JP2010111057A - Printing method and printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately release sagging of paper and to efficiently stabilize conveyance of roll paper. <P>SOLUTION: This printing method in a printer including a first motor for applying driving force for rotating a roll body wound with a printing medium, and a second motor for applying driving force for driving a conveying drive roller that conveys the printing medium, and a print head for jetting ink to the printing medium, includes adjusting tension applied to the printing medium by driving the first motor according to the end position of the printing medium. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a printing method and a printing apparatus.

  Among the ink jet printers, there is a type that uses a large paper having a paper size of A2 or larger. In such large-format ink jet printers, so-called roll paper is often used in addition to cut paper. In the following description, a so-called roll paper around which a paper is wound is referred to as a roll body, and a portion pulled out from the roll body is referred to as a paper. At present, the paper is pulled out from the roll body by rotating the transport roller by a paper feed motor (PF motor). The PF motor is controlled and driven by PID control. As a printer using such a roll body, there is one disclosed in Patent Document 1. Further, there are printers that perform PID control as shown in Patent Documents 2 to 4.

JP 2007-290866 A JP 2006-240212 A JP 2003-79177 A JP 2003-48351 A

By the way, the transport roller is usually set a certain distance away from the roll body mounted on the printer main body in the direction in which the paper is supplied, so that the paper drawn from the roll body is separated from the roll body and the transport roller. May loosen between. For example, when printing is started, the user pulls out a sheet from a roll body mounted on the printer body and sets it on a paper feed mechanism including a PF motor, a conveyance roller, and the like. The paper may loosen with the mechanism. In addition, after the paper is set in the paper feed mechanism, the paper may be back-fed (ie, rewound) for the cueing of the paper, but even at that time, the paper may be loosened. When the printing process is performed on the slack paper, the print image is disturbed and the image quality deteriorates. Therefore, usually, the user appropriately checks such slack, and when it is determined that the paper is slack, for example, the user manually rotates the roll body so that the slack of the paper is wound. As described above, in a printer using a roll body, there is a problem that it is necessary for the user to remove the slack of the paper manually, which is troublesome. Further, when the slack is missed or the slack cannot be sufficiently released, the printed image may be disturbed.
The present invention has been made based on the above-described circumstances, and provides a printing method and a printing apparatus that can appropriately release the slack of paper.

  The present invention includes a first motor that provides a driving force for rotating a roll body around which a printing medium is wound, a second motor that provides a driving force for intermittently driving a conveyance driving roller that conveys the printing medium, The present invention relates to a printing method using a print head that ejects ink onto the print medium.

  In the printing method described above, when the tension applied to the print medium when the print medium is conveyed by driving the second motor is unstable, the slip amount in the conveyance is also unstable, and the conveyance amount is inaccurate. It becomes. Therefore, in the present invention, the first motor is driven according to the leading end position of the print medium, thereby suppressing the fluctuation of the tension according to the end position of the print medium. Thereby, the print medium can be stably conveyed. In the present invention, driving refers to a state in which each motor actively generates a driving force, and is not limited to a state in which the driving unit of each motor is actually rotated by the driving force.

  Since the tension acting on the print medium and the slip amount of the print medium during conveyance correspond linearly, if the tension acting on the print medium can be set to a desired amount, the slip amount of the print medium during conveyance is set. The desired amount can be set. For this reason, it is desirable to drive the first motor so that the tension acting on the print medium becomes a designated tension corresponding to a desired slip amount. Further, since the appropriate slip amount and the tension for realizing the appropriate slip amount differ depending on the type of the print medium, the appropriate designated tension is set according to the type of the print medium. May be.

  By the way, when the printing apparatus includes a suction unit that holds the print medium with respect to the print head by sucking the print medium, a tension acting on the print medium is applied to the print medium with respect to the suction unit. This greatly depends on the relative position of the leading end position. Therefore, it is desirable to adjust the tension acting on the print medium by driving the first motor according to the position of the leading end of the print medium with respect to the suction portion.

  As an example of a specific method for realizing the adjustment as described above, the suction area of the print medium sucked by the suction unit is specified based on the position of the leading end of the print medium, and the suction area is determined according to the suction area. The first motor may be driven. According to the suction area, the normal force acting on the print medium and the frictional resistance can be grasped, and the tension fluctuation caused by the frictional resistance can be eliminated.

  The first motor may be driven according to the weight of the print medium unwound from the roll body. It is conceivable that the weight of the printing medium unwound from the roll body causes a change in tension. Therefore, the weight of the print medium unwound from the roll body may be grasped from the position of the leading end of the print medium, and the variation in tension due to the weight may be eliminated.

  Furthermore, the state of the tension acting on the print medium changes before and after the rear end of the print medium is detached from the roll body. However, after the rear end of the print medium is detached from the roll body, the tension acting on the print medium is adjusted even when the first motor that applies a driving force to the roll body is driven. I can't. That is, the slip amount cannot be made constant. For this reason, after the rear end of the print medium is detached from the roll body, it is desirable to change the drive amount of the second motor for transporting the print medium by a predetermined amount in anticipation of the variation of the slip amount.

  Furthermore, the technical idea of the present invention can be embodied not only by a specific printing method but also by a printing apparatus that executes the method. That is, the present invention can be specified as a printing apparatus having means corresponding to processing performed in each step of the above-described printing method. Of course, when the above-described printing apparatus reads the program and realizes each unit described above, the technical idea of the present invention is also applied to a program for executing a function corresponding to each unit and various recording media on which the program is recorded. Needless to say, can be realized. Needless to say, the printing apparatus of the present invention can be distributed not only by a single apparatus but also by a plurality of apparatuses.

Hereinafter, embodiments of the present invention will be described in the following order.
1. Printer configuration:
2-1. Overall processing:
2-2. Measurement process:
2-3. Estimation process:
2-4. Printing process:
2-5. Roll control processing:
2-6. Loosening treatment:
2-7. Modification 1:
2-8. Modification 2:

1. Configuration of Printer Hereinafter, a printer 10 as a printing apparatus (fluid ejecting apparatus) according to an embodiment of the present invention and control processing thereof will be described. Note that the printer 10 of the present embodiment is a printer for printing large format paper of, for example, JIS standard A2 or higher. The printer in this embodiment is an ink jet printer. The ink jet printer may be a device that employs any discharge method as long as it is a device that can print by discharging ink. In the following description, the lower side refers to the side where the printer 10 is installed, and the upper side refers to the side away from the installed side. Further, the side on which the paper P is supplied will be referred to as a supply side / rear side (rear end side), and the side on which the paper P is discharged will be described as a paper discharge side / front side (front side).

  FIG. 1 is a perspective view showing a configuration example of the appearance of a printer 10 according to an embodiment of the present invention. FIG. 2 is a diagram showing a relationship between a drive system using a DC motor and a control system in the printer 10 of FIG. In the case of this example, the printer 10 includes a pair of leg portions 11 and a main body portion 20 supported by the leg portions 11. The leg portion 11 is provided with a support column 12, and a rotatable caster 13 is attached to the caster support portion 14. Various types of internal devices are mounted on the main body 20 in a state of being supported by a chassis (not shown), and these are covered with an external case 21. As shown in FIG. 2, the main body 20 is provided with a roll drive mechanism 30, a carriage drive mechanism 40, and a paper transport mechanism 50 as a drive system using a DC motor.

  The roll driving mechanism 30 is provided on the roll mounting portion 22 present in the main body portion 20. As shown in FIG. 1, the roll mounting portion 22 is provided on the back side and the upper side of the main body portion 20, and by opening an opening / closing lid 23 that is one element constituting the outer case 21 described above, A roll body RP is mounted inside the roll body RP, and the roll body RP can be rotationally driven by the roll drive mechanism 30. Moreover, the roll drive mechanism 30 for rotating the roll body RP has a rotation holder 31, a gear wheel train 32, an RR motor 33, and a rotation detector 34 as shown in FIGS. FIG. 3 is a diagram showing an example of the external configuration of the rotary holder 31 and the RR motor 33. The rotating holders 31 are inserted from both ends of the hollow hole RP1 provided in the roll body RP, and a pair is provided to support the roll body RP from both ends.

  The RR motor 33 as a first motor gives a driving force (rotational force) via a gear train 32 to a rotary holder 31 a located on one end side of the pair of rotary holders 31. The rotation detector 34 uses a rotary encoder in this embodiment. Therefore, the rotation detection unit 34 includes a disk-shaped scale 34a and a rotary sensor 34b. The disk-shaped scale 34a has a light-transmitting part that transmits light and a light-shielding part that blocks light transmission at regular intervals along the circumferential direction. The rotary sensor 34b includes a light emitting element (not shown), a light receiving element (not shown), and a signal processing circuit (not shown) as main components.

  In this embodiment, pulse signals (A-phase ENC signal and B-phase ENC signal) whose phases are different from each other by 90 degrees as shown in FIG. 4 are input to the control unit 100 by the output from the rotary sensor 34b. The Therefore, it is possible to detect whether the RR motor 33 is in the normal rotation state or the reverse rotation state by the progress / delay of the phase. The main body 20 is provided with a carriage drive mechanism 40. The carriage drive mechanism 40 includes a carriage 41 and a carriage shaft 42 that are also part of the components of the ink supply / ejection mechanism, and includes a carriage motor, a belt (not shown), and the like.

