specifically the upper liquid chamber  211 ), while the other end (the end at the air communication port  221 ) communicates with the exterior of the cartridge  200 . The air valve chamber  214  is in communication with the atmosphere via the air communication port  221 . A valve  222  and a coil spring  223  are also disposed in the air valve chamber  214 . The valve  222  can move in the front-rear direction  8  between a closed position and an open position. The valve  222  closes the air communication port  221  when in the closed position and opens the air communication port  221  when in the open position. The coil spring  223  urges the valve  222  rearward, i.e., in a direction for moving the valve  222  from the open position to the closed position. 
     As the cartridge  200  is mounted in the mounting case  150 , the corresponding rod  153  is inserted through the air communication port  221  into the air valve chamber  214 . The rod  153  inserted into the air valve chamber  214  moves the valve  222  forward from its closed position against the urging force of the coil spring  223 . By moving the valve  222  into the open position, the rod  153  allows the upper liquid chamber  211  to communicate with the atmosphere. Note that the structure for opening the air communication port  221  is not limited to the example described above. As another example, the air communication port  221  may be sealed by a film, and the rod  153  may be configured to puncture the film. 
     The ink supply tube  230  protrudes rearward from the rear wall  202  beneath the housing  201 . The rear end of the ink supply tube  230  is open. In other words, the ink valve chamber  213  provides communication between the liquid chamber  210  via the through-hole  219  and the outside of the cartridge  200 . One end of the ink valve chamber  213  (the end with the through-hole  219 ) communicates with the liquid chamber  210  (and more specifically the lower liquid chamber  212 ), and the other end (the end with an ink supply opening  234  described later) communicates with the outside of the cartridge  200 . A packing  231 , a valve  232 , and a coil spring  233  are disposed in the ink valve chamber  213 . 
     An ink supply opening  234  is formed in the center of the packing  231  and penetrates the packing  231  in the front-rear direction  8 . The inner diameter of the ink supply opening  234  is slightly smaller than the outer diameter of the needle  181 . The valve  232  is capable of moving in the front-rear direction  8  between a closed position and an open position. When in the closed position, the valve  232  contacts the packing  231  and closes the ink supply opening  234 . When in the open position, the valve  232  is separated from the packing  231 , opening the ink supply opening  234 . The coil spring  233  urges the valve  232  rearward, i.e., in the direction for moving the valve  232  from the open position to the closed position. The urging force of the coil spring  233  is greater than that of the coil spring  186 . 
     As the cartridge  200  is mounted in the mounting case  150 , the ink supply tube  230  advances into the guide  182 , and the needle  181  gradually passes through the ink supply opening  234  and advances into the ink valve chamber  213 . At this time, the needle  181  elastically deforms the packing  231  while closely contacting the inner circumferential surface of the packing  231  defining the ink supply opening  234 . When the cartridge  200  is inserted farther into the mounting case  150 , the needle  181  moves the valve  232  forward against the urging force of the coil spring  233 . At the same time, the valve  232  moves the valve  185  that protrudes out from the opening  183  of the needle  181  in a rearward direction against the urging force of the coil spring  186 . 
     Through this operation, the ink supply opening  234  and opening  183  are opened so that the ink valve chamber  213  in the ink supply tube  230  is in communication with the interior space of the needle  181 . In other words, through the process of mounting the cartridge  200  in the mounting case  150 , the ink valve chamber  213  and the interior space of the needle  181  configure a channel that provides communication between the liquid chamber  210  of the cartridge  200  and the liquid chamber  171  of the ink tank  160 . 
     Also, by mounting the cartridge  200  in the mounting case  150 , a portion of the liquid chamber  210  and a portion of the liquid chamber  171  overlap each other vertically when viewed along a horizontal direction. Further, the bottom of the liquid chamber  171  is positioned lower than the bottom of the liquid chamber  210 . Thus, ink accommodated in the liquid chamber  210  flows through the connected ink supply tube  230  and joint  180  into the liquid chamber  171  of the ink tank  160  owing to the difference in hydraulic head between the liquid chamber  210  and liquid chamber  171 . 
     As illustrated in  FIGS.  5 A and  5 B , a protrusion  241  is formed on the top wall  204 . The protrusion  241  protrudes upward from the outer surface of the top wall  204  and extends in the front-rear direction  8 . The protrusion  241  has a locking surface  242 , and a sloped surface  243 . The locking surface  242  and sloped surface  243  are positioned above the top wall  204 . The locking surface  242  faces forward and expands along the up-down direction  7  and left-right direction  9 . In other words, the locking surface  242  is substantially orthogonal to the top wall  204 . The sloped surface  243  slopes relative to the top wall  204  so as to face diagonally upward and rearward. 
     The locking surface  242  is contacted by the locking pin  156  when the cartridge  200  is mounted in the mounting case  150 . The sloped surface  243  functions to guide the locking pin  156  into a position for contacting the locking surface  242  as the cartridge  200  is being mounted in the mounting case  150 . Through this contact between the locking surface  242  and locking pin  156 , the cartridge  200  is maintained in the mounted position illustrated in  FIG.  6    against the urging forces of the coil springs  186 ,  223 , and  233 . 
     A plate-shaped member is formed on the front side of the locking surface  242  and extends upward from the top wall  204 . The top surface of this plate-shaped member constitutes an operating part  244  that the user operates in order to extract the cartridge  200  from the mounting case  150 . When the cartridge  200  is mounted in the mounting case  150  and the cover  87  is in its open position, the user can operate the operating part  244 . When the user presses downward on the operating part  244 , the cartridge  200  pivots so that the locking surface  242  moves below the locking pin  156 . In this state, the user can extract the cartridge  200  from the mounting case  150 . 
     As illustrated in  FIGS.  5 A and  5 B , a light-blocking rib  245  is formed on the outer surface of the top wall  204  to the rear of the protrusion  241 . The light-blocking rib  245  protrudes upward from the outer surface of the top wall  204  and extends in the front-rear direction  8 . The light-blocking rib  245  is formed of a material or in a color capable of blocking light outputted from the light-emitting part of the mounting sensor  32 . When the cartridge  200  is in its mounted state in the mounting case  150 , the light-blocking rib  245  is positioned in the optical path of the light traveling from the light-emitting part to the light-receiving part of the mounting sensor  32 . Hence, the mounting sensor  32  outputs a low level signal to the controller  130  when the cartridge  200  is mounted in the mounting case  150 . Conversely, the mounting sensor  32  outputs a high level signal to the controller  130  when the cartridge  200  is not mounted in the mounting case  150 . Therefore, the controller  130  can detect whether a cartridge  200  is mounted in the mounting case  150  according to the mounting signal outputted from the corresponding mounting sensor  32 . 
     As illustrated in  FIGS.  5 A and  5 B , an IC chip  34  is positioned on the outer surface of the top wall  204  between the light-blocking rib  245  and protrusion  241  in the front-rear direction  8 . Electrodes  248  are formed on the IC chip  34 . The IC chip  34  is also provided with a memory (not illustrated). The electrodes  248  are electrically connected to the memory on the IC chip  34 . The electrodes  248  are exposed on the top surface of the IC chip  34  so as to be capable of conducting electricity with the corresponding contact  152  provided in the mounting case  150 . In other words, the electrodes  248  are electrically connected to the contact  152  when the cartridge  200  is mounted in the mounting case  150 . The controller  130  can read information from the memory on the IC chip  34  through the contact  152  and electrodes  248  and can write information to the memory of the IC chip  34  through the contact  152  and electrodes  248 . 
     The memory on the IC chip  34  stores type information, a serial number, and a cartridge residual quantity for the cartridge  200 . The type information indicates whether the cartridge  200  is a small-capacity cartridge or a large-capacity cartridge and indicates the color of ink accommodated therein. The serial number is information that uniquely identifies the cartridge  200 . The cartridge residual quantity is a value specifying the quantity of ink accommodated in the cartridge  200 . Note that for unused cartridges  200 , an initial fill quantity specifying the initial quantity of ink in the cartridge  200  is stored in a memory as the cartridge residual quantity. 
     &lt;Controller  130 &gt; 
     The printer  10  is provided with a controller  130 . As illustrated in  FIG.  1   , the controller  130  is provided with a central processing unit (CPU)  35 , a storage unit  36 , and a communication bus  39 . The storage unit  36  has a read only memory (ROM)  37  that stores programs and data, and an electrically erasable programmable read only memory (EEPROM)  51  and a random access memory (RAM)  52  that also store data. 
     The ROM  37  stores an operating system (OS) program  37 A, a control program  37 B, a communication program  37 C, and the like. The OS program  37 A functions to control the operations of other programs. The communication program  37 C functions to control communications with external devices such as the information collection server  40  and the like. The control program  37 B performs a printing process and the like described later. The CPU  35  executes the OS program  37 A, control program  37 B, and communication program  37 C by processing commands described at an address. In the following description, operations processed by executing the OS program  37 A, control program  37 B, and communication program  37 C may be described as the operations of the controller  130 . Note that the controller  130  may possess a hardware circuit that employs chips to implement all or some of the operations executed by the OS program  37 A, control program  37 B, and communication program  37 C. 
     The ROM  37  also stores a first prescribed value, a second prescribed value, and various threshold values described later. 
     The EEPROM  51  stores device information on the printer  10 . Device information includes the model name of the printer  10 , and printer ID for the printer  10 . This printer ID may be the MAC address, serial number, or the like of the printer  10 . 
     The EEPROM  51  also stores a first discharge value, a second discharge value, an initial cartridge residual quantity, an initial tank residual quantity, a S_Empty flag, and a C_Empty flag. The EEPROM  51  further stores initial fill quantities of cartridges  200  in association with the type information of the cartridges  200 , respectively. These values will be described in greater detail in a printing process described later. 
     The RAM  52  stores a tank residual quantity and a cartridge residual quantity described later. 
     In addition to the components described above, the printer  10  is also provided with a clock  30 , a communication interface (I/F)  31 , and a motor (not illustrated). The clock  30  outputs date and time information (hereinafter “date and time” will be called “date/time information”, and we will abbreviate “date and time” to “date/time”). The communication I/F  31  is connected to the communication circuit  6 . The recording head  21 , communication interface  31 , mounting sensors  32 , liquid level sensors  33 , contacts  152 , clock  30 , display  28 , motor, and the like are all connected to the communication bus  39 . 
     The controller  130  drives the motor (not illustrated) through the communication bus  39  to rotate the feed roller  23 , conveying rollers  25 , and discharge rollers  27 . The controller  130  also outputs drive signals via the communication bus  39  to driving elements of the recording head  21  in order to control the recording head  21  to eject ink droplets. 
     The controller  130  detects whether cartridges  200  are mounted in the mounting case  150  according to mounting signals outputted from the mounting sensors  32 . The controller  130  also detects whether the level of ink accommodated in the liquid chambers  171  of the corresponding ink tanks  160  is at or above the reference position P according to liquid level signals outputted from the liquid level sensors  33 . 
     &lt;Information Collection Server  40 &gt; 
     The information collection server  40  may be established on the communication circuit  6  by the vendor of the printer  10  or a company other than the vendor. The information collection server  40  includes a CPU  41 , a storage unit  42 , a communication I/F  43 , a communication bus  44 , and a clock  48 . The CPU  41 , storage unit  42 , and communication bus  44  constitute a controller  45 . The clock  48  outputs date/time information. The communication I/F  43  is connected to the communication circuit  6  and communicates with the printer  10  and the shipping server  50 . 
     The storage unit  42  has a program storage area  46 , and a data storage area  47 . The program storage area  46  is a hard disk or the like, and the data storage area  47  is a RAM, a hard disk, or the like. The storage unit  42  is an example of the memory of the present disclosure. 
     The data storage area  47  stores a residual quantity management list described later (see  FIG.  13 (A) ) and a cartridge management list described later (see  FIG.  13 (B) ). 
     The program storage area  46  stores various programs, including an OS program  46 A, a control program  46 B, and a communication program  46 C. The OS program  46 A controls the operations of other programs. The control program  46 B executes an ordering process described later and the like. The communication program  46 C controls communications with the printer  10  and shipping server  50 . The OS program  46 A, control program  46 B, and communication program  46 C are copied from the program storage area  46  to data storage area  47  as a series of commands to be executed sequentially by the CPU  41 . In the following description, the operations processed by executing the OS program  46 A, control program  46 B, and communication program  46 C will be described as the operations of the controller  45  or the information collection server  40 . The control program  46 B is an example of the set of program instructions of the present disclosure. 
