JP2012254537A - Recording device and control method of roll paper transportation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always impart proper back tension to roll paper while sufficiently following a variation of transportation roll paper.SOLUTION: This recording device which feeds the roll paper wound with a sheet of paper in a roll shape by using a paper feed motor, grips the end of the fed roll paper, intermittently transports the roll paper by using a transportation roller for transporting the roll paper and performs recording has the following constitution. That is, the recording device PWM-controls the paper feed motor even after the feed of the roll paper, and performs control so as to impart the back tension to the roll paper. In other words, the device detects a current supplied to the paper feed motor, compares the detected current with a target current value which is imparted to the paper feed motor following the intermittent transportation of the roll paper, and outputs the comparison result as a feedback signal. Then, in the control, the device changes a duty ratio of the PWM control signal by using a first correction value if the roll paper is in a steady state, and if the roll paper is in a transition state, the device performs control so that the duty ratio of the PWM signal is changed by using a second correction time larger than a first correction time.

Description

  The present invention relates to a recording apparatus and a roll paper conveyance control method. In particular, the present invention relates to a recording apparatus that controls the conveyance of roll paper by driving a paper feed motor such as a DC motor, and a roll paper conveyance control method in the apparatus.

  Conventionally, when a DC motor is used as a recording medium conveyance drive source in a recording apparatus, for example, a DC motor control method disclosed in Patent Document 1 is used. According to the control method, the stability of the control is ensured by limiting the amount of change of the position estimation value and the speed estimation value by the position / speed change limiter.

JP-A-8-130893

  However, the DC motor control as in the conventional example has the following problems.

  That is, the current value supplied to the DC motor changes greatly when a sudden load fluctuation occurs, but the response speed is delayed because the control is performed so as to avoid the sudden change and perform stable operation. .

  For example, when roll paper is fed by a paper feed motor, the leading end is sandwiched between transport rollers in the recording apparatus, and recording is performed while intermittently transporting the roll paper, the roll paper is stopped → accelerated → constant speed Repeat the steps of conveyance → deceleration → stop. Assuming that the roll paper is a load, the load repeatedly fluctuates as the conveyance operation proceeds. In such a recording apparatus, in order to realize high-quality recording, it is important to always apply a constant tension between the roll paper and the conveyance roller so that the roll paper does not loosen. For this reason, control is performed to apply a back tension to the roll paper in the direction opposite to the roll paper conveyance direction.

  A paper feed motor is used as a power source for applying the back tension. When a DC motor is used as the paper feed motor, the DC motor needs to be driven in accordance with the roll paper conveyance status and controlled so that a constant back tension is always applied to the roll paper. However, the drive control by the conventional DC motor cannot sufficiently follow the change of the roll paper that repeats the operation of stop → acceleration → constant speed conveyance → deceleration → stop, and the response becomes slow. For this reason, there is a problem that it is difficult to always give an appropriate back tension to the roll paper.

  The present invention has been made in view of the above-described conventional example, and a recording apparatus capable of sufficiently following the fluctuation of the conveyed roll paper and always applying an appropriate back tension to the roll paper, and the roll paper of the apparatus It is an object of the present invention to provide a conveyance control method.

  In order to achieve the above object, the recording apparatus of the present invention has the following configuration.

  That is, a roll paper in which the paper is wound in a roll shape is rotated by a paper feed motor to feed the paper, and an end of the fed roll paper is sandwiched to rotate a conveyance roller that conveys the roll paper. A recording apparatus for performing recording by intermittently transporting the fed roll paper, the driving means for PWM driving the paper feed motor using a PWM control signal, and the drive after feeding the roll paper A control means for controlling the means to drive the paper feed motor so as to apply a back tension to the roll paper, a detection means for detecting a current supplied to the paper feed motor, and a detection means detected by the detection means. And a comparison means for comparing the current and the target current value applied to the paper feed motor according to the intermittent conveyance of the roll paper, and outputting the comparison result as a feedback signal to the control means. When it is determined by the feedback signal that the roll paper is in a steady state, the control means changes a duty ratio of the PWM control signal using a first correction time, and the roll signal is determined by the feedback signal. When it is determined that the paper is in a transient state, the duty ratio of the PWM control signal is controlled to be changed using a second correction time that is larger than the first correction time.