  The carriage 41 includes an ink tank 43 for storing ink of each color (corresponding to fluid). The ink tank 43 is fixed to the front side of the main body 20 via a tube (not shown). Ink can be supplied from an ink cartridge (not shown) provided. Further, as shown in FIG. 2, a print head 44 (corresponding to a fluid ejecting head) capable of ejecting ink droplets is provided on the lower surface of the carriage 41. The print head 44 is provided with a nozzle row (not shown) associated with each ink, and a piezo element (not shown) is arranged in the nozzle constituting the nozzle row. By operating the piezo element, it is possible to eject ink droplets from the nozzles at the end of the ink passage.

  The carriage 41, the ink tank 43, a tube (not shown), the ink cartridge, and the print head 44 constitute an ink supply / ejection mechanism. The print head 44 is not limited to a piezo drive system using a piezo element. For example, a heater system that heats ink with a heater and uses the generated foam force, a magnetostriction system that uses a magnetostrictive element, and a mist that is controlled by an electric field. A mist method or the like may be employed. Ink filled in the ink cartridge / ink tank 43 may be mounted with any kind of ink such as dye-based ink / pigment-based ink.

  As shown in FIGS. 2, 5, etc., the paper transport mechanism 50 includes a transport roller pair 51, a gear wheel train 52, a PF motor 53, and a rotation detector 54. FIG. 5 is a diagram illustrating a positional relationship among the roll body RP, the transport roll pair 51, and the print head 44. The conveyance roller pair 51 includes a conveyance driving roller 51a and a conveyance driven roller 51b, and a sheet P (corresponding to roll paper) drawn from the roll body RP can be sandwiched between them. The PF motor 53 as the second motor gives a driving force (rotational force) to the transport driving roller 51a via the gear wheel train 52. Further, the rotation detection unit 54 of the present embodiment uses a rotary encoder, and similarly to the rotation detection unit 34 described above, includes a disk-like scale 54a and a rotary sensor 54b, and outputs a pulse signal as shown in FIG. Output is possible.

  Further, a platen 55 is provided on the paper discharge side with respect to the conveying roller pair 51, and the paper P is guided on the platen 55. The print head 44 is disposed so as to face the platen 55. The platen 55 is provided with a rectangular suction portion 55b (a region where suction force is effectively applied) in which a plurality of suction holes 55a are formed. On the other hand, the suction hole 55a is provided so as to be able to communicate with the suction fan 56. When the suction fan 56 is operated, air is sucked from the print head 44 side through the suction hole 55a. Thereby, when the paper P exists on the platen 55, the paper P can be sucked and held. In addition, the printer 10 includes various other sensors such as a paper width detection sensor 57 that detects the width of the paper P and a paper edge sensor 58 that detects the paper edge on the leading side in the printing direction of the paper P. A discharge unit 59 that hangs the paper P from the top side is provided on the top side of the platen 55.

  FIG. 6 is a block diagram illustrating a functional configuration example of the control unit 100. The control unit 100 receives output signals from the rotary sensors 34b and 54b, a linear sensor (not shown), a paper width detection sensor 57, a gap detection sensor (not shown), an operation panel of the printer 10, and the like. As shown in FIG. 2, the control unit 100 includes a CPU 101, a ROM 102, a RAM 103, an NVRAM 104, an ASIC 105, and a motor driver 106, which are connected to each other via a transmission path 107 such as a bus. The control unit 100 is connected to the computer COM. Then, the main control unit 110 as shown in FIG. 6 is obtained by the cooperation of these hardware and the ROM 102 and the stored software and / or data, or the addition of circuits and components for performing specific processing. Thus, the PF motor control unit 111 and the RR motor control unit 112 are realized.

  The PF motor control unit 111 of the control unit 100 controls the driving of the PF motor 53 so that the transport driving roller 51a rotates and the paper P is transported in the transport direction. Hereinafter, the direction of rotation of the PF motor 53 when the paper P is transported in the transport direction is referred to as a normal rotation direction. The RR motor control unit 112 as a control unit controls the driving of the RR motor 33 so that the paper P does not become slack. The direction of rotation for unwinding the paper P from the roll body RP is the forward rotation direction of the RR motor 33, and the direction of rotation for winding the paper P is the reverse rotation direction. The main control unit 110 controls operations of the PF motor control unit 111 and the RR motor control unit 112. The control unit 100 executes each process described later in cooperation with the main control unit 110, the PF motor control unit 111, and the RR motor control unit 112.

2-1. Overall Processing FIG. 7 shows a schematic flow of overall processing executed by the printer 10 of the present embodiment. In step S <b> 100, the control unit 100 detects that the roll body RP is mounted (replaced) on the roll mounting unit 22. For example, the mounting of the roll body RP on the roll mounting unit 22 may be detected by a sensor (not shown), or the mounting of the roll body RP may be detected in accordance with an operation of an operation panel (not shown). In the present embodiment, the operation panel (not shown) accepts that the roll body RP is mounted and the type of paper P wound around the roll body RP (for example, plain paper, glossy paper, matte paper). Shall. Information for identifying the type of the received paper P is stored in the NVRAM 104. Next, the control part 100 performs a measurement process in step S200. In this measurement process, the diameter D of the roll body RP immediately after the roll body RP is mounted and the roll static load (torque) when the roll body RP rotates are measured. Since this roll static load varies linearly according to the rotation speed of the roll body RP (paper P transport speed V), the roll static load Nhi during high-speed transport and the roll static load Nlo during low-speed transport are measured. Keep it. When the measurement process is completed, the roll static loads Nlo, Nhi and the diameter D are stored in the NVRAM 104.

  When the measurement process is completed, the printer is ready for printing, and an input of a print job from the computer COM is accepted in step S300. In step S400, print processing for the accepted print job is executed. When the printing process is completed, it is determined whether or not the loaded paper P of the roll RP is a plain paper (step S450). If the paper P is a plain paper, an estimation process is executed in step S500. In this estimation process, the diameter D of the roll body RP and the roll static loads Nlo and Nhi immediately after the printing process are acquired, and these are updated in the NVRAM 104. When the estimation process is completed, the process returns to step S300. On the other hand, if the loaded paper P of the roll body RP is not plain paper, the process returns to step S200 to execute measurement processing. That is, the roll static loads Nlo and Nhi and the diameter D are acquired by the measurement process and updated to the NVRAM 104.

  As described above, in the present embodiment, at the stage where the roll body RP is first attached, the measurement process is executed, and the roll static loads Nlo, Nhi and the diameter D stored in the NVRAM 104 are each time the printing process is completed. We are going to update. However, when the loaded paper P of the roll body RP is plain paper, the roll static loads Nlo, Nhi and the diameter D are obtained by the measurement process for the first time, and the roll static loads Nlo, Nhi and the diameter are obtained for the second and subsequent times. D is acquired by an estimation process. On the other hand, when the loaded paper P of the roll body RP is not plain paper, the roll static loads Nlo, Nhi and the diameter D are acquired by measurement processing every time. It should be noted that it is desirable to execute the slack eliminating process (step S700) in advance before the measurement process and the printing process as indicated by a broken line. Note that the printer 10 may transport the paper P other than in the printing process. For example, it may be considered that the paper P is transported during maintenance. Even when such an operation is performed, it is desirable to execute a measurement process or an estimation process in order to update the roll static loads Nlo, Nhi and the diameter D. Next, the measurement process will be described.

2-2. Measurement Process FIG. 8 shows the flow of the measurement process. In step S205, the control unit 100 acquires outputs from the rotary sensors 34b and 54b while the PF motor control unit 111 drives the PF motor 53 in the forward rotation direction. Only the PF motor 53 is driven in the forward direction. However, since the paper P of the roll body RP is conveyed according to the driving of the PF motor 53, the roll body RP and the RR motor 33 are also rotated in the forward direction. Will be.

  FIG. 9 shows an example of the outputs of the rotary sensors 34b and 54b in step S205. In the figure, the broken line indicates the output of the rotary sensor 54 b corresponding to the rotation amount of the PF motor 53, and the solid line indicates the output of the rotary sensor 34 b corresponding to the rotation amount of the RR motor 33. The horizontal axis indicates time, and the vertical axis indicates the count numbers Err and Epf of the rotary sensors 34b and 54b in step S205. The count numbers Err and Epf are the count numbers of the edges of the ENC signal described above and mean the rotation amounts of the rotary sensors 34b and 54b in step S205. As shown in FIG. 9, the PF motor 53 is driven so as to accelerate from the initial stage to the middle stage of driving, then gradually decelerate, and finally stop. Since the RR motor 33 is driven, the output of the rotary sensor 34b is the same.

In step S210, the count numbers Err and Epf of the rotary sensors 34b and 54b are acquired after a predetermined time has elapsed from the drive in step S205, and the diameter D of the roll body RP is calculated based on the count numbers. Here, since the extension and slip of the paper P are almost negligible, the transport amount ΔLpf of the paper P transported by the rotation of the PF motor 53 and the transport amount ΔLrr of the paper P transported by the rotation of the RR motor 33 in step S205. Can be considered the same. Further, the transport amounts ΔLpf and ΔLrr of the paper P are proportional to the respective count numbers Err and Epf by the rotary sensors 34b and 54b. When these proportional coefficients are k1 and k2, respectively, the following equation (1) is established.

