Printing device

Abstract

To provide a printing device that can reduce the risk that stability of operation deteriorates, when executing printing processing to a medium including calcium carbonate.SOLUTION: A printing device comprises: printing means that performs printing on a medium including calcium carbonate; conveying means that rotates and drives a conveying belt constituting at least a portion of a conveyance passage on which the medium is conveyed; voltage supply means that supplies electrifying voltages to an electrifying roller that electrifies the conveying belt; detecting means that detects whether abnormal electrification is occurring in the conveying belt or not; determining means that determines whether the cause of the abnormal electrification is an abnormality in the voltage supply means or an abnormality in the conveying belt; and machine learning means that performs machine learning of a determination condition in the determining means based on a learning model having a rotation speed of the conveying belt and a result of detection performed by the detecting means associated with each other.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a printing device. [Background technology]

[0002] In recent years, there has been tremendous innovation in printing technology, and printing is now performed on a wide variety of media. For example, Patent Document 1 discloses a printing medium having a plaster printing layer as a medium on which printing is performed.

[0003] Furthermore, in a printing device, a medium is transported to a desired transport position by a transport belt, and a printing process is executed on the medium by a printing means such as an inkjet method or an electrophotographic method, thereby forming a desired image on the medium. For example, Patent Document 2 discloses a technology in which a transport belt made of polyethylene terephthalate is charged to attract the medium, and the transport belt is driven to transport the medium to the desired transport position and execute a printing process on the transported medium. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2008 / 013294 [Patent Document 2] JP 2007-210725 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when printing is performed over a long period of time on a medium containing calcium carbonate, such as lime plaster as described in Patent Document 1, the calcium carbonate contained in the medium accumulates inside the printing device, and the accumulated calcium carbonate reacts with moisture in the air and solidifies. Such solidified calcium carbonate is harder than the polyethylene terephthalate that constitutes the conveyor belt described in Patent Document 2, and therefore there is a risk of damaging the conveyor belt.

[0006] In particular, in a printing device such as that described in Patent Document 2, a high-voltage circuit supplies a high voltage to the conveyor belt to charge the conveyor belt, thereby adsorbing the media to the conveyor belt and achieving stable media transport. Therefore, if the conveyor belt is scratched by solidified calcium carbonate, an abnormality occurs in the charging voltage applied to the conveyor belt, and the printing process may be stopped.

[0007] In other words, when a printing device such as that described in Patent Document 2 is used to perform a printing process on a medium containing calcium carbonate such as that described in Patent Document 1, there was a risk that the operational stability of the printing device would decrease. [Means for solving the problem]

[0008] One aspect of the printing device according to the present invention is to A printing means for printing on a medium containing calcium carbonate; a conveying unit that rotates a conveying belt that constitutes at least a part of a conveying path along which the medium is conveyed; a voltage supplying means for supplying a charging voltage to a charging roller for charging the conveyor belt; a detection means for detecting whether or not a charging abnormality occurs on the conveyor belt; a discrimination means for discriminating whether the cause of the charging abnormality is an abnormality in the voltage supply means or an abnormality in the conveyor belt; a machine learning means for learning by machine learning a discrimination condition in the discrimination means based on a learning model in which the rotation amount of the conveyor belt and the detection result of the detection means are associated with each other; Equipped with. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a diagram showing the external structure of a printing apparatus. [Diagram 2] FIG. 2 is a diagram illustrating the internal structure of a printing device. [Diagram 3] 11 is a diagram illustrating an example of a medium ejection path. [Figure 4] FIG. 4 is a diagram showing an example of a structure around a print transport path; [Diagram 5] FIG. 2 illustrates an example of a functional configuration of a printing apparatus. [Figure 6] FIG. 2 is a diagram illustrating a functional configuration of a detection unit. [Figure 7] FIG. 2 is a diagram illustrating an example of the configuration of a machine learning unit. [Figure 8] FIG. 13 is a diagram showing a case where no charging abnormality occurs in an area between arbitrary positions p1 and p2 on a conveyor belt. [Figure 9] FIG. 13 is a diagram showing a case where a charging abnormality occurs due to an abnormality in a voltage supply unit in an area between arbitrary positions p1 and p2 on the conveyor belt. [Figure 10] FIG. 13 is a diagram showing a case where a charging abnormality occurs due to an abnormality in the conveyor belt in a region between arbitrary positions p1 and p2 on the conveyor belt. [Figure 11] FIG. 11 is a flow chart illustrating an example of the operation of the discrimination unit. [Figure 12] FIG. 2 is a diagram showing an example of a coating material that can be used on the transport belt. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Preferred embodiments of the present invention will be described below with reference to the drawings. The drawings are used for the convenience of explanation. Note that the embodiments described below do not unduly limit the contents of the present invention described in the claims. Furthermore, not all of the configurations described below are necessarily essential components of the present invention.

[0011] In the following description, an inkjet printer that prints an image by ejecting ink onto a medium will be taken as an example of a printing device according to the present invention. However, the printing device is not limited to an inkjet printer, and may be, for example, a dot impact printer, a thermal transfer printer, a laser printer, or a copying machine such as a copy machine. Furthermore, the printing device may be a so-called multifunction machine that combines a scanner, a fax, and the like in addition to an inkjet printer, a dot impact printer, a thermal transfer printer, and a laser printer.

[0012] 1. Printing device structure First, an example of the structure of a printing device in this embodiment will be described. Fig. 1 is a diagram showing the external structure of a printing device 1. The printing device 1 in this embodiment is a printing device capable of printing on a medium containing calcium carbonate, specifically, plaster paper coated with plaster, and is, for example, a so-called inkjet printer that prints by ejecting or applying ink, which is a water-soluble printing material, onto a medium.

[0013] In the following description, the direction corresponding to the depth direction of the printing device 1 may be referred to as the X direction, the direction corresponding to the width direction of the printing device 1 as the Y direction, and the direction corresponding to the height direction of the printing device 1 along the direction of gravity as the Z direction. In the following description, the direction in which the medium is transported may be referred to as the "downstream" and the opposite side as the "upstream". In the following description, the X direction, Y direction, and Z direction are described as being mutually orthogonal, but this is not limited to the configurations of the printing device 1 being disposed orthogonal to each other.

[0014] 1, the printing device 1 includes a device main body 2A that prints on a medium, a scanner unit 3 located above the device main body 2A, and additional units 2B and 2C located below the device main body 2A. The device main body 2A also includes a medium cassette 10A, an output tray 4, an operation panel 5, and a feeding unit 35.

[0015] Operation information for the user to perform various operations of the printing device 1 is input to the operation panel 5. Such an operation panel 5 may be, for example, a so-called touch panel in which an operation section to which operation information by the user is input and a display section to notify the user of information are stacked together. That is, the operation panel 5 is an operation means for accepting operations of the printing device 1 by the user, and also functions as a notification means for notifying the user of the status of the printing device 1. Note that the operation panel 5 of the printing device 1 may be configured to separately include a push switch that the user presses and a display panel to notify the user of information.

[0016] The discharge tray 4 is an outlet through which media is discharged after printing processing has been performed in the printing device 1, and the discharge tray 4 provided in the printing device 1 of this embodiment corresponds to a face-down discharge tray in which media is discharged with the printed side that has most recently been printed facing down.

[0017] The medium cassette 10A contains media on which a printing process is executed in the printing device 1. The printing device 1 sequentially feeds out the media contained in the medium cassette 10A from the medium cassette 10A, executes a printing process on the fed-out media, and ejects the media from the ejection tray 4.

[0018] A feeding unit 35 is located on the side of the printing device 1. The feeding unit 35 includes an opening / closing cover 6 that can be opened and closed relative to the device body 2A by rotating around a swing shaft 6a described later. That is, the opening / closing cover 6 is configured to be swingable around the swing shaft 6a, and opens and closes in the directions indicated by the arrows e and f shown in FIG. 1. In the printing device 1 of this embodiment, it is also possible to perform printing processing on a medium supplied from the feeding unit 35, and the medium on which printing processing has been performed is discharged from the discharge tray 4. That is, the feeding unit 35 corresponds to a so-called manual feed tray used when a user manually inserts a medium. Here, the imaginary line and the reference symbol 6-1 shown in FIG. 1 indicate a state in the middle of opening and closing the opening / closing cover 6.

[0019] The expansion unit 2B includes a medium cassette 10B, and the expansion unit 2C includes a medium cassette 10C. The expansion units 2B and 2C are optional units for increasing the number of sheets of media stored in the printing device 1, and can be optionally attached to and detached from the device main body 2A.

[0020] In the printing device 1 configured as described above, the medium supplied from the medium cassettes 10A, 10B, 10C or the feeding unit 35 is transported in a direction along the left-right direction of the printing device 1 based on operation information input via the operation panel 5, and a printing process is performed on the transported medium. The medium on which the printing process has been performed is then discharged from the discharge tray 4. Note that the printing device 1 may perform the printing process based on image information supplied from an external terminal such as a personal computer provided outside the printing device 1, in addition to the operation information input via the operation panel 5.

[0021] Next, an example of a transport path along which the medium is transported inside the printing device 1 will be described. FIG. 2 is a diagram showing the internal structure of the printing device 1. FIG. 2 shows three medium feed trajectories, namely, a feed trajectory S1 when the medium is fed from the medium cassette 10A, a feed trajectory S2 when the medium is fed from the medium cassettes 10B and 10C (not shown in FIG. 2), and a feed trajectory S3 when the medium is fed from the feeding unit 35, and two medium discharge trajectories, namely, a discharge trajectory T1 when the medium is discharged with the printed side on which the most recent printing process has been performed facing up, and a discharge trajectory T2 when the medium is discharged with the printed side on which the most recent printing process has been performed facing down. In the following description, discharging the medium with the printed side on which the most recent printing process has been performed facing up may be referred to as face-up discharge, and discharging the medium with the printed side on which the most recent printing process has been performed facing down may be referred to as face-down discharge.

