Printer

Abstract

To provide a technique which can easily specify a deformed driven roller when strong tension is applied to a printing medium, and can suppress deformation of a partial important driven roller.SOLUTION: A conveyance mechanism 10 of a printer 1 has a plurality of driven rollers 12. At least the one driven roller 12 among the plurality of driven rollers 12 is a sacrificial roller 70 which is easily deformed compared to the other driven rollers 12. When strong tension is applied to a printing medium 9, the sacrificial roller 70 is preferentially deformed compared to the other driven rollers 12. Thereby, specification of the deformed driven roller 12 is facilitated. In addition, deformation of the driven rollers 12 other than the sacrificial roller 70 can be suppressed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an inkjet printing apparatus. [Background technology]

[0002] A printing device that uses an inkjet printing method to print on the surface of a long, strip-shaped print medium while transporting the print medium in the longitudinal direction has been known. The printing device has multiple rollers that transport the print medium. The multiple rollers include a drive roller that is rotated by the power of a motor and a driven roller that rotates as the print medium moves.

[0003] A conventional printing device is described in, for example, Patent Document 1. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-37537 Summary of the Invention [Problem to be solved by the invention]

[0005] In this type of printing device, if the print medium unwinding or winding section operates abnormally, excessive tension is applied to the print medium. This can cause some of the driven rollers to deform. In such cases, it takes time to identify the deformed driven roller from among the many driven rollers. This requires the printing device to be stopped for an extended period of time.

[0006] Furthermore, there is a demand for protecting some important driven rollers, such as driven rollers used in encoders, from deformation even when excessive tension is applied to the print medium.

[0007] Therefore, the present invention aims to provide a technology that can easily identify deformed driven rollers when strong tension is applied to a printing medium, and can prevent some important driven rollers from deforming. [Means for solving the problem]

[0008] In order to solve the above problem, the first invention of the present application comprises a transport mechanism that transports a long strip of printing medium in a longitudinal direction, a head that ejects ink onto the printing medium transported by the transport mechanism, and a control unit that controls the transport mechanism and the head, wherein the transport mechanism has a drive roller that actively rotates by power output from a motor, and a plurality of driven rollers that rotate passively as the printing medium moves, and at least one of the plurality of driven rollers is a sacrificial roller that is more susceptible to deformation than the other driven rollers.

[0009] The second invention of the present application is a printing device of the first invention, further comprising a housing having an inlet and outlet for the printing medium and accommodating the transport mechanism and the head therein, and the sacrificial roller is located near the inlet or outlet within the housing.

[0010] A third invention of the present application is the printing device of the second invention, wherein the sacrificial roller is the second driven roller, counting from the carry-in entrance or the carry-out exit, among the plurality of driven rollers.

[0011] A fourth invention of the present application is a printing device according to any one of the first to third inventions, further comprising a tension sensor that detects the tension of the printing medium, and the control unit extracts a fluctuation component of the tension corresponding to the sacrificial roller from the time series data of tension output from the tension sensor, and detects deformation of the sacrificial roller based on the fluctuation component.

[0012] The fifth invention of the present application is a printing device of the fourth invention, wherein the diameter of the outer surface of the sacrificial roller that contacts the printing medium is not an integer multiple of the diameter of the outer surface of the other driven roller that contacts the printing medium, nor is it an integer multiple of that diameter.

[0013] A sixth aspect of the present invention is the printing device of any one of the first to fifth aspects, wherein the sacrificial roller has a shaft extending along a central axis, and the shaft has a constricted portion.

[0014] A seventh invention of the present application is a printing device according to any one of the first to fifth inventions, wherein the sacrificial roller has a shaft extending along a central axis, and the shaft has a hollow inside. [Effects of the Invention]

[0015] According to the first to seventh aspects of the present invention, when a strong tension is applied to the print medium, the sacrificial roller can be deformed preferentially over the other driven rollers. This makes it easier to identify the deformed driven roller. Also, it is possible to prevent the deformation of driven rollers other than the sacrificial roller.

[0016] In particular, according to the second aspect of the present invention, the user can easily check the condition of the sacrificial roller, and can easily replace a deformed sacrificial roller with a new one.

[0017] In particular, according to the third aspect of the present invention, the sacrificial roller is disposed near the inlet or outlet, and the wrap angle of the printing medium around the sacrificial roller can be kept substantially constant.

[0018] In particular, according to the fourth aspect of the present invention, the control unit can detect that the sacrificial roller has been deformed.

