JP2011046518A - Printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printer for surely eliminating a skew. <P>SOLUTION: The printer includes a first motor for imparting a drive force for rotating a roll body wound with a medium, a carrier roller arranged at the downstream side in the supply direction of the medium more than the roll body, a second motor for imparting the drive force for rotating the carrier roller, a control part for controlling the first motor and the second motor so as to carry the medium in the opposite direction of the supply direction for winding the medium on the roll body, that is, the control part for controlling tension generated in the medium between the roll body and the carrier roller based on a duty value of the PWM control of the first motor and a limiting duty value with respect to at least an integral output in the PID control of the first motor. The control part adds and subtracts a predetermined duty value to and from the duty value in the PWM control in acceleration/deceleration when driving the first motor, and adds and subtracts the predetermined duty value to and from the limiting duty value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a printing apparatus.

For example, among ink jet printers, there is a type that uses a large paper having a paper size of A2 or larger. In such large-format inkjet printers, so-called roll paper is often used in addition to cut paper. In the following description, a so-called roll paper around which paper is wound is referred to as a roll body, and a portion pulled out from the roll body is referred to as paper.
At present, the paper is drawn 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 shown in Patent Document 1. Also, 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

When a large roll body is set in the printer as described above, a state (so-called skew) in which the longitudinal direction of the sheet is inclined with respect to the original drawing direction (supply direction) is likely to occur. For this reason, it is necessary to eliminate the skew before starting printing. Therefore, a printing apparatus provided with a roll motor that rotationally drives the roll body, drives the PF motor and the roll motor at the same time (so that the paper is wound on the roll body), and eliminates skew by the simultaneous drive. Is being considered.
However, in the above-described printing apparatus, when the target tension is reached during the acceleration / deceleration of the drive of the roll motor, there is a possibility that the skew cannot be eliminated.
Therefore, an object of the present invention is to reliably eliminate skew.

  The main invention for achieving the above object is to provide a first motor for applying a driving force for rotating a roll body around which a medium is wound, and a conveyance provided downstream of the roll body in the medium supply direction. A roller, a second motor for applying a driving force for rotating the transport roller, and the first motor so that the medium is transported in a direction opposite to the supply direction to wind the medium around the roll body. A control unit for controlling the second motor, based on a duty value of PWM control of the first motor, and a limiting duty value for at least an integral output in PID control of the first motor; A control unit that controls a tension generated in the medium between the conveying roller and the control unit, and the control unit accelerates or decelerates when driving the first motor. Wherein with the addition or subtraction of predetermined duty value in the duty value of the PWM control, a printing apparatus, characterized by subtracting the predetermined duty value to the limit duty value.

  Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

FIG. 2 is a diagram illustrating a configuration example of an appearance of a printer. It is a figure which shows the relationship between the drive system using the DC motor in a printer, and a control system. It is a figure which shows the structural example of the external appearance of a rotation holder and a roll motor. FIG. 4A is a timing chart of the waveform of the output signal when the roll motor is rotating forward. FIG. 4B is a timing chart of the waveform of the output signal when the roll motor is rotating in reverse. It is a figure which shows the positional relationship of a roll body, a conveyance roller pair, and a printing head. It is a block diagram which shows the functional structural example of a control part. It is a block diagram which shows the structural example of a PID calculating part. It is a figure which shows an example of a speed table. It is a figure which shows the relationship between the Duty value and speed | velocity | rate in measurement operation | movement. It is a figure which shows the operation | movement flow in synchro drive control. FIG. 6 is a perspective view illustrating a state where a skew is generated in a sheet. It is a figure which shows the table used by 2nd Embodiment.

  At least the following matters will become clear from the description of the present specification and the accompanying drawings.

A first motor for applying a driving force for rotating a roll body around which the medium is wound, a conveying roller provided on the downstream side in the medium supply direction from the roll body, and a driving force for rotating the conveying roller And a control unit that controls the first motor and the second motor so that the medium is conveyed in a direction opposite to the supply direction to wind the medium around the roll body. The tension generated in the medium between the roll body and the transport roller based on the duty value of PWM control of the first motor and the limit duty value for at least the integral output in the PID control of the first motor A control unit for controlling the duty ratio in the PWM control during acceleration / deceleration when driving the first motor. With the addition or subtraction of predetermined duty value, the printing apparatus characterized by adding or subtracting the predetermined duty value to the limit duty value becomes apparent.
According to such a printing apparatus, the control at the time of acceleration / deceleration of the first motor can be accurately performed, and the skew can be surely eliminated.