[0022] FIG. 2 also illustrates five media transport paths along which the media is transported: a print transport path R1, a switchback transport path R2, a reversing transport path R3, a face-down transport path R4, and a face-up transport path R5.

[0023] As shown in FIG. 2, a flap 33 is provided on the medium transport path along which the medium is transported. The flap 33 is driven by a drive source (not shown). This allows the transport path along which the medium is transported to be switched between the face-down transport path R4 and the face-up transport path R5. Specifically, the flap 33 is switched between a state shown by a solid line in FIG. 2 and a state shown by a virtual line and reference symbol 33-1. When the flap 33 is in the state shown by the solid line, the medium is guided to the face-down transport path R4 and discharged to the discharge tray 4 along the discharge trajectory T2. On the other hand, when the flap 33 is in the state shown by the virtual line and reference symbol 33-1 in FIG. 2, the medium is guided to the face-up transport path R5 and discharged to the discharge tray 7 along the discharge trajectory T1.

[0024] Here, the discharge tray 7 onto which the media transported along the discharge trajectory T1 is discharged can be in a stored state as shown in Fig. 2 or an open state (not shown) by rotating about a rotation shaft 7a. When the flap 33 is in the state shown by the imaginary line and reference symbol 33-1 in Fig. 2, the media is guided to the face-up transport path R5 and discharged from the discharge tray 7 along the discharge trajectory T1. At this time, the discharge tray 7 is in an open state (not shown).

[0025] Of the medium transport paths along which the medium is transported inside the printing device 1, a medium feed path along which the medium is transported to the pair of registration rollers 17 located upstream of the print head 8 will be described with reference to FIG.

[0026] The medium cassette 10A is detachably attached to the device main body 2A. The medium cassette 10A has a hopper 11. The hopper 11 swings around an axis 11a, so that the medium stored in the medium cassette 10A approaches and separates from the feed roller 12 that is driven to rotate by a motor (not shown). The medium sent out from the medium cassette 10A by the feed roller 12 is separated by passing through a nip position by the separation roller pair 13, and is transported by receiving a feeding force from the transport roller pair 14 to reach the registration roller pair 17. This prevents the so-called double feeding, in which the media stored in the medium cassette 10A are transported in a state where multiple media are overlapped. Here, although not shown in FIG. 2, the additional units 2B and 2C located below the device main body 2A also have the feed roller 12 and the separation roller pair 13, and the media sent out from each of the medium cassettes 10B and 10C is transported by receiving a feeding force from the transport roller pair 14 shown in FIG. 2 to reach the registration roller pair 17.

[0027] The feeding unit 35 also has a manual feed tray 41 inside the opening / closing cover 6. The manual feed tray 41 rotates around a swing shaft 41a and can be opened and closed together with the opening / closing cover 6. When the opening / closing cover 6 rotates around the swing shaft 6a and the manual feed tray 41 rotates around the swing shaft 41a and opens, the manual feed tray 41 enters an open state (not shown) and the user can manually feed the medium. A feed roller 15 and a separation roller 16 are provided along a feed trajectory S3 along which the medium is transported from the manual feed tray 41. The medium set in the manual feed tray 41 is transported by the rotation of the feed roller 15 and the separation roller 16 and reaches the pair of registration rollers 17.

[0028] Next, of the medium transport path along which the medium is transported inside the printing device 1, a medium discharge path downstream of the pair of registration rollers 17 will be described with reference to Fig. 3. Fig. 3 is a diagram showing an example of the medium discharge path downstream of the pair of registration rollers 17. Note that the following description will be given of the case where the medium is discharged to the discharge tray 4 via the face-down transport path R4.

[0029] In describing an example of a medium discharge path, first, a number of rollers provided in the medium discharge path will be described. As shown in Fig. 3, the medium discharge path is provided with transport roller pairs 20-24, 26-29 and discharge roller pair 25. The transport roller pairs 20-24, 26-29 are roller pairs that transport the medium along the medium discharge path, and the discharge roller pair 25 is a roller pair that discharges the medium transported along the medium discharge path onto the discharge tray 4.

[0030] In FIG. 3, the roller on one side of each roller pair other than the registration roller pair 17 and the conveying roller pair 29 is illustrated as F, and the roller on the other side is illustrated as G. The roller F is a driving roller driven by a motor (not shown), and is, for example, a rubber roller provided in a plurality of locations at appropriate intervals in the width direction of the medium. On the other hand, the roller G is a driven roller that can nip the medium between the roller F by a biasing means (not shown), and is rotated in contact with the medium, and is provided as a pair with the roller F at an appropriate interval in the width direction of the medium. This roller G is a serrated roller having a plurality of teeth on its outer periphery, and by making point contact with the printing surface of the medium, the risk of whiteout or transfer of the image printed on the medium is reduced. The roller G may be provided at an appropriate position on the medium conveying path other than constituting the conveying roller pairs 20 to 24, 26 to 28, and the discharge roller pair 25, and in this case, the roller G may be provided on the side that contacts the nearest printing surface.

[0031] The registration roller pair 17 and the transport roller pair 29 are different in configuration from the transport roller pairs 20 to 24, 26 to 28, and the discharge roller pair 25. Specifically, the transport roller pair 29 includes a driving roller 29a that is driven to rotate, and a driven roller 29b that is pressed against the driving roller 29a and can rotate by the driving roller. Of these, the driven roller 29b is a resin roller with a smooth outer circumferential surface. On the other hand, the registration roller pair 17 includes a driving roller 17a that is driven to rotate, and a driven roller 17b that is pressed against the driving roller 17a by a biasing means (not shown) and can rotate by the driving roller. Of these, the driving roller 17a is a roller having fine irregularities on the outer circumferential surface, and the driven roller 17b is a resin roller with a smooth outer circumferential surface.

[0032] The recording transport path R1 is a medium transport path that passes below the print head 8 that prints on the medium, and extends from the upstream side to the downstream side of the print head 8. For convenience of explanation, in this embodiment, the recording transport path R1 will be described as roughly ranging from position M1 to position M2 shown in Fig. 3. In this recording transport path R1, the medium is transported by receiving a feed force from the pair of registration rollers 17 and the belt unit 18, and as the medium passes below the print head 8, the print head 8 executes a printing process on the medium.

[0033] The switchback transport path R2 is a medium transport path that connects with the recording transport path R1, and when the medium that has passed under the print head 8 is fed, the switchback transport path R2 switches back and transports the fed medium in the opposite direction to the direction in which it was fed. This type of switchback transport path R2 is located inside a curved face-down transport path R4, which will be described later. For the sake of convenience, in this embodiment, the switchback transport path R2 will be described as being generally in the range to the left of position M3 shown in FIG. 3. In this switchback transport path R2, the medium is transported by receiving a feeding force from the transport roller pair 26.

[0034] The reverse transport path R3 is a medium transport path that connects to the switchback transport path R2, and after the medium has been switched back on the switchback transport path R2, it is detouring so as to pass above the print head 8, and then merges with the recording transport path R1 upstream of the print head 8. For the sake of convenience, in this embodiment, the reverse transport path R3 will be described as roughly ranging from position M3 to position M4 shown in Figure 3. In this reverse transport path R3, the medium is transported by receiving a feed force from transport roller pairs 27, 28, and 29.

[0035] The face-down transport path R4 is a medium transport path that connects to the recording transport path R1, and is a path that curves the medium that has passed under the print head 8 so that the surface facing the print head 8 is inward, and discharges the medium in an inverted state onto the discharge tray 4. For convenience, in this embodiment, the face-down transport path R4 will be described as being generally in the range to the left of position M2 shown in FIG. 3. In this face-down transport path R4, the medium is transported by receiving a feeding force from transport roller pairs 20-24 and discharge roller pair 25.

[0036] Flaps 31 and 32 are provided at the connection points of the recording transport path R1, the switchback transport path R2, the reversing transport path R3, the face-down transport path R4, and the face-up transport path R5 as path switching members for switching the medium transport path. The flap 31 can be swung around a swing fulcrum 31a by receiving a driving force from a driving means (not shown). The flap 32 is provided so as to be engageable with the flap 31 via an engagement portion (not shown), and swings around a swing fulcrum 32a in response to the swing of the flap 31. The flaps 31 and 32 set the medium transport path along which the medium is transported.

[0037] Next, the configuration of the periphery of the recording transport path R1 will be described with reference to Fig. 4. Fig. 4 is a diagram showing an example of the structure of the periphery of the recording transport path R1. In the printing device 1, when the medium passes under the print head 8 on the recording transport path R1, the print head 8 executes a printing process on the medium. In other words, the recording transport path R1 corresponds to the area of ​​the medium transport path where the printing process is executed on the medium.

[0038] As shown in FIG. 4, the recording transport path R1 has a pair of registration rollers 17 for transporting the medium, and a belt unit 18. The belt unit 18 includes a driving pulley 18a, a driven pulley 18b, and a transport belt 18c. The transport belt 18c is an endless belt in which a charging material for storing electric charges is contained or applied to a base material made of urethane, rubber, or the like. The transport belt 18c is wound around the driving pulley 18a on the upstream side of the recording transport path R1, and is wound around the driven pulley 18b on the downstream side of the recording transport path R1. A predetermined tension is applied to the transport belt 18c by a tensioner (not shown). The drive pulley 18a is driven to rotate by a motor 37, so that the transport belt 18c is driven to rotate, and the medium supported by the transport belt 18c is transported.

