JP5814648B2 - Medium transport device - Google Patents

Description

  The present invention relates to a medium conveying apparatus that detects a feed amount of an endless belt by an encoder and corrects a designated feed amount.

  In belt conveyance adopted as a conveyance mechanism of an ink jet printer, a flexible endless belt that conveys media such as cloth and paper is wound around a pair of rollers, and the rollers are rotated by a drive motor. The belt is moved. The actual feed amount of the belt varies with respect to the specified feed amount due to the eccentricity of the roller and the uneven thickness of the belt. Therefore, the actual amount of movement is detected by the rotary encoder provided on the belt. The motor drive signal is corrected by the signal.

  A belt device disclosed in Patent Document 1 is known as a technique for correcting such roller eccentricity fluctuation and belt thickness fluctuation. The belt device includes a first roller that is a driving roller, a second roller that is a driven roller, an endless belt that is wound between the first roller and the second roller, And a counter roller provided to be opposed to the one roller via the belt. Each of the first roller and the opposing roller is provided with a rotary encoder.

The belt device stores fluctuations in the thickness of the belt detected by rotary encoders provided on the first roller and the counter roller, and eccentric fluctuations of the first roller and the counter roller, respectively. Based on the above, the drive signal of the drive motor is corrected, and the first roller is rotated so that the movement speed fluctuation or movement speed distance fluctuation of the belt is reduced.

  The endless belt is processed into a finger shape at both ends of a strip-shaped belt, and the both ends are joined together by laminating an adhesive sheet from above the abutting portion to form an annular shape as a whole. Structure. For this reason, such a joint exists in the endless belt, and the belt thickness variation at the joint is larger than the thickness variation of other portions. For this reason, there is a problem that it is difficult to obtain an accurate feed amount in the correction method in the conventional belt device that corrects a relatively small variation in thickness in the entire circumference of the belt.

  Further, an ink jet plotter described in Patent Document 2 is known as a technique for eliminating a detection error at a joint portion. This inkjet plotter is a technique for detecting the position of a slider that holds an inkjet head. The slider is provided with a first linear encoder sensor and a second linear encoder sensor. The linear encoder scale has a structure in which a first linear encoder scale and a second linear encoder scale are joined by a joint portion. The scale of the first linear encoder scale is read by the first linear encoder sensor, and the scale of the second linear encoder scale is read by the second linear encoder sensor.

When the detection means detects that the first linear encoder sensor has approached the joint, the traveling position detection means switches so that the scale of the second linear encoder scale is read by the second linear encoder sensor. In this way, even if the linear encoder scale has a joint, the scale of the linear encoder scale can be read continuously.

  However, if a linear encoder scale as in Patent Document 2 is provided on a flexible belt as in Patent Document 1, the distance from the linear encoder scale to the linear encoder sensor becomes unstable due to vibration of the belt, and an accurate feed is made. There was a problem that the amount could not be detected.

JP 2009-86653 A JP 2001-341372 A

Accordingly, an object of the present invention is to enable accurate detection of the feed amount of a flexible belt having a joint.

According to a first aspect of the present invention, there is provided a medium conveying device according to a first aspect of the present invention, wherein a flexible belt having a joint at a joined portion and a feed amount of the belt in a state where the belt is always held by a holding means. A detection unit; a second detection unit that is provided with a gap larger than a width of the joint from the first detection unit; and that detects a feed amount of the belt in a state where the belt is always held; and a belt by the first detection unit In this case, the detection means for detecting the feed amount of the belt is changed from the first detection means to the second detection means before the first detection means is positioned on the joint. possess a switching means for switching to said first detection means or second detection means comprises a non-contact sensor that detects the detected portion which is formed at a portion which is driven in the belt or belt in a non-contact, said Be A mark is provided to avoid the seam, and is provided corresponding to the first detection means, provided with first mark detection means for detecting the mark on the belt, provided corresponding to the second detection means, Second mark detection means for detecting a mark on the belt is provided, and the switching means includes first detection means for detecting a feed amount of the belt when the mark on the belt is detected by the first mark detection means. In the case where the detection means is switched to the second detection means and the belt feed amount is detected by the second detection means, and the mark on the belt is detected by the second mark detection means, the belt feed is detected. The detection means for detecting the amount is switched from the second detection means to the first detection means .

That is, in the present invention, the feed amount of the belt is detected in a state where the flexible belt is always held by the holding means, so that, for example, when a belt is provided with a linear scale, even if vibration occurs in the belt. The distance from the linear scale to the sensor becomes stable, and as a result, the feed amount of the belt can be accurately detected. Even when the first detecting means is configured by combining a nipping means comprising a roller and a rotary encoder that detects the feed amount from the rotation of the roller, the feed amount of the belt can be accurately determined even if belt vibration occurs. Can be detected. Further, the interval between the first detection means and the second detection means is made larger than the joint of the belt, and then the first detection means is positioned before the first detection means is positioned on the joint. Since the belt feed amount is detected by the second detection means by switching from the means to the second detection means, it is not necessary to detect the belt feed amount at the belt joint. The feed amount can be accurately detected.
Even if the belt is vibrated or stretched by detecting the detected portion on the belt held by the holding means with a non-contact sensor, the feed amount of the belt can be accurately detected. The non-contact sensor is, for example, an optical sensor, and the detected part is a linear scale or a rotary slit.
That is, in the present invention, the first mark detection means detects a mark provided avoiding the belt joint, and the second detection means is switched from the first detection means to the second detection means based on the detection of the mark. To detect the feed amount of the belt. Since the second detection means is provided with an interval larger than the width of the joint from the first detection means, when the first detection means is located on the joint, the second detection means is on the joint. Will not be located. Therefore, since it is not necessary to detect the belt at the joint portion of the belt, the feed amount of the belt can be accurately detected.
That is, according to the present invention, the first mark detection means and the second mark detection means are provided in association with both the first detection means and the second detection means, and the belt formed by the first mark detection means or the second mark detection means. The detection means is switched based on the detection of the upper mark. As a specific example, in the case where the belt feed amount is detected by the second detection means, the detection means for detecting the belt feed amount when the mark on the belt is detected by the second mark detection means, When the belt is switched from the second detection means to the first detection means and the feed amount of the belt is detected by the first detection means, when the mark on the belt is detected by the first mark detection means, The detection means for detecting the feed amount is switched from the first detection means to the second detection means. Even in this case, it is not necessary to detect the feed amount of the belt at the joint portion of the belt, so that the feed amount can be accurately detected.

According to a second aspect of the present invention, there is provided the medium conveying apparatus according to the first aspect , wherein an interval between the first detection unit and the second detection unit is half of the belt circumferential length.

  In this way, after the detection unit is switched by detecting the joint, the next switching is not performed unless the belt makes a half turn, so that the number of switching of the detection unit can be reduced. For this reason, processing time is shortened.

  According to the present invention, detection is performed by the detection means in a state where the flexible belt causing vibration or expansion / contraction is held by the holding means, and at that time, the joint of the belt is not detected by the detection means. Therefore, the feed amount of the belt can be accurately detected.

