JP7343389B2 - Foreign object detection device - Google Patents

Description

The present disclosure relates to a foreign object detection device.

As an example of the above foreign object detection device, a configuration is known in which a magnetic sensor detects a metal foreign object such as a clip. For example, in the passbook printing device of Patent Document 1, in order to avoid problems caused by conveying paper containing metal foreign matter, a magnetic sensor is provided upstream in the conveyance direction of the print head that prints on the passbook. When a foreign object is detected, the passbook is ejected before printing on the passbook.

Japanese Patent Application Publication No. 2000-1241

By the way, since the magnetic force of a metal foreign object such as a clip is small, there is a possibility that the magnetic sensor cannot accurately detect the metal foreign object.
An object of the present disclosure is to provide a foreign object detection device that can accurately detect metal foreign objects.

A foreign object detection device that solves the above problem includes one or more magnets that magnetize metal foreign objects contained in an object being transported, and a magnet that is disposed downstream in the transport direction with respect to the magnets, and one or more MI sensors that detect magnetism.

According to this configuration, the magnet applies magnetism to the foreign metal object included in the object, so that when the object includes a foreign metal object, the magnetic force of the foreign object increases. Therefore, magnetized metal foreign matter can be detected with high accuracy by the MI sensor.

According to the above foreign object detection device, metal foreign objects can be detected with high accuracy.

FIG. 1 is a schematic configuration diagram of a printing device including a foreign object detection device according to an embodiment. FIG. 2 is a plan view of a foreign object detection device. FIG. 3 is a diagram for explaining the detection operation of the foreign matter detection device, and is a plan view of the foreign matter detection device in a state where a sheet of paper passes through a magnet. FIG. 3 is a diagram for explaining the detection operation of the foreign matter detection device, and is a plan view of the foreign matter detection device in a state where a sheet of paper passes through the MI sensor. 5 is a flowchart illustrating an example of a processing procedure of an operation for detecting a metal foreign object by the foreign object detection device. FIG. 7 is a plan view of a plurality of MI sensors in a foreign object detection device according to a modified example. FIG. 6 is a schematic configuration diagram of a foreign object detection device according to a modification. FIG. 6 is a schematic configuration diagram of a foreign object detection device according to a modification. FIG. 7 is a plan view of a plurality of MI sensors in a foreign object detection device according to a modified example. FIG. 7 is a plan view of a plurality of MI sensors in a foreign object detection device according to a modified example. FIG. 7 is a plan view of a plurality of MI sensors in a foreign object detection device according to a modified example. FIG. 7 is a plan view of a plurality of MI sensors in a foreign object detection device according to a modified example. FIG. 7 is a plan view of a plurality of MI sensors in a foreign object detection device according to a modified example. FIG. 7 is a plan view of a plurality of MI sensors in a foreign object detection device according to a modified example. FIG. 7 is a plan view of a plurality of MI sensors in a foreign object detection device according to a modified example. FIG. 7 is a plan view of a plurality of magnets in a foreign object detection device according to a modified example. FIG. 7 is a plan view of a plurality of magnets in a foreign object detection device according to a modified example. FIG. 7 is a side view of a plurality of magnets in a foreign object detection device according to a modified example. FIG. 7 is a plan view of a plurality of magnets in a foreign object detection device according to a modified example. FIG. 7 is a schematic configuration diagram showing the relationship between a plurality of magnets and paper in a foreign matter detection device according to a modified example. FIG. 7 is a plan view of a plurality of magnets in a foreign object detection device according to a modified example. FIG. 7 is a plan view of a plurality of magnets in a foreign object detection device according to a modified example. FIG. 7 is a side view of a plurality of magnets in a foreign object detection device according to a modified example. FIG. 3 is a schematic configuration diagram of a printing device according to a modified example.

The foreign object detection device will be described below with reference to the drawings. The embodiments shown below illustrate configurations and methods for embodying technical ideas, and do not limit the material, shape, structure, arrangement, dimensions, etc. of each component to those below. . Various changes can be made to the embodiments below.

[Embodiment]
The foreign object detection device of this embodiment will be described with reference to FIGS. 1 to 4.
As shown in FIG. 1, the foreign object detection device 50 detects metal foreign objects contained in a sheet of paper P, which is an object formed in a sheet shape. It is provided. Examples of the metal foreign matter on the paper P include magnetizable metal parts such as a stapler (registered trademark) and a clip.

The printing device 1 includes a tray 10 on which one or more sheets of paper P is placed, a support stand 20 that supports the sheets of paper P that are conveyed one by one from the tray 10, and a support stand 20 that supports the sheets of paper P supported by the support stand 20. The printer includes a printing section 30 that performs printing, and a transport section 40 that transports sheets of paper P from the tray 10 onto the support stand 20 one by one. When a plurality of sheets of paper P are placed, it can be said that the sheets of paper P are stacked. The printing unit 30 prints on a sheet of paper P, for example, by ejecting ink onto a sheet of paper P that passes over the support base 20 . As shown in FIG. 1, the conveyance section 40 includes a plurality of conveyance rollers 41. These conveyance rollers 41 convey the uppermost sheet P of any one of the trays 10 toward the support stand 20, and discharge the sheet P that has passed over the support stand 20. Note that in this embodiment, as described above, the printing device 1 is an inkjet printer, but the invention is not limited to this. For example, a printer using other printing methods such as a thermal transfer printer or a laser printer may be used.

In the following description, for convenience, a predetermined conveyance roller 41 in the conveyance direction of the paper P (hereinafter simply referred to as "conveyance direction Y") among the plurality of conveyance rollers 41 will be referred to as a first conveyance roller 41A, and a predetermined conveyance roller 41 in the conveyance direction Y will be referred to as a first conveyance roller 41A. The conveyance roller 41 located downstream of the conveyance roller 41A is referred to as a second conveyance roller 41B. The downstream side in the transport direction Y refers to the side far from the tray 10 in the transport direction. The first conveyance roller 41A and the second conveyance roller 41B are spaced apart in the conveyance direction Y.

In the illustrated example, the first conveyance roller 41A is provided on the most upstream side in the conveyance direction Y among the plurality of conveyance rollers 41, that is, on the side closest to the tray 10 in the conveyance direction Y among the plurality of conveyance rollers 41. ing. The second conveyance roller 41B is provided at a position adjacent to the first conveyance roller 41A in the conveyance direction Y among the plurality of conveyance rollers 41. That is, the second conveyance roller 41B is provided second upstream among the plurality of conveyance rollers 41 in the conveyance direction Y.

