JP2012148878A - Conveyance device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a time required from a conveyance start up to conveyance completion without deteriorating conveyance accuracy.SOLUTION: A conveyance device includes: (A) a conveyance mechanism that conveys a medium; and (B) a control part that elongates a time required for a deceleration operation in comparison with a time required for an acceleration operation from the start of conveyance up to the stop of the conveyance of the medium regarding the acceleration operation, an operation when the conveyance mechanism starts the conveyance of the medium and accelerates the conveyance speed of the medium and the deceleration operation, an operation when the conveyance mechanism decelerates the deceleration speed of the medium and stops conveyance of the medium. The control part makes the conveyance mechanism perform the acceleration operation until the deceleration operation is started.

Description

  The present invention relates to a transport apparatus and a transport method.

A transport device that transports a medium in a predetermined direction is known. In such a transport apparatus, a highly accurate transport operation may be required. For example, in a transport device used to transport printing paper in a printer, it is necessary to accurately control the transport amount of the printing paper in order to prevent printing misalignment and the like. In particular, in order to realize accurate conveyance, the medium to be conveyed must be accurately stopped at a target stop position. That is, the accuracy of the operation during deceleration when stopping the medium being transported is important.

On the other hand, in the deceleration operation during medium conveyance, a technique for accurately stopping the medium at the target stop position by increasing the deceleration acceleration immediately after the start of deceleration and decreasing the deceleration acceleration immediately before the stop is proposed. (For example, Patent Document 1).

JP 2006-262571 A

According to the transport method of Patent Document 1, even when the medium is transported at a high speed, the deceleration acceleration is reduced immediately before the transport is stopped. The medium can be accurately stopped at the target stop position.

However, in such a method, the conveyance speed is slowly decelerated at the time of deceleration, so that it takes a longer time to start after decelerating. That is, the entire transport time required from the start of the transport of the medium to the end of the transport becomes longer, resulting in a problem that the throughput of the transport device is reduced. In the present invention, the transport device reduces the transport accuracy. The purpose is to shorten the time required from the start of conveyance to the end of conveyance.

The main invention for achieving the above object is (A) a transport mechanism for transporting a medium, and (B) an operation when the transport mechanism starts transporting the medium and accelerates the transport speed of the medium. For the acceleration operation and the deceleration operation that is the operation when the transport mechanism decelerates the transport speed of the medium and stops the transport of the medium, from the start of transport of the medium to the stop of transport of the medium, A control unit that makes the time required for the deceleration operation longer than the time required for the acceleration operation;
The control device causes the transport mechanism to perform the acceleration operation until the deceleration operation is started.

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

FIG. 3 is a diagram illustrating a configuration of a transport device 10. FIG. 4 is a diagram illustrating a relationship between a drive system using a DC motor and a control system in the transport apparatus 10. It is a figure explaining the speed profile of the conveyance speed used at the time of the conventional medium conveyance operation | movement. It is a figure which shows the speed profile of the conveyance speed in the comparative example 2. It is a figure which shows the speed profile of the conveyance speed in 1st Embodiment. It is a figure which shows the speed profile of the conveyance speed in the modification of 1st Embodiment. It is a figure which shows the example of the pattern of the profile for deceleration set beforehand in 2nd Embodiment.

At least the following matters will become clear from the description of the present specification and the accompanying drawings.
(A) a transport mechanism that transports the medium, (B) an acceleration operation that is an operation when the transport mechanism starts transporting the medium and accelerates the transport speed of the medium, and the transport mechanism is the medium About the deceleration operation that is an operation when the conveyance speed of the medium is decelerated and the conveyance of the medium is stopped, the deceleration operation is performed more than the time required for the acceleration operation between the medium conveyance start and the medium conveyance stop. A control unit that increases the time required for the control unit, wherein the control unit causes the transport mechanism to perform the acceleration operation until the deceleration operation is started. .
According to such a transfer apparatus, the time required from the start of transfer to the end of transfer can be shortened without reducing the transfer accuracy.

