JP7456202B2 - Sheet conveyance device and image forming system - Google Patents

Description

This disclosure relates to a sheet conveying device and an image forming system.

2. Description of the Related Art Conventionally, there has been known a recording apparatus that uses a conveyance roller to pull out a sheet in the direction of a recording head from a sheet roll around which the sheet is wound, and records an image on the pulled out sheet (for example, see Patent Document 1).

In this recording apparatus, the diameter of the sheet roll is measured by an optical sensor in order to synchronize the speed of the sheet on the outer periphery of the sheet roll with the speed of the sheet on the conveyance roller. Based on the measured diameter of the sheet roll, a target value of the rotation speed of the sheet roll for synchronization is calculated. Furthermore, in order to rotate the sheet roll in accordance with the acceleration of the transport roller, the amount of operation for the motor that rotationally drives the sheet roll is corrected based on the rotational acceleration of the transport roller.

Japanese Patent Application Publication No. 2013-91219

In a sheet conveyance device that uses sheet rolls, the weight of the sheet roll changes depending on sheet consumption. Depending on this change in weight, the amount of operation for the motor appropriate for controlling the accelerated motion of the sheet roll to the target motion changes.

In the prior art, since the motor is not controlled in consideration of such changes in the weight of the sheet roll, it has been difficult to appropriately control the sheet conveyance with respect to sheet conveyance that involves an acceleration process.

Therefore, according to one aspect of the present disclosure, it is desirable to provide a sheet conveyance device that can appropriately perform sheet conveyance control that involves an acceleration process in an environment where the weight of a sheet roll changes as the sheet is consumed.

A sheet conveyance device according to one aspect of the present disclosure includes a holder, a conveyance roller, a first motor, a second motor, a tension estimator, a measuring device, and a controller. The holder holds a sheet roll around which a sheet is wound.

The conveyance roller rotates and conveys the sheet pulled out from the sheet roll. The first motor rotates the conveyance roller. The second motor rotates the sheet roll as the sheet is conveyed.

The tension estimator estimates the tension of the sheet conveyed by the rotation of the conveyance roller. The measuring device measures a physical quantity related to the rotational movement of the conveyance roller. For example, the controller may be configured to control sheet movement and tension by controlling the first motor and the second motor.

The controller estimates the acceleration torque of the second motor required to rotate the sheet roll in accordance with the acceleration of the conveyance roller, based on the rotational acceleration of the conveyance roller specified from the physical quantity measured by the measuring device.

The controller calculates a feedforward operation amount for the second motor based on the estimated acceleration torque. The controller calculates a feedback operation amount for the second motor based on the estimated tension as the tension estimated by the tension estimator and the target tension.

The controller controls the second motor based on at least one of the calculated feedback operation amount and feedforward operation amount. The controller controls the second motor based on at least the feedforward operation amount of the feedback operation amount and the feedforward operation amount when accelerating the conveyance roller.

According to this sheet conveying device, by estimating the acceleration torque and controlling the second motor based on the estimated acceleration torque, even in an environment where the weight of the sheet roll changes due to sheet consumption, it can be adjusted according to the acceleration of the conveying roller. The second motor can be controlled to rotate the sheet roll at an accelerated rate, and sheet conveyance control that involves an acceleration process can be appropriately performed.

According to another aspect of the present disclosure, the controller may be configured to control the first motor based on the physical quantity measured by the measuring device so that the conveyance roller rotates according to a predetermined speed profile.

According to another aspect of the present disclosure, the acceleration torque is a target rotation of the conveying roller specified from a speed profile instead of or in addition to the rotational acceleration of the conveying roller specified from a physical quantity measured by a measuring instrument. It may be estimated based on acceleration.

That is, the controller is configured to estimate the acceleration torque of the second motor required to rotate the sheet roll in accordance with the acceleration of the transport roller, based on the target rotational acceleration of the transport roller specified from the speed profile. Good too.

According to one aspect of the present disclosure, an image forming system including the above-described sheet conveying device and a recording head may be provided. The recording head can form an image on a sheet conveyed by a sheet conveyance device.

1 is a diagram illustrating a configuration of an image forming system according to one aspect of the present disclosure. It is a figure explaining the function of a tensioner. FIG. 1 is a block diagram illustrating the electrical configuration of an image forming system. 3 is a flowchart showing processing executed by the main controller. FIG. 2 is a block diagram showing the configuration of a speed controller. It is a block diagram showing the composition of a tension controller. 3 is a flowchart showing processing executed by a gain setter. It is a block diagram showing the composition of the tension controller of a second embodiment. FIG. 11 is a block diagram illustrating a configuration of a feedforward controller according to a second embodiment. It is a flowchart partially showing the processing performed by the main controller in the second embodiment.

Exemplary embodiments of the present disclosure will now be described with reference to the drawings.
[First embodiment]
1 is configured to form an image on a sheet Q pulled out from a sheet roll Q0. The image forming system 1 functions as a sheet transport device for transporting the sheet Q below a recording head 40.

The image forming system 1 includes a holder 10 (see FIG. 3), a tensioner 15, a conveyance roller 20, a nip roller 25, a belt mechanism 30, and a recording head 40. In FIG. 1, the configuration downstream of the belt mechanism 30 in the conveying direction of the sheet Q is omitted. For example, a cutter for cutting the sheet Q is provided downstream of the belt mechanism 30.

The holder 10 removably holds the sheet roll Q0. The sheet roll Q0 is configured with the sheet Q wound around a hollow core. The holder 10 includes a rotating shaft 10A that is inserted into the core of the sheet roll Q0, and a holder body (not shown) that rotatably holds the rotating shaft 10A.

The holder main body is fixed within a casing (not shown) of the image forming system 1. The core material of the sheet roll Q0 is fixed to the rotating shaft 10A of the holder 10 so as not to slip. Thereby, the sheet roll Q0 rotates together with the rotating shaft 10A of the holder 10.

After the sheet roll Q0 is attached to the rotating shaft 10A, the sheet Q is manually pulled out from the sheet roll Q0 via the tensioner 15 to a position past the nip point P2 between the conveying roller 20 and the nip roller 25 by the user. Point P1 in FIG. 1 indicates the pull-out point of the sheet Q from the sheet roll Q0.

The conveyance roller 20 rotates and conveys the sheet Q nipped between it and the nip roller 25 in the conveyance direction indicated by the thick arrow. As shown in FIG. 2, the tensioner 15 is configured as a roller that can be displaced in the front-rear direction, and is connected to a spring member 16.

When the tensioner 15 is displaced forward, it is arranged so as to receive a backward biasing force from the spring member 16. The tensioner 15 applies tension to the sheet Q using this biasing force. The front here corresponds to the conveyance direction of the sheet Q, and the rear corresponds to the direction opposite to the conveyance direction of the sheet Q.

The tensioner 15 is displaced forward in response to a pressing force from the sheet Q when the sheet Q pulled out from the sheet roll Q0 is conveyed by the conveyance roller 20. The pressing force corresponds to the tension of the sheet Q. The dotted line shown in FIG. 2 shows a state in which the tensioner 15 and the seat Q shown by the solid line are displaced to the position shown by the dotted line due to the force from the seat Q.