The tray 10 is formed, for example, in a substantially box shape with an upper opening, and is configured to be openable and closable by being pulled out from the printing apparatus 1 in a horizontal direction. The tray 10 is made of, for example, a non-magnetic material, and in this embodiment is made of a resin material. The tray 10 is configured to be able to accommodate a plurality of sheets P in a stacked state. The tray 10 includes a bottom wall 11 that supports the paper P, and a side wall 12 rising from the outer periphery of the bottom wall 11. The side wall 12 is provided so as to surround the paper P, and restricts movement of the paper P that is not caused by the transport section 40. A plurality of sheets of paper P are stacked on the bottom wall 11. Further, one sheet of paper P may be placed on the bottom wall 11 in some cases.

The shape of the bottom wall 11 when viewed from the stacking direction of the sheets P is rectangular. The side walls 12 are provided on each of the four sides of the bottom wall 11. The side wall 12 is provided so as to be close to the paper P. Thereby, the side wall 12 restricts the movement of the paper P in a direction perpendicular to the stacking direction of the paper P.

As shown in FIG. 1, the foreign object detection device 50 is arranged between the first conveyance roller 41A and the second conveyance roller 41B in the conveyance direction Y.
As shown in FIG. 2, each foreign object detection device 50 includes a magnet 51 that generates a magnetic field, and a plurality of MI (Magneto Impedance) sensors 52 that output an output signal according to magnetism. In other words, the magnet 51 and the plurality of MI sensors 52 are arranged between the first conveyance roller 41A and the second conveyance roller 41B in the conveyance direction Y.

In this embodiment, the magnet 51 is disposed downstream of the first conveyance roller 41A in the conveyance direction Y and in the immediate vicinity of the first conveyance roller 41A. The magnet 51 is a permanent magnet, such as a neodymium magnet. Note that other magnets such as ferrite magnets may be used as the magnet 51. Further, the magnet 51 is not limited to a permanent magnet, and may be an electromagnet.

The magnet 51 is arranged in the width direction of the paper P (hereinafter simply referred to as "width direction ) from one end to the other end. In this embodiment, the magnet 51 extends in the width direction X, as shown in FIG. The length of the magnet 51 in the width direction X is longer than the length of the paper P in the width direction X. Thereby, the magnet 51 is configured to generate a magnetic field over the entire width direction X of the paper P.

The plurality of MI sensors 52 are arranged downstream of the magnet 51 in the transport direction Y. Each of the multiple MI sensors 52 is electrically connected to a control section (not shown) and outputs an output signal to the control section.

The control unit includes an arithmetic processing unit that executes a predetermined control program. The arithmetic processing device includes, for example, a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). The control unit may include one or more microcomputers. The control unit may include a plurality of arithmetic processing units arranged separately at a plurality of locations. The control unit further includes a storage unit. The storage unit stores various control programs and information used for various control processes. The storage unit includes, for example, nonvolatile memory and volatile memory. The control unit determines the presence or absence of metallic foreign matter on the paper P based on the output signals of the plurality of MI sensors 52. For example, if there is an MI sensor 52 whose output value (output signal magnitude) is equal to or greater than a threshold value, the control unit determines that the transported paper P contains a metal foreign object. In this way, the foreign object detection device 50 can also be said to include a control section.

In this embodiment, each of the plurality of MI sensors 52 is an MI sensor in which, for example, three MI sensors for sensing magnetism in three directions and control ICs for the three MI sensors are integrated into a package. This MI sensor is communicably connected to the control unit by I2C (Inter-Integrated Circuit). As shown in FIG. 2, each MI sensor 52 has a rectangular shape (square in this embodiment) when viewed from the thickness direction Z.

Each of the plurality of MI sensors 52 is mounted on a flat board (not shown). In this embodiment, the plurality of MI sensors 52 are surface-mounted packages, and are surface-mounted on a substrate. Each of the plurality of MI sensors 52 is electrically connected to the control section via a wiring pattern formed on the substrate. Note that the control unit may be mounted on a substrate, or may be mounted on a wiring board (not shown) provided outside the foreign object detection device 50.

As shown in FIG. 2, the plurality of MI sensors 52 are arranged in the width direction X while being aligned in the transport direction Y. In the illustrated example, the plurality of MI sensors 52 are arranged adjacent to each other in the width direction X. In other words, the plurality of MI sensors 52 are arranged in a line in the width direction X without gaps. Among the plurality of MI sensors 52, some of the MI sensors 52 at both ends in the width direction X are located outside the paper P in the width direction X. In this way, the plurality of MI sensors 52 are provided extending from one end of the paper P in the width direction X to the other end when viewed from the thickness direction Z. Thereby, the plurality of MI sensors 52 are arranged so as to face each other in the thickness direction Z over the entire width direction X of the sheet P.

The operation of detecting a metal foreign object contained in the paper P by the foreign object detection device 50 will be described. This detection operation is performed, for example, when the paper P is conveyed from the tray 10.
As shown in FIG. 3, when a sheet of paper P being conveyed passes the magnet 51, the paper P crosses the magnetic field of the magnet 51, and if the paper P contains a metal foreign material FM, the metal Foreign matter FM is magnetized. That is, the magnet 51 imparts magnetism to the foreign metal object FM.

As shown in FIG. 4, when one sheet of paper P passes through a plurality of MI sensors 52, the MI sensor 52 detects the magnetism of the metal foreign object FM. That is, the plurality of MI sensors 52 output signals corresponding to the magnetism of the metal foreign object FM to the control section of the foreign object detection device 50. The control unit determines the presence or absence of metallic foreign matter FM on one sheet of paper P based on the output signal of MI sensor 52. Specifically, as shown in FIG. 5, the control unit acquires the output value of each MI sensor 52 in step S1, and in step S2 selects the MI sensor 52 whose output value is equal to or higher than the threshold value among the plurality of MI sensors 52. Determine whether it exists. If there is an MI sensor 52 whose output value is greater than or equal to the threshold (step S2: YES), the control unit determines in step S3 that there is a metal foreign object FM, and ends the process. If there is no MI sensor 52 whose output value is equal to or greater than the threshold (step S2: NO), the control unit determines in step S4 that there is no metal foreign object FM, and ends the process.

The operation of this embodiment will be explained.
For example, when the magnetic force of the metal foreign object FM is small, even if the MI sensor 52 detects the metal foreign object FM, its output value is small. For this reason, even if the output signal from the MI sensor 52 is in response to the magnetism of the metal foreign object FM, there is a possibility that the control unit may determine that the metal foreign object FM does not exist due to a detection error of the MI sensor 52 or the like.