[0039] Further, support plates 45 and 46 are provided on the inner side of the conveyor belt 18c. The conveyor belt 18c is provided in a state in which its inward bending is restricted by these support plates 45 and 46. The support plates 45 and 46 are formed of a conductive material such as a metal and are grounded.

[0040] A charging roller 44 is provided at a position facing the drive pulley 18a with the conveyor belt 18c interposed therebetween. The charging roller 44 is in contact with the outer surface of the conveyor belt 18c. The charging roller 44 is rotated in response to the operation of the conveyor belt 18c. A high DC voltage is supplied to the charging roller 44 from a power supply device 49, which will be described later. As a result, an electric charge is supplied to the conveyor belt 18c in contact with the charging roller 44 via the charging roller 44, and as a result, an electric charge is stored in the conveyor belt 18c.

[0041] The medium supported by the conveyor belt 18c is attracted to the belt unit 18 by the electric charge accumulated via the charging roller 44. In the following description, the surface of the belt unit 18 to which the medium is attracted, that is, the outer surface of the conveyor belt 18c facing the print head 8, may be referred to as the attraction surface 18d.

[0042] In addition, a driven roller 19a is provided above the driving pulley 18a with the conveyor belt 18c sandwiched therebetween. In addition, a driven roller 19b is provided above the driven pulley 18b with the conveyor belt 18c sandwiched therebetween. The medium conveyed by the conveyor belt 18c is pressed against the conveyor belt 18c by the driven rollers 19a and 19b. As a result, the medium is in close contact with the adsorption surface 18d. The driven rollers 19a and 19b are made of a conductive material such as metal and are grounded.

[0043] A charge removing brush 43 that contacts the medium is provided upstream of the print head 8. This charge removing brush 43 removes the charge on the top surface of the medium and the charge on the outer surface, i.e., the adsorption surface 18d, of the conveyor belt 18c. Specifically, when the charge is accumulated on the adsorption surface 18d of the conveyor belt 18c by the charging roller 44, a charge of the opposite polarity to that of the adsorption surface 18d is generated on the surface of the medium that contacts the adsorption surface 18d. Therefore, on the opposite surface of the medium, which is the printing surface on which the print head 8 executes the printing process, a charge of the opposite polarity to that of the surface where the medium and the adsorption surface 18d contact is generated. The charge removing brush 43 removes the charge accumulated on the printing surface of the medium. As a result, only the charge on the surface of the medium that contacts the conveyor belt 18c remains. As a result, the medium is adsorbed to the adsorption surface 18d. Such a charge removing brush 43 may be made of any material that can remove charge from the medium and the conveyor belt 18c, and may be made of, for example, a resin material such as conductive nylon.

[0044] Further, a heater 48 is provided downstream of the print head 8. The heater 48 heats the medium on which printing has been performed by the print head 8, thereby fixing the image formed on the medium to the medium. The heater 48 may be provided on the upstream side as well as the downstream side of the print head 8, or may be located inside the conveyor belt 18c. In other words, the printing device 1 includes a heater 48 that heats the medium. The heater 48 is an example of a heating means.

[0045] Further, a cleaning blade 47 is provided below the belt unit 18 so as to sandwich the conveyor belt 18c between the cleaning blade 47 and the support plate 46. The cleaning blade 47 removes ink, foreign matter, and the like adhering to the adsorption surface 18d by wiping the adsorption surface 18d of the conveyor belt 18c.

[0046] As described above, in the printing device 1 of this embodiment, the medium stored in the medium cassettes 10A, 10B, 10C or the medium supplied from the feeding unit 35 is transported along the medium transport path. Then, when the medium is transported to the recording transport path R1, the print head 8 executes a printing process on the medium. The medium on which the printing process has been executed is then discharged from the discharge tray 4 via the face-down transport path R4.

[0047] 2. Functional configuration of the printing device Next, a description will be given of the functional configuration of the printing device 1. Fig. 5 is a diagram showing an example of the functional configuration of the printing device 1. As shown in Fig. 5, the printing device 1 includes a control unit 100, a printing unit 200, a drive signal output unit 210, a transport unit 300, a voltage supply unit 400, a detection unit 500, a discrimination unit 600, an interface unit 700, and a machine learning unit 800.

[0048] The printing device 1 executes a printing process on a medium based on operation information input by a user operating the interface unit 700, or image data supplied by a user operating an external device such as a host computer that is communicatively connected via the interface unit 700. That is, the interface unit 700 functions as a user interface that accepts operation information from a user operating the printing device 1. Such an interface unit 700 includes the above-mentioned operation panel 5, a communication port that communicatively connects the printing device 1 to the external device, and the like. The interface unit 700 then generates an operation information signal UI that includes operation information and image data based on the user's operation, and outputs the operation information signal UI to the control unit 100.

[0049] Based on the input operation information signal UI, the control unit 100 outputs various control signals to control the printing unit 200, the drive signal output unit 210, the transport unit 300, the voltage supply unit 400, the detection unit 500, the discrimination unit 600, and the interface unit 700.

[0050] Specifically, the control unit 100 generates a print control data signal DATA based on the operation information signal UI and outputs it to the printing unit 200, and also generates a base drive signal dDRV and outputs it to the drive signal output unit 210. The drive signal output unit 210 generates a drive signal DRV for driving a drive element that is driven when the printing unit 200 forms an image on a medium based on the input base drive signal dDRV, and outputs it to the printing unit 200.

[0051] Here, in the case where the printing device 1 is a so-called inkjet printer that forms an image on a medium by ejecting ink onto the medium, the driving element driven by the driving signal DRV can be, for example, a piezoelectric element that deforms in response to the driving signal DRV and, by changing the internal volume of the cavity filled with ink, causes ink to be ejected from the nozzle, or a heating element that generates heat in response to the driving signal DRV and, by generating heat, changes the internal pressure of the cavity filled with ink, causes ink to be ejected from the nozzle.

[0052] The printing unit 200 also includes the print head 8 described above. The printing unit 200 forms dots of a desired size on a medium based on a print control data signal DATA input from the control unit 100 and a drive signal DRV input from the drive signal output unit 210. Specifically, the print head 8 of the printing unit 200 supplies a drive signal DRV to a drive element at a timing based on the print control data signal DATA, thereby ejecting ink onto the medium at a desired timing defined by the print control data signal DATA. The printing unit 200 is an example of a printing means that prints on a medium such as lime plaster paper containing calcium carbonate.

[0053] The control unit 100 also generates a transport control signal TC for controlling the transport of the medium, and outputs it to the transport unit 300. The transport unit 300 transports the medium along a predetermined medium transport path based on the input transport control signal TC. That is, the transport unit 300 includes the feed roller 12 and separation roller pair 13 constituting the medium feed path described above, the transport roller pairs 20-24, 26-29 constituting the medium discharge path, the discharge roller pair 25, the registration roller pair 17, and the belt unit 18. Based on the transport control signal TC input from the control unit 100, the transport unit 300 drives various motors including the motor 37 described above to drive various rollers including the transport roller pairs 20-24, 26-29, the discharge roller pair 25, and the registration roller pair 17, and also drives the transport belt 18c included in the belt unit 18 to rotate. As a result, the transport unit 300 transports the medium along the medium transport path. The transport unit 300 that rotates the transport belt 18c that constitutes at least a part of the medium transport path along which the medium is transported is an example of a transport means.

[0054] The transport unit 300 also generates a position information signal PI indicating the transport position of the medium and the rotational position of the transport belt 18c, and outputs it to the control unit 100. The control unit 100 generates a print control data signal DATA corresponding to the transport position of the medium based on the position information signal PI input from the transport unit 300, and outputs it to the printing unit 200. This allows the printing unit 200 to eject ink onto the medium at a timing synchronized with the transport of the medium. As a result, the desired ink lands on the medium, and the desired image is formed on the medium.

[0055] Here, the position information signal PI output by the transport unit 300 may be a signal generated based on, for example, encoder information output by an encoder or the like, or may be a signal generated based on sensor detection information detected by a sensor element (not shown) provided at a predetermined position of the transport unit 300. Furthermore, the position information signal PI output by the transport unit 300 may individually include a position information signal PI indicating the transport position of the medium and a position information signal PI indicating the rotational position of the transport belt 18c.

[0056] The control unit 100 also outputs a voltage value control signal VC to the voltage supply unit 400. The voltage supply unit 400 generates a charge control voltage CV having a voltage value defined by the input voltage value control signal VC, and supplies the charge control voltage CV to the charging roller 44 of the transport unit 300. As a result, a charge according to the charge control voltage CV is supplied to the transport belt 18c via the charging roller 44, and a charge according to the charge control voltage CV is stored in the transport belt 18c. That is, the charge control voltage CV corresponds to a high-voltage DC voltage that is the basis of the charge stored in the transport belt 18c described above, and the voltage supply unit 400 includes a power supply device 49 that outputs a high-voltage DC voltage. The charge control voltage CV supplied to the charging roller 44 that charges the transport belt 18c is an example of a charge voltage, and the voltage supply unit 400 that supplies the charge control voltage CV to the charging roller 44 is an example of a voltage supply means.

[0057] The transport unit 300 generates a charge detection voltage CD according to the amount of charge stored in the transport belt 18c based on the charge control voltage CV output by the voltage supply unit 400, and outputs the charge detection voltage CD to the detection unit 500.

