JP2005306491A - Double feed detection device, composite treatment device and the threshold value setting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To set a threshold value in order to accurately detecting double feeding without performing erroneous detection even when high dispersion exists in thickness of paper and even when high dispersion exists in sensor sensitivity. <P>SOLUTION: The composite treatment device 1 has a paper thickness sensor 40 (paper thickness detection part) for detecting thickness of the paper conveyed on a first paper conveying passage P1; a paper thickness comparison part 61 for comparing output of the paper thickness sensor with the threshold value Th; a double feed determination part 62 for performing determination of double feeding based on the comparison result of the paper thickness comparison part 61; and a threshold value operation part 63 for operating the threshold value Th. The threshold value operation part 63 determines a characteristic linear line (characteristic function) of the paper thickness sensor 40 based on the output of the paper thickness sensor 40 when a gauge sheet GS (reference paper) having reference thickness is inserted and operates an upper limit and a lower limit of the threshold value Th using the characteristic linear line to operate the threshold value Th. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a double feed detection device, a composite processing device, and a threshold setting method.

  2. Description of the Related Art Conventionally, various apparatuses that convey sheets such as cut sheets one by one are sometimes provided with a double feed detection device that measures the thickness of a conveyed sheet and detects double feeding of sheets.

  As an example of a double feed detection device, a reflective sensor is disposed in the vicinity of a paper guide that defines a paper transport path, and light reflected by the surface of the paper is received by this reflective sensor to directly increase the paper thickness of the paper. A double feed detection device that detects and detects double feed of paper has been proposed (see Patent Document 1).

  Also, a double feed detection device that detects a double feed of paper by arranging a lever on the roller shaft of the paper transport roller and detecting the displacement of the lever due to the paper thickness with an optical sensor or the like has been proposed (Patent Document 2). reference).

Further, in the double feed detection device, one sheet of paper to be actually processed is transported and a paper thickness is measured by a paper thickness sensor to determine a threshold value. Has been proposed (see Patent Document 3).
Japanese Patent No. 3421104 JP 60-144256 A JP 7-215538 A

In the above-described multifeed detection device, when a sheet having a predetermined threshold value and having a sheet thickness equal to or greater than the threshold value is detected, at least two sheets of the sheet are double-fed. Judge that
However, in this type of multifeed detection device, if there is a large variation in the thickness of the transported paper, the difference in thickness between the transport of one sheet and the transport of two sheets will be small, so an appropriate threshold value is used. If it is not set, there may be a case where it is determined that double feeding is being performed even though only one sheet is being transported, or that one sheet is transported even though two sheets are being transported. In addition to variations in paper thickness, in the case of paper such as a check, if there is a crease, wrinkle, dirt, etc., if the first check is used as a criterion for multi-feed judgment, there will be variations in judgment criteria. It can become large and lead to false detection.

  In general, the sensor for detecting the paper thickness has a variation in sensor sensitivity for each sensor, and it is difficult to give a uniform threshold value to all the multifeed detection devices. If a predetermined threshold value is given to all double feed detection devices, it is erroneously detected as double feed even though all double feed detection devices carry one sheet of the same thickness. There is also a possibility that a double feed detection device for detection will come out.

  The present invention has been made in view of the above. Even if the thickness of the paper has a large variation or the sensitivity of the sensor has a large variation, the present invention can be accurately duplicated without erroneous detection. It is an object of the present invention to provide a double feed detection device, a composite processing device, and a threshold setting method capable of detecting a feed.

The above object of the present invention is achieved by the following means.
(1) a paper thickness detection unit that detects the thickness of the paper conveyed on the paper conveyance path;
A paper thickness comparison unit that compares the output of the paper thickness detection unit with a threshold value;
A double feed determination unit that performs double feed determination based on a comparison result of the paper thickness comparison unit;
A threshold value calculation unit for calculating the threshold value,
The threshold value calculating unit calculates a threshold value of the paper thickness detecting unit based on an output of the paper thickness detecting unit when a reference sheet having a reference thickness is inserted. apparatus.
(2) The threshold value calculation unit is configured to output the threshold value based on the output of the paper thickness detection unit when no paper is present and the output of the paper thickness detection unit when the reference paper is inserted. The multifeed detection device according to (1), wherein
(3) The threshold value calculation unit obtains a characteristic function of the paper thickness detection unit based on an output of the paper thickness detection unit when a reference sheet having a reference thickness is inserted, and uses the characteristic function. And calculating the upper and lower limits of the threshold value to calculate the threshold value.
(4) The threshold value calculation unit calculates the characteristic function based on the output of the paper thickness detection unit when there is no paper and the output of the paper thickness detection unit when the reference paper is inserted. The multifeed detection device according to (3), wherein the multifeed detection device performs calculation.
(5) According to (3) or (4), the threshold value calculation unit calculates an upper limit and a lower limit of the threshold value with reference to the maximum thickness and the minimum thickness of the conveyed paper. The double feed detection device described.
(6) The threshold is based on the thickness of one of the thickest paper among the transported paper and the thickness of two of the thinnest paper among the transported paper, The double feed detection device according to any one of (3) to (5), wherein a lower limit is calculated.
(7) The double feed detection according to any one of (3) to (6), wherein the threshold is an intermediate value between an upper limit of the threshold and a lower limit of the threshold apparatus.
(8) A printer including the double feed detection device according to any one of (1) to (7).
(9) A composite processing apparatus comprising the double feed detection device according to any one of (1) to (7).
(10) A reference thickness detection step for obtaining an output of the paper thickness detection unit corresponding to a reference thickness by inserting a reference sheet having a reference thickness into a paper conveyance path provided with a paper thickness detection unit;
A threshold value calculating step for calculating a threshold value for multifeed determination based on the output obtained in the reference thickness detecting step,
The threshold value setting method, wherein the threshold value calculating step obtains a threshold value based on an output of the paper thickness detection unit.
(11) The threshold value calculation unit is configured to output the threshold value based on the output of the paper thickness detection unit when no paper is present and the output of the paper thickness detection unit when the reference paper is inserted. (10) The threshold value setting method according to (10).
(12) The threshold value calculating step calculates a characteristic function of the paper thickness detection unit based on an output of the paper thickness detection unit, and calculates an upper limit and a lower limit of the threshold value using the characteristic function. The threshold value setting method according to (10), wherein the threshold value is calculated.
(13) In the threshold value calculating step, the characteristic function is calculated based on an output of the paper thickness detection unit when there is no paper and an output of the paper thickness detection unit when the reference paper is inserted. The threshold value setting method according to (12), wherein the threshold value is calculated.
(14) In the threshold value calculating step, the upper limit and the lower limit of the threshold value are calculated with reference to the maximum thickness and the minimum thickness of the conveyed paper. The threshold setting method described.
(15) The threshold value is an upper limit of the threshold value based on the thickness of one of the thickest paper among the transported papers and the thickness of the two thinnest papers among the transported papers. The threshold value setting method according to any one of (12) to (14), wherein a lower limit is calculated.
(16) The threshold value according to any one of (12) to (15), wherein the threshold value is an intermediate value between an upper limit value of the threshold value and a lower limit value of the threshold value. Setting method.