     &lt;Shipping Server  50 &gt; 
     The shipping server  50  may be established on the communication circuit  6  by the vendor of the printer  10  or by a company other than the vendor. The shipping server  50  provides a service of shipping cartridges  200  to users of printers  10  in response to requests (order commands) from the information collection server  40 . 
     &lt;Ink Management with the Ordering System  5 &gt; 
     In the ordering system  5 , the information collection server  40  collects management information from printers  10  that includes information for residual quantity of ink. When the residual quantity of ink becomes low, the information collection server  40  issues an order to the shipping server  50  for a cartridge  200 . Since the information collection server  40  can manage residual quantities of ink and order cartridges  200  when needed, this ordering system  5  provides convenience to the user by eliminating the time and effort the users of printers  10  expend to manage residual ink quantities and to purchase cartridges  200 . 
     Specifically, the user of each printer  10  enters a contract with the manufacturer that provides a service to manage residual ink quantities and to place orders for cartridges  200 . A contract for this ink management and cartridge ordering service is entered for each printer. When a contract is entered, the user&#39;s information and printer ID for the printer  10  under contract is stored on the information collection server  40 . The user information is information relevant to the shipping destination of the cartridges  200 , such as the user&#39;s name and address. 
     Once the user and manufacturer enter this contract, the printer ID for the printer  10  and the user information are stored on the information collection server  40  in association with each other. The processes performed on the printer  10 , information collection server  40 , and shipping server  50  in relation to the ordering of cartridges  200  will be described below in greater detail. 
     &lt;Processes Executed by the Controller  130  of the Printer  10 &gt; 
     Next, processes executed by the controller  130  of the printer  10  will be described with reference to  FIGS.  7  through  9 B . Note that the order in which the steps described below are executed may be modified as desired without departing from the spirit of the present disclosure. 
     &lt;Printing Process&gt; 
     The controller  130  executes the printing process illustrated in  FIG.  7    when a print command is inputted into the printer  10 . While there is no particular restriction on the source of the print command, the controller  130  may receive user operations for a print command through the operating panel  22  or the display  28 , or may receive user operations for a print command from an external device via the communication I/F  31 . The print command includes image data representing an image to be printed. The controller  130  stores the image data in the RAM  52  of the printer  10 . 
     In S 11  at the beginning of the printing process, the controller  130  determines whether the value of the S_Empty flag is “ON” or “OFF.” The controller  130  sets the S_Empty flag in the EEPROM  51  to “ON” prior to the level of ink in the liquid chamber  171  of the corresponding ink tank  160  dropping to the top of the outlet  174  through which ink flows out of the ink tank  160 . Before the controller  130  sets the S_Empty flag to “ON,” the S_Empty flag stored in the EEPROM  51  is set to an initial value of “OFF.” Note that there is a possibility air could enter the nozzles of the recording head  21  after the level of ink reaches the top of the outlet  174 . If air were to enter the nozzles in the recording head  21  and become retained therein, the retained air could obstruct the flow of ink into the nozzles or obstruct the ejection of ink droplets from the nozzles. 
     Hence, the S_Empty flag serves to prevent air from being introduced into the nozzles of the recording head  21 . As will be described later, the controller  130  sets the S_Empty flag in the EEPROM  51  to “OFF” in step S 14  and sets the S_Empty flag to “ON” in step S 55  of  FIG.  8 D . Although not illustrated in the flowchart, the controller  130  prohibits the ejection of ink from the recording head  21  when the S_Empty flag is set to “ON” and allows the ejection of ink when the S_Empty flag is set to “OFF.” 
     If the controller  130  determines in S 11  that the S_Empty flag is set to the value “ON” (S 11 : ON), the controller  130  begins acquiring the mounting signal from the corresponding mounting sensor  32  at prescribed intervals. In S 12  the controller  130  determines whether the acquired mounting signal changed from a low level signal (hereinafter simply called “L”) to a high level signal (hereinafter simply called “H”) and whether the mounting signal subsequently changed from “H” to “L”. That is, the controller  130  determines whether a cartridge  200  was mounted on the basis of changes in the mounting signal. In the following description, the controller  130  determining whether the acquired mounting signal changed from “L” to “H” and subsequently from “H” to “L” will be described as the controller  130  determining whether the cartridge  200  has been replaced. Further the controller  130  will determine that a cartridge  200  has been mounted (that is, a new cartridge  200  has been replaced with the previous cartridge  200 ) when determining in S 12  that the acquired mounting signal changed from “L” to “H” and subsequently changed from “H” to “L” (S 12 : YES). 
     While a cartridge  200  has not been mounted (that is, while a new cartridge  200  has not been replaced with the previous cartridge  200 ) (S 12 : NO), the controller  130  continues periodically acquiring the mounting signal from the mounting sensor  32 . When the controller  130  determines that a cartridge  200  has been mounted (S 12 : YES), the controller  130  executes a first updating process in S 13 . 
     Note that while the process in S 12  is given as an example by which the controller  130  determines whether a cartridge  200  has been mounted, the determination is not limited to this process. For example, the controller  130  may determine whether a cartridge  200  has been mounted on the basis of a serial number. In this case, the controller  130  reads the serial number of a cartridge  200  from the memory on the IC chip  34  of the cartridge  200 . Subsequently, the controller  130  determines whether the serial number read from the memory matches a serial number stored in the EEPROM  51 . The serial numbers stored in the EEPROM  51  are those serial numbers stored in the memory of IC chips  34  disposed on cartridges  200  (previous cartridges  200 ) that were mounted in the mounting case  150  prior to a new cartridge  200  being mounted in the mounting case  150 . Thus, in this case the controller  130  determines that a cartridge  200  has been mounted when the serial number read from the memory of the IC chip  34  does not match a serial number stored on the EEPROM  51 . 
     &lt;First Updating Process&gt; 
     The controller  130  executes the first updating process illustrated in  FIG.  8 A  so as to update the initial cartridge residual quantity and initial tank residual quantity stored in the EEPROM  51  and the cartridge residual quantity sored in the IC chip  34  on a cartridge  200 , when the cartridge  200  has just been mounted in the mounting case  150  of the printer  10 . 
     In S 31  at the beginning of the first updating process, the controller  130  reads the cartridge residual quantity from the memory on the IC chip  34  of the cartridge  200  mounted in the mounting case  150  through the contact  152 . In S 32  the controller  130  stores the cartridge residual quantity read in S 31  in the EEPROM  51  as the initial cartridge residual quantity. 
     In S 33  the controller  130  reads a tank residual quantity from the RAM  52 . Note that if a tank residual quantity is not stored in the RAM  52  due to an interruption in power supply or the like, the controller  130  calculates a tank residual quantity and stores this calculated value in the RAM  52 , similar to a fourth updating process described later. The tank residual quantity read from the RAM  52  indicates the residual quantity of ink accumulated in the liquid chamber  171  of the ink tank  160  just prior to the cartridge  200  being mounted. In other words, the tank residual quantity indicates the quantity of ink that had accumulated in the liquid chamber  171  of the ink tank  160  when the previous cartridge  200  was removed. In S 33  the controller  130  stores the tank residual quantity read from the RAM  52  in the EEPROM  51  as the initial tank residual quantity. 
     In S 34  the controller  130  adds the initial tank residual quantity to the initial cartridge residual quantity to calculate a total residual quantity specifying the total quantity of residual ink. In S 35  the controller  130  sets a new cartridge residual quantity and new tank residual quantity on the basis of the calculated total residual quantity. 
     To describe this in greater detail, when a new cartridge  200  is mounted in the mounting case  15 , a portion of the ink accommodated in the liquid chamber  210  of the new cartridge  200  flows out of the liquid chamber  210  into the liquid chamber  171  of the ink tank  160 . This flow of ink from the liquid chamber  210  of the cartridge  200  into the liquid chamber  171  of the ink tank  160  stops when the difference in the hydraulic head between ink accommodated in the liquid chamber  210  and ink accommodated in the liquid chamber  171  becomes negligible. The new cartridge residual quantity and new tank residual quantity indicate residual ink quantities when there is little difference in hydraulic head between ink accommodated in the liquid chamber  210  of the cartridge  200  and ink accommodated in the liquid chamber  171  of the ink tank  160 . 
     The controller  130  may calculate the cartridge residual quantity and tank residual quantity according to formulae stored in the EEPROM  51  or ROM  37 , for example. 
     Alternatively, the controller  130  may set the cartridge residual quantity and tank residual quantity according to tables stored in the EEPROM  51  or ROM  37 , for example. More specifically, the shape of the liquid chamber  210  in the cartridge  200  and the shape of the liquid chamber  171  in the ink tank  160  are predetermined according to design. Therefore, by knowing the total residual quantity of ink, it is also possible to determine the cartridge residual quantity and tank residual quantity when the hydraulic head difference between ink accommodated in the cartridge  200  and ink accommodated in the ink tank  160  is almost nothing. Thus, formulae for calculating the cartridge residual quantity and tank residual quantity from a total residual quantity are prestored in the EEPROM  51  or ROM  37 . Alternatively, tables showing correlations between cartridge residual quantities and tank residual quantities, and total residual quantities may be prestored in the EEPROM  51  or ROM  37 . The controller  130  sets a new cartridge residual quantity and a new tank residual quantity according to the formulae or tables. 
     In S 36  the controller  130  stores the new cartridge residual quantity in the RAM  52  and updates the cartridge residual quantity stored in the memory on the IC chip  34 . In S 37  the controller  130  stores the new tank residual quantity in the RAM  52 . Subsequently, the controller  130  ends the first updating process. 
     After completing the first updating process of S 13  illustrated in  FIG.  7   , in S 14  the controller  130  sets the S_Empty flag to “OFF” in the EEPROM  51 , sets the C_Empty flag in the EEPROM  51  to “OFF,” sets a cartridge replacement flag to “ON” in the EEPROM  51 , and resets the first discharge value and second discharge value to “zero.” Subsequently, the controller  130  repeats the process described above from S 11 . Here, the C_Empty flag, first discharge value, second discharge value, and cartridge replacement flag will be described later. 
     If the controller  130  determines in S 11  that the S_Empty flag is set to “OFF” (S 11 : OFF), in S 15  the controller  130  acquires the liquid level signal from the liquid level sensor  33 . In S 16  the controller  130  performs a printing operation on a sheet according to image data stored in the RAM  52 . By printing an image on a sheet, ink is discharged from the recording head  21 , lowering the level of ink in the ink tank  160 . After completing the printing operation in S 16 , in S 17  the controller  130  acquires a liquid level signal from the liquid level sensor  33 . In S 18  the controller  130  determines the change of the pair of liquid level signals acquired in S 15  and S 17 . In the following description, a low level signal acquired from the liquid level sensor  33  will simply be called “L” and a high level signal acquired from the liquid level sensor  33  will simply be called “H”. 
     If the controller  130  determines that the liquid level signals acquired in S 15  and S 17  are both “L” (S 18 : L—&gt;L), the controller  130  executes a second updating process in S 19 . When the controller  130  determines in S 18  that the liquid level signals acquired in S 15  and S 17  are both “L”, the level of ink stored in the liquid chamber  171  of the ink tank  160  prior to the printing operation in S 16  being executed was at the reference position P or higher (since a liquid level signal of “L” was acquired in S 15 ), and similarly the level of ink stored in the liquid chamber  171  of the ink tank  160  after the printing operation of S 16  was executed is at the reference position P or higher (since a liquid level signal of “L” was acquired in S 17 ). In other words, when the controller  130  acquires a liquid level signal of “L” in S 17  after executing a printing operation in S 16 , ink still remains in the liquid chamber  210  of the cartridge  200 . 
     &lt;Second Updating Process&gt; 
     The controller  130  executes the second updating process illustrated in  FIG.  8 B  so as to set a new cartridge residual quantity and a new tank residual quantity based on a first discharge value specifying the quantity of ink discharge through the recording head  21  during printing and maintenance, when ink still remains in the liquid chamber  210  of the cartridge  200 . The first discharge value is found by multiplying the quantity of one ink droplet ejected from the recording head  21  by the number of ink droplets ejected, for example. Each time the controller  130  gives a command to eject ink from the recording head  21 , the controller  130  calculates the first discharge value based on this command. The controller  130  calculates a first discharge value that corresponds to the total quantity of ink ejected by the recording head  21  from the moment the cartridge  200  was mounted in the mounting case  150  to the present. Hence, the first discharge value is the cumulative quantity of ink ejected by the recording head  21  since the cartridge  200  was mounted. The first discharge value is stored in the EEPROM  51 . 