[0058] The detection unit 500 detects whether the amount of charge on the conveyor belt 18c is normal or not, that is, whether the voltage value on the conveyor belt 18c is normal or not, based on the input charge detection voltage CD, and generates a charge voltage determination signal CE indicating the detection result. In other words, the detection unit 500 detects whether a charging abnormality occurs on the conveyor belt 18c. Then, the detection unit 500 outputs the charge voltage determination signal CE indicating whether a charging abnormality occurs on the conveyor belt 18c to the control unit 100, the discrimination unit 600, and the machine learning unit 800.

[0059] Here, a specific example of the configuration of the detection unit 500 will be described with reference to Fig. 6. Fig. 6 is a diagram showing the functional configuration of the detection unit 500. As shown in Fig. 6, the detection unit 500 has a recording circuit 510, a threshold correction circuit 520, and a comparison circuit 530.

[0060] The recording circuit 510 records threshold information Cth for detecting whether or not a charging abnormality occurs in the conveyor belt 18c in the detection unit 500. The threshold information Cth recorded in the recording circuit 510 is read out by the threshold correction circuit 520. The threshold correction circuit 520 also receives threshold correction information HI output from the control unit 100. The threshold correction circuit 520 corrects the threshold information Cth read out from the recording circuit 510 based on the threshold correction information HI input from the control unit 100, and outputs corrected threshold information HCth to the comparison circuit 530 as the corrected threshold information Cth. That is, the threshold correction circuit 520 corrects the threshold information Cth.

[0061] The comparison circuit 530 detects whether or not a charging abnormality has occurred in the conveyor belt 18c by comparing the corrected threshold information HCth, which corresponds to the corrected threshold information Cth, with the charge detection voltage CD, which indicates the amount of charge charged on the conveyor belt 18c of the conveyor unit 300. Then, the comparison circuit 530 outputs a charging voltage determination signal CE according to the comparison result to the control unit 100, the discrimination unit 600, and the machine learning unit 800.

[0062] Here, in this embodiment, the comparison circuit 530 outputs a high-level charge voltage determination signal CE indicating that a charge abnormality occurs in the conveyor belt 18c when the charge detection voltage CD exceeds the correction threshold information HCth, and outputs a low-level charge voltage determination signal CE indicating that a charge abnormality does not occur in the conveyor belt 18c when the charge detection voltage CD is below the correction threshold information HCth. The comparison circuit 530 may determine that a charge abnormality occurs in the conveyor belt 18c when the charge detection voltage CD is below the correction threshold information HCth, and may determine that a charge abnormality does not occur in the conveyor belt 18c when the charge detection voltage CD exceeds the correction threshold information HCth. Furthermore, the comparison circuit 530 may output a low-level charge voltage determination signal CE when a charge abnormality occurs in the conveyor belt 18c, and output a high-level charge voltage determination signal CE when a charge abnormality does not occur in the conveyor belt 18c.

[0063] Here, the detection unit 500 which detects whether or not a charging abnormality has occurred in the conveying belt 18c is an example of a detection means, the recording circuit 510 included in the detection unit 500 is an example of a recording section, the threshold correction circuit 520 is an example of a threshold correction section, and the comparison circuit 530 is an example of a comparison section.

[0064] 5, the machine learning unit 800 receives as input a position information signal PI indicating the rotational position of the conveyor belt 18c, a charged voltage determination signal CE indicating the detection result of the detection unit 500, and a discrimination result signal RD indicating the discrimination result in the discrimination unit 600, which will be described later. The machine learning unit 800 then machine-learns discrimination conditions in the discrimination unit 600 based on a learning model that associates the amount of rotation of the conveyor belt 18c calculated from the input position information signal PI with the charged voltage determination signal CE indicating the detection result of the detection unit 500, and generates a discrimination condition signal JC according to the learning result and outputs it to the discrimination unit 600.

[0065] FIG. 7 is a diagram showing an example of the configuration of the machine learning unit 800. As shown in FIG. 7, the machine learning unit 800 includes a learning model holding unit 810 and a learning model update unit 820. The position information signal PI and the charged voltage determination signal CE are input to the learning model holding unit 810. The learning model holding unit 810 holds a learning model in which the rotation amount of the conveyor belt 18c calculated from the position information signal PI and the charged voltage determination signal CE output by the detection unit 500 are associated with each other. The learning model holding unit 810 generates a discrimination condition signal JC based on the rotation amount of the conveyor belt 18c calculated from the input position information signal PI, the charged voltage determination signal CE indicating the detection result of the detection unit 500, and the held learning model, and outputs the discrimination condition signal JC to the discrimination unit 600.

[0066] The position information signal PI, the electrostatic voltage determination signal CE, and the discrimination result signal RD are input to the learning model update unit 820. Then, the learning model update unit 820 generates learning model update information SU based on the position information signal PI, the electrostatic voltage determination signal CE, and the discrimination result signal RD, and outputs it to the learning model holding unit 810. The learning model holding unit 810 performs machine learning based on the learning model it holds and the learning model update information SU input from the learning model update unit 820, thereby generating a new learning model and updating the learning model it holds.

[0067] As described above, the machine learning unit 800 performs machine learning of the discrimination conditions in the discrimination unit 600 based on a learning model that associates the amount of rotation of the conveyor belt 18c with the detection result of the detection unit 500, and generates a discrimination condition signal JC based on the learning model generated by machine learning, the amount of rotation of the conveyor belt 18c calculated from the input position information signal PI, and the charged voltage determination signal CE indicating the detection result of the detection unit 500, and outputs it to the discrimination unit 600. Here, the machine learning unit 800 is an example of a machine learning means.

[0068] The discrimination unit 600 receives the charge voltage determination signal CE output by the detection unit 500, the position information signal PI indicating the rotational position of the conveyor belt 18c output by the conveyor unit 300, and the discrimination condition signal JC output by the machine learning unit 800. The discrimination unit 600 then determines whether or not a charging abnormality has occurred in the conveyor belt 18c based on the charge voltage determination signal CE, the position information signal PI, and the discrimination condition signal JC, and if a charging abnormality has occurred in the conveyor belt 18c, determines the cause of the charging abnormality occurring in the conveyor belt 18c. The discrimination unit 600 then generates a discrimination result signal RD indicating the discrimination result and outputs it to the control unit 100 and the machine learning unit 800.

[0069] Here, we will explain the causes of the charging abnormality that may occur in the conveyor belt 18c, which is identified by the identification unit 600. The charging abnormality that may occur in the conveyor belt 18c includes charging abnormality caused by an abnormality in the voltage supply unit 400 that outputs a charging control voltage CV for storing charge in the conveyor belt 18c, and charging abnormality caused by a scratch or the like occurring in the conveyor belt 18c to which the charge is applied.

[0070] When a charging abnormality occurs due to an abnormality in the voltage supply unit 400, the abnormality may spread to each component of the printing device 1 because the voltage supply unit 400 outputs a high DC voltage. Therefore, the printing device 1 stops the printing process in the printing unit 200. On the other hand, when a charging abnormality occurs due to a scratch or the like on the charging conveyor belt 18c, although there is a possibility that the charge distribution stored on the conveyor belt 18c may vary, the abnormality is unlikely to spread to each component of the printing device 1, and therefore, in consideration of the convenience of the user, it is preferable that the printing unit 200 continues the printing process. In other words, the printing device 1 is required to change the control depending on the cause of the charging abnormality that occurred on the conveyor belt 18c.

[0071] Therefore, in the printing device 1 of this embodiment, the discrimination unit 600 discriminates whether or not a charging abnormality has occurred in the conveyor belt 18c based on the charging voltage determination signal CE, the position information signal PI, and the discrimination condition signal JC, and, if a charging abnormality has occurred in the conveyor belt 18c, discriminates whether the cause of the charging abnormality is a charging abnormality caused by an abnormality in the voltage supply unit 400, or a charging abnormality caused by a scratch or the like on the conveyor belt 18c. Then, based on the discrimination result by the discrimination unit 600, the control unit 100 controls each component of the printing device 1, thereby reducing the risk of the stability of the operation of the printing device 1 being reduced due to the charging abnormality occurring in the conveyor belt 18c.

[0072] In particular, in a printing device 1 that prints on a medium containing calcium carbonate, such as the printing device 1 of this embodiment, and that uses plaster paper coated with plaster as the medium, calcium carbonate and the like contained in the medium accumulates inside the printing device 1 as the printing process continues for a long period of time, and the accumulated calcium carbonate reacts with moisture in the air and moisture contained in ink, which is an example of a printing material, causing the calcium carbonate to solidify and adhere to the conveyor belt 18c. The adhered calcium carbonate is then sandwiched between the conveyor belt 18c and various rollers, damaging the conveyor belt 18c. In other words, in a printing device 1 that prints on a medium containing calcium carbonate, and that uses plaster paper coated with plaster as the medium, there is an increased risk of damage such as scratches on the conveyor belt 18c, and as a result, there is an increased risk of the printing process in the printing device 1 being stopped unintentionally.

[0073] In response to such a problem, the discrimination unit 600 discriminates whether the cause of the charge abnormality occurring in the conveyor belt 18c is an abnormality in the voltage supply unit 400, an abnormality in the conveyor belt 18c, or an abnormality in both the voltage supply unit 400 and the conveyor belt 18c based on the discrimination condition signal JC, the position information signal PI, and the charge voltage judgment signal CE, and the control unit 100 controls the operation of the printing device 1 according to the discrimination result of the discrimination unit 600, thereby reducing the risk that the abnormality caused by the charge abnormality in the conveyor belt 18c will affect each component of the printing device 1 and reducing the risk of the printing process being stopped unintentionally. In other words, the stability of the operation of the printing device 1 is improved. A specific example of the discrimination operation in the discrimination unit 600 will be described later. Here, the discrimination unit 600 is an example of a discrimination means.