  According to the present invention, the threshold value is calculated based on the output of the paper thickness detector when a reference sheet having a reference thickness is inserted. Therefore, according to the present invention, it is possible to set a threshold value in consideration of variations in sensor sensitivity in consideration of variations in sensor sensitivity between the paper thickness detection units provided in each double feed detection device. Become. Therefore, if the sheets have the same thickness, it is possible to make a uniform judgment in all the multifeed detection devices, and it is possible to provide an easy-to-handle doublefeed detection device and a composite processing device that do not cause a false detection. It becomes possible.

  According to the present invention, the characteristic function of the paper thickness detection unit is obtained based on the output of the paper thickness detection unit, and the upper and lower limits of the threshold value are calculated using the characteristic function to calculate the threshold value. It is configured to be. Therefore, even when a plurality of sheets with large thickness variations between sheets are conveyed continuously, the threshold is set after the upper and lower thresholds are obtained. Therefore, the threshold value can always be set in an appropriate area.

  Specifically, in the present invention, referring to the maximum thickness and the minimum thickness of the transported paper, more specifically, the thickness of one of the thickest paper among the transported paper and the transported paper The upper limit and the lower limit of the threshold value are calculated based on the thickness of the two thinnest sheets, so that the variation range for one sheet and the variation range for two sheets are as follows. A threshold can be set between Therefore, it is possible to provide an effective double feed detection device, a composite processing device, and a threshold setting method that do not cause erroneous detection depending on variations in sheet thickness.

  In the present invention, a characteristic function of the paper thickness detection unit is calculated based on an output of the paper thickness detection unit when a reference sheet having a reference thickness is inserted, and a threshold value is obtained based on the characteristic function. It is configured as follows. Therefore, according to the present invention, the sensor sensitivity between the paper thickness detection units provided in each double feed detection device is expressed as a characteristic function, and the threshold value is obtained based on this characteristic function. It is possible to perform threshold setting in view of the above. Therefore, if the sheets have the same thickness, it is possible to make a uniform judgment in all the multifeed detection devices, and it is possible to provide an easy-to-handle doublefeed detection device and a composite processing device that do not cause a false detection. It becomes possible.

  Next, an embodiment of a composite processing apparatus (printer) provided with a double feed detection apparatus according to the present invention will be described in detail with reference to the drawings.

(About compound processing equipment)
FIG. 1 is a perspective view showing an embodiment of a combined processing apparatus according to the present invention, FIG. 2 is a schematic view showing a sheet conveyance path in the combined processing apparatus, and FIG. 3 is an internal structure of the combined processing apparatus. FIG. 4 and FIG. 5 are perspective views of the composite processing apparatus with the housing removed.

  As shown in FIG. 1, the composite processing apparatus 1 according to the present embodiment conveys a check CK loaded in the paper feeding unit 3 along the first paper conveyance path P1 formed in the housing 1a, while checking CK. The upper double-sided image is read, the magnetic character on the check CK is read, and the endorsement printing on the check CK is executed to be discharged from the discharge port 4. Further, the composite processing apparatus 1 can execute reading of a double-sided image on the card C while transporting the card C inserted from the card insertion slot 20 along the paper transport path P2 formed in the housing 1a. It is configured.

The composite processing apparatus 1 also includes a roll paper storage section 28a (not shown) for storing roll paper (not shown) in a lower portion of a roll paper cover 28 provided in the central portion of the housing 1a surrounded by the first paper transport path P1. 4). The roll paper stored in the roll paper storage unit 28a is configured to be printable by the print head 15 described later. The printed roll paper is discharged from the roll paper discharge port 29 to the outside of the combined processing apparatus 1.
That is, the composite processing apparatus 1 reads the image on the check CK while reading the check CK while conveying the check CK along the first paper conveyance path P1, reads the magnetic character printed on the check CK, and prints on the check CK. And an image reading device / magnetic character reading device / printing device capable of reading an image on the card C and printing on a roll paper while conveying the card C along the paper conveyance path P2. is there.

First, a specific structure of the composite processing apparatus 1 will be described.
As shown in FIG. 2, the first paper transport path P <b> 1 has a substantially U shape, and the second paper transport path P <b> 2 has a linear shape for transporting the card C. The first paper transport path P1 and the second paper transport path P2 are common in a portion corresponding to the bottom portion of the U shape, and this portion will be referred to as an intermediate transport path M in the following description. Various reading devices are provided in the intermediate conveyance path M. Details of the various reading devices will be described later.

  As shown in FIG. 2, the first paper transport path P1 is composed of an outer guide 2a and an inner guide 2b, and the check CK is transported into a transport section 2c that is a space between the outer guide 2a and the inner guide 2b. It is configured to be. The check CK is inserted into the first paper transport path P1 via the paper feed unit 3 from the direction of arrow A in FIG. The paper feed unit 3 is configured to be able to load a plurality of checks CK, and can send out the plurality of checks CK one by one into the first paper transport path P1.

The first paper transport path P1 has a first transport roller 6 upstream of the intermediate transport path M, an intermediate transport roller 16 in the intermediate transport path M, and an intermediate transport path M as a transport mechanism for transporting the check CK. The 2nd conveyance roller 7 is provided in the downstream of this.
The first transport roller 6 includes a drive roller 6a and a pressing roller 6b disposed to face the drive roller 6a via the first paper transport path P1. The second transport roller 7 includes a drive roller 7a and a pressing roller 7b disposed to face the drive roller 7a via the first paper transport path P1.
Further, as shown in FIG. 3, the intermediate conveying roller 16 includes a lower pressing roller 16b disposed below the first sheet conveying path P1, an upper pressing roller 16a disposed above the lower pressing roller 16b, and an intermediate pressing roller 16b. The upper presser roller 16a and the lower presser roller 16b are disposed to face the upper presser roller 16a via the transport path M.