In such a transport apparatus, it is desirable that the deceleration decreases as time elapses when performing the deceleration operation.
According to such a conveying apparatus, in the deceleration operation at the time of conveying the medium. Since the conveyance speed can be reduced as it is just before the stop, the medium conveyance accuracy can be further improved.

In this transport apparatus, the deceleration operation includes a first deceleration operation and a second deceleration operation. In the first deceleration operation, when the transition from the acceleration operation is performed, the deceleration operation is performed at a predetermined deceleration. Done
In the second deceleration operation, it is desirable to perform the deceleration operation at a larger deceleration than the predetermined deceleration operation when shifting from the first deceleration operation.
According to such a transport apparatus, even when the acceleration is large, the speed fluctuation at the time of shifting to the deceleration operation can be reduced, so that the speed control can be easily performed and the transport precision of the medium can be improved.

In this transport apparatus, the control unit has a plurality of speed profiles that define the deceleration operation, and the control unit includes a plurality of speed profiles according to conditions when the transport mechanism performs the acceleration operation. It is preferable that an optimum speed profile is selected from among them, and the transport mechanism is caused to perform the deceleration operation based on the selected speed profile.
According to such a transport apparatus, an optimum deceleration operation can be executed in accordance with an actual acceleration operation, so that more accurate medium transport can be performed in a short transport time.

In this transport apparatus, the control unit may include a plurality of speed profiles according to a time from the start of transport to a predetermined transport speed when the transport mechanism performs the acceleration operation. It is preferable that an optimal speed profile is selected from the above and the transport mechanism performs the deceleration operation based on the selected speed profile.
According to such a transport apparatus, the optimum deceleration operation can be executed based on the actual acceleration time, so that more accurate medium transport can be performed in a short transport time.

(A) transporting the medium by the transport mechanism; (B) accelerating operation that is an operation when the transport mechanism starts transporting the medium and accelerates the transport speed of the medium; and the transport About the deceleration operation, which is the operation when the mechanism decelerates the medium conveyance speed to stop the medium conveyance, from the time required for the acceleration operation between the medium conveyance start and the medium conveyance stop. In addition, it becomes clear that the control method for increasing the time required for the deceleration operation has the controller cause the transport mechanism to perform the acceleration operation until the deceleration operation is started.

=== Basic Configuration of Conveying Device ===
The conveyance device 10 and its driving method used in this embodiment will be described. The transport apparatus 10 of the present embodiment is a transport apparatus that can transport a transported medium such as paper or a thin plate in a predetermined direction (hereinafter also referred to as a transport direction).
Hereinafter, in this specification, the transport direction is defined as the X direction, and the direction orthogonal to the transport direction (also referred to as the medium width direction) is defined as the Y direction.

<About the structure of the conveying apparatus 10>
FIG. 1 is a schematic diagram illustrating the configuration of a transport apparatus 10 according to the present embodiment. FIG. 2 is a diagram illustrating a relationship between a drive system using a DC motor in the transport apparatus 10 and a control system.
The transport apparatus 10 includes a medium transport mechanism 30 and a controller 60.

The medium transport mechanism 30 transports the medium in the transport direction. The medium transport mechanism 30 is a transport roller pair 3
1, a gear train 32, a PF motor 33, and a rotation detector 34.

The conveyance roller pair 31 includes a conveyance roller 31a and a driven roller 31b, and a medium to be conveyed (for example, paper P) can be sandwiched between them. In addition, although the medium is transported by rotating the roller in the medium transport mechanism 30 in the transport apparatus 10 of the present embodiment, the transport method of the medium transport mechanism 30 is not limited to the method using the roller.
A conveyance method using a belt may be used.