     In S 41  at the beginning of the second updating process, the controller  130  reads the initial cartridge residual quantity and the initial tank residual quantity from the EEPROM  51 . In S 42  the controller  130  calculates the total residual quantity by adding the initial cartridge residual quantity and initial tank residual quantity read in S 41 . In S 43  the controller  130  calculates a new total residual quantity by subtracting the first discharge value from the total residual quantity calculated in S 42 . In S 44  the controller  130  sets a new cartridge residual quantity and a new tank residual quantity using the new total residual quantity calculated in S 43  and the formulae or tables described earlier. 
     In S 45  the controller  130  stores the new cartridge residual quantity set in S 44  in the RAM  52  and updates the cartridge residual quantity stored in memory on the IC chip  34 . In S 46  the controller  130  also stores the new tank residual quantity set in S 44  in the RAM  52 . Subsequently, the controller  130  ends the second updating process. 
     After completing the second updating process of S 19  illustrated in  FIG.  7   , in S 22  the controller  130  determines whether image data for a subsequent page is stored in the RAM  52 . If image data for a subsequent page is stored in the RAM  52  (S 22 : YES), the controller  130  returns to S 11  and repeats the process described above. However, if the controller  130  determines that image data for another page is not stored in the RAM  52  (S 22 : NO), the controller  130  ends the printing process. 
     Note that the method for setting the cartridge residual quantity and tank residual quantity described above is merely an example and these quantities may be set according to another method. 
     When the controller  130  determines in S 11  that the S_Empty flag is set to “OFF” (S 11 : OFF), the controller  130  again executes the process from S 15  to S 18 . If the controller  130  acquires the liquid level signal “L” in S 15  and acquires the liquid level signal “H” in S 17  (S 18 : L—&gt;H), the controller  130  executes a third updating process in S 20 . When the controller  130  determines in S 18  that the liquid level signal acquired in S 15  is “L” and the liquid level signal acquired in S 17  is “H”, the level of ink stored in the liquid chamber  171  of the ink tank  160  prior to execution of the printing operation in S 16  was at or higher than the reference position P (as indicated by the liquid level signal “L” acquired in S 15 ) and the level of ink stored in the liquid chamber  171  after the printing operation of S 16  was executed is lower than the reference position P (as indicated by the liquid level signal “H” acquired in S 17 ). That is, the liquid chamber  210  of the cartridge  200  became depleted of ink while the printing operation of S 16  was executed. This signifies that ink in the liquid chamber  210  of the cartridge  200  was used up during the printing operation. 
     &lt;Third Updating Process&gt; 
     The controller  130  executes the third updating process illustrated in  FIG.  8 C  so as to update the cartridge residual quantity to a first prescribed value and so as to update the tank residual quantity to a second prescribed value, when ink in the liquid chamber  210  of the cartridge  200  was just used up during the printing operation. More specifically, the first discharge value indicating the quantity of ink discharged from the recording head  21  during printing and the like includes error. For example, even though the controller  130  commands the recording head  21  to eject ink in a specific quantity, the quantity of ink actually ejected from the recording head  21  may differ from the specific quantity directed by the controller  130 . One factor of this difference may be the temperature when the ejection of ink is commanded, for example. That is, the viscosity of ink increases as temperature drops, and high-viscosity ink is more difficult to discharge through the nozzles  29 . Further, when the controller  130  repeatedly issues the above command to the recording head  21 , the difference between the quantity of ink actually discharged from the recording head  21  through these repetitions and the total amount of the specific quantity multiplied by the number of repetitions may increase. In other words, there is a possibility that the error between the quantity specified by the calculated first discharge value and the quantity actually discharged from the recording head  21  will accumulate each time a printing operation is performed. 
     Since the cartridge residual quantity is set according to this first discharge value, error is generated between the residual ink quantity specified by the cartridge residual quantity and the actual residual ink quantity in the liquid chamber  210 . Further, since the tank residual quantity is set according to the first discharge value, error is generated between the residual ink quantity specified by the tank residual quantity and the actual residual ink quantity in the liquid chamber  171 . Consequently, the cartridge residual quantity and the tank residual quantity set every printing operation include accumulated error. The third updating process is performed to reset this accumulated error. 
     Specifically, in S 47  of  FIG.  8 C , the controller  130  updates the cartridge residual quantities stored both in the RAM  52  and the memory on the IC chip  34  to the first prescribed value. The first prescribed value may be zero, for example. In S 48  the controller  130  updates the tank residual quantity in the RAM  52  to the second prescribed value. The second prescribed value indicates the quantity of ink stored in the liquid chamber  171  of the ink tank  160  when the level of ink is at the reference position P. The first prescribed value and second prescribed value are stored in the ROM  37  in advance, for example. 
     In S 49  the controller  130  sets the C_Empty flag in the EEPROM  51  to “ON” and subsequently ends the third updating process. Thus, when ink accommodated in the cartridge  200  is used up, the C_Empty flag in the EEPROM  51  stores the value “ON”. 
     After completing the third updating process of S 20  illustrated in  FIG.  7   , in S 22  the controller  130  determines whether image data for subsequent pages is stored in the RAM  52 . The controller  130  repeats the above process from S 11  when determining that image data for subsequent pages is stored in the RAM  52  (S 22 : YES) and ends the printing process when determining that image data for subsequent pages is not stored in the RAM  52  (S 22 : NO). 
     When the controller  130  determines in the process of S 11  that the S_Empty flag is set to “OFF” (S 11 : OFF), the controller  130  repeats the process in steps S 15  through S 18 . If the controller  130  determines in S 18  that the liquid level signals acquired in S 15  and S 17  are both “H” (S 18 : H—&gt;H), the controller  130  executes a fourth updating process in S 21 . When the controller  130  determines in S 18  that both liquid level signals acquired in S 15  and S 17  are “H”, the level of ink stored in the liquid chamber  171  of the ink tank  160  prior to the printing operation in S 16  being executed was lower than the reference position P (as indicated by the liquid level signal “H” acquired in S 15 ) and the level of ink stored in the liquid chamber  171  remains lower than the reference position P following the printing operation in S 16  (as indicated by the liquid level signal “H” acquired in S 17 ). In other words, the liquid chamber  210  of the cartridge  200  contains no ink before or after the controller  130  executes the printing operation in S 16 . 
     &lt;Fourth Updating Process&gt; 
     The controller  130  executes the fourth updating process illustrated in  FIG.  8 D  so that the controller  130  calculates a tank residual quantity and determines whether the quantity of ink in the ink tank  160  specified by the tank residual quantity is a sufficient quantity for continuing printing, when the printing was performed after the liquid chamber  210  of the cartridge  200  had ran out of ink. 
     In S 51  at the beginning of the fourth updating process, the controller  130  reads the tank residual quantity updated to the second prescribed value from the RAM  52  and the second discharge value from the EEPROM  51 . In S 52  the controller  130  subtracts the second discharge value from the tank residual quantity read in S 51  to find a new tank residual quantity. As with the first discharge value, the second discharge value is obtained by multiplying the quantity of one ink droplet discharged from the recording head  21  by the number of times an ink droplet was discharged, for example. Each time the controller  130  issues a command to the recording head  21  to discharge ink, the controller  130  calculates the second discharge value based on the command. The controller  130  calculates the second discharge value to indicate the quantity of ink discharged by the recording head  21  from the timing after the liquid level signal acquired from the liquid level sensor  33  changed from “L” to “H” until the present time. Thus, the second discharge value is the cumulative quantity of ink discharged by the recording head  21  since the liquid level signal changed from “L” to “H”. This second discharge value is stored in the EEPROM  51 . 
     In S 53  the controller  130  stores the new tank residual quantity calculated in S 52  in the RAM  52 . In S 54  the controller  130  determines whether the calculated second discharge value has reached a threshold value. The threshold value is stored in the ROM  37  or the EEPROM  51  in advance. When the controller  130  determines that the second discharge value has not yet reached the threshold value (S 54 : NO), the controller  130  ends the fourth updating process. However, if the controller  130  determines that the second discharge value has reached the threshold value (S 54 : YES), in S 55  the controller  130  sets the S_Empty flag in the EEPROM  51  to the value “ON”. Subsequently, the controller  130  ends the fourth updating process. While not illustrated in the flowchart, if the controller  130  determines that the S_Empty flag is set to the value “ON”, the controller  130  prevents the discharge of ink from the recording head  21  for purposes of printing or maintenance. 
     The threshold value is set such that the level of ink stored in the liquid chamber  171  of the ink tank  160  will be at a position slightly higher than the outlet  174  when the second discharge value reaches the threshold value. More specifically, error may occur between the design reference position P for performing detections with the liquid level sensor  33  and the reference position P at which the liquid level sensor  33  actually performs detections. This difference may arise from faulty operations of the actuator  190  or the like, for example. Thus, the threshold value is set such that the level of ink accommodated in the liquid chamber  171  of the ink tank  160  will not overlap the outlet  174  when the second discharge value reaches the threshold value, even if the error reaches the maximum possible value anticipated during design. By preventing ink from being discharged from the recording head  21 , the controller  130  restricts air from being introduced into the recording head  21 . Note that in addition to considerations for the error described above, the threshold value may be set such that the level of ink stored in the liquid chamber  171  of the ink tank  160  does not overlap the outlet  174  when the second discharge value reaches the threshold value, even if the printer  10  is resting on a sloped surface that slopes at a prescribed angle of inclination. In addition, the second discharge value may also include error, as with the first discharge value. Thus, the threshold value may be set such that the level of ink stored in the liquid chamber  171  of the ink tank  160  does not overlap the outlet  174  when the second discharge value reaches the threshold value, even if the second discharge value contains the maximum error. 
     After completing the fourth updating process of S 21  illustrated in  FIG.  7   , in S 22  the controller  130  determines whether image data for subsequent pages is stored in the RAM  52 . The controller  130  repeats the above process from S 11  when determining that image data for subsequent pages is stored in the RAM  52  (S 22 : YES) and ends the printing process when determining that image data for subsequent pages is not stored in the RAM  52  (S 22 : NO). 
     As described above, the controller  130  sets a cartridge residual quantity and a tank residual quantity according to the amount of ink used during printing each time the printing operation in S 16  is executed. Note that the above description covers the case in which the controller  130  sets the cartridge residual quantity and tank residual quantity each time a printing operation is executed for one page. However, the controller  130  may set the cartridge residual quantity and tank residual quantity each time printing is executed for one pass. In addition, the controller  130  may execute the second updating process, third updating process, and fourth updating process not only after printing operations, but also after ink is discharged through the recording head  21  for maintenance and the like. 
     Next, a management information transmission process will be described with reference to  FIGS.  9 A and  9 B . In this process, the printer  10  generates management information and transmits this management information to the information collection server  40 . After completing all steps of the management information transmission process, the printer  10  returns to the initial step and repeats the process. 
     In S 61  at the beginning of the management information transmission process, the controller  130  of the printer  10  determines whether date/time information outputted by the clock  30  has reached a prescribed transmission time stored in the EEPROM  51 . If the controller  130  determines that the date/time information outputted by the clock  30  has not reached the prescribed transmission time (S 61 : NO), the controller  130  ends the management information transmission process. 
     However, when the date/time information outputted by the clock  30  matches the prescribed transmission time (S 61 : YES), in S 62  the controller  130  reads the value of the C_Empty flag from the EEPROM  51  and determines whether the value is “ON”. In other words, in S 62  the controller  130  determines whether the cartridge  200  mounted in the mounting case  150  has run out of ink. 
     If the controller  130  determines that the C_Empty flag is set to “OFF” (S 62 : NO), in S 63  the controller  130  reads the initial cartridge residual quantity, the initial tank residual quantity, and an initial fill quantity from the EEPROM  51 . Note that the controller  130  reads type information for the cartridge  200  from the IC chip  34  of the cartridge  200 , and subsequently reads the initial fill quantity corresponding to this type information from the EEPROM  51 . 
     In S 64  the controller  130  reads the first discharge value from the EEPROM  51 . In S 65  the controller  130  calculates a total residual quantity by subtracting the first discharge value read in S 64  from the sum of the initial cartridge residual quantity and initial tank residual quantity read in S 63 . 
     In S 66  the controller  130  sets a new cartridge residual quantity and a new tank residual quantity based on the calculated total residual quantity, as described above in the second updating process. In S 67  the controller  130  stores the new cartridge residual quantity in the RAM  52  and on the IC chip  34 . In S 68  the controller  130  stores the new tank residual quantity in the RAM  52 . 
     In S 69  the controller  130  calculates a total residual percentage (%) by dividing the total residual quantity calculated in S 65  by the initial fill quantity read in S 63  and multiplying the result by 100. In S 70  the controller  130  determines whether the total residual percentage calculated in S 69  exceeds 100%. Cases in which the total residual percentage exceeds 100% will be described next in greater detail. 
