JP4828815B2 - Metal position detector - Google Patents

Description

  The present invention relates to a position detector for a metallic article held on an object to be inspected. More specifically, the present invention relates to a metallic property held on an object to be inspected based on a reading state of an RF tag in which position coordinate information is recorded. The present invention relates to a metal position detector that detects the position of an article.

In recent years, information recording media called IC cards are widely available on the market. The IC card is a generic name for cards having a card-like or sheet-like shape such as a credit card, a bank card, a point card, etc., and an IC (Integrated Circuit) incorporated in the card. Recently, RF tags that record information based on the same principle as IC cards have been attached to various products, contributing to efficiency in various fields such as product type and content discrimination, sorting and inventory management. . Since such IC cards and RF tags exchange data with reader / writers by radio waves, there is a particular problem that does not occur particularly with IC cards that are processed by a single card such as a commuter pass. is doing.
For example, when an RF tag is attached to an envelope and sorting or the like is performed, not only paper but also metal is included in the envelope. At this time, when the RF tag and the metal are close to each other or at least partly overlapped, if the reader / writer tries to read the recorded information of the RF tag, the RF tag is caused by the decrease of the magnetic flux due to the metal. A problem arises in that the energy applied is attenuated and the information of the RF tag cannot be read correctly.
In order to solve this problem, as shown in FIG. 11, a magnetic sheet 72 that forms magnetic paths of magnetic fluxes 70 and 73 is arranged on one side of the RF tag 200, so that a metal (in this case, a coin) ) 75 exists, the magnetic fluxes 70 and 73 cross the loop antenna (not shown) of the RF tag 200 using the magnetic sheet 72 as a magnetic path, so that communication with a reader / writer (not shown) can be performed. In the figure, the magnetic flux 74 is attenuated by the metal 75, but the magnetic sheet 72 becomes a magnetic flux path, and the influence of the metal can be ignored.
A non-contact type information transfer device including this magnetic sheet is disclosed in Patent Document 1. Further, a patent document 2 is filed by the same applicant regarding a special envelope having a configuration in which a metal and an RF tag are not superimposed in an envelope.
JP 2001-331772 A Japanese Patent Application No. 2004-280449

However, there is no particular problem if the envelope with the RF tag 200 having the magnetic sheet 72 shown in FIG. 11 is read by a reader / writer in units of one sheet, but it is very large for sorting a large number of overlapping envelopes. Takes a lot of time and is very inefficient.
In addition, a magnetic sheet must be attached to the RF tag, and there is a problem that the RF tag is expensive.
The invention of Patent Document 2 can reliably separate the positions of the metal and the RF tag, but has a problem that the envelope becomes special and a general-purpose envelope cannot be used.
In order to solve the above problems, if the position of the metal in the envelope can be detected in advance, the RF tag can be attached while avoiding the position. However, it is not easy to check whether there is an object (metal) that affects the transmission / reception of radio waves with the RF tag in a package that has already been packed or in a sealed envelope. Thus, a metal detector has conventionally existed as a device for detecting metal, but this could detect the presence or absence of metal, but could not detect the specific position of the metal.
In view of such problems, the present invention detects whether or not a metallic article is held on an object to be inspected by a simple method, and detects the position to indicate an appropriate position for attaching an RF tag. An object of the present invention is to provide a metal position detector capable of

