JP2008030465A - Recorder, paper feeder, and method for controlling paper-feeding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recorder which can correctly supply an object under servo control to a target position even when a load suddenly changes, and to provide a paper feeder and a method for controlling paper-feeding. <P>SOLUTION: A conveyance position and a conveyance speed of a recording medium are detected by using an encoder. Then, a conveyance target position of the recording medium is generated by a preliminarily set period. The conveyance target position is corrected. A PWM signal is generated on the basis of the generated or corrected conveyance target position, and the detected and fed-back conveyance position and conveyance speed of the recording medium. A DC motor is servo-controlled by the PWM signal. At this time, the generated or corrected conveyance target position and the detected conveyance position of the recording medium are compared with each other. Control is carried out to make the correction according to the comparison result. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a recording apparatus, a sheet feeding apparatus, and a sheet feeding control method, and in particular, a recording apparatus that supplies a recording medium such as recording paper and discharges ink from a recording head to perform recording on the recording medium. The present invention relates to a paper feed control method.

  In recent years, there are an increasing number of recording apparatuses that employ a DC motor as a driving source, perform high-precision position control by feeding back position detection information by an encoder, and can perform high-speed driving. .

  In particular, the control by the DC motor, unlike the control by the pulse motor, can be rotated at high speed without step-out. In addition, the position information of the motor can be detected with high accuracy by using an encoder signal, and the detection information is fed back to the motor control law to accurately position and control the speed relative to the target position. It is possible.

Such a technique is disclosed in Patent Document 1, for example.
Japanese Patent No. 3352612

  However, in the above conventional example, a target position that gradually increases to the final target position is generated for each servo cycle. However, if there is a large load fluctuation of the mechanism during servo control, a large speed fluctuation occurs accordingly. There was a problem that.

  FIG. 10 is a diagram illustrating an example of a time change between the target position and the detection position.

  As shown in FIG. 10, when a target position that increases by ΔP every given servo cycle (ΔT) is given, if the load on the mechanism of the printing apparatus becomes high at time T = T1, the PWM output signal for servo control becomes the upper limit. The state of value (PWM_MAX) continues. In such a case, the detection position (actual position) cannot follow the target position, and greatly deviates from the target position. After that, when the load is eliminated at time T = T2, the detected speed becomes very high with respect to the target speed in an attempt to recover the position shift. If the detected speed increases, the servo control starts to decelerate to bring the speed closer to the target speed.

  FIG. 11 is a comparison diagram of the target position profile and the detected position profile, and the target speed profile and the detected speed profile. Here, the times T = T1 and T = T2 are the same as those shown in FIG. 10, and are the time when the high load on the mechanism unit starts and the time when the high load is eliminated, respectively.

  As shown in FIG. 11, at time T = T2, when the detection speed is increased in order to eliminate the high load and the delay in position detection, even if deceleration is suddenly started, the correct final target position is obtained. The problem that it cannot stop occurs.

  The present invention has been made in view of the above-described conventional example. A recording apparatus, a sheet feeding apparatus, and a sheet feeding control capable of accurately supplying an object that is servo-controlled to a target position even when a load changes rapidly. It aims to provide a method.

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

  That is, a recording apparatus that performs recording on a recording medium by a recording head, the first roller feeding the recording medium into the recording apparatus from a position where the recording medium is placed, and the first roller A DC motor that supplies a driving force to the encoder, an encoder that detects a rotation amount of the first roller, and a generation unit that generates a target position for feeding the recording medium by the first roller; PWM based on the correction means for correcting the target position generated by the generation means, the target position generated by the generation means or corrected by the correction means, and the rotation amount detected by the encoder A control unit that generates a signal and servo-controls the DC motor based on the PWM signal; and a target generated by the generation unit or modified by the correction unit First comparing means for comparing the position and the amount of rotation detected by the encoder, and correction control means for controlling the correction by the correcting means in accordance with the result of the comparison by the first comparing means. Features.

