Patent Publication Number: US-10308030-B2

Title: Image recording apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from Japanese Patent Application No. 2017-072916 filed Mar. 31, 2017. The entire content of the priority application is incorporated herein by reference. 
     TECHNICAL FIELD 
     This disclosure relates to an image recording apparatus. 
     BACKGROUND 
     As an example of an image recording apparatus, a printer is conventionally known that includes a tank in which ink is stored and that ejects, from nozzles, the ink supplied from the tank so as to record an image on a recording sheet. 
     SUMMARY 
     According to one aspect, this specification discloses an image recording apparatus. The image recording apparatus includes a tank, a cap, a filling port sensor, a recorder, an operating interface, a memory, and a controller. The tank is configured to store ink therein. The tank is formed with a filling port for filling ink. The cap is configured to be attached to the filling port so as to close the filling port. The filling port sensor is configured to detect whether the cap is attached to the filling port or detached from the filling port. The recorder is configured to record an image on a recording sheet by using ink supplied from the tank. The operating interface is configured to receive an operation input. The memory is configured to store an ink remaining amount in the tank. The controller is configured to control a recording operation of the recorder. The controller is configured to: in response to determining based on a detection signal of the filling port sensor that the cap is detached from the filling port and is again attached to the filling port, receive a first input through the operating interface, the first input indicating that ink is filled into the tank; and update the ink remaining amount stored in the memory, based on the first input. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments in accordance with this disclosure will be described in detail with reference to the following figures wherein: 
         FIG. 1A  is an external view of an MFP according to an embodiment; 
         FIG. 1B  is an explanatory diagram showing a state where a cap is attached to a filling port of a tank; 
         FIG. 1C  is an explanatory diagram showing a state where the cap is detached from the filling port of the tank and is placed at a cap placement area; 
         FIG. 1D  is an explanatory diagram showing a state where an ink replenishment bottle is inserted in the filling port of the tank; 
         FIG. 2  is a functional block diagram of the MFP in  FIG. 1A ; 
         FIG. 3  is a diagram showing tables stored in an EEPROM; 
         FIG. 4  is a flowchart showing the operation of the MFP in  FIG. 1A ; 
         FIG. 5  is a sub-flowchart of an ink remaining amount estimation confirmation process in  FIG. 4 ; 
         FIG. 6  is a sub-flowchart of an estimated variation amount correction process in  FIG. 5 ; 
         FIG. 7  is a diagram showing a confirmation screen displayed on a display in  FIG. 1A ; and 
         FIG. 8  is a diagram showing a correction screen displayed on the display in  FIG. 1A . 
     
    
    
     DETAILED DESCRIPTION 
     In the printer described above, the ink remaining amount information of the tank that is managed by the printer can be corrected by a user at any time. Hence, for example, the ink remaining amount information is corrected irrespective of an operation of replenishing ink to the tank, and thus an error occurs between the corrected ink remaining amount information and the actual ink remaining amount in the tank, with the result that a failure may occur in the operation of the printer. 
     An example of an object of this disclosure is to prevent the occurrence of an error between the ink remaining amount information of the tank managed by the image recording apparatus and the actual ink remaining amount in the tank. 
     Some aspects of this disclosure will be described while referring to the accompanying drawings 
     [External Configuration of MFP] 
     An MFP  1  shown in  FIG. 1A  is an example of an image recording apparatus, and has an appearance of the shape of a rectangular parallelepiped in which an X direction is a width direction, a Y direction is a front-rear (depth) direction, and a Z direction is an up-down direction. The MFP  1  includes a printer unit (recorder or print engine)  2 , a scanner unit  3 , an operation key (operating interface)  4 , a display  5 , and a control unit  6  (see  FIG. 2 ). 
     The scanner unit  3  reads an image with an image sensing element so as to generate image data. In the printer unit  2 , the generated image data is printed on a recording sheet that is stored within the MFP  1  or is supplied from the outside of the MFP  1 . The scanner unit  3  described above is arranged over the printer unit  2  and is coupled to the printer unit  2  with a coupling portion  2   a  that is provided on a rear side of the printer unit  2 . Hence, when a front portion of the scanner unit  3  is lifted, the scanner unit  3  is pivotally moved upward about the coupling portion  2   a  serving as a pivot with respect to the printer unit  2 , and thus the interior of the printer unit  2  is exposed. The scanner unit  3  includes an original document stage  7  and a lid  8 , and the lid  8  is arranged to cover the original document stage  7 . The scanner unit  3  reads an image recorded on an original document sheet in a state where the original document sheet is arranged between the original document stage  7  and the lid  8 . 
