JP2007301944A - Printing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To constitute a printing apparatus which properly stops conveyance by a timing when a conveyance amount reaches a target amount, by carrying out deceleration of a servo motor without forcing. <P>SOLUTION: A deceleration processing means 2D is equipped which sets a deceleration initial rotation amount that forms a deceleration tendency larger than an ideal deceleration locus after a deceleration starting position is reached by the rotation of the servo motor M31, and which converges a deviation of the ideal deceleration locus after great deceleration is carried out by supplying a target supply power corresponding to the deceleration initial rotation amount to the servo motor M31. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention includes a conveyance mechanism that conveys a print medium and a servo motor that drives the conveyance mechanism, and sets a target supply power based on a feedback signal from an encoder that measures the rotation amount of the servo motor at each sampling period. The present invention relates to a printing apparatus including a control unit that sets and supplies the target supply power to the servo motor.

  There exists what is described in patent document 1 as a thing similar to the printing apparatus comprised as mentioned above. That is, this Patent Document 1 includes a carriage that is supported so as to be movable in the main scanning direction, and a belt-type conveyance unit that supplies a print medium (paper in the document) to a position below the carriage. Printing is realized by ejecting ink from a recording head formed on the lower side of the carriage with respect to the conveyed print medium.

  Moreover, in this patent document 1, a conveyance part is comprised with the endless belt spanned between the conveyance roller and the tension roller, and it is equipped with the servomotor (subscanning motor in literature) which drives a conveyance roller. A control unit (control unit in the literature) is provided that controls the power supplied to the servo motor in a PWM manner based on a feedback signal from an encoder that acquires the amount of rotation.

  In this Patent Document 1, the control unit detects the feed speed of the conveyor belt by counting the detection pulses of the encoder, detects the amount of movement of the conveyor belt, detects the speed deviation from the target speed, The control value (power value) of the servo motor is obtained by PID control based on the detection result of.

Japanese Patent Laying-Open No. 2005-137075

  Considering a printing apparatus that conveys a print medium by the driving force of a servo motor, as described in Patent Document 1, printing is performed by operating the carriage in the main scanning direction with conveyance of the print medium stopped. Then, every time the carriage reaches the end in the main scanning direction, the print medium is transported by a set amount in the sub scanning direction.

  Increases the servo motor rotation during print medium conveyance, and then starts deceleration before reaching the required conveyance amount and stops the servo motor rotation when the conveyance amount reaches the target amount with high accuracy. There is a need to do.

  In this type of control, ideal speed and amount of rotation during deceleration are set in advance for each sampling period, and after the amount of rotation of the servo motor reaches a value to start deceleration, it is made ideal for each sampling period. The power supplied to the servo motor is also set by PID control or the like so that the speed and the rotation amount can be obtained.

  However, in the case of determining from the sampling signal that the timing for starting deceleration has been reached, after the sampling for determining that the timing for starting deceleration has been reached, the ideal speed and rotation amount are fed back as described above. Since the power supplied to the servo motor is set as described above, there will be a slight delay in the start of deceleration, and even if control is performed with the ideal speed and rotation amount set, the transport amount will be the target amount. The deviation did not converge at the timing reached, and the servo motor rotation could not be stopped at an appropriate position.

  In order to eliminate such an inconvenience, it may be considered to lengthen the time from the start of deceleration to the stop of rotation of the servo motor. However, if the time required for deceleration is increased, the time for transporting the print medium becomes longer, and the time for print processing in the printing apparatus becomes longer, so there is room for improvement.

  An object of the present invention is to rationally configure a printing apparatus that smoothly decelerates a servo motor and appropriately stops conveyance at a timing when the conveyance amount reaches a target amount.