  According to another aspect of the present invention, there is provided a paper feeding device that conveys a placed recording medium to a predetermined position, and a roller that conveys the recording medium from the position where the recording medium is placed into the device. A DC motor that supplies a driving force to the roller, an encoder that detects a rotation amount of the roller, a generation unit that generates a target position for feeding the recording medium by the roller, and the generation PWM signal based on correction means for correcting the target position generated by the means, target position generated by the generation means or corrected by the correction means, and the rotation amount detected by the encoder And a control means for servo-controlling the DC motor by the PWM signal, and a target position generated by the generation means or corrected by the correction means And a rotation amount detected by the encoder, and a correction control unit that controls to perform correction by the correction unit according to a result of comparison by the comparison unit. Equipment.

  According to still another aspect of the present invention, there is provided a sheet feeding control method for feeding a loaded recording medium by a roller supplied with a driving force by a servo-controlled DC motor, wherein the rotation of the roller is performed using an encoder. A detecting step for detecting the amount, a generating step for generating a target position for feeding the recording medium by the roller, a correcting step for correcting the target position generated in the generating step, and a generating step in the generating step Or a control step of generating a PWM signal based on the target position corrected in the correction step and the rotation amount detected by the encoder, and servo-controlling the DC motor by the PWM signal; The target position generated in the generation step or corrected in the correction step is compared with the rotation amount detected by the encoder. A comparing step of, in accordance with the result of comparison in said comparing step comprises a paper feed control method characterized by a control step of modifying the control to perform the correction in the correction process.

  Therefore, according to the present invention, there is an effect that even if there is a large load fluctuation in servo control, it is possible to accurately supply, for example, a recording medium, which is an object of servo control, to a target position.

  Hereinafter, preferred embodiments of the present invention will be described more specifically and in detail with reference to the accompanying drawings.

  In this specification, “recording” (sometimes referred to as “printing”) does not represent only the case of forming significant information such as characters and graphics. In addition to this, an image, a pattern, a pattern, or the like is widely formed on a recording medium regardless of whether it is significant involuntary, or whether it is manifested so that a human can perceive it visually, or It also represents the case where the medium is processed.

  “Recording medium” refers not only to paper used in general recording apparatuses but also widely to cloth, plastic film, metal plate, glass, ceramics, wood, leather, and the like that can accept ink. Shall.

  Further, “ink” (sometimes referred to as “liquid”) should be interpreted widely as in the definition of “recording (printing)”. That is, by being applied on the recording medium, it is used for forming an image, pattern, pattern, etc., processing the recording medium, or processing the ink (for example, solidification or insolubilization of the colorant in the ink applied to the recording medium). It shall represent a liquid that can be made.

  Furthermore, unless otherwise specified, the “nozzle” collectively refers to an ejection port or a liquid channel communicating with the ejection port and an element that generates energy used for ink ejection.

  FIG. 1 is a side sectional view showing a mechanism portion of a recording apparatus that performs recording using an ink jet recording head according to a typical embodiment of the present invention.

  In FIG. 1, reference numeral 1 denotes a motor which is a driving source for conveying a recording medium such as recording paper, 2 is a conveyance (LF) roller (second roller) for conveying the recording medium, and 3 is a position of the conveyance roller 2. , An encoder mounted coaxially with the conveying roller 2 to detect the speed. Also, 4 is a paper feed roller (first roller) for feeding the recording medium, 5 is a pressure plate for pressing the placed recording medium against the paper feed roller 4, and 8 is a feed roller 2 and paper feed. This is a paper feed lever for connecting the driving of the roller 4. In this embodiment, a DC motor is used as the motor 1. The encoder 3 is a rotary encoder.

  When a carriage (not shown) on which an ink jet recording head (hereinafter referred to as a recording head) is moved and the paper feed lever 8 is pushed, the driving of the transport roller 2 is connected to the paper feed roller 4.