     The operation key  4  and the display  5  are arranged on an outer portion (here, a front portion) of the MFP  1 . The operation key  4  receives an operation input by a user. The display  5  displays particular information for the user. The display  5  is a touch panel type, and further functions as the operating interface with particular timing (S 12  to S 14 , S 17  and S 18  in a flowchart described later). 
     The control unit  6  controls the printer unit  2 , the scanner unit  3 , and the display  5  based on an input from the operation key  4  or an external input through a communication interface (not shown). 
     The printer unit  2  is controlled by the control unit  6 , and uses the ink supplied from a tank  12  so as to record the image on the recording sheet. The printer unit  2  includes a case  10  that forms part of the housing of the MFP  1  and that is formed in the shape of a rectangular parallelepiped. A cover  11  is attached to the case  10 . The cover  11  opens and closes an opening communicating with an internal space  13  provided within the case  10 . A plurality of tanks  12  is accommodated in the internal space  13 . A cap  15  is detachably attached to each tank  12 . 
     The cover  11  is provided in a front portion of the case  10  and, in the present embodiment, is coupled to the case  10  so as to pivotally move in a given range around an imaginary axis line P extending in a horizontal direction (for example, the width direction of the MFP  1 ). The cover  11  is opened and closed in a state where the scanner unit  3  is lifted from the printer unit  2 . When the cover  11  is opened ( FIG. 1B ), the internal space  13  is exposed. A tray  14  in which the recording sheets are stored is arranged within the case  10 . The tray  14  is pulled out forward with respect to the case  10  such that the recording sheets can be replenished. Note that the cover  11  is omitted in  FIGS. 1C and 1D  for simplicity. 
     The plurality of tanks  12  is accommodated in the internal space  13  in a state where the tanks  12  are aligned in the width direction. When the cover  11  is opened, the tanks  12  are exposed to the outside. A filling port  12   a  is formed in each tank  12 , and the ink that is filled through the filling port  12   a  is stored therein. The filling port  12   a  of the tank  12  in the present embodiment is provided in an upper portion of the tank  12 . The cap  15  is detachably attached to the filling port  12   a  so as to close the filling port  12   a.    
     Here, when the user replenishes the ink to the tank  12  through the filling port  12   a , a particular ink replenishment bottle  90  (see  FIG. 1D ) is used, and the ink flows out from the bottle opening of the bottle substantially at a constant outflow rate so as to be replenished to the tank  12 . Hence, by preliminarily grasping the outflow rate of the ink from the bottle opening of the bottle, the ink filling amount can be estimated by measuring a period during which the ink is filled, for example. 
     As an example, the MFP  1  performs color printing, and the tanks  12  correspond to the ink of respective colors (here, black, yellow, magenta and cyan). The MFP  1  may have a single tank so as to perform only the printing of a single color. 
     The MFP  1  further includes a cap placement area  9  at which the cap  15  removed from the filling port  12   a  of the tank  12  is placed (see  FIGS. 1A to 1D ). The cap placement area  9  in the present embodiment is provided in a region of the case  10  that faces the internal space  13  and, as an example, is provided at the rear side of the filling port  12   a . Here, the cap placement area  9  need not be necessarily provided at the rear side of the filling port  12   a . The position at which the cap placement area  9  is provided is not limited as long as the cap placement area  9  is provided at the case  10 . 
     [Functional Configuration of MFP] 
     In  FIG. 2 , the illustration of the configuration of the scanner unit  3  is omitted. As shown in  FIG. 2 , the MFP  1  includes various sensors, drivers, and so on forming the printer unit  2  in addition to the operation key  4 , the display  5 , and the control unit  6  described above. 
     Specifically, the printer unit  2  further includes a filling port open/close detection sensor  16 , motor driver ICs  30  and  31 , a head driver IC  32 , a conveyance motor  33 , a carriage motor  34 , a carriage  35 , a recording head  36 , and a cap placement area detection sensor  37 . The filling port open/close detection sensor  16  is a sensor for detecting open/close of the filling port  12   a  in the tank  12 . Specifically, the filling port open/close detection sensor  16  detects whether the cap  15  is attached to the filling port  12   a  of the tank  12  and also detects whether the ink replenishment bottle  90  is inserted in the filling port  12   a.    