The PF motor 33 applies a driving force (rotational force) to the transport roller 31a via the gear wheel train 32 (FIG. 2). That is, the PF motor 33 is connected to the transport roller 31.
This corresponds to a driving unit that applies a driving force for rotating a. The rotation direction of the PF motor 33 can be freely changed. In the following, the PF motor 33 for feeding the medium in the transport direction
The direction of rotation is referred to as the forward rotation direction, and the reverse rotation is referred to as the reverse rotation direction. In the transport apparatus 10 of the present embodiment, the medium can be transported in the direction opposite to the transport direction by rotating the PF motor 33 in the reverse direction. The drive unit that drives the transport roller 31a is not limited to a “motor” such as the PF motor 33, and an actuator or the like that is operated by hydraulic pressure may be used.

The rotation detector 34 detects the rotation speed and rotation position of the PF motor 33 or the transport roller 31a. Thereby, it is possible to monitor and control the transport amount and transport direction of the medium. In the present embodiment, a rotary encoder is used as the rotation detection unit 34. The rotation detector 34 (rotary encoder) includes a disk scale 34a and a rotary sensor 34b. The disk-shaped scale 34 a has a light-transmitting part that transmits light and a light-shielding part that blocks light transmission at regular intervals along the circumferential direction, and is on the output shaft of the PF motor 33. It is provided and rotates in synchronization with the PF motor 33. The rotary sensor 34b includes a light emitting element (not shown), a light receiving element (not shown) and a signal processing circuit as main components, and detects the current rotation speed and rotation position of the disc scale 34a (PF motor 33). The output signal Sen is transmitted to the controller 60. The rotation detection unit 34 is connected to the transport roller 31.
It may be provided on the rotational axis a, and the rotational speed and rotational position of the transport roller 31a may be directly detected.

The medium transport mechanism 30 may include a plurality of roller pairs similar to the transport roller pair 31. For example, as illustrated in FIG. 1, a discharge roller pair 35 for discharging the medium after conveyance to the outside of the conveyance device 10 may be provided on the downstream side in the conveyance direction of the conveyance roller pair 31. The discharge roller pair 35 has the same configuration as the transport roller pair 31, and discharges the medium by rotating in accordance with the rotation of the transport roller 31a. The discharge roller pair 35 also includes a motor serving as a drive unit, a gear train that transmits drive force, and a rotation detection unit (all not shown).

In the transport device 10, it is also possible to perform some work on the transported medium in the region between the transport roller pair 31 and the discharge roller pair 35. For example, in this region, printing can be performed by ejecting ink onto the medium, and the size and thickness of the medium can be measured by laser measurement.

On the upstream side in the transport direction of the medium transport mechanism 30, a medium supply unit that supplies the medium to the position of the transport mechanism 30, a medium that is supported when the medium is supplied, and a position in the width direction (Y direction) of the medium during transport A medium support unit or the like for adjusting the image may be provided. Further, a discharge tray (not shown) that supports the medium when discharging the medium after conveyance may be provided on the downstream side of the medium conveyance mechanism 30 in the conveyance direction.

The controller 60 is a control unit that controls the rotation speed and rotation direction of the transport roller 31a and the paper discharge roller 35a to transport the medium. As shown in FIG. 2, the controller 60 includes a CPU 61, a ROM 62, a RAM 63, a PROM 64, an ASIC 65, a motor driver 66, and the like, which are connected to each other via a transmission path 67 such as a bus. The controller 60 is connected to the computer COM. The PF motor 33 and the like are controlled by cooperation of these hardware and software and / or data stored in the ROM 62 or PROM 64, or by adding a circuit or a component for performing specific processing. .

=== Comparative Example ===
<Comparative Example 1>
As a comparative example 1, a control method in the case where the transport speed is controlled by a conventional method when a medium is transported using the transport device 10 will be described.

<Conveying speed during medium conveyance>
FIG. 3 is a diagram for explaining a speed profile of the transport speed used in the conventional medium transport operation. In FIG. 3, the vertical axis represents the conveyance speed during medium conveyance, and the horizontal axis represents the time required for medium conveyance (conveyance time).