  2 to 3 are side sectional views showing the configuration of the transport mechanism of the recording apparatus shown in FIG.

  In FIG. 2 to FIG. 3, for example, 6 is a separation roller for separating, for example, one recording sheet from a stacked recording sheet.

  When the sheet feeding operation starts, as shown in FIG. 2, the pressure plate 5 is raised and presses the recording sheet against the sheet feeding roller 4, and the sheet feeding roller 4 and the separation roller 6 pinch one sheet. At this time, the load on the transport mechanism unit is increased. When the sheet feeding roller 4 and the separation roller 6 sandwich one sheet of recording paper, the load is further increased when the return lever 13 that moves the other recording sheet back to the pressure plate 5 moves. The magnitude of this load increases as the amount of recording paper returned by the return lever 13 increases. The return lever 13 is arranged away from the paper feed roller 4 in the width direction of the recording paper. When the separated recording sheet is conveyed to the vicinity of the conveying roller 2, the pressure plate 5 is lowered and the sheet feeding roller 4 and the separating roller 6 are separated as shown in FIG. At this time, the load on the transport mechanism is eliminated.

  In this recording apparatus, the load fluctuation of the transport mechanism portion occurs during the period in which the pressure plate 5 and the separation roller 6 are moved up and down as described above. The load generated when the return lever 13 moves as described above varies depending on the amount of recording paper returned by the return lever 13 each time a paper feeding operation is performed.

  FIG. 4 is a block diagram showing a control configuration of the recording apparatus shown in FIGS.

  The transport roller 2 and the paper feed roller 4 rotate using a common motor 1 as a drive source. In this embodiment, the driving force of the motor 1 is transmitted directly to the transport roller 2, but the driving force is transmitted to the paper feed roller 4 via the paper feed lever 8. Accordingly, when the driving force is transmitted by the paper feed lever 8, when the DC motor is driven, both the paper feed roller 4 and the transport roller 2 rotate. On the other hand, when the driving force is not transmitted by the paper feed lever 8, only the transport roller 2 rotates even if the DC motor is driven. The motor 1 can also rotate to convey the recording medium in the direction of arrow A in FIGS. 1 to 3 (this is called forward rotation), and can rotate to convey in the direction opposite to the direction of arrow A. (This is called reverse). The rotation direction of the motor 1 is CPU / G. A. (Gate array) 9 instructs the motor 1 via the motor driver 12. The motor 1 is PWM controlled (described later) via the motor driver 12.

  The entire recording apparatus is CPU / G. A. 9 is controlled based on the control program, various parameters, and speed drive pattern stored in the ROM 11 while using the RAM 10 as a work area for program execution. CPU / G. A. 10 also executes arithmetic processing for PWM control. The RAM 10 is also used as a buffer for storing image data transferred from an external device (not shown) such as a personal computer or a digital camera.

  The output of the encoder 3 is CPU / G. A. 9, the rotation speed of the transport roller 2 and the transport amount by the transport roller are obtained from the output signal from the encoder 3.

  As described with reference to FIG. 1, when the carriage 7 on which the recording head is mounted moves to a predetermined position and the paper feed lever 8 is pushed, the driving force of the motor 1 is also applied to the paper feed roller 4. Communicated. The paper feed lever 8 rises and returns to its original state when the carriage moves to another position.

  FIG. 5 is a block diagram showing a functional configuration of servo control of a motor that drives the transport roller and the paper feed roller.

  In the servo control according to this embodiment, the control program stored in the ROM 11 is stored in the CPU / G. A. 9 and CPU / G. A. 9 is realized by an ASIC (not shown) provided in the inside of the apparatus. Therefore, the components in the area surrounded by the broken line shown in FIG. 5 are functions realized by a program or ASIC. The servo control process is repeatedly performed every servo cycle (ΔT).