     When a new cartridge  200  accommodating ink of an initial fill quantity is mounted in the mounting case  150  while ink still remains in the liquid chamber  171  of the ink tank  160 , the total residual quantity becomes a value that exceeds the initial fill quantity. When the total residual quantity exceeds the initial fill quantity, the total residual percentage calculated by dividing the total residual quantity by the initial fill quantity and multiplying by 100 exceeds 100%. Hence, if a new cartridge  200  accommodating ink at the initial fill quantity is mounted in the mounting case  150  while ink remains in the liquid chamber  171  of the ink tank  160 , the total residual percentage will remain over 100% until the residual ink in the liquid chamber  171  of the ink tank  160  is used. 
     If the controller  130  determines in S 70  that the total residual percentage calculated in S 69  exceeds 100% (S 70 : YES), in S 71  the controller  130  changes the total residual percentage to 100%. However, if the controller  130  determines that the total residual percentage does not exceed 100% (S 70 : NO), the controller  130  skips S 71 . 
     In S 71  the controller  130  changes the total residual percentage to 100% when the total residual percentage exceeds 100% to ensure consistency with printers that do not transmit total residual percentages exceeding 100%. A printer that does not transmit total residual percentages exceeding 100% signifies a printer provided with the mounting case  150 , but not the ink tanks  160 . Printers having a mounting case  150  but no ink tanks  160  transmit a value obtained by dividing the current residual quantity by the initial fill quantity and multiplying the result by 100 as the residual percentage. In other words, a printer that has a mounting case  150  but no ink tanks  160  transmits a residual percentage of 100% or less. Since the printer  10  modifies a total residual percentage exceeding 100% to 100%, the printer  10  can ensure consistency with printers having a mounting case  150  but no ink tanks  160 . In other words, the printer  10  can transmit a total residual percentage to an information collection server  40  incapable of processing residual percentages over 100% and direct the information collection server  40  to process this data. 
     On the other hand, if the controller  130  determines in S 62  that the C_Empty flag is set to “ON” (S 62 : YES), in S 72  the controller  130  reads the cartridge residual quantity equivalent to the first prescribed value (zero) and the tank residual quantity equivalent to the second prescribed value from the RAM  52 , and the initial fill quantity from the EEPROM  51 . In S 73  the controller  130  reads the second discharge value from the EEPROM  51 . In S 74  the controller  130  calculates a new tank residual quantity by subtracting the second discharge value read in S 73  from the tank residual quantity read in S 72 . In S 75  the controller  130  stores the new tank residual quantity calculated in S 74  in the RAM  52 . 
     In S 76  the controller  130  calculates a total residual quantity by adding the new tank residual quantity calculated in S 74  to the cartridge residual quantity read in S 72 . In S 77  the controller  130  calculates a total residual percentage by dividing the total residual quantity calculated in S 76  by the initial fill quantity read in S 72  and multiplying the result by 100. 
     In S 78  the controller  130  stores the total residual percentage calculated in S 69 , the total residual percentage modified to 100% in S 71 , or the total residual percentage calculated in S 77  in the RAM  52 . 
     In S 79  the controller  130  reads the value of the C_Empty flag, the value of the cartridge replacement flag, and the device information from the EEPROM  51 , the cartridge residual quantity, the tank residual quantity, and the total residual percentage from the RAM  52 , and the type information for the cartridge  200  from the IC chip  34 . In S 80  the controller  130  generates management information that includes the value of the C_Empty flag, the cartridge residual quantity, the tank residual quantity, the total residual percentage, the model name and printer ID for the printer  10  indicated in the device information, the type information for the cartridge  200 , and the value of the cartridge replacement flag. 
     In S 81  the controller  130  transmits this management information to the information collection server  40 . After transmitting the management information, in S 82  the controller  130  sets the cartridge replacement flag to “OFF” and subsequently ends the management information transmission process. Hence, management information transmitted after the cartridge replacement flag was set to “ON” in S 14  of  FIG.  7    includes the cartridge replacement flag with the setting “ON”, and the cartridge replacement flag is set to “OFF” after the management information including this cartridge replacement flag with the setting “ON” has been transmitted. The total residual percentage included in the management information is an example of the index value of the present disclosure. 
     The information collection server  40  receives the management information transmitted from the printer  10 . Next, an ordering process executed on the information collection server  40  that receives the management information will be described with reference to  FIG.  10   . Note that after completing all steps in the ordering process, the information collection server  40  returns to the initial step and repeats the process. 
     In S 89  at the beginning of the ordering process, the controller  45  of the information collection server  40  determines whether management information was received. If management information was not received (S 89 : NO), the controller  45  skips steps S 90  through S 95 , and performs the process of S 96  described later. However, when management information was received (S 89 : YES), in S 90  the controller  45  determines whether the cartridge replacement flag included in the management information is set to “ON”. In other words, in S 90  the controller  45  determines whether the cartridge  200  in the printer  10  has been replaced with a new cartridge  200  which was ordered. The process that the information collection server  40  receives the management information is an example of the (a) acquiring of the present disclosure. 
     If the controller  45  determines that the cartridge replacement flag is set to “ON” (S 90 : YES), in S 91  the controller  45  sets an order flag to “OFF”. More specifically, the controller  45  sets an order flag stored in a cartridge management list (described later) in association with the type information for the cartridge  200  and the printer ID included in the management information to “OFF”. The order flag is provided to prevent the cartridge  200  from placing duplicate orders. This concept will be described later. On the other hand, if the controller  45  determines that the cartridge replacement flag is set to “OFF” (S 90 : NO), the controller  45  skips step S 91 . 
     In S 92  the controller  45  determines whether the printer  10  that transmitted the management information is a printer with tanks, i.e., whether the printer  10  has both a mounting case  150  for mounting cartridges  200  and ink tanks  160  corresponding to the cartridges  200 . The controller  45  makes this determination based on the printer ID included in the management information. Here, a printer without tanks designates a printer provided with the mounting case  150  but not the ink tanks  160 . The process of S 93  is an example of the (j) determining of the present disclosure. 
     If the controller  45  determines that the printer  10  is a printer without tanks (S 93 : NO), in S 93  the controller  45  conducts ordering of cartridges  200  according to the conventional method and ends the ordering process. An example of the conventional method is the method described in Japanese Patent Application Publication No. 2017-47537, but the method performed herein is not limited to this conventional method. However, if the controller  45  determines that the printer  10  is a printer with tanks (S 92 : YES), in S 94  the controller  45  determines whether the C_Empty flag included in the management information is set to “ON”. In other words, in S 94  the controller  45  determines whether the cartridge  200  mounted in the printer  10  has run out of ink. If the controller  45  determines that the C_Empty flag is set to “OFF” (S 94 : NO), in S 95  the controller  45  executes an order date/time setting process. 
     In the order date/time setting process of S 95 , the controller  45  sets a date/time for ordering the cartridge  200  on the basis of the management information received from the printer  10 . The order date/time setting process will be described next with reference to  FIG.  11 A . 
     In S 101  at the beginning of the order date/time setting process, the controller  45  acquires a cartridge-empty residual percentage (hereinafter referred to as “CTG-empty residual percentage,” where “CTG” stands for “cartridge”) on the basis of the type information for the cartridge  200  included in the management information received in S 90 . The CTG-empty residual percentage is the total residual percentage immediately after the cartridge  200  runs out of ink. In the present embodiment, the cartridge management list (described later) storing correlations between type information for cartridges  200  and CTG-empty residual percentages is stored in the storage unit  42  in advance. A table storing correlations between type information for cartridges  200  and CTG-empty residual percentages may be stored in the storage unit  42  in advance. 
     The controller  45  acquires the CTG-empty residual percentage by reading a CTG-empty residual percentage from the cartridge management list stored in the storage unit  42  that corresponds to the type information included in the management information. Note that the CTG-empty residual percentage may be included in the management information transmitted from the printer  10 . In other words, the printer  10  may transmit management information to the information collection server  40  in S 81  that includes the CTG-empty residual percentage, and the controller  45  may acquire the CTG-empty residual percentage from the management information. 
     In S 102  the controller  45  associates the total residual percentage included in the management information and the CTG-empty residual percentage acquired in S 101  with the date/time of acquisition (hereinafter called “acquisition date/time”), i.e., the date/time outputted by the clock  48  when the management information including the residual quantity information was acquired, and stores the associated data in the storage unit  42  as a record in the residual quantity management list illustrated in  FIG.  13 A . A residual quantity management list is created for the cartridge  200  of each color provided in each printer  10 . Each residual quantity management list is identified by a printer ID and a color ID, for example. The process of S 102  is an example of the (b) storing of the present disclosure. The acquisition date/time is an example of the acquisition date of the present disclosure. Note that the controller  45  may store the total residual percentage and the CTG-empty residual percentage in the residual quantity management list in association with a date of acquisition that does not include the time of acquisition rather than the acquisition date/time. 
     The residual quantity management list has a record for each acquisition date/time, with each record including a plurality of data items. The data items include the acquisition date/time, the total residual percentage, the total residual quantity, the cartridge residual quantity, the tank residual quantity, an order flag, a replacement count, and the like. Note that the residual quantity management list may include items other than those given in this example. 
     The item “acquisition date/time” is the date/time at which the management information was acquired. The item “total residual percentage” is the total residual percentage included in the management information. The item “total residual quantity” is a value indicating the tank residual quantity of ink accommodated in the cartridge  200  and ink tank  160  of the printer  10 . The total residual quantity may be included in the management information together with the total residual percentage, or the controller  45  may calculate the total residual quantity from the printer ID, total residual percentage, and model name included in the management information. The item “cartridge residual quantity” is the cartridge residual quantity included in the management information. The item “tank residual quantity” is the tank residual quantity included in the management information. The item “order flag” is a value set to either “ON” or “OFF”. The order flag is set to “ON” when a new cartridge  200  is ordered and is set to “OFF” when the old cartridge  200  in the printer  10  is replaced. The item “replacement count” is a value indicating the number of times the cartridge  200  has been replaced in the printer  10  to date. 
     Each record in the residual quantity management list stores total residual percentages transmitted by the printer  10  at different dates/times in association with their acquisition dates/times. Upon acquiring new management information, the controller  45  adds a new record to the residual quantity management list. 
     In S 103  of the process in  FIG.  11 A , the controller  45  determines whether the residual quantity management list contains two or more records for the same cartridge  200  indicating a total residual percentage less than 100%. Specifically, the controller  45  determines whether the residual quantity management list contains two or more records corresponding to the same ID of the cartridge  200  and including the same value of the replacement count. If the controller  45  determines there are not two or more such records for the same cartridge  200  (S 103 : NO), the controller  45  ends the order date/time setting process. However, if the controller  45  determines that there are two or more such records (S 103 : YES), in S 104  the controller  45  sets a linear function based on dates/times and total residual percentages. The method of setting the linear function will be described next with reference to  FIG.  12 A .  FIG.  12 A  illustrates a graph whose horizontal axis (X-axis) represents date/time and whose vertical axis (Y-axis) represents total residual percentage. 
     The controller  45  sets an initial record at which the total residual percentage has dropped below 100% according to the items “total residual percentage” and “acquisition date/time” in the residual quantity management list. The controller  45  acquires the acquisition date/time T 1  and the total residual percentage P 1  for the record set above from the residual quantity management list. The controller  45  also sets a most recent record according to the item “acquisition date/time” in the residual quantity management list. The controller  45  acquires the acquisition date/time T 2  and the total residual percentage P 2  for the most recent record from the residual quantity management list. Here, the acquisition date/time T 2  is a date/time at which management information including data items in the most recent record was acquired, and is also called a “current date/time”. 
     Next, the controller  45  sets a straight line passing through point (T 1 , P 1 ) and point (T 2 , P 2 ) having the slope (P 2 −P 1 )/(T 2 −T 1 ) as the linear function. Note that the controller  45  may set the linear function to a line passing through points specified by any two records with a total residual percentage less than 100%. 
     After setting the linear function in S 104  of  FIG.  11 A , in S 105  the controller  45  estimates a cartridge-empty date/time (hereinafter referred to as “CTG-empty date/time,” where “CTG” stands for “cartridge”) and an out-of-ink date/time. The CTG-empty date/time indicates the date/time at which the cartridge  200  will run out of ink. The out-of-ink date/time indicates the date/time at which neither the cartridge  200  nor the ink tank  160  will contain any ink. 