     Various types of sensors may be used as the filling port open/close detection sensor  16 , such as an optical sensor and a magnetic sensor, and the filling port open/close detection sensor  16  is not limited to a particular type of sensor. As shown in  FIGS. 1B to 1D , in the present embodiment, an optical sensor is used as the filling port open/close detection sensor  16 . The filling port open/close detection sensor  16  has a light emitting portion and a light receiving portion. The control unit  6  determines (distinguishes) which of the cap  15  and the ink replenishment bottle  90  closes the filling port  12   a , based on a difference of output values of the filling port open/close detection sensor  16  at the time when light emitted from the light emitting portion and reflected by the cap  15  or the ink replenishment bottle  90  is received by the light receiving portion. More specifically, the control unit  6  determines (distinguishes) a state where the cap  15  is attached to the filling port  12   a  of the tank  12  ( FIG. 1B ), a state where none of the cap  15  and the ink replenishment bottle  90  is attached to the filling port  12   a  ( FIG. 1C ), and a state where the ink replenishment bottle  90  is inserted in the filling port  12   a  ( FIG. 1D ), based on the difference of the output values of the filling port open/close detection sensor  16 . That is the control unit  6  distinguishes these three states from one another. 
     Alternatively, a magnetic sensor may be used as the filling port open/close detection sensor  16 . In this case, too, the control unit  6  similarly determines (distinguishes) the above-mentioned states ( FIGS. 1B, 1C, and 1D ) based on the difference of the output values of the magnetic sensor. 
     The cap placement area detection sensor  37  is a sensor for detecting whether the cap  15  is placed at the cap placement area  9 . Similar to the filling port open/close detection sensor  16 , various types of sensors may be used as the cap placement area detection sensor  37 , such as an optical sensor and a magnetic sensor, and the cap placement area detection sensor  37  is not limited to a particular type of sensor. 
     The filling port open/close detection sensor  16  is provided for each of a plurality of colors, and detects an open/close state of the filling port  12   a  for each color. Similarly, the cap placement area detection sensor  37  is provided for each of the plurality of colors, and detects whether the cap  15  exists at the cap placement area  9  for each color. 
     As an example, the control unit  6  includes a CPU  20 , a memory (a ROM  21 , a RAM  22 , and an EEPROM  23 ) and an ASIC  24 . The CPU  20  is a controller of the MFP  1  to control the driver ICs  30  to  32  and the display  5 . The CPU  20  executes a particular program stored in the ROM  21  so as to also function as a cap open timer for measuring a period that elapses from when the cap  15  is detached from the filling port  12   a  until when the cap  15  is again attached to the filling port  12   a , and monitors an output value (detection signal) of the filling port open/close detection sensor  16 . The CPU  20  described above may be mounted on the control unit  6  as a single processor or mounted as a plurality of processors that cooperates with each other. 
     The ROM  21  stores a reading control program with which the CPU  20  controls the scanner unit  3  to perform a reading process on an image on an original document sheet and a printing control program with which the CPU  20  controls the printer unit  2  to perform a printing process. The EEPROM  23  stores various types of initial setting information inputted by the user. The motor driver ICs  30  and  31  and the head driver IC  32  are connected to the ASIC  24 . 
     When the CPU  20  receives a print job from the user, the CPU  20  outputs a print command to the ASIC  24  based on the printing control program. The ASIC  24  drives the driver ICs  30  to  32  based on the print command. 
     For example, the CPU  20  controls the motor driver IC  30  to drive the conveyance motor  33  and thereby convey the recording sheet. The CPU  20  controls the motor driver IC  31  to drive the carriage motor  34  and thereby move the carriage  35 . 
     The CPU  20  controls the head driver IC  32  to eject the ink from the recording head  36  mounted on the moving carriage  35  and thereby print the image data on the recording sheet that is conveyed. In this way, the printing process is performed. 
     The EEPROM  23  further stores a plurality of tables that are referenced as appropriate by the CPU  20 . As shown in  FIG. 3 , the EEPROM  23  stores an estimated filling amount table  17 , a variation amount correction coefficient table  18 , and a history table  19 . 
     The estimated filling amount table  17  is used for estimation of the ink remaining amount in the tank  12  by the CPU  20  after the user fills the ink into the tank  12 . An estimated filling amount Vw in the estimated filling amount table  17  is associated with a timer value Tc of the cap open timer (see  FIG. 4 ), and indicates an estimation value of the amount of ink filled into the tank  12  corresponding to the timer value Tc. An estimated variation amount Vd in the estimated filling amount table  17  is associated with the estimated filling amount Vw, and indicates a correctable range L (see  FIG. 8 ) in which an estimated ink remaining amount Vr estimated by the CPU  20  is corrected by the user so as to be increased or decreased. It is assumed that, as the timer value Tc is increased, a greater variation in the estimated filling amount Vw is produced. Thus, the estimated filling amount table  17  is set such that, as the estimated filling amount Vw is increased, the estimated variation amount Vd is increased. The CPU  20  uses the estimated filling amount table  17  that is the particular estimation standard described above so as to estimate the ink remaining amount in the tank  12 , thereafter updates the estimated filling amount table  17  based on the estimated ink remaining amount Vr corrected through the operating interface (the display  5 ) and stores the updated value in the EEPROM  23 . 