It is explanatory drawing which shows the belt-type conveying apparatus which concerns on Embodiment 1 of this invention, (a) is a top view (b) is a side view. FIG. 2 is a partial perspective view of the belt type conveyance device shown in FIG. 1. It is a block diagram which shows the belt-type conveying apparatus shown in FIG. It is explanatory drawing which shows operation | movement of the belt type conveying apparatus of this invention. It is explanatory drawing which shows operation | movement of the belt-type conveying apparatus which concerns on Embodiment 2 of this invention. It is a side view which shows the belt-type conveying apparatus which concerns on Embodiment 3 of this invention. It is a schematic diagram which shows the correlation between each encoder and the joint of a belt. It is explanatory drawing which shows operation | movement of the belt-type conveying apparatus which concerns on Embodiment 4 of this invention. It is explanatory drawing which shows operation | movement of the belt-type conveying apparatus which concerns on Embodiment 5 of this invention. It is explanatory drawing which shows operation | movement of the belt-type conveying apparatus which concerns on Embodiment 6 of this invention. It is a partial perspective view which shows the belt-type conveying apparatus which concerns on Embodiment 7 of this invention. It is a side view which shows the belt-type conveying apparatus shown in FIG. It is a partial perspective view which shows the belt-type conveying apparatus which concerns on the modification of Embodiment 7 of this invention.

(Embodiment 1)
FIG. 1 is an explanatory view showing a belt type conveying apparatus according to Embodiment 1 of the present invention, in which (a) is a plan view (b) is a side view. FIG. 2 is a partial perspective view of the belt-type transport device shown in FIG. FIG. 3 is a configuration diagram illustrating the belt-type conveyance device illustrated in FIG. 1. This belt type conveyance device 100 is a medium conveyance device used for conveyance of a medium such as a cutting plotter or an ink jet printer, and a flexible and endless belt 53 is provided between a first roller 51 and a second roller 52. It is a hung structure.

A first rotary encoder 1 and a second rotary encoder 2 are provided on one side edge of the belt 53 at regular intervals. This constant interval is at least larger than the width of the joint 54. For this reason, when the 1st rotary encoder 1 which is a 1st detection means is located on the joint 54, the 2nd rotary encoder 2 which is a 2nd detection means will not be located on the joint 54. FIG.

In the first rotary encoder 1 and the second rotary encoder 2, a casing in which a slit plate and an optical sensor that rotate in conjunction with the belt 53 are installed is fixed to a fixing bracket, and the belt 53 is attached to a rotating shaft. Are provided with detection rollers 11 and 21 that contact with each other at a predetermined pressure. Surfaces for obtaining a predetermined frictional force are applied to the contact surfaces of the detection rollers 11 and 21 with the belt 53. Auxiliary rollers 12 and 22 are provided opposite to the detection rollers 11 and 21 via a belt 53. The detection rollers 11 and 21 are driven by the auxiliary rollers 12 and 22 without being caused to slip by sandwiching the belt 53 with a predetermined pressure. Even if the flexible belt 53 vibrates or stretches, the slit plate that is driven by the roller is provided by always holding the belt 53 by the detection roller and the auxiliary roller that are the holding means. It can be detected stably by an optical sensor.

  Further, an optical sensor 13 as a first mark detection means is provided in the vicinity of the first rotary encoder 1 and on the side where the second rotary encoder 2 is provided. The optical sensor 13 includes a light source 14 such as a light emitting diode and a light receiving element 15 such as a photodiode. The light source 14 is disposed on the front side of the belt 53, and the light receiving element 15 is disposed on the back side of the belt 53.

  A drive motor 61 is provided on the rotation shaft of the first roller 51. The drive motor 61 is driven by the driver unit 62. The driver unit 62 is connected to the controller 63. The controller 63 is connected to the first rotary encoder 1, the second rotary encoder 2, and the optical sensor 13. The controller 63 includes a switching unit 64 that switches a detection signal used for correction among detection signals of the first rotary encoder 1 and the second rotary encoder 2, and a correction unit 65 that corrects the feed amount.

  The belt 53 has a belt-like joint 54 having a certain width in a direction orthogonal to the transport direction. The joint 54 has a structure in which both ends of a long strip-shaped belt 53 are processed into a finger shape, the both ends are butted and an adhesive sheet is laminated thereon, and the thickness of the joint 54 is other than that. It is thicker than the part. In the vicinity of the front side of the belt 53 in the feed direction, a hole as a mark 55 indicating the presence of the joint 54 is provided. In other words, the mark 55 is provided on the belt 53 so as to avoid the joint 54. This hole can be detected by the optical sensor 13.

  FIG. 4 is an explanatory view showing the operation of the belt type conveying apparatus of the present invention. In the figure, it is assumed that the belt 53 moves in the conveyance direction indicated by the arrow A. As described above, one optical sensor 13 is provided in the vicinity of the second rotary encoder side (or back feed side) of the first rotary encoder 1, and one mark 55 is provided in the vicinity of the feed side of the joint 54 of the belt 53. One shall be provided. Further, in the drawing, “effective” is written for the rotary encoder that actually detects the feed amount of the belt 53.

In the state shown in FIG. 4A, the first rotary encoder 1 is selected by the switching unit 64 as an encoder that actually detects the feed amount of the belt 53. The correction unit 65 corrects the designated feed amount based on the detection signal from the first rotary encoder 1. The driver unit 62 drives the drive motor 61 with the corrected drive signal. In the state of FIG. 4A, the joint 54 on the belt 53 does not reach the second rotary encoder 2.

When the conveyance of the belt 53 proceeds, the joint 54 passes through the second rotary encoder 2 as shown in FIG. 4B, but the detection signal of the second rotary encoder 2 at this time is not used, so correction is performed. There is no influence on the feed amount correction accuracy by the unit 65.

  When the belt 53 further moves and the mark 55 enters the detection position of the optical sensor 13 as shown in FIG. 4C, the light from the light source 14 of the optical sensor 13 passes through the hole (55) and is received. When the element 15 receives light, the optical sensor 13 detects the mark 55. The controller 63 controls the drive motor 61 based on the detection signal of the mark 55 to stop the belt 53. The switching unit 64 switches the “effective” rotary encoder from the first rotary encoder 1 to the second rotary encoder 2 based on the detection signal of the mark 55.

  Since the first rotary encoder 1 and the second rotary encoder 2 are arranged at a constant interval, errors due to eccentricity of the rollers and thickness variation of the belt 53 occur. That is, the belt 53 between the first rotary encoder 1 and the second rotary encoder 2 slightly expands and contracts due to the eccentricity of the rollers. Further, the thickness of the belt 53 at the positions of the first rotary encoder 1 and the second rotary encoder 2 is slightly different. For this reason, when switching from the first rotary encoder 1 to the second rotary encoder 2, the actual distance between the first rotary encoder 1 and the second rotary encoder 2 (encoder installation distance) and the first on the belt 53. There is an error between the distance between the rotary encoder 1 and the second rotary encoder 2 (distance obtained from the detection signal of the encoder). In addition, since the detection signals obtained by the individual differences of the encoders are different, it is necessary to consider errors caused by the individual differences. In the storage unit 66 shown in FIG. 3, individual errors caused by the eccentricity of these rollers, belt thickness fluctuations, and individual differences of encoders are acquired and stored in advance. Then, the correction unit 65 reads out the individual error stored in the storage unit 66 when the encoder is switched, and performs correction to fill it.