In view of this, in the present embodiment, the foreign object detection device 50 detects the presence of a metal foreign object FM such as a staple or a paper clip on the paper P by the magnetic field generated by the magnet 51. imparts magnetism to the metallic foreign object FM when passing through the magnetic field. As a result, the magnetic force of the foreign metal object FM increases. Then, the plurality of MI sensors 52 output signals corresponding to the metal foreign matter FM having a large magnetic force to the control unit. That is, the output value of the MI sensor 52 that has detected the metal foreign object FM increases. Therefore, it is possible to reduce the possibility that the metal foreign object FM cannot be detected due to a detection error of the MI sensor 52 or the like.

According to this embodiment, the following effects can be obtained.
(1) The foreign object detection device 50 includes a magnet 51 that magnetizes a metal foreign object FM included in one sheet of paper P being conveyed, and is disposed on the downstream side of the magnet 51 in the conveying direction. and a plurality of MI sensors 52 that detect the magnetic field. According to this configuration, since the metal foreign substance FM is magnetized, the output signal of the MI sensor 52 that detects the metal foreign substance FM increases, and the metal foreign substance FM included in the paper P can be detected with high precision.

Further, an MI sensor is used as a magnetic sensor that detects the magnetism of the metal foreign material FM. The MI sensor has higher magnetic sensitivity than other magnetic sensors such as Hall elements and MR (Magneto Resistance) sensors. Therefore, compared to a configuration in which a Hall element or an MR sensor is used as a magnetic sensor, the metal foreign matter FM included in the paper P can be detected with higher accuracy.

(2) The plurality of MI sensors 52 are arranged adjacent to each other in the width direction X. According to this configuration, there is no range in the width direction X in which the MI sensor 52 cannot detect the metal foreign object FM included in the paper P, so that detection failure of the metal foreign object FM occurs between adjacent MI sensors 52 in the width direction X. can be suppressed. Therefore, the metal foreign matter FM included in the paper P can be detected with high precision by the plurality of MI sensors 52.

(3) The plurality of MI sensors 52 are arranged in the width direction X so as to be aligned with each other in the transport direction Y. According to this configuration, the foreign object detection device 50 in the transport direction Y can be downsized.

(4) The plurality of MI sensors 52 are arranged across the entire sheet P in the width direction X so as to face the sheet P in the thickness direction Z. According to this configuration, the metal foreign matter FM included in the paper P can be detected with high precision over the entire width direction X of the paper P.

(5) The magnet 51 is provided from one end of the paper P in the width direction X to the other end when viewed from the thickness direction Z. According to this configuration, since a magnetic field is generated over the entire width direction X of the paper P, it becomes easier to impart magnetism to the metal foreign matter FM included in the paper P.

(6) The magnet 51 and the plurality of MI sensors 52 are arranged between the first conveyance roller 41A and the second conveyance roller 41B in the conveyance direction Y. According to this configuration, the metal foreign matter FM included in the paper P can be detected before the paper P is transported to the second transport roller 41B. Therefore, when conveyance of the paper P is stopped when the metal foreign object FM is detected, the paper P is sandwiched only between the first conveyance rollers 41A. This makes it easier to take out the paper P to the outside.

In particular, the magnet 51 and the plurality of MI sensors 52 are arranged between the first conveyance roller 41A and the second conveyance roller 41B, which are close to the tray 10 in the conveyance direction Y. According to this configuration, it is possible to detect the metal foreign object FM included in the paper P on the upstream side in the conveyance direction Y, so that when the metal foreign object FM included in the paper P is detected, it is easy to take out the paper P to the outside. Become.

[Example of change]
The embodiments described above are examples of forms that the foreign object detection device according to the present disclosure can take, and are not intended to limit the forms. A foreign object detection device according to the present disclosure may take a form different from the form illustrated in the above embodiment. An example thereof is a form in which a part of the structure of the above embodiment is replaced, changed, or omitted, or a form in which a new structure is added to the above embodiment. Furthermore, the following modifications can be combined with each other unless technically inconsistent. In each modification example below, the same parts as in the above embodiment are given the same reference numerals as in the above embodiment, and the explanation thereof will be omitted.

- In the above embodiment, the arrangement of the plurality of MI sensors 52 can be arbitrarily changed. For example, as shown in FIG. 6, MI sensors 52 adjacent in the width direction X may be arranged so as to be shifted from each other in the conveyance direction Y. In the illustrated example, MI sensors 52 adjacent in the width direction X are arranged so as to be shifted by one MI sensor 52 in the transport direction Y, but the arrangement is not limited thereto. The amount of deviation in the transport direction Y between the MI sensors 52 adjacent to each other in the width direction X may be smaller than one MI sensor 52 or larger than one MI sensor 52 . In the illustrated example, the plurality of MI sensors 52 are provided extending from one end of the paper P in the width direction X to the other end when viewed from the thickness direction Z. In the illustrated example, the plurality of MI sensors 52 are arranged across the entire paper P in the width direction X and facing the paper P in the thickness direction Z.

- In the above embodiment, the magnet 51 and the plurality of MI sensors 52 are arranged on the same side of the paper P in the thickness direction Z, but the present invention is not limited to this. As shown in FIG. 7, the magnet 51 may be arranged on one side of the paper P in the thickness direction Z, and the plurality of MI sensors 52 may be arranged on the other side of the paper P. Note that the positional relationship of the magnet 51 and the plurality of MI sensors 52 with respect to the paper P may be reversed to that in FIG. 7 .

- In the above embodiment, as shown in FIG. 8, a plurality of MI sensors 52 may be arranged on both sides of the paper P in the thickness direction Z. The plurality of MI sensors 52 include a first MI sensor group which is an MI sensor group arranged on one side of the paper P in the thickness direction Z, and a MI sensor group arranged on the other side of the paper P in the thickness direction Z. It can also be said that it has a certain second MI sensor group. In the illustrated example, the plurality of MI sensors 52A forming the first MI sensor group and the plurality of MI sensors 52B forming the second MI sensor group overlap when viewed from the thickness direction Z.

Note that the arrangement of the plurality of MI sensors 52A, 52B can be arbitrarily changed. The MI sensors 52A and 52B may be arranged so that the multiple MI sensors 52A and the multiple MI sensors 52B do not overlap when viewed from the thickness direction Z.

