Patent Publication Number: US-2023150279-A1

Title: Printing apparatus and estimation method

Description:
The present application is based on, and claims priority from JP Application Serial Number 2021-185439, filed Nov. 15, 2021, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a printing apparatus and an estimation method. 
     2. Related Art 
     In the related art, a technique of estimating the remaining amount of a roll sheet is known. 
     As a technique of estimating the remaining amount of a roll sheet, JP-A-7-172683 discloses a technique of computing the remaining amount of a rolled recording medium from a reflection sensor that generates a detection signal each time the rolled recording medium is rotated by a predetermined amount, and the number of driving pulses for a driving motor of a recording sheet feed roller in the detection signal generation cycle of the reflection sensor. 
     The computation in JP-A-7-172683 utilizes a fact that there is a proportional relationship between the rotation amount of the rolled recording medium and the conveyance amount of the roll sheet recording medium. However, in a printing apparatus that performs printing on a roll sheet as that disclosed in JP-A-7-172683, the rotation amount of the roll sheet and the conveyance amount of the printing medium fed from the roll sheet are not necessarily proportional to each other. For example, to maintain the conveyance amount of the printing medium at a certain conveyance amount, it is necessary to increase the rotation amount of the roll sheet as the diameter of the roll sheet decreases. As described above, the computation in JP-A 172683 utilizes a fact that there is a proportional relation between the rotation amount of the rolled recording medium and the conveyance amount of roll sheet recording medium, and as such the remaining amount of the rolled recording medium may not be accurately computed. 
     SUMMARY 
     A printing apparatus of an aspect to solve the above-mentioned problems includes a feed mechanism configured to feed a printing medium from a roll sheet by rotating the roll sheet, a conveyance mechanism configured to convey the printing medium fed by the feed mechanism, a printing unit configured to perform printing on the printing medium conveyed by the conveyance mechanism, a first measurement unit configured to measure a cumulative rotation amount, the cumulative rotation amount being a cumulative value of a rotation amount of the roll sheet, a second measurement unit configured to measure a cumulative conveyance amount, the cumulative conveyance amount being a cumulative value of a conveyance amount of the printing medium conveyed by the conveyance mechanism, and an estimation unit configured to estimate a remaining amount of the roll sheet by using the following Equation (1): R=PF/(π·REV) . . . Equation (1), where the cumulative rotation amount measured by the first measurement unit is REV, the cumulative conveyance amount measured by the second measurement unit is PF, a diameter of the roll sheet is R, and π is a ratio of a circumference of a circle to its diameter. The first measurement unit resets the measured cumulative rotation amount each time the estimation unit estimates the remaining amount of the roll sheet or each time the estimation unit estimates the remaining amount of the roll sheet multiple times, the second measurement unit resets the measured cumulative conveyance amount each time the estimation unit estimates the remaining amount of the roll sheet or each time the estimation unit estimates the remaining amount of the roll sheet multiple times, and the estimation unit calculates the diameter of the roll sheet with the Equation (1), performs a filter process on the diameter of the roll sheet calculated, and estimates the diameter of the roll sheet subjected to the filter process as the remaining amount of the roll sheet. 
     An estimation method of another aspect to solve the above-mentioned problems is a method of a printing apparatus, the printing apparatus including a feed mechanism configured to feed a printing medium from a roll sheet by rotating the roll sheet, a conveyance mechanism configured to convey the printing medium fed by the feed mechanism, and a printing unit configured to perform printing on the printing medium conveyed by the conveyance mechanism, the estimation method comprising measuring a cumulative rotation amount, the cumulative rotation amount being a cumulative value of a rotation amount of the roll sheet, measuring a cumulative conveyance amount, the cumulative conveyance amount being a cumulative value of a conveyance amount of the printing medium conveyed by the conveyance mechanism, and estimating a remaining amount of the roll sheet by using the following Equation (1): R=PF/(π·REV) . . . Equation (1), where the cumulative rotation amount that is measured is REV, the cumulative conveyance amount that is measured is PF, a diameter of the roll sheet is R, and π is a ratio of a circumference of a circle to its diameter, resetting the measured cumulative rotation amount each time the remaining amount of the roll sheet is estimated or each time the remaining amount of the roll sheet is estimated multiple times, and resetting the measured cumulative conveyance amount each time the remaining amount of the roll sheet is estimated or each time the remaining amount of the roll sheet is estimated multiple times. In the estimation, the diameter of the roll sheet is calculated with the Equation (1), a filter process is performed on the diameter of the roll sheet calculated, and the diameter of the roll sheet subjected to the filter process is estimated as the remaining amount of the roll sheet. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a diagram illustrating a configuration of a label printer. 
         FIG.  2    is a diagram illustrating a feed control lever as viewed from above. 
         FIG.  3    is a diagram illustrating a feed control plate as viewed from the right side. 
         FIG.  4    is a block diagram illustrating a configuration of a control system of the label printer. 
         FIG.  5    is a flowchart illustrating an operation of the label printer. 
         FIG.  6    is a chart illustrating a relationship between a diameter of a roll sheet and a cumulative conveyance amount. 
         FIG.  7    is a chart for describing driving of a feed mechanism and a conveyance mechanism. 
         FIG.  8    is a chart illustrating a relationship between a diameter of a roll sheet and a cumulative conveyance amount. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     An embodiment is described below with reference to the accompanying drawings. 
       FIGS.  1 ,  2 , and  3    illustrate the X axis, the Y axis, and the Z axis. The X axis, the Y axis, and the Z axis are orthogonal to each other. The Z axis indicates the vertical direction. The X axis and the Y axis are parallel to the horizontal direction. The X axis indicates the left-right direction. The Y axis indicates the front-rear direction. The positive direction of the X axis indicates the rightward direction. The positive direction of the Y axis indicates the forward direction. The positive direction of the Z axis indicates the upward direction. 
       FIG.  1    is a diagram illustrating a configuration of a label printer  1 . 
     The label printer  1  is an example of “printing apparatus”. 