A feature of the present invention includes a transport mechanism that transports a print medium and a servo motor that drives the transport mechanism, and supplies a target based on a feedback signal from an encoder that measures the rotation amount of the servo motor at each sampling period. In a printing apparatus including a control unit that sets power and supplies the target supply power to the servo motor,
The control unit is set with a deceleration start position of the servo motor and an ideal deceleration trajectory that tends to reduce the amount of rotation to be fed back every sampling period after reaching the deceleration start position.
When it is determined from the feedback signal that the deceleration start position has been reached, an initial deceleration amount that causes a deceleration tendency greater than the ideal deceleration locus after reaching the deceleration start position is set. The target supply power corresponding to the rotation amount is supplied to the servo motor, and thereafter, the deviation between the rotation amount of the servo motor indicated by the feedback signal for each sampling period and the rotation amount indicated by the ideal deceleration locus is converged. It is in the point provided with the deceleration process means which performs a process.

  With this configuration, when it is determined from the sampling signal that the deceleration start position has been reached, the deceleration processing means sets an initial deceleration amount that tends to decelerate larger than the ideal deceleration locus, and responds to this initial deceleration amount. The target supply power to be supplied is supplied to the servo motor. After the servo motor is greatly decelerated by this supply, the rotation amount obtained from the feedback signal for each sampling period, the rotation amount based on the ideal deceleration locus, etc. A deviation is obtained, and processing for converging the deviation is performed. In other words, in this control, by performing deceleration that tends to be greater than the deceleration tendency set in the ideal deceleration locus in the early stage of deceleration, it is possible to stop the rotation of the servo motor reliably at a timing that accelerates convergence. It becomes possible. As a result, a printing apparatus has been constructed in which the servo motor is smoothly decelerated and the conveyance is stopped properly when the conveyance amount reaches the target amount.

  According to the present invention, the deceleration start position is set as an integrated value of the rotation amount when the rotation amount is measured with reference to the rotation start position of the servo motor in the ideal deceleration locus. A deceleration initial speed is associated with the rotation amount indicated, and the deceleration processing means obtains the deceleration initial rotation amount based on the deceleration initial speed acquired based on the association after reaching the deceleration start position. Also good.

  With this configuration, when the integrated value of the rotation amount of the servo motor is obtained from the feedback signal and it is determined from this integrated value that the deceleration start position has been reached, the initial deceleration is determined from the initial deceleration speed associated with this deceleration position. The amount of rotation can be obtained.

  In the present invention, the deceleration processing means sets the initial deceleration rotation amount and starts deceleration, and then continues deceleration, so that the speed indicated by the reduced trajectory is lower than the speed indicated by the ideal deceleration trajectory. The process of converging the deviation may be performed after reaching the state.

  With this configuration, control is performed so that the ideal deceleration trajectory is converged from a state where the speed is lower than the speed indicated by the ideal deceleration trajectory. For example, even when deceleration is continued for a time corresponding to one sampling period, overshooting is performed. Is suppressed.

  In the present invention, an ideal control trajectory including an ideal acceleration trajectory for increasing the rotation speed at the start of rotation of the servo motor, an ideal constant velocity trajectory for maintaining the rotation speed, and the ideal deceleration trajectory for reducing the rotation speed is set. In addition, position information to be acquired from the feedback signal and speed information are stored in association with the ideal control trajectory for each sampling period, and the control unit performs PID control based on the feedback signal. May be executed.

  With this configuration, the control unit acquires the rotation amount and rotation speed to be acquired for each ideal sampling period from the ideal rotation locus, and the target supply power by PID control so as to obtain the rotation amount and rotation speed from the feedback signal. Can be set.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
〔overall structure〕
As shown in FIGS. 1 and 2, two magazine accommodating portions A and A are arranged at the bottom of the housing 10, and an ink jet type printing portion B that performs printing by spraying ink is arranged at the top of the housing 10, An ink storage unit C is disposed on the side of the housing 10, and a sorting unit 17 that feeds a relatively small size paper P (an example of a print medium) to the upper surface of the housing 10 with the lateral feed belt 16, and a large size. An ink jet type printing apparatus is configured by arranging a rack plate 18 for receiving the size paper P.