The transport speed profile (FIG. 3) represents the relationship of the transport speed with respect to the transport time of the medium transport operation in the acceleration region, the constant speed region, and the deceleration region. In the acceleration region, after the transport mechanism 30 starts transporting the stopped medium, an acceleration operation that is an operation for accelerating the medium transport speed to a predetermined speed Vcc is performed. In the constant speed range, a constant speed operation, which is an operation of transporting the medium at a constant speed Vcc, is performed. In the deceleration region, a deceleration operation is performed, which is an operation performed when the transport mechanism 30 decelerates the transport speed of the medium transported at the transport speed Vcc and stops the transport of the medium.

In the acceleration region, the larger the upward slope, the greater the acceleration. In the deceleration region, the greater the downward slope, the greater the deceleration. Parameters that define the transport speed profile include an acceleration time Tacc that represents the time required for the acceleration operation, a constant speed transport time Tc that represents the time required for the constant speed transport operation, a deceleration time Tbcc that represents the time required for the deceleration operation, and A conveyance speed profile table consisting of the conveyance speed Vcc is recorded in the ROM 62. These parameters are transmitted to a target rotation speed generation circuit (not shown) provided in the controller 60, and the target rotation speed generation circuit (not shown) forms a conveyance speed profile based on the parameters. These parameters are recorded in the ROM 62 at the manufacturing stage of the transport apparatus 10.

In the medium transport operation, when the output signal Sen from the rotary encoder 34 is input to the controller 60 as a control unit, the current rotational position P of the transport motor 33 (or the transport roller 31a) is determined based on the output signal Sen. The current rotational speed V is calculated respectively. Then, a deviation ΔP between the target rotational position Pt and the current rotational position P is obtained, and a target rotational speed Vt corresponding to the rotational position deviation ΔP is generated based on the conveyance speed profile shown in FIG.

In the transport speed profile of FIG. 3, the medium is uniformly accelerated during the time Tacc after the start of transport and reaches the transport speed Vcc (acceleration region). After reaching Vcc, the acceleration becomes zero, and the conveyance at a constant speed is performed at the conveyance speed Vcc for a time Tc (constant speed region). Then, after the conveyance is performed at a constant speed, the deceleration is started, the speed is uniformly decelerated during the time Tbcc, the speed becomes zero, and the conveyance is stopped (deceleration region). As a result, time Tt (= Tacc +
During the time Tc + Tbcc), the medium is transported. That is, Tt is the entire transport time.

Note that the sum of the hatched areas represented by the sections of the acceleration region, constant velocity region, and deceleration region in FIG. 3 represents the “conveyance amount” of the medium in a series of conveyance operations.

When speed control is performed based on such a conveyance profile, the acceleration or deceleration increases as the slope becomes steeper in the acceleration region and the deceleration region, and the inertial force acting on the conveyed medium also increases. In particular, it becomes a problem when the deceleration is large during the deceleration operation. For example, even if the speed is zero on the profile after the time Tt has elapsed from the start of conveyance, the medium actually stops at the target stop because the inertial force actually acts and the medium conveyance operation cannot be stopped suddenly. There is a risk of passing the position. In other words, the greater the deceleration, the greater the inertial force, so that the stop accuracy deteriorates and accurate conveyance cannot be performed.

<Comparative example 2>
Then, about the method of suppressing that conveyance accuracy deteriorates like the comparative example 1, the comparative example 2
FIG. 4 described below shows a speed profile of the conveyance speed in Comparative Example 2. In addition,
Also in FIG. 4, as in FIG. 3, the area of the area represented by the hatched portion indicates the transport amount of the medium. In order to make the conveyance amount of the medium the same in Comparative Example 1 and Comparative Example 2, it is assumed that the area of the hatched portion of the speed profile shown in FIGS. 3 and 4 is equal. For reference, the speed profile of Comparative Example 1 is indicated by a broken line.