  The target position generation unit 501 generates a target position that gradually increases to the final target position (for example, the recording start position of the recording paper) by servo control. On the other hand, the rotation speed and rotation amount of the transport roller 2 are obtained from the output from the encoder 3. These correspond to the conveyance speed of the recording medium and the conveyance position of the recording medium (tip portion), respectively. Since this calculation is publicly known, the description thereof is omitted. In any case, the information on the conveyance speed (rotation speed) and the conveyance position (rotation amount) is shown in FIG. A. 9 is fed back. When the driving force of the DC motor is transmitted to the paper feed roller, the gear ratio of the transmission means provided between the paper feed roller 4 and the transport roller 2 is known in advance. Therefore, from this gear ratio, the rotation amount of the paper feed roller 4 is derived from the rotation amount of the transport roller 2, and the rotation speed of the paper feed roller 4 is derived from the rotation speed of the transport roller 2.

  Therefore, when the control for rotating the paper feed roller 4 is executed, a signal from the encoder 3 provided on the rotating transport roller 2 is used to perform CPU / G. A. The (gate array) 10 can acquire information on the rotation amount and rotation speed of the paper feed roller 4. Thus, CPU / G. A. The (gate array) 10 acquires information indirectly from the encoder 3 provided on the transport roller 2 and controls the rotation of the paper feed roller 4.

  That is, the position information is fed back to the target position from the target position generator 501 in the adder 501a, and the speed information is fed back to the target speed from the differentiation circuit 502 in the adder 502a. This target position is, for example, a rotation amount. The output from the adder 501a is input to the target position delay unit 505 as a position deviation. That is, a deviation between the information on the rotation amount generated by the target position generation unit 501 and the information on the rotation amount obtained from the encoder 3 is obtained, and the deviation is input to the target position delay unit 505.

  The speed corrected by the speed information from the encoder 3 becomes a PWM (pulse width modulation) signal calculated through the PID calculation unit 503 and the PWM generation unit 504, and this is output to the motor driver 12. Further, the PWM signal output from the PWM generation unit 504 is also output to the target position delay unit 505. This PWM signal is represented by a duty value (ratio of high level and low level of pulse signal within a predetermined time, ratio of on and off), and the range of this value is 0% to 100%. The greater the duty value, the greater the power supplied to the motor.

  Therefore, the target position delay unit 505 inputs the PWM signal and the position deviation, and outputs a delay amount (Tdelay) from the ideal detection time of the target position or a deviation amount (Pdelay) from the ideal target position to the target position generation unit 501. To do. The target position generation unit 501 generates a target position at a time delayed by the input delay amount (Tdelay) or generates a target position that is smaller by the input shift amount (Pdelay).

  Next, how the delay amount (Tdelay) and the shift amount (Pdelay) are generated in the target position delay unit will be described with reference to the flowchart and the time change of the detection position and detection speed.

  FIG. 6 is a flowchart showing processing in the target position delay unit that is repeatedly performed every servo cycle (ΔT). This control flow is executed when the paper feed roller is driven.

  FIG. 7 is a diagram showing temporal changes between the detection position and the detection speed, and the ideal target position and the corrected target position. In FIG. 7, a thick solid line indicates an ideal target position, and a thin solid line indicates a corrected target position. The ideal target position is obtained from the target position generation unit 501 when the target position is not corrected according to this embodiment, and shows a profile as shown in FIG.

  First, in step S601, it is checked whether the PWM signal (PWM) output from the PWM generation unit 504 has reached the upper limit (PWM_MAX) that is the maximum output value (second comparison). Note that the upper limit of PWM is 100%. As a result of the comparison, if PWM <PWM_MAX, the process ends as it is, but if PWM = PWM_MAX, the process proceeds to step S602. When PWM <PWM_MAX, even if the target position detection time is delayed, the delay can be easily recovered without large speed fluctuation by performing control to increase the PWM value (duty value). Do not process the example.