In order to solve the above-described problems, the present invention provides a metal position detector for detecting the position of a metallic article held on an object to be inspected arranged in a detection unit, and is an abbreviation for a tag mounting surface. A plurality of RF tags arranged over the entire surface and recording individual two-dimensional position information, a command signal for reading the two-dimensional position information from each RF tag arranged opposite to the plurality of RF tags and returning An antenna for receiving a signal, a detector formed between the RF tag and the antenna, and a space in which the object to be inspected is disposed; and the two-dimensional position from each RF tag via the antenna A reader that reads information; and a control device that pre-stores the two-dimensional position information recorded in all the RF tags and controls the reader; and the control device drives the reader to control the antenna. Through Wherein when reading the individual two-dimensional position information from each RF tag, by comparing the two-dimensional position information of all the RF tags that are previously recorded in the control unit and the individual by the two-dimensional position information, stored The two-dimensional position of the metal article held by the inspection object is the two-dimensional position information of the RF tag that cannot read the two-dimensional position information because it is shielded by the metallic article among the two-dimensional position information It is characterized by being regarded as information.
The detection unit of the present invention includes, for example, a plurality of RF tags in which individual position information is recorded on one of two surfaces opposed to each other with a predetermined gap, and is connected to a reader on the other surface. Equipped antenna. Then, the inspection object is placed in the space of the detection unit, and the control device drives the reader to detect the presence or absence of an RF tag (that is, an RF tag shielded by a metallic article) that cannot read position information from the antenna, and the RF The position of the metallic article held by the inspection object is detected based on the position information that the tag should have. The antenna may be shared or separated for transmission and reception, and so on.
The second aspect of the present invention is a metal position detector for detecting the position of the metallic article held by the inspection object passing through the detection unit, and is a straight line that is orthogonal to the entry direction of the inspection object on the tag mounting surface. A plurality of RF tags that are arranged in a general manner and that record individual one-dimensional position information, a sensor that detects the passage or presence of the inspection object, a plurality of RF tags that are arranged opposite to the plurality of RF tags and that are one-dimensional from each RF tag An antenna that transmits a command signal for reading position information and receives a return signal; a detection unit that includes a space formed between the RF tag and the antenna and through which the inspection object passes; and the inspection object Conveying means for moving an object within the detection unit at a predetermined speed; a reader for reading the one-dimensional position information from each RF tag via the antenna; and the one-dimensional position information recorded on all the RF tags. Remember in advance Together, and a control unit for calculating a moving distance from the tip of the inspection object based on the speed of the conveying means passes through the sensor, the control device, the inspection object is the sensor When passing, drive the reader to read individual one-dimensional position information from each RF tag via the antenna, and compare the individual one-dimensional position information with the previously stored one-dimensional position information. Accordingly, when the one-dimensional position information of the mismatch and the previously stored one-dimensional position information exists, the tip of the inspection object is to calculate the travel distance from through said sensor, one-dimensional of the distance and mismatch It is determined that there is a metallic article held by the inspection object at a position where the position information intersects.
The present invention includes a sensor for detecting the passage or presence of an object to be inspected in order to save the number of RF tags used in the detection unit. That is, the position of the metallic article is detected on the basis of the position information on the heel of the RF tag that cannot read the timing and position information from the sensor. The sensor may be a transmission type or a reflection type. Thus, the position of the metallic article held on the object to be inspected can be detected based on the position information of the few RF tags and the detection timing of the sensor. Note that reading may be performed while relatively moving either the inspection object or the sensor.

According to a third aspect of the present invention, at least when the control device has successfully received the response signal from each RF tag a predetermined number of times as a result of reading the position information recorded on each RF tag by driving the reader, It is determined that there is no metallic article between the RF tag and the antenna.
The standard for the control device to determine that the metallic article is not held by the object to be inspected is when the response signal from each RF tag has been successfully received a predetermined number of times. There is another method of measuring the response signal level of the RF tag, but the circuit becomes complicated .

According to invention of Claim 1, the presence or absence of the RF tag which cannot arrange | position position information from an antenna by arrange | positioning a to-be-inspected object in the space between several RF tag and antenna which were opposingly arranged, and driving a reader, Since the position of the metallic article held on the inspection object is detected based on the position information that the RF tag should have, the position of the metallic article held on the inspection object can be confirmed two-dimensionally. it can.
According to a second aspect of the present invention, a sensor for detecting the passage or presence of the inspection object is provided, and the inspection object is passed or arranged in a space between the plurality of RF tags and the antennas arranged to face each other, and the reader is driven to remove the inspection object. Since the position of the metallic article held on the inspection object is detected based on the presence / absence of the RF tag whose position information cannot be read and the positional information that the RF tag should have, the position of the metallic article held on the inspection object Can be confirmed two-dimensionally.
According to the third aspect of the present invention, when the response signal from each RF tag is normally received a predetermined number of times, the control device determines that the metallic article is not held on the object to be inspected. It is possible to accurately determine the influence of the metal at the position .