  According to another invention, the roll paper, in which the paper is wound in a roll shape, is fed by rotating by a paper feed motor, and the roll paper is conveyed with the end of the fed roll paper sandwiched between them. A roll paper conveyance control method for a recording apparatus for performing recording by intermittently conveying the fed roll paper by rotating a roller, wherein the paper feed motor is PWM-driven using a PWM control signal And a control step for controlling the driving process to drive the paper feed motor after the roll paper is fed to apply a back tension to the roll paper, and a current supplied to the paper feed motor. And a control step for comparing the detected current with a target current value applied to the paper feed motor in accordance with the intermittent conveyance of the roll paper, and using the comparison result as a feedback signal. A comparison step to give, and in the control step, when it is determined by the feedback signal that the roll paper is in a steady state, the duty ratio of the PWM control signal is changed using a first correction time. When it is determined by the feedback signal that the roll paper is in a transient state, the duty ratio of the PWM control signal is controlled to be changed using a second correction time that is larger than the first correction time. A roll paper transport control method is provided.

  Therefore, according to the present invention, in intermittent conveyance of roll paper, the duty ratio of the PWM control signal is appropriately changed to apply back tension to the roll paper regardless of whether the roll paper is in a steady state or in a transient state. There is an effect that can be. In particular, in an excessive state, by giving a larger correction time, it is possible to quickly follow a change in the state of the roll paper and always apply an appropriate back tension.

1 is a perspective view illustrating a schematic configuration of an ink jet recording apparatus that is a typical embodiment of the present invention. FIG. 2 is a perspective view illustrating a configuration of a roll paper spool portion in FIG. 1. FIG. 2 is a side sectional view illustrating a schematic configuration of a recording apparatus including the roll paper feeding mechanism illustrated in FIG. 1. It is a top view which shows typically the structure of a roll paper conveyance mechanism. It is a figure which shows the relationship between the LF roller of a roll paper conveyance mechanism, the torque which generate | occur | produces with roll paper, conveyance speed, etc. FIG. FIG. 2 is a block diagram illustrating a configuration of a control unit related to back tension application control of the sheet feeding motor of the recording apparatus illustrated in FIG. 1. It is a block diagram which shows the detailed structure of the controller shown in FIG. 6 is a timing chart of signals related to drive control of a paper feed motor. It is a figure which shows the transition of the data stored in the memory contained in a controller. It is a flowchart which shows the determination process of a PWM control signal.

  Hereinafter, preferred embodiments of the present invention will be described more specifically and in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the already demonstrated part and duplication description is abbreviate | omitted.

  In this specification, “recording” (sometimes referred to as “printing”) is not limited to the case of forming significant information such as characters and graphics, but may be significant. It also represents the case where an image, a pattern, a pattern, etc. are widely formed on a recording medium, or the medium is processed, regardless of whether it is manifested so that humans can perceive it visually. .

  FIG. 1 is a perspective view showing a schematic configuration of an ink jet recording apparatus (hereinafter referred to as a recording apparatus) having a roll paper feeding mechanism as a typical embodiment of the present invention. FIG. 2 is a perspective view showing the configuration of the spool portion of the roll paper in FIG. FIG. 3 is a side sectional view showing a schematic configuration of the recording apparatus including the roll paper feeding mechanism shown in FIG.

  First, a setting operation of roll paper as a recording medium will be described.

  In this embodiment, a roll paper R, which is a continuous paper wound in a roll shape, is used as a recording medium. As shown in the perspective view of FIG. 2, the roll paper R passes the spool shaft 32 through the paper tube S at the winding center. The loading portion 28 of the reference-side roll paper holder 30 disposed on the spool shaft 32 is fixedly held by biting into the inner wall of the paper tube S by the elastic force in the radial direction. The reference side roll paper holder 30 is fixed so as not to rotate with respect to the spool shaft 32.