  The two magazine housing portions A and A are provided with a drawer 20 that can be opened and closed by a sliding operation integral with the front wall body 10A, and a magazine 21 can be set in the drawer 20. The magazine 21 has a structure for storing a roll-shaped paper P wound around a core or the like. The print unit B is configured to print an image on the paper P supplied from the magazine housing unit A by spraying ink with the print head H (see FIG. 3). The part is provided with a wall 10B in which a window part 22 made of a transparent resin plate is formed so as to be freely opened and closed.

  In the ink reservoir C, a plurality of ink cartridges 23 having different hues are exchangeably disposed in a wall body 10C that can swing and open around an axial center in a vertically oriented posture. Each ink cartridge 23 encloses black (BK), light black (LK), cyan (C), magenta (M), light cyan (LC), light magenta (LM), and yellow (Y) ink. Seven colors are used. Although not shown in the drawing, this ink jet type printing apparatus feeds the ink enclosed in the ink cartridge 23 by air pressure, temporarily stores it in a sub tank (not shown), and then supplies it to the print head H. An ink supply system is provided.

[Conveyance system configuration]
As shown in FIGS. 3 and 4, the printing apparatus supplies the paper P from the magazine housing section A to the printing section B by the supply unit U1, and the printing section B transports it by the print transport unit U2. However, after this printing, a transport system is provided that cuts the print size by the cutter unit U3, and then transports it from the switchback unit U4 by the discharge unit U5.

  The supply unit U1 includes a support roller 25 that applies a rotational force to the roll-shaped paper P accommodated in the two magazine accommodating portions A and A, and a pressure-type supply roller 26 that conveys the paper P from the magazine 21. The paper P is fed into the print transport unit U2 in a form guided by the guide member 27. Although not shown in the drawing, the support roller 25 and the supply roller 26 are driven by an electric motor for supply and conveyance.

  The print transport unit U2 includes a pressure-bonded first transport roller 31 disposed on the upstream side of the print head H and a pressure-bonded second transport roller 32 disposed on the downstream side of the print head H. And a guide plate 33 for guiding the back side of the paper P at an intermediate position between the first and second transport rollers 31 and 32 (the transport mechanism of the present invention). Below the guide plate 33, a casing 34 that applies negative pressure to the paper P through a large number of through holes formed in the guide plate 33, and the air inside the casing 34 is exhausted to be negative. And a fan 35 for generating pressure.

  The first transport roller 31 includes a driven roller 31A for transporting the paper P by pressure. A drive shaft 31S of the first transport roller 31 is connected to an output shaft (not shown) of a servo motor M31 for sub-scanning. Power is transmitted through a gear-type reduction mechanism. The second conveying roller 32 includes a driven roller 32A for pressure-conveying the paper P, and the driving shaft 32S of the second conveying roller 32 and the driving shaft 31S of the first conveying roller 31 are operated in synchronization. As described above, the belt interlocking mechanism in which the endless belt 36 is wound around the sprockets 36S and 36S provided on the respective drive shafts 31S and 32S is provided. The servo motor M31 is configured as a direct current type (DC type), and an end portion of the servo motor M31 is provided with an encoder E31 for feeding back the rotation amount of the output shaft.

  In the printing apparatus of the present invention, it is assumed that the encoder E31 outputs a one-pulse signal when the output shaft of the servo motor M31 makes one rotation. However, when the output shaft of the servo motor M31 makes one rotation. Alternatively, a device that outputs a plurality of pulses may be used. Further, an AC type (AC type) servo motor M31 may be used, and a transport belt may be used as the transport mechanism.

  As shown in FIG. 4, a carriage 39 is supported by a slider 38 guided by a guide rail 37 arranged in a posture along the main scanning direction (the width direction of the paper P), and the print head is disposed on the lower surface side of the carriage 39. Supports H. A timing belt type driving belt 41 is wound around a pair of pulleys 40 arranged in the vicinity of both ends of the guide rail 37, and a main scanning servo motor M 40 for driving one pulley 40 is provided. By fixing the carriage 39, the print head H is configured to reciprocate integrally with the carriage 39 by the rotational driving force of the pulley 40.