For example, as shown in FIG. 9, a plurality of MI sensors 52A are arranged apart from each other in the width direction X, a plurality of MI sensors 52B are arranged apart from each other in the width direction The MI sensors 52A and 52B are arranged alternately in the width direction X. In this case, when viewed from the thickness direction Z, the MI sensors 52A and 52B are aligned in the transport direction Y and spaced apart from each other in the width direction X. Here, when viewed from the thickness direction Z, the MI sensors 52A and 52B are not arranged in a line along the width direction X, but as shown in FIG. 52B may be arranged offset from each other in the transport direction Y. In FIGS. 9 and 10, both of the plurality of MI sensors 52A and 52B are provided extending from one end of the sheet P in the width direction X to the other end when viewed from the thickness direction Z. In FIGS. 9 and 10, both of the plurality of MI sensors 52A and 52B cover the entire sheet P in the width direction X and face the sheet P in the thickness direction Z.

- In the above embodiment, the plurality of MI sensors 52 are arranged adjacent to each other in the width direction X, but the present invention is not limited to this. For example, as shown in FIG. 11, the plurality of MI sensors 52 may be arranged apart from each other in the width direction X. In the illustrated example, the plurality of MI sensors 52 are aligned in the transport direction Y and spaced apart from each other in the width direction X. In the illustrated example, the plurality of MI sensors 52 are provided extending from one end of the paper P in the width direction X to the other end when viewed from the thickness direction Z. In the illustrated example, the plurality of MI sensors 52 are arranged across the entire paper P in the width direction X and facing the paper P in the thickness direction Z.

The manner in which the plurality of MI sensors 52 arranged so as to be spaced apart from each other in the width direction X can be arbitrarily changed. For example, among the plurality of MI sensors 52, the plurality of MI sensors 52 facing each other in the thickness direction Z at both ends in the width direction The MI sensor 52 facing Z is defined as a central MI sensor 52C. In this case, as shown in FIG. 12, the distance D1 between the end MI sensors 52E adjacent to each other in the width direction is smaller than the distance D2 between them. In this way, the multiple MI sensors 52 are located at positions facing both ends of the paper P in the width direction X and in the thickness direction Z, rather than at positions facing the center part of the paper P in the width direction X and the thickness direction Z. They are densely arranged.

By the way, the metal foreign matter FM included in the paper P is a staple or a clip, and is mainly attached to the outer periphery of the paper P. Therefore, the metal foreign matter FM is more likely to exist at the outer peripheral portion of the paper P than at the center of the paper P in the width direction X and the transport direction Y.

In view of this point, according to the configuration of the modified example shown in FIG. 12, it is possible to improve the detection accuracy of the metal foreign matter FM at both ends in the width direction X of the paper P where metal foreign matter is likely to exist. Therefore, the metal foreign matter FM contained in the paper P can be detected with high precision.

- In the above embodiment, as shown in FIG. 13, the foreign object detection device 50 includes two MI sensors 52 facing each of both ends of the paper P in the width direction X and in the thickness direction Z. Good too. In other words, the MI sensor 52 is not arranged at a position facing the center of the paper P in the width direction X and the thickness direction Z. According to this configuration, the cost of the foreign object detection device 50 can be reduced by reducing the number of MI sensors 52. In addition, since the two MI sensors 52 can detect the metal foreign matter FM at both ends of the paper P in the width direction It is possible to suppress an increase in the probability that the paper P will be transported.

- As in the modified example of FIG. 6, as the arrangement configuration of the plurality of MI sensors 52, the rows of the plurality of MI sensors 52 arranged in the width direction As a configuration in which two rows of MI sensors 52 are provided at one position, the pitch of the plurality of MI sensors 52 arranged in the width direction X while being aligned with each other in the conveyance direction Y can be arbitrarily changed. For example, the arrangement of the plurality of MI sensors 52 can be changed as shown in FIGS. 14 and 15. 14 and 15, a plurality of MI sensors 52 constituting an upstream row in the transport direction Y among a plurality of rows of MI sensors 52 arranged in the width direction X while being aligned with each other in the transport direction Y. are referred to as "a plurality of MI sensors 52U", and a plurality of MI sensors 52 that are aligned with each other in the transport direction Y and constitute a row on the downstream side in the transport direction Y are referred to as "a plurality of MI sensors 52L".

As shown in FIG. 14, the plurality of MI sensors 52U are arranged apart from each other in the width direction X. The plurality of MI sensors 52L are arranged apart from each other in the width direction X. The plurality of MI sensors 52U and the plurality of MI sensors 52L are arranged alternately from one side to the other side in the width direction X. The pitch of the multiple MI sensors 52U in the width direction X and the pitch of the multiple MI sensors 52L in the width direction X are each smaller than the dimension of the MI sensor 52 in the width direction X. Therefore, when viewed from the transport direction Y, a portion of the MI sensor 52U and a portion of the MI sensor 52L overlap. In the illustrated example, the pitches of the multiple MI sensors 52U in the width direction X and the pitches of the multiple MI sensors 52L in the width direction X are equal to each other.

As shown in FIG. 14, the plurality of MI sensors 52U and the plurality of MI sensors 52L are arranged adjacent to each other in the transport direction Y. Note that, as shown in FIG. 15, the plurality of MI sensors 52U and the plurality of MI sensors 52L may be arranged apart from each other in the transport direction Y. In FIGS. 14 and 15, both of the plurality of MI sensors 52U and 52L are provided extending from one end of the sheet P in the width direction X to the other end when viewed from the thickness direction Z. In FIGS. 14 and 15, both of the plurality of MI sensors 52U and 52L cover the entire sheet P in the width direction X and face the sheet P in the thickness direction Z.

Further, the pitch of the plurality of MI sensors 52U in the width direction X and the pitch of the plurality of MI sensors 52L in the width direction X may be different from each other. In this case, the number of multiple MI sensors 52U and the number of multiple MI sensors 52L may be different from each other. Furthermore, at least one of the plurality of MI sensors 52U and the plurality of MI sensors 52L may be arranged adjacent to each other in the width direction X. In other words, at least one of the multiple MI sensors 52U and the multiple MI sensors 52L may be arranged such that no gap is formed between adjacent MI sensors in the width direction X.

Further, three or more rows of the plurality of MI sensors 52 arranged in the width direction X may be provided at different positions in the transport direction Y. In this case, MI sensors that are adjacent in the transport direction Y may be arranged adjacent to each other in the transport direction Y, or may be arranged apart from each other in the transport direction Y.

- In the above embodiment, the magnets 51 may be arranged on both sides of the paper P in the thickness direction Z. According to this configuration, when the paper P includes a metal foreign substance FM, the magnetic force of the metal foreign substance FM becomes larger. Therefore, the metal foreign matter FM contained in the paper P can be detected with high precision.