The position of the tensioner 15 in the longitudinal direction is stabilized at a position where the urging force of the spring member 16 and the tension of the sheet Q are balanced. The image forming system 1 is configured to estimate the tension of the sheet Q using the position of the tensioner 15 as an index and perform tension control (details will be described later).

The belt mechanism 30 is disposed downstream of the conveyance roller 20 in the conveyance direction, and conveys the sheet Q conveyed from the conveyance roller 20 further downstream. As shown in FIG. 1, the belt mechanism 30 has a structure in which a belt 33 is wound around a driving roller 31 and a driven roller 32. The drive roller 31 rotates the belt 33 by rotational movement synchronized with the conveyance roller 20 .

The belt mechanism 30 further includes a first opposing roller 35 at a position facing the drive roller 31 with the belt 33 in between, and a second opposing roller 36 at a position facing the driven roller 32 with the belt 33 in between.

As the belt 33 rotates, the sheet Q conveyed from the conveyance roller 20 passes between the first opposing roller 35 and the belt 33 and is conveyed downstream. Further, the sheet Q is conveyed downstream between the second opposing roller 36 and the belt 33. Due to the rotation of the belt 33, the sheet Q is conveyed at the same speed as the conveyance speed of the sheet Q by the conveyance roller 20.

According to one example, the belt mechanism 30 can have an air suction function. That is, the belt 33 may have a large number of minute holes through which air passes, and a suction device (not shown) for sucking air may be provided below the belt 33. The sheet Q may be conveyed while being attracted to the surface of the belt 33 by air suction using a suction device.

The recording head 40 is provided above the belt mechanism 30 and forms an image on the sheet Q passing therethrough. The recording head 40 is a line head, and simultaneously forms an image on the entire line direction of the sheet Q passing below the recording head 40 . The line direction here is a direction along the surface of the sheet Q, and is a direction perpendicular to the conveying direction of the sheet Q, in other words, the longitudinal direction of the sheet Q.

The recording head 40 may be, for example, an inkjet head that forms an image on the sheet Q using an inkjet method. The recording head 40 may be a thermal head that forms an image on the sheet Q using a thermal method or a thermal transfer method.

When the recording head 40 forms an image using an inkjet method, a fixing device 45 for drying and fixing the ink may be provided downstream of the recording head 40 in the transport direction. The fixing device 45 may be provided adjacent to the recording head 40 on the belt mechanism 30, as shown by the dotted line in FIG.

Next, the electrical configuration of the image forming system 1 will be described in detail. As shown in FIG. 3, the image forming system 1 includes a controller 50 that centrally controls the entire system. The image forming system 1 further includes a supply motor 61, a motor driver 63, a rotary encoder 65, and a measurement circuit 67 to control the rotation of the sheet roll Q0 mounted on the holder 10.

The supply motor 61 is connected to the rotating shaft 10A of the holder 10 via a gear (not shown), and is arranged to apply power to the rotating shaft 10A. The rotating shaft 10A of the holder 10 receives power from the supply motor 61 and rotates. The sheet roll Q0 rotates together with the rotating shaft 10A.

Supply motor 61 may be a DC motor. The supply motor 61 generates rotational torque according to the drive current input from the motor driver 63 to drive the rotating shaft 10A. The motor driver 63 inputs a drive current to the supply motor 61 according to the operation amount _USR input from the controller 50.

The rotary encoder 65 is provided on the rotating shaft 10A of the holder 10 or the rotating shaft of the supply motor 61, and outputs an encoder signal according to rotation. The measurement circuit 67 measures the rotational position and rotational speed (in other words, the rotational angle and angular velocity) of the sheet roll Q0 as physical quantities related to the rotational movement of the sheet roll Q0 based on the encoder signal input from the rotary encoder 65, The measured rotational position and rotational speed are input to the controller 50. The rotational position and rotational speed of the rotating shaft 10A correspond to the rotational position and rotational speed of the sheet roll Q0.

The image forming system 1 further includes a transport motor 71, a motor driver 73, a rotary encoder 75, and a measurement circuit 77 as components for controlling the rotation of the transport roller 20.

Conveyance motor 71 may be a DC motor. The conveyance motor 71 is connected to the conveyance roller 20 via a gear, and rotates the conveyance roller 20 by generating rotational torque according to a drive current inputted from a motor driver 73 . The motor driver 73 inputs a drive current corresponding to the operation amount _UPF input from the controller 50 to the transport motor 71.

The rotary encoder 75 is provided on the rotation axis of the conveyance roller 20 or the rotation axis of the conveyance motor 71, and outputs an encoder signal according to rotation. The measurement circuit 77 measures the rotational position and rotational speed (in other words, the rotational angle and angular velocity) of the conveyance roller 20 as physical quantities related to the rotational movement of the conveyance roller 20 based on the encoder signal input from the rotary encoder 75. The measured rotational position and rotational speed are input to the controller 50.

The image forming system 1 further includes a position detector 80 that detects the position of the tensioner 15. The position detector 80 detects a position X of the tensioner 15 in the longitudinal direction with respect to a predetermined origin position, and inputs the detected position X to the controller 50. Position detector 80 may be configured with a linear encoder, for example.

The image forming system 1 further includes a head driver 90, a registration sensor 91, a distance sensor 93, a user interface 95, and a communication interface 97. The head driver 90 is configured to drive the recording head 40 according to a control signal from the controller 50. The registration sensor 91 is configured to detect the leading edge of the sheet Q passing therethrough upstream of the belt mechanism 30 and input the detection signal to the controller 50 .

The distance sensor 93 is arranged at a position facing the sheet roll Q0, and is configured to measure the distance between the distance sensor 93 and the surface of the sheet roll Q0, and input the measurement signal to the controller 50. The distance sensor 93 can measure the distance between the distance sensor 93 and the surface of the sheet roll Q0, for example, by emitting light to the surface of the sheet roll Q0 and receiving the reflected light. The distance sensor 93 may be a sensor that measures distance using ultrasonic waves.

The user interface 95 includes a display section that displays various information for the user, and an input section that accepts operations from the user. For example, the display section is a liquid crystal display, and the input section is a touch panel on the liquid crystal display.

The communication interface 97 is configured to be able to communicate with the information device by wire or wirelessly. The communication interface 97 may be a USB interface or a wired/wireless LAN interface. The information device may be a personal computer or a tablet terminal owned by the user.

The controller 50 includes a main controller 51, a print controller 53, a speed controller 55, and a tension controller 57. The main controller 51 includes a processor 51A and a memory 51B. The memory 51B includes RAM and flash memory.

Processor 51A executes various processes according to computer programs stored in memory 51B. In the following, the processing executed by the main controller 51 may be understood to be executed by the processor 51A according to a computer program.

The print controller 53, speed controller 55, and tension controller 57 are configured by, for example, ASIC. The print controller 53 inputs a control signal to the head driver 90 to cause the recording head 40 to form an image on the sheet Q based on the image data to be printed, which is input from the main controller 51. do.