[0019] In particular, according to the fifth aspect of the present invention, the period of fluctuation in tension caused by the sacrificial roller can be made different from the period of fluctuation in tension caused by other driven rollers, and therefore the fluctuation component of tension corresponding to the sacrificial roller can be extracted with high accuracy from the tension time-series data. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 illustrates a configuration of a printing device. [Figure 2] FIG. 1 is a view of one head viewed from below. [Figure 3] FIG. 2 is a control block diagram of the printing apparatus. [Figure 4] FIG. 2 is a perspective view of the vicinity of an end of a sacrificial roller. [Figure 5] 10 is a flowchart showing a procedure for detecting deformation of a sacrificial roller. [Figure 6] FIG. 2 is a perspective view of the vicinity of an end of a sacrificial roller. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0022] <1. Printer configuration> FIG. 1 is a diagram showing the configuration of a printing device 1 according to one embodiment of the present invention. This printing device 1 is a device that performs inkjet printing on a long, strip-shaped printing medium 9. The printing device 1 prints an image on the surface of the printing medium 9 by ejecting ink from multiple heads 21 toward the printing medium 9 while transporting the printing medium 9 in the longitudinal direction. The printing medium 9 may be printing paper or a resin film. As shown in FIG. 1, the printing device 1 includes a housing 60, a transport mechanism 10, an encoder 13, a tension sensor 15, a printing unit 20, a drying unit 30, an inspection unit 40, a control unit 50, an unwinding unit 80, and a winding unit 90.

[0023] The housing 60 is a housing that houses the conveyance mechanism 10, encoder 13, tension sensor 15, printing unit 20, drying unit 30, and inspection unit 40. The housing 60 has an inlet 61 through which the print medium 9 is carried in and an outlet 62 through which the print medium 9 is carried out. As shown in FIG. 1 , the printing device 1 of this embodiment has a printing area A1, a drying area A2, and an inspection area A3 inside the housing 60. The printing area A1, drying area A2, and inspection area A3 are aligned in the direction from the inlet 61 to the outlet 62.

[0024] The unwinding unit 80 is disposed outside the entrance 61 of the housing 70. The unwinding unit 80 includes an unwinding roll 81 on which the printing medium 9 is wound into a roll before printing by the printing unit 20, and a motor (not shown) that rotates the unwinding roll 81 around a rotation shaft 82 to unwind the printing medium 9 from the unwinding roll 81 in the direction of the arrow.

[0025] The winding unit 90 is disposed outside the discharge port 62 of the housing 70. The winding unit 90 includes a winding roll 91 that winds up and collects the printing medium 9 after printing by the printing unit 20, and a motor (not shown) that rotates the winding roll 91 around a rotation shaft 92 to move the printing medium 9 discharged from the housing 60 in the direction of the arrow.

[0026] The transport mechanism 10 is a mechanism that transports the print medium 9 within the housing 60. The transport mechanism 10 of this embodiment has a plurality of drive rollers 11 and a plurality of driven rollers 12. The print medium 9 is stretched across the plurality of drive rollers 11 and the plurality of driven rollers 12 under tension.

[0027] The printing medium 9 is unwound from an unwinding roll 81 located outside the carry-in entrance 61 and transported along a transport path formed by multiple drive rollers 11 and multiple driven rollers 12. The multiple drive rollers 11 and multiple driven rollers 12 each rotate around an axis parallel to the width direction of the printing medium 9 (a direction perpendicular and horizontal to the transport direction), thereby guiding the printing medium 9 downstream of the transport path. After transport, the printing medium 9 is collected on a take-up roll 91 located outside the carry-in exit 62.

[0028] Drive rollers 11 are arranged at multiple locations along the transport path. Each drive roller 11 has a cylindrical outer circumferential surface. The print medium 9 comes into contact with this outer circumferential surface of the drive roller 11. The drive roller 11 is connected to a motor 111. The drive roller 11 actively rotates due to the power output from the motor 111. This moves the print medium 9 downstream along the transport path.

[0029] The driven rollers 12 are arranged at multiple locations on the transport path. The number of driven rollers 12 is greater than the number of drive rollers 11. The driven rollers 12 have a cylindrical outer surface. The print medium 9 comes into contact with the outer surface of the driven rollers 12. When the print medium 9 is transported by the drive rollers 11, the driven rollers 12 also rotate in accordance with the movement of the print medium 9.