[0074] Here, an example of the operation of the control unit 100 that controls the operation of each component of the printing device 1 based on the discrimination result signal RD input from the discrimination unit 600 will be described.

[0075] When the discrimination result signal RD input to the control unit 100 indicates that the charge abnormality occurring on the conveyor belt 18c is caused by an abnormality in the voltage supply unit 400, the control unit 100 generates a print control data signal DATA for stopping the printing process and outputs it to the printing unit 200. This causes the printing unit 200 to stop the printing process. In other words, when the discrimination unit 600 determines that the charge abnormality occurring on the conveyor belt 18c is caused by an abnormality in the voltage supply unit 400, the printing unit 200 stops printing on the medium.

[0076] The voltage supply unit 400 generates a high DC voltage as the charge control voltage CV and supplies it to the conveyor belt 18c via the charging roller 44. If the printing process in the printing unit 200 is continued in a state in which an abnormality occurs in the voltage supply unit 400 that generates such a high DC voltage, the high charge control voltage CV output by the voltage supply unit 400 may cause the abnormality of the voltage supply unit 400 to spread to components of the printing device 1 that are operating normally. To address this problem, if an abnormality occurs in the voltage supply unit 400 that outputs a high DC voltage, the control unit 100 stops the printing process in the printing unit 200, thereby reducing the risk that the abnormality caused in the voltage supply unit 400 will spread to other components of the printing device 1.

[0077] Furthermore, when the discrimination result signal RD input to the control unit 100 indicates that the charge abnormality occurring in the conveyor belt 18c is caused by an abnormality in the conveyor belt 18c, the control unit 100 generates an operation unit control signal UC for displaying warning information indicating that an abnormality has occurred in the conveyor belt 18c, and outputs it to the interface unit 700. This causes the display unit of the operation panel 5 included in the interface unit 700 to display warning information indicating that an abnormality has occurred in the conveyor belt 18c. That is, when the discrimination unit 600 determines that the charge abnormality occurring in the conveyor belt 18c is caused by an abnormality in the conveyor belt 18c, the control unit 100 notifies the user of the warning information via the display unit of the operation panel 5 included in the interface unit 700. Note that the notification unit that notifies the user of the warning information may be a display unit such as a liquid crystal panel or a touch panel, or an audio output unit such as a speaker that notifies the user of the warning information by voice.

[0078] Furthermore, as described above, when the charge abnormality occurring in the conveyor belt 18c is caused by an abnormality in the conveyor belt 18c, there is a low possibility that the abnormality will spread to other components of the printing device 1, compared to when an abnormality occurs in the voltage supply unit 400. Therefore, from the viewpoint of not impairing user convenience, when the charge abnormality occurring in the conveyor belt 18c is caused by an abnormality in the conveyor belt 18c, it is preferable that the printing device 1 continues the printing process in the printing unit 200.

[0079] Therefore, when the discrimination unit 600 discriminates that the charge abnormality occurring in the conveyor belt 18c is caused by an abnormality in the conveyor belt 18c, the control unit 100 generates and outputs an operation unit control signal UC for notifying the user of warning information that an abnormality has occurred in the conveyor belt 18c, so that the user can replace the conveyor belt 18c at any timing that does not impede the printing process. In other words, the risk of the printing process in the printer 1 being unintentionally stopped due to an abnormality in the conveyor belt 18c can be reduced, and the risk of impeding the convenience of the user can be reduced.

[0080] Furthermore, when the input discrimination result signal RD includes information that a charging abnormality has occurred in the conveyor belt 18c, the control unit 100 may generate a voltage value control signal VC for changing the voltage value of the charging control voltage CV and output it to the voltage supply unit 400. That is, the voltage value of the charging voltage to be applied to the conveyor belt 18c may be adjusted according to the discrimination result in the discrimination unit 600.

[0081] The control unit 100 controls the voltage value of the charge control voltage CV supplied to the charging roller 44 according to the discrimination result of the discrimination unit 600, so that the charging voltage charged to the conveyor belt 18c can be adjusted to a potential at which the detection unit 500 does not detect a charging abnormality. This makes it possible to temporarily eliminate the charging abnormality occurring in the conveyor belt 18c. As a result, when the printing unit 200 continues to execute the printing process, the risk of warning information being continuously notified is reduced, and the cause of the charging abnormality can be removed at any timing by the user. This reduces the risk of the printing process being stopped unintentionally, which impairs the convenience of the user.

[0082] In this case, the control unit 100 may notify the user that the charging voltage of the conveyor belt 18c is being adjusted via a notification unit such as a display unit included in the operation panel 5 of the interface unit 700. This allows the user to perform various measures to eliminate the charging abnormality occurring in the conveyor belt 18c at the optimal timing without forgetting to perform the measures.

[0083] Furthermore, when the discrimination result signal RD input to the control unit 100 indicates that the charge abnormality occurring in the conveyor belt 18c is caused by an abnormality in the conveyor belt 18c, the control unit 100 may generate threshold correction information HI for correcting the threshold information Cth so as to alleviate detection of the charge abnormality, and output the threshold correction information HI to the threshold correction circuit 520 of the detection unit 500. That is, when the discrimination unit 600 discriminates that the charge abnormality occurring in the conveyor belt 18c is caused by an abnormality in the conveyor belt 18c, the threshold correction circuit 520 may correct the threshold information Cth so as to alleviate detection of the charge abnormality.

[0084] This reduces the inconvenience caused to the user by the continuous notification of warning information when the charge abnormality occurring in the conveyor belt 18c is due to an abnormality in the conveyor belt 18c. In other words, the convenience of the user who uses the printing device 1 can be further improved. Note that, when the threshold correction circuit 520 corrects the threshold information Cth so as to ease the detection of the charge abnormality, the control unit 100 may periodically notify the user of warning information prompting replacement of the conveyor belt 18c via the interface unit 700. This reduces the risk of the conveyor belt 18c with the charge abnormality being continuously used.

[0085] In addition, when the conveyor belt 18c is replaced by the user, the control unit 100 initializes the correction value used by the threshold correction circuit 520 to correct the threshold information Cth, and also initializes the learning result obtained by the machine learning unit 800 through machine learning.

[0086] When the conveyor belt 18c is replaced, the damage that occurred in the conveyor belt 18c disappears, and as a result, it is presumed that the charging abnormality caused by the conveyor belt 18c is improved. Therefore, by initializing the correction value of the threshold information Cth by the threshold correction circuit 520 and the learning result obtained by machine learning by the machine learning unit 800 due to the replacement of the conveyor belt 18c, it is possible to detect and determine the presence or absence of a charging abnormality in the replaced conveyor belt 18c regardless of the state of the conveyor belt 18c before replacement, and therefore it is possible to improve the detection accuracy of the charging abnormality.

[0087] 3. Identification of the cause of charging abnormality by the judgment unit Next, a method for determining whether or not a charging abnormality has occurred in the conveying belt 18c in the determination unit 600, and a method for determining whether the charging abnormality has been caused by an abnormality in the voltage supply unit 400 or an abnormality in the conveying belt 18c if a charging abnormality has occurred in the conveying belt 18c will be described.

[0088] In describing the discrimination method in the discrimination unit 600, an example of the presence or absence of a charging abnormality in the conveyor belt 18c detected by the detection unit 500 and a charging voltage determination signal CE for each cause of the charging abnormality will be described with reference to Figures 8 to 10. Note that Figures 8 to 10 illustrate the charging detection voltage CD output from the conveyor unit 300 in the region between arbitrary positions p1 and p2 on the conveyor belt 18c.

[0089] 8 is a diagram showing a case where no charging abnormality occurs in the region between arbitrary positions p1 and p2 on the conveyor belt 18c. As shown in FIG. 8, when no charging abnormality occurs on the conveyor belt 18c, the charging detection voltage CD input to the detection unit 500 is lower in potential than the correction threshold information HCth. As a result, the comparison circuit 530 included in the detection unit 500 outputs a low-level charging voltage determination signal CE indicating that no charging abnormality occurs on the conveyor belt 18c.

[0090] FIG. 9 is a diagram showing a case where a charging abnormality occurs in the region between arbitrary positions p1 and p2 on the conveyor belt 18c due to an abnormality in the voltage supply unit 400. When an abnormality occurs in the voltage supply unit 400, the voltage supply unit 400 outputs a charging control voltage CV with a higher potential than when it is normal. Therefore, the amount of charge stored in the region between arbitrary positions p1 and p2 on the conveyor belt 18c also increases, and as a result, as shown in FIG. 9, the potential of the charging detection voltage CD input to the detection unit 500 exceeds the correction threshold information HCth. As a result, the comparison circuit 530 included in the detection unit 500 outputs a high-level charging voltage determination signal CE indicating that a charging abnormality occurs in the conveyor belt 18c. That is, when an abnormality occurs in the voltage supply unit 400, in the region between arbitrary positions p1 and p2 on the conveyor belt 18c, the detection unit 500 outputs a charging voltage determination signal CE that continues to be at a high level.