     The variation amount correction coefficient table  18  is used for adjusting the correctable range L based on ink remaining amount information Ir indicating the current amount of ink in the tank  12 . The ink remaining amount information Ir is stored in the RAM  22 , and is updated with particular timing. A correction upper limit coefficient and a correction lower limit coefficient in the variation amount correction coefficient table  18  are associated with the amount of ink indicated by the ink remaining amount information Ir, and are used as coefficients for adjusting the correction upper limit value and the correction lower limit value in the correctable range L according to the amount of ink. As the amount of ink indicated by the ink remaining amount information Ir is increased, the correction lower limit coefficient is set higher. As the amount of ink is decreased, the correction upper limit coefficient is set higher. 
     The history table  19  is used to update the estimated filling amount Vw in the estimated filling amount table  17  based on the ink filling amount Vi corrected by the user within the correctable range L. The timer value Tc in the history table  19  is associated with the ink filling amount Vi. The values in the tables shown in  FIG. 3  are merely examples, and may be changed as appropriate. 
     [Overall Operation of MFP] 
       FIG. 4  illustrates the operation of the MFP  1  for one of the plurality of tanks  12 , and the same is true for the operation of the MFP  1  for the other tanks  12 . 
     When the MFP  1  is in an energized state, the CPU  20  performs an ink management process of the tank  12  based on the printing control program. Specifically, the CPU  20  determines, based on a detection signal of the filling port open/close detection sensor  16 , whether the cap  15  is attached to the filling port  12   a  (step S 1 , hereinafter simply referred to as S 1 , and the same is true for the other steps). 
     When in S 1  the CPU  20  determines that the cap  15  is attached to the filling port  12   a , the CPU  20  returns the process to S 1 . When in S 1  the CPU  20  determines that the cap  15  is not attached to the filling port  12   a , the CPU  20  starts the cap open timer (S 2 ). Then, the CPU  20  determines whether the cap  15  is attached to the filling port  12   a  (S 3 ), and while the CPU  20  determines that the cap  15  is not attached to the filling port  12   a , the CPU  20  continues the measurement of the cap open timer. When in S 3  the CPU  20  determines that the cap  15  is attached to the filling port  12   a , the CPU  20  stops the cap open timer (S 4 ). 
     Then, the CPU  20  determines whether the timer value Tc is less than a particular period Ts that is preliminarily set (S 5 ). The particular period Ts may be set as appropriate with consideration given to, for example, the period that elapses from when the cap  15  is detached from the filling port  12   a  by the user until when the cap  15  is again attached to the filling port  12   a . The period indicated by the timer value Tc corresponds to a particular duration (hereinafter simply referred to as “duration”) that is included in the period that elapses from when the cap  15  is detached from the filling port  12   a  until when the cap  15  is again attached to the filling port  12   a.    
     When in S 5  the CPU  20  determines that the timer value Tc is less than the particular period Ts, the CPU  20  returns the process to S 1 . When in S 5  the CPU  20  determines that the timer value Tc is not less than the particular period Ts, the CPU  20  performs an ink remaining amount estimation confirmation process described later (S 6 ), resets the timer value Tc (S 7 ), and returns the flow. 
     In this way, when the timer value Tc is less than the particular period Ts (when it is assumed that the user simply checks the ink in the tank  12 ), the CPU  20  does not perform the confirmation process (S 6 ). And, only when the timer value Tc is longer than or equal to the particular period Ts (only when it is assumed that the user performs the operation of filling the ink into the tank  12 ), the CPU  20  performs the confirmation process (S 6 ). 
     Here, the duration described above is included in the period that elapses from when the cap  15  is detached from the filling port  12   a  until when the cap  15  is again attached to the filling port  12   a . Hence, the duration is determined based on at least any one of a first period that elapses from when the cap  15  is detached from the filling port  12   a  until when the cap  15  is again attached to the filling port  12   a , a second period that elapses from when the ink replenishment bottle  90  is inserted into the filling port  12   a  until when the ink replenishment bottle  90  is removed from the filling port  12   a , and a third period during which the cap  15  is placed at the cap placement area  9  and the ink replenishment bottle  90  is inserted in the filling port  12   a.    
     When the second period is measured, for example, whether the ink replenishment bottle  90  is inserted in the filling port  12   a  is detected based on the detection signal of the filling port open/close detection sensor  16 . When the third period is measured, whether the cap  15  is placed at the cap placement area  9  is detected based on the detection signal of the cap placement area detection sensor  37 . In other words, in this case, the CPU  20  uses the filling port open/close detection sensor  16  and the cap placement area detection sensor  37 , and thereby measuring the third period. The MFP  1  may be configured without having the cap placement area  9 . In this case, the duration is determined based on at least any one of the first period and the second period. 