  The limit duty value may be a value for a total value of a proportional output of the PID control for the first motor, the integral output, and the derivative output.

In the printing apparatus, the predetermined duty value may be determined in advance according to acceleration and deceleration when the first motor is driven.
According to such a printing apparatus, the limit duty value at the time of acceleration / deceleration can be easily calculated.

In this printing apparatus, the printing apparatus includes a storage unit that stores a table indicating a correspondence relationship between the speed of the roll body after the driving of the first motor is started and the predetermined duty value. The duty value may be determined based on the table.
According to such a printing apparatus, the limit duty value at the time of acceleration / deceleration can be accurately calculated.

In this printing apparatus, the predetermined duty value may be calculated by performing an operation based on a torque when driving the roll body in the control unit.
According to such a printing apparatus, the limit duty value during acceleration / deceleration can be calculated more accurately.

=== First Embodiment ===
Hereinafter, the printer 10 as a printing apparatus and the drive control method will be described. Note that the printer 10 of the present embodiment is a printer for printing large-sized paper (for example, a size of JIS standard A2 or larger). The printer in this embodiment is an ink jet printer. However, the ink jet printer may be an apparatus that employs any ejection method as long as the apparatus can print by ejecting 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 described as a supply side (rear end side), and the side on which the paper P is discharged will be described as a paper discharge side (front side).

<About printer configuration>
FIG. 1 is a diagram illustrating a configuration example of an appearance of a printer 10 according to the present embodiment. FIG. 2 is a diagram illustrating a relationship between a drive system using a DC motor and a control system in the printer 10 of FIG. FIG. 3 is a view showing a configuration example of the outer appearance of the rotary holder 31 and the roll motor 33.
In 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 unit 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.

Further, the roll drive mechanism 30 for rotating the roll body RP includes a rotation holder 31, a gear wheel train 32, a roll motor 33, and a rotation detection unit 34, as shown in FIGS. ing.
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 roll motor 33 applies a driving force (rotational force) via the gear wheel train 32 to the rotation holder 31 a located on one end side of the pair of rotation holders 31. That is, the roll motor 33 corresponds to a first motor that provides a driving force for rotating the roll body.

  The rotation detector 34 uses a rotary encoder in this embodiment. Therefore, the rotation detection unit 34 includes a disk 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.

  FIG. 4A is a timing chart of the waveform of the output signal when the roll motor 33 is rotating forward. FIG. 4B is a timing chart of the waveform of the output signal when the roll motor 33 is rotating in reverse. In the present 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 FIGS. 4A and 4B are input to the control unit 100 by the output from the rotary sensor 34b. Is done. Therefore, whether the roll motor 33 is in the forward rotation state or the reverse rotation state can be detected by the advance / delay of the phase.

  The carriage drive mechanism 40 includes a carriage 41 that is a part of the components of the ink supply / ejection mechanism, a carriage shaft 42, and other carriage motors and belts (not shown).

  The carriage 41 is provided with an ink tank 43 for storing ink of each color, and the ink tank 43 is fixedly provided on the front side of the main body 20 via a tube (not shown). Ink can be supplied from a cartridge (not shown). Further, as shown in FIG. 2, a print head 44 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 the operation of this 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. The 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.

  The sheet transport mechanism 50 includes a transport roller pair 51, a gear train 52, a PF motor 53, and a rotation detection unit 54, as shown in FIGS. 5 is a diagram illustrating the positional relationship between the roll body RP, the transport roller pair 51, and the print head 44.

The transport roller pair 51 includes a transport roller 51a and a transport driven roller 51b, and a sheet P (roll paper) drawn from the roll body RP can be sandwiched therebetween.
The PF motor 53 applies a driving force (rotational force) to the transport roller 51a via the gear wheel train 52. That is, the PF motor 53 corresponds to a second motor that provides a driving force for rotating the transport roller 51a.

The rotation detection unit 54 uses a rotary encoder in the present embodiment, and includes a disk-like scale 54a and a rotary sensor 54b, similar to the rotation detection unit 34 described above, as shown in FIGS. 4A and 4B. A pulse signal can be output.
Further, a platen 55 is provided on the downstream side (paper discharge side) from the transport roller pair 51, and the paper P is guided on the platen 55. The print head 44 is disposed on the platen 55 so as to face the platen 55. A suction hole 55 a is formed in the platen 55. 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 other various sensors such as a paper width detection sensor that detects the width of the paper P.