  Further, the non-reference-side roll paper holder 31 is passed through the spool shaft 32 from the opposite side of the reference-side roll paper holder 30 and set on the paper tube S so as to sandwich the roll paper R. Note that the non-reference-side roll paper holder 31 also has a loading portion 29 that is fixedly held to the paper tube S with an elastic force in the radial direction. As shown in FIG. 1, the roll paper R is also rotatably held by rotatably supporting both ends of the spool shaft 32 by the main body 1 of the recording apparatus. In the following description, the front end portion of the roll paper R is described as Rp.

  Next, the paper feeding operation will be described.

  The leading end Rp of the roll paper R set at the position shown in FIG. 3 is guided to the transport port 2 by the user. Then, when the user rotates the roll paper R in the counterclockwise rotation (CCW) direction, the leading end portion Rp of the roll paper R is sent downstream through the conveyance path. In the middle of the transport path, a reflection type paper detection sensor is provided. When the passage of the leading end Rp of the roll paper R is detected, the transport roller (LF roller) 9 is fed by the transport motor (LF motor) 8. The rotation starts in the CCW direction which is the transport direction.

  The leading end portion Rp of the roll paper R that is subsequently sent downstream by the user reaches the nip portion of the LF roller pair 9, 10, and the paper is placed on the platen 19 while being sandwiched between the LF roller pair 9, 10. Be transported. At this time, the end detection sensor 42 mounted on the carriage 12 detects the passage of the sheet, and confirms that the sheet has surely reached the platen. In the subsequent operations, the paper is automatically conveyed by the LF roller pair 9 and 10, and at this point, the user releases his hand from the roll paper.

  Next, image formation on the roll paper R conveyed to the platen 19 will be described.

  The main body 1 of the recording apparatus is provided with an image recording unit surrounded by a broken line 3 in FIG. The image recording unit 3 includes an ink jet recording head (hereinafter referred to as a recording head) 11, a carriage 12 on which the recording head 11 is placed, and a platen 19 provided to face the recording head 11.

  The recording head 11 includes a plurality of nozzle rows (not shown) in the roll paper transport direction on the surface facing the recording surface, and ejects ink of different colors for each nozzle row. The recording head 11 is supplied with ink of each color from an ink tank 14 via each ink supply tube 13 to each color nozzle. The carriage 12 is supported so as to be slidable along a guide shaft 16 and a guide rail (not shown) which are fixed to both ends of the frame 15 of the main body 1 and arranged in parallel to each other.

  An image is recorded on the roll paper by ejecting ink from the recording head 11 while reciprocating the carriage 12 toward the roll paper conveyed to the image recording unit 3. When an image is recorded by scanning one line by forward scanning or backward scanning of the carriage 12, the roll paper is transported by a predetermined pitch in the transport direction by the LF roller pair 9, 10, and the carriage 12 is moved again to move the next line. Record an image. In this way, the intermittent conveyance of the roll paper is repeated to record an image for one page on the roll paper, and the recorded portion is conveyed to the paper discharge tray 22. When the image recording is completed, the roll paper is conveyed to a predetermined cutting position by the LF roller pair 9 and 10 and cut by the cutter 21.

  The above is a series of flow from roll paper setting to paper discharge.

  FIG. 4 is a top view schematically showing the configuration of the roll paper transport mechanism. The roll paper transport mechanism includes a paper feed motor 34 that applies driving force to the roll paper R, gear trains 35 to 37 that transmit the drive power of the paper feed motor 34 to the spool shaft 32, and a paper feed encoder 38. With this configuration, when the spool shaft 32 rotates, the roll paper R also rotates, and the paper is fed to the LF roller pair 9 and 10.