     The label printer  1  is a serial ink-jet printer. The label printer  1  houses a roll sheet RS, conveys the housed roll sheet RS in a conveyance direction H, and performs printing on the roll sheet RS with a printing head  2 , which is a serial ink-jet head. 
     The roll sheet RS is a rolled label sheet on which labels are pasted at a constant interval on a base sheet. The label printer  1  performs printing on the label of the roll sheet RS with the printing head  2 . 
     The label printer  1  includes a roll sheet housing unit  3  that houses the roll sheet RS. In the following description, in the roll sheet RS, a rolled portion that is housed in the roll sheet housing unit  3  is referred to as “roll main body” with a reference symbol “RB”. In addition, in the roll sheet RS, the label sheet fed and conveyed from roll main body RB is referred to as “conveyance roll sheet” with a reference symbol “RH”. 
     The conveyance roll sheet RH is an example of “printing medium”. 
     The roll sheet housing unit  3  includes a supporting member  4 . The supporting member  4  supports the roll main body RB through a cylindrical core member provided at the center portion of the roll main body RB. The supporting member  4  is connected to the motor shaft of a feed drive motor  5  through a power transmission mechanism, and is rotated in accordance with the driving of the feed drive motor  5 . In this manner, the roll main body RB rotates in conjunction with the rotation of the supporting member  4 , and the conveyance roll sheet RH is fed from the roll main body RB. A conveyance path through which the conveyance roll sheet RH is conveyed is formed in the label printer  1 . The conveyance roll sheet RH fed from the roll main body RB is conveyed in the conveyance direction H along the conveyance path. 
     The label printer  1  includes a feed control lever  6 . The feed control lever  6  is provided downstream of the roll sheet housing unit  3  in the conveyance direction H. The feed control lever  6  moves in accordance with the change of the length of the conveyance roll sheet RH between the roll sheet housing unit  3  and a conveyance roller pair  7 . More specifically, the feed control lever  6  rotates around a rotation shaft KJ extending in the left-right direction in accordance with the change of the length of the conveyance roll sheet RH between the roll sheet housing unit  3  and the conveyance roller pair  7 . 
     In the following description, the clockwise direction and the counterclockwise direction are rotational directions based on the feed control lever  6  as viewed from the right side. 
     The label printer  1  includes the conveyance roller pair  7 . The conveyance roller pair  7  is provided downstream of the feed control lever  6  in the conveyance direction H. The conveyance roller pair  7  includes a conveyance rotation roller  71 , and a conveyance driven roller  72  that rotates to follow the rotation of the conveyance rotation roller  71 . The conveyance driven roller  72  is provided at a position facing the conveyance rotation roller  71  in the conveyance path of the conveyance roll sheet RH. The conveyance rotation roller  71  is connected to a conveyance drive motor  8  through the power transmission mechanism not illustrated in the drawings, and is rotated in accordance with the driving of the conveyance drive motor  8 . The conveyance roller pair  7  sandwiches the conveyance roll sheet RH with the conveyance rotation roller  71  and the conveyance driven roller  72 , and conveys, in the conveyance direction H, the conveyance roll sheet RH fed from the roll sheet housing unit  3  through the rotation of the conveyance rotation roller  71 . 
     The label printer  1  includes a printing unit  9 . The printing unit  9  is provided downstream of the conveyance roller pair  7  in the conveyance direction H. The printing unit  9  includes a carriage  10 , and the printing head  2  mounted in the carriage  10 . 
     The printing unit  9  is an example of “printing unit”. 
     The carriage  10  is supported by a carriage shaft  11  extending in an orthogonal direction orthogonal to the conveyance direction H, and causes the printing head  2  to perform a scan in the orthogonal direction along the carriage shaft  11 . 
     The printing head  2  includes nozzle rows of four colors of CYMK, for example. The printing head  2  receives ink supplied from an ink reservoir part such as an ink cartridge and an ink tank not illustrated in the drawings, and forms dots on the conveyance roll sheet RH by ejecting the ink from the nozzle provided in each nozzle row. Note that the printing head  2  is not limited to a head that can perform color printing with the four colors of CMYK, and may be a head that can perform full-color printing using multi color ink including a special color ink in addition to the four colors of CMYK, or a head that can perform monochrome printing or two-color printing, for example. 
     A platen  12  is provided at a position facing the printing head  2  in the conveyance path of the conveyance roll sheet RH. The platen  12  is extended over a region where dots can be formed by the printing head  2 , and flattens and supports the conveyance roll sheet RH in such a manner that the surface of the conveyance roll sheet RH located at the platen  12  is perpendicular to the discharging direction of the ink ejected from the printing head  2 . Note that the platen  12  may be a so-called suctioning platen, which suctions the conveyance roll sheet RH by applying a suction force on the conveyance roll sheet RH. 
     The label printer  1  includes a control apparatus  13  that controls each unit of the label printer  1 . Details of the control apparatus  13  are described later. 
     The feed control lever  6  is specifically described below. 
       FIG.  2    is a diagram illustrating the feed control lever  6  as viewed from above. 
     The feed control lever  6  includes a feed control plate  61  and a tension member  62 . 
     The tension member  62  rotates around the rotation shaft KJ by following the change of the length of the conveyance roll sheet RH between the roll sheet housing unit  3  and the conveyance roller pair  7 . The tension member  62  is biased by a biasing member  63  such as a spring, and applies a predetermined tensile force to the conveyance roll sheet RH between the roll sheet housing unit  3  and the conveyance roller pair  7 . After being fed upward from the roll main body RB in the conveyance path of the conveyance roll sheet RH, the conveyance roll sheet RH is passed over the tension member  62  and bent forward. 
       FIG.  3    is a diagram illustrating the feed control plate  61  as viewed from the right side. 
     The feed control plate  61  is a member with a circular sector shape. The feed control plate  61  of the embodiment is composed of a light-shielding material. A cutout  611  is formed in the outer peripheral edge of the feed control plate  61 . The cutout  611  is formed to extend in the circumferential direction from a rear edge RTA corresponding to the radius of the circular sector. The length of the cutout  611  in the circumferential direction is a length corresponding to an angle θ 1 . The angle θ 1  is an angle from the rear edge RTA with a rotation center O of the rotation shaft KJ as the vertex. 