  The servo motor M40 for main scanning is configured as a DC type (DC type) like the servo motor M31, and an encoder E40 for feeding back the rotation amount is provided on the output shaft of the servo motor M40. .

  With such a configuration, when an image is printed on the paper P, the first and second transport rollers 31 and 32 are synchronously driven by the servo motor M31 to supply the paper P to the printing position, and the guide plate 33 is negatively fed. By applying the pressure, the carriage 39 is operated in one direction along the main scanning direction in a state where the paper P is attracted to the guide plate 33 and the planar accuracy of the paper P is increased, so that (in the main scanning direction) In conjunction with this operation, an image is printed with a print width set by ejecting ink from the print head H onto the paper P in conjunction with this operation.

  By starting printing in this way, after the carriage 39 reaches the operating end, the first and second transport rollers 31 and 32 are synchronously driven by the servo motor M31 by the servo motor M31, so that the print width is reached. The paper P is transported by a corresponding unit transport amount, and thereafter, the carriage 39 is operated in the other direction (reverse direction) along the main scanning direction, and a printing operation with a print width is performed in conjunction with this operation. By repeating this printing operation, an image is printed on the paper P. When printing is performed in this way, the sub-scanning servo motor M31 controls the conveyance of the paper P by the print width described above. Done.

  The servo motor M31 is used not only when the paper P is fed to the printing position but also when returning the paper P to the magazine accommodating portion A. When the paper P is thus transported, As described later, the rotation is controlled by PID control in a state where the speed to be set and the target rotation speed are set.

  3 and 4, the cutter unit U3 includes a fixed blade 45 fixed to a frame (not shown), a movable blade 46, a cutter motor M46 for driving the movable blade 46, and the cutter. A crank-type drive mechanism 47 that converts the rotational driving force from the motor M46 into a reciprocating operating force, and a crimp-type discharge roller 48 that conveys the paper P that has passed through the cutting position of the cutter unit U3. A discharge motor M48 for driving the discharge roller 48 is provided.

  The switchback unit U4 includes a driving roller 50, an idle-type reversing roller 51 disposed at a position where it is crimped to the driving roller 50, a driving motor that rotates the driving roller 50, although not shown in the drawing, and a reversing function. A reversing mechanism that operates the roller 51 around the axis of the driving roller 50 in both forward and reverse directions by 90 degrees. In this switchback unit U4, the paper P fed from the front end side by being transported by the discharge roller 48 is further transported in a state where it is pressure-bonded by the driving roller 50 and the reverse roller 51, and as indicated by an arrow in FIG. In addition, after the reversing roller 51 is rotated 90 degrees around the axis of the driving roller 50, the driving roller 50 is reversed to perform the operation of feeding the paper P from the rear end side to the discharge unit U5. It is configured to reverse the front and back.

  The discharge unit U5 includes a plurality of pressure rollers 55 for transporting the paper P, and a path for feeding the paper P transported by the pressure rollers 55 to either the lateral feed belt 16 or the rack plate 18 at the top of the housing. A switching mechanism (not shown) is provided.

[Control system configuration]
This printing apparatus includes a control unit 1 that manages printing. In this control unit 1, an outline of a control system that mainly transports paper P can be shown as shown in FIG.

  That is, the control unit 1 supplies power to the sub-scanning servo motor M31 via the driver D, and acquires the rotation amount by a signal from the encoder E31 of the servo motor M31. Further, electric power is supplied to the servo motor M40 for main scanning via the driver D, and the rotation amount is acquired by a signal from the encoder E40 of the servo motor M40. Similarly, the control unit 1 supplies power to the cutter motor M46 via the driver D, supplies power to the discharge motor M48 via the driver D, and controls the print head H via the driver D. Although a servo motor can be used for the cutter motor M46 and the discharge motor M48, the structure and control form of the motor are omitted because they are not directly related to the gist of the invention.