- In the above embodiment, the foreign object detection device 50 includes one magnet 51, but is not limited to this, and may include a plurality of magnets 51. In this case, the plurality of magnets 51 are arranged in the width direction X. The arrangement of the plurality of magnets 51 can be arbitrarily changed. For example, as shown in FIG. 16, the plurality of magnets 51 are arranged in a row adjacent to each other in the width direction X. In the illustrated example, the plurality of magnets 51 are provided extending from one end of the sheet P in the width direction X to the other end when viewed from the thickness direction Z. In the illustrated example, the plurality of magnets 51 are arranged so as to cover the entire paper P in the width direction X and to face the paper P in the thickness direction Z.

For example, as shown in FIG. 17, the plurality of magnets 51 may be arranged apart from each other in the width direction X. In the illustrated example, the plurality of magnets 51 are aligned in the transport direction Y and spaced apart from each other in the width direction X. Note that the plurality of magnets 51 may be arranged so as to be offset from each other in the transport direction Y and spaced apart from each other in the width direction X. In the illustrated example, the plurality of magnets 51 are provided extending from one end of the sheet P in the width direction X to the other end when viewed from the thickness direction Z. In the illustrated example, the plurality of magnets 51 are arranged so as to cover the entire paper P in the width direction X and to face the paper P in the thickness direction Z.

The manner in which the plurality of magnets 51 arranged so as to be spaced apart from each other in the width direction X can be arbitrarily changed. For example, among the plurality of magnets 51, the plurality of magnets 51 facing each other in the thickness direction Z at both ends of the paper P in the width direction The magnet 51 facing Z is defined as a central magnet 51C. In this case, as shown in FIG. 18, the distance D3 between the end magnets 51E adjacent to each other in the width direction Smaller than D4. In this way, the plurality of magnets 51 are arranged more closely at the positions facing both ends of the paper P in the width direction X and the thickness direction Z than at the positions facing the center part of the paper P in the width direction X and the thickness direction Z. It is arranged as follows.

According to this configuration, it is possible to increase the magnetic flux density at both ends in the width direction X of the paper P where metal foreign matter FM is likely to exist. As a result, when magnetism is applied to the metal foreign substance FM included in the paper P, the magnetic force of the metal foreign substance FM increases. Therefore, the MI sensor 52 can detect the metal foreign matter FM with high accuracy.

- In the embodiment described above, the magnet 51 may be configured such that both ends of the paper P in the width direction X more easily magnetize the metal foreign matter FM than the center part of the paper P in the width direction X. For example, as shown in FIG. 19, auxiliary magnets 53 are arranged at positions facing both ends of the paper P in the width direction X and in the thickness direction Z. In the illustrated example, each auxiliary magnet 53 is located downstream of the magnet 51 in the transport direction Y. Further, the length of each auxiliary magnet 53 in the width direction X is shorter than the length of the magnet 51 in the width direction X.

According to this configuration, since the time to apply magnetism to both ends of the paper P in the width direction X where metal foreign matter FM is likely to exist is longer, when the metal foreign matter FM is included at both ends of the paper P, , the time for applying magnetism to the metal foreign material FM becomes longer. As a result, the magnetic force of the metal foreign material FM included in the paper P increases, so that the MI sensor 52 can detect the metal foreign material FM with high accuracy.

- In the above embodiment, a magnetic cover may be provided on the side of the magnet 51 opposite to the paper P in the thickness direction Z. The magnetic cover is made of a magnetic material so as to suppress leakage of magnetic flux to the side of the magnet 51 opposite to the paper P in the thickness direction Z. In one example, as shown in FIG. 20, the magnetic cover 60 includes a first cover part 61 that covers the magnet 51 from the side opposite to the paper P in the thickness direction Z, and a first cover part 61 that covers the magnet 51 from the width direction X and the conveyance direction Y. A second cover part 62 is provided. In the illustrated example, the magnetic cover 60 is a single component in which a first cover part 61 and a second cover part 62 are integrally formed. The second cover portion 62 covers the entire circumference of the magnet 51, for example.

According to this configuration, the magnetism generated by the magnet 51 tends to be directed toward the paper P, so that when a metal foreign material FM exists on the paper P, it becomes easier to impart magnetism to the metal foreign material FM. Therefore, the metal foreign matter FM on the paper P can be detected with high accuracy by the plurality of MI sensors 52. Note that the second cover portion 62 may be omitted from the magnetic cover 60.

- In the above embodiment and the above modification example, the shape of the magnet 51 viewed from the thickness direction Z can be arbitrarily changed. In one example, the shape of the magnet 51 viewed from the thickness direction Z may be square. Moreover, the shape of the magnet 51 viewed from the thickness direction Z may be a rectangular shape in which the width direction X is the long side direction and the conveyance direction Y is the short side direction.

- In the above embodiment, the arrangement of the plurality of magnets 51 can be arbitrarily changed. For example, as shown in FIG. 21, magnets 51 adjacent in the width direction X may be arranged so as to be shifted from each other in the conveyance direction Y. In the illustrated example, the magnets 51 adjacent in the width direction X are arranged so as to be shifted by the length of one magnet 51 in the transport direction Y, but the arrangement is not limited thereto. The amount of deviation in the conveying direction Y between the magnets 51 adjacent to each other in the width direction may also be large.

- As in the modification example shown in FIG. 21, as an arrangement configuration of the plurality of magnets 51, rows of the plurality of magnets 51 arranged in the width direction X while being aligned with each other in the transport direction Y are arranged at different positions in the transport direction Y. The pitch of the plurality of magnets 51 arranged in the width direction X while being aligned with each other in the transport direction Y can be arbitrarily changed. For example, the arrangement of the plurality of magnets 51 can be changed as shown in FIGS. 22 and 23. In FIGS. 22 and 23, the plurality of magnets 51 constituting the upstream row in the transport direction Y among the rows of the plurality of magnets 51 arranged in the width direction X while being aligned with each other in the transport direction Y is referred to as " A plurality of magnets 51U are referred to as "a plurality of magnets 51U", and a plurality of magnets 51 that are aligned with each other in the conveyance direction Y and constitute a row on the downstream side in the conveyance direction Y are referred to as "a plurality of magnets 51L".