     The feed control plate  61  is provided such that in the vertical direction, the center of the circular sector is located at the rotation center O of the rotation shaft KJ. The feed control plate  61  rotates around the rotation shaft KJ in synchronization with the rotation of the tension member  62 . 
     The label printer  1  includes a detector  14 . The detector  14  is an optical sensor, and includes an irradiation unit  141  that emits light and a light reception unit  142  that receives light. The irradiation unit  141  is composed of a light emitting diode (LED), a laser light-emitting element or the like, for example. The light reception unit  142  is composed of a phototransistor, a photo IC or the like. The feed control plate  61  is provided between the irradiation unit  141  and the light reception unit  142  in the left-right direction. The irradiation unit  141  emits light toward the feed control plate  61 . The irradiation unit  141  of the embodiment emits light rightward. The light reception unit  142  is provided at a position facing the irradiation unit  141  with the light reception surface facing the feed control plate  61 . 
     When the portion irradiated by the irradiation unit  141  with light is a portion other than the cutout  611 , the light emitted by the irradiation unit  141  is blocked by the feed control plate  61 . In this case, the light reception unit  142  does not receive the light emitted by the irradiation unit  141 , and the detector  14  outputs a detection value of a Low-level. 
     On the other hand, when the portion irradiated by the irradiation unit  141  with light is the cutout  611 , the cutout  611  transmits the light emitted by the irradiation unit  141 . Therefore, the irradiation unit  141  receives the light emitted by the light reception unit  142 , and the detector  14  outputs a detection value of a High-level. 
     When the feed control lever  6  is located at the home position, the irradiation unit  141  irradiates a position Il with light. The home position of the feed control lever  6  is the position of the feed control lever  6  when the feed control lever  6  is rotated counterclockwise the most in the possible rotation range of the feed control lever  6 , and the home position is defined by biasing of the biasing member  63 . The feed control lever  6  does not rotate counterclockwise from the home position. When the feed control lever  6  rotates clockwise from the home position by an angle θ 2  or greater, the irradiation unit  141  irradiates the cutout  611  with light. 
       FIG.  4    is a block diagram illustrating a configuration of a control system of the label printer  1 . 
     The label printer  1  includes an input apparatus  15 , a display apparatus  16 , and a communication apparatus  17 . The input apparatus  15 , the display apparatus  16 , and the communication apparatus  17  are connected to the control apparatus  13 . The input apparatus  15  is an apparatus for the user of the label printer  1  to input a printing condition and the like, and is an input apparatus such as a keyboard and a mouse, for example. The input apparatus  15  may be a desktop or laptop personal computer, a tablet terminal, a mobile terminal or the like, and may be provided separately from the label printer  1 . The input apparatus  15  outputs information input by the operator, to the control apparatus  13 . The display apparatus  16  includes a display screen of a liquid crystal display panel or the like, and displays various information under the control of the control apparatus  13 . The communication apparatus  17  includes communication hardware such as a communication circuit according to a predetermined communication standard, and communicates with an apparatus provided separately from the label printer  1  in accordance with the predetermined communication standard. 
     The control apparatus  13  includes a processor  100  such as central processing unit (CPU) and micro processing unit (MPU), a memory  110 , an interface  120 , and a driving circuit  130 . 
     The processor  100  controls each unit of the control apparatus  13  by reading and executing a control program  111  stored in the memory  110 . The processor  100  includes a device control unit  101 , a printing control unit  102 , a first measurement unit  103 , a second measurement unit  104 , and an estimation unit  105  as functional units. The processor  100  functions as the device control unit  101 , the printing control unit  102 , the first measurement unit  103 , the second measurement unit  104 , and the estimation unit  105  by executing the control program  111  stored in the memory  110 . 
     The device control unit  101  corresponds to an example of “notification unit”. 
     The memory  110  stores the control program  111  to be executed by the processor  100 , setting data related to setting of the label printer  1 , and other various data. The memory  110  includes a nonvolatile storage region. In addition, the memory  110  may include a volatile storage region, and constitute a work area of the processor  100 . 
     The interface  120  includes communication hardware such as a connector and an interface circuit. The interface  120  is connected to the input apparatus  15 , the display apparatus  16  and the communication apparatus  17 , and conducts data communication with the apparatuses. 
     The label printer  1  includes a feed mechanism  18 , a conveyance mechanism  19 , a carriage movement unit  20 , the printing head  2 , and the detector  14 . 
     The feed mechanism  18  includes the feed drive motor  5  and the supporting member  4 . The feed drive motor  5  is connected to the control apparatus  13  and controlled by the control apparatus  13 . The control apparatus  13  rotates the supporting member  4  by driving the feed drive motor  5 . 
     The conveyance mechanism  19  includes the conveyance drive motor  8  and the conveyance roller pair  7 . The conveyance drive motor  8  is connected to the control apparatus  13  and controlled by the control apparatus  13 . The control apparatus  13  rotates the conveyance rotation roller  71  by driving the conveyance drive motor  8 , and causes the conveyance roller pair  7  to convey the conveyance roll sheet RH. 
     The carriage movement unit  20  includes the carriage  10 , a motor that causes the carriage  10  to perform a scan, the power transmission mechanism that transmits the power of the motor to the carriage  10 , and the like. The control apparatus  13  moves the carriage  10  in the left-right direction by driving the motor provided in the carriage movement unit  20 . 
     The printing head  2  is connected to the control apparatus  13 . The control apparatus  13  drives the printing head  2  to eject ink toward the conveyance roll sheet RH. By controlling the carriage movement unit  20  and the printing head  2 , the control apparatus  13  moves the carriage  10  while ejecting ink from the printing head  2 , and conveys the conveyance roll sheet RH in the conveyance direction H. 
     The detector  14  is connected to the control apparatus  13 . The control apparatus  13  acquires a detection value of the detector  14 , and reflects it to the control of the feed mechanism  18 . 