  An outline of a control system for transporting the paper P in the control unit 1 is shown in FIG. This control system includes a trajectory calculation unit 2, a PID control unit 3, and a PWM power supply unit 4. The control signals are transmitted in this order, and the supply power signal generated by the PWM power supply unit 4 is output to the driver D. The electric power from the driver D is supplied to the servo motor M31 for driving. Further, the signal of the encoder E31 of the servo motor M31 is fed back to the trajectory calculation unit 2, and the timing signal from the timing signal generation unit 5 is sent to the PWM power supply unit 4 and the trajectory calculation unit 2. A signal system is provided.

  The trajectory calculation unit 2 obtains trajectory information from the trajectory table Ta and sets processing, acceleration processing means 2B that performs control during acceleration of the servo motor M31, and acceleration processing means 2B. The constant speed processing means 2C for performing control to rotate the servo motor M31 at a constant speed after the control, the deceleration processing means 2D for controlling the deceleration of the servo motor M31 after the control by the constant speed processing means 2C, and the encoder E32 And a counter 2E that counts and supplies the signal to the processing setting means 2A.

  The PWM power supply unit 4 outputs a pulse signal at a set time interval, and supplies the pulse signal by setting a ratio (duty ratio / duty cycle) between the period in which the pulse signal is output and the ON time of the pulse signal. It functions to freely set the power to be used.

  In this control unit 1, the locus calculation unit 2, the PID control unit 3, and the PWM power supply unit 4 are configured with hardware circuits, or configured with software, or hardware and software, It is possible to comprise by the combination of.

[Control form-transport control]
The outline of the conveyance control in which the control unit 1 controls the servo motor M31 to convey the paper P can be shown as a flowchart in FIG. 7, and when the paper P is conveyed in this way, the servo motor M31 is conveyed. The ideal control trajectory X acquired from the trajectory table Ta so as to set a target rotation amount (which can be regarded as a target rotation speed) for each sampling period can be shown as a graph in FIG.

  The ideal control trajectory X includes an ideal acceleration trajectory Xa formed in an acceleration region that increases the rotation speed of the servo motor M31, an ideal acceleration formed in a constant velocity region that maintains the rotation speed after acceleration in the acceleration region, and the like. A speed trajectory Xb and an ideal deceleration trajectory Xc formed in a deceleration region for reducing the rotational speed after the rotational speed in the constant speed region is maintained are provided.

  In the ideal control locus X, the absolute values of the acceleration in the acceleration region (ideal acceleration locus Xa) and the negative acceleration in the deceleration region (ideal deceleration locus Xc) are made equal. In this ideal control trajectory X, the horizontal axis is set as the time axis, and this horizontal axis corresponds to the rotation amount (count value) fed back from the encoder E31, and every horizontal sampling period. Information necessary for control is associated.

  Specifically, the count value of the end portion on the start side of the ideal acceleration locus Xa is set to “0”, and the count value of the end portion on the end side of the ideal deceleration locus Xc is related to this end portion. This value is set to a value necessary for the conveyance of the image and is associated with this end portion. From such association, the rotation amount (total integrated value of count values) to be fed back from the encoder E31 between the start and stop of the rotation of the servo motor M31 is determined from the count value at the end portion on the end side of the ideal deceleration locus Xc. It is possible to obtain.

  The sampling period T (see FIG. 11) coincides with the time length of the period of the pulse signal generated by the timing signal generator 9, and the counter 2E counts the amount of rotation fed back from the encoder E31 for sampling. This is given to the locus calculation unit 2 every period T.

  As shown in the flowchart of FIG. 7, first, an ideal control locus X is set (step # 01). The ideal control trajectory X is acquired by the trajectory calculation unit 2 from the trajectory table Ta according to the transport amount of the paper P.