ｋ１，ｋ３は既知の定数であるため、前記の（２）式を直径Ｄに関して解けば、カウント数Ｅｒｒ，Ｅｐｆから直径Ｄを算出することができる。ステップＳ２１５においては、算出された直径Ｄが正常な値であるかを判定し、正常である場合にはステップＳ２２０にて直径ＤをＮＶＲＡＭ１０４に記憶する。正常でない場合には、再度、ステップＳ２０５をやり直す。また、正常でない場合には、エラーを通知しつつ終了してもよい。 The proportional constant k1 related to the PF motor 53 is a constant corresponding to the reduction ratio of the gear train 52, the diameter, the circumferential ratio, and the like of the transport drive roller 51a. On the other hand, since the diameter D of the roll body RP decreases as the paper P is conveyed, the proportional coefficient k2 regarding the RR motor 33 is a coefficient proportional to the diameter D of the roll body RP. When the proportionality coefficient k2 is decomposed into a constant k3 (a constant corresponding to a reduction ratio, a circumferential ratio, etc. of the gear wheel train 32) and a diameter D, the above expression (1) is expressed as the following expression (2). The diameter D can be calculated.

Since k1 and k3 are known constants, the diameter D can be calculated from the count numbers Err and Epf by solving the equation (2) with respect to the diameter D. In step S215, it is determined whether the calculated diameter D is a normal value. If it is normal, the diameter D is stored in the NVRAM 104 in step S220. If not normal, step S205 is performed again. If not normal, the process may be terminated while notifying an error.

  In step S225, the RR motor control unit 112 drives the RR motor 33 in the forward rotation direction and feeds the paper P at a constant transport speed Vlo. Further, in step S225, the control unit 100 converts the duty of the PWM signal output from the RR motor control unit 112 to the RR motor 33 into torque during the period when the transport speed V of the paper P is stable at the transport speed Vlo. As a result, the roll static load Nlo is obtained. In the present embodiment, PID control with the conveyance speed Vlo as a target is performed, and the roll static load Nlo is acquired by converting the average value of the integral component of the PID control value into torque. Since the transport speed V of the paper P can be obtained by dividing the transport amount ΔLrr described above by time, PID control with the transport speed Vlo as a target can be performed. When driving the RR motor 33 to perform the measurement process (and estimation process), the PF motor 53 is stopped (outputs a current for maintaining the stop).

  In step S230, the RR motor control unit 112 drives the RR motor 33 in the forward rotation direction, and feeds the paper P at a constant transport speed Vhi (> Vlo). Then, during the period when the transport speed V of the paper P is stable at the transport speed Vhi, the duty value of the PWM signal output to the RR motor 33 by the RR motor control unit 112 is set as the roll static load Nhi, similarly to step S225. get. Here, the roll static loads Nlo and Nhi are values corresponding to loads necessary for rotating the roll body RP at a rotation speed corresponding to the conveyance speeds Vlo and Vhi against the rotation resistance (mainly frictional resistance). You can think of it.

ステップＳ２３５においてはロール静負荷Ｎｌｏ，Ｎｈｉの値が正常であるか否かを判断し、正常である場合にはステップＳ２４０においてロール静負荷Ｎｌｏ，ＮｈｉをＮＶＲＡＭ１０４に記憶し、測定処理を完了させる。正常でない場合には、再度、ステップＳ２３０からやり直す。以上説明した測定処理によれば、ロール体ＲＰの直径Ｄおよびロール静負荷Ｎｌｏ，Ｎｈｉを測定し、ＮＶＲＡＭ１０４に記憶することができる。なお、上述したとおり、ロール体ＲＰの用紙Ｐが普通紙でない場合には、印刷処理を実行するごとに測定処理が実行され、直径Ｄおよびロール静負荷Ｎｌｏ，Ｎｈｉは逐次更新されていくこととなる。次に、推定処理について説明する。 FIG. 10 shows an example of the relationship between an arbitrary transport speed V and a roll static load N. As shown in the figure, the roll static load N can be expressed by a linear function of the conveyance speed V. At least, if the duty values Nlo and Nhi at the conveyance speeds Vlo and Vhi are known, the roll static load N corresponds to an arbitrary conveyance speed V. The roll static load N can be calculated by the following equation (3).

In step S235, it is determined whether or not the roll static loads Nlo and Nhi are normal. If normal, the roll static loads Nlo and Nhi are stored in the NVRAM 104 in step S240, and the measurement process is completed. If not normal, the process starts again from step S230. According to the measurement process described above, the diameter D of the roll body RP and the roll static loads Nlo and Nhi can be measured and stored in the NVRAM 104. As described above, when the paper P of the roll body RP is not plain paper, the measurement process is executed every time the printing process is executed, and the diameter D and the roll static loads Nlo and Nhi are sequentially updated. Become. Next, the estimation process will be described.

2-3. Estimation Process FIG. 11 shows the flow of the estimation process. In step S305, the diameter D of the roll body RP currently stored in the NVRAM 104 is acquired. Currently, the diameter D of the roll body RP stored in the NVRAM 104 means the diameter D of the roll body RP before executing the immediately preceding printing process (hereinafter referred to as a reference diameter D0). As a condition for executing the estimation process as shown in FIG. 7, it is assumed that the paper P of the roll body RP is plain paper. In step S310, the transport amount ΔL (ΔLpf) of the paper P transported in the immediately preceding printing process is acquired. In each print job, since the print size in the transport direction is designated, the transport amount ΔL actually transported in the printing process can be acquired. Of course, the cumulative value of the count number of the rotary sensor 54b in the printing process may be converted into the transport amount ΔLpf by the above equation (1). In step S315, based on the correspondence (first correspondence CR1) between the diameter D of the roll body RP and the remaining amount L of the paper P wound around the roll body RP, the current diameter D of the roll body RP is determined. presume.

  FIG. 12 shows an example of the first correspondence relationship CR1 described above. In the figure, the vertical axis indicates the remaining amount L of the paper P wound around the roll body RP, and the horizontal axis indicates the diameter D of the roll body RP. As shown in the figure, the first correspondence relationship CR1 can be represented by a parabola (second-order function) having a diameter D of the roll body RP. In estimating the diameter D of the current roll body RP, first, the remaining amount L of the paper P corresponding to the reference diameter D0 of the roll body RP before executing the immediately preceding printing process acquired in step S305 (hereinafter referred to as a reference). (Represented as the remaining amount L1)) based on the first correspondence relationship CR1. Then, the current remaining amount L of the paper P (hereinafter referred to as the remaining amount L2) is calculated by subtracting the carry amount ΔL acquired in step S310 from the reference remaining amount L1. Further, the diameter D corresponding to the current remaining amount L2 of the paper P is calculated based on the first correspondence relationship.

  Thereby, the diameter D of the current roll body RP can be estimated. The function parameter that defines the first correspondence relationship (secondary function) CR1 is stored in advance in the ROM 102, and the parameter is read and used in step S315. In step S320, the estimated diameter D is updated and stored in the NVRAM 104. In the next step S325, the control unit 100 acquires the measured value w of the paper width by the paper width detection sensor 57. In step S330, the current roll body RP corresponds to the transport speeds Vlo and Vhi based on the correspondence (second correspondence CR2a and CR2b) between the diameter D of the roll body RP and the static static loads Nlo and Nhi. The roll static loads Nlo and Nhi when rotating at the rotation speed are estimated.

  FIG. 13 shows the second correspondence relationship CR2a, CR2b. In the figure, the vertical axis represents roll static loads Nlo and Nhi, and the horizontal axis represents the diameter D of the roll body RP. Second correspondence relations CR2a and CR2b (shown by solid lines) indicate the roll static loads Nlo and Nhi when the roll body RP around which the sheet P having the reference sheet width w0 is wound is driven at the conveyance speeds Vlo and Vhi, respectively. . As shown in the figure, the second correspondence relationship CR2a, CR2b can be represented by a parabola (quadratic function) having a diameter D of the roll body RP. This is because as the diameter D of the roll body RP decreases, the weight of the roll body RP decreases and the frictional resistance is reduced.

  Further, it can be considered that the roll static loads Nlo and Nhi are proportional to the paper width w. For example, in the case of a paper width w that is twice the reference paper width w0, the roll static loads Nlo and Nhi have twice the size of the roll static loads Nlo and Nhi as indicated by the broken line. When the roll static loads Nlo and Nhi with an arbitrary paper width w are obtained, the roll static loads Nlo and Nhi indicated by the solid line may be multiplied by the paper width ratio w / w0. Since the current diameter D of the roll body RP is acquired in step S315, roll static loads Nlo and Nhi (solid lines) corresponding to the diameter D are calculated in the second correspondence relationship CR2a and CR2b in step S330, respectively. Furthermore, the roll static loads Nlo and Nhi for the actual paper width w can be estimated by multiplying the paper width ratio w / w0 described above. In step S335, the roll static loads Nlo and Nhi estimated as described above are updated and stored in the NVRAM 104.