The speed controller 55 determines a manipulated _{variable UPF} for the transport motor 71 so that the transport roller 20 rotates at a target rotational speed according to instructions from the main controller 51, and inputs the determined manipulated variable _UPF to the motor driver 73. It is configured as follows. According to this embodiment, the conveyance speed of the sheet Q is controlled by controlling the rotational speed of the conveyance roller 20.

The tension controller 57 determines the operation amount _USR for the supply motor 61 so that the sheet Q is conveyed with the target tension according to the instruction from the main controller 51, and applies the determined operation amount _USR to the motor driver 63. configured to input.

When the main controller 51 receives a print command from the information device through the communication interface 97, it executes the process shown in FIG. In cooperation with the print controller 53, speed controller 55, and tension controller 57, each part within the image forming system 1 is controlled.

When starting the process shown in FIG. 4, the main controller 51 executes initial processing (S110). The initial process includes a process of arranging the head of the sheet Q at a predetermined starting point. The starting point may be a position where the leading edge of the sheet Q is detected by the registration sensor 91, or may be a position where the leading edge of the sheet Q is moved a predetermined distance downstream in the conveying direction from this position.

The starting point may be defined as the position where the leading edge of the sheet Q enters the belt mechanism 30, or may be defined as the position on the sheet conveyance path where the recording head 40 forms an image on the sheet Q, which is necessary for accelerating the sheet Q. The point may be a distance upstream in the transport direction.

When the head of the sheet Q is placed at the starting point, the main controller 51 starts the conveyance process of the sheet Q (S120). In the conveyance process, the main controller 51 inputs into the speed controller 55 a speed profile indicating the target rotational speed of the conveyance roller 20 until the sheet Q stops at the target stop position, and causes the speed controller 55 to adjust the speed of the conveyance roller 20 according to the speed profile. Execute rotation speed control.

The speed profile indicates a target rotational speed in an acceleration section, a target rotational speed in a constant speed section, and a target rotational speed in a deceleration section. By controlling the rotational speed of the conveyance roller 20 according to this speed profile, the sheet Q accelerates until it reaches a predetermined speed, moves at a constant speed after reaching the predetermined speed, and then decelerates.

In the conveyance process, the main controller 51 further inputs to the tension controller 57 a tension profile indicating the target tension until the sheet Q stops at the target stop position, and causes the tension controller 57 to execute tension control of the sheet Q according to the tension profile. .

After starting the conveyance process, the main controller 51 waits until the rotational speed control shifts to the constant speed section (S130), and when the rotation speed control shifts to the constant speed section, starts the printing process (S140). In the printing process, the main controller 51 causes the print controller 53 to execute drive control of the recording head 40 to cause the recording head 40 to form an image on the sheet Q based on the image data to be printed. Through this control, the recording head 40 repeatedly performs an image forming operation in the line direction on the sheet Q in accordance with the movement in the conveyance direction.

When an image based on the image data to be printed is formed on the sheet Q by the movement of the sheet Q and the synchronized image forming operation of the recording head 40, and the printing process and the conveyance process are completed (Yes in S150), the main controller 51 ends the process. Processing is executed (S160). The termination process includes a process of notifying the user through the user interface 95 of the termination of printing. Thereafter, the main controller 51 ends the process shown in FIG. 4.

Next, the detailed configuration of the speed controller 55 will be explained using FIG. 5. The speed controller 55 adjusts the conveyance roller 20 to the target rotation speed by calculating the operation amount _UPF for the conveyance motor 71 based on the deviation between the rotation speed of the conveyance roller 20 measured by the measurement circuit 77 and the target rotation speed. is configured to provide feedback control. The actual rotational speed hereinafter means a measured value of the rotational speed.

The speed controller 55 includes a speed command device 101 , a deviation calculator 103 , a PID controller 105 , a static friction compensator 107 , and an adder 109 . The speed command device 101 outputs the target rotational speed ω _r at each point in time from the start of control according to the speed profile input from the main controller 51.

The deviation calculator 103 calculates the deviation E _V =(ω _r −ω) between the target rotation speed ω _r from the speed command device 101 and the actual rotation speed ω input from the measurement circuit 77 . The PID controller 105 calculates the operation amount _UV for the transport motor 71 based on the deviation _EV input from the deviation calculator 103.

The PID controller 105 includes a proportional element that amplifies the deviation E _V with a gain G _p and outputs it, an integral element that amplifies the integral value INT (E _V ) of the deviation E _V with a gain G _i and outputs it, and a and a differential element that amplifies the differential value DIF (E _V ) of _V by a gain G _d and outputs the amplified differential value DIF (E V ) of V. The PID controller 105 calculates the sum of the outputs from the proportional element, the integral element, and the differential element as the manipulated variable _UV for the transport motor 71.

The static friction compensator 107 outputs a compensation amount C for compensating for a shortage of the manipulated variables U _{and V} caused by static friction. The compensation amount C is a constant value when the actual rotation speed ω is zero, i.e., in a stationary state, and is zero when the actual rotation speed ω is non-zero, i.e., in a non-stationary state.

The adder 109 corrects the manipulated variable U _V output from the PID controller 105 using the compensation amount C, and inputs the corrected manipulated variable U _PF =U _V +C to the motor driver 73 . The motor driver 73 inputs a drive current corresponding to the manipulated variable _UPF input from the speed controller 55 to the transport motor 71, thereby controlling the transport motor 71 so that a rotational torque corresponding to the manipulated variable _UPF is generated. Drive. The rotation speed of the conveyance roller 20 and the corresponding conveyance speed of the sheet Q are feedback-controlled by this speed controller 55.

Tension control is realized by a tension controller 57 shown in FIG. The tension controller 57 shown in FIG. 6 supplies the sheet Q based on the deviation between the target tension and the tension of the sheet Q estimated from the position The operation amount _USR for the motor 61 is calculated. Thereby, the tension controller 57 feedback-controls the tension of the sheet Q to the target tension.

As shown in FIG. 6, the tension controller 57 includes a tension command device 110, a tension estimator 120, a deviation calculator 130, a PID controller 140, a roll diameter estimator 150, a feedforward controller 160, It includes an adder 170 and a gain setter 180.

The tension command device 110 outputs the target tension T _r at each time point from the start of control according to the tension profile input from the main controller 51 . The tension estimator 120 estimates the tension T acting on the sheet Q based on the position X of the tensioner 15 input from the position detector 80. Specifically, the tension estimator 120 can calculate, as the estimated tension T, a value k·X obtained by multiplying the position X of the tensioner 15 by a specific proportionality coefficient k.

The deviation calculator 130 calculates the deviation E _T =T _r −T between the target tension T _r and the estimated tension T. The PID controller 140 calculates a feedback operation amount U _B for the supply motor 61 based on the deviation E _T inputted from the deviation calculator 130 .