     As described above, the processor  100  functions as the device control unit  101 , the printing control unit  102 , the first measurement unit  103 , the second measurement unit  104 , and the estimation unit  105 . 
     The device control unit  101  receives an operation of the operator through the input apparatus  15 , causes the display apparatus  16  to display various information, and communicates with an apparatus provided separately from the label printer  1  through the communication apparatus  17 . The device control unit  101  notifies the user of the label printer  1  of the remaining amount of the roll sheet RS estimated by the estimation unit  105  described later. The device control unit  101  may provide the notification of the remaining amount of the roll sheet RS estimated by the estimation unit  105  by displaying information representing the remaining amount of the roll sheet RS on the display apparatus  16 . In addition, the device control unit  101  may provide the notification of the remaining amount of the roll sheet RS estimated by the estimation unit  105  by transmitting the information representing the remaining amount of the roll sheet RS to the terminal apparatus used by the user of the label printer  1  through the communication apparatus  17 . The device control unit  101  provides the notification of the remaining amount of the roll sheet RS when a trigger for performing the notification occurs. Examples of the trigger include the fact that the remaining amount of the roll sheet RS is estimated by the estimation unit  105 , the fact that the printing is completed, the fact that a preliminarily set time for performing the notification is reached, and the fact that an instruction to provide the notification of the remaining amount of the roll sheet RS is input from the user to the input apparatus  15 . 
     The printing control unit  102  performs printing on the conveyance roll sheet RH by controlling the feed mechanism  18 , the conveyance mechanism  19 , the carriage movement unit  20 , and the printing head  2 . 
     The printing control unit  102  drives the conveyance drive motor  8  in accordance with conveyance drive data. The conveyance drive data is data related to the driving of the conveyance drive motor  8 , and, in the conveyance drive data, the driving time for driving the conveyance drive motor  8 , the stop time for stopping the conveyance drive motor  8  and the like are described. The conveyance drive data is stored in the memory  110 . The printing control unit  102  of the embodiment drives the conveyance drive motor  8  in a control mode of repeating the drive and stop in a predetermined cycle in accordance with the conveyance drive data. 
     The printing control unit  102  controls the driving of the feed mechanism  18  on the basis of the detection value of the detector  14 . When the detector  14  outputs a Low-level detection value, the printing control unit  102  stops the driving of the feed drive motor  5 , and stops the feeding of the conveyance roll sheet RH from the roll main body RB. When the detector  14  outputs a High-level detection value, the printing control unit  102  feeds the conveyance roll sheet RH from the roll main body RB by driving the feed drive motor  5 . 
     The printing control unit  102  outputs the information about the rotational frequency and drive time of the feed drive motor  5  to the first measurement unit  103 . In addition, the printing control unit  102  outputs the information about the rotational frequency and drive time of the conveyance drive motor  8  to the second measurement unit  104 . 
     The first measurement unit  103  measures a cumulative rotation amount, which is a cumulative value of the rotation amount of the roll sheet RS. The first measurement unit  103  measures the cumulative rotation amount on the basis of the rotation amount of the feed drive motor  5 . The first measurement unit  103  acquires information about the rotational frequency and drive time of the feed drive motor  5  from the printing control unit  102 . Then, the first measurement unit  103  measures the cumulative rotation amount by calculating the rotation amount of the roll sheet RS from the acquired information, and counting the calculated rotation amount of the roll sheet RS in a cumulative manner. The first measurement unit  103  outputs the measured cumulative rotation amount to the estimation unit  105 . When first reset information is output from the estimation unit  105 , the first measurement unit  103  resets the measured cumulative rotation amount. Specifically, the first measurement unit  103  resets the value of the measured cumulative rotation amount to zero. After the reset, the first measurement unit  103  measures the cumulative rotation amount again from the value of zero. The cumulative rotation amount may be reset each time cumulative rotation amount is measured, or each time the cumulative rotation amount is measured multiple times. 
     The second measurement unit  104  measures a cumulative conveyance amount, which is a cumulative value of the conveyance amount of the conveyance roll sheet RH. The second measurement unit  104  measures the cumulative conveyance amount on the basis of the rotation amount of the conveyance drive motor  8 . The second measurement unit  104  acquires information about the rotational frequency and drive time of the conveyance drive motor  8  from the printing control unit  102 . Then, the second measurement unit  104  measures the cumulative conveyance amount by calculating the conveyance amount of the conveyance roll sheet RH from the acquired information, and counting the calculated conveyance amount of the conveyance roll sheet RH in a cumulative manner. When second reset information is output from the estimation unit  105 , the second measurement unit  104  resets the measured cumulative conveyance amount. Specifically, the second measurement unit  104  resets the value of the measured cumulative conveyance amount to zero. After the reset, the second measurement unit  104  measures the cumulative conveyance amount again from the value of zero. The cumulative conveyance amount may be reset each time the cumulative conveyance amount is measured, or each time the cumulative conveyance amount is measured multiple times. 
     The estimation unit  105  estimates the remaining amount of the roll sheet RS. 
     In the estimation of the remaining amount of the roll sheet RS, the estimation unit  105  calculates the diameter of the roll sheet RS by using the following Equation (1). 
         R=PF /(π· REV )  Equation (1)
 
     In Equation (1), R is the diameter of the roll sheet RS. In Equation (1), PF is the cumulative conveyance amount measured by the second measurement unit  104 . In Equation (1), n is the ratio of the circumference of a circle to its diameter. In Equation (1), REV is the cumulative rotation amount measured by the first measurement unit  103 . 
     In the estimation of the remaining amount of the roll sheet RS, the estimation unit  105  performs a filter process on the diameter of the roll sheet RS calculated with Equation (1), and sets the diameter of the roll sheet RS after the filter process as the remaining amount of the roll sheet RS. The estimation unit  105  performs a filter process such as a moving average filter process and a Kalman filter process, for example, on the diameter of the roll sheet RS calculated with Equation (1). The moving average filter process is a filter process with a moving average filter. The Kalman filter process is a filter process with a Kalman filter. 