  The first correspondence relationship CR1 and the second correspondence relationships CR2a and CR2b are prepared based on theoretical formulas and preliminary experiments, but in the present embodiment, they are prepared only for plain paper. Therefore, estimation by the estimation process is possible only when the paper P of the mounted roll body RP is plain paper. When printing on plain paper, there is a great demand for shortening the time required for printing. Therefore, in this embodiment, estimation processing is performed on plain paper to reduce the time required for printing. Of course, the first correspondence relationship CR1 and the second correspondence relationships CR2a and CR2b are prepared for glossy paper and matte paper, and the first correspondence relationship CR1 and the second correspondence relationship CR2a corresponding to the type of the loaded paper P are prepared. , CR2b may be used for the estimation process. Whether the measurement process is performed or the estimation process is performed, the diameter D of the current roll body RP and the roll static loads Nlo and Nhi after execution of the printing process can be obtained, and the current (latest) roll body RP. Diameter D and roll static loads Nlo, Nhi can be stored in the NVRAM 104, and a printing process to be described later can be executed using this. Next, the printing process will be described.

2-4. Print Processing FIG. 14 shows the flow of print processing. As shown in the figure, the printing process is performed by first performing a paper edge position initialization process (step S405), and then alternately repeating a sheet conveyance process (step S410) and a head driving process (step S420). . In the paper edge position initialization process (step S405), the PF motor control unit 111 of the control unit 100 rotates the conveyance drive roller 51a to convey the paper P by a predetermined amount, and the paper edge sensor 58 detects the paper P. Detect the paper edge on the top of the transport When the paper edge can be detected, the paper P is conveyed until the paper edge reaches the print start position. By performing such a paper edge position initialization process, it is possible to always start printing from a certain position with respect to the paper edge of the paper P. Further, the main control unit 110 sets the position where the paper edge sensor 58 detects the paper edge as the reference position (x = 0), and the conveyance amount ΔL of the paper P conveyed after the paper edge sensor 58 detects the paper edge. Is stored in the NVRAM 104 as the paper edge position x.

  In the paper conveyance process (step S410), the PF motor control unit 111 of the control unit 100 controls the driving of the PF motor 53 so that the paper P is conveyed in the conveyance direction by rotating the conveyance driving roller 51a. In each paper transport process, the length of the paper P to be transported per unit time (corresponding to the above-described transport amount ΔL, expressed as the target transport amount ΔLt) is designated, and the transport for the target transport amount ΔLt is performed. Drive control is performed on the PF motor 53. In the present embodiment, when the necessary target carry amount ΔLt is designated based on the print data (print job), a speed mode of the carry speed V suitable for carrying the target carry amount ΔLt is selected. In this embodiment, the speed modes VM1 to VM4 can be selected, and PID control is performed with the maximum transport speed V being 5 ips, 3 ips, 1 ips, and 0.15 ips, respectively. Basically, the higher the target transport amount ΔLt, the faster the speed modes VM1 to VM4 are selected. In each paper transport process, when the transport of the target transport amount ΔLt is completed, the paper end position x is updated in the NVRAM 104 by adding the target transport amount ΔLt transported immediately before to the paper end position x described above.

  On the other hand, in the head driving process (step S420), while the paper P is stationary, the print head 44 is scanned in a direction orthogonal to the transport direction of the paper P, and ink is ejected from nozzles provided on the print head 44. Discharge drops. Thereby, ink dots can be formed on the paper P. By alternately performing the above-described paper conveyance processing and head driving processing, ink dots can be arranged in a two-dimensional direction, and a planar image can be formed on the paper P. When all the paper transporting processes and the head driving process are completed, the process returns to the main flow shown in FIG. 7 and the measurement process (in the case of other than plain paper) or the estimation process (in the case of plain paper) is executed. By the way, in this embodiment, the roll control process is executed in parallel with each sub-scan (step S410). Details of the roll control process (step S500) will be described below.

2-5. Roll Control Processing FIGS. 15 to 17 show the flow of roll control processing. As described above, since the paper conveyance process is performed alternately with the head driving process, the driving of the PF motor 53 is intermittent. The roll control process is executed in synchronization with each drive (stop-drive-stop) of the PF motor 53. The start timing of the roll control process may be after the driving of the PF motor 53 is stopped in the previous paper transporting process and before the driving of the PF motor 53 in the current paper transporting process. Although the end timing of the roll control process varies depending on the content of the process, the RR motor control unit 112 sets the output torque M of the RR motor 33 to 0 and applies a short brake to the RR motor 33 at the end of the roll control process. Accordingly, during the period when the PF motor 53 is not driven, the RR motor 33 is basically stopped and a predetermined braking force is generated. That is, the RR motor 33 is also intermittently driven similarly to the PF motor 53. In the short brake, the driving force is converted into the induced current by short-circuiting the motor coil, and the driving force is lost. In the roll control process, the duty of the PWM signal output to the RR motor 33 is updated, and the RR motor 33 is driven with an output torque M (driving force) corresponding to the duty.

  When the roll control process is started, in step S505, the RR motor control unit 112 acquires the target transport amount ΔLt in the (current) paper transport process (step S410) performed in synchronization, and the same selection method as the paper transport process To select the speed mode VM1 to VM4. That is, the same speed modes VM1 to VM4 as those in the paper conveyance process (step S410) performed in parallel are selected. In step S510, the RR motor control unit 112 reads the diameter D of the roll body RP, the roll static loads Nlo and Nhi, and the type of the paper P from the NVRAM 104. That is, the diameter D, the roll static loads Nlo and Nhi, and the type of paper P immediately before the printing process currently being executed are acquired. In step S 512, the paper edge position x of the paper P is acquired from the NVRAM 104. In step S515, the designated tension F corresponding to the type of paper P acquired in step S510 is acquired. Strictly speaking, the unit designated tension f per unit width is acquired, and the unit designated tension f is multiplied by the paper width w to obtain the designated tension F = f × w.

  FIG. 18 schematically illustrates the concept of the designated tension F. In the drawing, the relationship among the roll body RP, the transport roll pair 51, and the paper P is shown. In the paper transport process, the PF motor control unit 111 drives the transport driving roller 51a (not driving the RR motor 33), so that the paper P is transported at a predetermined transport speed V. Then, the roll body RP is driven to rotate forward so as to be pulled by the paper P. However, the torque of the roll static load N for the rotation of the roll body RP is the driving shaft of the RR motor 33 (the roll body RP). It occurs around the rotation axis. Assuming that the force generated by the torque on the sheet P positioned on the surface of the roll body RP is the resistance force T1, the resistance force T1 is obtained by the following equation (4) from the balance of moments about the rotation axis of the roll body RP. Can do.

なお、ｋ４は比例定数であり、ロール体ＲＰの回転軸の径等に基づいて特定できる。ところで、搬送速度Ｖと、当該搬送速度Ｖにてロール体ＲＰを回転さする際に生じるロール静負荷Ｎとの関係は、予め実行した測定処理または推定処理で得られたロール静負荷Ｎｌｏ，Ｎｈｉと前記の（３）式によって特定することができる。従って、各搬送速度ＶでＲＲモータ３３を駆動させることなく、任意の搬送速度Ｖで用紙Ｐを搬送する場合に生じる抵抗力Ｔ１を特定することができる。

In addition, k4 is a proportionality constant and can be specified based on the diameter of the rotating shaft of the roll body RP and the like. By the way, the relationship between the conveyance speed V and the roll static load N generated when the roll body RP is rotated at the conveyance speed V is based on the roll static loads Nlo and Nhi obtained by the measurement process or the estimation process executed in advance. And the above equation (3). Therefore, it is possible to specify the resistance force T1 generated when the paper P is transported at an arbitrary transport speed V without driving the RR motor 33 at each transport speed V.

図１９は、吸引部５５ｂと用紙Ｐとの関係を模式的に示している。図１９に示すように、前記の（５）式のｘは、紙端センサ５８の紙端検出位置を基準（０）とした用紙Ｐの紙端の位置を示している。ｘ₀，ｘ₁は、それぞれ紙端センサ５８の紙端検出位置を基準とした吸引部５５ｂの搬送方向両端の位置を示している。また、前記の（５）式において、吸引ファン５６が作動することにより吸引部５５ｂの単位面積あたりに生じる吸引力をｎとし、吸引部５５ｂと用紙Ｐとの間の摩擦係数をμ₁としている。摩擦係数μ₁は、ＲＯＭ１０２において各用紙Ｐの種類ごとに異なる値が記憶されている。 Further, not only the rotational resistance of the roll body RP but also the frictional resistance generated between the platen 55 and the paper P occurs when the transport driving roller 51a transports the paper P. The resistance force T2 generated by the frictional resistance generated between the platen 55 and the paper P can be expressed by the following equation (5).

FIG. 19 schematically shows the relationship between the suction portion 55b and the paper P. As shown in FIG. 19, x in the above equation (5) indicates the position of the paper edge of the paper P with the paper edge detection position of the paper edge sensor 58 as the reference (0). x ₀ and x ₁ indicate positions at both ends in the transport direction of the suction portion 55b with reference to the paper edge detection position of the paper edge sensor 58, respectively. Further, in the above equation (5), a suction force is n generated per unit area of the suction portion 55b, and the coefficient of friction between the suction portion 55b and the sheet P and mu ₁ and by the suction fan 56 is operated . As the friction coefficient μ ₁ , a different value is stored for each type of paper P in the ROM 102.