[0030] The encoder 13 is a sensor that detects the transport speed of the print medium 9. The encoder 13 is connected to one of the multiple driven rollers 12. The encoder 13 is electrically connected to the control unit 50. The encoder 13 detects the rotation angle of the driven roller 12. Specifically, the encoder 13 outputs a pulse signal each time the driven roller 12 rotates a predetermined angle. The pulse signal is sent from the encoder 13 to the control unit 50.

[0031] The tension sensor 15 is a sensor that detects the tension applied to the print medium 9. The tension sensor 15 is provided on the transport path of the print medium 9. The tension sensor 15 has a sensor roller 151 that contacts the print medium 9, and a load cell 152 connected to the sensor roller 151. The load cell 152 measures the load applied to the sensor roller 151 from the print medium 9. In this way, the tension sensor 15 detects the tension of the print medium 9. The tension sensor 15 then sends a detection signal indicating the tension of the print medium 9 to the control unit 50.

[0032] The printing unit 20 is a unit that ejects ink droplets (hereinafter referred to as "ink droplets") onto the print medium 9 transported by the transport mechanism 10. The printing unit 20 is provided in the printing area A1 inside the housing 60. In this embodiment, the printing unit 20 has four heads 21. The four heads 21 are arranged at intervals along the transport direction of the print medium 9. The print medium 9 is transported below the four heads 21 with the printing surface facing upward.

[0033] FIG. 2 is a view of one head 21 as viewed from below. In FIG. 2, the print medium 9 is indicated by an imaginary line (two-dot chain line). As shown enlarged in FIG. 2, the underside of the head 21 is provided with a plurality of nozzles 211 capable of ejecting ink droplets. In this embodiment, the plurality of nozzles 211 are arranged two-dimensionally in the transport direction and width direction on the underside of the head 21. The nozzles 211 are arranged with their positions shifted in the width direction. However, the plurality of nozzles 211 may also be arranged in a line along the width direction.

[0034] The four heads 21 eject ink droplets of different colors from multiple nozzles 211 toward the top surface of the print medium 9. For example, black, cyan, magenta, and yellow inks are ejected from the four heads 21, respectively. A multicolor image is formed on the surface of the print medium 9 by superimposing the monochromatic images formed by these ink colors.

[0035] The drying unit 30 is a unit that dries the ink on the print medium 9. The drying unit 30 is provided in the drying area A2 inside the housing 60. The drying unit 30 has multiple heaters 31. The heaters 31 irradiate the print medium 9 with infrared rays, which causes the solvent to evaporate from the ink on the print medium 9. As a result, the ink dries and becomes fixed on the print medium 9. However, the heaters 31 may also heat the ink by blowing heated air onto the print medium 9, for example.

[0036] The inspection unit 40 is a unit that inspects the image printed on the print medium 9. The inspection unit 40 is provided in the inspection area A3 inside the housing 60. The inspection unit 40 has multiple cameras 41. The cameras 41 photograph the surface of the print medium 9 and transmit the obtained inspection images to the control unit 50. The control unit 50 inspects the quality of the image printed on the print medium 9 based on the inspection images received from the cameras 41.

[0037] The control unit 50 is an information processing device for controlling each unit within the printing device 1. Fig. 3 is a control block diagram of the printing device 1. As shown in Fig. 3, the control unit 50 is configured by a computer having a processor 501 such as a CPU, a memory 502 such as a RAM, and a storage unit 503 such as a hard disk drive. A computer program P for executing the printing process is stored in the storage unit 503.

[0038] 3, the control unit 50 is communicably connected, via wire or wireless, to the above-mentioned multiple motors 111, encoder 13, tension sensor 15, four heads 21, multiple heaters 31, and multiple cameras 41. The control unit 50 reads a computer program P from a storage unit 503 into a memory 502, and controls the above-mentioned components by operating a processor 501 in accordance with the computer program P. This allows the transport of the print medium 9 and the printing process to proceed.

[0039] <2. About the Sacrificial Roller> The above-described plurality of driven rollers 12 includes a sacrificial roller 70. In this embodiment, two of the plurality of driven rollers 12 are sacrificial rollers 70. The sacrificial rollers 70 are rollers that are more easily deformed than the other driven rollers 12. One of the two sacrificial rollers 70 is located near the inlet 61 of the housing 60. The other of the two sacrificial rollers 70 is located near the outlet 62 of the housing 60.