As shown in FIG. 3, the check CK fed into the first paper transport path P1 is transported through the intermediate transport path M by the first transport roller 6, the intermediate transport roller 16, and the second transport roller 7, and is discharged. It is discharged from the discharge port 4 in the direction of arrow B through the roller 8. In the present embodiment, as shown in FIG. 4, the bottom position of the first paper transport path P1 is maintained at the height H1, and the check CK is the bottom of the first paper transport path P1 including the intermediate transport path M. Are conveyed in a state based on the height H1.
Here, regarding the intermediate conveyance roller 16, if the width (height) of the check CK is shorter than a predetermined length, the lower presser roller 16b and the driving roller 17 contribute to the conveyance of the check CK, while the width of the check CK is a predetermined length. If it is more than that, the check CK is conveyed by both the upper pressing roller 16 a and the lower pressing roller 16 b and the driving roller 17.

  On the other hand, as shown in FIGS. 2 and 3, the second paper transport path P2 includes an intermediate transport path M, and a card insertion slot 20 and a card reverse path 21 communicating with both ends thereof.

  The card insertion slot 20 is an insertion slot for inserting the card C into the intermediate transport path M. Below the card insertion slot 20, as shown in FIGS. 3 and 4, lower guides 24 and 24a are provided. The lower guides 24 and 24a constitute a part of the outer guide 2a, and the height of the lower end portion of the card C is kept at H2. The card C is guided by the lower guide 24 and enters the intermediate transport path M. Inserted and transported in a state based on the height H2. That is, the lower position of the second paper transport path P2 is maintained at the height H2 with respect to the lower guides 24 and 24a. Note that the check CK, which is kept at the height H1 and is conveyed along the first paper conveyance path P1, is bent toward the discharge port 4 by the lower guide 24a.

  The upper presser roller 16a is mounted above the height H2 of the second paper transport path P2, and the card C transported into the intermediate transport path M is intermediately transported by the upper presser roller 16a and the drive roller 17. It is conveyed in the path M.

  The card reverse path 21 is formed by linear guides 21a and 21b formed along the left extension line of the intermediate conveyance path M in FIG. In the vicinity of the end 21c of the card reverse path 21, a forward / reverse conveyance roller 22 is provided. The forward / reverse conveyance roller 22 conveys the card C conveyed from the intermediate conveyance path M so as to protrude from the end 21c of the card reverse rotation path 21 for a predetermined length, and again the card C protruding from the end 21c. Transport to the intermediate transport path M.

  Specifically, when the card C is inserted into the intermediate transport path M from the card insertion port 20, the card C is transported to the card reverse path 21 by the upper pressing roller 16 a and the driving roller 17. Then, the card C is reversely conveyed from the card reverse path 21 by the forward / reverse conveyance roller 22, passes through the intermediate conveyance path M, and is discharged from the card insertion slot 20. At this time, the card C is transported in the second paper transport path P2 with the lower end portion maintained at the height H2. In the present embodiment, the height H2 of the second paper transport path P2 is arranged at a position higher than the height H1 of the first paper transport path P1. In summary, the card C is transported through the intermediate transport path M above the check CK.

  As described above, in the present embodiment, by changing the conveyance height of the check CK and the card C, a U-shaped first sheet conveyance path and a straight second line can be provided without providing a special switching device or the like. Different types of reading media can be transported to the paper transport path. This completes the description of the conveyance of the check CK and the card C.

  In the intermediate conveyance path M, a first image reading sensor 11 and a second image reading sensor 12 that perform image reading are installed. Each of the first image reading sensor 11 and the second image reading sensor 12 is a CIS (Contact Image Sensor) type image reading sensor, and emits light to one surface of the check CK or the card C conveyed on the intermediate conveyance path M. Irradiate and receive light reflected on check CK or card C. The first image reading sensor 11 and the second image reading sensor 12 read the image on the check CK or the card C conveyed in the intermediate conveyance path M line by line, so that the two-dimensional of the check CK or the card C is obtained. Get an image.

  A BOF (Bottom Of Form) detector 9 and a TOF (Top Of Form) detector 10 for detecting the trailing edge of the check CK are provided in the first paper transport path P1. The BOF detector 9 is provided between the paper feed unit 3 and the first transport roller 6, detects the check CK inserted from the paper feed unit 3, and when the check CK passes through the BOF detector 9 And the trailing edge of the check CK is detected. The TOF detector 10 is provided between the first transport roller 6 and the first image reading sensor 11, and is configured to detect the tip of the check CK. Thus, the length of the check CK can be accurately measured by detecting the leading edge and the trailing edge of the check CK with the BOF detector 9 and the TOF detector 10. The composite processing apparatus 1 according to the present embodiment is configured to operate according to the check CK detection by the BOF detector 9 and the TOF detector 10. That is, the start / stop of the reading of the check CK by the image reading sensors 11 and 12 is controlled based on the outputs of the BOF detector 9 and the TOF detector 10. Note that one of the image reading sensors 11 and 12 may be used as a detector for detecting the tip of the check CK. In this case, the TOF detector 10 can be omitted.

  In addition, the print head 14 is disposed in a linear region between the second transport roller 7 and the discharge roller 8 and along the first paper transport path P1. The print head 14 is for executing endorsement on the check CK, and performs printing on the check CK as necessary.

  Further, a BOC (Bottom Of Card) detector 25 and a TOC (Top Of Card) detector 26 for detecting the rear end of the card C are provided in the second paper transport path P2. The BOC detector 25 is provided in the vicinity of the card insertion slot 20, detects the card C inserted from here, detects the time when the card C passes through the BOC detector 25, and detects the rear end of the card C. Is detected. The TOC detector 26 is provided between the intermediate conveyance roller 16 and the second image reading sensor 12 and is configured to detect the leading end of the card C. Thus, the length of the card C can be accurately measured by detecting the leading edge and the trailing edge of the card C by the BOC detector 25 and the TOC detector 26. The composite processing apparatus 1 of this embodiment is configured to operate in response to the detection of the card C by the BOC detector 25 and the TOC detector 26. That is, the start / stop of reading of the card C by the image reading sensor 11 or 12 is controlled based on the outputs of the BOC detector 25 and the TOC detector 26. Note that either one of the image reading sensors 11 and 12 may be used as a detector for detecting the leading end of the card C. In this case, the TOC detector 26 can be omitted.