     [Ink Filling Amount Estimation Confirmation Process] 
     As shown in  FIG. 5 , in the confirmation process (S 6 ), only when the cap  15  is removed from the filling port  12   a  and is again attached to the filling port  12   a , the CPU  20  receives an input of a replenishment completion report (declaration) through the operation key  4  indicating that the ink is replenished to the tank  12 , and updates, based on the replenishment completion report, the ink remaining amount information Ir stored in the RAM  22 . 
     Only when the duration (the timer value Tc) is longer than or equal to the particular period Ts, the CPU  20  estimates the ink remaining amount in the tank  12  based on the duration, displays the estimated ink remaining amount Vr on the display  5  and further receives, through the display  5  serving as the operating interface, whether the estimated ink remaining amount Vr displayed on the display  5  is correct (or appropriate). 
     Specifically, the CPU  20  reads the ink remaining amount information Ir from the RAM  22  (S 8 ), and thereafter reads the estimated filling amount table  17  from the EEPROM  23  (S 9 ). When the CPU  20  completes the reading of the estimated filling amount table  17  (S 10 ), the CPU  20  refers to the estimated filling amount table  17 , and determines (selects) the estimated filling amount Vw and the estimated variation amount Vd corresponding to the timer value Tc (S 11 ). Thereafter, the CPU  20  displays, on the display  5 , the estimated ink remaining amount Vr obtained by adding the estimated filling amount Vw selected in S 11  to the amount of ink indicated by the ink remaining amount information Ir (S 12 ). 
     In S 12 , the CPU  20  displays a particular confirmation screen  50  (see  FIG. 7 ) on the display  5 . The confirmation screen  50  includes a graphic  50   a  that shows the estimated ink remaining amount Vr, an NG (no good) button  50   b  and an OK button  50   c  for prompting the user to select whether the estimated ink remaining amount Vr in the graphic  50   a  is correct. 
     Then, the CPU  20  determines whether the NG button  50   b  is pressed by the user who looks at the confirmation screen  50  (S 13 ). In response to determining that the NG button  50   b  is not pressed, then the CPU  20  determines whether the OK button  50   c  is pressed (S 14 ). The CPU  20  repeats S 13  and S 14  until in S 14  the CPU  20  determines that the OK button  50   c  is pressed. Here, the CPU  20  in the present embodiment determines that in S 14  the OK button  50   c  is pressed, thereby receiving an input of the replenishment completion report. 
     When in S 14  the CPU  20  determines that the OK button  50   c  is pressed, then the CPU  20  updates the ink remaining amount information Ir based on the estimated ink remaining amount Vr in the graphic  50   a  and stores the updated ink remaining amount information Ir in the RAM  22  (S 20 ). 
     Then, the CPU  20  records, in the history table  19 , the timer value Tc of the cap open timer of which counting is stopped in S 4 . The CPU  20  also records, in the history table  19 , the ink filling amount Vi calculated based on the timer value Tc of the cap open timer, thereby recording the history (S 21 ). Here, because the input of replenishment completion report has been received without performing user&#39;s correction to the estimated ink remaining amount Vr calculated in S 12 , the CPU  20  records, as the ink filling amount Vi, the same value as the estimated filling amount Vw selected in S 11 , in the history table  19 . Then, the CPU  20  refers to the history table  19 , and newly calculates the estimated filling amount Vw based on the ink filling amount Vi corresponding to the latest timer value Tc and based on the ink filling amount Vi associated with the same timer value Tc as the latest timer value Tc and stored in the history table  19  (S 22 ). The CPU  20  updates the value of the estimated filling amount Vw in the estimated filling amount table  17  with the calculation result in S 22  (S 23 ). For example, if the latest timer value Tc=50 s, in S 22  the CPU  20  calculates an average value of all the ink filling amounts Vi stored in the history table  19  and associated with the timer value Tc=50 s, and in S 23  updates the estimated filling amount Vw with the average value. Note that the method of updating the estimated filling amount Vw is not limited to this. Then, the CPU  20  returns the step. 
     On the other hand, when in S 13  the CPU  20  determines that the NG button  50   b  is pressed, then the CPU  20  determines whether the amount of ink indicated by the ink remaining amount information Ir is smaller than a particular remaining amount Vs that is preliminarily set (S 15 ). The particular remaining amount Vs may be set as appropriate with consideration given to, for example, the number of sheets that can be printed with remaining ink in the MFP  1 . When in S 15  the CPU  20  determines that the amount of ink indicated by the ink remaining amount information Ir is smaller than the particular remaining amount Vs, the CPU  20  displays a particular correction screen  51  on the display  5  (see  FIG. 8 ), and receives the correction of the estimated ink remaining amount Vr by the user (S 17 ). When in S 15  the CPU  20  determines that the amount of ink indicated by the ink remaining amount information Ir is not smaller than the particular remaining amount Vs, the CPU  20  performs S 17  after performing an estimated variation amount correction process described later (S 16 ). 