<About the control unit>
FIG. 6 is a block diagram illustrating a functional configuration example of the control unit 100. The control unit 100 is a part that performs various controls. The control unit 100 receives output signals such as rotary sensors 34b and 54b, a linear sensor (not shown), a paper width detection sensor (not shown), a gap detection sensor (not shown), and a power switch for turning on / off the printer 10. Entered. As shown in FIG. 2, the control unit 100 includes a CPU 101, a ROM 102, a RAM 103, a PROM 104, an ASIC 105, a motor driver 106, and the like, 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 as shown in FIG. 6 is performed by cooperation of these hardware and software and / or data stored in the ROM 102 or PROM 104, or by adding a circuit or a component for performing specific processing. The unit 110, the PF motor control unit 111, and the roll motor control unit 112 are realized.

  Of these, the main control unit 110 provides both the roll motor control unit 120 and the PF motor control unit 130 to realize synchronous drive (synchronous drive) of the roll motor 33 and the PF motor 53 as will be described later. Give a command to it. The roll motor control unit 120 and the PF motor control unit 130 have PID calculation units 140a and 140b, respectively (note that the two PID calculation units 140a and 140b are basically the same, When it is not necessary to distinguish between the two in the description, they are simply expressed as PID calculation unit 140). Further, the roll motor control unit 120 is provided with an output correction unit 121 in addition to the PID calculation unit 140a described above.

  FIG. 7 is a block diagram illustrating a configuration example of the PID calculation unit 140. The PID calculation units 140a and 140b will be described with reference to FIG. In addition, the relationship between the PID calculation unit 140a and the output correction unit 121 in the roll motor control unit 120 will be described with reference to FIG. Note that the portion surrounded by the broken line in FIG. 7 (which forms part of the output correction unit 121) is provided only in the roll motor control unit 120 as described above.

  As shown in FIG. 7, the PID calculation unit 140 includes a position calculation unit 141, a speed calculation unit 142, a first subtraction unit 143, a target speed generation unit 144, a second subtraction unit 145, and a proportional element 146. , An integration element 147, a differentiation element 148, an integration correction unit 149, an addition unit 150, a final output correction unit 151, a PWM signal output unit 152, and a timer 153.

  Among these components, the integral correction unit 149 and the final output correction unit 151 are components corresponding to some elements of the output correction unit 121 described above, and are provided only in the roll motor control unit 120. Further, it is sufficient that either one of the integral correction unit 149 and the final output correction unit 151 is selectively provided. That is, in the block diagram of FIG. 6, when the integral correction unit 149 is provided, the final output correction unit 151 is not necessary, and when the final output correction unit 151 is provided, the integration correction unit 149 is not necessary. However, a configuration including both the integral correction unit 149 and the final output correction unit 151 may be employed.

  The position calculation unit 141 calculates the feed amount of the paper P by counting the edges of the rectangular wave output signals (see FIGS. 4A and 4B) input from the rotary sensors 34b and 54b. Further, the speed calculator 142 counts the edges of the rectangular wave output signals input from the rotary sensors 34b and 54b, and also receives a signal related to the time (cycle) measured by the timer 153. Then, the feeding speed of the paper P is calculated based on the counted edge and time (cycle).

  The first subtracting unit 143 is based on the information on the feed amount (current position) output from the position calculating unit 141 and the information on the target position (target stop position) output from the memory such as the ROM 102 or the PROM 104. The position deviation is calculated by subtracting the current position from (target stop position). Information on the positional deviation output from the first subtraction unit 143 is input to the target speed generation unit 144. Then, the target speed generation unit 144 outputs information regarding the target speed according to the position deviation. Note that the information regarding the target speed relates to a speed table as shown in FIG. As shown in FIG. 8, there are two speed tables, a speed table roll for the roll motor 33 and a speed table pf for the PF motor 53.

The second subtracting unit 145 subtracts the feed speed (current speed) of the current motor (roll motor 33 or PF motor 53) from the target speed to calculate the speed deviation ΔV, and the proportional element 146, the integral element 147, and the derivative Each is output to element 148. The proportional element 146, the integral element 147, and the derivative element 148 calculate the following proportional control value QP, integral control value QI, and differential control value QD based on the input speed deviation ΔV.
QP (j) = ΔV (j) × Kp (Expression 1)
QI (j) = QI (j−1) + ΔV (j) × Ki (Expression 2)
QD (j) = {ΔV (j) −ΔV (j−1)} × Kd (Formula 3)
Here, j is time, Kp is a proportional gain, Ki is an integral gain, and Kd is a differential gain.