In the case of x ₀ > x, the suction area where the suction part 55b and the paper P are in contact with each other is 0, and naturally no resistance force T2 is generated between them. When x ₁ >x> x ₀ , the suction area (hatching) where the suction unit 55b and the paper P come into contact is w × (x−x ₀ ), and the suction area is multiplied by the suction force n per unit area. Vertical drag will occur. Further, the resistance T2 is obtained by multiplying the vertical effect by the friction coefficient μ ₁ . When the position of the paper edge is x _1> x> x _0, the more paper edge is advanced in the conveying direction downstream, the suction area of the suction portion 55b and the sheet P is in contact increases linearly, the resistance force T2 Will increase. Further, when the x> x _1, suction area of the suction portion 55b and the sheet P is in contact becomes constant at wx _1, resistance force T2 is also constant.

前記の（６）式が示すように、用紙Ｐを搬送する間にＲＲモータ３３を正転（Ｍ＞０）させることにより、用紙Ｐに作用する抵抗力Ｔ１を軽減することができる。なお、出力トルクＭにより軽減され抵抗力Ｔ１の大きさ（調整量）は、ｋ４×Ｍ／Ｄとなる。反対に、ＲＲモータ３３に負の出力トルクＭ（逆転方向）を与えた場合には、抵抗力Ｔ１を増大させることができる。 Next, consider a case where the RR motor 33 is driven. When the RR motor control unit 112 performs PWM output to the RR motor 33 and the RR motor 33 generates output torque M in the forward rotation direction, the output torque M from the roll static load N around the rotation axis of the roll body RP. The torque obtained by subtracting is applied. In this case, the following formula (6) can be obtained based on the formula (4).

As indicated by the above equation (6), the resistance force T1 acting on the paper P can be reduced by rotating the RR motor 33 forward (M> 0) while the paper P is being conveyed. The magnitude (adjustment amount) of the resistance force T1 that is reduced by the output torque M is k4 × M / D. Conversely, when a negative output torque M (reverse direction) is applied to the RR motor 33, the resistance force T1 can be increased.

  When the transport driving roller 51a transports the paper P, the resultant force of the resistance forces T1 and T2 becomes the resistance of transporting the paper P, and the transport driving roller 51a transports the paper P against the resultant force. Become. That is, when the transport driving roller 51a transports the paper P, the resultant force (T1 + T2) of the resistance forces T1 and T2 acts on the paper P as a tension T (= T1 + T2). Here, if the tension T is too large, the slip amount between the transport driving roller 51a and the paper P increases, and the intended transport amount ΔL cannot be realized. The slip amount is proportional to the tension T. On the other hand, when the tension T is too small, the roll body RP unintentionally rotates forward to cause the paper P to be slack. Therefore, it is necessary to manage the tension T to an appropriate magnitude.

前記の（７）式により、指定張力Ｆを実現するために必要なＲＲモータ３３の出力トルクＭを算出することができる。図１８において、抵抗力Ｔ２の大きさを矢印で模式的に示しているが、ｘ₀＞ｘの場合は抵抗力Ｔ２が０となる。ｘ₁＞ｘ＞ｘ₀の場合は、抵抗力Ｔ２の大きさが（ｘ−ｘ₀）に比例して変動することとなる。さらに、ｘ＞ｘ₁の場合は、抵抗力Ｔ２は一定の大きさとなる。このように、抵抗力Ｔ２が紙端の位置ｘに応じて変動することとなるが、前記の（７）式によれば紙端の位置ｘに依存することなく、指定張力Ｆを実現するための出力トルクＭを得ることができる。なお、前記の（５）で使用されるロール体ＲＰの直径Ｄとロール静負荷Ｎｌｏ，Ｎｈｉは各印刷処理の後に更新されているため、出力トルクＭを正確に計算することができる。

Therefore, in this embodiment, the target tension T value is set as the designated tension F (= T1 + T2). Since the total of the resistance forces T1 and T2 obtained by the equations (5) and (6) is the designated tension F, the relationship of the following equation (7) can be obtained.

The output torque M of the RR motor 33 necessary for realizing the specified tension F can be calculated from the above equation (7). In FIG. 18, the magnitude of the resistance force T2 is schematically indicated by an arrow. However, when x ₀ > x, the resistance force T2 is zero. For x _1> x> x _0, the magnitude of the resistance force T2 is possible to vary in proportion to (x-x _0). Further, when x> x ₁ , the resistance force T2 has a constant magnitude. As described above, the resistance force T2 varies depending on the paper edge position x. According to the above equation (7), the specified tension F is realized without depending on the paper edge position x. Output torque M can be obtained. Since the diameter D of the roll body RP and the roll static loads Nlo and Nhi used in (5) are updated after each printing process, the output torque M can be calculated accurately.

  Further, since the duty value (Duty) of the PWM signal for generating the output torque M is proportional to the output torque M as shown in the above equation (8), the control for realizing the designated tension F is controlled by the RR motor. It can be performed by the control unit 112. Note that k5 corresponds to a proportionality constant for normalizing the duty. Since the mechanical characteristics of the paper P differ depending on the type of the paper P, the designated tension F is prepared for each type of the paper P and is stored in the ROM 102 in advance. Therefore, in step S515, the designated tension F corresponding to the type of paper P acquired in step S510 can be obtained. Since the friction coefficient varies depending on the type of the paper P, the slip amount corresponding to the tension T also varies. Therefore, the designated tension F for realizing an appropriate slip amount is set according to the friction coefficient of each paper P. Further, in the case of thick paper P, a large force is required for deformation for unwinding from a wound state onto a flat surface, and the designated tension F is set to be larger than that of the thin paper P. desirable.

  20A to 20D show examples of the relationship among the designated tension F, the roll static load N, and the output torque M. As shown in FIG. 20D, when the roll static load N is small and the designated tension F is large, the output torque M for realizing the designated tension F may be negative. In this case, by outputting the output torque M (M <0) in the reverse direction, the load around the rotation axis of the roll body RP is increased. In step S520, a control parameter set corresponding to the speed modes VM1 to VM4 specified in step S505 is acquired from the ROM 102. The ROM 102 stores a parameter table PT in which control parameter sets are stored for the respective speed modes VM1 to VM4.

  FIG. 21 shows an example of the parameter table PT. In the figure, the parameter table PT includes, as control parameters, a transport speed upper limit Vu, a transport amount limit value α, a self-running braking ratio b, a control transfer transport speed Vs, and a control end transport speed Vf for each of the speed modes VM1 to VM4. The initial tension Ts is stored. If the control parameter set corresponding to the speed modes VM1 to VM4 can be acquired, the parameters necessary for the roll control process can be acquired.

  In step S525, a predetermined time before the timing when the PF motor control unit 111 starts driving the transport driving roller 51a in the paper transport process (step S410) performed in synchronization (for example, several msec before, illustrated as ta). And waits until a predetermined time ta. During this time, the RR motor control unit 112 sets the output torque M (Duty) of the RR motor 33 to 0 and applies a short brake to the RR motor 33. When the predetermined time has elapsed, in step S530, it is determined whether or not the output torque M for realizing the designated tension F at the transport speed V = 0 is positive. Specifically, the roll static load N at the transport speed V = 0 is calculated by substituting the transport speed V = 0 into the above equation (3). Then, the output torque M of the RR motor 33 is calculated by substituting the roll static load N and the designated tension F into the equation (5). Then, it is determined whether or not the output torque M is positive.

  In step S530, when it is determined that the output torque M for realizing the designated tension F is positive at the transport speed V = 0, that is, the roll body RP is rotated forward in order to relax the tension T to the designated tension F. Processing in the case of driving in the direction (steps S535 to S645: hereinafter referred to as normal rotation control processing) will be described. The forward rotation control process is a loop process in which the RR motor control unit 112 updates the duty output to the RR motor 33 during the next minute time Δt each time a minute time Δt synchronized with a predetermined clock signal elapses. . Further, the normal rotation control process is divided into three control states of an initial control state, a middle-term control state, and a late-stage control state according to the stage of the process, and the duty is updated by different methods. The start timing of the normal rotation control process is a predetermined time before the PF motor control unit 111 starts driving the transport driving roller 51a.

  In step S535, the control state is set to the initial control state. In step S540, the elapse of a predetermined minute time Δt is awaited. In the next step S545, the transport speed V of the paper P by the roll body RP during the last minute time Δt is calculated. The transport speed V can be obtained by calculating the transport amount ΔLrr in the minute time Δt by the above equation (2) and further dividing the transport amount ΔLrr by the minute time Δt. In step S550, the conveyance amount ΔLrr of the paper P conveyed by the roll body RP after the start of the normal rotation control process is calculated. Here, the transport amount ΔLrr is calculated by substituting the count number Err of the rotary sensor 34b from the start of the forward rotation control process to the present into the above equation (2).

  In step S555, the target transport amount ΔLt in the paper transport process (step S410) performed in synchronization is multiplied by the transport amount limit value α acquired from the parameter table PT by the current transport speed V and the encoder cycle (time). The upper limit value of the transport amount is calculated by adding the values. And it is determined whether the said conveyance amount upper limit is larger than conveyance amount (DELTA) Lrr. If the transport amount ΔLrr is larger, a short brake is applied to the RR motor 33 in step S560, and the roll control process (forward rotation control process) is terminated. Thereby, the RR motor 33 is in a state in which the short brake is applied until the next roll control process is started. That is, when the transport amount ΔLrr by the roll body RP is larger than the target transport amount ΔLt that the transport drive roller 51a is supposed to transport, slack occurs in the paper P between the transport drive roller 51a and the roll body RP. Conceivable. Therefore, in such a case, a short brake is applied to the RR motor 33 so that no further slack is generated. Further, a different carry amount limit value α can be set according to each speed mode VM1 to VM4, and an upper limit value of the carry amount ΔLrr suitable for the speed modes VM1 to VM4 can be set. In the present embodiment, the transport amount limit value α having the same value is set for each of the speed modes VM1 to VM4, but may be set to a different value.