     In other words, when the user makes a negative selection as to whether the estimated ink remaining amount Vr displayed on the display  5  is correct, in S 17  the CPU  20  displays, on the display  5 , the correction screen  51  in which the user corrects the estimated ink remaining amount Vr estimated by the CPU  20 , and receives an input of the estimated ink remaining amount Vr corrected through the operation key  4 . 
     As shown in  FIG. 8 , in S 17 , the CPU  20  displays the correction screen  51  on the display  5 . The correction screen  51  includes a graphic  51   a  that shows the estimated ink remaining amount Vr, amount setting keys  51   b  and  51   c  (an amount increasing key  51   b  and an amount decreasing key  51   c ) for adjustment of the estimated ink remaining amount Vr by the user, and an OK button  51   d . In the graphic  51   a , the correctable range L for the estimated ink remaining amount Vr is also displayed. When the amount increasing key  51   b  or the amount decreasing key  51   c  is pressed, the estimated ink remaining amount Vr in the graphic  51   a  is increased or decreased according to the amount of pressing within the correctable range L. The correctable range L corresponds to the upper limit value and the lower limit value of the estimated variation amount Vd at the present time (see  FIG. 3 ). 
     In the present embodiment, when the ink remaining amount information Ir read in S 8  is smaller than the particular remaining amount Vs, the CPU  20  performs S 17  without performing the estimated variation amount correction process (S 16 ) described later. In this case, the lower correctable range and the upper correctable range are not extended by the variation amount correction coefficient table  18 . 
     When the ink remaining amount indicated by the ink remaining amount information Ir is smaller than the particular remaining amount Vs, it is likely that the ink remaining amount in the tank  12  after the cap  15  is detached from the filling port  12   a  and again attached to the filling port  12   a  is smaller than a case where the ink remaining amount indicated by the ink remaining amount information Ir is larger than or equal to the particular remaining amount Vs. In S 17 , if the estimated ink remaining amount Vr of the graphic  51   a  is corrected to be a larger amount than the actual remaining amount, there is a possibility that ink in the tank  12  becomes empty while the MFP  1  is operating. In other words, because the ink remaining amount in the tank  12  recognized by the MFP  1  is larger than the actual remaining amount, the MFP  1  erroneously recognizes that ink still remains and performs printing although ink in the tank  12  is empty. As a result, actuators of the recording head  36  are driven without ejecting ink, and there is a possibility that an image different from print data desired by the user is printed. If the ink remaining amount in the tank  12  is large, there is a long period before the tank  12  becomes empty, and thus there is a possibility that ink is replenished before the tank  12  becomes empty. However, if the ink remaining amount in the tank  12  is small, there is only a short period before the tank  12  becomes empty, and thus there is a high possibility that the actuators of the recording head  36  are driven without ejecting ink. 
     Thus, when the ink remaining amount information Ir read in S 8  is smaller than the particular remaining amount Vs, the CPU  20  sets the upper limit value and the lower limit value of the correctable range L of the graphic  51   a  to the upper limit value and the lower limit value of the estimated variation amount Vd in the estimated filling amount table  17  read in S 11 , and receives correction by the user (S 17 ). This ensures that, when the ink remaining amount information Ir is smaller than the particular remaining amount Vs, the upper limit value of the correctable range L of the graphic  51   a  is not corrected to be larger than the upper limit value of the estimated variation amount Vd. As a result, in S 17 , the estimated ink remaining amount Vr is not corrected to exceed the upper limit value of the estimated variation amount Vd shown in the estimated filling amount table  17 , which suppresses a possibility that the actuators of the recording head  36  are driven without ejecting ink for a long period. 
     Then, the CPU  20  determines whether the OK button  51   d  in the correction screen  51  is pressed (S 18 ). In response to determining that the OK button  51   d  is pressed, the CPU  20  determines that a correction completion report of the estimated ink remaining amount by the user has been received. Reception of the correction completion report of the estimated ink remaining amount by the user may also serve as reception of the replenishment completion report. Then, the CPU  20  recalculates the estimated ink remaining amount Vr of the graphic  51   a  corrected in the correction screen  51  (S 19 ). Then, in S 20 , the CPU  20  updates the ink remaining amount information Ir based on the estimated ink remaining amount Vr recalculated in S 19 . After that, the CPU  20  records, in the history table  19 , the timer value Tc of the cap open timer of which counting is stopped in S 4 , and also records the ink filling amount Vi, thereby recording the history (S 21 ). More specifically, the CPU  20  calculates the ink filling amount Vi based on the estimated ink remaining amount Vr recalculated in S 19 , and records the calculated ink filling amount Vi together with the timer value Tc of the cap open timer in the history table  19 . After that, the CPU  20  sequentially performs S 22  and S 23  as described above. Due to these steps, the estimated filling amount Vw in the estimated filling amount table  17  is updated to a more accurate value by receiving the correction by the user. 