  A MICR (Magnetic Ink Character Reader) 13 is installed below the drive roller 17. The MICR 13 is a sensor for reading information written in magnetic ink on the check CK. The MICR 13 performs reading in a state where the check CK is pressed against the surface of the MICR 13 by the pressing lever 30 disposed opposite to the MICR 13 via the intermediate conveyance path M.

(Structure of double feed detector)
FIG. 6 is a schematic diagram showing the double feed detection device 50 of the present embodiment.
As shown in FIG. 6, the double feed detection device 50 has the pressing lever 30 described above. The pressing lever 30 has a main body 31 which is a longitudinal member, and rotates in a plane perpendicular to the check conveyance surface of the intermediate conveyance path M via a rotation shaft 32 provided at one end of the main body 31. It is possible to move. The main body 31 is integrally formed with a pressing projection 33 projecting toward the intermediate conveyance path, and the pressing projection 33 is biased toward the MICR 13 by a biasing force by a pressing spring (not shown), and there is no check CK. In this state, the surface 13a of the MICR 13 and the contact surface 33a of the pressing protrusion 33 are in contact with each other.

  In the present embodiment, the contact surface 33 a of the pressing protrusion 33 is formed of a rigid body that is not displaced or deformed by the pressing of the pressing protrusion 33. The main body portion 31 of the pressing lever 30 is in a state where the longitudinal direction of the main body portion 31 is substantially parallel to the intermediate conveyance path M that conveys the check CK, with the tip end surface 33a of the pressing projection 33 in contact with the MICR 13. Always fixed.

  Further, the other end of the main body 31 is bent by approximately 90 degrees on the side opposite to the intermediate conveyance path M to form a bent portion 34. A paper thickness sensor 40 is disposed at a position facing the end surface 34a of the bent portion 34 at a predetermined distance.

  The paper thickness sensor 40 is a sensor that detects the displacement of the end surface 34a of the bent portion 34 that is a detection surface. For example, by irradiating the end surface 34a with light and receiving the reflected light on the light receiving surface 40a, It is an optical sensor that measures the distance.

The pressing protrusion 33 detects the distance L1 from the rotation center of the rotating shaft 32 to a straight line passing through the tip of the pressing protrusion 33 and parallel to the protruding direction of the pressing protrusion 33, and the end surface 34a of the bent portion 34 from the rotating center of the rotating shaft 32. The relationship with the distance L2 to the straight line passing through the part and parallel to the protruding direction of the pressing protrusion 33 is formed so as to satisfy the following.

L2 = L1 × N (N> 1) (1)
That is, L2> L1 (2)

In this embodiment, as shown in Formula (2), the pressing lever 30 is formed so that the distance L2 is longer than the distance L1.

  In the present embodiment, as shown in FIG. 6, the multi-feed detection device 50 is configured by the MICR 13, the pressing lever 30, and the paper thickness sensor 40. Hereinafter, the operation of the double feed detection device 50 will be described with reference to FIGS. 7 (a) and 7 (b).

FIG. 7A is a diagram showing a state in which a single check CK is transported in the intermediate transport path M (normal state), and FIG. 7B is a diagram in which two of check CK1 and check CK2 overlap. FIG. 8 is a diagram illustrating a state (multi-feed state) in which the inside of the intermediate transport path M is transported.
As shown in FIG. 7A, when one check CK is transported in the intermediate transport path M and transported between the MICR 13 and the pressing protrusion 33 of the pressing lever 30, the pressing lever 30 is turned into the check. According to the thickness d of CK, the pressing protrusion 33 is pushed back against the urging force of the pressing spring, and the pressing lever 30 rotates (in FIG. 7A, it rotates clockwise).

When the pressing lever 30 rotates, the end surface 34a of the pressing lever 30 is displaced, and the paper thickness sensor 40 detects the distance between the end surface 34a and the detection surface 40a of the paper thickness sensor 40. Here, the displacement amount D1 of the end surface 34a of the pressing lever 30 changes according to the distance L1 and the distance L2, and is configured to satisfy the following relationship.

D1≈d × (L2 / L1) (3)

That is, the displacement amount D1 of the end surface 34a of the pressing lever 30 is larger than the thickness d of the check CK disposed between the MICR 13 and the pressing protrusion 33 of the pressing lever 30. The paper thickness sensor 40 detects the displacement amount D1, and the combined processing apparatus 1 determines that only one check CK is being conveyed.

  On the other hand, as shown in FIG. 7 (b), the two checks CK1 and the check CK2 are transported in the intermediate transport path M with at least partly overlapped, and between the MICR 13 and the pressing protrusion 33 of the pressing lever 30. , The pressing lever 30 is pushed back against the urging force of the pressing spring according to the overlap thickness 2d of the checks CK1 and CK2, and the pressing lever 30 rotates (FIG. 7). (B) rotates clockwise). The amount of rotation of the pressing lever 30 is larger than when only one check CK is conveyed.

When the pressing lever 30 rotates, the end surface 34a of the pressing lever 30 is displaced, and the paper thickness sensor 40 detects the distance between the end surface 34a and the detection surface 40a of the paper thickness sensor 40. Here, the displacement amount D2 of the end surface 34a of the pressing lever 30 changes according to the distance L1 and the distance L2, and is configured to satisfy the following relationship.

D2≈2d × (L2 / L1) (4)
D2≈2D1 (5)

  That is, the displacement amount D2 of the end surface 34a of the pressing lever 30 is larger than the overlap thickness 2d of the checks CK1 and CK2 passing between the MICR 13 and the pressing protrusion 33 of the pressing lever 30, and of course only one check CK passes. It will be displaced more than if you do. The paper thickness sensor 40 detects the amount of displacement D2, so that the composite processing apparatus 1 determines that two checks CK are being conveyed, that is, the checks CK are being double-fed.

(Control of double feed detection and threshold setting: 1)
Next, an embodiment of control related to double feed detection of the composite processing apparatus 1 including the double feed detection device 50 of the present embodiment will be described.

FIG. 8 is a control block diagram showing double feed control using the double feed detection device 50.
The double feed detection device 50 according to this embodiment includes a paper thickness sensor 40 that detects the thickness of the check CK that is transported on the first paper transport path P1, and a sensor signal that is output from the paper thickness sensor 40. A D converter 41, a volatile RAM 42 in which a digital signal indicating a paper thickness value output from the A / D converter 41 (hereinafter referred to as a paper thickness detection value) is stored, and a predetermined threshold Th are held. A non-volatile flash ROM 48, a control unit 60 that performs general control, and a paper transport unit 90 that includes transport rollers 6, 7, and 8 that transport the check CK, a drive motor (not shown), and the like. .