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .
FIG. 1 is a block diagram showing a configuration of a general RF tag reader / writer. This RF tag reader / writer (hereinafter simply referred to as a reader / writer) 100 is controlled by a PC 50 that exchanges data with the reader / writer 100 and controls the entire system. The reader / writer 100 includes a transmission / reception device 1 that controls a data communication protocol with an external PC 50, a control device 2 that controls the operation of the entire reader / writer 100, firmware that records a procedure for operating the control device 2, and read data A memory device 3 for storing data, a modulator 4 for modulating data from the control device 2 on a carrier wave, an input device 5 for inputting an operation command, and a display device 6 for displaying information controlled by the control device 2 A power supply signal that is an AC signal from the control device 2 and a power amplifier 7 that amplifies the write command from the modulator 4, and a detection demodulation that converts the return signal received from the loop antenna 9 into binary data And a loop antenna 9 for exchanging power and data with an RF tag (not shown).
Next, before describing the operation of the reader / writer 100 according to this configuration, the configuration of the RF tag will be described first. FIG. 2 is a block diagram showing a configuration of a general RF tag. The RF tag 200 of the present embodiment receives a loop antenna 20 that transmits and receives data using a power carrier wave from the reader / writer 100, a transmission / reception circuit 21 that generates a write command read command, and a power carrier wave from the loop antenna 20. A power generation circuit 22 that rectifies and converts it into DC power, a memory device 23 that manages storage of control firmware and data, a modulator 24 that modulates a transmission command from the control circuit 26 with a carrier wave, The detector 25 is configured to convert the carrier wave data from the transmission / reception circuit 21 into binarized data, and the control circuit 26 controls the overall operation of the RF tag 200.

Next, each operation will be described with reference to FIGS. 1 and 2 together. When a power supply (not shown) is turned on, the reader / writer 100 starts an operation according to a program stored in the memory device 3 after the initial operation of the control device 2. First, initialization is performed. Next, in order to supply power to the RF tag 200, the control device 2 alternately transmits a carrier wave signal and a polling signal obtained by modulating the carrier wave signal from the power amplifier 7. The signal is radiated to the outside from the loop antenna 9 as an electromagnetic wave. Next, when the RF tag 200 comes close to the reader / writer 100, the loop antenna 20 rectifies the carrier wave by the power generation circuit 22 to convert it into DC power and supplies it to all the circuits in the RF tag. When power is supplied and the control circuit 26 is driven, control is started in accordance with a program stored in the memory device 23.
Next, the control circuit 26 first demodulates the command from the transmission / reception circuit 21 by the detector 25, converts it to a binary signal, and analyzes the command. As a result, when it is recognized that it is called, the response is modulated by the modulator 24 and transmitted from the loop antenna 20 via the transmission / reception circuit 21. The reader / writer 100 receives this response with the loop antenna 9, converts it into a binarized code with the detector demodulator 8, analyzes it with the control circuit 2, and recognizes that the RF tag 200 is a tag conforming to the standard. Thereby, data is exchanged between the reader / writer 100 and the RF tag 200 thereafter.
FIG. 3 is an external perspective view of the RF tag of the present invention. Hereinafter, the entire configuration is referred to as an RF tag. FIG. 3A is a top view, and FIG. 3B is a side view. As is clear from the top view of FIG. 3A, the RF tag 200 includes an inlet 31 in which the loop antenna 20 and the control IC 201 are integrated on a PVC sheet or the like, and a loop formed along the periphery of the inlet 31. The antenna 20 includes a control IC 201 that controls transmission of carrier power based on a predetermined modulation method and data exchange between the reader / writer 100 via the loop antenna 20.
In the following description of the embodiment, the reader / writer 100 of FIG. 1 is described as a reader 100 that only reads information recorded in the RF tag 200, but may have both functions as a writer. .