     When performing the moving average filter process, the estimation unit  105  acquires the value to be subjected to the moving average filter process from the memory  110 , and determines the moving average value by using the acquired value to be subjected to the process and the diameter of the roll sheet RS calculated this time with Equation (1). Note that when the estimation unit  105  performs the moving average filter process, N values to be subjected to the moving average filter process are recorded in the memory  110 . Here, N is an integer of 1 or more. The N values recorded in the memory  110  are values representing the remaining amount of the roll sheet RS previously estimated by the estimation unit  105 , and are values representing the diameter of the roll sheet RS after the filter process. The N values recorded in the memory  110  are updated each time the estimation unit  105  estimates the remaining amount of the roll sheet RS. Specifically, the N values recorded in the memory  110  are updated such that the value of the remaining amount of the roll sheet RS estimated by the estimation unit  105  this time is included and that the oldest previously estimated remaining amount of the roll sheet RS is not included. 
     When performing the Kalman filter process, the estimation unit  105  acquires a value representing the remaining amount of the roll sheet RS estimated last time from the memory  110 . Then, the estimation unit  105  performs the Kalman filter process by using the value acquired from the memory  110  and the diameter of the roll sheet RS calculated this time with Equation (1). Note that when the estimation unit  105  performs the Kalman filter process, a value representing the remaining amount of the roll sheet RS estimated last time by the estimation unit  105  is recorded in the memory  110 . This value is updated to a value representing the remaining amount of the roll sheet RS estimated this time by the estimation unit  105  each time the estimation unit  105  estimates the remaining amount of the roll sheet RS. 
     After estimating the remaining amount of the roll sheet RS, the estimation unit  105  outputs first reset information to the first measurement unit  103 . The first reset information is information for an instruction of a reset of the cumulative rotation amount measured by the first measurement unit  103 . 
     In addition, after estimating the remaining amount of the roll sheet RS, the estimation unit  105  outputs second reset information to the second measurement unit  104 . The second reset information is information for an instruction of a reset of the cumulative conveyance amount measured by the second measurement unit  104 . 
     Next, an operation of the label printer  1  is described. 
       FIG.  5    is a flowchart illustrating an operation of the label printer  1 . 
     The printing control unit  102  of the label printer  1  determines whether to start the printing (step S 1 ). 
     For example, at step S 1 , when printing data is received from an external apparatus, the printing control unit  102  determines that the printing will be started. In addition, for example, when the device control unit  101  receives a printing start operation from the user through the input apparatus  15 , the printing control unit  102  determines that the printing will be started at step S 1 . 
     When the printing control unit  102  determines that the printing will not be started (step S 1 : NO), the printing control unit  102  performs the determination of step S 1  again. 
     When the printing control unit  102  determines that the printing will be started (step S 1 : YES), the first measurement unit  103  starts the measurement of the cumulative rotation amount (step S 2 ). 
     Next, the second measurement unit  104  starts the measurement of the cumulative conveyance amount (step S 3 ). 
     Note that the processing order of steps S 2  and S 3  may be reversed. In addition, steps S 2  and S 3  may be simultaneously performed. 
     Next, the estimation unit  105  determines whether the timing for estimating the remaining amount of the roll sheet RS has reached (step S 4 ). 
     Examples of the timing for estimating the remaining amount of the roll sheet RS include a timing when the cumulative rotation amount measured by the first measurement unit  103  has a predetermined threshold value or greater. 
     In addition, examples of the timing for estimating the remaining amount of the roll sheet RS include a timing when the cumulative conveyance amount measured by the second measurement unit  104  has a predetermined threshold value or greater. 
     When the estimation unit  105  determines that the timing for estimating the remaining amount of the roll sheet RS has not reached (step S 4 : NO), the processor  100  performs the determination of step S 8 . 
     On the other hand, when the estimation unit  105  determines that the timing for estimating the remaining amount of the roll sheet RS has reached (step S 4 : YES), it estimates the remaining amount of the roll sheet RS (step S 5 ). 
     Next, the first measurement unit  103  resets the measured cumulative rotation amount (step S 6 ). 
     Next, the second measurement unit  104  resets the measured cumulative conveyance amount (step S 7 ). Note that the processing order of steps S 6  and S 7  may be reversed. In addition, steps S 6  and S 7  may be simultaneously performed. 
     Next, the printing control unit  102  determines whether to terminate the printing (step S 8 ). 
     For example, when there is unprocessed data in the data included in the printing data, the printing control unit  102  makes a negative determination at step S 8 . 
     When the printing control unit  102  determines that the printing will not be terminated (step S 8 : NO), the printing control unit  102  performs the processes subsequent to step S 4  again. 
     On the other hand, when the printing control unit  102  determines that the printing will be terminated (step S 8 : YES), the printing control unit  102  terminates this process. 
     Next, the estimation accuracy of the estimation unit  105  is described. 
       FIG.  6    is a chart illustrating a relationship between the cumulative conveyance amount and the diameter of the roll sheet RS.  FIG.  6    illustrates a simulation result. 
     In the chart of  FIG.  6   , the ordinate is set to the diameter of the roll sheet RS, and the abscissa is set to cumulative conveyance amount. 
     The graph GF 1  of  FIG.  6    illustrates a relationship between a true diameter of the roll sheet RS and a cumulative conveyance amount. 
     The graph GF 2  of  FIG.  6    illustrates a relationship between the cumulative conveyance amount and the diameter of the roll sheet RS determined by a known method. The known method is a method of calculating the diameter of the roll sheet RS with Equation (1) without resetting the cumulative rotation amount measured by the first measurement unit  103  and the cumulative conveyance amount measured by the second measurement unit  104 . As is clear from the comparison between the graph GF 1  and the graph GF 2 , the diameter of the roll sheet RS determined by the known method has more errors with respect to the true diameter of the roll sheet RS as the cumulative conveyance amount increases. 
     The reason for this is as follows. 