  Next, acceleration control is executed after the operation is started, and position information and speed information referred to in deceleration control are calculated and stored when the acceleration control is continued (steps # 02 to # 04). After the rotational speed of the servo motor M31 reaches a target value by this acceleration control, the acceleration control is terminated and the process proceeds to constant speed control (steps # 05 and # 06), and this constant speed control is set. The constant speed control is terminated at the timing when the predetermined time has passed (the sheet has been transported for the set distance), and the process proceeds to the deceleration control. After this deceleration control, the rotation of the servo motor M31 is stopped (# 07, # 100, # Step 08).

  When performing these controls, the rotation speed of the servo motor M31 and the transport position (corresponding to the rotation amount) of the paper P are acquired every sampling period T, and these are associated with the ideal control locus X. A deviation between the rotation speed and the conveyance position speed is obtained, and a target supply power value (target supply power value) supplied to the servo motor M31 is set based on PID control by the PID control unit 3, and the PWM power supply The unit 4 supplies the target supply power to the servo motor M31.

[Details of control]
In the control shown in the flowchart, the “control variable” shown in FIG. 12 is used. This “control variable” is associated with the ideal control trajectory X, and in the acceleration region, by using the variable shown in “calculation in the acceleration region” shown in FIG. The target position and the next target speed (distance to be reached until the next sampling) at the sampling time (n) are set, and control is executed in such a manner that each variable is referred to for each sampling and calculation is performed. Similarly, in the constant speed region, the next target position in the sampling time (n) and the next time in the sampling time (n) are obtained by using what is shown in “calculation in the constant speed region” shown in FIG. The target speed is set, and the control is executed in such a manner that each variable is referred to for each sampling and calculation is performed.

  A speed value as a control variable, for example, V (n) or LV (n) is a numerical value counted by the counter 2E when the servo motor M31 rotates at the speed in the sampling period T, and ideal control. The deviation is obtained by associating with the expected value based on the locus X. Therefore, as indicated by V (n) · T in “calculation in the acceleration region” and “calculation in the constant velocity region” in FIG. In this control, the numerical value can be handled as the speed value without performing the calculation of multiplying the speed value by the time corresponding to the sampling period T. This speed value and position value can be handled in the same dimension.

  Further, in the deceleration area, by using the variables shown in “Calculation in the deceleration area” in FIG. 12, the next target position at the sampling time (n) and the next target speed at the sampling time (n) as described above. Is set, and the basic control form is set so that the control is executed in a form in which calculation is performed by referring to each variable for each sampling. Is done first.

  Further, this control can be shown as shown in the flowchart of FIG. 9, and the process of setting the initial deceleration variable that is set at the initial stage of the control in this deceleration region can be shown as shown in the schematic diagram of FIG. Is possible. Note that the initial deceleration variable set at the initial stage of deceleration is obtained by calculation in step # 04 of the above-described flow chart of conveyance control (see FIG. 7).

  In the above-described step # 04, as shown in FIG. 10, DP (k−1) and DP (k−) indicating the deceleration position for each sampling period T with reference to the deceleration start position DP (k) as the deceleration variable string Q1. 2)... Are set, LP (k), LP (k−1)... Are set as reference variable strings Q2 to be referred to after the start of deceleration, and target positions P (n−2), P are set as target variable strings Q3. (N-1), P (n), P (n + 1)... Are set. The deceleration start position DP (k) is set as an integrated value of the rotation amount with reference to the rotation start position of the servo motor M31.

  In the figure, the count number is shown in the horizontal direction, and the distance between the deceleration positions of DP (k), DP (k-1), DP (k-2). The speeds V (k), V (k−1), and V (k−2) to be set for each sampling period T at the time are associated with each other.

  Similarly, the intermediate distance between the reference positions of LP (k) and LP (k−1) in the reference variable string Q2 is made to correspond to the speeds LV (k) and LV (k−1), and the target variable string Speeds V (n-1) and V (n) that are set to target distances between the target positions of P (n-2), P (n-1), P (n), and P (n + 1) of Q3. , V (n + 1).