As shown in FIG. 22, the plurality of magnets 51U are arranged apart from each other in the width direction X. The plurality of magnets 51L are arranged apart from each other in the width direction X. The plurality of magnets 51U and the plurality of magnets 51L are arranged alternately from one side to the other side in the width direction X. The pitch of the plurality of magnets 51U in the width direction X and the pitch of the plurality of magnets 51L in the width direction X are each smaller than the dimension of the magnet 51 in the width direction X. Therefore, when viewed from the transport direction Y, a portion of the magnet 51U and a portion of the magnet 51L overlap. In the illustrated example, the pitch of the plurality of magnets 51U in the width direction X and the pitch of the plurality of magnets 51L in the width direction X are equal to each other.

As shown in FIG. 22, the plurality of magnets 51U and the plurality of magnets 51L are arranged adjacent to each other in the transport direction Y. In addition, in FIG. 23, the plurality of magnets 51U and the plurality of magnets 51L may be arranged apart from each other in the transport direction Y. In FIGS. 22 and 23, both of the plurality of magnets 51U and 51L are provided extending from one end of the sheet P in the width direction X to the other end when viewed from the thickness direction Z. In FIGS. 22 and 23, both of the plurality of magnets 51U and 51L cover the entire sheet P in the width direction X and face the sheet P in the thickness direction Z.

Moreover, the pitch of the plurality of magnets 51U in the width direction X and the pitch of the plurality of magnets 51L in the width direction X may be different from each other. In this case, the number of multiple magnets 51U and the number of multiple magnets 51L may be different from each other. Further, at least one of the plurality of magnets 51U and the plurality of magnets 51L may be arranged adjacent to each other in the width direction X. In other words, at least one of the plurality of magnets 51U and the plurality of magnets 51L may be arranged so that no gap is formed between adjacent magnets in the width direction X.

Further, three or more rows of the plurality of magnets 51 arranged in the width direction X may be provided at different positions in the transport direction Y. In this case, magnets that are adjacent to each other in the transport direction Y may be arranged adjacent to each other in the transport direction Y, or may be arranged apart from each other in the transport direction Y.

- In the above embodiment, a plurality of magnets 51 shown in FIG. 2 may be arranged at different positions in the transport direction Y. In this case, the magnets 51 that are adjacent to each other in the transport direction Y may be arranged adjacent to each other in the transport direction Y, or may be arranged apart from each other in the transport direction Y.

- In the above embodiment and modified examples, the magnets 51 may be arranged in a part of the paper P in the width direction X so as to face each other in the thickness direction Z. In one example, the length of the magnet 51 in the width direction X is shorter than the length of the paper P in the width direction X.

- In the above modification, the plurality of magnets 51 may be arranged in a portion of the width direction X of the paper P so as to face each other in the thickness direction Z.
- In the above embodiment and modified examples, the plurality of MI sensors 52 may be arranged in a part of the width direction X of the paper P so as to face each other in the thickness direction Z.

- In the above embodiment, the positional relationship between the plurality of MI sensors 52 and the paper P viewed from the thickness direction Z can be arbitrarily changed. In one example, when viewed from the thickness direction Z, some of the multiple MI sensors 52 may be arranged at a position that does not overlap with the paper P.

- In the above modification example, the positional relationship between the plurality of magnets 51 and the paper P as viewed from the thickness direction Z can be arbitrarily changed. In one example, some of the magnets 51 among the plurality of magnets 51 may be arranged at positions that do not overlap the paper P when viewed from the thickness direction Z.

- In the above embodiment, the shape of the paper P viewed from the thickness direction Z can be arbitrarily changed. In one example, the shape of the paper P viewed from the thickness direction Z may be square, circular, oval, or the like. In this way, the shape of the object viewed from the thickness direction Z is arbitrary.

- In the above embodiment, the foreign object detection device 50 was provided in the middle of the conveyance path from the tray 10 to the support stand 20 and the printing unit 30, but the invention is not limited to this, and for example, as shown in FIG. 24, the image reading device 70 A foreign object detection device 50 may be provided. More specifically, the image reading device 70 includes a tray 71 on which paper P is placed, a transport unit 40S that transports the paper P placed on the tray 71, and a reading unit 72 that reads information on the transported paper P. It is equipped with.

The tray 71 is configured such that one or more sheets of paper P can be placed thereon. When a plurality of sheets of paper P are placed, it can be said that the sheets of paper P are stacked.
The transport unit 40S transports one or more sheets P placed on the tray 71 one by one. The conveyance section 40S includes a first conveyance roller 41SA and a second conveyance roller 41SB arranged downstream of the first conveyance roller 41SA in the conveyance direction YS of the conveyance section 40S. In the illustrated example, the first conveyance roller 41SA is arranged adjacent to the tray 10 on the downstream side of the tray 10 in the conveyance direction YS. The second conveyance roller 41SB is arranged upstream of the reading section 72 in the conveyance direction YS.

The reading unit 72 includes, for example, an optical reflection type image sensor. This image sensor includes a light emitting diode that irradiates light onto the transported paper P, and a light receiving diode that receives reflected light from the paper P.

The foreign object detection device 50 is arranged between the first conveyance roller 41SA and the second conveyance roller 41SB in the conveyance direction YS. The magnet 51 of the foreign object detection device 50 is arranged upstream of the MI sensor 52 in the transport direction YS. The configuration of this foreign object detection device 50 may be any of the configurations of the above-described embodiment and each of the above-described modifications. The foreign object detection device 50 determines the presence or absence of a metal foreign object FM contained in the sheet P when the sheet P placed on the tray 71 is transported by the transport section 40S.