  In step S602, it is checked whether the servo control phase is in a constant speed region. If the servo control phase is in the constant speed region, the process proceeds to step S603. If the servo control phase is not in the constant speed region, the process ends. This is because the load fluctuation of the transport mechanism portion occurs in the constant speed region, and the processing of this embodiment is not necessary outside the constant speed region.

  In step S603, it is checked whether or not the difference (D) between the detected position and the (ideal) target position is larger than a predetermined amount (ΔP: threshold value) (first comparison). ΔP is a distance by which the target position increases in the servo cycle (ΔT). FIG. 7 shows the relationship between the difference (D) and the predetermined amount (ΔP). In FIG. 7, for example, D ≦ ΔP at time T = T1 + ΔT.

  As a result of the comparison, if D> ΔP, the process proceeds to step S604. If D ≦ ΔP, the process of this embodiment is terminated. This is because if the difference between the detection position and the target position is within ΔP, the difference can be easily recovered without significant speed fluctuation by servo control.

  Finally, in step S604, ΔT is added to the delay amount (Tdelay) from the ideal detection time (target time) to reach the target position. For example, in FIG. 7, D> ΔP at time T = T1 + 2ΔT. At this time, from the ideal target position, ΔP should be added to the value of the position (P), but the time to perform the addition is delayed by ΔT. According to FIG. 7, the delay amount (Tdelay) at time T = T1 + 2ΔT is Tdelay = ΔT. Although the delay amount (Tdelay) is reset to “0” before the servo control is started, only the addition process is performed during the servo control, and the value is not reset.

  In this manner, the target position generation unit 501 outputs the target position at a timing delayed by Tdelay by the Tdelay output from the target position delay unit 505.

  According to the processing described above, when it is determined that the load on the transport mechanism unit is high and it is difficult to recover the delay of the time for detecting the target position without large speed fluctuation by servo control, the target position The detection time is delayed in time.

  Due to such a delay, for example, when T = T1 + 3ΔT shown in FIG. 7, the difference (D) <ΔP is adjusted.

  In the process shown in FIG. 6, the temporal correction is performed, but the distance itself may be corrected instead of the correction.

  Further, when only the transport roller 2 is driven, the processing as shown in FIG. 6 is not executed. That is, in the configuration shown in FIG. 5, the target position generation unit 501 does not perform a process of inputting a delay amount from the target position delay unit 505 and generating a delay amount (Tdelay) or a shift amount (Pdelay). Servo control is performed based on the target position output from the target position generation unit 501 and the detection position and detection speed obtained from the encoder 3. This is because when the recording medium is conveyed by the conveying roller 2, a large load on the mechanism as shown in FIG. 10 does not occur.

  FIG. 8 is a flowchart showing processing in the target position delay unit that is repeatedly performed every servo cycle (ΔT). In FIG. 8, steps S601 to S603 perform the same processing as in FIG. 6, but in step S604 ′, ΔP is added to the deviation amount (Pdelay) from the ideal target position. Pdelay is reset to “0” before the start of servo control, but only addition processing is performed during servo control, and the value is not reset.

  Pdelay is defined as the difference between the ideal target position and the corrected target position, as shown in FIG. For example, at time T = T1 + 2ΔT shown in FIG. 7, ΔP should be added to the value of position (P) from the ideal target position, but ΔP is not added because D> ΔP. . Therefore, the corrected target position is shifted by ΔP from the ideal target position.

  As described above, the difference between the corrected target position and the detected position is checked every servo control cycle (ΔT), and the deviation amount (Pdelay) is added so that the difference (D) satisfies D <ΔP. Will increase. For example, at time T = T1 + 5ΔT shown in FIG. 7, Pdelay = 3ΔP. Anyway, by such adjustment, D <ΔP again at time T = T1 + 6ΔT.