  Returning to FIG. 4C, the first rotary encoder 1 is switched to the second rotary encoder 2, and the correction unit 65 corrects an error necessary for the encoder switching, and then the drive motor 61 is driven again to drive the belt. 53 is moved. The correcting unit 65 corrects the designated feed amount based on the detection signal from the second rotary encoder 2. The detection signal from the first rotary encoder 1 is not used.

  Subsequently, as shown in FIG. 4D, after the joint 54 passes through the first rotary encoder 1 and the optical sensor 13 detects the mark 55 (after switching to the second rotary encoder 2), a predetermined value is obtained. When the belt 53 moves by the feed amount (switching feed amount x1), the switching unit 64 switches the rotary encoder used for the first rotary encoder 1 from the second rotary encoder 2. The feed amount is detected based on a detection signal from the second rotary encoder 2. The switching feed amount x1 needs to be larger than the distance x2 from the mark 55 to the end of the joint 54 opposite to the mark 55 side. This is because the feed amount is not detected at the joint 54 by the first rotary encoder 1.

Further, when switching from the second rotary encoder 2 to the first rotary encoder 1, as described above, the movement of the belt 53 is stopped and correction for filling the individual error is performed. After correction, the drive motor 61 is driven again to move the belt 53. The correction unit 65 corrects the designated feed amount based on the detection signal from the first rotary encoder 1 after switching the rotary encoder.

  As described above, the mark 55 provided in the vicinity of the joint 54 is detected by the optical sensor 13, and the encoder 53 is switched to another encoder based on the detection signal, and the feed amount of the belt 53 is detected by the encoder. Therefore, the encoder that performs the detection does not detect the feed amount of the belt 53 at the joint 54 of the belt 53. For this reason, since it is not necessary to consider the large fluctuation of the belt thickness due to the joint 54, the feed amount of the flexible belt 53 can be accurately detected.

(Embodiment 2)
FIG. 5 is an explanatory view showing the operation of the belt type conveying apparatus according to the second embodiment of the present invention. The belt-type transport device 200 has substantially the same configuration as the belt-type transport device 100 according to the first embodiment, but is in the vicinity of the second rotary encoder 2 and the side on which the first rotary encoder 1 is provided. Is different in that an optical sensor 23 as second mark detection means is provided on the opposite side. The optical sensors 13 and 23 are the same as those in the first embodiment.

In the figure, it is assumed that the belt 53 moves in the conveyance direction indicated by the arrow A. One optical sensor 13, 23 is provided near the back feed side of the first rotary encoder 1 and the second rotary encoder 2, and one mark 55 is provided near the feed side of the joint 54 of the belt 53. It shall be. Further, in the drawing, “effective” is written for the rotary encoder that actually detects the feed amount of the belt 53.

In the state shown in FIG. 5A, the second rotary encoder 2 is selected by the switching unit 64 as an encoder that actually detects the feed amount of the belt 53. The correction unit 65 corrects the designated feed amount based on the detection signal from the second rotary encoder 2. The driver unit 62 drives the drive motor 61 with the corrected drive signal. In the state of FIG. 5A, the joint 54 on the belt 53 does not reach the second rotary encoder 2.

  When the conveyance of the belt 53 advances and the mark 55 provided in the vicinity of the joint 54 enters the detection position of the optical sensor of the second rotary encoder 2 as shown in FIG. When the light passes through the hole and the light receiving element receives the light, the optical sensor 23 detects the mark 55. The controller 63 controls the drive motor 61 based on the detection signal of the mark 55 to stop the belt 53. Then, the switching unit 64 switches the “valid” encoder from the second rotary encoder 2 to the first rotary encoder 1 based on the detection signal of the mark 55. When the encoder is switched, the correction unit 65 reads the individual error stored in the storage unit 66 shown in FIG. 3 and corrects the error.

Returning to FIG. 5B, the second rotary encoder 2 is switched to the first rotary encoder 1, and the correction unit 65 corrects an error required when switching the encoder, and then the drive motor 61 is driven again to drive the belt. 53 is moved. The correction unit 65 corrects the designated feed amount based on the detection signal from the first rotary encoder 1.

  As shown in FIG. 5C, the joint 54 of the belt 53 passes through the second rotary encoder 2, but the detection signal of the second rotary encoder 2 at this time is not used. There is no effect on the correction accuracy of the quantity.

  Next, as shown in FIG. 5D, when the mark 55 provided in the vicinity of the joint 54 with the movement of the belt 53 enters the detection position of the optical sensor 13 of the first rotary encoder 1, the optical sensor 13. Detects the mark 55. The controller 63 controls the drive motor 61 based on the detection signal of the mark 55 to stop the belt 53. Then, the switching unit 64 switches the “valid” encoder from the first rotary encoder 1 to the second rotary encoder 2 based on the detection signal of the mark 55. When the encoder is switched, the correction unit 65 reads the individual error stored in the storage unit 66 and performs correction to fill it.

After switching from the first rotary encoder 1 to the second rotary encoder 2 and correcting the error required when the encoder is switched by the correction unit 65, the controller 63 drives the drive motor 61 again to move the belt 53. . The correcting unit 65 corrects the designated feed amount based on the detection signal from the second rotary encoder 2.

As shown in FIG. 5E, the joint 54 of the belt 53 passes through the first rotary encoder 1, but the detection signal from the first rotary encoder 1 is not used. There is no effect on the correction accuracy.

  The joint 54 makes one round between the first roller 51 and the second roller 52 wound by the movement of the belt 53 and reaches the second rotary encoder 2 again as shown in FIG. Thereafter, the same steps as shown in FIGS. 5B to 5E are repeated.

  As described above, the same effects as those of the belt-type conveyance device 100 of the first embodiment can be obtained, and the optical sensors 13 and 23 are provided in the first rotary encoder 1 and the second rotary encoder 2, respectively. The mark 55 is detected before the joint 54 of the belt 53 passes through each encoder, and it is possible to prevent the encoder from detecting the feed amount at the joint 54. For this reason, the belt 53 can be accurately fed.

(Embodiment 3)
FIG. 6 is a side view showing a belt type conveying apparatus according to Embodiment 3 of the present invention. FIG. 7 is a schematic diagram showing a correlation between each encoder and a belt joint. The belt-type conveyance device 300 according to the third embodiment has substantially the same configuration as the belt-type conveyance device 100 according to the first embodiment, but the second rotary encoder 2 is provided on the opposite side of the loop of the belt 53. There is a feature in that. Preferably, the interval x between the first rotary encoder 1 and the second rotary encoder 2 is half the circumferential length of the belt 53. Thereby, it is possible to prevent frequent switching of the encoder.

  In particular, widening the interval x between the first rotary encoder 1 and the second rotary encoder 2 is effective when the belt 53 is back-fed. In the example shown in FIG. 4, when the joint 54 reaches the first rotary encoder 1 and the first rotary encoder 1 is switched to the second rotary encoder 2, the belt 53 is fed back. Since the joint 54 reaches the second rotary encoder 2 again, the feed of the belt 53 must be stopped again and switched from the second rotary encoder 2 to the first rotary encoder 1. In this case, when the media is installed in the vicinity of the joint 54 of the belt 53, the number of times of switching of the encoder increases, so that processing takes time.