[0040] FIG. 4 is a perspective view of the vicinity of one end of the sacrificial roller 70. As shown in FIG. 4, the sacrificial roller 70 has a cylindrical roller body 71 and a columnar shaft 72 that supports the roller body 71. The print medium 9 contacts the outer peripheral surface of the roller body 71. The shaft 72 protrudes from both ends of the roller body 71 along the central axis X of the sacrificial roller 70. The outer diameter of the shaft 72 is smaller than the outer diameter of the roller body 71. The end of the shaft 72 is supported by the inner wall of the housing 60.

[0041] As shown in FIG. 4, the shaft 72 has a constricted portion 73. The constricted portion 73 is an annular recess formed on the outer circumferential surface of the shaft 72. The constricted portion 73 is not a recess provided for fastening to another component. Therefore, the constricted portion 73 is used in an open state without engaging with another component. The outer diameter of the constricted portion 73 is smaller than the outer diameter of the rest of the shaft 72. Therefore, when an external force acts on the shaft 72, the constricted portion 73 is more easily deformed than the rest of the shaft 72 due to stress concentration. The shafts of the driven rollers 12 other than the sacrificial roller 70 do not have such a constricted portion 73.

[0042] For example, if an operational abnormality occurs in the unwinding section or the winding section, the tension on the print medium 9 becomes greater than normal. When the tension on the print medium 9 increases, the print medium 9 applies a stronger pressure than normal to each of the multiple driven rollers 12. In such a case, the constricted portion 73 of the sacrificial roller 70 deforms preferentially over the other driven rollers 12.

[0043] In the past, without such a sacrificial roller 70, when excessive tension was applied to the print medium 9 and some of the driven rollers 12 were deformed, it was difficult to identify the deformed driven roller 12 from among the many driven rollers 12. As a result, it was necessary to stop the printing device 1 for a long time to identify the deformed driven roller 12. However, with this printing device 1, of the multiple driven rollers 12, the sacrificial roller 70 deforms first. As a result, it is easy to identify the deformed driven roller 12.

[0044] Furthermore, when excessive tension is applied to the printing medium 9, by deforming the sacrificial roller 70 first, deformation of the driven rollers 12 other than the sacrificial roller 70 can be suppressed. This makes it possible to protect the important driven rollers 12 for which deformation is particularly desired to be avoided. For example, when the driven roller 12 connected to the encoder 13 deforms, the detection accuracy of the encoder 13 decreases. However, in the structure of this embodiment, by providing the sacrificial roller 70, deformation of the driven roller 12 connected to the encoder 13 can be suppressed. Therefore, even when excessive tension is applied to the printing medium 9, a decrease in the detection accuracy of the encoder 13 can be suppressed.

[0045] Here, the angle of the outer circumferential surface of the driven roller 12, centered on the rotation axis of the portion that contacts the print medium 9, is referred to as the "wrap angle." The wrap angle of the sacrificial roller 70 is desirably larger than the wrap angles of the other driven rollers 12. Specifically, the wrap angle of the sacrificial roller 70 is desirably larger than 90°. This allows pressure to be applied efficiently from the print medium 9 to the sacrificial roller 70. Therefore, when excessive tension is applied to the print medium 9, the sacrificial roller 70 can be more easily deformed.

[0046] In this embodiment, one of the two sacrificial rollers 70 is located near the inlet 61 of the housing 60. Specifically, one of the two sacrificial rollers 70 is located between the inlet 61 and the head 21 of the printing unit 20, and is positioned closer to the inlet 61 than the head 21. The other of the two sacrificial rollers 70 is located near the outlet 62 of the housing 60. Specifically, the other of the two sacrificial rollers 70 is located between the camera 41 of the inspection unit 40 and the outlet 62, and is positioned closer to the outlet 62 than the camera 41.

[0047] In this way, by arranging the sacrificial roller 70 near the carry-in entrance 61 or the carry-out exit 62, the user can easily visually check whether the sacrificial roller 70 has been deformed. Furthermore, if the sacrificial roller 70 is deformed, the user can easily replace the sacrificial roller 70 with a new sacrificial roller 70.