- In the above embodiment, the foreign object detection device 50 is applied to the printing device 1, but the invention is not limited thereto. For example, the foreign object detection device 50 may be applied to a shredder. Further, the foreign object detection device 50 may detect a metal foreign object FM in an object other than the paper P. Objects other than paper P include sheet-like resin plates and seaweed. In short, the foreign object detection device 50 may be any device that detects metal foreign objects FM on a transportable object.
<Additional notes>
[Additional note 1]
one or more magnets that magnetize foreign metal objects contained in the object being transported;
one or more MI sensors that are arranged downstream in the conveying direction with respect to the magnet and detect magnetism of the foreign metal object.
Foreign object detection device.
[Additional note 2]
The object is formed in a sheet shape,
If the direction perpendicular to both the transport direction and the thickness direction of the object is the width direction of the object,
The plurality of MI sensors are arranged in the width direction and are provided at positions facing the object in the thickness direction.
The foreign object detection device according to Supplementary Note 1.
[Additional note 3]
The plurality of MI sensors are arranged adjacent to each other in the width direction.
The foreign object detection device according to Supplementary Note 2.
[Additional note 4]
The plurality of MI sensors are arranged spaced apart from each other in the width direction.
The foreign object detection device according to Supplementary Note 2.
[Additional note 5]
The plurality of MI sensors are provided extending from one end of the object to the other end in the width direction when viewed from the thickness direction.
The foreign object detection device according to appendix 3 or 4.
[Additional note 6]
Among the plurality of MI sensors, a plurality of MI sensors facing each other in the thickness direction at both ends of the object in the width direction are referred to as a plurality of end MI sensors, and the plurality of MI sensors in the central part of the object in the width direction are If multiple MI sensors facing each other in the thickness direction are defined as a central MI sensor,
The distance between the edge MI sensors adjacent in the width direction is smaller than the distance between the center MI sensor and the edge MI sensor closest to the center MI sensor in the width direction.
Foreign object detection device according to appendix 4.
[Additional note 7]
The MI sensors adjacent in the width direction are arranged offset from each other in the transport direction.
The foreign object detection device according to any one of Supplementary Notes 2 to 5.
[Additional note 8]
A plurality of rows of MI sensors arranged in the width direction are provided at mutually different positions in the transport direction,
When viewed from the transport direction, MI sensors that are adjacent to each other in the transport direction at least partially overlap.
The foreign object detection device according to any one of Supplementary Notes 2 to 5.
[Additional note 9]
MI sensors adjacent to each other in the transport direction are arranged adjacent to each other in the transport direction.
The foreign object detection device according to appendix 8.
[Additional note 10]
MI sensors adjacent to each other in the transport direction are spaced apart from each other in the transport direction.
The foreign object detection device according to appendix 8.
[Additional note 11]
The plurality of MI sensors include a first MI sensor group, which is a group of MI sensors arranged on one side of the object in the thickness direction, and a MI sensor group arranged on the other side of the object in the thickness direction. a second MI sensor group, which is a group of
The foreign object detection device according to Supplementary Note 2.
[Additional note 12]
Each of the first MI sensor group and the second MI sensor group is configured such that a plurality of MI sensors are arranged spaced apart from each other in the width direction,
When viewed from the thickness direction, the plurality of MI sensors of the first MI sensor group and the plurality of MI sensors of the second MI sensor group do not overlap.
The foreign object detection device according to appendix 11.
[Additional note 13]
When viewed from the thickness direction, the plurality of MI sensors forming the first MI sensor group and the plurality of MI sensors forming the second MI sensor group are adjacent to each other in at least one of the transport direction and the width direction. are arranged like
The foreign object detection device according to appendix 12.
[Additional note 14]
The object is formed in a sheet shape,
If the direction perpendicular to both the transport direction and the thickness direction of the object is the width direction of the object,
The magnet is provided extending from one end of the object to the other end in the width direction when viewed from the thickness direction.
The foreign object detection device according to any one of Supplementary Notes 1 to 13.
[Additional note 15]
The object is formed in a sheet shape,
If the direction perpendicular to both the transport direction and the thickness direction of the object is the width direction of the object,
The plurality of magnets are adjacent to each other in the width direction.
The foreign object detection device according to any one of Supplementary Notes 1 to 13.
[Additional note 16]
The object is formed in a sheet shape,
If the direction perpendicular to both the transport direction and the thickness direction of the object is the width direction of the object,
The plurality of magnets are spaced apart from each other in the width direction.
The foreign object detection device according to any one of Supplementary Notes 1 to 13.
[Additional note 17]
The plurality of magnets are provided from one end of the object to the other end in the width direction when viewed from the thickness direction.
The foreign object detection device according to appendix 15 or 16.
[Additional note 18]
Among the plurality of magnets, a plurality of magnets facing each other in the thickness direction at both ends of the object in the width direction are referred to as a plurality of end magnets, and a plurality of magnets facing each other in the thickness direction at both ends of the object in the width direction are referred to as a plurality of end magnets. Assuming that the multiple magnets facing the are the central magnet,
The distance between the end magnets that are adjacent to each other in the width direction is smaller than the distance between the center magnet and the end magnet that is closest to the center magnet in the width direction.
The foreign object detection device according to appendix 16.
[Additional note 19]
The object is formed in a sheet shape,
If the direction perpendicular to both the transport direction and the thickness direction of the object is the width direction of the object,
The plurality of magnets are arranged in the width direction so as to face at least both ends of the object in the width direction in the thickness direction.
The foreign object detection device according to any one of Supplementary Notes 1 to 13.
[Additional note 20]
The plurality of magnets are arranged at different positions in the transport direction.
The foreign object detection device according to any one of Supplementary Notes 1 to 13.
[Additional note 21]
The object is formed in a sheet shape,
If the direction perpendicular to both the transport direction and the thickness direction of the object is the width direction of the object,
The plurality of magnets have a plurality of rows of a plurality of magnets arranged in the width direction,
The plurality of rows of magnets are provided at different positions in the transport direction.
The foreign object detection device according to any one of Supplementary Notes 1 to 13.
[Additional note 22]
In the plurality of magnets, magnets that are adjacent to each other in the transport direction are arranged adjacent to each other in the transport direction.
The foreign object detection device according to appendix 21.
[Additional note 23]
In the plurality of magnets, magnets adjacent to each other in the transport direction are spaced apart from each other in the transport direction.
The foreign object detection device according to appendix 21.
[Additional note 24]
The foreign object detection device is provided in a printing device, and
The printing device includes a tray on which paper is placed as the object, and a transport unit that transports the paper placed on the tray,
The conveyance unit has a plurality of conveyance rollers arranged along the conveyance direction,
The magnet and the MI sensor are arranged between a first transport roller of the plurality of transport rollers and a second transport roller that is disposed downstream of the first transport roller in the transport direction.
The foreign object detection device according to any one of Supplementary Notes 1 to 23.