Therefore, as in the third embodiment, the distance x between the first rotary encoder 1 and the second rotary encoder 2 is set to the maximum so that the distance x is half of the belt circumferential length. Even when installed in the vicinity of 53 joints 54, the number of encoder switching operations can be prevented from increasing. The configuration according to the third embodiment can also be applied to the following fourth to sixth embodiments.

(Embodiment 4)
FIG. 8 is an explanatory view showing the operation of the belt type conveying apparatus according to the fourth embodiment of the present invention. The belt-type transport device 400 has substantially the same configuration as the belt-type transport device 100 according to the first embodiment, but the first rotary encoder is used to enable the encoder to be switched when the belt 53 is back-fed. 1 is different from the first rotary encoder 2 in that optical sensors 13 and 16 as first mark detection means and optical sensors 23 and 26 as second mark detection means are provided. The optical sensors 13, 16, 23, and 26 are the same as those in the first embodiment. Another difference is that marks 55 and 56 are provided in the vicinity of both sides of the joint 54 (position avoiding the joint 54).

In the figure, it is assumed that the belt 53 moves in the conveyance direction indicated by the arrow A. The optical sensors 13, 16, 23, and 26 are provided near both sides of the first rotary encoder 1 and the second rotary encoder 2, and marks 55 and 56 are provided near both sides of the joint 54 of the belt 53. Shall. For explanation, the optical sensors on the feed side of the belt 53 of the first rotary encoder 1 and the second rotary encoder 2 are referred to as left optical sensors 16 and 26, and the optical sensors on the back feed side are referred to as right optical sensors 13 and 23. Further, the feed side mark of the joint 54 is referred to as a left mark 55, and the back feed side mark is referred to as a right mark 56. Further, in the drawing, “effective” is written for the rotary encoder that actually detects the feed amount of the belt 53.

In the state shown in FIG. 8A, the second rotary encoder 2 is selected by the switching unit 64 as a rotary encoder that actually detects the feed amount of the belt 53. The correction unit 65 corrects the designated feed amount based on the detection signal from the second rotary encoder 2. The driver unit 62 drives the drive motor 61 with the corrected drive signal. In the state of FIG. 8A, the joint 54 on the belt 53 does not reach the second rotary encoder 2.

  When the conveyance of the belt 53 proceeds and the left mark 55 of the joint 54 enters the detection position of the right optical sensor 23 of the second rotary encoder 2 as shown in FIG. 8B, the right optical sensor 23 is moved to the left mark. 55 is detected. The controller 63 stops the belt 53 by controlling the driving motor 61 based on the detection signal of the left mark 55. Then, the switching unit 64 switches the “valid” encoder from the second rotary encoder 2 to the first rotary encoder 1 based on the detection signal of the left mark 55. When the encoder is switched, the correction unit 65 reads the individual error stored in the storage unit 66 shown in FIG. 3 and corrects the error.

Then, after switching from the second rotary encoder 2 to the first rotary encoder 1 and correcting the error required when the encoder is switched by the correction unit 65, the drive motor 61 is driven again to move the belt 53. The correction unit 65 corrects the designated feed amount based on the detection signal from the first rotary encoder 1.

  As shown in FIG. 8C, the joint 54 of the belt 53 passes through the second rotary encoder 2, but since the detection signal from the second rotary encoder 2 is not used, the feed amount by the correction unit 65 There is no effect on the correction accuracy. 8B to 8C, a signal for detecting the mark 55 is generated four times in total, twice from the right optical sensor 23 of the second rotary encoder 2 and twice from the left optical sensor 26. The switching from the second rotary encoder 2 to the first rotary encoder 1 is performed at the timing of the detection signal generated in step S2.

  Next, as shown in FIG. 8D, when the left mark 55 of the joint 54 enters the detection position of the right optical sensor 13 of the first rotary encoder 1 as the belt 53 moves, the right optical sensor is moved to the left. The mark 55 is detected. The controller 63 stops the belt 53 by controlling the driving motor 61 based on the detection signal of the left mark 55. Then, the switching unit 64 switches the “valid” encoder from the first rotary encoder 1 to the second rotary encoder 2 based on the detection signal of the left mark 55. When the encoder is switched, the correction unit 65 reads the individual error stored in the storage unit 66 and performs correction to fill it.

After the first rotary encoder 1 is switched to the second rotary encoder 2 and the correction unit 65 corrects an error required when the encoder is switched, the drive motor 61 is driven again to move the belt 53. The correcting unit 65 corrects the designated feed amount based on the detection signal from the second rotary encoder 2.

As shown in FIG. 8E, the joint 54 of the belt 53 passes through the first rotary encoder 1, but the detection signal from the first rotary encoder 1 is not used. There is no effect on the correction accuracy. In addition, a signal for detecting the mark 55 is generated twice in total from the right optical sensor 13 of the first rotary encoder 1 and twice from the left optical sensor 16 in FIGS. Switching from the first rotary encoder 1 to the second rotary encoder 2 is performed at the timing of the detection signal generated in step S2.

  When the belt 53 moves only in the feed direction, the joint 54 makes one round between the first roller 51 and the second roller 52 wound by the movement of the belt 53, and as shown in FIG. The second rotary encoder 2 is reached again. After that, the same steps shown in FIGS. 8B to 8E are repeated.

  On the other hand, when the belt 53 back-feeds from the state of FIG. 8C, in the state shown in FIG. 8F, the second rotary encoder 2 is selected as the “effective” encoder. When the right mark 56 of the joint 54 enters the detection position of the left optical sensor 26 of the second rotary encoder 2, the left optical sensor 26 detects the right mark 56. The controller 63 stops the belt 53 by controlling the drive motor 61 based on the detection signal of the right mark 56. Then, the switching unit 64 switches the “valid” encoder from the second rotary encoder 2 to the first rotary encoder 1 based on the detection signal of the right mark 56. When the encoder is switched, the correction unit 65 reads the individual error stored in the storage unit 66 shown in FIG. 3 and corrects the error.

Then, after switching from the second rotary encoder 2 to the first rotary encoder 1 and correcting the error required when the encoder is switched by the correction unit 65, the drive motor 61 is driven again to move the belt 53. The correction unit 65 corrects the designated feed amount based on the detection signal from the first rotary encoder 1.

  Even if the joint 54 passes through the second rotary encoder 2 as it is, since the detection signal from the second rotary encoder 2 is not used, the correction accuracy of the feed amount by the correction unit 65 is not affected at all. Also in this case, four detection signals are generated from the optical sensors 23 and 26 of the second rotary encoder 2, but the encoder is switched at the timing of the first detection signal generated in the same manner as described above.

If the belt 53 is fed back as it is, and the joint 54 makes one turn between the first roller 51 and the second roller 52, the right mark 56 of the joint 54 becomes the first rotary as shown in FIG. The detection position of the left optical sensor 16 of the encoder 1 is entered, and the left optical sensor 16 detects the right mark 56. Based on this detection signal, the switching unit 64 switches from the first rotary encoder 1 to the second rotary encoder 2. After that, the same steps shown in FIGS. 8F to 8H are repeated.