  By setting the variable sequence in this way, in constant speed control (control by the constant speed processing means 2C), control is performed so that the target position set in the target variable sequence Q3 is reached every sampling period T. When it is determined at the time of control that the deceleration start position DP (k) has been reached from the count value of the counter 2E and the expected value based on the ideal control locus X, the deceleration control means 2D determines that the reference variable string The first target position P (n) for starting deceleration is set from the reference speed LV (k) between LP (k) and LP (k-1) of Q2 (which coincides with the initial deceleration amount of the present invention). Next, the deceleration initial variable string Q4 for setting the next target position P (n + 1) is set based on the speed obtained from the equation [LV (k) -Acc + α (n)]. The equation [LV (k) −Acc + α (n)] subtracts the set acceleration <Acc> from the speed <LV (k)> that is referred to after the start of deceleration, as shown in FIG. The value <α (n)> for dispersing the adjustment amount is added.

  That is, control according to the ideal constant velocity trajectory Xb is performed so as to reach the target position set in the target variable string Q3 every sampling period T (control by the constant velocity processing means 2C), and the deceleration start position is determined from the feedback signal during this control. If it is determined that DP (k) has been reached, the deceleration control means 2D obtains the deceleration initial speed LV (k) from the reference variable string Q2, and obtains the deceleration initial rotation amount from this value, From this, the target position P (n) is set. After setting the target position P (n) in this way, based on the information fed back immediately before and the information on the target position P (n), PID control by the PID control unit 3 is executed, The PWM power supply unit 4 outputs the supplied power to the servo motor M31 (Steps # 101 and # 102).

  By performing the control of this step, the supply power supplied to the servo motor M31 is lower than the supply power before reaching the deceleration start position DP (k), or supplies the power to reverse the servo motor M31. Thus, based on the straight line drawn by the ideal deceleration trajectory Xc of the ideal control trajectory X, the deceleration straight line R created by performing this step control can be shown as shown in FIG. As can be seen from the figure, the deceleration tendency of the deceleration straight line R is larger than the ideal deceleration locus Xc. In addition, the conveyance speed changes at the time of deceleration, but the conveyance amount does not change. Therefore, as shown in the drawing, the area formed above the ideal deceleration locus Xc by the deceleration straight line R at the start of deceleration, and thereafter the deceleration straight line R As a result, the area formed below the ideal deceleration locus Xc becomes equal.

  In this initial control of deceleration, the initial deceleration speed LV (k) is obtained from the reference variable string Q2, and the target position P (n) is set from this speed. However, the present invention is not limited to this control mode. It is possible to set the target position P (n) from a preset speed in the initial stage of deceleration, or obtain the speed based on a preset negative acceleration, and set the target position P (n) from this speed. It is. Furthermore, the initial deceleration speed or the target position immediately after deceleration may be calculated by calculation.

  When the next feedback signal is acquired after the sampling period T in the initial deceleration initial control has elapsed, the next target position P (n + 1) is set (steps # 103 and # 104). In this way, when the next target position P (n + 1) is set, the set numerical value α (n) is added to which the negative acceleration Acc set from the reference speed LV (k) after the start of the preset deceleration is added. ) Is added (LV (k) −Acc + α (n)).

  After setting the next target position P (n + 1) in this way, the PID control by the PID control unit 3 is executed based on the information of the previous feedback and the information of the next target position P (n), and the supply Electric power is output (# 105 step).

  By performing the control of this step, the supply power supplied to the servo motor M31 is lower than the supply power before reaching the immediately preceding target position P (n), or the power for reversing the servo motor M31 is supplied. Thus, the speed created in this way exists on the extension of the deceleration straight line R.

  The target variable string Q3 indicates the target position and speed in the deceleration control on the ideal deceleration locus Xc. When the next feedback signal is acquired after the sampling period T has elapsed, the target variable sequence Q3 converges on the ideal deceleration locus Xc. As described above, the target position existing at the position of the next sampling timing is set from the target variable string Q3, and the PID control unit 3 is based on the immediately preceding feedback information and the target position information thus set. The PID control according to the above is executed, and the control for outputting the supplied power is repeatedly executed until reaching the position where the rotation of the servo motor M31 is stopped (steps # 106 to # 109).