In the present embodiment, the integral correction unit 149 compares the integral control value QI output from the integral element 147 with the threshold value Dx. Details of the threshold value Dx will be described later. If the result of this comparison is | QI | <Dx, the output from the integration correction unit 149 to the addition unit 150 is set to QI which is an integration control value. If the result of the above comparison is | QI | ≧ Dx, the output from the integral correction unit 149 to the addition unit 150 is set as the threshold value Dx. Here, | QI | is the absolute value of QI.
When the integration correction unit 149 is not provided, the output (integration control value QI) from the integration element 147 is input to the addition unit 150 as it is.

  When the integration correction unit 149 is not provided, the addition unit 150 adds the control values output from the proportional element 146, the integration element 147, and the differentiation element 148, and sums the control values obtained by the addition. (Total value; Qpid) is output to the PWM signal output unit 152 (or the final output correction unit 151). Further, when the integration correction unit 149 is provided, the addition unit 150 adds each control value output from the proportional element 146 and the differentiation element 148 and the control value output from the integration correction unit 149. Then, the sum (Qpid) of the control values obtained by the addition is output to the PWM signal output unit 152 (or the final output correction unit 151).

  The final output correction unit 151 compares the control value Qpid output from the addition unit 150 with the threshold value Dx. If the result of this comparison is | Qpid | <Dx, the output from the adder 150 to the PWM signal output unit 152 is set as the control value Qpid. Further, if the result of the above comparison is | Qpid | ≧ Dx, the output from the adding unit 150 to the PWM signal output unit 152 is set as the threshold value Dx. Note that | Qpid | is the absolute value of Qpid.

  When the final output correction unit 151 is not provided in the PWM signal output unit 152, the control value Qpid output from the addition unit 150 is input. On the other hand, when the final output correction unit 151 is provided, the control value that has passed through the final output correction unit 151 is input. The PWM signal output unit 152 outputs a PWM signal having a duty value obtained by converting the supplied control value.

  The timer 153 receives a signal from a clock (not shown). When a predetermined PID calculation cycle such as 100 μsec arrives, a timer signal is output to the speed calculation unit 142 for each PID calculation cycle.

  The motor driver 106 controls and drives the roll motor 33 or the PF motor 53 by PWM control based on the PWM signal output from the PWM signal output unit 152.

<About the threshold value Dx>
As described above, the output correction unit 121 operates as the integration correction unit 149 and the final output correction unit 151 as described above, and performs calculation for obtaining the threshold value Dx as described below. In the present embodiment, the threshold value Dx is used to apply a tension F (for example, a tension of a predetermined magnitude that does not break the paper P even if applied to the paper P) to the paper P as shown in (Expression 4). Duty (f), which is the required duty value, Duty (ro), which is the duty value required to drive the roll motor 33 at a certain speed Vn, and Duty (ad), which is the duty value required for acceleration and deceleration It is obtained by adding.

  Dx = Duty (f) + Duty (ro) + Duty (ad) (Formula 4)

≪About Duty (ro) ≫
In order to obtain a duty value required to drive the roll motor 33 at a certain speed Vn, a measurement operation is performed. In this measurement operation, as shown in FIG. 9, the roll body RP is rotationally driven in the forward rotation direction at the low speed VL and the high speed VH. Then, a measurement value ave TiL required to drive the roll motor 33 at the low speed VL and a measurement value ave TiH required to drive the roll motor 33 at the high speed VH are calculated. The measurement value ave TiL and the measurement value ave TiH are average values of control values output from the integration element 147 of the PID calculation unit 140 when PID control is performed at each speed.

When the measurement value ave TiL and the measurement value ave TiH are obtained, the relationship of the linear expression as shown in FIG. 9 is established, so that (Expression 5) is established and the coefficients a and b are obtained by the measurement operation. It is obtained using the measurement value ave TiL and the measurement value ave TiH ((Expression 6), (Expression 7)).
Duty (ro) = aVn + b (Formula 5)
a = (ave TiH−ave TiL) / (VH−VL) (Formula 6)
b = ave TiH− (ave TiH−ave TiL) × VL / (VH−VL) (Expression 7)

≪About Duty (f) ≫
Consider a case where the roll motor 33 is driven at a certain speed Vn and a tension F is applied to the paper P at that time. At this time, the current value Io required to drive the roll motor 33 is set such that the radius of the roll body RP is r, the torque required to drive the roll motor 33 is Tro, and the motor constant of the roll motor 33 is Kt. Then, it is obtained by the following formula.
Io = (F × r + Tro) / Kt (Equation 8)

Here, the threshold value Dx that is the duty value of the roll motor 33, the power supply voltage E, the internal resistance R of the roll motor 33, and the reverse of the roll motor 33 when the paper P is conveyed at the speed Vn in a state where the tension F is applied. From the electromotive force constant Ke, the following equation is established.
Io = (E * Dx / Duty (max) -KeVn) / R (Formula 9)
Note that Duty (max) is the maximum value of the Duty value. Further, the threshold value Dx here is a value at a constant speed (speed Vn), and therefore it is assumed that Duty (ad) in (Expression 4) is not included. That is,
Dx = Duty (f) + Duty (ro) (Formula 4) ′
It is.