[0091] 10 is a diagram showing a case where a charging abnormality occurs due to an abnormality of the conveyor belt 18c in an area between arbitrary positions p1 and p2 on the conveyor belt 18c. As shown in FIG. 10, when scratches Sc1 and Sc2 occur on the surface of the conveyor belt 18c as an abnormality of the conveyor belt 18c, the surface impedance of the conveyor belt 18c changes due to the scratches Sc1 and Sc2, and as a result, the amount of electric charge stored varies between the area of ​​the conveyor belt 18c where the scratches occur and the area of ​​the conveyor belt 18c where the scratches do not occur. As a result, the pulse voltage Se1 is superimposed on the charging detection voltage CD output from the conveyor unit 300 in the area of ​​the conveyor belt 18c where the scratches Sc1 occur, and the pulse voltage Se2 is superimposed on the charging detection voltage CD output from the conveyor unit 300 in the area of ​​the conveyor belt 18c where the scratches Sc2 occur. That is, when the conveyor belt 18c has an abnormality such as scratches Sc1 and Sc2, the conveyor unit 300 outputs a charge detection voltage CD obtained by superimposing a pulse voltage Se1 corresponding to the scratch Sc1 and a pulse voltage Se2 corresponding to the scratch Sc2 on the charge detection voltage CD when no charge abnormality occurs as shown in Fig. 8. As a result, the comparator circuit 530 included in the detection unit 500 outputs a charge voltage determination signal CE that is at a high level only in the area corresponding to the scratches Sc1 and Sc2 in the area between any positions p1 and p2 on the conveyor belt 18c.

[0092] As described above, in the printing device 1 of this embodiment, whether or not a charging abnormality has occurred in the conveying belt 18c can be determined based on whether or not the charging detection voltage CD input to the detection unit 500 exceeds the correction threshold information HCth in the region from position p1 to position p2, which is a predetermined range of the conveying belt 18c. Also, if a charging abnormality has occurred in the conveying belt 18c, whether the charging abnormality is caused by an abnormality in the voltage supply unit 400 or an abnormality in the conveying belt 18c can be determined based on how long a period is included during which the charging detection voltage CD input to the detection unit 500 does not exceed the correction threshold information HCth in the region from position p1 to position p2, which is a predetermined range of the conveying belt 18c.

[0093] Specifically, the discrimination unit 600 grasps the position of the rotating conveyor belt 18c based on the position information signal PI input from the conveying unit 300, and discriminates whether the charge detection voltage CD exceeds the correction threshold information HCth depending on whether the charge voltage determination signal CE input from the detection unit 500 is at high level or low level. Then, based on the position information signal PI, during the period in which the conveyor belt 18c rotates within the range between positions p1 and p2, the discrimination unit 600 discriminates whether the charge abnormality occurring in the conveyor belt 18c is caused by an abnormality in the conveyor belt 18c or an abnormality in the voltage supply unit 400 depending on the period in which the charge voltage determination signal CE at a high level is input and the period in which the charge voltage determination signal CE at a low level is input.

[0094] In this case, the conveyor belt 18c rotates in response to the printing process of the printing device 1. Therefore, the number and size of damage, including scratches Sc1 and Sc2, occurring on the conveyor belt 18c also change. That is, during the period during which the conveyor belt 18c rotates within the range of the area between positions p1 and p2, the period during which a high-level charged voltage determination signal CE is input and the period during which a low-level charged voltage determination signal CE is input may change. In the printing device 1 of this embodiment, the machine learning unit 800 performs machine learning of such a changing state of damage occurring on the conveyor belt 18c, and the machine learning unit 800 generates and outputs a threshold value Nth and a threshold value Eth as a discrimination condition signal JC according to the results of the machine learning, thereby improving the discrimination accuracy of the discrimination unit 600.

[0095] Here, an example of a specific method for determining the cause of the charging abnormality in the determination unit 600 will be described with reference to FIG. 11. FIG. 11 is a flow chart showing an example of the operation of the determination unit 600. Here, in FIG. 11, the region from position p1 to position p2 where the conveyor belt 18c is driven to rotate is divided into n+1 regions, and in each divided region, the detection unit 500 detects whether the charging abnormality occurs in the conveyor belt 18c. Then, the determination unit 600 determines whether the charging abnormality is caused by an abnormality in the voltage supply unit 400 or an abnormality in the conveyor belt 18c based on the amount of rotation of the conveyor belt 18c, the detection result of the detection unit 500, and the determination condition signal JC.

[0096] 11, the description will be given using the conveying count Tc, the normal count Nc, and the abnormal count Ec. That is, they correspond to the rotation amount of the conveying belt 18c. Specifically, the conveying count Tc is set to "0" when the detection unit 500 detects the charge detection voltage CD at a predetermined position p1 of the conveying belt 18c and outputs the corresponding charge voltage determination signal CE, and the conveying count Tc is set to "n" when the detection unit 500 detects the charge detection voltage CD at a predetermined position p2 of the conveying belt 18c and outputs the corresponding charge voltage determination signal CE.

[0097] The normal count Nc indicates the number of times that a low-level charged voltage determination signal CE is input from the detection unit 500 during the period when the conveying count Tc goes from 0 to n, i.e., during the period when the conveying belt 18c rotates from position p1 to position p2. On the other hand, the abnormal count Ec indicates the number of times that a high-level charged voltage determination signal CE is input from the detection unit 500 during the period when the conveying count Tc goes from 0 to n, i.e., during the period when the conveying belt 18c rotates from position p1 to position p2.

[0098] 11, the discrimination unit 600 initializes the conveying count Tc, the normal count Nc, and the abnormal count Ec immediately before the conveying belt 18c reaches a predetermined position p1 (step S110). Specifically, the conveying count Tc, the normal count Nc, and the abnormal count Ec are all set to "0."

[0099] After that, the discrimination unit 600 judges whether the conveying count Tc is less than "n" (step S120). If the conveying count Tc is less than "n" (Y in step S120), the discrimination unit 600 judges whether the charged voltage of the conveying belt 18c is normal or not based on the logic level of the charged voltage judgment signal CE input from the detection unit 500 (step S130).

[0100] When the charge voltage determination signal CE input from the detection unit 500 is at a low level, the discrimination unit 600 determines that the charge voltage of the conveyor belt 18c is normal (Y in step S130) and adds "1" to the normal count Nc (step S140). After that, the discrimination unit 600 adds 1 to the conveyance count Tc (step S160) as the conveyor belt 18c rotates and the detection position of the conveyor belt 18c where the detection unit 500 detects the charge voltage moves, and again determines whether the conveyance count Tc is less than "n" (step S120).

[0101] On the other hand, when the charge voltage determination signal CE input from the detection unit 500 is at a high level, the discrimination unit 600 determines that the charge voltage of the conveyor belt 18c is abnormal (N in step S130) and adds "1" to the abnormality count Ec (step S150). After that, the discrimination unit 600 adds 1 to the conveyance count Tc (step S160) as the conveyor belt 18c rotates and the detection position of the conveyor belt 18c where the detection unit 500 detects the charge voltage moves, and again determines whether the conveyance count Tc is less than "n" (step S120).

[0102] The discrimination unit 600 performs the above-mentioned steps S120 to S160 on the conveyor belt 18c. In other words, the discrimination unit 600 repeats steps S120 to S11 described above until the transport count Tc becomes "n" or more. Repeat 60. In the following paragraphs, En is equivalent to Ec, and Nn is equivalent to Nc. is equivalent to: When the transport count Tc becomes equal to or greater than "n" (step S12 0), the discrimination unit 600 detects the abnormal count E n exceeds a certain threshold Eth It is determined whether or not 1 ) In other words, the transport count Tc goes from "0" to "n During the period until the charging voltage of the conveyor belt 18c becomes " The number of times that the high-level charged voltage determination signal CE, which indicates an abnormality, is detected is equal to or greater than the threshold value Et Determine whether or not h is exceeded.

[0103] And abnormal count E n If is less than or equal to the threshold value Eth (step S21 1 N), discrimination unit The unit 600 is a period during which the conveyance count Tc goes from "0" to "n", and the conveyance In the region from position p1 to position p2 where the belt 18c is rotated, the conveyor belt 18c It is determined that no charging abnormality has occurred, and it is indicated that no charging abnormality has occurred on the conveyor belt 18c. The discrimination result signal RD is output to the control unit 100 (step S250).

[0104] On the other hand, abnormal count E n exceeds the threshold Eth (step S21 1 Y), Judgement The other unit 600 is a period in which the transport count Tc goes from “0” to “n”, In at least a part of the region from position p1 to position p2 where the conveyor belt 18c is driven to rotate Then, the discrimination unit 600 determines that the conveyor belt 18c is abnormally charged. , normal count N n It is determined whether or not exceeds a predetermined threshold value Nth (step S22 0). In other words, during the period when the transport count Tc goes from "0" to "n", The unit 600 detects a low level charge voltage indicating that the charge voltage of the conveyor belt 18c is normal. It is determined whether the number of times the charged voltage determination signal CE is input exceeds a threshold value Nth.

[0105] Normal count N n If is less than or equal to the threshold value Nth (step S2 20 N), discrimination unit 6 00 is the period from when the conveying count Tc goes from "0" to "n", and the conveying belt 1 In the region from position p1 to position p2 where 8c is rotated, the conveyor belt 18c is abnormally charged. Since the period during which no vibration occurs is shorter than the predetermined threshold value Nth, the vibration generated on the conveyor belt 18c is It is determined that the cause of the charging abnormality is an abnormality in the voltage supply unit 400. The discrimination unit 600 determines whether the charge abnormality occurring on the conveyor belt 18c is caused by the voltage supply unit. A determination result signal RD indicating that the printer 400 is abnormal is generated and output to the control unit 100. Then, the CPU 11 inputs the command (step S240).