     Equation (1) indicates that PF is in proportion to REV with πR as a coefficient. However, since the diameter of the roll sheet RS decreases as the cumulative conveyance amount increases, the rotation amount of the roll sheet RS with respect to the conveyance amount of the roll sheet RS per unit increases as the diameter of the roll sheet RS decreases. Specifically, in the known method, the diameter of the roll sheet RS is determined by substituting the cumulative conveyance amount and the cumulative rotation amount that are not actually proportional into Equation (1), which assumes a proportional relationship, without taking into account the variation of the diameter of the roll sheet RS. Consequently, in the known method, the error with respect to the true diameter of the roll sheet RS undesirably increases as the cumulative conveyance amount increases. 
     In  FIG.  6   , the plot of the black circle represents the diameter of the roll sheet RS calculated by the estimation unit  105  with Equation (1) in a configuration in which the cumulative conveyance amount and the cumulative rotation amount are reset each time the estimation unit  105  makes an estimation. The plot of  FIG.  6    changes along the graph GF 1  in accordance with the change of the cumulative conveyance amount even with errors with respect to the graph GF 1 . 
     The reason for this is as follows. 
     By resetting the cumulative rotation amount and the cumulative conveyance amount, the relationship between the cumulative rotation amount and the cumulative conveyance amount at the time of reset can be again set to the relationship corresponding to the diameter of the roll sheet RS at the time of reset. Thus, by resetting the cumulative conveyance amount and the cumulative rotation amount, the estimation unit  105  can take into account the change of the diameter of the roll sheet RS for the calculation of the diameter of the roll sheet RS. In this manner, the plot of  FIG.  6    changes along the graph GF 1 . 
     Note that the plot of  FIG.  6    has an error with respect to the graph GF 1  because the feed mechanism  18  and the conveyance mechanism  19  are asynchronously driven. 
       FIG.  7    is a chart for describing the driving of the feed mechanism  18  and the conveyance mechanism  19 . 
     In  FIG.  7   , the first ordinate is set to the cumulative conveyance amount. In  FIG.  7   , the second ordinate is set to the cumulative feeding amount. The cumulative feeding amount is a cumulative value of the feeding amount of the conveyance roll sheet RH from the roll sheet RS. The first ordinate and the second ordinate are the same scale. In  FIG.  7   , the abscissa is set to the time. 
     The graph GF 3  of  FIG.  7    illustrates a time variation of the cumulative conveyance amount. In addition, the graph GF 4  of  FIG.  7    illustrates a time variation of the cumulative feeding amount. 
     When the label printer  1  starts the printing at the timing T 1 , the conveyance mechanism  19  is driven, and the cumulative conveyance amount increases after the timing T 1 . Between the timings T 1  and T 2 , the driving of the feed mechanism  18  is stopped. Therefore, between the timings T 1  and T 2 , the conveyance roll sheet RH between the roll sheet housing unit  3  and the conveyance roller pair  7  is short. As a result, between the timings T 1  and T 2 , the feed control lever  6  rotates clockwise with the passage of time. 
     When the rotation angle of the feed control lever  6  from the home position becomes the angle θ 2  or greater at the timing T 2 , the detection value of the detector  14  changes from the Low-level to the High-level. When the detection value of the detector  14  changes to the High-level, the feed mechanism  18  is driven and the cumulative feeding amount increases after the timing T 2 . Note that when the feeding amount of the feed mechanism  18  per unit time is smaller than the conveyance amount of the conveyance mechanism  19  per unit time, the conveyance roll sheet RH between the roll sheet housing unit  3  and the conveyance roller pair  7  is short. In addition, when the feeding amount of the feed mechanism  18  per unit time is greater than the conveyance amount of the conveyance mechanism  19  per unit time, the conveyance roll sheet RH between the roll sheet housing unit  3  and the conveyance roller pair  7  is long. Therefore, the feed control lever  6  rotates clockwise when the feeding amount of the feed mechanism  18  per unit time is smaller than the conveyance amount of the conveyance mechanism  19  per unit time, whereas the feed control lever  6  rotates counterclockwise when the feeding amount of the feed mechanism  18  per unit time is greater than the conveyance amount of the conveyance mechanism  19  per unit time. 
     When the driving of the conveyance mechanism  19  is stopped at the timing T 3 , the increase of the cumulative conveyance amount is stopped after the timing T 3 . 
     When the rotation angle of the feed control lever  6  from the home position becomes smaller than the angle θ 2  between the timings T 3  and T 4 , the detection value of the detector  14  changes from the High-level to the Low-level. When the detection value of the detector  14  changes to the Low-level, the driving of the feed mechanism  18  is stopped, and the increase of the cumulative feeding amount stops after the timing T 4 . 
     When the driving of the conveyance mechanism  19  is started again at the timing T 5 , the cumulative conveyance amount increases again after the timing T 5 . 
     In this manner, in the label printer  1 , the conveyance mechanism  19  drives and stops in a predetermined cycle, and the feed mechanism  18  drives and stops in accordance with the change of the level of the detection value of the detector  14 . In this manner, in the label printer  1 , the conveyance mechanism  19  and the feed mechanism  18  asynchronously drive. 
     At the timing TA of  FIG.  7   , it is assumed that the timing for the estimation unit  105  to estimate the remaining amount of the roll sheet RS has reached. At the timing TA, the cumulative conveyance amount from a reference KJ 1  is smaller than the cumulative feeding amount from the reference KJ 1 . In this case, the diameter of the roll sheet RS calculated from Equation (1) at the timing TA is calculated as a value smaller than the true diameter of the roll sheet RS. 
     It is assumed that the timing for the estimation unit  105  to estimate the remaining amount of the roll sheet RS has reached at the timing TB of  FIG.  7   . At the timing TB, the cumulative conveyance amount from a reference KJ 2  is greater than the cumulative feeding amount from a reference KJ 3 . In this case, the diameter of the roll sheet RS calculated from Equation (1) at the timing TB is calculated as a value greater than the true diameter of the roll sheet RS. Note that the cumulative conveyance amount from the reference KJ 2  is a cumulative conveyance amount of a case where the cumulative conveyance amount at the timing TA is set as zero. In addition, the cumulative feeding amount from the reference KJ 3  is a cumulative feeding amount of a case where the cumulative feeding amount at the timing TA is set to zero. 