FIG. 4A is a configuration diagram of the metal position detector according to the first embodiment of the present invention. This metal position detector 300 records the position information of each RF tag and is arranged in a predetermined arrangement with a plurality of RF tags 200 facing each other via a space 42 and each RF tag. An antenna 9 that receives a return signal for reading position information from the tag 200, a detection unit 41 that includes a space 42 formed between the RF tag 200 and the antenna 9, and each RF tag 200 via the antenna 9. A reader 100 that reads position information from the PC, and a PC (control device) 50 that controls the reader 100 is provided. A restriction plate 47 that restricts the stop position of the envelope (inspection object) 40 is provided on one side of the detection unit 41 so that the position of the end of the envelope 40 can be easily determined. It is also possible to adopt a configuration in which no is provided. Here, the surface to which the RF tag 200 is attached is called a tag attachment surface 200a, and the surface to which the antenna 9 is attached is called an antenna surface 9a.
The detection unit 41 of the present embodiment includes, for example, a plurality of RF tags 200 in which individual position information is recorded on a tag attachment surface 200a facing the antenna surface 9a, and an antenna 9 connected to a reader on the antenna surface 9a. . The envelope 40 is disposed in the space 42 of the detection unit 41, and the PC 50 drives the reader 100 to detect the presence / absence of an RF tag that cannot read position information from the antenna 9 (that is, an RF tag shielded by the metal 45). The position of the metal 45 held in the envelope 40 is detected based on the position information of the bag that the RF tag cannot carry.

FIG. 4B is a functional block diagram of the metal position detector according to the first embodiment of the present invention. The same components will be described with the same reference numerals. The operation of the first embodiment will be described with reference to FIGS. 4 (a) and 4 (b). When the metal 45 is sealed in the envelope 40, it is impossible to distinguish the position of the metal from the appearance. Therefore, the envelope 40 is inserted into the space 42 from the upper opening (from the direction of the arrow A) or the side opening (from the direction of the arrow B) of the detection unit 41, and the end 40 a of the envelope 40 comes into contact with the regulation plate 47. Arrange so that. Thereby, the reference position of the detection part 41 and the edge part of the envelope 40 can be match | combined.
In this state, the PC 50 instructs a reading command to the reader 100. Then, a carrier wave is radiated from the antenna 9 from the reader 100 according to the procedure described in FIG. 1, and the RF tag 200 attached to the tag attachment surface 200a is activated to start communication. Two-dimensional position information, which will be described later, is recorded in each RF tag 200. If the metal is not sealed in the envelope 40, the PC 50 can accurately read all the position information through the reader 100. In other words, in this state, the PC 50 determines that the metal is not enclosed in the envelope 40. In the case of the present embodiment, since the metal 45 is sealed in the envelope 40, if there is an RF tag that is superimposed on or close to the metal 45, the response signal of the RF tag is lost or disturbed and the PC 50 is normal. Communication is impossible. However, the position information of all RF tags is stored in the PC 50 in advance, and even if the position information of the RF tag that cannot be communicated at that time cannot be recognized by the PC 50, the stored position information is stored. By comparing with the above, the position of the metal 45 can be accurately determined. Note that the PC 50 may always instruct the reader 100 to issue a read command.

  FIG. 5 is an external perspective view and a side view of the detection unit 41. The most characteristic point of the first embodiment is that a plurality of RF tags 200 in which two-dimensional position information (two-dimensional coordinates) of each RF tag is recorded are substantially the same as the tag mounting surface 200a as shown in FIG. It is the point which attached closely over. When a plurality of RF tags are arranged on a plane, they can be expressed by x-axis and y-axis coordinates, and different coordinates are recorded in each RF tag. That is, the two-dimensional coordinate information arranged in each RF tag is recorded. The antenna surface 9a is arranged so as to be able to communicate with all the RF tags having the antenna 9 attached to the tag attachment surface 200a. The tag mounting surface 200a and the antenna surface 9a are arranged to face each other, and a space 42 is provided therebetween. The length of this space should just be the distance which the electromagnetic wave radiated | emitted from the antenna 9 can start an RF tag normally. The antenna 9 may be configured outside the antenna surface 9a or embedded inside.