[0106] On the other hand, normal count N n If exceeds the threshold Nth (step S2 20 Y), The discrimination unit 600 is a period during which the transport count Tc goes from "0" to "n". In the region from position p1 to position p2 where the conveyor belt 18c is driven to rotate, Since the period during which no charging abnormality occurs in 8c exceeds a predetermined threshold value Nth, It is determined that the charge abnormality occurring in the conveyor belt 18c is caused by an abnormality in the conveyor belt 18c. The discrimination unit 600 then determines whether the cause of the charging abnormality occurring on the conveyor belt 18c is A discrimination result signal RD indicating that the conveyor belt 18c is abnormal is generated, and the control unit 10 The output is set to 0 (step S230).

[0107] As described above, when determining the cause of the charging abnormality occurring in the conveyor belt 18c, the threshold value Nth corresponding to the normal count Nc and the threshold value Eth corresponding to the abnormal count Ec used as the determination conditions by the determination unit 600 are specified by the determination condition signal JC output by the machine learning unit 800. That is, the threshold value Nth corresponding to the normal count Nc and the threshold value Eth corresponding to the abnormal count Ec are updated by the machine learning executed by the machine learning unit 800. This allows the determination unit 600 to determine the cause of the charging abnormality using the optimum threshold values ​​Nth and Eth according to the state of the conveyor belt 18c.

[0108] In addition, it is preferable that the region from position p1 to position p2, which is the predetermined range of the conveyor belt 18c, is the entire region of the conveyor belt 18c. That is, the positions p1 and p2 are the same points on the conveyor belt 18c, and the period during which the conveyor belt 18c moves from position p1 to position p2 corresponds to the period during which the conveyor belt 18c makes one rotation. This makes it possible to detect the presence or absence of a charging abnormality in the conveyor belt 18c in the entire region of the conveyor belt 18c, improving the accuracy of the discrimination result in the discrimination unit 600.

[0109] As described above, in the printing device 1 of this embodiment, the machine learning unit 800 generates a discrimination condition signal JC including thresholds Nth and Eth through machine learning based on the period required for the conveying belt 18c to move a predetermined amount and the charged voltage determination signal CE output by the detection unit 500 during that period, and the discrimination unit 600 determines whether or not a charging abnormality has occurred in the conveying belt 18c based on the period required for the conveying belt 18c to move a predetermined amount, the charged voltage determination signal CE output by the detection unit 500 during that period, and the thresholds Nth and Eth included in the discrimination condition signal JC, and if a charging abnormality has occurred in the conveying belt 18c, determines whether the charging abnormality is caused by an abnormality in the voltage supply unit 400 or an abnormality in the conveying belt 18c, thereby improving the discrimination accuracy of the discrimination unit 600.

[0110] 4.Conveyor belt coating Next, the coating material that covers the transport belt 18c will be described. In the printing device 1 of this embodiment, the transport belt 18c is coated with melamine resin that is resistant to damage such as scratches even if calcium carbonate or the like adheres to the transport belt 18c.

[0111] The coating agent for the transport belt 18c that transports the medium is subject to a number of conditions due to its use in the printing device 1.

[0112] The first condition is that the material must be highly resistant to organic solvents, salts, acids, alkalis, etc. A wide variety of printing materials are used in the printing process in the printer 1. Therefore, the conveyor belt 18c that conveys the medium on which the printing process is executed in the printer 1 is required to have high chemical resistance that is resistant to deterioration such as corrosion, regardless of the printing material selected.

[0113] In addition, as a second condition, high heat resistance is required. As described above, in the printing device 1, after the printing process is performed on the medium, the medium is heated by the heater 48 or the like in order to fix the printing material to the medium. The conveyor belt 18c is required to have high heat resistance so that it is not deformed or altered by this heating process. Furthermore, when the printing device 1 is used in a factory or the like, the printing device 1 will operate continuously for a long period of time. Therefore, the printing device 1 is required to be made of a material that does not emit smoke or catch fire even if an abnormality occurs in the printing device 1 during the long period of continuous operation. In other words, the material of the conveyor belt 18c used in the printing device 1 is required to have high heat resistance, such as a high heat resistance temperature that can withstand overheating by the heater 48 or the like, and flame retardant performance that is unlikely to cause smoke or catch fire.

[0114] Taking these factors into consideration, in the previous printing device 1, a material that meets the first condition of high resistance to organic solvents, salts, acids, alkalis, etc., and the second condition of high heat resistance, was used as a coating agent for the conveyor belt 18c.

[0115] However, in a printing device 1 that prints on a medium containing calcium carbonate and that increases the adhesiveness of the medium to the conveyor belt 18c by charging the conveyor belt 18c along which the medium is conveyed, a problem occurs in that, even though a voltage supply unit 400 for storing electric charge in the conveyor belt 18c is operating normally, an abnormality in the charged voltage occurs in the conveyor belt 18c, causing the printing device 1 to stop printing. The inventor, who faced this problem, discovered that the reason the printing device 1 stops printing is that calcium carbonate contained in the medium accumulates inside the printing device 1 due to long-term use of the printing device 1, and the accumulated calcium carbonate reacts with moisture in the air and moisture contained in the printing material and coagulates, damaging the conveyor belt 18c, resulting in an abnormality in the charged voltage of the conveyor belt 18c. In order to solve the problem of abnormalities in the charged voltage occurring in the conveying belt 18c even though the voltage supply unit 400 for storing electric charge in the conveying belt 18c is operating normally, it has been found that it is effective to add the compressive strength of the coating material as a new third condition when selecting the coating material for the conveying belt 18c.

[0116] Fig. 12 is a diagram showing an example of a coating agent that can be used for the conveyor belt 18c. As shown in Fig. 12, in the printing device 1, examples of the material of the conveyor belt 18c that satisfies the two indices of chemical resistance, which is the first condition, and heat resistance, which is the second condition, include polyethylene (PE), polypropylene (PP), polyvinylidene difluoride (PVDF), fluorine-based resin, and melamine resin. Of these, polyethylene has been widely used as a coating agent for the conveyor belt 18c in the conventional printing device 1 from the viewpoints of cost, delivery, versatility, and the like.

[0117] In contrast, in the printing device 1 that performs printing processing on a medium containing calcium carbonate, by taking into account the newly discovered third condition, that is, the index of compressive strength, it is found that melamine resin is more suitable for use as the coating material for the conveyor belt 18c, as shown in FIG. 12. This reduces the risk of damage to the conveyor belt 18c caused by calcium carbonate adhering to the conveyor belt 18c, even when printing processing is performed on a medium containing calcium carbonate for a long period of time, and reduces the risk of charging abnormalities caused by abnormalities in the conveyor belt 18c, which is charged with an electric charge. In other words, the risk of the printing device 1 unintentionally stopping the printing processing is reduced, and stable operation of the printing device 1 can be achieved.

[0118] 5. Effects As described above, the printing device 1 in this embodiment has a discrimination unit 600 that discriminates whether the cause of the charging abnormality occurring in the conveyor belt 18c that conveys a medium containing calcium carbonate is an abnormality in the voltage supply unit 400 or an abnormality in the conveyor belt 18c, and the discrimination condition for discriminating whether the cause of the charging abnormality occurring in the conveyor belt 18c is an abnormality in the voltage supply unit 400 or an abnormality in the conveyor belt 18c in the discrimination unit 600 is obtained by machine learning based on a learning model in which the rotation amount of the conveyor belt 18c and the detection result of the detection unit 500 are associated with each other by the machine learning unit 800. As a result, even if the abnormality occurring in the conveyor belt 18c changes due to the rotational drive of the conveyor belt, the discrimination unit 600 can accurately discriminate whether the cause of the charging abnormality occurring in the conveyor belt 18c is an abnormality in the voltage supply unit 400 or an abnormality in the conveyor belt 18c. Then, by controlling the printing device 1 according to the discrimination result of the discrimination unit 600, the stability of the operation of the printing device 1 is improved.

[0119] Therefore, the printing device 1 in this embodiment can improve the operational stability of the printing device 1 even in printing devices 1 in which there is a high risk of solidified calcium carbonate adhering to the conveyor belt 18c, such as a printing device 1 that performs a printing process on lime plaster paper that contains a large amount of calcium carbonate, a printing device 1 that has a heater 48 that fixes the printing material to the medium and therefore may promote a chemical reaction between calcium carbonate and moisture, and a printing device 1 such as an inkjet printer that forms an image on a medium by ejecting ink that contains moisture.

[0120] 6. Variations In the printing device 1 described above, the medium containing calcium carbonate has been described as plaster paper coated with plaster, but this is not limited to this, and the same effects can be achieved even if the medium on which the printing process is performed in the printing device 1 is fine paper, medium quality paper, coated base paper, etc. that contain calcium carbonate.

[0121] In addition, in this embodiment, the detection unit 500 detects whether or not there is an abnormality in the charging voltage applied to the conveying belt 18c depending on whether the charging detection voltage CD input from the conveying unit 300 is above or below the corrected threshold information HCth corresponding to the threshold information Cth, but the detection unit 500 may also use two thresholds to detect whether or not there is an abnormality in the charging voltage applied to the conveying belt 18c depending on whether the charging detection voltage CD input from the conveying unit 300 is between the two thresholds.

[0122] Although the embodiments and modifications have been described above, the present invention is not limited to these embodiments, and can be embodied in various forms without departing from the spirit of the present invention. For example, the above embodiments can be appropriately combined.

[0123] The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations with the same functions, methods and results, or configurations with the same purpose and effect). The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that achieve the same effects as the configurations described in the embodiments or that can achieve the same purpose. The present invention also includes configurations in which publicly known technology is added to the configurations described in the embodiments.