  FIG. 5 is a diagram illustrating the relationship between the torque generated on the LF roller 9 and the roll paper R of the roll paper transport mechanism, the transport speed, and the like. In FIG. 5, the driving torque of the LF roller 9 is Tlf, the driving torque of the roll paper R is Troll, the torque applied to the paper between the LF roller 9 and the roll paper R is Tpap, the conveyance speed of the LF roller is Vlf, and the roll paper The transport speed is expressed as Vroll, and the paper transport speed is expressed as Vpap. The LF roller transport speed Vlf and the roll paper R transport speed Vroll are circumferential speeds. The driving torque Troll of the roll paper R increases as the amount of roll paper R increases, and decreases as the roll paper winding amount decreases.

  Further, the torque, which is the force of the rotating system, and the rotation directions of Tlf and Troll are directions represented by arrows CCW and CW in the drawing. For Tpap, Vlf, Vroll, and Vpap, the direction of the arrow in the figure is a positive value. The force relationship in the waveform diagram described below will be described based on the direction shown in FIG.

  In this recording apparatus, when the leading edge of the roll paper R is sandwiched between the LF roller pairs 9 and 10 and conveyed by the driving force of the conveyance motor 8, the paper feed motor 34 rotates in the CW (clockwise) direction. Apply back tension to the roll paper. As a result, the torque Tpap is applied to the roll paper R between the LF roller 9 and the spool shaft 32 in the direction opposite to the roll paper conveyance direction. Thereby, a constant tension is applied to the roll paper R during recording.

  FIG. 6 is a block diagram showing a configuration of a control unit related to the back tension application control of the sheet feeding motor of the recording apparatus shown in FIG.

  In this embodiment, as described above, the paper feed motor 34 that is a DC motor operates as a drive source for applying a back tension to the roll paper R.

  The paper feed motor 34 is driven and controlled by a PWM control signal generated by the PWM generation circuit 201. At this time, the direction of the current supplied to the paper feed motor 34 via the H bridge driver 202 is changed, and the rotation direction of the paper feed motor 34 (DC motor) is controlled by the forward / reverse rotation ratio. Since the DC motor has a proportional relationship between torque and current, it can be controlled to the target torque by detecting and feeding back the current.

  As shown in FIG. 6, the voltage detected by the current detection resistor 203 and the differential amplifier 205 and the voltage value converted into the target current are compared by the comparator 206, and the comparison result is sent to the controller 200 as a feedback signal (FB). Supply. Here, the voltage value converted into the target current value is given by the D / A converter 204.

  FIG. 7 is a block diagram showing a detailed configuration of the controller 200.

  In the controller 200, the counter 401 sets the period of the original clock (not shown) as time resolution, and counts down when the feedback signal (FB) is Low during one period of the PWM control signal, and counts up when High. The result counted by the counter 401 in this way is written into the memory 400 after the end of the current detection period (described later). The load variation determination circuit 402 controls the PWM control circuit 403 by a method described later, based on the latest count up / down result counted by the counter 401 and the value stored in the memory 400. Therefore, the feedback signal (FB) itself only expresses the High or Low value, but the High / Low judgment is made many times during one period of the PWM control signal, and the count is increased or decreased each time. Thus, the resulting count value (CNT) has some integer value of zero, positive or negative.

  The PWM control circuit 403 outputs a PWM generation circuit control signal (PWMCNTL) and controls the PWM generation circuit 201. Note that the PWM initial duty value (Duty) is set in the PWM control circuit 403 before starting the feedback control operation.

  FIG. 8 is a timing chart showing the relationship between the PWM control signal output from the PWM generation circuit 201 and the aforementioned feedback signal.

As shown in FIG. 8, the controller 200 performs PWM control of the next cycle based on the feedback signal (FB) measured in the current detection period (P _IDETECT ) set to an arbitrary length not longer than one cycle of the PWM control signal. Determine the signal. Experiments have shown that the feedback signal repeats positive and negative in the steady state and is biased toward the control direction in the transient state.

  In the example shown in FIG. 8, it is shown that the High time of the PWM control signal is lengthened by the period of the next PWM control signal by the feedback signal (FB). The duty ratio is defined as the ratio between the High time and Low time of the PWM control signal or the ratio of the time occupied by High in one period of the PWM control signal. In this embodiment, the following PWM control signal The duty ratio is changed with the period.