  As described above, the same effect as that of the belt-type conveyance device 100 according to the first embodiment can be obtained, and the mark 55 can be placed before the joint 54 of the belt 53 passes through each encoder even when back feeding is performed. Thus, it is possible to prevent the encoder from detecting the feed amount at the joint 54. For this reason, the belt 53 can be accurately fed.

(Embodiment 5)
FIG. 9 is an explanatory view showing the operation of the belt type conveying apparatus according to the fifth embodiment of the present invention. The belt-type transport device 500 has substantially the same configuration as the belt-type transport device 400 according to the fourth embodiment, but one each for the feed side of the first rotary encoder 1 and the back-feed side of the second rotary encoder 2. The difference is that an optical sensor 16 as a first mark detection means and an optical sensor 23 as a second mark detection means are provided. The optical sensors 16 and 23 are the same as those in the first embodiment. Another difference is that the marks 55 and 56 are provided on both sides of the joint 54 with a predetermined distance.

In the figure, it is assumed that the belt 53 moves in the conveyance direction indicated by the arrow A. For the sake of explanation, the mark 55 on the feed side of the joint 54 is referred to as a left mark 55 and the mark 55 on the back feed side is referred to as a right mark 56. Further, in the drawing, “effective” is written for the rotary encoder that actually detects the feed amount of the belt 53.

In the state shown in FIG. 9A, the second rotary encoder 2 is selected by the switching unit 64 as a rotary encoder that actually detects the feed amount of the belt 53. The correction unit 65 corrects the designated feed amount based on the detection signal from the second rotary encoder 2. The driver unit 62 drives the drive motor 61 with the corrected drive signal. In the state of FIG. 9A, the joint 54 on the belt 53 does not reach the second rotary encoder 2.

  When the conveyance of the belt 53 proceeds and the left mark 55 provided in the vicinity of the joint 54 enters the detection position of the optical sensor 23 of the second rotary encoder 2, as shown in FIG. The left mark 55 is detected. The controller 63 stops the belt 53 by controlling the driving motor 61 based on the detection signal of the left mark 55. Then, the switching unit 64 switches the “valid” encoder from the second rotary encoder 2 to the first rotary encoder 1 based on the detection signal of the left mark 55. When the encoder is switched, the correction unit 65 reads the individual error stored in the storage unit 66 shown in FIG. 3 and corrects the error.

Then, after switching from the second rotary encoder 2 to the first rotary encoder 1 and correcting the error required when the encoder is switched by the correction unit 65, the drive motor 61 is driven again to move the belt 53. The correction unit 65 corrects the designated feed amount based on the detection signal from the first rotary encoder 1.

  As shown in FIG. 9C, the joint 54 of the belt 53 passes through the second rotary encoder 2, but the detection signal from the second rotary encoder 2 is not used. There is no effect on the correction accuracy. 9B to 9C, a signal for detecting the marks 55 and 56 twice is generated from the optical sensor 23 of the second rotary encoder 2, and the second rotary encoder is detected at the timing of the detection signal generated first. Switching from the encoder 2 to the first rotary encoder 1 is performed.

  Next, as shown in FIG. 9D, when the left mark 55 provided in the vicinity of the joint 54 enters the detection position of the optical sensor 16 of the first rotary encoder 1 as the belt 53 moves, the optical sensor 16 detects the left mark 55. Here, the distance x1 from the feed-side end of the joint 54 to the left mark 55 is larger than the distance x2 between the first rotary encoder 1 (the central axis of the detection roller 11) and the optical sensor 16. Thereby, the optical sensor 16 can detect the left mark 55 before the joint 54 enters the first rotary encoder 1.

When the left mark 55 is detected, the controller 63 controls the drive motor 61 to stop the belt 53. Then, the switching unit 64 switches the “valid” encoder from the first rotary encoder 1 to the second rotary encoder 2 based on the detection signal of the left mark 55. When the encoder is switched, the correction unit 65 reads the individual error stored in the storage unit 66 and performs correction to fill it.

After the first rotary encoder 1 is switched to the second rotary encoder 2 and the correction unit 65 corrects an error required when the encoder is switched, the drive motor 61 is driven again to move the belt 53. The correcting unit 65 corrects the designated feed amount based on the detection signal from the second rotary encoder 2.

The joint 54 of the belt 53 passes through the first rotary encoder 1 as shown in FIG. 9E, but the detection signal from the first rotary encoder 1 is not used. There is no effect on the correction accuracy. 9D to 9E, the optical sensor 16 of the first rotary encoder 1 generates a signal for detecting the marks 55 and 56 twice. The first rotary signal is generated at the timing of the first detection signal. Switching from the encoder 1 to the second rotary encoder 2 is performed.

  When the belt 53 moves only in the feed direction, the joint 54 makes one turn between the first roller 51 and the second roller 52 wound by the movement of the belt 53, and as shown in FIG. The second rotary encoder 2 is reached again. Thereafter, the steps shown in FIGS. 9B to 9E are repeated.

  On the other hand, when the belt 53 back-feeds from the state of FIG. 9C, the second rotary encoder 2 is selected as the “effective” encoder in the state shown in FIG. 9F. When the right mark 56 of the joint 54 enters the detection position of the optical sensor 23 of the second rotary encoder 2, the optical sensor 23 detects the right mark 56. The controller 63 stops the belt 53 by controlling the drive motor 61 based on the detection signal of the right mark 56. Then, the switching unit 64 switches the “valid” encoder from the second rotary encoder 2 to the first rotary encoder 1 based on the detection signal of the right mark 56. When the encoder is switched, the correction unit 65 reads the individual error stored in the storage unit 66 shown in FIG. 3 and corrects the error.

  Here, the distance x3 from the end on the back feed side of the joint 54 to the right mark 56 is larger than the distance x4 between the second rotary encoder 2 (the central axis of the detection roller 21) and the optical sensor 23. Thereby, the optical sensor 23 can detect the right mark 56 before the joint 54 enters the second rotary encoder 2.

Then, after switching from the second rotary encoder 2 to the first rotary encoder 1 and correcting the error required when the encoder is switched by the correction unit 65, the drive motor 61 is driven again to move the belt 53. The correction unit 65 corrects the designated feed amount based on the detection signal from the first rotary encoder 1.

  Even if the joint 54 passes through the second rotary encoder 2 as it is, since the detection signal from the second rotary encoder 2 is not used, the correction accuracy of the feed amount by the correction unit 65 is not affected at all. In this case as well, the detection signal is generated twice from the optical sensor 23 of the second rotary encoder 2, but the encoder is switched at the timing of the detection signal generated first.

If the belt 53 is fed back in this state and the joint 54 makes one turn between the first roller 51 and the second roller 52, the right mark 56 of the joint 54 is the first rotary as shown in FIG. 9 (h). The detection position of the optical sensor 16 of the encoder 1 is entered, and the optical sensor 16 detects the right mark 56. Based on this detection signal, the switching unit 64 switches from the first rotary encoder 1 to the second rotary encoder 2. After that, the same steps shown in FIGS. 8F to 8H are repeated.