     [Estimated Variation Amount Correction Process] 
     As shown in  FIG. 6 , in the estimated variation amount correction process (S 16 ), the CPU  20  makes a setting such that the lower correctable range L of the estimated ink remaining amount Vr of the graphic  51   a  is extended more widely when the ink remaining amount indicated by the estimated ink remaining amount Vr calculated based on the timer value Tc is large, than when the ink remaining amount is small. 
     An acceptable range of correction of the lower correctable range L in the graphic  51   a  is larger when the estimated ink remaining amount Vr is large, than when the estimated ink remaining amount Vr is small. Thus, in S 15 , in response to determining that the ink remaining amount indicated by the ink remaining amount information Ir is larger than or equal to the particular remaining amount Vs, the CPU  20  refers to the variation amount correction coefficient table  18  and makes a setting such that the lower correctable range L of the estimated ink remaining amount Vr of the graphic  51   a  is extended more widely when the ink remaining amount indicated by the estimated ink remaining amount Vr is large, than when the ink remaining amount is small. This increases a degree of freedom of correction of the estimated ink remaining amount Vr by the user, and enables more accurate correction of the estimated ink remaining amount Vr. 
     In the estimated variation amount correction process (S 16 ), the CPU  20  makes a setting such that the upper correctable range L of the estimated ink remaining amount Vr of the graphic  51   a  is extended more widely when the ink remaining amount indicated by the estimated ink remaining amount Vr calculated based on the timer value Tc is small, than when the ink remaining amount is large. 
     That is, when the CPU  20  performs S 16 , the ink remaining amount indicated by the ink remaining amount information Ir is larger than or equal to the particular remaining amount Vs. Thus, even if in S 17  the estimated ink remaining amount Vr of the graphic  51   a  is corrected to be a larger amount than the actual amount, there is a long period before the tank  12  becomes empty and before the actuators of the recording head  36  are driven without ejecting ink. Hence, there is a higher possibility that ink is replenished before the tank  12  becomes empty than a case where the ink remaining amount indicated by the ink remaining amount information Ir is smaller than the particular remaining amount Vs. 
     An acceptable range of correction of the upper correctable range L in the graphic  51   a  is larger when the estimated ink remaining amount Vr is small, than when the estimated ink remaining amount Vr is large. Thus, in S 15 , in response to determining that the ink remaining amount indicated by the ink remaining amount information Ir is larger than or equal to the particular remaining amount Vs, the CPU  20  refers to the variation amount correction coefficient table  18  and makes a setting such that the upper correctable range L of the estimated ink remaining amount Vr of the graphic  51   a  is extended more widely when the ink remaining amount indicated by the estimated ink remaining amount Vr is small, than when the ink remaining amount is large. This increases a degree of freedom of correction of the estimated ink remaining amount Vr by the user, and enables more accurate correction of the estimated ink remaining amount Vr. 
     Specifically, the CPU  20  reads the ink remaining amount information Ir stored in the EEPROM  23  (S 24 ), and refers to the variation amount correction coefficient table  18  (S 25 ). Then, referring to the variation amount correction coefficient table  18 , the CPU  20  multiplies an estimated variation amount upper limit value by the correction upper limit coefficient corresponding to the ink amount indicated by the ink remaining amount information Ir, and sets this value as the new estimated variation amount upper limit value (S 26 ). Further, the CPU  20  multiplies an estimated variation amount lower limit value by the correction lower limit coefficient corresponding to the ink amount indicated by the ink remaining amount information Ir, and sets this value as the new estimated variation amount lower limit value (S 27 ). 
     Then, the CPU  20  determines whether the calculation in S 26  and S 27  is completed (S 28 ). When in S 28  the CPU  20  determines that the calculation is completed, the CPU  20  stores in the RAM  22  the estimated variation amount upper limit value set in S 26  and the estimated variation amount lower limit value set in S 27  (S 29 ). Thereafter, the CPU  20  performs S 17 . 
     In this way, the estimated variation amount upper and lower limit values newly stored in the RAM  22  are reflected in the correctable range L of the correction screen  51  displayed on the display  5  in S 17 . 