  The control unit 60 includes a paper thickness comparison unit 61 that compares a paper thickness signal with a predetermined threshold Th, a multifeed determination unit 62 that performs multifeed determination based on the comparison result of the paper thickness comparison unit 61, A threshold value calculation unit 63 that calculates the threshold value Th, a sampling pulse generation unit 70, a motor driver 85 that sends a drive signal to the paper conveyance unit 90, and the like are included.

  The sampling pulse generator 70 is a circuit that generates a sampling pulse for operating the paper thickness sensor 40 and outputs the sampling pulse to the paper thickness sensor 40. The paper thickness sensor 40 is a sensor signal corresponding to the amount of displacement of the end face 34a of the pressing lever 30 (actually, the distance between the end face 34a and the paper thickness sensor 40) according to the sampling pulse from the sampling pulse generator 70. Is output to the A / D converter 41. The A / D converter 41 A / D converts the sensor signal output from the paper thickness sensor 40 and generates a digital paper thickness detection value corresponding to the sensor signal. The generated paper thickness detection value is sent to the RAM 42 and stored in the data buffer 45 in the RAM 42.

  The paper thickness comparison unit 61 compares the paper thickness detection value stored in the data buffer 45 of the RAM 42 with the threshold value Th stored in the flash ROM 48, and the paper thickness detection value is equal to or less than the threshold value Th. Determine if there is. Then, the paper thickness comparison unit 61 outputs a paper thickness abnormality signal to the double feed determination unit 62 if the detected paper thickness value is larger than the threshold value Th.

  Based on the notification from the paper thickness comparison unit 61, the double feed determination unit 62 determines whether or not there is a double feed. Specifically, when a notice of paper thickness abnormality is received from the paper thickness comparison unit 61, it is determined that double feed has occurred, and a double feed detection signal is output. In the case of this embodiment, it is automatically determined to be double feed only by notification of an abnormal paper thickness. Whether to double feed or not is determined in consideration of the above conditions. If the determination of double feeding is made, error processing such as stoppage of paper conveyance, lighting of a warning lamp, and output of a warning sound is performed based on this determination.

  The threshold value calculation unit 63 is a threshold value generation unit that generates a threshold value Th referred to by the paper thickness comparison unit 61. The multifeed detection device 50 according to the present embodiment includes a threshold setting mode for changing the setting of the threshold Th based on a reference sheet having a predetermined thickness. The threshold value can be set by operation. The composite processing apparatus 1 shifts to this threshold setting mode when a DIP switch (not shown) is operated or a mode shift command is received from an external host computer.

Specifically, in the threshold setting mode, as shown in FIG. 9, a gauge sheet (reference sheet) GS having a predetermined reference thickness t ₀ is inserted into the first sheet conveyance path P 1, and the sheet thickness sensor 40 The paper thickness detection value corresponding to the reference thickness t ₀ of the gauge sheet GS is detected.

Then, the threshold value calculation unit 63 and the paper thickness reference value corresponding to the reference thickness t ₀ and the paper of the paper thickness sensor 40 in a state where no paper such as a gauge sheet GS and a check exists in the first paper transport path P1. The threshold value Th is calculated based on the thickness reference value.

In the present embodiment, the threshold value calculation unit 63 is configured to detect variations in sensitivity characteristics between the paper thickness sensors 40 attached to the composite processing apparatus 1 and variations in the paper thickness t (check thickness) between conveyed sheets. Considering this point, the threshold value Th is set by the following method. In the following description, the thickness of the thinnest paper to be allowed among the thickness variations of the actually conveyed paper is assumed to be t _min, and the thickness of the thinnest paper to be allowed is assumed to be t _max .

(1) Measurement of paper thickness sensor sensitivity First, the sensor sensitivity of the paper thickness sensor 40 is measured. Specifically, the paper thickness reference value V1 when there is no paper (paper thickness = 0, that is, the distance d1 from the end face 34a to the paper thickness sensor 40), and the state where the gauge sheet GS is inserted (paper thickness = t ₀ , That is, a paper thickness reference value V2 at a distance d2) from the end face 34a to the paper thickness sensor 40 is obtained, a characteristic straight line E passing through the two coordinates (d1, V1), (d2, V2) obtained is calculated, and the sensor sensitivity is calculated. A slope α and an intercept β are obtained. Specifically, the slope α and the intercept β are given by the following equations (6) and (7).

α = (V2−V1) / (d1−d2) (6)
β = V1-α · d1 (or V2-α · d2) (7)

  FIG. 10A is a graph showing this characteristic line E. FIG. In FIG. 10A, the characteristic line E is sandwiched between regions indicated by a broken line between the characteristic line Emax and the characteristic line Emin. The characteristic straight line Emax is a straight line that can be drawn in the case of the paper thickness sensor having the highest sensitivity among the paper thickness sensors used in the combined processing apparatus and V2-V1 having the largest paper thickness detection value. On the other hand, the characteristic straight line Emin is a straight line that can be drawn in the case of the paper thickness sensor having the lowest sensitivity among the paper thickness sensors used in the combined processing apparatus and V2-V1 having the smallest paper thickness detection value. It is.

  The characteristic straight line Emax and the characteristic straight line Emin are characteristic straight lines in the case of the paper thickness sensor having the largest variation, and all the paper thickness sensors should be expressed as straight lines in a region between the characteristic straight line Emax and the characteristic straight line Emin. Can do. Thus, in this embodiment, the variation in sensitivity of the paper thickness sensor 40 is expressed as a characteristic line so that the threshold Th is set after the variation in sensitivity of the paper thickness sensor 40 is recognized. Has been.

(2) Determination of threshold value Next, the threshold value calculation unit 63 determines the threshold value Th using the slope α of the straight line E. Even if the same standard paper is used for the actual transport, there is some variation in thickness and the characteristic line of the paper thickness sensor has a certain degree of freedom. It is necessary to obtain a threshold value Th that can reliably detect double feeding regardless of the variation in the number and the degree of freedom of the characteristic line.
In the present embodiment, the influence of the variation in the sheet thickness and the degree of freedom of the characteristic line is removed as follows.