[0124] The following can be derived from the above-described embodiment.

[0125] One aspect of the printing device is A printing means for printing on a medium containing calcium carbonate; a conveying unit that rotates a conveying belt that constitutes at least a part of a conveying path along which the medium is conveyed; a voltage supplying means for supplying a charging voltage to a charging roller for charging the conveyor belt; a detection means for detecting whether or not a charging abnormality occurs on the conveyor belt; a discrimination means for discriminating whether the cause of the charging abnormality is an abnormality in the voltage supply means or an abnormality in the conveyor belt; a machine learning means for learning by machine learning a discrimination condition in the discrimination means based on a learning model in which the rotation amount of the conveyor belt and the detection result of the detection means are associated with each other; Equipped with.

[0126] According to this printing device, the discrimination means discriminates whether the cause of the charging abnormality occurring in the conveyor belt that conveys a medium containing calcium carbonate is an abnormality in the voltage supply means or an abnormality in the conveyor belt based on discrimination conditions obtained by machine learning based on a learning model that associates the amount of rotation of the conveyor belt with the detection result of the detection means in the machine learning means. This enables the discrimination means to discriminate the cause of the charging abnormality occurring in the conveyor belt based on discrimination conditions according to the state of the conveyor belt, thereby improving the discrimination accuracy by the discrimination means. Then, by controlling the printing device according to the discrimination result of the discrimination means, the stability of the operation of the printing device is improved.

[0127] In one aspect of the printing device, The determining unit may determine a cause of the charging abnormality based on the determining condition, the amount of rotation of the conveyor belt, and a detection result of the detecting unit.

[0128] According to this printing device, the discrimination means discriminates whether the cause of the charging abnormality occurring in the conveyor belt is an abnormality in the voltage supply means or an abnormality in the conveyor belt based on the discrimination conditions obtained by the machine learning means through machine learning, the amount of rotation of the conveyor belt, and the detection result of the presence or absence of a charging abnormality by the detection means, thereby further improving the discrimination accuracy by the discrimination means, thereby further improving the stability of the operation of the printing device controlled according to the discrimination result by the discrimination means.

[0129] In one aspect of the printing device, The detection means includes: a recording section in which threshold information is recorded; a threshold correction unit that corrects the threshold information; a comparison unit that detects whether the charging abnormality occurs by comparing the corrected threshold information with the charge amount of the conveyor belt; may have the following structure:

[0130] According to this printing device, the presence or absence of a charging abnormality in the detection means can be detected with high accuracy.

[0131] In one aspect of the printing device, When the determining unit determines that the charge abnormality is caused by an abnormality in the conveyor belt, the threshold correction unit may correct the threshold information so as to ease detection of the charge abnormality.

[0132] According to this printing device, when the determination means determines that the cause of the charge abnormality of the conveyor belt is an abnormality of the conveyor belt that is unlikely to have any repercussions, the risk of the charge abnormality of the conveyor belt continuing to occur is reduced. In other words, the inconvenience caused by the charge abnormality of the conveyor belt continuing to occur is reduced, and the convenience of the printing device for the user is improved.

[0133] In one aspect of the printing device, The voltage value of the charging voltage may be adjusted based on the result of the determination by the determining means.

[0134] According to this printing device, the voltage value of the charging voltage is adjusted in accordance with the result of the determination by the determination means, thereby making it possible to reduce the risk of the charging abnormality occurring continuously on the transport belt.

[0135] In one aspect of the printing device, The charger may further include a notification unit that issues a warning when the determination unit determines that the charging abnormality is caused by an abnormality in the conveyor belt.

[0136] According to this printing device, when it is determined that the cause of the charging abnormality is an abnormality in the conveyor belt, the notification unit issues a warning, urging the user to replace the conveyor belt. This reduces the risk of the damaged conveyor belt being used continuously, and as a result, further reduces the risk of the stability of the printing device's operation decreasing.

[0137] In one aspect of the printing device, The learning result obtained by the machine learning means may be initialized when the conveyor belt is replaced.

[0138] According to this printing device, it can be assumed that the damage to the conveyor belt has been removed by replacing the conveyor belt. By initializing the learning result corresponding to the removal of such damage, it is possible to improve the accuracy of detecting the charging abnormality in the replaced conveyor belt and the accuracy of identifying the cause of the above.

[0139] In one aspect of the printing device, The medium may be plaster paper coated with plaster.

[0140] According to this printing device, the discrimination means can accurately determine the cause of the charging abnormality that has occurred on the conveying belt, thereby reducing the risk of the operational stability of the printing device decreasing even when the medium is lime plaster paper that contains a large amount of calcium carbonate.

[0141] In one aspect of the printing device, The apparatus may further include a heating means for heating the medium.

[0142] With this printing device, the discrimination means can accurately determine the cause of the charging abnormality that has occurred on the conveying belt, thereby reducing the risk of the operational stability of the printing device decreasing even if the printing device is equipped with a heating means for heating the medium.

[0143] In one aspect of the printing device, The printing unit may perform printing by discharging or applying a water-soluble printing material onto the medium.

[0144] According to this printing device, the discrimination means can accurately determine the cause of the charging abnormality that has occurred on the conveying belt, thereby reducing the risk of the operational stability of the printing device decreasing, even when the printing device prints by ejecting or applying water-soluble printing material onto the medium. [Explanation of symbols]

[0145] 1...printing device, 2A...device main body, 2B...additional unit, 2C...additional unit, 3...scanner unit, 4...output tray, 5...operation panel, 6...opening cover, 6a...oscillating shaft, 7...output tray, 7a...rotating shaft, 8...print head, 10A, 10B, 10C...media cassette, 11...hopper, 11a...shaft, 12...feed roller, 13...separation roller pair, 14...transport roller pair, 15...feed roller, 16...separation roller, 17...registration roller pair, 17a...driving roller, 17b...driven roller, 18...belt unit, 18a...driving pulley, 18b...driven pulley, 18c...conveyor belt, 18d...suction surface, 19a, 19b...driven roller, 20, 21, 22, 23, 24...conveyor roller pair, 25...discharge roller pair, 26, 27, 28, 29...conveyor roller pair, 29a...driving roller, 29b...driven roller, 31...flap, 31a...oscillation fulcrum, 32...flap, 32a...oscillation fulcrum, 3 3...flap, 35...feed unit, 37...motor, 41...manual feed tray, 41a...oscillating shaft, 43...discharge brush, 44...charging roller, 45, 46...support plate, 47...cleaning blade, 48...heater, 49...power supply device, 100...control unit, 200...printing unit, 210...drive signal output unit, 300...transport unit, 400...voltage supply unit, 500...detection unit, 510...recording circuit, 520...threshold correction circuit, 530...comparison circuit, 600...discrimination unit, 700...interface unit, 800...machine learning unit, 810...learning model storage unit, 820...learning model update unit, F...roller, G...roller, PI...position information signal, R1...recording transport path, R2...switchback transport path, R3...reversal transport path, R4...face-down transport path, R5...face-up transport path, S1, S2, S3...feed trajectory, Sc1, Sc2...scratch, T1, T2...ejection trajectory

Claims

1. A printing means for printing on a medium containing calcium carbonate; A conveyor belt that constitutes at least a part of a conveying path along which the medium is conveyed is rotated. A conveying means; a voltage supplying means for supplying a charging voltage to a charging roller for charging the conveyor belt; a detection means for detecting whether or not a charging abnormality occurs on the conveyor belt; Whether the cause of the charging abnormality is an abnormality in the voltage supply means or an abnormality in the conveyor belt, A determination means for determining The amount of rotation of the conveyor belt, the detection result of the detection means, and the presence or absence of an abnormality in the voltage supply means and a learning model in which the judgment result of the judgment unit including the presence or absence of an abnormality in the conveyor belt is associated with the R A machine learning means for machine learning a discrimination condition in the discrimination means based on the above. Equipped with A printing device comprising:

2. The determining means determines the determination condition, the amount of rotation of the conveyor belt, and the detection result of the detecting means. and determining a cause of the charging abnormality based on the result.

2. The printing device according to claim 1.

3. The detection means includes: a recording section in which threshold information is recorded; a threshold correction unit that corrects the threshold information; The corrected threshold information is compared with the amount of charge on the conveyor belt. A comparison unit that detects whether or not a charging abnormality has occurred; having 3. The printing apparatus according to claim 1, wherein the first and second printing units are arranged in a first direction.

4. When the determining means determines that the charge abnormality is caused by an abnormality in the conveyor belt, In this case, the threshold correction unit corrects the threshold information so as to mitigate the detection of the charging abnormality.

4. The printing device according to claim 3.

5. The voltage value of the charging voltage is adjusted based on the determination result of the determination means.

5. The printing apparatus according to claim 1, wherein the first and second printing units are arranged in a first direction.

6. When the determining means determines that the charge abnormality is caused by an abnormality in the conveyor belt, a notification unit that notifies warning information when 6. The printing apparatus according to claim 1, wherein the first and second printing units are arranged in a first direction.

7. The learning result obtained by the machine learning means is initialized when the conveyor belt is replaced. To be done, 7. The printing apparatus according to claim 1, wherein the first and second printing units are arranged in a first direction.

8. The medium is plaster paper coated with plaster; 8. The printing device according to claim 1, wherein the first and second printing units are arranged in a first direction.

9. A heating means for heating the medium is provided.

9. The printing device according to claim 1, wherein the first and second printing units are arranged in a first direction.

10. The printing means performs printing by discharging or applying a water-soluble printing material onto the medium.

10. The printing device according to claim 1, wherein the first and second printing units are arranged in a first direction.

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