JP2001043459A - Magnetic type article monitoring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic type article monitoring device by which a tag is surely detected in a gate. SOLUTION: In the device, a pair of energizing coils 1a and 1b constituted by respectively superimposing a pair of main coils 4 and 6 which are respectively provided with a part where current is made to flow in a same direction and with a part where current is made to flow in the different direction in a parallel and horizontal Y direction and a vertical Z direction concerning the movement direction of an article with the tag 3 and also auxiliary coils 5 and 7 are arranged at prescribed interval to permit the part where current is made to flow in the same direction to be opposed to the part where current is made to flow in the different direction. A part between the energizing coils 1a and 1b is made to be the gate for passing through the tag 3 and a detection coil is disposed in the gate, which detects that the magnetic flux densities of magnetic fields generated by the respective energizing coils 1a and 1b are changed by the passing-through of the tag 3. Electromagnetic waves are not cancelled each other in any one of X, Y and Z directions in the gate so that the tag 3 is surely detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects the movement of an article by identifying a tag attached to an article such as a product and having a magnetic member, and attaches a tag to the article in a store or the like to identify the tag. The present invention relates to a magnetic article monitoring device for detecting theft of a product or the like, and in particular, detects a signal caused by a change in the magnetic flux density of a magnetic member that changes its magnetic flux density when exposed to a magnetic field. The present invention relates to a magnetic article monitoring device that detects the presence or absence of a tag including the magnetic member by obtaining the tag with a magnetic member, by obtaining the signal with a predetermined value.

In the description of the present invention or the conventional example in this specification, the directions of electromagnetic waves generated by an exciting current flowing through a pair of exciting coils arranged to form a gate are defined as X direction and X direction, respectively. The description will be made by disassembling in the Y direction and the Z direction. The X direction is the horizontal direction connecting the two exciting coils, and the Y direction is the depth direction of the horizontal gate perpendicular to the direction connecting the exciting coils. And the Z direction indicates the vertical direction.

[0003]

2. Description of the Related Art Conventionally, a magnetic article monitoring apparatus is provided with an excitation coil to which a predetermined excitation signal is applied and a detection coil for detecting a magnetic field, facing each other, and forming a gate between them. When the article with the tag having the material moves, the change in the magnetic flux density generated in the tag by the magnetic field from the excitation coil is detected by the detection coil, and it is determined that the magnetic field is from the tag under predetermined conditions. In some cases, the movement of the tag is determined to be the movement of a product or the like, thereby preventing the product or the like from being stolen in a store or the like. The current of the exciting coil used in the magnetic article monitoring device is configured to flow only in the same direction or the opposite direction as shown in FIG. 7 or FIG.

FIGS. 7 to 9 show a first conventional example, and FIG. 7 is a schematic perspective view of a magnetic article monitoring apparatus in which a gate is formed by a pair of exciting coils having the same exciting current, and FIG.
Is a plan view showing the magnetic field direction when the gate of FIG. 7 is viewed from above, and FIG. 9 is a front view showing the magnetic field direction when the gate of FIG. 7 is viewed from the front. FIGS. 10 to 12 show a second conventional example, and FIG. 11 is a schematic perspective view in which a gate is formed by a pair of exciting coils whose exciting currents are in opposite directions.
FIG. 11 is a plan view showing the magnetic field direction when the gate of FIG. 10 is viewed from above, and FIG. 12 is a front view showing the magnetic field direction when the gate of FIG. 10 is viewed from the front. Here, in FIGS. 8, 9, 11 and 12, black arrows indicate the direction of current flow, white arrows indicate the direction of the magnetic field, and wide arrows indicate the direction of the electromagnetic waves.

[0005]

In the first conventional example, as shown in FIGS. 8 and 9, electromagnetic waves reinforce each other in the same direction in the X direction, but cancel out in the Y and Z directions. In particular, the value is zero at the center of the gate, and the change in the magnetic field due to the tag passing therethrough cannot be detected. In the second conventional example, as shown in FIGS. 11 and 12,
Although the electromagnetic waves reinforce each other in the same direction in the Y direction and the Z direction, they cancel each other out in the X direction, and especially, are zero at the center of the gate, and cannot detect a change in the magnetic field due to the tag passing therethrough. There was a problem.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to effectively detect electromagnetic waves in any of the X, Y, and Z directions so as to detect a tag passing at any place of the gate. It is an object of the present invention to provide a magnetic article monitoring device that performs the following.

[0007]

According to the present invention, in order to achieve the above object, a magnetic member which is exposed to a magnetic field and causes a change in magnetic flux density causes a change in the magnetic flux density. A magnetic signal monitoring device that detects the presence or absence of a tag provided with the magnetic member by obtaining a signal to be performed by a detection coil and comparing the signal with a predetermined value. A pair of exciting coils formed by superimposing two coils each having a portion in which a current flows in the same direction and a portion in which a current flows in a different direction, respectively, in a horizontal Y direction and a vertical Z direction parallel to the direction, A portion where a current flows in the same direction and a portion that flows in a different direction are arranged at predetermined intervals so as to face each other, and a gate through which a tag passes between both coils is formed. In which the magnetic flux density of the magnetic field generated by the magnetic coil is provided with a detection coil for detecting a change by passage of the tag.