As shown in FIG. 6, the PID controller 140 includes a proportional gain amplifier 141, an integral gain amplifier 142, a differential gain amplifier 143, an integrator 145, a differentiator 146, and an adder 148. The deviation _ET from the deviation calculator 130 is input to a proportional gain amplifier 141, an integrator 145, and a differentiator 146. The proportional gain amplifier 141 amplifies the input deviation E _T by a gain K _p and outputs the amplified deviation E T .

The integrator 145 performs an integral operation on the deviation E _T and inputs an integral value INT (E _T ) of the deviation E _T to the integral gain amplifier 142 . The integral gain amplifier 142 amplifies the input integral value INT(E _T ) of the deviation E _T by a gain K _i and outputs the amplified value.

The differentiator 146 performs a differential operation on the deviation E _T and inputs the differential value DIF (E _T ) of the deviation E _T to the differential gain amplifier 143 . The differential gain amplifier 143 amplifies the input differential value DIF(E _T ) of the deviation E _T by a gain K _d and outputs the amplified value.

The adder 148 outputs the output K _p · _ET from the proportional gain amplifier 141, the output K _i ·INT ( _ET ) from the integral gain amplifier 142, and the output K _d ·DIF (ET ₎ from the differential gain amplifier 143. is added, and the added value K _p · _ET +K _i ·INT( _ET )+K _d ·DIF( _ET ) is output as the feedback operation amount U _B for the supply motor 61.

The adder 170 converts the sum value U _B +U _F of the feedback operation amount U _B inputted from the PID controller 140 and the feedforward operation amount U _F inputted from the feedforward controller 160 into an operation for the supply motor 61 . Output as quantity _USR .

Feedforward controller 160 includes a differentiator 161, an acceleration torque estimator 163, and an FF gain amplifier 165. The differentiator 161 differentiates the rotational speed ω of the conveyance roller 20 inputted from the measurement circuit 77 to calculate the rotational acceleration α of the conveyance roller 20. Rotational acceleration corresponds to angular acceleration. The rotational acceleration α calculated by the differentiator 161 is hereinafter expressed as an actual rotational acceleration α.

The acceleration torque estimator 163 estimates the acceleration torque τ of the supply motor 61 necessary to rotate the sheet roll Q0 in accordance with the acceleration of the conveyance roller 20, in other words, the acceleration of the sheet Q, based on the actual rotational acceleration α. do. Specifically, the actual rotational acceleration α, the roll diameter R which is the radius of the sheet roll Q0, the radius _Rp of the conveying roller 20, and the inertia J(R) of the sheet roll Q0 estimated from the roll diameter R, Based on this, the acceleration torque τ is calculated according to the formula τ=J(R)・(R _p /R)・α.

When the rotational acceleration of the conveyance roller 20 is α, the acceleration of the sheet Q conveyed by the rotation of the conveyance roller 20 is R _p ·α. In order to pull out the sheet Q from the sheet roll Q0 at the same acceleration, the sheet roll Q0 needs to rotate at a rotational acceleration (R _p /R)·α. Assuming that the inertia is J, the acceleration torque required to realize this rotation is J·(R _p /R)·α.

A function J(R) for calculating the inertia J(R) of the sheet roll Q0 when the roll diameter is R is prepared in advance and calculated by the acceleration torque estimator 163. The radius _Rp of the conveyance roller 20 is a fixed value determined by the machine.

The roll diameter R of the sheet roll Q0 is estimated by the roll diameter estimator 150 based on the measurement signal from the distance sensor 93. The measurement signal from the distance sensor 93 represents the distance Z between the surface of the sheet roll Q0 and the distance sensor 93. The distance from the center of the sheet roll Q0 to the distance sensor 93 is a fixed value Z0. The roll diameter estimator 150 can estimate the roll diameter R=Z0−Z of the sheet roll Q0 by subtracting the distance Z from the fixed value Z0.

The acceleration torque estimator 163 calculates the acceleration torque τ based on the information on the roll diameter R input from the roll diameter estimator 150 and based on the above equation. The FF gain amplifier 165 adjusts the calculated acceleration torque τ to be amplified by the gain _KFF , and outputs the adjusted acceleration torque _KFF ·τ as the feedforward manipulated variable _UF . Normally, the gain K _FF has a value of 1, but it can be finely adjusted from the value 1 depending on the mechanical characteristics of the rotating system.

The motor driver 63 inputs to the supply motor 61 a drive current corresponding to the above-mentioned manipulated variable U _SR =U _F +U _B that includes the feedforward manipulated variable U _F calculated in this way as a component, thereby increasing the manipulated variable U The supply motor 61 is driven so that a rotational torque corresponding to _SR is generated. By performing feedforward control and feedback control on the supply motor 61 in this manner, the tension of the sheet Q is controlled to the target tension.

In this embodiment, the gain setter 180 is further configured to adjust the gains K _p , K _i , and K _d in the PID controller 140 based on the roll diameter R estimated by the roll diameter estimator 150 . The gains K _p , K _i , and K _d are calculated according to the functions K _p (R), K _i (R), and K _d (R) with the roll diameter R as a variable, and when the roll diameter is R, K _p =K _p ( R), K _i =K _i (R), and K _d =K _d (R). The functions K _p (R), K _i (R), and K _d (R) are determined in advance through tests.

Specifically, the gain setter 180 adjusts the gains K _p , K _i , and K _d by repeatedly executing the process shown in FIG. 7 . When the process shown in FIG. 7 is started, the gain setter 180 sets the functions K _p (R), K _i (R), K _d (R) based on the latest roll diameter R estimated by the roll diameter estimator 150. Accordingly, the gains K _p =K _p (R), K _i =K _i (R), and K _d =K _d (R) to be set in the PID controller 140 are calculated (S210).

The gain setter 180 further judges whether the rotation speed control is in a constant speed section (S220). If the judgment is affirmative, the gain setter 180 sets the gains _Kp = _Kp (R), _Ki = Ki (R), and _Kd = _Kd ( _R ) calculated in S210 in the PID controller 140, thereby updating the gains _Kp , _Ki , and _Kd to values corresponding to the roll diameter R (S240). Then, the process shown in FIG. 7 is terminated.

If the determination in S220 is negative, the gain setter 180 corrects the gains _Kp = _Kp (R), _Ki = _Ki (R), and _Kd = _Kd (R) calculated in S210 to smaller values (S230). For example, the gain setter 180 can correct the gains _Kp = Kp (R), _Ki = _Ki (R), and _Kd = _Kd (R) calculated in S210 to values _Kp = _hKp (R), _Ki = _hKi (R), and _Kd = _hKd ( _R ) multiplied by a coefficient h that is less than 1.

After that, the gain setter 180 sets the gain after the correction in S230 to the PID controller 140 (S240). After executing the process in S240, the gain setter 180 ends the process shown in FIG. The gain setter 180 repeatedly executes such processing.

According to the image forming system 1 of the present embodiment described above, the rotational acceleration α of the transport roller 20 is determined by differentiating the rotational speed ω of the transport roller 20 measured by the rotary encoder 75 and the measurement circuit 77. Based on the identified rotational acceleration α of the conveyance roller 20, the acceleration torque τ of the supply motor 61 required to rotate the sheet roll Q0 in accordance with the acceleration of the conveyance roller 20 is calculated.