  In step S565, it is determined whether or not the conveyance speed V calculated in step S545 is smaller than the control end conveyance speed Vf acquired from the parameter table PT, and whether the control state is the middle period control state or the latter period control state. If the transport speed V is lower than the control end transport speed Vf and the control state is the middle-term control state or the latter-stage control state, a short brake is applied to the RR motor 33 in step S560, and the roll control process (forward rotation) Control processing) is terminated. When the conveyance speed V is lower than the control end conveyance speed Vf in the medium-term control state or the latter-stage control state other than the initial control state corresponding to the driving driving roller 51a before driving or the initial driving state, the driving of the conveying driving roller 51a is decelerated. It can be considered that it is at the end of or has already stopped.

  In such a case, when the output torque M that causes the roll body RR to rotate forward is output to the RR motor 33, the RR motor 33 rotates forward normally, and the paper P moves between the transport drive roller 51a and the roll body RP. Looseness will occur between them. Therefore, when the conveyance speed V is lower than the control end conveyance speed Vf, a short brake is applied and the roll control process is terminated. As shown in FIG. 21, the control end conveyance speed Vf is set to a small value for the speed mode VM4 in which the maximum conveyance speed V is small. In the speed mode VM4, since the transport speed V can be reduced even during a period other than when the drive of the transport drive roller 51a is about to stop, the roll control process ends at an unintended timing by reducing the control end transport speed Vf. Can be prevented.

  In step S570, in the paper conveyance process (step S410) performed in synchronization, the PF motor control unit 111 determines whether a predetermined threshold time has elapsed from the drive timing (drive start or drive end) of the conveyance drive roller 51a. If the predetermined threshold time or more has elapsed, a short brake is applied in step S560, and the roll control process is terminated. Thereby, it can prevent that the roll body RP drives at an abnormal timing. For example, it is possible to prevent the roll body RP from being driven by the user touching the paper P during the head driving process. As described above, in steps S555, S565, and S570 of the present embodiment, the stop condition of the roll control process (forward rotation control process) is determined every time the minute time Δt elapses. A short brake is applied to 33.

  In step S575, it is determined whether or not the transport speed V calculated in step S545 exceeds the transport speed upper limit Vu. As shown in FIG. 21, the transport speed upper limit Vu is 110% of the maximum transport speed V in each of the speed modes VM1 to VM4. Thereby, it is possible to determine whether or not the conveyance speed V of the paper P by the roll body RP is faster than the maximum conveyance speed V of the paper P by the planned conveyance drive roller 51a. When the transport speed V of the paper P by the roll body RP is faster, there is a possibility that the paper P between the transport driving roller 51a and the roll body RP may be slackened. The output torque M to be output by the RR motor 33 is set to 0 (step S580). That is, the duty of the PWM signal output to the RR motor 33 during the next minute time Δt (hereinafter referred to as setting duty) is set to zero.

  In step S585, it is determined whether the current control state is any one of the initial control state, the medium-term control state, and the late-stage control state, and the transition process is branched according to the result. Since the initial control state is set at the first stage, the process proceeds to step S605 corresponding to the initial control state. Hereinafter, processing in the initial control state will be described. In step S605, the initial tension Ts is set as the designated tension F, and output torque M and Duty for applying the initial tension Ts to the paper P are calculated. Specifically, the roll static load N at the transport speed V is calculated by substituting the transport speed V into the equation (3). Then, the output torque M of the RR motor 33 is calculated by substituting the roll static load N and the initial tension Ts into the equation (5).

  Further, the duty for obtaining the output torque M is calculated by the above equation (6), and the duty is set as the setting duty of the PWM signal output to the RR motor 33 during the next minute time Δt. As shown in FIG. 21, the initial tension Ts is a large value for the slowest speed mode VM4 and a small value for the other speed modes VM1 to VM3. In the speed modes VM1 to VM3 in which the initial tension Ts is small from the relationship of the above expression (5), a larger output torque M is output. In step S610, it is determined whether or not the transport speed V calculated in step S545 exceeds the control transfer transport speed Vs acquired from the parameter table PT. If the transport speed V exceeds the control transition transport speed Vs, the control state is shifted to the medium-term control state (step S615). In step S620, it is determined whether or not the driving of the transport driving roller 51a in the paper transporting process (step S410) performed in synchronization is finished. If the driving of the transport driving roller 51a has been completed, the control state is shifted to the late control state (S625). The process specific to the initial control state is thus completed.

  In step S630, it is determined whether the set duty is between a predetermined lower limit value and an upper limit value. If the set duty is smaller than the lower limit value, the set duty is corrected to the lower limit value (step S635). Similarly, when the set duty is larger than the upper limit value, the set duty is corrected to the upper limit value (step S640). By doing so, it is possible to prevent the absolute value from becoming an abnormally large setting duty, and to prevent the RR motor 33 from running away. In step S645, the RR motor control unit 112 outputs the set duty PWM signal to the RR motor 33, and the process returns to step S540. In step S540, the passage of the minute time Δt is again waited, and the subsequent processing is executed according to the transport speed V and the like at the minute time Δt.

  Next, processing in the medium-term control state will be described. If it is determined in step S585 that the current control state is the mid-term control state, in step S650, output torque M and Duty for realizing the designated tension F at the conveyance speed V calculated in step S545 are calculated. Specifically, the roll static load N is calculated by substituting the transport speed V calculated in step S545 into the above equation (3), and the roll static load N and the specified tension F are further expressed in the above equation (7). By substituting, the output torque M of the RR motor 33 is calculated. Further, the duty can be calculated by substituting the output torque into the equation (8). The calculated duty is set as the setting duty. Note that, when calculating the output torque M by the equation (7), the paper edge position x acquired from the NVRAM 104 in step S512 is used. Therefore, the output torque M that realizes the designated tension F can be calculated under the condition that the frictional resistance T2 between the paper P and the platen 55 according to the current position of the paper edge P acts.

  Thus, the process unique to the medium-term control state is completed, and the processes after step S620 are executed. That is, if the setting duty can be set, it is determined in step S620 whether or not the driving of the transport driving roller 51a in the paper transport process (step S410) performed in synchronization is completed. If the driving of the transport driving roller 51a has been completed, the control state is shifted to the late control state (step S625). Further, if necessary, the setting duty is corrected in steps S635 and S640, and the final setting duty PWM signal is output to the RR motor 33 in step S645.

Next, processing in the late control state will be described. If it is determined in step S585 that the current control state is the late control state, in step S655, the output torque M and Duty for realizing the designated tension F at the transport speed V calculated in step S545 are calculated. Specifically, the roll static load N is calculated by substituting the transport speed V calculated in step S545 into the above equation (3), and the roll static load N and the specified tension F are further expressed in the above equation (7). By substituting, the output torque M of the RR motor 33 is calculated. Again, the paper edge position x obtained from the NVRAM 104 in step S512 is used. Therefore, the output torque M that realizes the designated tension F can be calculated under the condition that the frictional resistance T2 between the paper P and the platen 55 according to the current position of the paper edge P acts. Further, the duty is calculated by substituting the output torque into the following equation (9). Then, the calculated duty is set as the setting duty.

  In the equation (9), the duty that is reduced by the ratio of the braking ratio b during self-running obtained from the parameter table PT from the duty obtained in the equation (8) is calculated. By doing in this way, braking according to the self-running braking ratio b can be performed. As described above, the process specific to the late control state is completed, and the processes after step S630 are executed. That is, if necessary, the setting duty is corrected in steps S635 and S640, and the final setting duty is output to the RR motor 33 in step S645.

  On the other hand, if it is determined in step S530 that the output torque M for realizing the designated tension F is negative at the conveyance speed V = 0, that is, the roll body RP is reversed to compensate the tension T to the designated tension F. Processing in the case of driving in the direction (hereinafter referred to as reverse rotation control processing) will be described. The reverse rotation control process is also a loop process in which the RR motor control unit 112 updates the duty output to the RR motor 33 during the next minute time Δt each time a minute time Δt synchronized with a predetermined clock signal elapses. In step S660, the process waits until the PF motor control unit 111 drives the transport driving roller 51a by the paper transport process (step S410) performed in synchronization. Then, at the same time when the conveyance drive roller 51a starts driving, measurement of the minute time Δt is started in step S665, and the process waits for the minute time Δt. During this time, the short brake of the RR motor 33 is continued. In the normal rotation control process, the conveyance drive roller 51a measures the minute time Δt from a predetermined time before the start of driving and outputs the set duty every minute time Δt, whereas in the reverse rotation control process, the conveyance drive roller 51a. However, it is different in that it waits until the drive is started and starts measuring the minute time Δt simultaneously with the start of the drive.