  FIG. 9 is a diagram showing the transition of data stored in the memory.

  FIG. 9A shows the initial state of the memory 400, and FIG. 9B shows the state of the memory 400 in which the current of one cycle of the PWM control signal is measured and the first measurement result is written. . Similarly, FIGS. 9C to 9F show the state of the memory 400 in which the second to fifth measurement results are written. In FIG. 9, address indicates a hexadecimal memory address, and data indicates stored data corresponding to the address. This stored data is called a count value.

  Next, a process for determining a PWM control signal for applying a back tension to the roll paper R by PWM driving the paper feed motor 34 in the recording apparatus having the above configuration will be described.

FIG. 10 is a flowchart showing a PWM control signal determination process. In FIG. 10, T ₁ is a correction time used when the load is in a steady state, and T ₂ is a correction time used when the load is in a transient state. T ₁ and T ₂ have a relationship of T ₁ <T ₂ . T _{1 is referred} to as a first correction time, and T _{2 is referred} to as a second correction time. Although the predetermined number of times is described as four, it goes without saying that other values may be used.

  First, in step S1, the value of the feedback signal (FB) continues a predetermined number of times (a predetermined period of the PWM control signal) from the history of the count value (CNT) stored in the memory, and becomes a positive value or a negative value. Find out if you have. The continued value of either positive or negative indicates that the feedback control is biased to, for example, forward rotation or reverse rotation of the paper feed motor. If the forward rotation and reverse rotation of the paper feed motor are reversed appropriately, the load state is normal.If only the forward rotation or reverse rotation of the paper feed motor continues, the load state becomes a transient state. It can be said that there is.

  When recording is performed while intermittently transporting the roll paper, the roll paper repeats the operation of stop → acceleration → constant speed transport → deceleration → stop. Assuming that the roll paper is a load, the load repeatedly fluctuates as the conveyance operation proceeds. In this case, the load is in a steady state when the roll paper is being conveyed at a constant speed or in a stopped state, and the load is in a transient state when the roll paper is being accelerated or decelerated. It can be said.

  Here, if the count value (CNT) has not been positive or negative for a predetermined number of times (the load is in a normal state), the process proceeds to step S2. If it is after the first measurement, since the number of measurements itself is less than 4, the process proceeds to step S2. In contrast, if the count (CNT) continues to be a positive value or a negative value for a predetermined number of times (the load is in a transient state), the process proceeds to step S3.

Now, the process in step S2, and sets the correction time T to T _1, whereas, in step S3, sets the correction time T to T _2, then the process proceeds to step S4. In step S4, it is checked whether the count value (CNT) of the memory is “0”. For example, as shown in FIG. 9A, the count value stored in the memory after the first measurement is “−7”. If CNT = “0”, the process proceeds to step S8. If CNT ≠ “0”, the process proceeds to step S5. In step S8, no processing relating to feedback control is executed.

  In step S5, it is further checked whether CNT <0. If CNT <0, the process proceeds to step S7, and if CNT> 0, the process proceeds to step S6. For example, after the first measurement, since CNT = −7, the process proceeds to step S7. In step S6, the High time of the PWM control signal is shortened by the correction time T, and in Step S7, the High time of the PWM control signal is lengthened by the correction time T. For example, in the example shown in FIG. 8, it is shown that the High time of the PWM control signal is increased in the period of the next PWM control signal by the feedback signal (FB).

For example, after the first measurement, since T = T ₁ , the High time of the PWM control signal is lengthened by T ₁ from the previous value. Similarly, after the second measurement, T = T ₁ and, as shown in FIG. 9C, the count value one PWM cycle before is CNT = 19, so the High time of the PWM control signal is It is lengthened by T ₁ from the value one cycle before. Similarly, after the third and fourth measurements, PWM control in a steady state is performed. In the steady state, the stability is maintained by using the small correction value T ₁ as the correction value for the next PWM control value (see FIGS. 9D to 9E).