[0048] However, if the transport layout inside the unwinding section 80 changes, the transport angle of the printing medium 9 transported into the inlet 61 also changes. For example, in the example of the unwinding section 80 shown in FIG. 1 , the printing medium is transported from the underside of the horizontally supported unwinding roll 81. However, depending on the unwinding section 80, the printing medium 9 may be transported from the upper surface of the horizontally supported unwinding roll 81. Therefore, the wrap angle of the driven roller 12 closest to the inlet 61 changes depending on the possible configuration of the unwinding section 80. Furthermore, when the diameter of the unwinding roll 81 changes as the printing medium 9 is unwound, the wrap angle of the driven roller 12 closest to the inlet 61 also changes. Therefore, in this embodiment, the sacrificial roller 70 is not the driven roller 12 closest to the inlet 61, but the driven roller 12 adjacent to that driven roller 12 on the downstream side. In other words, the second driven roller 12 counting from the inlet 61 is the sacrificial roller 70. This allows the winding angle of the printing medium 9 around the sacrificial roller 70 to be kept constant even if the layout inside the unwinding section 80 changes or the diameter of the unwinding roll 81 changes as the printing medium 9 is consumed.

[0049] Similarly, when the transport layout inside the winding unit 90 changes, the transport angle of the printing medium 9 transported from the discharge outlet 62 also changes. Therefore, the wrap angle of the driven roller 12 closest to the discharge outlet 62 changes depending on the possible configuration of the winding unit 90. Furthermore, when the diameter of the winding roll 91 changes as the printing medium 9 is wound, the wrap angle of the driven roller 12 closest to the discharge outlet 62 also changes. Therefore, in this embodiment, the driven roller 12 adjacent to the driven roller 12 closest to the discharge outlet 62 is used as the sacrificial roller 70, rather than the driven roller 12 closest to the discharge outlet 62. In other words, the second driven roller 12 counting from the discharge outlet 62 is used as the sacrificial roller 70. This makes it possible to maintain a constant wrap angle of the printing medium 9 around the sacrificial roller 70.

[0050] <3. Method for detecting deformation of the sacrificial roller> Next, a description will be given of a method for detecting deformation of the sacrificial roller 70 in the printing apparatus 1. Fig. 5 is a flowchart showing the procedure for detecting deformation of the sacrificial roller 70.

[0051] In this printing device 1, the tension sensor 15 detects the tension applied to the print medium 9 in the transport direction while the print medium 9 is being transported. The tension sensor 15 sends a detection signal indicating the tension of the print medium 9 to the control unit 50. The tension sensor 15 continuously performs this detection operation at very short time intervals. As a result, the control unit 50 obtains time-series data indicating the change in tension over time (step S1).

[0052] The control unit 50 performs frequency analysis using a Fourier transform on the obtained time-series data of tension. As a result, the tension fluctuation component corresponding to the sacrificial roller 70 is extracted from the time-series data (step S2). The tension fluctuation component caused by the sacrificial roller 70 has a period corresponding to the circumferential length of the roller body 71 of the sacrificial roller 70.

[0053] In step S2, to easily distinguish between the tension fluctuation component corresponding to the sacrificial roller 70 and the tension fluctuation component corresponding to the other driven rollers 12, the diameter of the outer peripheral surface of the sacrificial roller 70 that contacts the print medium 9 may be different from the diameter of the outer peripheral surface of the other driven rollers 12 that contacts the print medium 9. Specifically, the diameter of the outer peripheral surface of the sacrificial roller 70 that contacts the print medium 9 should be set to a size that is not an integer multiple of the diameter of the outer peripheral surface of the other driven rollers 12 that contacts the print medium 9, nor an integer multiple thereof. In this way, the tension fluctuation period caused by the sacrificial roller 70 and the tension fluctuation period caused by the other driven rollers 12 are less likely to overlap. Therefore, the tension fluctuation component corresponding to the sacrificial roller 70 can be accurately extracted from the tension time-series data.

[0054] Thereafter, the control unit 50 determines whether the fluctuation range of the tension corresponding to the sacrificial roller 70 has become larger than a preset threshold value (step S3). If the fluctuation range of the tension corresponding to the sacrificial roller 70 is equal to or smaller than the threshold value, the control unit 50 determines that the sacrificial roller 70 has not deformed (step S3: No). In this case, the process returns to step S1, and the processes of steps S1 to S3 are repeated.

[0055] On the other hand, if the fluctuation range of the tension corresponding to the sacrificial roller 70 becomes larger than the threshold value, the control unit 50 determines that the sacrificial roller 70 has been deformed (step S3: Yes). In this case, the control unit 50 outputs a warning (step S4). The warning may be output by displaying a warning message on a display or by sounding a warning sound. The warning may also be output by transmitting warning information to another information terminal connected via a network.