  With the above configuration, the same effect as that of the belt-type conveyance device 400 according to the fourth embodiment can be obtained, and one optical sensor can be provided for each of the first rotary encoder 1 and the second rotary encoder 2. Go down. The cost is the same even if the distance between the joint 54 and the mark 55 is made larger than that in the fourth embodiment.

  When the mark 55 is provided in the feed direction (back feed direction) of the joint 54 of the belt 53 and the optical sensor is provided in the encoder feed direction (back feed direction), the encoder detection rollers 11 and 21 are provided. The distance between the rotation axis and the optical sensor must be smaller than the distance from the end of the joint 54 in the feed direction (back feed direction) to the mark 55. If this condition is satisfied, the optical sensor may be provided on any side of the first rotary encoder 1, or the optical sensor may be provided on any side of the second rotary encoder 2.

(Embodiment 6)
FIG. 10 is an explanatory view showing the operation of the belt type conveying apparatus according to the sixth embodiment of the present invention. The belt-type transport device 100 has substantially the same configuration as the belt-type transport device 100 according to the fourth embodiment, but one each for the back feed side of the first rotary encoder 1 and the feed side of the second rotary encoder 2. The difference is that an optical sensor 13 as a first mark detection means and an optical sensor 26 as a second mark detection means are provided. The optical sensors 13 and 26 are the same as those in the first embodiment. Further, the difference is that a mark 55 is provided at a predetermined distance on the feed side of the joint 54.

In the figure, it is assumed that the belt 53 moves in the conveyance direction indicated by the arrow A. Further, in the drawing, “effective” is written for the rotary encoder that actually detects the feed amount of the belt 53.

In the state shown in FIG. 10A, the second rotary encoder 2 is selected by the switching unit 64 as an “effective” encoder. The correction unit 65 corrects the designated feed amount based on the detection signal from the second rotary encoder 2. The driver unit 62 drives the drive motor 61 with the corrected drive signal. In the state of FIG. 10A, the joint 54 on the belt 53 does not reach the second rotary encoder 2.

  When the conveyance of the belt 53 proceeds and the mark 55 provided in the vicinity of the joint 54 enters the detection position of the optical sensor 26 of the second rotary encoder 2 as shown in FIG. 55 is detected. Here, the distance x1 from the feed-side end of the joint 54 to the mark 55 is larger than the distance x2 between the second rotary encoder 2 (the central axis of the detection roller 21) and the optical sensor 26. Thereby, the optical sensor 26 can detect the mark 55 before the joint 54 enters the second rotary encoder 2.

The controller 63 controls the drive motor 61 based on the detection signal of the mark 55 to stop the belt 53. Then, the switching unit 64 switches the “valid” encoder from the second rotary encoder 2 to the first rotary encoder 1 based on the detection signal of the mark 55. When the encoder is switched, the correction unit 65 reads the individual error stored in the storage unit 66 shown in FIG. 3 and corrects the error.

Then, after switching from the second rotary encoder 2 to the first rotary encoder 1 and correcting the error required when the encoder is switched by the correction unit 65, the drive motor 61 is driven again to move the belt 53. The correction unit 65 corrects the designated feed amount based on the detection signal from the first rotary encoder 1. The joint 54 of the belt 53 passes through the second rotary encoder 2 as shown in FIG. 10C, but the detection signal from the second rotary encoder 2 is not used. There is no effect on the correction accuracy.

  Next, as shown in FIG. 10D, when the mark 55 of the joint 54 enters the detection position of the optical sensor 13 of the first rotary encoder 1 as the belt 53 moves, the optical sensor 13 sets the mark 55. To detect. Here, the distance x1 from the feed-side end of the joint 54 to the mark 55 is larger than the distance x3 between the first rotary encoder 1 (the central axis of the detection roller 11) and the optical sensor 13. Thereby, the optical sensor can detect the mark 55 before the joint 54 enters the first rotary encoder 1.

When the mark 55 is detected, the controller 63 controls the drive motor 61 to stop the belt 53. Then, the switching unit 64 switches the “valid” encoder from the first rotary encoder 1 to the second rotary encoder 2 based on the detection signal of the mark 55. When the encoder is switched, the correction unit 65 reads the individual error stored in the storage unit 66 and performs correction to fill it.

After the first rotary encoder 1 is switched to the second rotary encoder 2 and the correction unit 65 corrects an error required when the encoder is switched, the drive motor 61 is driven again to move the belt 53. The correcting unit 65 corrects the designated feed amount based on the detection signal from the second rotary encoder 2. The joint 54 of the belt 53 passes through the first rotary encoder 1 as shown in FIG. 10E, but the detection signal from the first rotary encoder 1 is not used. There is no effect on the correction accuracy.

  When the belt 53 moves only in the feed direction, the joint 54 makes one round between the first roller 51 and the second roller 52 wound by the movement of the belt 53, and as shown in FIG. The second rotary encoder 2 is reached again. Thereafter, the steps shown in FIGS. 10B to 10E are repeated.

  On the other hand, when the belt 53 back-feeds from the state shown in FIG. 10E, the second rotary encoder 2 is selected as the “effective” encoder in the state shown in FIG. For this reason, there is no problem even if the belt 53 is back-fed and the joint 54 passes through the first rotary encoder 1. On the other hand, when the mark 55 of the joint 54 enters the detection position of the optical sensor 13 of the first rotary encoder 1, the optical sensor 13 detects the mark 55. The detection of the mark 55 by the optical sensor 13 of the first rotary encoder 1 is the second time counting from the time of FIG.

The controller 63 determines the back feed of the belt 53 based on the detection signal of the mark 55 for the second time, and controls the drive motor 61 to stop the belt 53. Then, the switching unit 64 switches the “valid” encoder from the second rotary encoder 2 to the first rotary encoder 1 based on the detection signal of the mark 55. When the encoder is switched, the correction unit 65 reads the individual error stored in the storage unit 66 shown in FIG. 3 and corrects the error.

  The distance x1 from the feed-side end of the joint 54 to the mark 55 is larger than the distance x3 between the first rotary encoder 1 (the center axis of the detection roller) and the optical sensor 13.

Then, after switching from the second rotary encoder 2 to the first rotary encoder 1 and correcting the error required when the encoder is switched by the correcting unit 65, the drive motor 61 is again turned on as shown in FIG. The belt 53 is moved by driving. The correction unit 65 corrects the designated feed amount based on the detection signal from the first rotary encoder 1. Even if the joint 54 passes through the second rotary encoder 2 as it is, the detection signal from the second rotary encoder 2 is not used.

  As shown in FIG. 10H, when the belt 53 is back-fed as it is and the mark 55 enters the detection position of the optical sensor 26 of the second rotary encoder 2, the optical sensor 26 detects the mark 55. The controller 63 controls the drive motor 61 based on the detection signal of the mark 55 to stop the belt 53. Then, the switching unit 64 switches the “valid” encoder from the first rotary encoder 1 to the second rotary encoder 2 based on the detection signal of the mark 55. When the encoder is switched, the correction unit 65 reads the individual error stored in the storage unit 66 shown in FIG. 3 and corrects the error.