In the speed profile of Comparative Example 2, the acceleration operation in the acceleration region and the constant speed operation in the constant speed region are the same as in Comparative Example 1, and the manner of deceleration in the deceleration region is different (see the broken line portion). Specifically, the deceleration time Tbcc is made longer than the acceleration time Tacc during the transport time Tt.
In the deceleration range, immediately after the transition from the constant speed operation to the deceleration operation, the deceleration starts with a large deceleration and gradually decreases with the passage of time. Make it smaller. That is, as shown in the deceleration region in FIG. 4, the speed profile is such that the conveyance speed gradually decreases. As a result, the conveyance speed is very small in the area immediately before the medium conveyance is stopped, and the inertial force applied to the medium is also very small.
Therefore, the problem that the conveyed medium passes the target stop position does not occur, and the stop accuracy can be improved as compared with the case of the first comparative example.

On the other hand, in the case of the comparative example 2, since the deceleration time Tbcc becomes longer as shown in FIG. 4, the time Tt (= Tacc + Tc + Tbcc) of the entire transport operation from the start of transport to the end of transport also becomes longer. Accordingly, the transport time Tt required for transporting the same distance is increased, and the throughput of the transport apparatus 10 is reduced.

=== First Embodiment ===
In the first embodiment, the medium is transported using a speed profile that can improve the stop accuracy without reducing the throughput of the transport device 10.
FIG. 5 shows a speed profile of the conveyance speed in the first embodiment. The speed profile of the present embodiment is shown by the solid line in FIG. 5, and for reference, the profile described in FIG. 3 of Comparative Example 1 is shown by a broken line.

In the first embodiment, acceleration is made larger in the acceleration region than in the case of Comparative Examples 1 and 2 described above, and in the deceleration region, the deceleration immediately after the start of deceleration is made larger in the same manner as in Comparative Example 2, so that time is increased. Decrease the deceleration gradually as time passes. In this embodiment, the acceleration operation is directly shifted to the deceleration operation without providing a constant speed region.

In the acceleration range, the conveyance of the medium is started at a predetermined acceleration from the stop state, and the acceleration is performed until the maximum speed Vmax is reached. Here, as shown in FIG. 5, the inclination of the acceleration is larger than the acceleration described in Comparative Example 1 and Comparative Example 2 (the inclination of the broken line), and the acceleration time Tacc until reaching Vmax due to the large acceleration. Is to be as short as possible.

Further, by providing the deceleration region longer than the acceleration region, the deceleration operation is moderated as in the case of Comparative Example 2. That is, the deceleration time Tabb is set longer than the acceleration time Tacc. Immediately after the start of deceleration, deceleration is started with a large deceleration, and the deceleration is reduced with the passage of time. The deceleration operation is performed so that the deceleration is minimized immediately before the stop. As a result, the deceleration gradually decreases with the start of the deceleration operation, and the transport speed gradually decreases, so that the stopping accuracy can be improved.

In this embodiment, after the transport speed reaches Vmax, the deceleration operation is started immediately without performing constant speed transport. That is, the acceleration operation is performed until the deceleration operation is started. As a result, the constant speed region time Tc of the entire transport time Tt (= Tacc + Tc + Tbcc).
Becomes zero and is expressed as Tt = (Tacc + Tbcc). Therefore, the transport time Tt can be made shorter than in the case of the comparative example described above.

The carry amount is represented by the area of the shaded portion in FIG. In order to make it equal to the transport amount in the case of the comparative example described above, the area of the shaded portion in FIG. 5 needs to be made equal to the area of the shaded portion in FIGS. Accordingly, the amount of conveyance of the medium is adjusted by changing the area of the hatched portion by changing the magnitude of the maximum speed Vmax or the shape of the deceleration curve in the deceleration region of FIG.