[0056] When the warning is output, the user stops the printing device 1 and checks the condition of the constricted portion 73 of the sacrificial roller 70. If the constricted portion 73 of the sacrificial roller 70 is deformed, the user replaces the sacrificial roller 70 with a new sacrificial roller 70 (step S5). At this time, the user can check the sacrificial roller 70 first, rather than checking the many driven rollers 12 one by one. This reduces the time required for the checking work. Therefore, the operation of the printing device 1 can be resumed promptly.

[0057] <4. Modifications> Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

[0058] FIG. 6 is a perspective view of the vicinity of an end of a sacrificial roller 70 having a structure different from that of the above-described embodiment. In the above-described embodiment, the sacrificial roller 70 has a constricted portion 73 on the shaft 72. However, the sacrificial roller 70 may have a structure different from that of the constricted portion 73. In the example of FIG. 6, the sacrificial roller 70 has a cylindrical shaft 72. That is, while the shafts 72 of the driven rollers 12 other than the sacrificial roller 70 are solid and cylindrical, the sacrificial roller 70 of FIG. 6 has a hollow structure with a cavity 74 inside. Even with this structure, it is possible to preferentially deform the shaft 72 of the sacrificial roller 70 when excessive tension is applied to the print medium 9.

[0059] Alternatively, a notch may be provided in the shaft 72 of the sacrificial roller 70. Alternatively, the shaft 72 of the sacrificial roller 70 may be made of a material that is more easily deformed than the shafts of the other driven rollers 12.

[0060] Furthermore, in the above embodiment, the printing device 1 has two sacrificial rollers 70. However, the number of sacrificial rollers 70 included in the plurality of driven rollers 12 may be one, or may be three or more. In other words, it is sufficient that at least one driven roller 12 among the plurality of driven rollers 12 is a sacrificial roller 70.

[0061] Furthermore, the printing device 1 in the above embodiment is equipped with four heads 21. However, the number of heads 21 equipped in the printing device 1 may be one to three, or five or more. For example, the printing device 1 may be equipped with a head 21 that ejects ink of a special color in addition to inks of the colors C, M, Y, and K.

[0062] Furthermore, the elements appearing in the above-described embodiments and modifications may be combined as appropriate within the scope of not causing any contradiction. [Explanation of symbols]

[0063] 1:Printing device 9:Print media 10: Transport mechanism 11: Drive roller 12: Driven roller 13: Encoder 15: Tension sensor 20:Printing Department 21: Head 30:Drying section 31: Heater 40: Inspection Department 41: Camera 50: Control unit 60: Housing 61: Loading entrance 62: Exit 70: Sacrificial Laura 71: Roller body 72: Shaft 73: Neck 74: hollow A1: Printing area A2: Drying area A3: Inspection area

Claims

1. a transport mechanism that transports a long strip of printing medium in a longitudinal direction; a head that ejects ink onto the print medium transported by the transport mechanism; a control unit that controls the transport mechanism and the head; Equipped with The transport mechanism includes: a drive roller that actively rotates by power output from a motor; a plurality of driven rollers that rotate in accordance with the movement of the printing medium; and A printing device, wherein at least one of the plurality of driven rollers is a sacrificial roller that is more easily deformed than the other driven rollers.

2. 2. The printing device according to claim 1, a housing having an inlet and an outlet for the print medium and accommodating the transport mechanism and the head therein; Furthermore, The printing device, wherein the sacrificial roller is located in the housing near the inlet or the outlet.

3. 3. The printing device according to claim 2, A printing device, wherein the sacrificial roller is a second driven roller from the carry-in entrance or the carry-out exit among the plurality of driven rollers.

4. 4. The printing device according to claim 1, a tension sensor for detecting the tension of the printing medium; Furthermore, The control unit extracts a fluctuation component of the tension corresponding to the sacrificial roller from the time series data of the tension output from the tension sensor, and detects deformation of the sacrificial roller based on the fluctuation component.

5. 5. The printing device according to claim 4, A printing device, wherein the diameter of the outer peripheral surface of the sacrificial roller that contacts the printing medium is neither an integer multiple nor an integral multiple of the diameter of the outer peripheral surface of the other driven roller that contacts the printing medium.

6. 4. The printing device according to claim 1, The sacrificial roller has a shaft extending along a central axis; The printing device, wherein the shaft has a constricted portion.

7. 4. The printing device according to claim 1, The sacrificial roller has a shaft extending along a central axis; The printing device, wherein the shaft has an internal cavity.

Images