Now, as shown in FIG. 9 (f), when the count value continues a positive value a predetermined number of times (here, 4 times), that is, when the load is in a transient state, after the fifth measurement, setting the correction time T to T _2. In the case of FIG. 9F, since CNT> 0, the High time of the PWM control signal is shortened by T ₂ from the previous value.

  Therefore, according to the embodiment described above, if the feedback value does not change according to one of the signs, it is determined that the feedback control does not sufficiently follow the change in load, and a correction value larger than that in the steady state is used. Can do. For example, when T2 = 4 × T1, it is possible to follow up four times faster.

  In the above embodiment, it is determined whether the feedback value is positive or negative for a predetermined number of times, but instead of the predetermined number of times, it is determined whether the total absolute value of the feedback values exceeds a predetermined value. May be.

Claims (6)

The roll paper, in which the paper is wound in a roll shape, is rotated and fed by a paper feed motor, and the conveyance roller that conveys the roll paper sandwiching the end of the fed roll paper is rotated. A recording apparatus that performs recording by intermittently conveying a fed roll paper,
Drive means for PWM driving the paper feed motor using a PWM control signal;
Control means for controlling the drive means after feeding the roll paper to drive the paper feed motor and controlling the roll paper to apply back tension;
Detecting means for detecting a current supplied to the paper feeding motor;
Comparing means for comparing the current detected by the detecting means with a target current value given to the paper feeding motor according to the intermittent conveyance of the roll paper, and outputting the comparison result as a feedback signal to the control means. ,
When it is determined by the feedback signal that the roll paper is in a steady state, the control means changes a duty ratio of the PWM control signal using a first correction time, and the roll signal is determined by the feedback signal. When it is determined that the paper is in a transient state, the recording apparatus controls to change the duty ratio of the PWM control signal using a second correction time that is larger than the first correction time. . The control means includes
A counter that counts the positive and negative of the feedback signal obtained over a time corresponding to one period of the PWM control signal according to a predetermined time resolution;
A memory for storing the count value counted by the counter over a predetermined period of the PWM control signal;
Check whether the count value stored in the memory continues to be a positive value or a negative value over the predetermined period, and the count value continues over the predetermined period, a positive value, or If the roll paper is a negative value, it is determined that the roll paper is in a transient state. If the count value continues for the predetermined period and is not a positive value or a negative value, the roll paper is The recording apparatus according to claim 1, wherein the recording apparatus is determined to be in a steady state.   The recording apparatus according to claim 1, wherein the paper feed motor is a DC motor. The transient state is a state in which the roll paper is accelerated or decelerated in the intermittent conveyance of the roll paper,
4. The steady state is a state in which the roll paper is conveyed at a constant speed or a stopped state in intermittent conveyance of the roll paper. The recording device described in 1.   5. The recording apparatus according to claim 1, wherein the comparison unit performs the comparison and the output of the feedback signal in a time shorter than the period for each period of the PWM control signal. . The roll paper, in which the paper is wound in a roll shape, is rotated and fed by a paper feed motor, and the conveyance roller that conveys the roll paper sandwiching the end of the fed roll paper is rotated. A roll paper conveyance control method for a recording apparatus that performs recording by intermittently conveying a fed roll paper,
A drive step of PWM driving the paper feed motor using a PWM control signal;
A control process for controlling the driving process after feeding the roll paper to drive the paper feed motor and controlling the back tension to be applied to the roll paper;
A detection step of detecting a current supplied to the paper feed motor;
A comparison step of comparing the detected current with a target current value given to the paper feed motor according to the intermittent conveyance of the roll paper, and giving the comparison result to the control step as a feedback signal;
In the control step, when it is determined by the feedback signal that the roll paper is in a steady state, the duty ratio of the PWM control signal is changed using a first correction time, and the roll signal is determined by the feedback signal. Roll paper that controls to change the duty ratio of the PWM control signal using a second correction time that is larger than the first correction time when it is determined that the paper is in a transient state Control method of conveyance.

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