     It is assumed that the timing for the estimation unit  105  to estimate the remaining amount of the roll sheet RS has reached at the timing TC of  FIG.  7   . At the timing TC, the cumulative conveyance amount from a reference KJ 4  is greater than the cumulative feeding amount from the reference KJ 4 . In this case, the diameter of the roll sheet RS calculated from Equation (1) at the timing TC is calculated as a value greater than the true diameter of the roll sheet RS. Note that the cumulative conveyance amount and the cumulative feeding amount from the reference KJ 4  are a cumulative conveyance amount and a cumulative feeding amount of a case where the cumulative conveyance amount and the cumulative feeding amount at the timing TB are set to zero. 
     It is assumed that the timing for the estimation unit  105  to estimate the remaining amount of the roll sheet RS has reached at the timing TD of  FIG.  7   . At the timing TD, the cumulative conveyance amount from a reference KJ 6  is greater than the cumulative feeding amount from a reference KJ 5 . In this case, the diameter of the roll sheet RS calculated from Equation (1) at the timing TD is calculated as a value greater than the true diameter of the roll sheet RS. Note that the cumulative conveyance amount from the reference KJ 6  is a cumulative conveyance amount of a case where the cumulative conveyance amount at the timing TC is set as zero. In addition, the cumulative feeding amount from the reference KJ 5  is a cumulative feeding amount of a case where the cumulative feeding amount at the timing TC is set to zero. 
     As described above, since the feed mechanism  18  and the conveyance mechanism  19  asynchronously drive, the cumulative feeding amount may be greater than the cumulative conveyance amount or the cumulative feeding amount may be smaller than the cumulative conveyance amount depending on the timing of the estimation of the estimation unit  105 . The cumulative feeding amount is an amount defined by the diameter of the roll sheet RS and the cumulative rotation amount of the roll sheet RS. As such, when the cumulative feeding amount is large with respect to the cumulative conveyance amount, the relationship between the cumulative conveyance amount and the cumulative rotation amount to be substituted into Equation (1) may not have a constant relationship. As a result, the diameter of the roll sheet RS calculated from Equation (1) may have an error with respect to the true diameter of the roll sheet RS. As a result, the plot of  FIG.  6    has an error with respect to the true diameter of the roll sheet RS. In view of this, the estimation unit  105  performs the filter process in order to suppress the error with respect to the true diameter of the roll sheet RS. 
       FIG.  8    is a chart illustrating a relationship between the cumulative conveyance amount and the diameter of the roll sheet RS.  FIG.  8    illustrates a simulation result. 
     In  FIG.  8   , the ordinate is set to the diameter of the roll sheet RS, and the abscissa is set to the cumulative conveyance amount. 
     The graph GF 1  of  FIG.  8    is the same as the graph GF 1  of  FIG.  6   . The graph GF 2  of  FIG.  8    is the same as the graph GF 2  of  FIG.  6   . 
     The graph GF 5  of  FIG.  8    is a graph obtained by performing a moving average filter process on the plot of  FIG.  6   . As is clear from the comparison between the graph GF 5  of  FIG.  8    and the plot of  FIG.  6   , the graph GF 5  of  FIG.  8    has fewer errors with respect to the graph GF 1  than the plot of  FIG.  6   . 
     As described above with reference to  FIGS.  6  and  8   , through the reset of the first measurement unit  103  and the second measurement unit  104  and the filter process of the estimation unit  105 , the estimation unit  105  can accurately estimate the remaining amount of the roll sheet RS. 
     As described above, the label printer  1  includes the feed mechanism  18  that feeds the conveyance roll sheet RH from the roll sheet RS by rotating the roll sheet RS, the conveyance mechanism  19  that conveys the conveyance roll sheet RH fed by the feed mechanism  18 , the printing unit  9  that performs printing on the conveyance roll sheet RH conveyed by the conveyance mechanism  19 , the first measurement unit  103  that measures the cumulative rotation amount of the roll sheet RS, the second measurement unit  104  that measures the cumulative conveyance amount of the conveyance roll sheet RH conveyed by the conveyance mechanism  19 , and the estimation unit  105  that estimates the remaining amount of the roll sheet RS by using Equation (1) in which the cumulative rotation amount measured by the first measurement unit  103  is REV, the cumulative conveyance amount measured by the second measurement unit  104  is PF, and the diameter of the roll sheet RS is R. The first measurement unit  103  resets the measured cumulative rotation amount each time the estimation unit  105  estimates the remaining amount of the roll sheet RS or each time the estimation unit  105  estimates the remaining amount of the roll sheet RS multiple times. The second measurement unit  104  resets the measured cumulative conveyance amount each time the estimation unit  105  estimates the remaining amount of the roll sheet RS or each time the estimation unit  105  estimates the remaining amount of the roll sheet RS multiple times. The estimation unit  105  estimates the remaining amount of the roll sheet RS by calculating the diameter of the roll sheet RS with Equation (1) and performing the filter process on the calculated diameter of the roll sheet RS. 
     In this manner, the remaining amount of the roll sheet RS can be estimated in consideration of the diameter of the roll sheet RS by resetting the cumulative rotation amount measured by the first measurement unit  103  and the cumulative conveyance amount measured by the second measurement unit  104 . In addition, the error between the diameter of the roll sheet RS calculated with Equation (1) and the true diameter of the roll sheet RS can be reduced by performing the filter process on the diameter of the roll sheet RS calculated with Equation (1). Thus, the label printer  1  can accurately estimate the remaining amount of the roll sheet RS. 
     The filter process is a moving average filter process. 
     In this manner, through the filter process of the moving average filter, the error between the diameter of the roll sheet RS calculated with Equation (1) and the true diameter of the roll sheet RS can be suppressed. In addition, by using the moving average filter process, the diameter of the roll sheet RS can be accurately determined at the timing for the estimation of the estimation unit  105 . Thus, the label printer  1  can accurately estimate the remaining amount of the roll sheet RS at the timing for the estimation of the estimation unit  105 . 