If the belt 53 is fed back in this state and the joint 54 makes one turn between the first roller 51 and the second roller 52, the mark 55 of the joint 54 is changed to the first rotary encoder as shown in FIG. 1 enters the detection position of the optical sensor 13, and the optical sensor 13 detects the mark 55. Based on this detection signal, the switching unit 64 switches from the second rotary encoder 2 to the first rotary encoder 1. After that, the same steps shown in FIGS. 8F to 8H are repeated.

  On the other hand, when the belt 53 reverses in the feed direction from the back feed state of FIG. 10G, the first rotary encoder 1 is selected as the “effective” encoder in the state shown in FIG. When the mark 55 of the joint 54 enters the detection position of the optical sensor 13 of the first rotary encoder 1, the optical sensor 13 detects the mark 55.

  Since the detection of the mark 55 by the optical sensor 13 when the first rotary encoder 1 is “valid” can be determined as the movement of the belt 53 in the feed direction, the controller 63 controls the drive motor 61 based on the detection signal of the mark 55. Then, the belt 53 is stopped. Then, the switching unit 64 switches the “valid” encoder from the first rotary encoder 1 to the second rotary encoder 2 based on the detection signal of the mark 55. When the encoder is switched, the correction unit 65 reads the individual error stored in the storage unit 66 shown in FIG. 3 and corrects the error.

  When the belt 53 moves in the feed direction and the joint 54 makes one round between the first roller 51 and the second roller 52, the second rotary encoder 2 is reached again as shown in FIG. Thereafter, the same steps as described above are repeated.

  That is, when the optical sensor 13 detects the mark 55 when the first rotary encoder 1 is “valid”, the switching unit 64 changes the “valid” encoder from the first rotary encoder 1 to the second rotary encoder 2. Switch. On the other hand, when the optical sensor 13 detects the mark 55 when the first rotary encoder 1 is not “valid” (when the second rotary encoder 2 is “valid”), the switching unit 64 selects the “valid” encoder. 2 Switch from the rotary encoder 2 to the first rotary encoder 1. When the optical sensor 26 detects the mark 55 when the second rotary encoder 2 is “valid”, the switching unit 64 changes the “valid” encoder from the second rotary encoder 2 to the first rotary encoder 1. Switch. On the other hand, when the optical sensor 26 detects the mark 55 when the second rotary encoder 2 is not “valid” (when the first rotary encoder 1 is “valid”), the switching unit 64 selects the “valid” encoder. The first rotary encoder 1 is switched to the second rotary encoder 2.

  In this way, the same effect as the belt type conveying apparatus 500 of the fifth embodiment can be obtained and only one mark 55 is required. In the above description, the optical sensor 13 is provided on the back feed side of the first rotary encoder 1 and the optical sensor 26 is provided on the feed side of the second rotary encoder 2. However, as shown in FIG. The optical sensors 16 and 23 may be provided on the feed side and the back feed side of the second rotary encoder 2.

  In the first to sixth embodiments, the mark 55 is a hole provided in the belt 53. However, the mark 55 may be a reflection mark 55 and an optical sensor may be provided on the front side of the belt 53 (not shown). Further, instead of the optical sensor, a roller plunger type limit switch that detects irregularities of the mark 55 such as a hole may be used.

(Embodiment 7)
FIG. 11 is a partial perspective view showing a belt-type conveyance device according to Embodiment 7 of the present invention. 12 is a side view showing the belt-type transport device shown in FIG. The belt-type conveyance device 200 includes a pair of protrusions 201 provided as opposed to each other as a holding means, and a cylindrical body 202 that supports the protrusions 201 in an axial direction. The protrusion 201 is urged toward the belt 53 by a spring (not shown) provided in the cylindrical body 202. The tip of the protrusion 201 is hemispherical and is surface-treated so as to be slidable with respect to the belt 53 with a low frictional force and difficult to wear. The tip shape of the protrusion 201 is not limited to a hemisphere. The protrusions 201 are provided on the inner and upper sides of a bracket 203 having a U-shaped cross section. The bracket 203 is fixed to a frame or the like (not shown) of the belt type conveyance device 200. As a result, the end portion of the belt 53 is sandwiched from the front and back by the protrusion 201. The tip of the protrusion 201 may be a rotatable ball or roller (not shown).

In addition, an absolute linear scale 204 having a predetermined pattern is provided at the end of the belt 53. Further, it is preferable that the linear scale 204 is provided so as to avoid a portion where the protrusion 201 slides. The belt 53 is not provided with the hole 55 as in the first to sixth embodiments. Similarly to the above, the belt 53 has a belt-like joint 54 having a certain width in a direction orthogonal to the transport direction.

A first optical sensor 205 is attached to the bracket 203. In other words, the first optical sensor 205 is provided in the vicinity of the protrusion 201 via the bracket 203. The first optical sensor 205 faces the linear scale 204 and is provided at a predetermined position so that the scale of the linear scale 204 can be read. The second optical sensor 206 is provided with a gap larger than the width of the joint 54 from the first optical sensor 205.

  In the belt-type transport device 200, the belt 53 is sandwiched by the protrusion 201 with a predetermined pressure, so that the vibration of the belt 53 when the belt 53 moves can be prevented. For this reason, since the distance between the first optical sensor 205 and the linear scale 204 is kept constant, the feed amount of the belt 53 can be accurately detected. Further, the switching unit (not shown, corresponding to the switching unit in FIG. 3) is based on the output signal of the first optical sensor 205 before the first optical sensor 205 is positioned on the joint 54. Switching from the first optical sensor 205 to the second optical sensor 206 is performed. The feed amount is detected by the second optical sensor 206 at least while the first optical sensor 205 is positioned on the joint 54. Then, when the first optical sensor 205 is no longer positioned on the joint 54, the second optical sensor 206 is switched to the first optical sensor 205. Note that the second optical sensor 206 is also provided with a sandwiching means composed of the projections 201 and the like as described above, thereby preventing vibration of the belt 53 in the vicinity of the second optical sensor 206 and a more precise feed amount. Can be detected.

  Further, as shown in FIG. 13, plate-like protrusions 251 having a circular tip from the inner upper and lower sides of the bracket 203 are provided facing each other, and the distance between the upper protrusion 251 and the lower protrusion 251 is set to the thickness of the belt 53. You may make it a little larger. The bracket 203 is configured so that the thickness variation of the belt 53 can be absorbed by elastic deformation by selecting the thickness, material, and the like. Even with the holding means having such a shape, the vibration of the belt 53 can be prevented, so that the same effect as described above can be obtained.

  In addition, the invention which concerns on the said Embodiment 1-7 can also be specified as follows.

  According to a first aspect of the present invention, there is provided a medium conveying device in which ends are joined together, a flexible belt provided with a mark avoiding the joined joint, and the belt feed in a state where the belt is always sandwiched. A first detection means for detecting the amount, a first mark detection means for detecting a mark on the belt corresponding to the first detection means, and the connection from the first detection means in a state where the belt is always held. A second detection means for detecting the feed amount of the belt provided with a gap larger than the width of the eye, and a belt feed amount detected by the first detection means; And detecting means for detecting the feed amount of the belt when the mark is detected, and switching means for switching from the first detecting means to the second detecting means.