  In step S670, it is determined whether or not the PF motor control unit 111 has stopped driving the transport driving roller 51a in the paper transport process (step S410) performed in synchronization. If it is stopped, the reverse rotation control process (roll control process) is terminated, and a short brake is applied to the RR motor 33 (step S675). On the other hand, when the transport driving roller 51a continues to drive, the transport speed V of the paper P by the roll body RP during the immediately preceding minute time Δt is calculated in step S680 as in step S545. In step S685, the output torque M and Duty for realizing the designated tension F at the conveyance speed V calculated in step S680 are calculated in the same procedure as in step S605. Then, the calculated duty is set as the setting duty, and the PWM signal of the setting duty is output to the RR motor 33 (step S690). When the above process is completed, the process returns to step S665, the minute time Δt is again passed, and the same process is repeated. Next, the operation by the roll control process described above will be described.

  22A and 22B show the transition of the driving speed of the RR motor 33 by the roll control process in comparison with the driving speed (driving pattern) of the PF motor 53. FIG. 22A shows an operation example of the forward rotation control process, and FIG. 22B shows an operation example of the reverse rotation control process. First, in the initial control state of the forward rotation control process, the PWM signal of the setting duty for realizing the initial tension Ts is output to the RR motor 33 from the predetermined time ta before the driving of the PF motor 53. . Therefore, the RR motor 33 is driven in the forward direction before the PF motor 53. Thus, by driving the RR motor 33 prior to the PF motor 53, backlash (play) generated in the gear train 32 (drive member) or the like when the RR motor 33 was stopped last time is prevented. It is eliminated, and appropriate tension control can be realized at the stage where the PF motor 53 starts driving.

  For example, the amount of backlash (conveyed amount necessary for eliminating) when driving in each speed mode VM1 to VM3 is investigated, and the amount of backlash is eliminated when the PF motor 53 starts driving. It is desirable to set the initial tension Ts and the control transfer transport speed Vs so that the transport amount ΔLrr (corresponding to the hatching area in the figure) can be obtained. In the present embodiment, a large initial tension Ts is set for the slowest speed mode VM4, and a small initial tension Ts is set for the other speed modes VM1 to VM3. In the speed modes VM1 to VM3 in which the initial tension Ts is small from the relationship of the expression (5), a strong output torque M (second driving force, initial driving force) is output first. Thus, backlash can be quickly eliminated in the speed modes VM1 to VM3. Since the forward rotation of the roll body RP is promoted by the strong output torque M, it is possible to respond (follow) to the rapid acceleration in the speed modes VM1 to VM3.

  In the initial control state, as time elapses, the roll body RP may actively start normal rotation depending on the magnitude of the output torque M of the RR motor 33. Further, when the driving of the transport driving roller 51a is started in the initial control state (before the transport speed V reaches the control transition transport speed Vs), the roll body RP actively starts normal rotation in the initial control state. It is also possible. In any case, as time elapses, the driving speed of the RR motor 33 in the forward rotation direction increases, and at a certain stage, the conveyance speed V exceeds the control transfer conveyance speed Vs and shifts to the medium-term control state. It will be. In the medium-term control state, since the output torque M (first driving force) for applying the designated tension F to the paper P is output by the RR motor 33, the tension T acting on the paper P is set as the designated tension F. And abnormal slip can be prevented. Further, since the output torque M (first driving force) is output by the RR motor 33 in consideration of the resistance force T2 that varies depending on the paper edge position x, the frictional resistance corresponding to the paper edge position x is increased. Regardless of the fluctuation, it is possible to realize the conveyance of the paper P with high accuracy.

  Note that since the output torque M of the RR motor 33 is not set based on the driving speed of the RR motor 33, the transport speed V by the roll body RP is the maximum transport speed upper limit assumed in the speed modes VM1 to VM3. It may exceed Vu. In the present embodiment, the setting duty is forcibly set to 0 when the conveyance speed V exceeds 110% of the conveyance speed upper limit Vu corresponding to each of the speed modes VM1 to VM3 in the middle period control state and the latter period control state. I am trying to brake temporarily. Thereby, it is possible to prevent the paper P from being slackened due to excessive conveyance by the roll body RP. While the medium-term control state is continued for a while, the driving of the PF motor 53 is stopped, and the state shifts to the late-stage control state. In this late control state, the paper P is not pulled by the driving of the PF motor 53, so it can be considered that the roll body RP is self-propelled by inertia. If the roll body RP continues normal rotation even though the driving of the PF motor 53 is stopped, the paper P becomes slack. In the present embodiment, the set duty is calculated according to the above equation (7) in the late control state, thereby preventing the roll body RP from self-running and preventing the paper P from slackening.

  According to the equation (9), it is possible to set the output torque M (third driving force) in the forward rotation direction that is reduced by the ratio of the braking ratio b during self-running. That is, by making the output torque M in the forward rotation direction more conservative than in the mid-term control state, a braking force is generated, and the self-running of the roll body RP is stopped early. The self-running braking ratio b can be set to different values depending on the speed modes VM1 to VM4. In this embodiment, the self-running braking ratio b increases as the speed increases. The higher the speed, the longer the braking distance. However, the higher the speed, the larger the self-running braking ratio b, so that the braking distance in the high speed speed modes VM1 and VM2 can be suppressed. Therefore, the transport amount ΔLrr of the paper P transported by the rotation of the RR motor 33 can be prevented from being excessive with respect to the transport amount ΔLpf of the paper P transported by the rotation of the PF motor 53, and the slack of the paper P can be prevented. Can be prevented.

  When the driving of the PF motor 53 is also stopped and the rotation of the RR motor 33 is braked, the RR motor 33 gradually decelerates, and the transport speed V by the roll body RP gradually falls below the control end transport speed Vf. At that stage, the forward rotation control process is terminated and a short brake is applied to the RR motor 33. This short brake is maintained until the set duty is output in the next roll control process. By the way, when the conveyance amount ΔLrr in the initial control state or the medium-term control state is large, it is conceivable that the conveyance amount ΔLrr cannot be sufficiently suppressed by braking with the self-running braking ratio b in the latter-stage control state. Therefore, in this embodiment, the transport amount ΔLrr from the start of the roll control process by the roll body RP is substituted for the transport amount limit value α into the target transport amount ΔLt of the paper transport process that is performed synchronously in the equation (2). Even when the transport amount obtained by adding the transport amount is larger than the transport amount threshold, the short brake is applied to the RR motor 33 at that time, and the forward rotation control process is terminated. By doing so, even before the roll body RP decelerates, the driving of the RR motor 33 can be stopped, the excessive transport amount ΔLrr can be prevented, and the slack of the paper P can be prevented.

  On the other hand, in the reverse rotation control process, the output torque M is output in the reverse direction by the RR motor 33 as the PF motor 53 starts to be driven, and the output torque M is output in the reverse direction by the RR motor 33 as the PF motor 53 stops driving. Stops. During the reverse rotation control process, the output torque M for causing the designated tension F to act on the paper P is always output by the RR motor 33. In the reverse rotation control process, since the RR motor 33 is not driven before the PF motor 53 is driven, the driving of the roll body RP is basically driven. The reverse rotation control process is executed when it is determined that the output torque M for realizing the designated tension F is negative at the conveyance speed V = 0, and the roll body is used to compensate for the insufficient tension T. This is a process for applying an output torque M for driving the RP in the reverse direction. When the output torque M that drives the roll body RP in the reverse direction is given, the slack of the paper P does not occur unlike the normal rotation control process. In addition, since the tension is originally low, the roll body RP is driven n times before the start of driving the PF motor 53 to eliminate backlash or assist the driving of the PF motor 53 by the roll body RP self-running. There is little need to do. Therefore, it can be a simple process.

  As described above, the roll control process is executed only during the driving of the PF motor 53, immediately before the driving, and immediately after the driving, so that the RR motor 33 outputs the output torque M that is not zero. In other periods, the RR motor 33 is short-circuited. The RR motor 33 is driven in order to adjust the tension T of the paper P and to optimize the slip amount at the time of transport. However, in the period when the PF motor 53 is not driven and the paper P is not transported, the slip is originally performed. It can be considered that there is no need to adjust the tension T of the paper P. Therefore, by performing the roll control process only during the driving of the PF motor 53, immediately before the driving, and immediately after the driving, it is possible to suppress unnecessary power consumption while adjusting the appropriate tension T. It is also possible to secure resources such as the CPU 101 when the roll control process is not executed.

2-6. Sag Removal Processing FIG. 23 shows the flow of the slack removal processing (step S700). In step S <b> 705, the RR motor control unit 112 drives the RR motor 33 in the reverse direction for a predetermined time by PID control, and starts an operation of winding the paper P at a predetermined transport speed V. In step S710, the control unit 100 acquires the duty (integrated component of the PID control value) of the PWM signal output from the RR motor control unit 112 to the RR motor 33 at a predetermined time period, and the duty reaches a predetermined threshold value. When the time continuously exceeded (cycle × number of times) exceeds a predetermined threshold time, it is determined that the slack has been removed. On the other hand, even if the RR motor 33 is driven for a predetermined time, if the time when the duty continuously exceeds the predetermined threshold does not exceed the threshold time, it is determined that the slack removal has failed. For example, when the roll body RP is attached in the opposite direction, or when a cut sheet is set by mistake, the slack increases when the RR motor 33 is driven in the reverse direction. Thus, it can be determined that the duty does not exceed the predetermined threshold value and the slack removal has failed. It is desirable that the slack removal process is executed before the printing process and the measurement process described above so that the print process and the measurement process can be executed only when the slack removal is successful. Further, when the duty is abnormally large, for example, it may be determined that the paper P is skewed.