<Effects of First Embodiment>
In the first embodiment, the deceleration time is made longer than the acceleration time in the deceleration region of the transport operation,
Speed control is performed so that the deceleration gradually decreases. That is, the conveyance speed is gradually decreased. In addition, acceleration is performed with a larger acceleration than in the past in the acceleration region of the transport operation.
Then, after reaching the maximum speed, deceleration is started immediately without shifting to constant speed conveyance. In other words, the acceleration operation is performed until the deceleration operation is started.

As a result, the conveyance speed immediately before the stop can be reduced as much as possible, and the medium can be accurately stopped at the target stop position. That is, the conveyance accuracy of the conveyance device can be improved. If the conveyance accuracy (stopping accuracy) is improved, the desired conveyance accuracy can be ensured even if the resolution of the detection device such as a rotary encoder is reduced, so that the cost of the detection device can be kept low. Space can also be achieved. Further, the entire transport time can be shortened by shortening the acceleration time required to reach the maximum speed and further reducing the time required for performing the constant speed operation.

That is, according to the method of the first embodiment, it is possible to reduce the time required for the entire transport operation from the start of transport to the stop while securing the transport accuracy. Both throughput can be improved.

<Modification of First Embodiment>
In the first embodiment, the speed control is performed based on a speed profile (see FIG. 5) in which the acceleration operation is performed until the deceleration operation is started. That is, the entire conveyance time is shortened by not providing the constant speed region. Moreover, the acceleration time was shortened by making the acceleration in the acceleration region larger than before.

Here, when the acceleration is very large, the acceleration direction suddenly changes in a short time at the timing of switching from the acceleration operation to the deceleration operation, so oscillation occurs in the speed control and accurate conveyance cannot be performed. There is. Further, such a rapid change in speed gives a very large load to the medium transport mechanism 30, which may cause the transport device 10 itself to break down.

Therefore, a case will be described in which a speed profile is used in which the change in speed when shifting from the acceleration operation to the deceleration operation is minimized by changing the deceleration operation stepwise in the deceleration range. FIG. 6 shows a speed profile of the conveyance speed in the modification of the first embodiment.

In FIG. 6, the deceleration region is divided into two regions, a first deceleration region and a second deceleration region.
In the first deceleration area adjacent to the acceleration area, the deceleration is small, and the change in the conveyance speed during medium conveyance is moderate. When shifting from acceleration to deceleration, instead of abruptly changing from a large acceleration to a large deceleration, the first is a gentle change from a large acceleration to a small deceleration. . In other words, the first deceleration region has a role as a buffer region that softens a large speed fluctuation when shifting from the acceleration operation to the deceleration operation, and facilitates control of the speed change. However, if such a gradual speed decrease (first deceleration area) continues for a long time, the entire transport time Tt becomes longer. Therefore, the deceleration is further changed at a predetermined timing (second deceleration area) to reduce the speed. The total time Tbcc (the total time of the first deceleration area and the second deceleration area) is shortened.

In the second deceleration region adjacent to the first deceleration region, the deceleration is initially increased and the deceleration is decreased immediately before stopping. As a result, while making the length (time) of the second deceleration area as short as possible, the conveyance speed is gradually reduced in the same manner as the deceleration area in the first embodiment described above, and the medium is gently stopped at the target stop position. I try to let them.

In the deceleration region of this modification, when shifting from the first deceleration region to the second deceleration region, the deceleration operation continuously changes from a small deceleration to a large deceleration. Therefore, compared with a case where the acceleration operation with a large acceleration is changed to a deceleration operation with a large deceleration, the rate of speed fluctuation is small, and oscillation and the like are less likely to occur.

As described above, when the acceleration is large, when the transition from the acceleration region to the deceleration region is performed, a portion serving as a buffer region is provided in the deceleration region, and a sudden speed fluctuation is suppressed by performing stepwise deceleration. Thereby, the continuous control about the speed change control of the conveying apparatus 10 can be facilitated, and the failure of the device can be suppressed.

In the example of FIG. 6, the two-stage deceleration operation (first and second deceleration areas) is performed in the deceleration region, but the deceleration operation may be divided into three or more steps.