  According to the embodiment described above, for example, as shown in FIG. 7, even when the load of the transport mechanism unit becomes high at time T = T1 and the PWM signal output of servo control reaches the upper limit value (PWM_MAX), The target position can be corrected in time or position. Thereby, even when the load is subsequently eliminated at time T = T2, the difference between the target position and the detected position is within ΔP.

  For this reason, in order to eliminate this difference, there is no need to increase the rotational speed of the motor and transport the recording medium at a high speed. For this reason, the detection speed by the encoder does not become excessively larger than the target speed.

  FIG. 9 is a diagram showing a comparison between the detection position and the target speed corrected by the detection speed obtained by this embodiment and the target speed.

  As shown in FIG. 9, according to this embodiment, the recording medium can be correctly transported to the final target position even after the load of the transport mechanism is changed.

  As described above, according to this embodiment, although it takes some time to complete the feeding when the recording medium is fed, the recording medium can be accurately conveyed irrespective of the load fluctuation applied to the conveying mechanism at that time. . This makes it possible to accurately position the recording medium at the recording start position.

  As a configuration for transmitting the driving force of the motor 1 to the paper feed roller, the following configuration may be used in addition to the above-described embodiment. That is, when the carriage is moved to a predetermined position, the paper feed lever 8 is slid so that the transmission means is operable (operation permitted), and the driving force of the motor 1 is supplied via the transmission means to the paper feed roller 4. It is the composition to tell to. Further, when the carriage is moved from a predetermined position to another position, the paper feed lever 8 is raised, whereby the transmission means is disabled (prohibited), and the driving force of the motor 1 is transmitted to the paper feed roller 4. Absent.

  When the transmission means is in an operable (permitted operation) state, when the motor 1 is rotated in the reverse direction, the paper feed roller rotates forward via the transmission means and feeds the recording medium from the paper feed tray. The leading edge of the recording medium can be conveyed to a conveying roller that is rotating in the reverse direction.

  In the embodiment described above, the encoder 3 is provided on the transport roller 2. However, as shown in FIG. 12, in addition to the encoder 3 for the transport roller 2, the encoder for the paper feed roller 4 is used. 3a may be provided. In this case, CPU / G. A. 9 may be provided with a function of selecting the signal of either encoder (not shown). With this configuration, the CPU / G. A. 9, the position information and speed information of the encoder 3 can be used to control the driving of the conveying roller 2, while the position information and speed information of the encoder 3a can be used to control the driving of the paper feed roller 4.

  In the above embodiments, the liquid droplets ejected from the recording head are described as ink, and the liquid stored in the ink tank is described as ink. However, the storage is limited to ink. It is not a thing. For example, a treatment liquid discharged to the recording medium may be accommodated in the ink tank in order to improve the fixability and water resistance of the recorded image or to improve the image quality.

  The above embodiment employs a method using a means for generating thermal energy (for example, an electrothermal converter, a laser beam, etc.) as energy used for performing ink discharge, particularly among ink jet recording methods. ing. The thermal energy causes a change in the state of the ink, thereby achieving high recording density and high definition.

1 is a perspective view showing an outline of a configuration of an ink jet recording apparatus which is a typical embodiment of the present invention. , FIG. 2 is a side cross-sectional view illustrating a configuration of a transport mechanism unit of the recording apparatus illustrated in FIG. 1. FIG. 2 is a block diagram illustrating a control configuration of the recording apparatus illustrated in FIG. 1. FIG. 5 is a block diagram illustrating a functional configuration of servo control of a motor that drives a conveyance roller and a paper feed roller. It is a flowchart which shows the process in a target position delay part. It is a figure which shows the time change of a detection position and detection speed, an ideal target position, and a correction target position. It is a flowchart which shows the process in a target position delay part. It is a comparison figure of the correction target position profile and detection position profile which were obtained according to the Example of this invention, and a target speed profile and a correction detection speed profile. It is a figure which shows the example of the time change of a target position and a detection position. It is a comparison figure of a target position profile and a detection position profile, and a target speed profile and a detection speed profile. It is a block diagram which shows the other control structure of a recording device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor 2 Conveyance (LF) roller 3 Encoder 4 Paper feed roller 5 Pressure plate 6 Separation roller 7 Carriage 8 Paper feed lever 9 CPU / G. A.
10 RAM
11 ROM
12 motor driver 501 target position generation unit 502 differentiation circuit 503 PID calculation unit 504 PWM generation unit 505 target position delay unit