1... Printing device 10... Tray 40, 40S... Conveyance unit 41... Conveyance roller 41A, 41SA... First conveyance roller 41B, 41SB... Second conveyance roller 50... Foreign object detection device 51, 51L, 51U... Magnet 51C... Central magnet 51E ...End magnet 52, 52L, 52U...MI sensor 52A...MI sensor of first MI sensor group 52B...MI sensor of second MI sensor group 52C...Central MI sensor 52E...End MI sensor P...Paper (object)
FM...Metal foreign matter X...Width direction Y...Transportation direction Z...Thickness direction

Claims (22)

one or more magnets that magnetize foreign metal objects contained in the object being transported;
a plurality of MI sensors arranged on the downstream side of the conveyance direction with respect to the magnet and detecting magnetism of the foreign metal object ;
The object is formed in a sheet shape,
If the direction perpendicular to both the transport direction and the thickness direction of the object is the width direction of the object,
The plurality of MI sensors are arranged in the width direction and are provided at positions facing the object in the thickness direction,
The plurality of MI sensors are arranged spaced apart from each other in the width direction,
Among the plurality of MI sensors, a plurality of MI sensors facing each other in the thickness direction at both ends of the object in the width direction are referred to as a plurality of end MI sensors, and the plurality of MI sensors in the central part of the object in the width direction are If multiple MI sensors facing each other in the thickness direction are defined as a central MI sensor,
The distance between the edge MI sensors adjacent in the width direction is smaller than the distance between the center MI sensor and the edge MI sensor closest to the center MI sensor in the width direction.
Foreign object detection device. The foreign object detection device according to claim 1 , wherein the plurality of MI sensors are provided from one end of the object to the other end in the width direction when viewed from the thickness direction. The foreign object detection device according to claim 1 or 2 , wherein the MI sensors adjacent in the width direction are arranged offset from each other in the transport direction. A plurality of rows of MI sensors arranged in the width direction are provided at mutually different positions in the transport direction,
The foreign object detection device according to claim 1 or 2 , wherein MI sensors adjacent to each other in the transport direction at least partially overlap when viewed from the transport direction. The foreign object detection device according to claim 4 , wherein MI sensors adjacent in the transport direction are arranged adjacent to each other in the transport direction. The foreign object detection device according to claim 4 , wherein MI sensors adjacent to each other in the transport direction are spaced apart from each other in the transport direction. The plurality of MI sensors include a first MI sensor group, which is a group of MI sensors arranged on one side of the object in the thickness direction, and a MI sensor group arranged on the other side of the object in the thickness direction. The foreign object detection device according to claim 1 , further comprising: a second MI sensor group. Each of the first MI sensor group and the second MI sensor group is configured such that a plurality of MI sensors are arranged spaced apart from each other in the width direction,
The foreign object detection device according to claim 7 , wherein the plurality of MI sensors of the first MI sensor group and the plurality of MI sensors of the second MI sensor group do not overlap when viewed from the thickness direction. When viewed from the thickness direction, the plurality of MI sensors forming the first MI sensor group and the plurality of MI sensors forming the second MI sensor group are adjacent to each other in at least one of the transport direction and the width direction. The foreign object detection device according to claim 8 , wherein the foreign object detection device is arranged as follows. The object is formed in a sheet shape ,
The foreign object detection device according to any one of claims 1 to 9 , wherein the magnet is provided from one end of the object to the other end in the width direction when viewed from the thickness direction. The object is formed in a sheet shape ,
The foreign object detection device according to any one of claims 1 to 9 , wherein the plurality of magnets are adjacent to each other in the width direction. The object is formed in a sheet shape ,
The foreign object detection device according to any one of claims 1 to 9 , wherein the plurality of magnets are spaced apart from each other in the width direction. The foreign object detection device according to claim 11 or 12 , wherein the plurality of magnets are provided from one end of the object to the other end in the width direction when viewed from the thickness direction. Among the plurality of magnets, a plurality of magnets facing each other in the thickness direction at both ends of the object in the width direction are referred to as a plurality of end magnets, and a plurality of magnets facing each other in the thickness direction at both ends of the object in the width direction are referred to as a plurality of end magnets. Assuming that the multiple magnets facing the are the central magnet,
The foreign object detection device according to claim 12 , wherein the distance between the end magnets adjacent in the width direction is smaller than the distance between the center magnet and the end magnet closest to the center magnet in the width direction. . The object is formed in a sheet shape ,
The plurality of magnets are arranged in the width direction so as to face at least both ends of the object in the width direction in the thickness direction. Foreign object detection device. The foreign object detection device according to any one of claims 1 to 9 , wherein the plurality of magnets are arranged at different positions in the transport direction. The object is formed in a sheet shape ,
The plurality of magnets have a plurality of rows of a plurality of magnets arranged in the width direction,
The foreign object detection device according to any one of claims 1 to 9 , wherein the plurality of rows of magnets are provided at different positions in the transport direction. The foreign object detection device according to claim 17 , wherein the plurality of magnets that are adjacent to each other in the transport direction are arranged adjacent to each other in the transport direction. The foreign object detection device according to claim 17 , wherein the plurality of magnets that are adjacent to each other in the transport direction are spaced apart from each other in the transport direction. The foreign object detection device is provided in a printing device, and
The printing device includes a tray on which paper is placed as the object, and a transport unit that transports the paper placed on the tray,
The conveyance unit has a plurality of conveyance rollers arranged along the conveyance direction,
The magnet and the MI sensor are arranged between a first transport roller of the plurality of transport rollers and a second transport roller that is disposed downstream of the first transport roller in the transport direction. The foreign object detection device according to any one of claims 1 to 19 . one or more magnets that magnetize foreign metal objects contained in the object being transported;
a plurality of MI sensors arranged on the downstream side of the conveyance direction with respect to the magnet and detecting magnetism of the foreign metal object;
The object is formed in a sheet shape,
If the direction perpendicular to both the transport direction and the thickness direction of the object is the width direction of the object,
The plurality of MI sensors are arranged in the width direction and are provided at positions facing the object in the thickness direction,
The plurality of MI sensors include a first MI sensor group, which is a group of MI sensors arranged on one side of the object in the thickness direction, and a MI sensor group arranged on the other side of the object in the thickness direction. a second MI sensor group,
Each of the first MI sensor group and the second MI sensor group is configured such that a plurality of MI sensors are arranged spaced apart from each other in the width direction,
When viewed from the thickness direction, the plurality of MI sensors of the first MI sensor group and the plurality of MI sensors of the second MI sensor group do not overlap.
Foreign object detection device. a plurality of magnets that magnetize foreign metal objects contained in the object being transported;
one or more MI sensors arranged downstream in the transport direction with respect to the magnet and detecting magnetism of the foreign metal object;
The object is formed in a sheet shape,
If the direction perpendicular to both the transport direction and the thickness direction of the object is the width direction of the object,
The plurality of magnets are spaced apart from each other in the width direction,
Among the plurality of magnets, a plurality of magnets facing each other in the thickness direction at both ends of the object in the width direction are referred to as a plurality of end magnets, and a plurality of magnets facing each other in the thickness direction at both ends of the object in the width direction are referred to as a plurality of end magnets. Assuming that the multiple magnets facing the are the central magnet,
The distance between the end magnets that are adjacent to each other in the width direction is smaller than the distance between the center magnet and the end magnet that is closest to the center magnet in the width direction.
Foreign object detection device.