=== Second Embodiment ===
In the second embodiment, among the speed profiles described in the first embodiment, there are a plurality of deceleration profiles that define the deceleration operation. And the conveyance speed is the maximum speed Vmax
The speed control is performed by selecting an optimum deceleration profile from such profiles in accordance with the conditions at the time of reaching.

As described above, the conveyance speed is controlled based on the target rotation speed Vt generated based on the conveyance speed profile. However, in the state where the medium is actually transported,
There may be a problem that the actual conveyance speed is deviated from the target speed, or the acceleration is too large to perform accurate control. In such a case, if an attempt is made to decelerate based on the original conveyance speed profile, there is a possibility that an excessive load is applied to the conveyance mechanism 30 or the conveyance amount becomes inaccurate. Therefore, at the timing of shifting from the acceleration operation to the deceleration operation, a pattern capable of performing the optimum deceleration operation is selected from a plurality of preset deceleration profile patterns, and the deceleration operation is performed.

FIG. 7 shows an example of a deceleration profile pattern set in advance. In the figure, examples of deceleration patterns of three patterns of profiles A to C are shown. Assuming that profile A is a standard profile example, profile B represents an example when the acceleration time becomes long, and profile C represents an example when the acceleration time becomes short. These profiles are
It is set in the manufacturing stage of the transport device 10 and stored in the ROM 62 of the controller 60. Note that the number of speed profiles to be set is arbitrary, and is determined in consideration of the application and operating conditions of the transport apparatus 10.

In the present embodiment, the acceleration time Tacc (arrival time) from the start of conveyance to the start of acceleration until the conveyance speed reaches the maximum speed Vmax is detected, and the deceleration profile is selected based on the detected time. Done. For example, if the detected arrival time is a,
The controller 60 performs the deceleration operation by selecting the deceleration profile A (profile drawn with a solid line) in FIG. As described in the first embodiment, the deceleration profile A suddenly decelerates with a large deceleration at the start of deceleration, and then gradually decreases with time. Then, the conveyance speed is minimized immediately before the conveyance operation is stopped, so that the conveyance time is as short as possible while ensuring the conveyance accuracy.

Further, when the detected arrival time is b (a <b), the controller 60 determines that FIG.
The deceleration profile B (profile drawn with a one-dot chain line) is selected to perform the deceleration operation. Since the time b until reaching the maximum speed is longer than a, the slope in the acceleration region becomes gentler and the acceleration becomes smaller. Therefore, the deceleration at the time of shifting to the deceleration operation is lower than that in the profile A. Can be bigger. Even in such a case, it is difficult for the speed to fluctuate rapidly, so that an excessive load is not applied to the transport mechanism 30. On the other hand, since a longer time is required for the acceleration operation, the entire conveyance time Tt is kept short by shortening the deceleration time accordingly. That is, when shifting from the acceleration operation to the deceleration operation, deceleration is started with a larger deceleration, the acceleration is gradually decreased with the passage of time, and finally the operation is stopped gently. As a result, it is possible to shorten the entire transport time while realizing an accurate transport operation.

In addition, when the detected arrival time is c (c <a), the controller 60 performs FIG.
Deceleration profile C (profile drawn with a two-dot chain line) is selected to perform a deceleration operation. The fact that the time c until reaching the maximum speed is shorter than a means that the slope becomes steeper and the acceleration increases. Therefore, the deceleration at the time of shifting to the deceleration operation is made smaller than that in the profile A. There must be. Otherwise, rapid speed fluctuations occur and an excessive load is applied to the transport mechanism 30. On the other hand, since the time required for the acceleration operation becomes shorter, the deceleration time can be increased accordingly. Therefore, the deceleration operation is a two-stage deceleration as shown in FIG. 6 described above, starting with a small deceleration at first, then decelerating with a large deceleration, and gradually decreasing the deceleration from there. To go. Thereby, since conveyance can be stopped slowly, the whole conveyance time can be shortened, implement | achieving exact conveyance amount.