2-7. Modification 1
In the above, an example in which the output torque M of the RR motor 33 is adjusted in consideration of the frictional resistance with the platen 55 (suction part 55b) that varies according to the position x of the paper edge on the leading side in the transport direction of the paper P is illustrated. However, other adjustments according to the position x of the paper edge may be performed. For example, the output torque M of the RR motor 33 may be adjusted in consideration of the weight of the conveyed paper P.

FIG. 24 schematically shows the state of the paper P discharged from the discharge unit 59. As shown in the drawing, the paper P is supported on the lower surface BP of the discharge portion 59 until the position x of the paper edge on the leading side in the transport direction of the paper P reaches the position of the lower end of the discharge portion 59. Here, when the angle of the lower surface BP of the discharge portion 59 with respect to the horizontal plane is θ, the weight per unit area of the paper P is ρ, and the gravitational acceleration is g, the force T3 that pulls in the conveyance direction of the paper P by its own weight is large. This can be expressed by the following equation (10).

用紙Ｐの搬送方向先頭側の紙端の位置ｘが排出部５９の下端の位置ｘ₂に達すると、前記の（１０），（１１）式のｘにｘ₂を代入した力Ｔ３，Ｔ４が搬送方向に作用することとなる。さらに、用紙Ｐの搬送方向先頭側の紙端の位置ｘが排出部５９の下端の位置ｘ₃を超えると、超えた分の自重に起因する張力Ｔ５がそのまま用紙Ｐに作用することとなる。位置ｘ₂を超えた分の自重に起因する張力Ｔ５は下記の（１２）式によって表すことができる。

The weight ρ per unit area of the paper P is prepared for each type of paper. If the friction coefficient between the paper P and the lower surface BP is μ ₂ , the frictional resistance force T4 acting between the paper P and the lower surface BP due to the weight of the paper P is expressed by the following equation (11). Can do.

When the position x in the conveying direction leading end of the sheet end of the sheet P reaches the position x ₂ of the lower end of the discharge portion 59, the (10), the force T3, T4 obtained by substituting x ₂ to x in (11) It will act in the transport direction. Furthermore, so that the position x in the conveying direction leading end of the sheet end of the sheet P is more than the position x ₃ of the lower end of the discharge portion 59, the tension T5 due to the amount of its own weight in excess acts directly on the paper P. Tension T5 due to the amount of its own weight exceeds the position x ₂ can be expressed by the following equation (12).

Further, when the sheet edge in the conveying direction leading end of the sheet P is to position x ₃ when reaching the ground, when the paper edge in the conveying direction leading end of the sheet P has exceeded the position x _3, the tension T5 is below (13).

上述した実施形態における前記の（７）式の代わりに前記の（１４）式を用いてＲＲモータ３３の出力トルクＭを算出するようにすれば、用紙Ｐの自重に応じた張力Ｔの調整を行うことができる。 When the edge of the paper reaches the ground, the ground supports the weight that exceeds the position x ₃ , so only the weight for the length (x ₃ −x ₂ ) needs to be considered. As described above, the forces T1 to T5 are applied in the conveyance direction of the paper P including those of the above-described embodiment. The following formula (14) corresponding to the position x can be obtained by balancing the designated tension F and the forces T1 to T5.

If the output torque M of the RR motor 33 is calculated using the equation (14) instead of the equation (7) in the above-described embodiment, the tension T is adjusted according to the weight of the paper P. It can be carried out.

2-8. Modification 2
In the above, the appropriate slip amount is maintained by adjusting the output torque M of the RR motor 33 and setting the tension T acting on the paper P to the designated tension F. However, when the paper end on the rear side of the paper P is detached from the roll body RP, the tension T can no longer be adjusted by the output torque M of the RR motor 33. At the same time, the resistance force T1 due to the rotational resistance of the roll body RP also does not act (T1 = 0). Accordingly, the tension T acting on the paper P is expressed by the following equation (15).

  As indicated by the above equation (15), a tension T unrelated to the output torque M of the RR motor 33 acts on the paper P. Basically, the sheet P is transported in a low tension state because it is released from the rotational resistance T1 of the roll body RP, and the slip amount between the transport driving roller 51a and the sheet P is reduced. . As described above, since the slip amount between the transport driving roller 51a and the paper P can be considered to be proportional to the tension T acting on the paper P, the specified tension F is adjusted to the ideal designated tension F. The drive pattern of the PF motor 53 is set so that the sheet P is transported by the target transport amount ΔLt after a slip amount proportional to is generated. On the other hand, if the specified tension F cannot be adjusted and the tension T of the above equation (15) is applied, a slip amount proportional to the tension T is generated and the sheet P is transported by the target transport amount ΔLt. Thus, it is necessary to set the drive pattern of the PF motor 53. Specifically, a drive pattern in which the hatching area of the drive pattern of the PF motor 53 shown in FIGS. 22A and 22B (a value corresponding to the conveyance amount when there is no slip) has a size corresponding to the tension T may be set. .

  In the state where the paper end on the rear side of the paper P is detached from the roll body RP, the roll body RP does not follow the paper P. Therefore, the encoder counter 34b for the RR motor 33 is driven even though the PF motor 53 is driven. The count number Err is not increased. Therefore, a state in which the paper end on the rear side of the paper P is separated from the roll body RP is detected, and thereafter, the driving pattern of the PF motor 53 on the premise of the tension T of the above formula (15) instead of the designated tension F. Can be changed to

  The printer 10 in the above-described embodiment may be a part of a complex device such as a scanner device or a copy device. Furthermore, in the above-described embodiment, the ink jet printer 10 has been described. However, the printer 10 is not limited to an ink jet printer as long as it can eject fluid. For example, the present invention can be applied to various printers such as a gel jet printer, a toner printer, and a dot impact printer.

1 is a perspective view illustrating a configuration of a printer according to an embodiment of the present invention. It is a figure which shows schematic structure of the printer of FIG. It is a perspective view which shows the structure of the rotation holder holding a roll body. It is a figure which shows an ENC signal. It is a figure which shows the positional relationship of a roll body, a conveyance roller pair, and a print head. It is a block diagram which shows an example of a structure of a control part. 6 is a flowchart of processing executed by a printer. It is a flowchart of a measurement process. It is a figure which shows the example of an output of a rotary sensor. It is a graph which shows the relationship between a conveyance speed and a roll static load. It is a flowchart of an estimation process. It is a graph which shows the 1st correspondence. It is a graph which shows the 1st correspondence. It is a flowchart of a printing process. It is a flowchart of a roll control process (first half). It is a flowchart of a roll control process (forward rotation control process). It is a flowchart of a roll control process (reverse rotation control process). It is a schematic diagram explaining the force which acts on a paper. It is a schematic diagram which shows the relationship between a suction part and a paper. It is a graph which shows the relationship between designated tension, a roll static load, and output torque. It is a figure which shows an example of parameter table PT. It is a timing chart which shows operation of PF motor and RR motor. It is a flowchart of a slack removal process. It is a schematic diagram of the state of the paper discharged from the discharge unit.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Printer, 20 ... Main-body part, 30 ... Roll drive mechanism, 33 ... RR motor (corresponding to 1st motor), 34, 54 ... Rotation detection part, 34b, 54b ... Linear sensor, 40 ... Carriage drive mechanism, 44 ... Print head (corresponding to fluid ejecting head), 50 ... paper transport mechanism, 51 ... pair of transport rollers, 53 ... PF motor (corresponding to second motor), 100 ... control unit, 110 ... main control unit, 111 ... PF motor control Part, 112... RR motor control part.

Claims (7)

A first motor for applying a driving force for rotating a roll body around which the printing medium is wound; a second motor for supplying a driving force for driving a conveyance driving roller for conveying the printing medium; and ink for the printing medium. A printing method in a printing apparatus provided with a print head for jetting,
A printing method, wherein the first motor is driven in accordance with a leading end position of the print medium. The printing apparatus includes a suction unit that holds the print medium with respect to the print head by sucking the print medium.
2. The printing method according to claim 1, wherein a tension acting on the print medium is adjusted by driving the first motor in accordance with a position of a leading end of the print medium with respect to the suction portion.   3. The suction area of the print medium sucked by the suction unit is specified based on the position of the leading end of the print medium, and the first motor is driven according to the suction area. The printing method as described in.   4. The printing according to claim 1, wherein the printing apparatus drives the first motor according to a length of the printing medium unwound from the roll body. 5. Method.   The printing method according to claim 4, wherein the printing apparatus drives the first motor in accordance with the weight of the print medium unwound from the roll body.   The drive amount of the second motor for transporting the print medium by a predetermined amount is changed before and after the rear end of the print medium is detached from the roll body. 5. The printing method according to any one of 4 above. A first motor for applying a driving force for rotating a roll body around which the printing medium is wound; a second motor for supplying a driving force for driving a conveyance driving roller for conveying the printing medium; and ink for the printing medium. A printing device equipped with a print head for jetting,
A printing apparatus comprising: control means for driving the first motor in accordance with a leading end position of the print medium.

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