     The filter process is a Kalman filter process. 
     In this manner, through the filter process of the Kalman filter, the error between the diameter of the roll sheet RS calculated with Equation (1) and the true diameter of the roll sheet RS can be suppressed. In addition, by using the filter process of the Kalman filter, the diameter of the roll sheet RS can be accurately determined at the timing for the estimation of the estimation unit  105 . In addition, by using the Kalman filter process, it suffices that at least the label printer  1  stores the remaining amount of the roll sheet RS estimated last time by the estimation unit  105 , and it is not necessary to use a large storage region of the memory  110 . Thus, the label printer  1  can accurately estimate the remaining amount of the roll sheet RS at the timing for the estimation of the estimation unit  105  while suppressing the increase of the use rate of the memory  110 . 
     The feed mechanism  18  and the conveyance mechanism  19  are asynchronously driven. 
     In this manner, even when the difference between the diameter of the roll sheet RS calculated with Equation (1) and the true diameter of the roll sheet RS is a difference due to the asynchronous driving of the feed mechanism  18  and the conveyance mechanism  19 , the difference can be suppressed. Thus, even with the label printer  1  in which the feed mechanism  18  and the conveyance mechanism  19  asynchronously drive, the remaining amount of the roll sheet RS can be estimated. 
     The label printer  1  includes the device control unit  101  that provides the notification of the remaining amount of the roll sheet RS estimated by the estimation unit  105 . 
     In this manner, the user of the label printer  1  can determine the remaining amount of the roll sheet RS. 
     The estimation method of the label printer  1  includes a step of measuring the cumulative rotation amount of the roll sheet RS, a step of measuring the cumulative conveyance amount of the conveyance roll sheet RH, a step of estimating the remaining amount of the roll sheet R by using Equation (1) in which the measured cumulative rotation amount is REV, the measured cumulative conveyance amount is PF, and the diameter of the roll sheet RS is R, a step of resetting the measured cumulative rotation amount each time the remaining amount of the roll sheet RS is estimated or each time the remaining amount of the roll sheet RS is estimated multiple times, and a step of resetting the measured cumulative conveyance amount each time the remaining amount of the roll sheet RS is estimated or each time the remaining amount of the roll sheet RS is estimated multiple times. In the estimation method, the diameter of the roll sheet RS is calculated with Equation (1) in the estimating step, and the remaining amount of the roll sheet RS is estimated by performing the filter process on the calculated diameter of the roll sheet RS. 
     In this manner, effects similar to those of the label printer  1  described above can be achieved. 
     The above-described embodiment is only one specific example of the application of the present disclosure. The disclosure is not limited to the configurations of the above-described embodiment, but can be implemented in various forms to the extent that it does not depart from the gist of the disclosure. 
     For example, in the above-described embodiment, the label printer  1  is exemplified as a printing apparatus. However, the printing apparatus is not limited to the label printer  1 . It suffices that the printing apparatus is an apparatus including the feed mechanism  18  that houses the roll sheet RS and feeds the roll sheet RS, and the conveyance mechanism  19  that conveys the conveyance roll sheet RH fed from the roll sheet RS. Specifically, the printing apparatus may be a large-format printer, a textile printer that performs textile printing, or the like. 
     While a serial-head type is exemplified as the printing head  2  in the above-described embodiment, a line-head type may also be adopted. In addition, the printing system of the printing head  2  is not limited to an ink-jet type. 
     In the above-described embodiment, the feed mechanism  18  includes the feed drive motor  5  and the supporting member  4 . However, the feed mechanism  18  may include one or a plurality of rollers provided upstream of the feed control lever  6 . The roller included in the feed mechanism  18  may be a rotation roller, a driven roller, or both. In addition, the feed mechanism  18  may include various types of power transmission mechanisms related to feeding of the conveyance roll sheet RH. 
     In the above-described embodiment, the conveyance mechanism  19  includes the conveyance drive motor  8  and the conveyance roller pair  7 . However, the conveyance mechanism  19  may include one or a plurality of rollers provided downstream of the feed control lever  6 . The roller included in the conveyance mechanism  19  may be a rotation roller, a driven roller, or both. In addition, the conveyance mechanism  19  may include various types of power transmission mechanisms related to the conveyance of the conveyance roll sheet RH. 
     Instead of the cutout  611 , a hole, or a member that transmits light emitted by the irradiation unit  141 , may be formed in the feed control plate  61 . 
     In the above-described embodiment, the moving average filter process and the Kalman filter process are exemplified as the filter process performed by the estimation unit  105 . However, the filter process performed by the estimation unit  105  is not limited to the two types of filter processes. For example, the estimation unit  105  may be configured to perform a filter process of a primary delay filter, or a filter process of a secondary delay filter. 
     The processor  100  may be composed of a single processor, or a plurality of processors. The processor  100  may be hardware programed to achieve the corresponding functional part. Specifically, the processor  100  may be composed of an application specific integrated circuit (ASIC), or a field programmable gate array (FPGA), for example. 
     In addition, the units of the label printer  1  illustrated in  FIG.  4    are examples, and their specific mounting configurations are not limited. Specifically, it is not necessarily required to mount hardware individually corresponding to each unit, and it is naturally possible to adopt a configuration in which the function of each unit is achieved when one processor executes a program. In addition, a part of the function achieved by software in the above-described embodiment may be achieved by hardware, or a part of the function achieved by hardware may be achieved by software. Further, specific unit configurations of other units of the label printer  1  may also be arbitrarily changed. 
     In addition, for example, the units of steps of the operation illustrated in  FIG.  5    are units divided in accordance with the main processing content for convenience of description of the operation of each unit of the label printer  1 , and the present disclosure is not limited to the way of dividing the processing units and the names of the units. The units may be divided into a larger number of step units in accordance with the processing content. In addition, the units may be divided such that one step unit includes a larger number of processes. In addition, the order of the steps may be interchanged as appropriate to the extent that it does not interfere with the purpose of the disclosure.