The controller 50 calculates a feedforward operation amount _UF for the supply motor 61 based on the calculated acceleration torque τ. The controller 50 further estimates the tension of the sheet Q based on the position X of the tensioner 15. The controller 50 calculates a feedback operation amount U _B for the supply motor 61 based on the deviation between the estimated tension T and the target tension T _r .

The controller 50 calculates an operation amount USR for the supply motor ₆₁ based on the feedback operation amount U _B and the feedforward operation amount U _F , and a drive current corresponding to the calculated operation amount U _SR is input to the supply motor 61. The supply motor 61 is controlled as follows.

According to this image forming system 1, the component of the feedforward operation amount _UF included in the operation amount _USR functions meaningfully during the process in which the sheet Q is acceleratedly conveyed by the rotation of the conveyance roller 20.

That is, in accordance with the acceleration of the sheet Q due to the rotation of the conveyance roller 20, the sheet roll Q0 rotates so that the sheet Q is pulled out from the sheet roll Q0. The feedforward operation amount _UF compensates for the acceleration torque according to the inertia of the sheet roll Q0.

According to this embodiment, in order for the feedforward control to function meaningfully, the gains K _p , K _i , K _d of the PID controller 140 are adjusted to be smaller during acceleration than during constant speed, and the feedback operation amount U _B is It can be suppressed. In the constant speed section, since the rotational acceleration α is approximately zero, feedforward control hardly functions, and feedback control functions meaningfully.

In this embodiment, the sheet Q wound around the sheet roll Q0 decreases with use, and the radius R of the sheet roll Q0, the weight of the sheet roll Q0, and the inertia J(R) change, but the controller 50 estimates The inertia J(R) of the sheet roll Q0 is estimated based on the radius R of the sheet roll Q0. The controller 50 estimates the acceleration torque τ according to the inertia J(R) based on the inertia J(R) and the rotational acceleration α of the conveyance roller 20.

According to this embodiment, the deviation E _T between the estimated tension T and the target tension T _r , the integral value of the deviation E _T , and the differential value of the deviation E _T correspond to the gains K _p , K _i , and K _d . The feedback operation amount _UB corresponding to the amplified value is calculated. Then, the gains K _p , K _i , and K _d are adjusted to values corresponding to the diameter R of the sheet roll Q0, as described above.

Therefore, according to the present embodiment, even immediately after a new sheet roll Q0 is attached to the holder 10, immediately before the sheet Q is removed from the sheet roll Q0, and even during acceleration and constant speed, the supply motor 61 can be appropriately controlled.

In other words, the controller 50 can appropriately control the transport speed and tension of the sheet Q in conjunction with each other while suppressing the influence of the remaining amount and motion state of the sheet roll Q0. The sheet Q can be appropriately conveyed with good control. Therefore, it is possible to suppress the occurrence of skew of the sheet Q and the occurrence of errors in the conveyance speed and stop position of the sheet Q due to excess or deficiency of tension.

As described above, according to the technology of the present disclosure, in an environment where the weight of the sheet roll Q0 changes as the sheet Q is consumed, it is possible to appropriately perform conveyance control of the sheet Q that involves an acceleration process.

In the embodiment described above, the operation amount U _SR including the feedforward operation amount U _F and the feedback operation amount U _B is calculated for the supply motor 61 regardless of whether it is in the acceleration section or not. However, the tension controller 57 may calculate the manipulated variable U _SR including only the feedback manipulated variable U _B in the constant speed section. That is, the tension controller 57 may calculate the manipulated variable _USR so as not to include the feedforward manipulated variable _UF .

The tension controller 57 may calculate the manipulated variable U _SR that includes only the feedforward manipulated variable U _F in a non-constant speed section, particularly in an acceleration section. That is, the tension controller 57 may calculate the operation amount _USR so as not to include the feedback operation amount _UB .

The controller 50 can control the supply motor 61 based on at least one of the feedback operation amount U _B and the feedforward operation amount U _F , and when the conveyance roller 20 is accelerated, the feedback operation amount U _B and the feedforward operation amount U are controlled. The supply motor 61 can be controlled based on at least the feedforward operation amount _UF of _F. The controller 50 can control the supply motor 61 based on at least the feedback operation amount _UB when the conveyance roller 20 rotates at a constant speed.

The holding structure of the sheet roll Q0 by the holder 10 and the driving method of the sheet roll Q0 are not limited to the above embodiment. The image forming system 1 in which the core material of the sheet roll Q0 is inserted into the rotating shaft 10A of the holder 10 has been described above.

However, the holder may also be constructed from a hollow cylindrical material having a space inside to accommodate the sheet roll Q0. The holder may be configured such that the inner surface defining the accommodation space for the sheet roll Q0 rotates. The sheet roll Q0 may be rotated in a state accommodated in the holder according to rotation of the inner surface of the holder. In addition, a roller may be provided that contacts the outer peripheral surface of the sheet roll Q0. The sheet roll Q0 may be rotated by the rotation of this roller.

[Second embodiment]
Next, an image forming system 1 according to a second embodiment will be described. The image forming system 1 of the second embodiment is an image forming system that is partially different from the first embodiment. In the following, parts of the image forming system 1 of the second embodiment that are configured similarly to those of the first embodiment are given the same reference numerals as those of the first embodiment, and explanations of the parts are omitted. A configuration of the image forming system 1 that is different from the first embodiment will be selectively explained.

In the second embodiment, the controller 50 includes a tension controller 200 shown in FIG. 8 instead of the tension controller 57 shown in FIG. The tension controller 200 includes a tension command device 110, a tension estimator 120, a deviation calculator 130, a PID controller 140, a roll diameter estimator 150, a gain setting device 180, a first-order lag filter 210, and a target speed. It includes a generator 220, a deviation calculator 230, an adder 240, a feed rate controller 250, a feedforward controller 260, and an adder 270.

The deviation calculator 130 calculates the deviation E _T =T _r −T between the target tension T _r from the tension command device 110 and the estimated tension T from the tension estimator 120, as in the first embodiment. The PID controller 140 calculates the tension operation amount U _T =K _p・_ET +K _i・INT(ET)+K _d・DIF( _{ET )} based on the deviation E _T inputted from the deviation calculator 130. .

The tension operation amount U _T corresponds to the feedback operation amount U _B of the first embodiment. The gain setter 180 is configured to adjust the gains K _p , K _i , and K _d in the PID controller 140 based on the roll diameter R estimated by the roll diameter estimator 150 .

The target speed generator 220 generates a target rotational speed ω _r of the conveying roller 20 that is input from the speed command unit 101 of the speed controller 55 via the first-order lag filter 210 and a roll diameter R estimated by the roll diameter estimator 150. Based on this, the target rotational speed ω _sr of the sheet roll Q0 is calculated.

The target speed generator 220 calculates the target rotational speed ω _sr according to the formula ω _sr = (R _p /R)·ω _r so that the conveyance roller 20 and the sheet roll Q0 rotate at the same circumferential speed. I can do it. R _p is the radius of the conveyance roller 20 as described above. The target rotational speed ω _sr of the sheet roll Q0 corresponds to the target rotational speed ω _sr of the rotating shaft 10A.