FIG. 7A is a configuration diagram of a metal position detector according to the second embodiment of the present invention. The same components will be described with the same reference numerals. The metal position detector 310 includes a plurality of RF tags 200 each recording individual position information, an antenna 9 that is disposed opposite to the plurality of RF tags 200 and receives radio waves for reading position information from each RF tag 200. , A space 42 formed between the RF tag 200 and the antenna 9, a detection unit 43 including sensors 48 and 49 for detecting the passage or presence of the envelope (inspection object) 40, and signals of the sensors 48 and 49 And a reader 100 that reads position information from each RF tag 200 via the antenna 9, and a PC (control device) 50 that controls the reader 100.
In the present embodiment, in order to save the number of RF tags 200 of the detection unit 43, sensors 48 and 49 for detecting passage or presence of the envelope 40 are provided. The sensors 48 and 49 may be transmissive or reflective. Thereby, the position of the metal 45 held by the envelope 40 can be detected based on the position information of the few RF tags and the timing of the sensor. Note that reading may be performed while relatively moving either one of the envelope 40 and the sensors 48 and 49.
FIG. 7B is a functional block diagram of a metal position detector according to the second embodiment of the present invention. The same components will be described with the same reference numerals. The operation of the second embodiment will be described with reference to FIGS. 7 (a) and 7 (b). In this embodiment, a case where a transmissive photosensor is used as a sensor will be described. When the metal 45 is sealed in the envelope 40, it is impossible to distinguish the position of the metal from the appearance. Therefore, the envelope 40 is passed through the space 42 from the opening (from the direction of arrow A) on the side surface of the detection unit 41 at a predetermined speed. In FIG. 7 (a), the configuration for passing the envelope 40 at a predetermined speed is not shown, but for example, a detection roller 43 is provided with a pair of conveyance rollers, and the envelope 40 is sandwiched between the roller pair and conveyed. Also good.

  The most characteristic point of this embodiment is that a plurality of RF tags 200 in which one-dimensional position information (one-dimensional coordinates) of each RF tag is recorded on the tag mounting surface 200a are orthogonal to the approach direction as shown in FIG. It is a point pasted so as to cross. That is, when a plurality of RF tags are linearly arranged, they can be expressed by either x-axis or y-axis coordinates, and the coordinates are different for each RF tag. In this embodiment, sensors 48 and 49 are provided at the entrance and exit of the detection unit 43 in order to reduce the number of RF tags. In the figure, 48a and 49a are light emitting portions, and 48b and 49b are light receiving portions. First, when the end portion of the envelope 40 blocks the transmitted light from the light emitting portion 48 a of the sensor 48, the signal of the light receiving portion 48 b is amplified and shaped by the photosensor amplifier 44 and input to the PC 50. When this signal is received, the PC 50 instructs the reading command to the reader 100. Then, a carrier wave is radiated from the antenna 9 from the reader 100 according to the procedure described in FIG. 1, and the RF tag 200 attached to the tag attachment surface 200a is activated to start communication. One-dimensional position information, which will be described later, is recorded in each RF tag 200. If no metal is sealed in the envelope 40, the PC 50 can accurately read all the position information via the reader 100. In other words, in this state, the PC 50 determines that no metal is sealed in the envelope 40. In the case of this embodiment, since the metal 45 is sealed in the envelope 40, if there is an RF tag superimposed or close to the metal 45, the response signal of the RF tag disappears or is disturbed and the PC 50 is normal. Communication is impossible. However, the position information of all RF tags is stored in the PC 50 in advance, and even if the position information of the RF tag that cannot be communicated at that time cannot be recognized by the PC 50, the stored position information is stored. It is possible to accurately determine the one-dimensional coordinate position of one of the metals 45. The other one-dimensional coordinate position can be calculated from the time from when the sensor 48 detects the end of the envelope 40 to when the one-dimensional coordinate position is detected by the RF tag. Based on the two one-dimensional coordinate positions, the two-dimensional coordinate position of the metal 45 in the envelope 40 can be detected (details will be described later).