     In S 106  the controller  45  sets an estimated arrival date/time of a cartridge  200  based on the estimated CTG-empty date/time and out-of-ink date/time. In S 107  the controller  45  sets an order date/time based on the estimated arrival date/time. Here, the estimated arrival date/time indicates the date/time at which arrival of a new cartridge  200  is desired. The order date/time indicates the date/time to order the cartridge  200 . The estimated arrival date/time is an example of the first calendar date of the present disclosure. The CTG-empty date/time is an example of the second calendar date of the present disclosure. The out-of-ink date/time is an example of the third calendar date of the present disclosure. The order date/time is an example of the order date of the present disclosure. Note that the CTG-empty date/time, the out-of-ink date/time, the estimated arrival date/time, and the order date/time may all indicate a date that does not include a time. 
     Here, steps S 105 , S 106 , and S 107  will be described in greater detail with reference to  FIG.  12 A . In S 105  the controller  45  estimates the CTG-empty date/time indicating the date/time at which the total residual percentage becomes the CTG-empty residual percentage according to the linear function set in S 104 . In other words, the controller  45  estimates the date/time at which the cartridge  200  will become empty and sets the CTG-empty date and time to this date/time. Next, in S 105  the controller  45  estimates the out-of-ink date/time indicating the date/time at which the total residual percentage becomes zero according to the linear function set in S 104 . In other words, the controller  45  estimates the date/time at which both the cartridge  200  and ink tank  160  will run out of ink and sets the out-of-ink date/time to this date/time. In S 106  the controller  45  sets the middle date/time of a time span between the CTG-empty date/time and the out-of-ink date/time as the estimated arrival date/time on which the cartridge  200  are desired to reach the user and stores this estimated arrival date/time in the storage unit  42 . 
     The estimated arrival date/time is set to the middle date/time of the time span between the CTG-empty date/time and the out-of-ink date/time to ensure that, even if the cartridge  200  does not arrive exactly on the estimated arrival date/time, the user will receive the new cartridge  200  sometime after the cartridge  200  runs out of ink and before the cartridge  200  and ink tank  160  both run out of ink. 
     Note also that the linear function is set using the initial record at which the total residual percentage became less than 100% and the most recent record in order to suppress a drop in precision for estimating the CTG-empty date/time and out-of-ink date/time. A drop in the precision for estimating the CTG-empty date/time and out-of-ink date/time signifies a larger difference between the estimated out-of-ink date/time and the actual date/time that the printer  10  runs out of ink and a larger difference between the estimated CTG-empty date/time and the actual date/time that the cartridge  200  runs out of ink. 
     More specifically, the printer  10  transmits 100% to the information collection server  40  as the total residual percentage when the total residual percentage exceeds 100%, as described above. Therefore, the total residual percentage may exceed 100% on the printer  10  when the information collection server  40  stores 100% as the total residual percentage. Consequently, if the controller  45  were to set a linear function based on a total residual percentage of 100% despite the total residual percentage exceeding 100%, the precision in estimating the out-of-ink date/time and CTG-empty date/time may be lower. Thus, setting the linear function using records whose total residual percentage is under 100% can likely suppress a drop in precision for estimating the out-of-ink date/time and CTG-empty date/time. 
     As described above, the residual ink quantity specified by the cartridge residual quantity and the residual ink quantity specified by the tank residual quantity include error with respect to the actual quantity of ink accommodated in the cartridge  200  and the actual quantity of ink accommodated in the ink tank  160 . This error can accumulate as the quantity of ink discharged by the recording head  21  increases. Therefore, it is highly probable that the total residual percentage in the initial record for which the total residual percentage is less than 100% will have less error than the total residual percentage in records transmitted after this initial record. Hence, by using the initial record having a total residual percentage under 100%, it may be possible to suppress a drop in precision for setting the estimated arrival date/time. 
     Further, since the amount of ink usage varies daily, using the total residual percentage of the most recent record likely can suppress a drop in setting precision for the estimated arrival date/time better than using the total residual percentage of an older record. 
     In S 107  the controller  45  sets the order date/time for ordering a new cartridge  200  to a date/time earlier than the set estimated arrival date/time by a delivery lead time (three days, for example). The delivery lead time is the expected amount of time after a new cartridge  200  has been ordered for the cartridge  200  to reach the address included in the user information stored on the information collection server  40 . The delivery lead time is stored in the storage unit  42  in advance, and is an example of the first period of time of the present disclosure. The address is stored in the cartridge management list in association with the color ID for the cartridge  200  and the printer ID of the printer  10  in advance. 
     In S 109  the controller  45  stores the order date/time in the cartridge management list in  FIG.  13 B  and subsequently ends the order date/time setting process. Note that step S 108  depicted with dashed lines in  FIG.  11 A  describes a process executed in the second and third embodiments and is not used in the present embodiment. 
     The cartridge management list illustrated in  FIG.  13 B  enables the information collection server  40  to oversee a plurality of printers  10 . The administrator of the information collection server  40  uses the cartridge management list to manage or monitor the ordering of cartridges  200 , for example. 
     The cartridge management list stores a record for the cartridge  200  of each color in each printer  10 . Each record has a plurality of items that include “printer ID,” “model name,” “color ID,” “order date/time,” “order flag,” “replacement count,” “CTG-empty residual percentage,” “address,” and the like. Note that the cartridge management list may include items other than those given in this example. 
     The item “printer ID” uniquely identifies each printer  10 , and may be a MAC address or a serial number, for example. The item “model name” specifies the model name of the printer  10 . The item “color ID” identifies color of ink accommodated in each cartridge  200 . The item “order date/time” specifies the order date/time set in S 107 . The controller  45  sets an order date/time every time management information is received from a printer  10  and updates the item “order date/time” in the cartridge management list with the latest order date/time. The items “order flag” and “replacement count” are identical to the same items in the residual quantity management list. The item “CTG-empty residual percentage” specifies the CTG-empty residual percentage acquired in S 101 . The item “address” specifies the name and address to which new cartridges  200  will be delivered. The information stored in the item “address” is an example of the destination information of the present disclosure. 
     After setting an order date/time in S 95  of  FIG.  10   , or when the controller  45  determines in S 89  that management information was not received (S 89 : NO), in S 96  the controller  45  determines whether it is a fixed time, such as 10:00 a.m. or 12:00 p.m. When it is not the fixed time, the controller  45  ends the ordering process. However, when it is the fixed time, in S 97  the controller  45  determines whether the current date/time has reached the order date/time. 
     Specifically, in the present embodiment, the controller  45  determines every day at the fixed time whether the current date/time has reached the order date/time in any of the records stored in the cartridge management list. If the current date/time has not yet reached the order date/time in any of records (S 97 : NO), the controller  45  ends the ordering process. However, when the current date/time reach the order date/time for any one or more records (S 97 : YES), in S 98  the controller  45  determines whether the order flag is set to “OFF” in the record(s). In other words, the controller  45  determines in S 98  whether a new cartridge  200  has already been ordered for replacement with the cartridge  200  corresponding to the record(s) determined to have an order date/time matching the current date/time. 
     When the order flag is set to “ON” (S 98 : NO), the controller  45  ends the ordering process. In other words, when a new cartridge  200  has already been ordered for the corresponding cartridge  200 , the controller  45  ends the ordering process without ordering another cartridge  200 . However, when the controller  45  determines that the order flag is set to “OFF” (S 98 : YES), in S 99  the controller  45  transmits an order command to the shipping server  50 . More specifically, the controller  45  determines every day at a fixed time, such as 10:00 a.m. or 12:00 p.m., whether the current date/time has reached the order date/time in any of the records, and transmits an order command to the shipping server  50  for ordering a cartridge  200  in each record determined to have an order date/time matching the current date/time. The order command includes information identifying the type of the cartridge  200  (type information), such as a part number, the destination for delivering the cartridge  200  (such as addressee information and address information), and the like. Upon receiving an order command, the shipping server  50  arranges the shipment of a cartridge  200  having the part number (type information) included in the order command to the destination included in the order command. The process of step S 99  in which the information collection server  40  transmits an order command is an example of the (d) transmitting of the present disclosure. 
     On the other hand, if the controller  45  determines in S 94  that the C_Empty flag is “ON” (S 94 : YES), the controller  45  skips steps S 95  through S 97  and executes steps S 98  and S 99  described above. In other words, when the cartridge  200  has run out of ink (S 94 : YES) and a new cartridge  200  has not yet been ordered (S 98 : YES), the controller  45  immediately places an order for a new cartridge  200 , without setting an order date/time and waiting the fixed time. However, the controller  45  may transmit a command after waiting the fixed time when the C_Empty flag is “ON” (S 94 : YES) and the order flag is “OFF” (S 98 : YES). 
     After transmitting the order command in S 99 , in S 100  the controller  45  sets item “order flag” in the corresponding record to “ON” in both the residual quantity management list and the cartridge management list and increments the value in item “replacement count” in the cartridge management list by one. Subsequently, the controller  45  ends the ordering process. 
     Effects of the First Embodiment 
     In the first embodiment, the recording head  21  prints using ink supplied to ink tanks  160  from cartridges  200  mounted in the mounting case  150 . Accordingly, as long as ink remains in the ink tanks  160 , the recording head  21  can continue printing on sheets using residual ink in the ink tanks  160 , even when ink no longer remains in the cartridges  200 . For this reason, the controller  130  sets an order condition (order date/time) for transmitting an order command to order a new cartridge  200  so that the new cartridge  200  will be mounted in the mounting case  150  when ink no longer remains in the currently mounted cartridge  200  but remains in the ink tank  160 . By transmitting an order command when the order date/time has arrived and the order condition has been met, the controller  130  ensures that a new cartridge  200  will reach the user in time for the user to replace the old cartridge  200  when the old cartridge  200  no longer holds ink but ink remains in the ink tank  160 . Thus, since the ink tank  160  still holds ink at the time of cartridge replacement, the controller  130  avoids falling into a situation in which printing is not possible before the cartridge  200  is replaced. Further, since the used cartridge  200  no longer contains ink when the cartridge  200  is replaced, the controller  130  can avoid wasting ink when the cartridge  200  is replaced. 
     In the first embodiment, the estimated arrival date/time is calculated by setting a linear function based on two total residual percentages and their acquisition dates/times. Accordingly, the embodiment requires fewer operations by the CPU  35  to calculate the estimated arrival date/time than when setting a polynomial of degree two or greater or when setting a linear function using standard deviation, thereby facilitating computation of the estimated arrival date/time. 
     In the first embodiment, the estimated arrival date/time is set to the middle date/time of the time span between the CTG-empty date/time and the out-of-ink date/time. Therefore, even if the new cartridge  200  reaches the user earlier or later than expected, the new cartridge  200  can reach the user while ink no longer remains in the old cartridge  200  but remains in the ink tank  160 . 
     In the first embodiment, an order date/time is calculated each time new residual quantity information (total residual percentage) is acquired, thereby improving the precision of the calculated order date/time. Thus, the embodiment improves the probability that the new cartridge  200  will be delivered to the user while the old cartridge  200  is depleted of ink but the ink tank  160  still holds ink. 
     In the first embodiment, the printer  10  transmits total residual percentages no greater than 100% to the information collection server  40 . Accordingly, the information collection server  40  can treat residual percentages inputted from printers that do not possess ink tanks  160  the same as total residual percentages inputted from printers  10  that have ink tanks  160 . Thus, a different information collection server need not be used for each type of printer. In other words, a single information collection server  40  can order cartridges for printers that possess no ink tanks  160  and can order cartridges  200  for printers  10  that possess ink tanks  160 . 
     In the first embodiment, the linear function is set on the basis of records whose total residual percentage is less than 100%. Accordingly, the first embodiment can suppress a drop in precision for estimating the out-of-ink date/time and CTG-empty date/time. 
     When the C_Empty flag included in the management information is set to “ON” in the first embodiment, a new cartridge  200  is ordered without setting an order date/time. Therefore, the first embodiment can increase the probability that the new cartridge  200  will reach the user while the ink tank  160  still contains ink. 
     In the first embodiment, the controller  45  determines whether the printer  10  is a printer with tanks, i.e., whether the printer  10  is provided with ink tanks  160 . The controller  45  executes the order date/time setting process illustrated in  FIG.  10    when determining that the printer  10  is a printer with tanks. Hence, the first embodiment enables the information collection server  40  to order cartridges for printers without ink tanks  160  and to order cartridges  200  for printers  10  with ink tanks  160 . 
     Second Embodiment 
     The second embodiment describes a case in which the order date/time is modified on the basis of the slope of the linear function set in step S 104  of  FIG.  11 A . 
     In S 108  illustrated in  FIG.  11 A , the controller  45  of the information collection server  40  executes an order date/time modification process after setting the order date/time in S 107 . This process will be described next with reference to  FIG.  11 B . 