The deviation calculator 230 calculates the deviation E _W =(ω _sr - ω _s ) between the target rotation speed ω _sr from the target speed generator 220 and the rotation speed ω _s of the sheet roll Q0 measured by the measurement circuit 67. do. The rotational speed ω _s of the sheet roll Q0 corresponds to the angular velocity of the sheet roll Q0 or the rotating shaft 10A.

The adder 240 adds the deviation E _W to the tension operation amount U _T from the PID controller 140 to calculate the operation amount U _C =( _UT + E _w ). The supply speed controller 250 is configured as a PID controller, and calculates a feedback manipulated variable U _B ^* by adding a speed control component to the manipulated variable U _C from the adder 240 . The feedback operation amount U _B ^* is input to the adder 270 as a substitute for the feedback operation amount U _B in the first embodiment.

The supply speed controller 250 includes a proportional gain amplifier 251, an integral gain amplifier 252, a differential gain amplifier 253, an integrator 255, a differentiator 256, and an adder 258. The manipulated variable _UC from the adder 240 is input to a proportional gain amplifier 251, an integrator 255, and a differentiator 256. The proportional gain amplifier 251 amplifies the input manipulated variable U _C by a gain K _wp and outputs it.

The integrator 255 inputs the integral value INT(U _C ) of the manipulated variable U _C to the integral gain amplifier 252 . The integral gain amplifier 252 amplifies the input integral value INT(U _C ) with a gain K _wi and outputs the amplified value. The differentiator 256 inputs the differential value DIF (U _C ) of the manipulated variable U _C to the differential gain amplifier 253 . The differential gain amplifier 253 amplifies the input differential value DIF (U _C ) by a gain K _wd and outputs the amplified value.

The adder 258 outputs the output K _wp ·U _C from the proportional gain amplifier 251, the output K _wi ·INT (U _C ) from the integral gain amplifier 252, and the output K _wd ·DIF (U _C ) from the differential gain amplifier 253. are added, and the added value K _wp ·U _C +K _wi ·INT (U _C )+K _wd ·DIF (U _C ) is output as the feedback operation amount U _B ^* .

As shown in FIG. 9, the feedforward controller 260 includes a differentiator 261, an acceleration torque estimator 263, a viscous friction estimator 265, a dynamic friction estimator 267, and adders 268 and 269. The differentiator 261 differentiates the target rotational speed ω _r of the conveyance roller 20 inputted from the first-order lag filter 210 to calculate the target rotational acceleration α _r of the conveyance roller 20 .

The acceleration torque estimator 263 estimates the acceleration torque τ of the supply motor 61 required to rotate the sheet roll Q0 according to the acceleration of the conveyance roller 20 based on the target rotational acceleration α _r . _{Specifically ,} the inertia J (R ), the acceleration torque τ is calculated according to the formula τ=J(R)・(R _p /R)・α _r .

The viscous friction estimator 265 estimates the viscous friction torque τ _vf in the rotation system of the sheet roll Q0 based on the target rotational speed ω _r of the conveyance roller 20 inputted from the first-order lag filter 210 . The viscous friction torque τ _vf may be calculated according to the formula τ _vf =C _vf ·(R _p /R)·ω _r . C _vf corresponds to the viscous friction coefficient. (R _p /R)·ω _r is the target rotational speed ω _sr of the sheet roll Q0 or the rotating shaft 10A, as described above.

The dynamic friction estimator 267 estimates the dynamic friction torque τ _df in the rotation system of the sheet roll Q0 based on the target rotational speed ω _r of the conveying roller 20 inputted from the first-order lag filter 210 . Specifically, when the target rotational speed ω _r is non-zero, the dynamic friction estimator 267 calculates the dynamic friction torque τ _df =C _df ·N(R) in the rotation system of the sheet roll Q0 based on the dynamic friction coefficient C _df . calculate. N(R) is the drag force N according to the roll diameter R.

The dynamic friction estimator 267 calculates the dynamic friction torque τ _df =0 when the target rotational speed ω _r is zero. Alternatively, when the target rotational speed ω _r is zero, the dynamic friction estimator 267 calculates the static friction torque τ _sf =C _sf ·N(R) in the rotation system of the sheet roll Q0 based on the static friction coefficient C _sf , and the dynamic friction torque τ It may also be calculated as _df .

The adder 268 adds up the dynamic friction torque τ _df input from the kinetic friction estimator 267 and the viscous friction torque τ _vf input from the viscous friction estimator 265, and calculates the friction torque τ _f =τ _vf +τ _df . calculate.

The adder 269 adds the friction torque τ _f input from the adder 268 to the acceleration torque τ input from the acceleration torque estimator 263 to calculate the feedforward operation amount _UF ^* = τ + τ _f . The feedforward manipulated variable U _F ^* thus obtained is input to the adder 270 . The feedforward manipulated variable U _F ^* corresponds to the manipulated variable obtained by adding a friction compensation component to the feedforward manipulated variable U _F calculated by the feedforward controller 160 of the first embodiment.

The adder 270 calculates an added value U _B ^{* +} U _F * of the feedback manipulated variable U _B ^* inputted from the supply speed controller 250 and the feedforward manipulated variable U _F ^* inputted from the feedforward controller 260, It is output as the manipulated variable _USR for the supply motor 61.

The tension controller 200 of the second embodiment described above can achieve precise rotation control of the sheet roll Q0, taking into account the friction torque generated by the rotation system of the sheet roll Q0.

In the second embodiment, unlike the first embodiment, the feedforward controller 260 calculates the feedforward operation amount U _F ^* based on the target rotational speed ω _r instead of the actual rotational speed ω of the conveyance roller 20. This is also significant.

A power transmission system such as gears is present between the supply motor 61 and the rotating shaft 10A of the holder 10. Therefore, there is a time lag before the drive of the supply motor 61 is reflected in the rotational movement of the sheet roll Q0. This time lag may cause a control error when the feedforward operation amount _UF is calculated based on the actual rotational speed ω of the conveyance roller 20 and the supply motor 61 is controlled.

On the other hand, when calculating the feedforward operation amount U _F ^* based on the target rotational speed ω _r of the conveyance roller 20 as in the second embodiment, the influence of the time lag is suppressed and the supply motor 61 is The rotational movement of the sheet roll Q0 can be controlled.

However, when the feedforward manipulation variable U _{F *} is calculated using the target rotational speed ^ωr , it is preferable to perform tensioning on the sheet Q before starting the conveying process of the sheet Q so that the target rotational speed _ωr accurately represents the movement of the sheet Q.

In the second embodiment, the main controller 51 executes the tensioning process (S115) shown in FIG. 10 before starting the conveyance process for the sheet Q in S120. In S115, the main controller 51 causes the tension controller 57 to rotate the supply motor 61 in the opposite direction until the estimated tension T reaches the reference tension T0 while the conveyance roller 20 is stopped.