Further, assuming that the torque required to drive the roll motor 33 at a certain speed Vn is Tro, and the duty value at that time is Duty (ro), the torque Tro is expressed as follows by the current value I1 and the motor. It is obtained from the product of constants.
Tro = Kt * I1 = Kt * (E * Duty (ro) / Duty (max) -Ke * Vn) / R
... (Formula 10)

(Equation 8) and (Equation 9) are the same. Further, when (Equation 10) is substituted into Tro of (Equation 8) and both sides are arranged, the result is as follows. ●
(F × r / Kt) + (E × Duty (ro) / Duty (max) −Ke × Vn) / R
= (E * Dx / Duty (max) -Ke * Vn) / R
∴Dx = F × r × Duty (max) / (Kt × E) + Duty (ro) (Equation 11)
Therefore, Duty (f) in (Equation 4) ′ is
Duty (f) = F × r × Duty (max) / (Kt × E) (Equation 12)

≪About Duty (ad) ≫
A strong force is required to control the rotation of the roll body RP during acceleration and deceleration. Therefore, in the present embodiment, Duty (ad) is added to or subtracted from the duty value of PWM control and the threshold value Dx according to each PID calculation period during acceleration and deceleration.
For example, during acceleration, Duty_acc is added to the Duty value and threshold value Dx for each PID calculation cycle, and during deceleration, Duty_dec is subtracted from the Duty value and threshold value Dx. Note that Duty_acc is the value of Duty (ad) during acceleration, and Duty_dec is the value of Duty (ad) during deceleration.
Therefore, from (Equation 5), (Equation 12), and the above Duty (ad), the threshold value Dx is expressed by the following equation.
(Acceleration)
Dx = F * r * Duty (max) / (Kt * E) + aVn + b + Duty_acc (Equation 13)
(At constant speed)
Dx = F * r * Duty (max) / (Kt * E) + aVn + b (Formula 14)
(During deceleration)
Dx = F * r * Duty (max) / (Kt * E) + aVn + b-Duty_dec (Formula 15)

<Control method of roll motor 33 and PF motor 53>
A method of synchro drive control (skew removal) of the roll motor 33 and the PF motor in the printer 10 having the above configuration will be described.

FIG. 10 is a diagram illustrating an example of an operation flow in the synchro drive control.
First, prior to driving for carrying out skew removal, a measurement operation is executed (S01). In the measurement operation, the roll motor 33 is driven at two speeds VL and VH on the low speed side and the high speed side on the basis of a command from the main control unit 110, and thereby the coefficients a and b in the above-described (Equation 4). Is required.

Subsequently, the feed amount by driving the roll motor 33 is calculated (S02). The calculation of the feed amount is based on the pulse number count in the rotary sensors 34b and 54b. The feed amount Lroll (the count number of the ENC signal) is counted when the transport roller 51a makes one round. The count number of the signal is Cpf, the count number of the ENC signal counted when the roll body RP makes one round is Croll, the diameter of the transport roller is Dpf, the diameter of the roll body RP is Droll, and it corresponds to the feed amount of the transport roller. If the count number of the ENC signal is Lpf, it can be obtained by the following equation.
Lroll = (Dpf × π × Lpf / Cpf) / (Droll × π) × Croll (Expression 16)

  Here, since the diameter Droll of the roll body RP changes as the paper P is pulled out, it is necessary to obtain the diameter Droll. The diameter Droll is calculated by counting the ENC signals output from the rotary sensors 34b and 54b while energizing only one of the roll motor 33 and the PF motor 53 and not energizing the other. Some are calculated based on the number relationship. Further, from the relationship between the detected value from the direct detection (not shown) existing between the roll body RP and the transport roller pair 51 and the count number of the ENC signal output from one of the rotary sensors 34b and 54b. The diameter Droll may be calculated.