  FIG. 8 is a diagram illustrating an example using the metal position detector 300 according to the first embodiment of the present invention. The same components will be described with the same reference numerals. FIG. 8A is a perspective view when the tag attachment surface 200a and the envelope 40 are disposed (however, the antenna is omitted), and FIG. 8B is an example in which the detection result is displayed on the display unit of the PC 50. FIG. In the present embodiment, 15 RF tags 200 are provided in the vertical and horizontal directions on the tag mounting surface 200a, and the envelopes 40 are filled with metal 45a and 45b. When detection is started in this state, the information on the RF tags A3 and B3 is shielded by the metal 45b and the response signal cannot be read normally, and the information on the RF tags D3 and E3 is shielded by the metal 45a and the response signal is normal. can not read. As a result, the display unit 46 is marked on the images A3, B3, D3, and E3 corresponding to the RF tag whose response signal cannot be read normally. The operator can confirm the position of the metal sealed in the envelope 40 from this screen, and by attaching an RF tag to other places, it is possible to avoid the influence of the magnetic flux attenuation failure due to the metal.

FIG. 9 is a diagram for explaining an example using the metal position detector 310 according to the second embodiment of the present invention. The same components will be described with the same reference numerals. FIG. 9A is a view showing a state in which the envelope 40 passes in the direction of arrow D with respect to the tag mounting surface 200a (however, the antenna is omitted), and FIG. 9B is a view of the sensor and the RF tag. It is a figure showing a detection state. In the present embodiment, it is assumed that three RF tags 200 (RF1 to RF3) are provided on the tag mounting surface 200a in the vertical direction, and a metal 45 is sealed in the envelope 40. First, when the tip of the envelope 40 is at the A position, the sensor S1 detects the envelope 40, all the RF tags 200 (RF1 to RF3) do not detect the metal 45, and the sensor S2 also does not detect the envelope 40 It is. Next, when the tip of the envelope 40 is at the B position, the sensor S1 detects the envelope 40, only the RF3 of the RF tag 200 detects the metal 45, and the sensor S2 has not yet detected the envelope 40. . Next, when the tip of the envelope 40 is in the C position, the sensor S1 detects the envelope 40, the metal 45 does not pass through the RF3 of all the RF tags 200 and does not detect the metal 45, and the sensor S2 detects the envelope 40. It is in a detecting state.
The series of operations described above is represented as a matrix in the table of FIG. 9B. The vertical axis represents the tip position of the envelope 40, and the horizontal axis represents the sensor S1, the RF tags (RF1 to RF3), and the sensor S2. . “◯” represents detection and “×” represents non-detection.

  FIG. 10 is a timing chart of the sensor and the RF tag shown on the horizontal axis in FIG. 9B when the envelope 40 passes the detection unit 43 as shown in FIG. The vertical axis represents sensors and RF tags, and the horizontal axis represents time. First, sensor S1 detects the tip of envelope 40 at time T1, and RF3 detects metal 45 at time T2. At that time, if the elapsed time “t1” from time T1 to T2 is measured by the PC 50 and the passing speed of the envelope 40 is V, the distance Dt from the tip of the envelope 40 to the metal 45 is calculated by Dt = V · t1. can do. The position of the metal 45 can be calculated from the value of Dt and the one-dimensional coordinates recorded in RF3.