     Thus, when the ink remaining amount indicated by the ink remaining amount information Ir read in S 8  is larger than or equal to the particular remaining amount Vs, the correctable range L for the user&#39;s correction of the estimated ink remaining amount Vr can be appropriately changed depending on the value of the estimated ink remaining amount Vr calculated based on the timer value Tc. Thus, the estimated ink remaining amount Vr can be corrected accurately. 
     According to the MFP  1  described above, only when the CPU  20  determines, based on the detection signal of the filling port open/close detection sensor  16 , that the cap  15  is removed from the filling port  12   a  and is again attached to the filling port  12   a , the CPU  20  receives the input of the replenishment completion report to the operation key  4  indicating that ink is replenished to the tank  12  and, based on the replenishment completion report, updates the ink remaining amount information Ir stored in the RAM  22 . Thus, only when there is a high possibility that the cap  15  is removed and that the operation of replenishing the ink to the tank  12  is performed, the CPU  20  updates the ink remaining amount information Ir of the tank  12 . This suppresses an occurrence of an error between the ink remaining amount information Ir of the tank  12  managed by the CPU  20  and the actual ink remaining amount in the tank  12 . 
     Only when the CPU  20  determines, based on the detection signal of the filling port open/close detection sensor  16 , that the particular duration (the period indicated by the timer value Tc) included in the period that elapses from when the cap  15  is detached from the filling port  12   a  until when the cap  15  is again attached to the filling port  12   a  is longer than or equal to the particular period Ts, the CPU  20  estimates, from the duration, the ink remaining amount in the tank  12 , displays the estimated ink remaining amount Vr on the display  5  and further receives, through the operation key  4 , whether the estimated ink remaining amount Vr displayed on the display  5  is correct. This suppresses the occurrence of an error between the estimated ink remaining amount Vr estimated by the CPU  20  and the actual ink remaining amount. 
     The duration is determined based on at least one of the first period that elapses from when the cap  15  is detached from the filling port  12   a  until when the cap  15  is again attached to the filling port  12   a  and the second period that elapses from when the ink replenishment bottle  90  is inserted into the filling port  12   a  until when the ink replenishment bottle  90  is removed from the filling port  12   a . Thus, the flexibility of the setting of the duration is enhanced. 
     The duration is determined based on at least one of the first period that elapses from when the cap  15  is detached from the filling port  12   a  until when the cap  15  is again attached to the filling port  12   a , the second period that elapses from when the ink replenishment bottle  90  is inserted into the filling port  12   a  until when the ink replenishment bottle  90  is removed from the filling port  12   a , and the third period during which the cap  15  is placed at the cap placement area  9  and the ink replenishment bottle  90  is inserted in the filling port  12   a . Thus, the flexibility of the setting of the duration is enhanced. 
     When the user makes a negative selection on the estimated ink remaining amount Vr displayed on the display  5 , the CPU  20  displays, on the display  5 , the correction screen  51  in which the user corrects the estimated ink remaining amount Vr estimated by the CPU  20 , and receives the input of the estimated ink remaining amount Vr corrected through the operation key  4 . This suppresses the occurrence of an error between the estimated ink remaining amount Vr estimated by the CPU  20  and the actual ink remaining amount, by receiving confirmation of the user. 
     The CPU  20  makes a setting such that the lower correctable range L of the estimated ink remaining amount Vr in the correction screen  50  is extended more widely in a case where there is a large ink remaining amount indicated by the estimated ink remaining amount Vr displayed on the display  5  when the cap  15  is detached from the filling port  12   a , than a case where the ink remaining amount is small. This ensures (enlarges) the correctable range L, which is for correction by the user, of the estimated ink remaining amount Vr estimated by the CPU  20 . 
     The CPU  20  estimates the ink remaining amount by using the estimated filling amount table  17  that is the particular estimation standard, updates the estimation standard based on the estimated ink remaining amount Vr corrected through the operation key  4 , and stores the updated estimation standard in the EEPROM  23 . Thus, the CPU  20  appropriately estimates the ink remaining amount in the tank  12 . 
     While the disclosure has been described in detail with reference to the above aspects thereof, it would be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the claims. 
     For example, in the estimated filling amount table  17  of the above-described embodiment, the estimated filling amount Vw and the estimated variation amount Vd are stored in association with each other for each timer value Tc. However, there is no limitation to this configuration. For example, instead of the estimated filling amount Vw, a conversion value obtained by converting the estimated filling amount Vw of ink ejected from the recording head  36  into a dot count value may be used. Also, instead of the estimated variation amount Vd, preset variation values (an upper limit variation value and a lower limit variation value) for the above conversion value may be used. 
     The image recording apparatus of this disclosure is not limited to the MFP and may be applied to various types of apparatuses that use ink stored in a tank so as to record an image.