  When the feed amount is calculated in step S02, driving of the roll motor 33 and the PF motor 53 is started based on a command from the main control unit 110 (S03). At this time, the roll motor 33 and the PF motor 53 are driven according to a drive table as shown in FIG. In the drive table shown in FIG. 8, the feeding speed of the paper P driven by the roll motor 33 is set to be larger than the feeding speed driven by the PF motor 53 to prevent the paper P from slackening. .

  Further, when the roll motor 33 and the PF motor 53 are driven, if the paper P is loosened between the roll body RP and the transport roller pair 51, the skew generated in the paper P cannot be eliminated. Therefore, whether the roll motor 33 and the PF motor 53 are driven simultaneously, or the roll motor 33 is driven first, and then the PF motor 53 is driven when the roll motor 33 is rotationally driven by a predetermined amount. Either driving method is employed. When the roll motor 33 is driven, the threshold value Dx is calculated as described above according to acceleration, constant speed, and deceleration (S04).

  Further, when driving the roll motor 33 and the PF motor 53 in step S03, the roll motor 33 and the PF motor 53 are driven while controlling the tension F acting on the paper P (S05). In the control of the tension F, the magnitude relationship with the threshold value Dx is compared in either the integral correction unit 149 or the final output correction unit 151 as described above. That is, when using the integral correction unit 149, the absolute value of the integral control value QI output from the integral element 147 is compared with the threshold value Dx, and if the comparison result is | QI | <Dx, the integral correction unit 149 To the adder 150 is defined as an integral control value QI. If the result of the above comparison is | QI | ≧ Dx, the output from the integral correction unit 149 to the addition unit 150 is set as the threshold value Dx.

  When the final output correcting unit 151 is used, the control value Qpid output from the adding unit 150 is compared with the threshold value Dx, and if the result of this comparison is | Qpid | <Dx, the PWM signal is output from the adding unit 150. The output to the output unit 152 is set as a control value Qpid. Further, if the result of the above comparison is | Qpid | ≧ Dx, the output from the adding unit 150 to the PWM signal output unit 152 is set as the threshold value Dx. The tension control for preventing the paper P from being broken as described above (control to prevent the integrated output or the final output from exceeding the threshold value Dx) is performed in step S05.

  When the drive with tension control as described above proceeds, the paper P is wound around the roll body RP in a state where the tension F is applied. When the paper P is wound around the roll body RP while applying tension to the paper P in this way, the skew generated in the paper P can be eliminated.

  For example, when the paper P is skewed, as shown in FIG. 11, although there is no slack at one end in the width direction of the paper P, the slack amount of the paper P gradually increases toward the other end. A state of increasing occurs. Therefore, when the paper P is wound around the roll body RP while applying tension as in S05, until the slack portion of the paper P is loosened (until the predetermined tension is reached). The sheet P existing at the downstream side is not sent toward the upstream side. Therefore, if the paper P is wound around the roll body RP while applying tension, the skew generated in the paper P can be eliminated.

  When performing the process of step S05, the main control unit 110 determines whether or not a predetermined feed amount has been sent at every predetermined timing (S06). The feed amount here is the feed amount Lpf and the feed amount Lroll in step S01 described above. The determination in step S05 may be made based on only one of the feed amount Lpf and the feed amount Lroll.

  Further, when it is determined in step S05 described above that a predetermined feed amount has been sent (in the case of Yes), the driving of the roll motor 33 and the PF motor 53 is stopped (S07). At this time, according to the drive table shown in FIG. 8, the PF motor 53 is stopped first, and then the roll motor 33 is stopped. However, the PF motor 53 and the roll motor 33 may be stopped simultaneously.

  If it is determined in step S06 that the predetermined feed amount is not sent (No), the process returns to step S03 and the process is continued.

  As described above, the output correction unit 121 operates, whereby the skew of the paper P is eliminated.

  According to the printer 10 configured as described above, the tension applied to the paper P is controlled to be equal to or less than the tension F. Accordingly, it is possible to prevent a large tension from acting on the paper P, and it is possible to prevent problems such as the paper P breaking.

<Comparative example>
If the duty value (Duty (ad)) during acceleration / deceleration is not considered in (Expression 4), the threshold value Dx can be calculated from (Expression 4) ′ by Dx = Duty (f) + Duty (ro)
= F * r * Duty (max) / (Kt * E) + aVn + b
It becomes. This is a duty value (that is, a constant value) when the paper P is conveyed at the speed Vn in a state where a certain tension F is applied.