     In S 111  of  FIG.  11 B , the controller  45  determines whether the absolute value of the slope of the linear function set in S 104  is greater than or equal to a threshold slope. The absolute value of the slope of the linear function is dependent on the rate of ink consumption on the printer  10 . In other words, the absolute value of slope increases as the rate of ink consumption increases and decreases as the rate of ink consumption decreases. The threshold slope is stored in the storage unit  42  in advance. The threshold slope is an example of the threshold slope of the present disclosure. 
     When the controller  45  determines that the absolute value of the slope of the linear function is less than the threshold slope (S 111 : NO), the controller  45  ends the order date/time modification process. Returning to the order date/time setting process of  FIG.  11 A , in S 109  the controller  45  stores the order date/time set in S 107  in the item order date/time” of the cartridge management list illustrated in  FIG.  13 B . 
     However, when the controller  45  determines that the absolute value of the slope is greater than or equal to the threshold slope (S 111 : YES), in S 112  the controller  45  modifies the order date/time set in S 107  of the order date/time setting process illustrated in  FIG.  11 A . This modification step will be described in greater detail with reference to  FIG.  14 A . 
       FIG.  14 A  illustrates a linear function in which the absolute value of slope is greater than or equal to the threshold slope. In S 112  the controller  45  modifies the order date/time set in S 107  of  FIG.  11 A  to a date/time earlier by a first safety period of time (two days, for example). The first safety period of time is stored in the storage unit  42  in advance. Subsequently, the controller  45  ends the order date/time modification process. Returning to the order date/time setting process of  FIG.  11 A , in S 109  the controller  45  stores the modified order date/time in the item “order date/time” of the cartridge management list illustrated in  FIG.  13 B . Hence, the controller  45  modifies the order date/time stored in the cartridge management list. The process of S 112  to modify the order date/time is an example of the (f) modifying of the present disclosure. The first safety period of time is an example of the second period of time of the present disclosure. The modified order date/time is an example of the order date of the present disclosure. 
     Effects of the Second Embodiment 
     As described above, the significance of the absolute value of slope for the linear function being greater than the threshold value is that the rate of ink consumption is high. When the rate of ink consumption is high, there is a greater chance that the ink stored in the ink tank  160  will be depleted before the new cartridge  200  reaches the user. In the second embodiment, the controller  45  orders a new cartridge  200  on a date/time earlier than the order date/time set in S 107  by the first safety period when the absolute value of the slope for the linear function is greater than or equal to the threshold slope. In this way, the second embodiment can suppress the potential for the ink tank  160  running out of ink before the new cartridge  200  reaches the user. 
     Third Embodiment 
     The second embodiment describes a case in which the rate of ink consumption is determined on the basis of the absolute value of the slope of the linear function. In the third embodiment, the rate of ink consumption is determined on the basis of the time interval between the CTG empty date/time and out-of-ink date/time estimated in step S 105  of  FIG.  11 A , and the order date/time is modified on the basis of the determined rate of ink consumption. 
     In S 108  of  FIG.  11 A , the controller  45  of the information collection server  40  executes an order date/time modification process after setting the order date/time in S 107 . This process will be described in greater detail with reference to  FIG.  11 C . 
     In S 113  of  FIG.  11 C , the controller  45  calculates the period of time between the CTG empty date/time and the out-of-ink date/time. The period of time between the CTG empty date/time and the out-of-ink date/time is dependent on the rate of ink consumption on the printer  10 . That is, the period of time between the CTG empty date/time and the out-of-ink date/time is shorter when the rate of ink consumption is faster and longer when the rate of ink consumption is slower. 
     In S 114  the controller  45  determines whether the period of time calculated in S 113  is less than a threshold period of time. The threshold period of time is stored in the storage unit  42  in advance. If the controller  45  determines that the calculated period of time is greater than or equal to the threshold period of time (S 114 : NO), the controller  45  skips S 115  and ends the order date/time modification process. Returning to the order date/time setting process of  FIG.  11 A , in S 109  the controller  45  stores the order date/time set in S 107  in the item order date/time” of the cartridge management list illustrated in  FIG.  13 B . 
     However, if the controller  45  determines that the calculated period of time is less than the threshold period of time (S 114 : YES), in S 115  the controller  45  modifies the order date/time set in S 107  of  FIG.  11 A . The modification process in step S 115  will be described in greater detail with reference to  FIG.  14 B . The threshold period of time is an example of the threshold interval of the present disclosure. 
       FIG.  14 B  illustrates a linear function in which the calculated period of time is less than the threshold period of time. In S 115  the controller  45  modifies the order date/time set in S 107  to an earlier date/time by the first safety period of time (two days, for example). The first safety period of time is stored in the storage unit  42  in advance. Subsequently, the controller  45  ends the order date/time modification process. Returning to the order date/time setting process of  FIG.  11 A , in S 109  the controller  45  stores the modified order date/time under item “order date/time” in the cartridge management list of  FIG.  13 B . In this way, the controller  45  updates the order date/time. The process of S 112  to modify the order date/time is an example of the (f) modifying of the present disclosure. The first safety period of time is an example of the second period of time of the present disclosure. The modified order date/time is an example of the order date of the present disclosure. 
     Effects of the Third Embodiment 
     In the above description, the significance of the period of time between the CTG-empty date/time and the out-of-ink date/time being less than the threshold period of time is that the rate of ink consumption is high. When the rate of ink consumption is high, there is increased probability that the ink tank  160  will become depleted of ink prior to the new cartridge  200  reaching the user. In the third embodiment, when the period of time between the CTG-empty date/time and the out-of-ink date/time is less than the threshold period of time, the new cartridge  200  is ordered on a date/time earlier than the order date/time set in S 107  by the first safety period of time. Accordingly, the third embodiment can reduce the chance of the ink tank  160  running out of ink before the new cartridge  200  reaches the user. 
     While the description has been made in detail with reference to specific embodiments thereof, it would be apparent to those skilled in the art that many modifications and variations may be made thereto. Some variations of the embodiments are given below. 
     &lt;First Modification&gt; 
     In the example of the embodiments, the estimated arrival date/time is set to the middle date/time of a time span between the CTG-empty date/time and the out-of-ink date/time. In this modification, another example for setting the estimated arrival date/time will be described with reference to  FIG.  12 B . 
     In the first modification, the controller  45  of the information collection server  40  sets a reference percentage based on the cartridge-empty residual percentage acquired in S 101  of  FIG.  11 A . The reference percentage is used as a reference for determinations. For example, the controller  45  sets the reference percentage to half the CTG-empty residual percentage. The controller  45  then determines as the estimated arrival date/time the date/time at which the total residual percentage becomes the reference percentage according to the linear function set in S 104  of  FIG.  11 A . Thereafter, as described in the embodiments, the controller  45  stores the estimated arrival date/time in the storage unit  42 , sets the order date/time to a date/time earlier than the estimated arrival date/time by the delivery lead time, and stores this order date/time in the item “order date/time” in the cartridge management list of  FIG.  13 B . Note that the reference percentage may be set to a value smaller than the CTG-empty residual percentage by a prescribed value stored in the storage unit  42 . The estimated arrival date/time is an example of the first calendar date of the present disclosure. The order date/time is an example of the order date of the present disclosure. 
     &lt;Effects of the First Modification&gt; 
     Despite setting the estimated arrival date/time on the basis of the CTG-empty residual percentage, the first modification can set the estimated arrival date/time to a date/time at which it is highly probable that the cartridge  200  will be out of ink while the ink tank  160  still contains ink. In other words, a new cartridge  200  can be ordered so that the cartridge  200  will no longer contain ink while the ink tank  160  will still have residual ink on the day that the new cartridge  200  arrives. 
     &lt;Second Modification&gt; 
     The first embodiment describes an example in which the CTG-empty date/time and the out-of-ink date/time are estimated and the estimated arrival date/time is set using the estimated CTG-empty date/time and out-of-ink date/time. In this modification, an example in which the estimated arrival date/time is set without estimating a CTG-empty date/time will be described with reference to  FIG.  15 A . 
     The controller  45  of the information collection server  40  estimates an out-of-ink date/time according to a linear function set in S 104  of  FIG.  11 A . The out-of-ink date/time is the date/time at which the total residual percentage will become zero. Next, the controller  45  sets an estimated arrival date/time to a date/time earlier than the out-of-ink date/time estimated in S 104  by a second safety period of time. The second safety period of time is the maximum amount of delay anticipated for delivery of a new cartridge  200  to the user, and is stored in the storage unit  42  in advance. The estimated arrival date/time is an example of the first calendar date of the present disclosure. 
     Subsequently, as in the first embodiment described above, the controller  45  stores the estimated arrival date/time in the storage unit  42 , sets the order date/time to a date/time earlier than the estimated arrival date/time by the delivery lead time, and stores this order date/time in the item “order date/time” of the cartridge management list (see  FIG.  13 B ). The order date/time is an example of the order date of the present disclosure. 
     &lt;Effects of the Second Modification&gt; 
     Since the second safety period of time is set to a maximum anticipated delay for a new cartridge  200  when delivery of the new cartridge  200  to the user is delayed and the estimated arrival date/time is set to the date/time earlier than the out-of-ink date/time by this second safety period of time, the new cartridge  200  ordered according to the order date/time set above will at least reach the user before the printer  10  runs out of ink, even if delivery of the cartridge  200  is delayed. Therefore, the second modification reduces the chance that the user will be unable to continue printing. 
     &lt;Third Modification&gt; 
     The first embodiment describes an example in which the CTG-empty date/time and the out-of-ink date/time are estimated and the estimated arrival date/time is set using the estimated CTG-empty date/time and out-of-ink date/time. In this modification, an example in which the estimated arrival date/time is set without estimating an out-of-ink date/time will be described with reference to  FIG.  15 B . 
     The controller  45  of the information collection server  40  estimates the CTG-empty date/time according to the linear function set in S 104  of  FIG.  11 A . The CTG-empty date/time is the date/time at which the total residual percentage becomes the CTG-empty residual percentage. Next, the controller  45  sets the estimated arrival date/time to a date/time later than the CTG-empty date/time by a third safety period of time (two days, for example). The third safety period of time is stored in the storage unit  42  in advance. The third safety period of time is set to a length of time equivalent to the earliest possible period of time that the new cartridge  200  could be delivered after ordering, assuming an earlier date/time than the estimated arrival date/time. The estimated arrival date/time is an example of the first calendar date of the present disclosure. 
     Subsequently, as in the first embodiment described above, the controller  45  stores the estimated arrival date/time in the storage unit  42 , sets the order date/time to a date/time earlier than the estimated arrival date/time by the delivery lead time, and stores this date/time under the item “order date/time” of the cartridge management list illustrated in  FIG.  13 B . 
     &lt;Effects of the Third Modification&gt; 
     Since the third safety period of time is set to a length of time equivalent to the earliest possible delivery time should the new cartridge  200  be delivered earlier than the estimated arrival date/time and the estimated arrival date/time is set to the date/time later than the CTG-empty date/time by this third safety period of time, the new cartridge  200  will at least reach the user after all ink in the cartridge  200  has been consumed, despite the cartridge  200  arriving early. Therefore, the third modification reduces the chance that ink will be wasted if ink still remains in the old cartridge  200  when the user replaces the old cartridge  200  with the new cartridge  200 . 
     &lt;Fourth Modification&gt; 
     The first embodiment describes an example of setting a linear function based on total residual percentages and their acquisition dates/times and using this linear function to set an estimated arrival date/time and an order date/time. This modification will describe an example of setting a linear function based on cartridge residual percentages and using this linear function to set the estimated arrival date/time and the order date/time. 
     In the fourth modification, the controller  130  of the printer  10  executes the management information transmission process illustrated in  FIGS.  16 A and  16 B  in place of the process illustrated in  FIGS.  9 A and  9 B . 
     In the management information transmission process illustrated in  FIGS.  16 A and  16 B , the controller  130  calculates a cartridge residual percentage using the cartridge residual quantity set in one of the updating processes illustrated in  FIGS.  8 A through  8 D , and transmits management information to the information collection server  40  that includes this cartridge residual percentage. In the following description, steps identical to those in the first embodiment are designated with the same step numbers to avoid duplicating description. All steps other than those described in this modification are identical to those described in the first embodiment. 
     As in the first embodiment, when the controller  130  of the printer  10  determines that the current time matches the transmission time (S 61 : YES), in S 62  the controller  130  checks the value of the C_Empty flag, as described in S 62  of the first embodiment. If the controller  130  determines that the C_Empty flag is set to “ON” (S 62 : YES), in S 121  the controller  130  sets the cartridge residual percentage to zero. 