(A) The paper thickness value V3 at the detection position (distance between the end surface 34a and the paper thickness sensor 40 = d3) corresponding to the thickness tmax of the thickest paper among the transported paper is obtained from the characteristic line E. Specifically, the paper thickness value V3 is given by the following formula (8) as an example.

V3 = α · d3 + β
= Α · d3 + V1−α · d1
= Α · (d3−d1) + V1
= (V2-V1). (D3-d1) / (d1-d2) + V1 (8)

(B) Next, the detection position (distance between the end face 34a and the paper thickness sensor 40 = d4) corresponding to twice the thickness tmin of the thinnest paper among the conveyed paper is characterized by the paper thickness value V4. Obtained from the straight line E. Specifically, the paper thickness value V4 is given by the following formula (9) as an example.

V4 = α · d4 + β
= Α · d4 + V1−α · d1
= Α · (d4−d1) + V1
= (V2-V1). (D4-d1) / (d1-d2) + V1 (9)

Here, the paper thickness value V3 is a paper thickness value when the thickest paper is double fed when the paper thickness sensor 40 having the characteristic straight line E is used. On the other hand, the paper thickness value V4 is a paper thickness value when the thinnest paper is double fed when the paper thickness sensor 40 having the characteristic straight line E is used. Therefore, the double feed detection device 50 of the present embodiment must determine that there is no double feed when the paper thickness detection value V3, while it needs to determine that double feed is present when the paper thickness detection value V4. is there. That is, the paper thickness value V3 and the paper thickness value V4 correspond to the lower limit value and the upper limit value of the threshold Th, respectively. Therefore, the threshold value Th to be set is given by the following equation (10).

V3 <Th <V4 (10)

That is, as shown in FIG. 10B, the threshold value calculation unit 63 is larger than the paper thickness value V3 that is the lower limit value of the threshold value Th and from the paper thickness value V4 that is the upper limit value of the threshold value Th. Is set as the threshold value Th. By setting in this way, even if the assumed thinnest sheet is transported two sheets, it is possible to reliably detect double feeding, while when the assumed thickest sheet is transported one sheet It can be determined that it is not sent.
Theoretically, there is no problem as long as the expression (10) is satisfied. However, in the actual measurement, since it is assumed that the detection value varies, the threshold Th is the variation in the detection value. For example, it is preferable to set to an intermediate value between the paper thickness value V3 and the paper thickness value V4.

  Note that the thickness tmax of the thickest paper to be conveyed and the thickness tmin of the thinnest paper may be written in the flash ROM 48 in advance, and every time the type (namely, thickness) of the paper to be conveyed is changed. Alternatively, the values of the thickness tmax and the thickness tmin of the thinnest paper conveyed from the host computer may be received, and the data in the flash ROM may be rewritten. In the following description, it is assumed that the thickness tmax of the thickest sheet conveyed in advance in the flash ROM 48 and the thickness tmin of the thinnest sheet are written.

  Next, the flow of threshold setting processing in the composite processing apparatus 1 of this embodiment will be summarized with reference to the flowchart shown in FIG.

  First, for example, after operating a predetermined DIP switch provided in the composite processing apparatus 1, the threshold setting mode is started by restarting the composite processing apparatus 1 (step S1). First, the composite processing apparatus 1 outputs a sampling pulse from the sampling pulse generator 70 to the paper thickness sensor 40 in a state where the gauge sheet GS and the paper (check CK) are not present in the first transport path P1, and the paper The thickness sensor 40 is made to detect the paper thickness detection value V1 when there is no paper (d = d1) (step S2). The read paper thickness detection value V1 is stored in the set value data buffer 44 of the RAM 42.

Next, the composite processing apparatus 1 enters a state of waiting for insertion of the gauge sheet GS (step S3). Then, in this state of waiting for insertion, the gauge sheet GS having the reference thickness t ₀ is inserted into the first paper transport path P1, and the gauge sheet GS. When the pressing lever 30 is displaced by the thickness t ₀ , the composite processing apparatus 1 causes the paper thickness sensor 40 to read the paper thickness detection value V2 in the state where the gauge sheet GS is present (d = d2) (step S4). ). The read paper thickness detection value V2 is stored in the set value data buffer 44 of the RAM 42.

Next, the threshold value calculation unit 63 reads the paper thickness detection values V1 and V2 from the set value data buffer 44, and obtains the characteristic straight line E, that is, the slope α and the intercept β of the straight line E (step S5). Then, using the obtained characteristic straight line E and the values of the thickest paper thickness tmax and the thinnest paper thickness tmin stored in the flash ROM 48, the paper thickness value V3 and the threshold value serving as the lower limit of the threshold value Th are used. A paper thickness value V4 that is the upper limit of Th is calculated (step S6). Then, the threshold value calculation unit 63 adopts a value between the paper thickness value V3 and the paper thickness value V4 as the threshold value Th, and stores the adopted threshold value Th in the flash ROM 48 (step S7). When the threshold value Th is determined, the composite processing apparatus 1 performs end processing and ends the threshold setting mode.
The above is the flow of the threshold setting process.

  After setting the threshold value Th in this way, the check CK is inserted in the normal mode. Then, when one check CK is inserted, the output of the paper thickness sensor 40 does not exceed the threshold value Th, so the double feed determination unit 63 determines that one sheet is inserted, and double feed In the case of (insertion of two or more sheets), the output of the paper thickness sensor 40 exceeds the threshold value Th, so that the double feed determination unit 63 can determine that it is double feed.

  As described above, the composite processing apparatus 1 according to the present embodiment includes the paper thickness sensor 40 (paper thickness detection unit) that detects the thickness of the paper conveyed through the first paper conveyance path P1, and the output of the paper thickness sensor. Thickness comparison unit 61 that compares the threshold Th with a threshold value Th, a multi-feed determination unit 62 that performs multi-feed determination based on the comparison result of the paper thickness comparison unit 61, and a threshold calculation unit that calculates the threshold Th 63. The threshold value calculation unit 63 obtains a characteristic straight line (characteristic function) of the paper thickness sensor 40 based on the output of the paper thickness sensor 40 when a gauge sheet GS (reference paper) having a reference thickness is inserted. The threshold value Th is calculated by calculating the upper and lower limits of the threshold value Th using this characteristic line.