  During acceleration, a strong force is required to rotate the roll body RP. That is, it is necessary to increase the duty value of PWM control for driving the roll motor 33. That is, during acceleration, control is performed so that the duty value of PWM control is increased. Conversely, during deceleration, control is performed so that the duty value of PWM control becomes smaller.

  By the way, when the roll body RP having a large diameter (heavy) is driven by the small roll motor 33, it is necessary to make acceleration as slow as possible and lengthen the acceleration time. However, if the acceleration time becomes longer in this way, the Duty value may reach the threshold value Dx at the acceleration stage. Then, there is a risk that the skew elimination processing may be completed without obtaining the original (target) tension. For this reason, there is a possibility that the skew cannot be completely removed.

In contrast, in this embodiment, a predetermined duty value is added to or subtracted from the duty value in PWM control during acceleration / deceleration when driving the roll motor 33, and the duty value is also added to or subtracted from the threshold value Dx. As a result, it is possible to accurately perform the skew elimination process, and it is possible to reliably eliminate the skew.
Further, in the present embodiment, since a certain duty value is added or subtracted at the time of acceleration / deceleration, the threshold value Dx can be easily calculated.

=== Second Embodiment ===
In the above-described embodiment, a fixed duty value is added to or subtracted from the duty value of PWM control and the threshold value Dx during acceleration or deceleration. In the second embodiment, a table indicating the correspondence between the speed table after the start of the roll motor 33 and the duty value during acceleration / deceleration is prepared in advance, and the table is displayed during acceleration / deceleration. By referencing, addition and subtraction of the Duty value is performed.

FIG. 12 is a diagram illustrating an example of a table used in the second embodiment.
The horizontal axis in the figure indicates the transport distance of the paper P (that is, the amount of rotation of the roll body RP after the motor starts driving). Further, the left side of the vertical axis indicates the speed, and the right side of the vertical axis indicates the value of Duty.
Also, the dotted line in the figure indicates the speed table roll, and the solid line indicates the duty value (Duty_acc and Duty_dic) required when the roll motor 33 is accelerated and decelerated. PID control is performed based on such a speed table, and a Duty value is calculated for each PID calculation cycle.

At the time of acceleration (at the time of speed increase), as described above, a strong force is required to rotate the roll body RP, so that the duty value (Duty_acc) necessary for acceleration is gradually increased.
At constant speed, the Duty value is constant (no change).
Also, when decelerating (when the speed is decreasing), a force opposite to that during acceleration is required. In other words, the duty value required at the time of deceleration becomes a duty value (-Duty_dic) having the opposite sign to that at the time of acceleration. As the speed decreases, the duty value required for deceleration also decreases (the absolute value of the duty value decreases).

The table shown in FIG. 12 is stored in a memory (corresponding to a storage unit) such as the ROM 102 or the PROM 104 of the control unit 100, for example.
The output correction unit 121 determines Duty (ad) of (Equation 4) with reference to the table of FIG. 12 for each PID calculation period when the roll motor 33 is driven and decelerated. That is, the duty value for PWM control and the duty value to be added to or subtracted from the threshold value Dx are determined.
Since other processes are the same as those in the first embodiment, description thereof will be omitted.

  In the second embodiment, since the duty value to be added to or subtracted from the threshold value Dx during acceleration / deceleration is determined based on a table as shown in the figure, the threshold value Dx can be accurately calculated. Therefore, the queue can be reliably eliminated.

=== Third Embodiment ===
The third embodiment is different from the above-described embodiment in that a duty value (Duty (ad)) necessary for acceleration / deceleration is obtained by calculation.
The output correction unit 121 according to the third embodiment calculates a duty value necessary for acceleration / deceleration by the following calculation. In the following description, the torque is T, the inertia is J, the current speed is v, the speed at the previous calculation is v ′, the calculation interval is Δt, the torque constant is Kt, the current is I, the power supply voltage is E, The motor resistance is R, the maximum PWM duty is Duty (max), the PWM duty is Duty, and the back electromotive force constant is Ke.

となる。
また、トルクＴはトルク定数Ｋｔとモーターに流れる電流Ｉの積で表されるので、

となる。上記の２つの式からDutyは、

となる。よって、この（式１９）を使うことにより、加減速の時のDuty（ad）を求めることができる。但し、イナーシャＪは、ロール体ＲＰの大きさ（重さ）によって変わってくる。そこで、イナーシャＪは、メジャメント値に比例すると仮定し、
Ｊ＝Ａ×ａｖｅＴｉL＋Ｂ
とする。なお、Ａ、Ｂは定数である。
このようにして、出力補正部１２１は、加速時あるいは減速時にＰＩＤ演算周期ごとにDuty（ad）を求め、そのDuty値を（式４）に入れて閾値Ｄｘを求める。
なお、その他の処理については、前述の実施形態と同じであるので説明を省略する。 Torque T is the product of inertia J and acceleration

It becomes.
The torque T is expressed by the product of the torque constant Kt and the current I flowing through the motor.