     However, if the controller  130  determines that the C_Empty flag is set to “OFF” (S 62 : NO), in S 122  the controller  130  reads the initial cartridge residual quantity and the initial tank residual quantity from the EEPROM  51 , as described in the first embodiment, and also reads a constant C from the EEPROM  51 . The constant C will be described later. 
     After S 122 , the controller  130  executes the process from S 64  to S 68  that is identical to the first embodiment. Following S 68 , in S 123  the controller  130  calculates a cartridge residual percentage (%) by dividing the new cartridge residual quantity set in S 66  by the constant C read in S 122  and multiplying the result by 100. 
     In S 124  the controller  130  determines whether the cartridge residual percentage calculated in S 123  exceeds 100%. A case in which the cartridge residual percentage exceeds 100% will be described next in greater detail. 
     The constant C is a value indicating the quantity of ink accommodated in a new cartridge  200  when the difference in hydraulic head between the ink accommodated in the new cartridge  20  and ink accommodated in the ink tank  160  becomes negligible after the new cartridge  200  accommodating ink of an initial fill quantity was mounted in the mounting case  150  while the S_Empty flag was set to “ON”. Hence, the cartridge residual quantity is the value exceeding the constant C when a new cartridge  200  accommodating ink of the initial fill quantity is mounted in the mounting case  150  while ink remains in the ink tank  160 . When the cartridge residual quantity exceeds the constant C, the cartridge residual percentage calculated by dividing the cartridge residual quantity by the constant C and multiplying by 100 will exceed 100%. In other words, when a new cartridge  200  accommodating ink at the initial fill quantity is mounted in the mounting case  150  while ink remains in the ink tank  160 , the cartridge residual percentage is greater than 100%. 
     Note that the constant C is the same value as the cartridge residual quantity calculated when a cartridge  200  accommodating ink at the initial fill quantity is mounted in the mounting case  150  while the S_Empty flag is set to “ON” (see S 35  in  FIG.  8 A ). 
     If the controller  130  determines in S 124  that the cartridge residual percentage exceeds 100% (S 124 : YES), in S 125  the controller  130  changes the cartridge residual percentage to 100%. However, if the controller  130  determines that the cartridge residual percentage does not exceed 100% (S 124 : NO), the controller  130  skips S 125 . 
     The controller  130  changes a cartridge residual percentage to 100% when the cartridge residual percentage exceeds 100% to ensure consistency with printers that do not transmit cartridge residual percentages greater than 100%. A printer that does not transmit a cartridge residual percentage exceeding 100% signifies a printer provided with the mounting case  150  but not the ink tanks  160 . Printers having a mounting case  150  but no ink tanks  160  transmit a value obtained by dividing the current residual quantity by the initial fill quantity in the cartridge and multiplying the result by 100 as the residual percentage. In other words, a printer that has a mounting case  150  but no ink tanks  160  transmits a residual percentage of 100% or less. Since the printer  10  modifies a cartridge residual percentage exceeding 100% to 100%, the printer  10  can ensure consistency with printers having a mounting case  150  but no ink tanks  160 . In other words, the printer  10  can transmit a cartridge residual percentage to an information collection server  40  incapable of processing residual percentages over 100% and direct the information collection server  40  to process this data. 
     In S 126  the controller  130  stores the cartridge residual percentage calculated in S 123 , the cartridge residual percentage adjusted to 100% in S 125 , or the cartridge residual percentage set to zero in S 121  in the RAM  52 . 
     In S 127  the controller  130  reads the value of the C_Empty flag, the device information, and the value of the cartridge replacement flag from the EEPROM  51 , the cartridge residual quantity and the cartridge residual percentage from the RAM  52 , and the type information for the cartridge  200  from the IC chip  34 . In S 128  the controller  130  generates management information that includes the value of the C_Empty flag, the cartridge residual quantity, the cartridge residual percentage, the device information, the type information of the cartridge  200 , and the value of the cartridge replacement flag. The cartridge residual percentage included in the management information is an example of the index value of the present disclosure. 
     In S 81  the controller  130  transmits the management information generated in S 128  to the information collection server  40 , as in the first embodiment. Also as in the first embodiment, the controller  130  sets the cartridge replacement flag to “OFF” in S 82  and subsequently ends the management information transmission process. 
     As in the first embodiment, the information collection server  40  receives the management information transmitted from the printer  10 . Upon receiving the management information, the controller  45  of the information collection server  40  executes, as the process in S 96  of  FIG.  10   , the order date/time setting process illustrated in  FIG.  18 A  in place of the process illustrated in  FIG.  11 A . The order date/time setting process of  FIG.  18 A  will be described next, wherein the steps identical to those in the process described in the first embodiment ( FIG.  11 A ) are designated with the same step numbers to avoid duplicating description. 
     At the beginning of the order date/time setting process of  FIG.  18 A , the controller  45  of the information collection server  40  executes the same steps S 102  and S 103  described in the first embodiment. Note that the residual quantity management list in which management information is stored in S 102  is provided with the item “cartridge residual percentage” in place of the items “total residual percentage,” “total residual quantity,” and “tank residual quantity.” 
     If the controller  45  determines in S 103  that the residual quantity management list contains two or more records for the same cartridge  200  indicating a cartridge residual percentage less than 100% (S 103 : YES), in S 131  the controller  45  sets a linear function based on the dates/times and cartridge residual percentages in these records. 
     The method of setting the linear function will be described next in greater detail with reference to  FIG.  19 A .  FIG.  19 A  illustrates a graph whose horizontal axis (X-axis) represents date/time and whose vertical axis (Y-axis) represents cartridge residual percentage. 
     The controller  45  sets an initial record at which the cartridge residual percentage has dropped below 100% according to the items “cartridge residual percentage” and “acquisition date/time” in the residual quantity management list. The controller  45  acquires the acquisition date/time T 1  and cartridge residual percentage P 1  for the initial record set above from the residual quantity management list. The controller  45  also sets a most recent record according to the item “acquisition date/time” in the residual quantity management list. The controller  45  acquires the acquisition date/time T 2  and the cartridge residual percentage P 2  for the most recent record from the residual quantity management list. Here, the acquisition date/time T 2  is a date/time at which management information including data items in the most recent record was acquired, and is also called a “current date/time”. 
     In S 131  the controller  45  sets a straight line passing through point (T 1 , P 1 ) and point (T 2 , P 2 ) having the slope (P 2 −P 1 )/(T 2 −T 1 ) as the linear function. Note that the controller  45  may set the linear function to a line passing through points specified by any two records with a cartridge residual percentage less than 100%. 
     After setting the linear function in S 131  of  FIG.  18 A , in S 132  the controller  45  estimates a CTG-empty date/time. In S 133  the controller  45  sets an estimated arrival date/time from the CTG-empty date/time estimated in S 132  and stores the estimated arrival date/time in the storage unit  42 . In S 134  the controller  45  sets an order date/time indicating the date/time that the cartridge  200  is to be ordered on the basis of the estimated arrival date/time. This process will be described in greater detail with reference to  FIG.  19 A . 
     The controller  45  estimates the CTG-empty date/time indicating when the cartridge residual percentage will become zero according to the linear function set in S 131 . In other words, the controller  45  sets the date/time at which the cartridge  200  will become empty as the CTG-empty date/time. Next, the controller  45  sets the estimated arrival date/time to be the date/time later than the CTG-empty date/time by a third safety period of time. The third safety period of time is set to a length of time equivalent to the earliest possible period of time that the new cartridge  200  could be delivered after ordering, assuming an earlier date/time than the estimated arrival date/time, and is stored in the storage unit  42  in advance. The estimated arrival date/time is an example of the first calendar date of the present disclosure. 
     In S 134  the controller  45  sets the order date/time to a date/time earlier than the estimated arrival date/time by the delivery lead time, and in S 135  stores this order date/time under the item “order date/time” in the cartridge management list. The order date/time is an example of the order date of the present disclosure. 
     &lt;Effects of the Fourth Modification&gt; 
     In the fourth modification, the controller  45  sets a linear function based on acquisition dates/times and cartridge residual percentages and according to this linear function sets an estimated arrival date/time at which the cartridge  200  is expected to be out of ink while the ink tank  160  is expected to still contain ink. The controller  45  sets an order date/time indicating the date/time to transmit an order command to a date/time earlier than the estimated arrival date/time by the delivery lead time. Therefore, the new cartridge  200  can be delivered to the user at a time when ink no longer remains in the old cartridge  200  but still remains in the ink tank  160 . Thus, the fourth modification can prevent printing from becoming impossible before the cartridge  200  can be replaced and can prevent ink from being wasted owing to the old cartridge  200  being replaced by the new cartridge  200  while ink still remains in the old cartridge  200 . 
     Further, since the third safety period of time is set to a length of time equivalent to the earliest possible delivery time should the new cartridge  200  be delivered earlier than the estimated arrival date/time and the estimated arrival date/time is set to the date/time later than the CTG-empty date/time by this third safety period of time, the new cartridge  200  at least reaches the user after the existing cartridge  200  becomes depleted of ink, even if the cartridge  200  is delivered to the user faster than expected. Therefore, the fourth modification reduces the chance of ink being wasted owing to the old cartridge  200  being replaced by the new cartridge  200  while ink still remains in the old cartridge  200 . 
     &lt;Fifth Modification&gt; 
     The first embodiment describes an example of setting a linear function based on total residual percentages and their acquisition dates/times and using this linear function to set an estimated arrival date/time and an order date/time. The fifth modification describes an example of setting a linear function based on the tank residual percentages and using this linear function to set the estimated arrival date/time and the order date/time. 
     In the fifth modification, the controller  130  of the printer  10  executes the management information transmission process illustrated in  FIGS.  17 A and  17 B  in place of the process illustrated in  FIGS.  9 A and  9 B . 
     As in the first embodiment, when the controller  130  of the printer  10  determines that the current time matches the transmission time (S 61 : YES), in S 62  the controller  130  checks the value of the C_Empty flag, as described in S 62  of the first embodiment. If the controller  130  determines that the C_Empty flag is set to “OFF” (S 62 : NO), in S 141  the controller  130  reads the initial cartridge residual quantity and initial tank residual quantity from the EEPROM  51 , as described in the first embodiment, and also reads a constant T from the EEPROM  51 . The constant T will be described later. 
     After S 141 , the controller  130  executes the process from S 64  to S 68  that is identical to the first embodiment. Following S 68 , in S 142  the controller  130  calculates a tank residual percentage (%) by dividing the new tank residual quantity set in S 66  by the constant T read in S 141  and multiplying the result by 100. 
     In S 143  the controller  130  determines whether the tank residual percentage calculated in S 142  exceeds 100%. A case in which the tank residual percentage exceeds 100% will be described next in greater detail. 
     The constant T is a value indicating the quantity of ink accommodated in the ink tank  160  when the difference in hydraulic head between ink accommodated in a new cartridge  20  and ink accommodated in the ink tank  160  becomes negligible after the new cartridge  200  accommodating ink of an initial fill quantity was mounted in the mounting case  150  while the S_Empty flag was set to “ON”. Hence, the tank residual quantity is the value exceeding the constant T when a new cartridge  200  accommodating ink of the initial fill quantity is mounted in the mounting case  150  while ink remains in the liquid chamber  171  of the ink tank  160 . When the tank residual quantity exceeds the constant T, the tank residual percentage calculated by dividing the tank residual quantity by the constant T and multiplying by 100 will exceed 100%. 
     Note that the constant T is the same value as the tank residual quantity calculated when a cartridge  200  accommodating ink at the initial fill quantity is mounted in the mounting case  150  while the S_Empty flag is set to “ON” (see S 35  in  FIG.  8 A ). 
     If the controller  130  determines in S 143  that the tank residual percentage calculated in S 142  exceeds 100% (S 143 : YES), in S 144  the controller  130  changes the tank residual percentage to 100%. However, if the controller  130  determines that the tank residual percentage does not exceed 100% (S 143 : NO), the controller  130  skips S 144 . 
     The controller  130  changes the tank residual percentage to 100% when the tank residual percentage exceeds 100% to ensure consistency with printers that do not transmit residual percentages greater than 100%. A printer that does not transmit residual percentages exceeding 100% signifies a printer provided with the mounting case  150  but not the ink tanks  160 . Printers having a mounting case  150  but no ink tanks  160  transmit a value obtained by dividing the current residual quantity by the initial fill quantity in the cartridge and multiplying the result by 100 as the residual percentage. In other words, a printer that has a mounting case  150  but no ink tanks  160  transmits a residual percentage of 100% or less. Since the printer  10  modifies a tank residual percentage exceeding 100% to 100%, the printer  10  can ensure consistency with printers having a mounting case  150  but no ink tanks  160 . In other words, the printer  10  can transmit a tank residual percentage to an information collection server  40  incapable of processing residual percentages over 100% and direct the information collection server  40  to process this data. 