  That is, in the present invention, the first mark detection means detects a mark provided avoiding the belt joint, and the second detection means is switched from the first detection means to the second detection means based on the detection of the mark. To detect the feed amount of the belt. Since the second detection means is provided with an interval larger than the width of the joint from the first detection means, when the first detection means is located on the joint, the second detection means is on the joint. Will not be located. Therefore, if the first detection means is switched to the second detection means based on the detection of the mark, the belt need not be detected at the joint portion of the belt. In this way, it is not necessary to correct an error due to a large thickness variation at the joint, so that the feed amount can be accurately detected.

Further, the detection means is configured to detect a feed amount in a state where the belt is always held, for example, a combination of a roller and a rotary encoder. The detection means having a structure that always holds the belt is used because it is suitable for detecting the feed amount of the flexible belt. For example, even if a scale is provided on a flexible belt and it is attempted to recognize the scale with a non-contact sensor, the scale cannot be read accurately due to bending due to vibration of the belt or the like, or elongation due to temperature change. On the other hand, if the feed amount is detected while the belt is always held, the actual feed amount of the belt can be accurately detected even if the belt is bent or stretched. The mark is, for example, a hole on a belt or a reflective material, and the first mark detection means is, for example, an optical sensor or a limit switch.

According to a second aspect of the present invention, there is provided the medium conveying apparatus according to the first aspect, wherein the switching means further includes the second detecting means when the belt moves by a predetermined switching feed amount after switching to the second detecting means. It is characterized by switching to one detection means.

  In this way, after the switching to the second detection means, if the detection means for detecting the feed amount of the belt is returned to the first detection means after the belt has moved by the switching feed amount, the joint will go around once. In the same way as described above, it is possible to prevent the feed amount from being detected at the joint portion by switching from the first detection means to the second detection means.

According to a third aspect of the present invention, there is provided a medium transporting apparatus according to the first aspect, further comprising second mark detecting means corresponding to the second detecting means for detecting the mark on the belt, wherein the switching means further includes: In the case where the feed amount of the belt is detected by the second detection means, the detection means for detecting the feed amount of the belt when the mark on the belt is detected by the second mark detection means, the second detection means To the first detection means.

  In this invention, the first mark detecting means and the second mark detecting means are provided in association with both the first detecting means and the second detecting means, and the first mark detecting means or the second mark detecting means on the belt. Based on the detection of the mark, the detection means is switched. As a specific example, in the case where the belt feed amount is detected by the second detection means, the detection means for detecting the belt feed amount when the mark on the belt is detected by the second mark detection means, When the belt is switched from the second detection means to the first detection means and the feed amount of the belt is detected by the first detection means, when the mark on the belt is detected by the first mark detection means, The detection means for detecting the feed amount is switched from the first detection means to the second detection means. Even in this case, it is not necessary to detect the feed amount of the belt at the joint portion of the belt, so that the feed amount can be accurately detected.

  In the medium conveying apparatus according to a fourth aspect of the present invention, in the third aspect of the invention, two marks are provided on both sides in the moving direction of the joint, avoiding the joint, and the first mark detection means includes: Two of the first detection means are provided on both sides of the belt movement direction, and two of the second mark detection means are provided on both sides of the second detection means of the belt movement direction.

  That is, in the present invention, two mark detection means are provided on both sides of the first detection means and the second detection means, respectively, and marks are provided on both sides of the joint. Switching between the first detecting means and the second detecting means is performed. As a specific example, in the case where the belt feed amount is detected by the second detection means, the detection means for detecting the belt feed amount when a mark on the belt is detected by one second mark detection means. Is switched from the second detecting means to the first detecting means, and when the belt feed amount is detected by the first detecting means, the mark on the belt is detected by one first mark detecting means. At this time, the detection means for detecting the feed amount of the belt is switched from the first detection means to the second detection means. The present invention is particularly useful in a cutting plotter that requires backfeed to cut the medium.

In the medium conveying apparatus according to a fifth aspect of the present invention, in the third aspect of the invention, two marks are provided on both sides in the moving direction of the joint, avoiding the joint, and the first mark detecting means is One interval is provided so that the interval from the first detection unit is smaller than the interval from the end of the joint to one mark, and the second mark detection unit has an interval from the second detection unit, One is provided so as to be smaller than the interval from the end of the joint to the other mark.

  That is, according to the present invention, if the distance from the detection means is smaller than the distance from the end of the joint to the mark, the feed amount is detected at the joint by the detection means in both the feed direction and the back feed direction. It is possible to detect the mark before switching and switch the detection means. As a specific example, in the case where the belt feed amount is detected by the second detection means, the detection means for detecting the belt feed amount when the mark on the belt is detected by the second mark detection means, When the belt is switched from the second detection means to the first detection means and the feed amount of the belt is detected by the first detection means, when the mark on the belt is detected by the first mark detection means, The detection means for detecting the feed amount is switched from the first detection means to the second detection means. In such a configuration, the number of parts can be reduced because only one mark detection means is provided for the detection means.

  A medium conveying apparatus according to a sixth invention is characterized in that, in the first to fifth inventions, an interval between the first detecting means and the second detecting means is half of the belt circumferential length.

  In this way, after the detection unit is switched by detecting the joint, the next switching is not performed unless the belt makes a half turn, so that the number of switching of the detection unit can be reduced. For this reason, processing time is shortened.

DESCRIPTION OF SYMBOLS 100 Belt type conveying apparatus 1 1st rotary encoder 2 2nd rotary encoder 13, 23, 16, 26 Optical sensor 51 1st roller 52 2nd roller 53 Belt 54 Joint 55 Mark 61 Drive motor 62 Driver unit 63 Controller 64 Switching part 65 Correction section

Claims (2)

A flexible belt with seams in the joined parts;
First detection means for detecting a feed amount of the belt in a state where the belt is always held by the holding means;
A second detection means for detecting a feed amount of the belt in a state where the belt is always held between the first detection means and a gap larger than a width of the joint;
In the case where the feed amount of the belt is detected by the first detection means, the detection means for detecting the feed amount of the belt before the first detection means is located on the joint, the first detection Switching means for switching from the means to the second detection means;
I have a,
The first detection means or the second detection means comprises a non-contact sensor that detects a detected part formed on the belt or a portion driven by the belt in a non-contact manner.
While providing a mark on the belt avoiding the seam,
A first mark detecting means provided corresponding to the first detecting means for detecting the mark on the belt;
Provided corresponding to second detection means, and provided with second mark detection means for detecting the mark on the belt,
The switching means switches the detection means for detecting the feed amount of the belt from the first detection means to the second detection means when the mark on the belt is detected by the first mark detection means,
Further, in the case where the feed amount of the belt is detected by the second detection means, the detection means for detecting the feed amount of the belt when the mark on the belt is detected by the second mark detection means, A medium conveying apparatus characterized by switching from the detecting means to the first detecting means . Wherein the first detecting means the distance between the second detecting means, the medium conveying device according to claim 1, characterized in that the half of the belt perimeter.

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