It becomes. From the above two equations, Duty is

It becomes. Therefore, by using (Equation 19), Duty (ad) at the time of acceleration / deceleration can be obtained. However, the inertia J varies depending on the size (weight) of the roll body RP. Therefore, assuming that inertia J is proportional to the measurement value,
J = A × aveTiL + B
And A and B are constants.
In this way, the output correction unit 121 obtains Duty (ad) for each PID calculation period during acceleration or deceleration, and obtains the threshold value Dx by putting the Duty value in (Equation 4).
Other processes are the same as those in the above-described embodiment, and thus description thereof is omitted.

  In the third embodiment, since Duty (ad) required at the time of acceleration / deceleration is calculated based on the motor driving torque, the threshold value Dx at the time of acceleration / deceleration can be calculated more accurately.

=== Other Embodiments ===
Although a printer or the like as one embodiment has been described, the above embodiment is for facilitating the understanding of the present invention, and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof. In particular, the embodiments described below are also included in the present invention.

  In the above-described embodiment, the case where the motor control device is provided in the printer 10 has been described. However, the motor control device is not limited to being provided in the printer 10, and may be applied to a fax machine using a roll body (roll paper). In the embodiment described above, the paper P is a roll paper, but other than the paper P, a film-like member, a resin sheet, an aluminum foil, or the like may be used.

  The control unit 100 is not limited to that of the above-described embodiment, and may be configured to control the roll motor 33 and the PF motor 53 by using only the ASIC 105, for example. The control unit 100 may be configured by combining a one-chip microcomputer or the like in which a device is incorporated.

  Furthermore, in the above-described embodiment, the PID control in the control unit 100 is performed with respect to the speed, but PID control regarding the position may be performed. Further, the control of the roll motor 33 and the PF motor 53 is not limited to PID control, and the present embodiment may be applied to PI control, for example.

  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 a fluid. For example, the present embodiment can be applied to various printers such as a gel jet printer, a toner printer, and a dot impact printer.

10 printer, 20 main body, 30 roll drive mechanism,
33 roll motor, 34, 54 rotation detector,
34b, 54b linear sensor, 40 carriage drive mechanism,
44 print head, 50 paper transport mechanism,
51 transport roller pair, 51a transport roller,
51b Conveyor driven roller, 53 PF motor,
100 control unit, 110 main control unit, 111 PF motor control unit,
120 roll motor control unit, 121 output correction unit,
130 PF motor control unit, 140a, 140b PID calculation unit,
149 integral correction unit, 151 final output correction unit, 152 PWM signal output unit,
RP roll body, P paper

Claims (5)

A first motor for providing a driving force for rotating the roll body around which the medium is wound;
A transport roller provided downstream of the roll body in the supply direction of the medium;
A second motor for providing a driving force for rotating the transport roller;
A controller for controlling the first motor and the second motor so that the medium is conveyed in a direction opposite to the supply direction in order to wind the medium around the roll body; A control unit for controlling tension generated in the medium between the roll body and the transport roller based on a duty value of PWM control and a limiting duty value for at least an integral output in PID control of the first motor;
With
The control unit adds / subtracts a predetermined duty value to / from a duty value in the PWM control during acceleration / deceleration when driving the first motor, and adds / subtracts the predetermined duty value to / from the limit duty value. Printing device to do. The printing apparatus according to claim 1,
The printing apparatus according to claim 1, wherein the limit duty value is a value with respect to a total value of a proportional output of the PID control for the first motor, the integral output, and the derivative output. The printing apparatus according to claim 1 or 2,
The printing apparatus according to claim 1, wherein the predetermined duty value is predetermined in accordance with acceleration and deceleration when the first motor is driven. The printing apparatus according to claim 1 or 2,
A storage unit that stores a table indicating a correspondence relationship between the speed of the roll body after the first motor starts to be driven and the predetermined duty value;
The printing apparatus according to claim 1, wherein the predetermined duty value is determined based on the table. The printing apparatus according to claim 1 or 2,
The printing apparatus according to claim 1, wherein the predetermined duty value is calculated by performing a calculation based on a torque when driving the roll body in the control unit.

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