  In this control, after reaching the deceleration start position DP (k), a control that causes a deceleration tendency greater than that of the ideal deceleration locus Xc is executed for a time corresponding to two sampling periods T, and then the ideal deceleration locus Xc is reached. Although the control has shifted to the convergent control, the control that tends to decelerate more than the decelerating tendency by the ideal deceleration locus Xc may be performed so as to be performed three times or more of the sampling period T.

  As described above, in the present invention, after determining that the deceleration start position DP (k) has been reached from the count value, when the vehicle first decelerates, the initial deceleration speed LV (k) acquired in advance is calculated. By first setting a target position P (n) as a target, it is possible to perform a large deceleration in the early stage of deceleration compared to the case where the deviation from the ideal deceleration locus Xc is obtained and the deceleration is performed. To control the deviation from the ideal deceleration trajectory Xc after the vehicle is greatly decelerated, the convergence is accelerated, the inconvenience of overshooting is eliminated, and the control of the paper P is performed with high accuracy. This makes it possible to improve the print quality.

Perspective view of printing device Perspective view of printing apparatus with part of housing opened Diagram showing the outline of the paper transport path The perspective view which shows the paper conveyance structure of a print conveyance unit Block circuit diagram showing control configuration Block circuit diagram showing the control configuration of the control unit Flow chart of transport control Graphic of control trajectory Deceleration control flowchart Schematic diagram showing information set at the start of deceleration Diagram showing the trajectory at the start of deceleration Diagram that lists variables used during control Diagram that lists variables used during control Diagram that lists variables used during control

Explanation of symbols

1 Control unit 2D Deceleration processing means 31 Conveying mechanism (first conveying roller)
E31 Encoder M31 Servo motor T Sampling period DP (k) Deceleration start position Xa Ideal acceleration locus Xb Ideal constant velocity locus Xc Ideal deceleration locus

Claims (4)

A conveyance mechanism that conveys the print medium and a servo motor that drives the conveyance mechanism, and sets a target supply power based on a feedback signal from an encoder that measures the rotation amount of the servo motor at each sampling period. A printing apparatus comprising a control unit for supplying a target supply power to the servo motor,
The control unit is set with a deceleration start position of the servo motor and an ideal deceleration trajectory that tends to reduce the amount of rotation to be fed back every sampling period after reaching the deceleration start position.
When it is determined from the feedback signal that the deceleration start position has been reached, an initial deceleration amount that causes a deceleration tendency greater than the ideal deceleration locus after reaching the deceleration start position is set. The target supply power corresponding to the rotation amount is supplied to the servo motor, and thereafter, the deviation between the rotation amount of the servo motor indicated by the feedback signal for each sampling period and the rotation amount indicated by the ideal deceleration locus is converged. A printing apparatus comprising deceleration processing means for performing processing.   The deceleration start position is set as an integrated value of the rotation amount when the rotation amount is measured with reference to the rotation start position of the servo motor in the ideal deceleration locus, and the rotation amount indicating the deceleration start position is set. The deceleration initial speed is associated with the deceleration correspondingly, and the deceleration processing means obtains the deceleration initial rotation amount based on the deceleration initial speed acquired based on the association after reaching the deceleration start position. Printing device.   The deceleration processing means sets the initial deceleration rotation amount and starts deceleration, and then continues deceleration to reach a state where the speed indicated by the reduced trajectory is lower than the speed indicated by the ideal deceleration trajectory. The printing apparatus according to claim 1, wherein a process for converging the deviation is performed.   An ideal control locus including an ideal acceleration locus that increases the rotation speed at the start of rotation of the servo motor, an ideal constant velocity locus that maintains the rotation speed, and the ideal deceleration locus that reduces the rotation speed is set. The position information to be acquired from the feedback signal and the speed information are stored in association with the ideal control locus for each sampling period, and the control unit performs PID control based on the feedback signal. Item 4. The printing apparatus according to any one of Items 1 to 3.

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