When the supply motor 61 rotates in the forward direction, the sheet Q is sent out in the transport direction. In S115, the supply motor 61 rotates in the opposite direction while the conveyance roller 20 is stopped, so that the sheet Q is partially rewound onto the sheet roll Q0, and tension is applied to the sheet Q.

The reference tension T0 is the target tension T _r at the start of the conveyance process of the sheet Q in S120, or a tension in the vicinity thereof. In the conveyance process (120) of the sheet Q after execution of this tensioning process (S115), the tension of the sheet Q substantially matches the target tension _Tr from the beginning, and the conveyance roller 20 and the sheet roll Q0 are , rotate at approximately the same circumferential speed.

That is, depending on the execution of the tensioning process (S115), in the subsequent conveyance process (S120), since the target rotational speed ω _r well represents the actual movement of the sheet Q, the conveyance control of the sheet Q is appropriately executed. be able to.

Although the exemplary embodiments of the present disclosure including the first embodiment and the second embodiment have been described above, the present disclosure is not limited to the above-described exemplary embodiments, and may take various aspects. be able to.

For example, the tensioning process (S115) can also be executed in the first embodiment. Like the feedforward controller 260 of the second embodiment, the feedforward controller 160 in the first embodiment estimates the viscous friction torque and/or the kinetic friction torque, and adds the viscous friction torque and/or the kinetic friction to the acceleration torque τ. The feedforward operation amount _UF may be calculated by adding torque. In this case, the feedforward controller 160 may estimate the viscous friction torque and/or the dynamic friction torque based on the actual rotational speed ω instead of the target rotational speed ω _r . Similarly, the actual rotation speed ω may be input to the feedforward controller 260 of the second embodiment instead of the target rotation speed ω _r .

The technology disclosed herein may be applied to various image forming systems. For example, the technology disclosed herein may be applied to an image forming system that does not include a belt mechanism 30. In this case, the image forming system may be provided with a platen for supporting the sheet Q instead of the belt mechanism 30.

The technology of the present disclosure may be applied to an image forming system including a serial drive type recording head instead of a line head as the recording head 40. In this case, the recording head reciprocates in the line direction to form an image on the sheet Q. The technology of the present disclosure may be applied to an electrophotographic image forming system.

The technology of the present disclosure may be applied to a system that forms an image on the front surface of the sheet Q facing outward in the radial direction of the sheet roll Q0, or on the back surface of the sheet Q facing inward in the radial direction of the sheet roll Q0. It may also be applied to a system that forms an image using The technology of the present disclosure may be applied to a system that forms images on both sides of the sheet Q.

The technology of the present disclosure is not limited to application to a system that forms an image on a sheet Q using a coloring material. For example, the technology of the present disclosure may be applied to a system that makes holes in the sheet Q to mark it, or may be applied to a system that sterilizes the surface of the sheet Q by irradiating the surface with light. The technology of the present disclosure may be applied to a system that forms a wiring pattern on a sheet-like substrate. The sheet roll Q0 and the sheet Q may be made of paper, vinyl, or a flexible printed circuit board (FPC).

This disclosure does not limit the configuration of tensioner 15 and tension estimator 120. The tensioner may be constructed of an arm that is pivoted at one end and has a roller at the other end, such as a pendulum arm. The tensioner may include an actuator to apply tension to the sheet Q, and the tension may be estimated from the amount of change in the actuator. A dedicated sensor may be provided for tension estimation. The sensor can act on the tensioner 15 or the sheet Q to detect tension. The technology of the present disclosure does not limit the configuration of the rotary encoders 65, 75. The rotary encoders 65 and 75 may be magnetic rotary encoders instead of optical rotary encoders.

In the above embodiment, the roll diameter R is measured using the distance sensor 93, but the roll diameter R may be estimated without using the distance sensor 93. For example, the roll diameter R may be estimated from the conveyance amount of the sheet Q by the conveyance roller 20 and the corresponding rotation amount of the sheet roll Q0. The conveyance amount of the sheet Q can be specified from the rotation amount of the conveyance roller 20. The amount of rotation (in other words, the rotation angle) of the conveyance roller 20 and the sheet roll Q0 can be measured based on the outputs of the rotary encoders 65 and 75.

The print controller 53, speed controller 55, and tension controller 57, 200 may be configured by a combination of a CPU and an ASIC. The number and presence or absence of CPUs and ASICs in each of the controller 50, main controller 51, print controller 53, speed controller 55, and tension controllers 57, 200 are not limited to the specific example described above.

In addition, the PID controllers 105 and 140 used for feedback control may be replaced with other controllers such as a PI controller. Some of the gains K _p , K _i , and K _d may not be updated based on the roll diameter R. In the second embodiment, the gains K _wp , K _wi , and K _wd may also be updated based on the roll diameter R, similar to the gains K _p , K _i , and K _d .

The function that one component in the above exemplary embodiment has may be distributed and provided to a plurality of components. Functions possessed by multiple components may be integrated into one component. Some of the configurations of the exemplary embodiments described above may be omitted. All aspects included in the technical idea specified from the words described in the claims are embodiments of the present disclosure.

Finally, we will explain the correspondence between terms. The transport motor 71 corresponds to an example of a first motor, and the supply motor 61 corresponds to an example of a second motor. The rotary encoder 75 and the measurement circuit 77 correspond to an example of a measuring device, and the distance sensor 93 and the roll diameter estimator 150 correspond to an example of a roll diameter measuring device. The rotary encoder 65 and the measuring circuit 67 correspond to an example of a roll measuring device.

DESCRIPTION OF SYMBOLS 1... Image forming system, 10... Holder, 10A... Rotating shaft, 15... Tensioner, 20... Conveyance roller, 25... Nip roller, 30... Belt mechanism, 40... Recording head, 50... Controller, 51... Main controller, 51A... Processor , 51B...memory, 53...print controller, 55...speed controller, 57...tension controller, 61...supply motor, 63...motor driver, 65...rotary encoder, 67...measuring circuit, 71...transport motor, 73...motor driver, 75... Rotary encoder, 77... Measurement circuit, 80... Position detector, 93... Distance sensor, 101... Speed command, 103... Deviation calculator, 105... PID controller, 110... Tension command, 120... Tension estimator , 130... Deviation calculator, 140... PID controller, 141... Proportional gain amplifier, 142... Integral gain amplifier, 143... Differential gain amplifier, 150... Roll diameter estimator, 160... Feed forward controller, 161... Differentiator, 163... Acceleration torque estimator, 180... Gain setter, 200... Tension controller, 220... Target speed generator, 230... Deviation calculator, 240... Adder, 250... Supply speed controller, 260... Feedforward controller, 261...differentiator, 263...acceleration torque estimator, 265...viscous friction estimator, 267...dynamic friction estimator.