In the above-described example, in the transport operation, the deceleration profile is selected based on the elapsed time from the start of transport until the transport speed reaches the maximum speed Vmax. However, the deceleration profile is selected based on other parameters. May be selected. For example, the speed profile may be selected in accordance with the amount of medium transport at the time when the transport speed reaches the maximum speed Vmax and the time until the predetermined transport speed is reached.

<Effects of Second Embodiment>
In the second embodiment, a plurality of deceleration profiles are prepared in advance, and the optimum deceleration profile is selected and the deceleration operation is performed according to the actual transport operation conditions when shifting from the acceleration operation to the deceleration operation. Do.
Since the deceleration operation can be appropriately selected based on the actual acceleration operation, it is possible to control the overall conveyance time to be shortened while realizing more accurate medium conveyance.

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

<About media>
In each of the above-described embodiments, the transport medium is described as paper or the like. However, a medium other than “paper” may be used as long as the medium is a sheet that can be transported by the medium transport mechanism. For example,
A film-like member, a resin sheet, an aluminum foil, or the like can be used as a medium.

<About the control unit>
The controller 60 is not limited to that of the above-described embodiment. For example, the controller 60 may be configured to control the PF motor 33 using only the ASIC 65, and a single chip in which various peripheral devices other than these are incorporated. The controller 60 may be configured by combining microcomputers or the like.

10 Conveying device,
30 medium transport mechanism, 31 transport roller pair, 32 gear train,
33 PF motor, 34 rotation detector, 35 discharge roller pair,
60 controller

Claims (6)

(A) a transport mechanism for transporting the medium;
(B) Acceleration operation that is an operation when the transport mechanism starts transporting the medium and accelerates the transport speed of the medium; and the transport mechanism decelerates the transport speed of the medium and transports the medium. About the deceleration operation that is the operation when stopping
A control unit that makes the time required for the deceleration operation longer than the time required for the acceleration operation between the start of conveyance of the medium and the stop of conveyance of the medium;
A conveying device comprising:
The control unit causes the transport mechanism to perform the acceleration operation until the deceleration operation is started.
It is a conveying apparatus of Claim 1, Comprising:
When carrying out the deceleration operation, the deceleration decreases with the passage of time.
It is a conveying apparatus of Claim 1 or 2, Comprising:
The deceleration operation has a first deceleration operation and a second deceleration operation,
In the first deceleration operation, when shifting from the acceleration operation, a deceleration operation is performed at a predetermined deceleration rate.
In the second deceleration operation, the transfer device performs a deceleration operation with a larger deceleration than the predetermined deceleration operation when shifting from the first deceleration operation. It is a conveying apparatus in any one of Claims 1-3,
There are several types of speed profiles that specify the deceleration operation.
The control unit, according to the condition at the time of causing the transport mechanism to perform the acceleration operation,
An optimum speed profile is selected from the plurality of speed profiles,
A transport apparatus that causes the transport mechanism to perform the deceleration operation based on the selected speed profile. It is a conveyance apparatus of Claim 4, Comprising:
The control unit, according to the time from the start of transport when the transport mechanism performs the acceleration operation until the predetermined transport speed is reached,
An optimum speed profile is selected from the plurality of speed profiles,
A transport apparatus that causes the transport mechanism to perform the deceleration operation based on the selected speed profile. (A) transporting the medium by a transport mechanism;
(B) Acceleration operation that is an operation when the transport mechanism starts transporting the medium and accelerates the transport speed of the medium; and the transport mechanism decelerates the transport speed of the medium and transports the medium. About the deceleration operation that is the operation when stopping
Between the start of transport of the medium and the stop of transport of the medium, the time required for the deceleration operation is made longer than the time required for the acceleration operation.
By controller
A transport method comprising causing the transport mechanism to perform the acceleration operation until the deceleration operation is started.

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