It is a block diagram which shows the structure of the reader / writer for general RF tags. It is a block diagram which shows the structure of a general RF tag. (A) and (B) are external perspective views of a general RF tag. (A) is a block diagram of the metal position detector which concerns on the 1st Embodiment of this invention, (b) is a functional block diagram of the metal position detector which concerns on the 1st Embodiment of this invention. (A) is an external appearance perspective view of the detection part of this invention, (b) is a side view of the detection part of this invention. (A) is the figure which affixed several RF tag so that it might cross orthogonally to an approach direction, (b) is the figure which affixed several RF tag on the whole surface. (A) is a block diagram of the metal position detector which concerns on the 2nd Embodiment of this invention, (b) is a functional block diagram of the metal position detector which concerns on the 2nd Embodiment of this invention. (A) is a perspective view when a tag mounting surface and an envelope are arranged (however, the antenna is omitted), and (b) is a diagram showing an example in which a detection result is displayed on a display unit of a PC. (A) is a figure showing a mode that an envelope passes in the direction of arrow D to a tag attachment surface (however, an antenna is omitted), and (b) is a figure showing a detection state of a sensor and an RF tag. It is a timing chart of a sensor and RF tag. It is a figure explaining the operation | movement of the magnetic flux at the time of forming the magnetic sheet which forms the magnetic path of magnetic flux in the single side | surface of the conventional IC tag.

Explanation of symbols

  9 antenna, 41 detector, 42 space, 50 PC (control device), 100 reader, 200 RF tag, 300 metal position detector

Claims (3)

A metal position detector for detecting the position of a metallic article held on an object to be inspected arranged in a detection unit,
A plurality of RF tags that are arranged over substantially the entire surface of the tag and record individual two-dimensional position information, and a command for reading the two-dimensional position information from each RF tag that is arranged opposite to the plurality of RF tags. An antenna that transmits a signal and receives a return signal; a detection unit that includes a space formed between the RF tag and the antenna and in which the object to be inspected is disposed; and each of the RF tags via the antenna A reader that reads the two-dimensional position information from, and a control device that pre-stores the two-dimensional position information recorded in all RF tags and controls the reader,
When the controller drives the reader to read individual two-dimensional position information from each RF tag via the antenna, the individual two- dimensional position information and all of the information previously recorded in the controller are recorded. by comparing the two-dimensional position information of the RF tag and the two-dimensional position information of the RF tag that can not be read the two-dimensional position information by being shielded by the metal article of two-dimensional position information stored Is a metal position detector characterized in that it is the two-dimensional position information of the metal article held on the object to be inspected. A metal position detector that detects the position of a metallic article held by an object to be inspected that passes through a detection unit ,
A plurality of RF tags that are linearly arranged on the tag mounting surface so as to be orthogonal to the entry direction of the inspection object and that record individual one-dimensional position information, a sensor that detects the passage or presence of the inspection object, An antenna that is arranged opposite to the plurality of RF tags and that transmits a command signal for reading the one-dimensional position information from each RF tag and receives a return signal; and an antenna formed between the RF tag and the antenna; and A detector having a space through which the object to be inspected passes ;
Transport means for moving the object to be inspected at a predetermined speed in the detection unit;
A reader for reading the one-dimensional position information from each RF tag via the antenna;
A control device for preliminarily storing the one-dimensional position information recorded in all the RF tags and calculating a moving distance from the tip of the inspection object passing through the sensor based on the speed of the conveying means; With
When the inspection object passes the sensor, the control device drives the reader to read individual one-dimensional position information from each RF tag via the antenna, and by comparing the one-dimensional position information which the previously stored, when the one-dimensional position information of the mismatch and the previously stored one-dimensional position information exists, the distal end of the object to be inspected from through said sensor A metal position detector characterized by calculating a moving distance and determining that a metallic article held on the object to be inspected exists at a position where one-dimensional position information that does not match the distance intersects.   When the control device has successfully received a response signal from each RF tag a predetermined number of times as a result of reading the position information recorded on each RF tag by driving the reader, at least the RF tag and the antenna The metal position detector according to claim 1, wherein it is determined that there is no metallic article between the first and second metal objects.

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