Claims (18)

a holder that holds a sheet roll around which the sheet is wound;
a conveyance roller that rotates and conveys the sheet pulled out from the sheet roll;
a first motor that rotates the conveyance roller;
a second motor that rotates the sheet roll as the sheet is conveyed;
a tension estimator that estimates the tension of the sheet conveyed by rotation of the conveyance roller;
a measuring device that measures a physical quantity related to the rotational movement of the conveyance roller;
controller and
Equipped with
The controller includes:
Based on the rotational acceleration of the conveyance roller specified from the physical quantity measured by the measuring device, an acceleration torque of the second motor necessary for rotating the sheet roll in accordance with the acceleration of the conveyance roller is estimated. ,
Calculating a feedforward operation amount for the second motor based on the estimated acceleration torque,
Calculating a feedback operation amount for the second motor based on the estimated tension as the tension estimated by the tension estimator and the target tension;
controlling the second motor based on at least one of the calculated feedback operation amount and the feedforward operation amount;
When accelerating the conveyance roller, the second motor is controlled based on at least the feedforward operation amount of the feedback operation amount and the feedforward operation amount. The controller calculates an operation amount for the first motor based on a deviation between a rotation speed of the conveyance roller and a target rotation speed specified from the physical quantity measured by the measuring device, and adjusts the operation amount to the calculated operation amount. The sheet conveying device according to claim 1, wherein the first motor is controlled based on the first motor. a holder that holds a sheet roll around which the sheet is wound;
a conveyance roller that rotates and conveys the sheet pulled out from the sheet roll;
a first motor that rotates the conveyance roller;
a second motor that rotates the sheet roll as the sheet is conveyed;
a tension estimator that estimates the tension of the sheet conveyed by rotation of the conveyance roller;
a measuring device that measures a physical quantity related to the rotational movement of the conveyance roller;
controller and
Equipped with
The controller includes:
controlling the first motor based on the physical quantity measured by the measuring device so that the conveying roller rotates according to a predetermined speed profile;
Based on the target rotational acceleration of the conveyance roller specified from the speed profile, estimate the acceleration torque of the second motor necessary to rotate the sheet roll in accordance with the acceleration of the conveyance roller,
Calculating a feedforward operation amount for the second motor based on the estimated acceleration torque,
Calculating a feedback operation amount for the second motor based on the estimated tension as the tension estimated by the tension estimator and the target tension;
controlling the second motor based on at least one of the calculated feedback operation amount and the feedforward operation amount ;
As a mode of controlling the second motor,
A mode in which the second motor is controlled based on both the feedback operation amount and the feedforward operation amount;
A mode in which the second motor is controlled based only on the feedforward operation amount of the feedback operation amount and the feedforward operation amount ;
including
Sheet conveyance device. The sheet conveying device according to any one of claims 1 to 3, wherein the controller determines the diameter of the sheet roll and estimates the acceleration torque based on the diameter of the sheet roll. The controller determines the diameter of the sheet roll, calculates the inertia in the rotation system of the sheet roll based on the diameter of the sheet roll, and calculates the acceleration based on the inertia and the rotational acceleration of the conveyance roller. The sheet conveying device according to claim 1 or 2, wherein torque is estimated. The controller determines the diameter of the sheet roll, calculates the inertia in the rotation system of the sheet roll based on the diameter of the sheet roll, and calculates the inertia in the rotation system of the sheet roll based on the inertia and the target rotational acceleration of the conveyance roller. The sheet conveyance device according to claim 3, wherein the acceleration torque is estimated. The controller:
A viscous friction torque in a rotation system of the sheet roll is estimated based on the diameter of the sheet roll and the physical quantity measured by the measuring device;
The sheet conveying device according to claim 5 , further comprising a feedforward operation amount for the second motor, the feedforward operation amount being calculated based on the estimated acceleration torque and the estimated viscous friction torque. The controller includes:
Estimating the viscous friction torque in the rotation system of the sheet roll based on the diameter of the sheet roll and the speed profile,
The sheet conveying device according to claim 6, wherein a feedforward operation amount for the second motor is calculated based on the estimated acceleration torque and the viscous friction torque. The sheet conveying device according to claim 7 or claim 8, wherein the controller further estimates a kinetic friction torque and calculates a feedforward operation amount for the second motor based on the estimated acceleration torque, the viscous friction torque, and the kinetic friction torque. comprising a roll diameter measuring device for measuring the diameter of the sheet roll,
The sheet conveying device according to any one of claims 4 to 9, wherein the controller determines the diameter of the sheet roll measured by the roll diameter measuring device based on input from the roll diameter measuring device. The controller includes:
The input value is amplified by an amount corresponding to a preset gain using at least one of a deviation between the estimated tension and the target tension, an integral value of the deviation, and a differential value of the deviation as an input value. Calculating the feedback operation amount based on the value,
The sheet conveyance device according to any one of claims 4 to 10, wherein the gain is set to a value corresponding to the diameter of the sheet roll. A roll measuring device that measures a physical quantity related to the rotational movement of the sheet roll,
The controller includes:
Calculating a manipulated variable based on a tension deviation and a speed deviation as the feedback manipulated variable,
The tension deviation is a deviation between the estimated tension and the target tension,
The speed deviation is a deviation between a target rotational speed of the sheet roll and a rotational speed of the sheet roll specified from a physical quantity measured by the roll measuring device. sheet conveyance device. A roll measuring device that measures a physical quantity related to the rotational movement of the sheet roll,
The controller includes:
Calculating a manipulated variable based on a tension deviation and a speed deviation as the feedback manipulated variable,
The tension deviation is a deviation between the estimated tension and the target tension,
The speed deviation is between a target rotational speed of the sheet roll based on a target rotational speed of the conveyance roller specified from the speed profile, and a rotational speed of the sheet roll specified from a physical quantity measured by the roll measuring device. 9. The sheet conveying device according to claim 3, 6, or 8, wherein the deviation is . The controller includes:
When the conveyance roller is accelerated, the second motor is controlled based on both the feedback operation amount and the feedforward operation amount, and when the conveyance roller is rotating at a constant speed, the second motor is controlled based on at least the feedback operation amount. control the second motor;
The input value is amplified by an amount corresponding to a preset gain using at least one of a deviation between the estimated tension and the target tension, an integral value of the deviation, and a differential value of the deviation as an input value. Calculating the feedback operation amount based on the value,
3. The sheet conveyance device according to claim 1 , wherein the gain is set to a lower value when the conveyance roller is accelerated than when the conveyance roller is rotated at a constant speed. The controller determines the sum of the calculated feedback operation amount and the feedforward operation amount as the operation amount for the second motor, regardless of whether the conveyance roller is accelerating or not. The sheet conveyance device according to claim 1 or 2, wherein the second motor is controlled. a movable tensioner that contacts the sheet pulled out from the sheet roll and applies tension to the sheet;
Sheet transport according to any one of claims 1 to 15, wherein the tension estimator is configured to estimate the tension of the sheet based on the position of the tensioner that moves due to contact with the sheet. Device. 17. The controller controls the second motor so that the tension of the sheet corresponds to the target tension before the first motor starts rotating the transport roller. The sheet conveying device according to any one of the above. A sheet conveying device according to any one of claims 1 to 17,
a recording head for forming an image on a sheet conveyed by the sheet conveying device;
An image forming system comprising:

Images