  Specifically, the threshold value calculation unit 63 calculates a characteristic straight line based on the output of the paper thickness sensor 40 in the absence of paper and the output of the paper thickness sensor 40 when the gauge sheet GS is inserted. Calculate. Further, the threshold value calculation unit 63 refers to the maximum thickness and the minimum thickness of the conveyed sheet, and more specifically, the threshold value calculating unit 63 is conveyed with the thickness of one of the thickest sheets among the conveyed sheets. The upper and lower limits of the threshold are calculated based on the thickness of the two thinnest papers.

  Therefore, according to the composite processing apparatus 1 including the double feed detection device 50 of the present embodiment, even when a plurality of checks CK having a large thickness variation between the checks CK are continuously conveyed, Since the threshold value Th is set after obtaining the upper limit of the threshold value Th and the lower limit of the threshold value Th, the threshold value Th can always be set in an appropriate region.

  Specifically, according to the composite processing apparatus 1 including the double feed detection device 50 of the present embodiment, more specifically, referring to the maximum thickness and the minimum thickness of the conveyed sheet, more specifically, the conveyed sheet. The upper and lower limits of the threshold are calculated based on the thickness of one of the thickest paper and the thickness of two of the thinnest paper among the conveyed paper. The threshold value Th can be appropriately set between the range of variation for one sheet and the range of variation for two sheets. Therefore, it is possible to provide an effective double feed detection device 50 and composite processing device 1 that do not cause erroneous detection depending on variations in sheet thickness.

  Further, in the composite processing apparatus 1 including the double feed detection device 50 of the present embodiment, the characteristic line E of the paper thickness sensor 40 is calculated based on the output of the paper thickness sensor 40 when the gauge sheet GS is inserted, The threshold value Th is determined based on the characteristic line E. Therefore, according to the present embodiment, the sensor sensitivity of each paper thickness sensor 40 provided in a plurality of double feed detection devices is expressed as a characteristic line, and the threshold value Th is obtained based on this characteristic function. Thus, it is possible to set a threshold value in consideration of variations in the above. Therefore, if the sheets have the same thickness, it is possible to make a uniform judgment in all the multifeed detection devices, and the multifeed detection device 50 and the composite processing device 1 that are easy to handle without fear of erroneous detection between lots. Can be provided.

  In the above embodiment, the gauge sheet GS is used as the reference sheet. However, the present invention is not limited to this, and the reference sheet having extremely high accuracy is supplied from the sheet feeding unit 3 to the first sheet conveyance path P1. The sheet thickness detection value when there is a sheet may be obtained.

  In the present embodiment, the threshold value is set by shifting to the setting mode. However, only the service person who performs maintenance of the composite processing apparatus 1 can perform the shift to the setting mode. It is preferable to configure as described above. Each user may set the threshold value Th using the gauge sheet GS. However, for example, by configuring so that only a service person can enter the setting mode, the user's hands are not bothered. , It is possible to make a professional threshold setting for the service person.

  The pressing lever 30 has been described as being pressed against the surface 13a of the MICR 13. However, the pressing lever 30 is not limited to this, and may be pressed against a non-movable fixed object that does not cause displacement or deformation. For example, the pressing lever 30 may be pressed against the inner wall that divides the paper conveyance path M or the image reading sensors 11 and 12 for image reading.

  The paper thickness sensor 40 has been described as an optical sensor. However, the present invention is not limited to this, and various displacement sensors that can detect the displacement of the pressing lever 30 (eg, magnetism, potential detection sensor, etc.) are used. May be.

  The indirect measurement type double feed detection device 50 that measures the displacement of the pressing lever 30 has been described. However, the present invention is not limited to this, and an optical paper detector is used to directly measure the thickness of the paper. Even if the measurement is performed, the same effect can be obtained.

(Double feed detection control and threshold setting: 2)
Next, another embodiment of control related to double feed detection of the composite processing apparatus 1 including the double feed detection device 50 of the present embodiment will be described.

  FIG. 12 is a flowchart showing a control flow of the threshold value setting process of the present embodiment.

  In the previous embodiment, the characteristic line E is first obtained, and then the threshold value is based on the thickness of one of the thickest paper among the papers to be transported and the thickness of the two thinnest papers of the paper to be transported. It has been described that the upper and lower limits of Th are calculated and the threshold value Th is appropriately set between the range of variation for one sheet and the range of variation for two sheets. However, there is variation in the thickness of the sheet. If less, the following threshold setting method may be used.

Specifically, referring to FIG. 12, first, the setting mode is started by operating the first switch (step S11), and the paper thickness detection value A of the paper thickness sensor 40 in the state of no paper is read (step S11). S12). Next, the composite processing apparatus 1 enters a paper insertion waiting state (step S13), and in this insertion waiting state, a gauge sheet GS (reference paper) having a reference thickness is inserted into the first paper transport path P1 (step S14). By operating the second switch, the paper thickness detection value B with the gauge sheet GS is read (step S15). Then, using the read paper thickness detection values A and B, a threshold Th for double feed determination is calculated by the following equation (11) (step 16). Here, the reference thickness that is the thickness of the gauge sheet GS is t ₀ , and the thickness that is the determination reference for the multifeed determination is t ₁ .

Th = [(B−A) / reference thickness t ₀ ] × judgment reference thickness t ₁ + A (11)

  Next, it is confirmed whether or not the threshold value Th is within the appropriate range (B <Th <C) (step S17). If it is not within the appropriate range (in the case of NO), “setting NG” and A, The values of B and Th are printed on roll paper or the like (step S18), and the process returns to step S13 waiting for paper insertion. If it is within the appropriate range (in the case of YES), “setting OK” and the values of A, B, and Th are printed on roll paper or the like (step S19), and the process proceeds to step S20. In this step S20, the gauge sheet is removed, the setting mode is canceled by the third switch operation, and the process ends. The value C is a paper thickness detection value of the paper thickness sensor 40 corresponding to the thickness of the two thinnest sheets.

FIG. 13A is a diagram showing the relationship between the passage of time according to the flow of processing and the output of the paper thickness sensor 40, and FIG. 13B is the thickness of the inserted paper and the output of the paper thickness sensor 40. It is a figure which shows the relationship. As shown in FIGS. 13 (a) and 13 (b), when there is no sheet (sheet), the sheet thickness detection value is A, and when a reference sheet (gauge sheet) having a thickness t ₀ is inserted, the sheet thickness is detected. The paper thickness detection value for the thickness t ₂ corresponding to the two thinnest papers is C, and the judgment reference thickness t1 is set between t0 and t2, and the sensor output at that time The value, that is, the threshold value Th is derived from, for example, the above equation (11).