     On the other hand, if the controller  130  determines in S 62  that the C_Empty flag is “ON” (S 62 : YES), in S 145  the controller  130  reads the cartridge residual quantity (first prescribed value=zero), the tank residual quantity (second prescribed value) from the RAM  52 , as in the first embodiment, and reads the constant T from the EEPROM  51 . Subsequently, the controller  130  executes the process from S 73  to S 76  that is identical to the first embodiment. Next, in S 146  the controller  130  calculates the tank residual percentage by executing the same process described above for S 142 . 
     In S 147  the controller  130  stores the tank residual percentage calculated in S 142 , the tank residual percentage adjusted to 100% in S 144 , or the tank residual percentage calculated in S 146  in the RAM  52 . 
     In S 148  the controller  130  reads the value of the C_Empty flag, the device information, and the value of the cartridge replacement flag from the EEPROM  51 , the tank residual percentage from the RAM  52 , and the type information for the cartridge  200  from the IC chip  34 . In S 149  the controller  130  generates management information that includes the value of the C_Empty flag, the device information, the type information for the cartridge  200 , the tank residual percentage, and the value of the cartridge replacement flag. The tank residual percentage included in the management information is an example of the index value of the present disclosure. 
     In S 81  the controller  130  transmits the management information generated in S 149  to the information collection server  40 , as in the first embodiment. Also as in the first embodiment, the controller  130  sets the cartridge replacement flag to “OFF” in S 82  and subsequently ends the management information transmission process. 
     As in the first embodiment, the information collection server  40  receives the management information transmitted from the printer  10 . Upon receiving the management information, the controller  45  of the information collection server  40  executes, as the process in S 96  of  FIG.  10   , the order date/time setting process illustrated in  FIG.  18 B  in place of the process illustrated in  FIG.  11 A . The order date/time setting process of  FIG.  18 B  will be described next, wherein the steps identical to those in the process described in the first embodiment ( FIG.  11 A ) are designated with the same step numbers to avoid duplicating description. 
     At the beginning of the order date/time setting process of  FIG.  18 B , the controller  45  of the information collection server  40  executes the same steps S 101  through S 103  described in the first embodiment. Note that the residual quantity management list in which management information is stored in S 102  is provided with the item “tank residual percentage” in place of the items “total residual percentage,” “total residual quantity,” and “cartridge residual quantity.” 
     If the controller  45  determines in S 103  that the residual quantity management list contains two or more records for the same cartridge  200  indicating a tank residual percentage less than 100% (S 103 : YES), in S 151  the controller  45  sets a linear function based on the dates/times and tank residual percentages in these records. 
     The method of setting the linear function will be described next in greater detail with reference to  FIG.  19 B .  FIG.  19 B  illustrates a graph whose horizontal axis (X-axis) represents date/time and whose vertical axis (Y-axis) represents tank residual percentage. 
     The controller  45  sets an initial record at which the tank residual percentage has dropped below 100% according to the items “tank residual percentage” and “acquisition date/time” in the residual quantity management list. The controller  45  acquires the acquisition date/time T 1  and tank residual percentage P 1  for the initial record set above from the residual quantity management list. The controller  45  also sets a most recent record according to the item “acquisition date/time” in the residual quantity management list. The controller  45  acquires the acquisition date/time T 2  and the tank residual percentage P 2  for the most recent record from the residual quantity management list. Here, the acquisition date/time T 2  is a date/time at which management information including data items in the most recent record was acquired, and is also called a “current date/time”. 
     In S 151  the controller  45  sets a straight line passing through point (T 1 , P 1 ) and point (T 2 , P 2 ) having the slope (P 2 −P 1 )/(T 2 −T 1 ) as the linear function. Note that the controller  45  may set the linear function to a line passing through points specified by any two records having a tank residual percentage less than 100%. 
     After setting the linear function in S 151  of  FIG.  18 B , in S 152  the controller  45  estimates a CTG-empty date/time. In S 153  the controller  45  sets an estimated arrival date/time from the CTG-empty date/time estimated in S 152  and stores the estimated arrival date/time in the storage unit  42 . In S 154  the controller  45  sets an order date/time indicating the date/time that the cartridge  200  is to be ordered on the basis of the estimated arrival date/time. This process will be described in greater detail with reference to  FIG.  19 B . 
     The controller  45  estimates the CTG-empty date/time indicating when the tank residual percentage will become the CTG-empty residual percentage according to the linear function set in S 151 . The CTG-empty residual percentage is a value specifying the residual quantity of ink in the ink tank  160  when the cartridge  200  becomes empty. Hence, the controller  45  estimates the date/time at which the cartridge  200  will become empty and sets this date/time as the CTG-empty date/time. Next, the controller  45  sets the estimated arrival date/time to be the date/time later than the CTG-empty date/time by the third safety period of time. The third safety period of time is set to a length of time equivalent to the earliest possible period of time that the new cartridge  200  could be delivered after ordering, assuming an earlier date/time than the estimated arrival date/time. The estimated arrival date/time is an example of the first calendar date of the present disclosure. 
     In S 154  the controller  45  sets the order date/time to a date/time earlier than the estimated arrival date/time by the delivery lead time, and in S 155  stores this order date/time under the item “order date/time” in the cartridge management list. The order date/time is an example of the order date of the present disclosure. 
     &lt;Effects of the Fifth Modification&gt; 
     In the fifth modification, the controller  45  sets a linear function based on acquisition dates/times and tank residual percentages and according to this linear function sets an estimated arrival date/time at which the cartridge  200  is expected to be out of ink while the ink tank  160  is expected to still contain ink. The controller  45  sets an order date/time indicating the date/time to transmit an order command to a date/time earlier than the estimated arrival date/time by the delivery lead time. Therefore, the new cartridge  200  can be delivered to the user at a time when ink no longer remains in the old cartridge  200  but still remains in the ink tank  160 . Thus, the fifth modification can prevent printing from becoming impossible before the cartridge  200  can be replaced and can prevent ink from being wasted owing to the old cartridge  200  being replaced by the new cartridge  200  while ink still remains in the old cartridge  200 . 
     Further, since the third safety period of time is set to a length of time equivalent to the earliest possible delivery time should the new cartridge  200  be delivered earlier than the estimated arrival date/time and the estimated arrival date/time is set to the date/time later than the CTG-empty date/time by this third safety period of time, the new cartridge  200  at least reaches the user after the existing cartridge  200  becomes depleted of ink, even if the cartridge  200  is delivered to the user faster than expected. Therefore, the fourth modification reduces the chance of ink being wasted owing to the old cartridge  200  being replaced by the new cartridge  200  while ink still remains in the old cartridge  200 . 
     &lt;Sixth Modification&gt; 
     The first embodiment describes an example in which the information collection server  40  sets an order date/time and transmits an order command to the shipping server  50  when the current time reaches the order date/time. The sixth modification describes an example in which the information collection server  40  transmits an order command to the shipping server  50  when the total residual percentage reaches an order residual percentage (see  FIG.  20 B ). 
     In this modification, the information collection server  40  executes an order condition setting process illustrated in  FIG.  20 A  in place of the order date/time setting process (in S 96  of  FIG.  10   ). Note that all steps other than those described below are identical to those described in the first embodiment for the order date/time setting process illustrated in  FIG.  11 A  and are designated with the same step numbers used in the first embodiment to avoid duplicating description. 
     As in the order date/time setting process described in the first embodiment, the controller  45  of the information collection server  40  begins the order condition setting process by executing steps S 101  through S 104 . In S 161  the controller  45  calculates an order residual percentage by multiplying the absolute value of the slope of the linear function set in S 104  by a delivery lead time and adds the cartridge-empty residual percentage acquired in S 102  to this product. The delivery lead time is stored in the storage unit  42  in advance. In S 162  the controller  45  stores the order residual percentage calculated in S 161  in the cartridge management list stored in the storage unit  42 , and subsequently ends the order condition setting process. Note that the cartridge management list is provided with the item “order residual percentage” in place of the item “order date/time” in this modification. 
     After executing the order condition setting process in place of the order date/time setting process of S 96  illustrated in  FIG.  10   , the controller  45  executes a process in place of step S 97  to determine whether the total residual percentage included in the management information is greater than or equal to the order residual percentage stored in the cartridge management list. 
     The controller  45  ends the ordering process of  FIG.  10    when determining that the total residual percentage in the management information is greater than or equal to the order residual percentage. However, if the controller  45  determines that the total residual percentage is less than the order residual percentage, the controller  45  executes the same process in S 98  through S 100  described in the first embodiment, and subsequently ends the ordering process. 
     &lt;Effects of the Sixth Modification&gt; 
     In the sixth modification, the information collection server  40  can transmit an order command to the shipping server  50  without identifying an order date/time. 
     &lt;Other Variations&gt; 
     The present embodiments describe examples in which the printer  10  transmits management information to the information collection server  40  when the transmission time arrives. However, the printer  10  may transmit management information to the information collection server  40  at prescribed intervals, such as every twenty-four hours or every forty-eight hours. Alternatively, the printer  10  may transmit management information to the information collection server  40  every time a printing operation is performed or every time ink is discharged from the recording head  21 , including during maintenance. The printer  10  may also transmit management information to the information collection server  40  when the information collection server  40  transmits request information to the printer  10  requesting transmission of the management information. In these variations, the controller  130  of the printer  10  executes a process in place of S 61  in the management information transmission process illustrated in  FIGS.  9 A,  16 A, and  17 A  to determine whether a prescribed time interval (twenty-four hours or forty-eight hours) stored in the EEPROM  51  has elapsed, or to determine whether request information has been received from the information collection server  40 . 
     The present embodiments describe examples in which the information collection server  40  collects information from the printer  10  and transmits order commands. However, the controller  130  of the printer  10  may execute the processes performed by the controller  45  of the information collection server  40  in the embodiments. In other words, the controller  130  of the printer  10  may set the linear function, estimated arrival date/time, and order date/time based on the total residual percentages, cartridge residual percentages, and tank residual percentages and transmits the order commands. In such cases, the printer  10  is an example of the control device of the present disclosure; the memory on the IC chip  34 , the ROM  37 , the EEPROM  51 , and the RAM  52  are an example of the memory of the present disclosure. The controller  130  is an example of the controller of the present disclosure. 
     The present embodiments and their modifications present examples for setting linear functions based on the initial record at which a residual percentage is less than 100% and the most recent record. However, the linear function may be set on the basis of three or more records instead, and the linear function may be set on the basis of the standard deviation found for the three or more records. 
     The present embodiments describe cases in which the information collection server  40  sets the order date/time each time management information is received, and updates the item “order date/time” in the cartridge management list at this time. However, the controller  45  of the information collection server  40  may be configured to set the order date/time only once and not to reset this order date/time until an order command has been transmitted. 
     The present embodiments and their modifications describe cases in which the printer  10  transmits a percentage to the information collection server  40 , such as a total residual percentage, cartridge residual percentage, or tank residual percentage. However, the printer  10  may instead transmit only a total residual quantity, cartridge residual quantity, or tank residual quantity to the information collection server  40 . 
     In the present embodiments and their modifications, the printer  10  adjusts the total residual percentage, cartridge residual percentage, and tank residual percentage to 100% when the percentages exceed 100% so that a total residual percentage, cartridge residual percentage, or tank residual percentage no greater than 100% is transmitted to the information collection server  40 . However, the printer  10  may transmit a total residual percentage, cartridge residual percentage, or tank residual percentage exceeding 100% to the information collection server  40 . 
     In the present embodiments, the management information includes a value of a C_Empty flag, and the information collection server  40  transmits an order command to the shipping server  50  without determining whether the order date/time has arrived when the value of the C_Empty flag is set to “ON”. However, the management information need not include a value of a C_Empty flag, and the information collection server  40  may determine whether to transmit an order command based simply on whether the current time has reached the order date/time. 
     In the present embodiments and their modifications, ink is described as an example of the printing agent. However, the printing agent may be toner and is not limited to ink. 
     In the present embodiments and their modifications, ink flows from the cartridges  200  to the corresponding ink tanks  160  owing to a hydraulic head differential. However, the ink may be configured to flow from the cartridges  200  to the ink tanks  160  by gravity or by using a drive source, such as a pump. When a drive source is used, the ink tanks  160  may be disposed on the recording head  21 , for example. 
     In the present embodiments and their modifications, the printer  10  and information collection server  40  are connected to each other through a communication circuit  6 , such as the Internet. However, the printer  10  and information collection server  40  may be connected via a LAN. In this case, the printer ID for the printer  10  may be an IP address.