Claims (10)

A recording apparatus for recording on a recording medium by a recording head,
A first roller for feeding the recording medium into the recording apparatus from a position where the recording medium is placed;
A DC motor for supplying a driving force to the first roller;
An encoder for detecting a rotation amount of the first roller;
Generating means for generating a target position for feeding the recording medium by the first roller;
Correcting means for correcting the target position generated by the generating means;
A PWM signal is generated based on the target position generated by the generating unit or corrected by the correcting unit and the rotation amount detected by the encoder, and the DC motor is servo-controlled by the PWM signal. Control means;
First comparing means for comparing the target position generated by the generating means or corrected by the correcting means with the rotation amount detected by the encoder;
And a correction control unit configured to control the correction by the correction unit in accordance with a result of the comparison by the first comparison unit.   The correction control means performs correction by the correction means when a difference between the target position obtained by the comparison by the first comparison means and the detected rotation amount is larger than a predetermined threshold value. The recording apparatus according to claim 1, wherein the recording apparatus is controlled. A second comparing means for comparing the PWM signal with a maximum output value of a predetermined PWM signal;
The recording apparatus according to claim 2, wherein the correction control unit further controls the correction unit to perform correction when the PWM signal reaches the maximum output value.   The recording apparatus according to claim 3, wherein the correction control unit further controls the correction unit to perform correction when the rotation of the DC motor is in a constant speed region.   The recording apparatus according to claim 4, wherein the constant speed region is a time when the recording medium is driven by the first roller.   The recording apparatus according to claim 1, wherein the correction by the correction unit is correction of the target position itself, or correction of a target time to reach the target position.   The recording apparatus according to claim 1, wherein the correction unit corrects the target position in a servo cycle of servo control by the control unit. A second roller for conveying the recording medium fed by the first roller to a recording position by the recording head;
The recording apparatus according to claim 1, further comprising another encoder that detects a rotation amount of the second roller. A paper feeding device that conveys a placed recording medium to a predetermined position,
A roller for conveying the recording medium into the apparatus from a position where the recording medium is placed;
A DC motor for supplying a driving force to the roller;
An encoder for detecting the rotation amount of the roller;
Generating means for generating a target position for feeding the recording medium by the roller;
Correcting means for correcting the target position generated by the generating means;
A PWM signal is generated based on the target position generated by the generating unit or corrected by the correcting unit and the rotation amount detected by the encoder, and the DC motor is servo-controlled by the PWM signal. Control means to
Comparison means for comparing the target position generated by the generation means or corrected by the correction means with the rotation amount detected by the encoder;
And a correction control unit configured to control the correction by the correction unit in accordance with a result of the comparison by the comparison unit. A paper feed control method for feeding a loaded recording medium by a roller supplied with a driving force by a servo-controlled DC motor,
A detection step of detecting the rotation amount of the roller using an encoder;
A generating step for generating a target position for feeding the recording medium by the roller;
A correction step of correcting the target position generated in the generation step;
A PWM signal is generated based on the target position generated in the generation step or corrected in the correction step and the rotation amount detected by the encoder, and the DC motor is servo-controlled by the PWM signal. A control process,
A comparison step of comparing the target position generated in the generation step or corrected in the correction step with the rotation amount detected by the encoder;
And a correction control step for controlling the correction in the correction step according to the result of the comparison in the comparison step.

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