In this way, a reference sheet having a reference thickness t ₀ is previously inserted into the sheet conveyance path, and a threshold value for determining multi-feed based on the sheet thickness detection value B of the sheet thickness sensor 40 corresponding to the reference thickness t _0. Since Th is set, it is possible to set an accurate threshold Th based on a reference sheet whose thickness is known in advance, regardless of the sheet that is actually inserted later. Therefore, it is possible to improve the accuracy of double feed detection performed based on the threshold Th.

  In particular, the calculation of the threshold Th is performed based on the paper thickness detection value A of the paper thickness sensor 40 when there is no paper and the output B of the paper thickness sensor 40 with the reference paper inserted. Even if the zero setting of the thickness sensor 40 is deviated, the threshold value Th can be set accurately. In addition, since the threshold value can be set only when the setting mode is selected, the setting mode can be clearly distinguished from the normal processing mode (the mode in which the setting mode is canceled). Only a service person can perform the operation, and unnecessary false detection can be avoided.

It is a perspective view which shows the compound processing apparatus of embodiment which concerns on this invention. FIG. 4 is a schematic diagram illustrating a sheet conveyance path in a composite processing apparatus. It is a schematic diagram which shows the internal structure of a composite processing apparatus. It is a perspective view of the compound processing apparatus which removed the housing | casing. It is a perspective view of the compound processing apparatus which removed the housing | casing. It is a schematic diagram which shows the double feed detection apparatus of this embodiment. (A) is a figure which shows the state (normal state) in which one check is conveyed in an intermediate conveyance path, (b) is the state in which two checks overlap and are conveyed in an intermediate conveyance path It is a figure which shows (double feed state). It is a control block diagram which shows one Embodiment of the double feed control which concerns on this invention. It is a figure which shows a gauge sheet. It is a figure which shows a characteristic straight line. It is a flowchart which shows a threshold value setting. It is a flowchart which shows another control flow of a threshold value setting process. (A) is a figure which shows the relationship between progress of time according to the flow of processing, and the output of a paper thickness sensor, (b) is a figure which shows the relationship between the thickness of the inserted paper, and the output of a paper thickness sensor. .

Explanation of symbols

1. ・ Composite processing device 2a ・ ・ Outside guide 2b ・ ・ Inside guide 3 ・ ・ Paper feed unit 4 ・ ・ Discharge port 11, 12 ・ ・ Image reading sensor 13 ・ ・ MICR 30 ・ ・ Pressing lever 40 ・ ・ Paper thickness sensor 42 .. RAM 48 .. Flash ROM 50 .. Double feed detection device 60 .. Control unit 61 .. Paper thickness comparison unit 62 .. Double feed judgment unit 63 .. Threshold calculation unit 70 .. Sampling pulse generator 85 ... Motor driver 90..Paper transport section

Claims (16)

A paper thickness detection unit for detecting the thickness of the paper conveyed through the paper conveyance path;
A paper thickness comparison unit that compares the output of the paper thickness detection unit with a threshold value;
A double feed determination unit that performs double feed determination based on a comparison result of the paper thickness comparison unit;
A threshold value calculation unit for calculating the threshold value,
The threshold value calculating unit calculates a threshold value of the paper thickness detecting unit based on an output of the paper thickness detecting unit when a reference sheet having a reference thickness is inserted. apparatus.   The threshold value calculation unit calculates the threshold value based on the output of the paper thickness detection unit when there is no paper and the output of the paper thickness detection unit when the reference paper is inserted. The double feed detection device according to claim 1.   The threshold value calculation unit obtains a characteristic function of the paper thickness detection unit based on an output of the paper thickness detection unit when a reference sheet having a reference thickness is inserted, and uses the characteristic function to determine the characteristic function. 2. The multifeed detection apparatus according to claim 1, wherein the threshold value is calculated by calculating an upper limit and a lower limit of a threshold value.   The threshold value calculation unit calculates the characteristic function based on the output of the paper thickness detection unit when there is no paper and the output of the paper thickness detection unit when the reference paper is inserted. The double feed detection device according to claim 3.   5. The multifeed detection according to claim 3, wherein the threshold value calculation unit calculates an upper limit and a lower limit of the threshold value with reference to a maximum thickness and a minimum thickness of a sheet to be conveyed. apparatus.   The threshold is calculated based on the thickness of one of the thickest papers to be transported and the thickness of two of the thinnest papers to be transported. The multifeed detection device according to claim 3, wherein the multifeed detection device is a multifeed detection device.   The multi-feed detection device according to claim 3, wherein the threshold value is an intermediate value between an upper limit of the threshold value and a lower limit of the threshold value.   A printer comprising the double feed detection device according to claim 1.   A composite processing apparatus comprising the double feed detection device according to claim 1. A reference thickness detecting step for obtaining an output of the paper thickness detecting unit corresponding to a reference thickness by inserting a reference sheet having a reference thickness into a paper transport path provided with a paper thickness detecting unit;
A threshold value calculating step for calculating a threshold value for multifeed determination based on the output obtained in the reference thickness detecting step,
The threshold value setting method, wherein the threshold value calculating step obtains a threshold value based on an output of the paper thickness detection unit.   The threshold value calculation unit calculates the threshold value based on the output of the paper thickness detection unit when there is no paper and the output of the paper thickness detection unit when the reference paper is inserted. The threshold value setting method according to claim 10.   The threshold value calculating step calculates a characteristic function of the paper thickness detection unit based on an output of the paper thickness detection unit, calculates an upper limit and a lower limit of the threshold value using the characteristic function, and The threshold value setting method according to claim 10, wherein a threshold value is calculated.   The threshold value calculating step calculates the characteristic function based on an output of the paper thickness detection unit when there is no paper and an output of the paper thickness detection unit when the reference paper is inserted. The threshold value setting method according to claim 12.   14. The threshold value according to claim 12, wherein the threshold value calculating step calculates an upper limit and a lower limit value of the threshold value with reference to the maximum thickness and the minimum thickness of the conveyed paper. Setting method.   The threshold is calculated based on the thickness of one of the thickest papers to be transported and the thickness of two of the thinnest papers to be transported. The threshold value setting method according to any one of claims 12 to 14, wherein: The threshold value setting method according to any one of claims 12 to 15, wherein the threshold value is an intermediate value between an upper limit value of the threshold value and a lower limit value of the threshold value.

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