According to a second aspect of the present invention, a signal resulting from a change in the magnetic flux density of a magnetic member which is subjected to a change in the magnetic flux density when exposed to a magnetic field is obtained by a detection coil. A magnetic article monitoring apparatus for detecting presence or absence of a tag provided with the magnetic member by comparing a signal with a predetermined value, wherein a Y direction parallel to a moving direction of the article with the tag and a Z direction parallel to a moving direction of the article with the tag are provided. In each of the directions, an excitation coil in which a main coil in which current flows in one direction, an auxiliary coil formed by connecting an outer path to a central merging path from both sides is superimposed, and a current direction of a main coil of the excitation coil opposite to the current direction. The excitation coil, which is formed by superimposing an auxiliary coil consisting of an outer path connected from both sides to a central merging flow path, on the main coil, in which current flows in the same direction, Are arranged at a predetermined interval so that the parts flowing through the coils are opposed to each other, and a gate through which the tag passes between both coils is formed. At this gate, the magnetic flux density of the magnetic field generated by each of the exciting coils changes due to the passage of the tag. This is provided with a detection coil for detecting that the operation has been performed.

[0009]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Here, FIGS. 1 to 4 of the accompanying drawings show an embodiment of the present invention,
FIG. 1 is an exploded perspective view of an excitation coil including a pair of main coils and an auxiliary coil, FIG. 2 is a development view of the excitation coil including a pair of main coils and an auxiliary coil as viewed from the inside of a gate, and FIG. FIG. 4 is a schematic view of a gate showing the direction of an electromagnetic wave when the magnitude of the current of the coil and the auxiliary coil is the same, viewed from above,
FIG. 5 is a schematic view of a gate showing the direction of an electromagnetic wave when the magnitudes of currents of the main coil and the auxiliary coil are different, as viewed from above,
6 is a developed view of a pair of excitation coils according to another embodiment viewed from the inside of a gate.

As shown in FIG. 1, a magnetic article monitoring apparatus is a tag 3 having a magnetic member whose magnetic flux density changes when exposed to a magnetic field at a gate 2 between a pair of exciting coils 1a and 1b. It is configured to detect the presence or absence of the tag 3 by obtaining a signal resulting from the change in the magnetic flux density by a detection unit (not shown) and comparing the signal with a predetermined value. That is, the detection unit has a known configuration, and the excitation coils 1a, 1b
Is provided on each panel (not shown) on which is disposed a detection coil (not shown) disposed together with each of the excitation coils 1a and 1b. With this detection coil, the gate 2 is connected to the excitation coil 1a and 1b by the respective excitation coils 1a and 1b. It detects that the magnetic flux density of the generated magnetic field has changed by passing through the tag 3. The tag 3 is formed by attaching a magnetic member (not shown) to a label body formed in a plate shape or a film shape using, for example, paper or vinyl resin.
It is bonded with an adhesive on an appropriate surface of an article such as a product.

The exciting coils 1a and 1b are opposed to, for example, entrances and exits of a store or the like, and are separated from each other by a distance enough to allow a person to pass through. A magnetic field is generated. On the other hand, a detecting unit (not shown) is provided with the exciting coils 1a and 1b.
A pulse signal generated by the tag 3 when the tag 3 passes through the gate 2 between the detection gates is amplified. A signal generated by a change in a magnetic field crossing the detection coil is amplified, and a signal level required for signal processing is amplified. And the like, and input to a control unit (not shown).

The excitation unit includes a digital / analog converter (not shown), a low-pass filter, and an excitation amplifier.

The digital / analog converter converts the digital sine wave output from the control unit to an analog sine wave.
The SIN wave is applied to the exciting coils 1a and 1b, and the control unit executes a well-known SIN wave generation program to output a digital SIN wave signal. It is configured to be performed. The low-pass filter is for removing unnecessary high-frequency components contained in the analog sine wave signal output from the digital-to-analog converter to obtain a signal having a predetermined frequency or less. Further, the excitation amplifier has a magnetic field sufficient for detection of the tag 3 by the excitation coils 1a,
1b, the sine wave signal input through a low-pass filter as amplified by the excitation coil 1a,
1b.

On the other hand, a detection unit (not shown) includes the detection coil, a differential amplifier, a notch filter, a band-pass filter, a level firing amplifier, and an analog / digital converter.

The differential amplifier differentially amplifies the signal detected by the detection coil to a degree sufficient for removing unnecessary signals in a subsequent circuit and outputs the amplified signal. The differential amplifier has a well-known circuit configuration. The notch filter is used to remove a carrier component contained in a signal detected by the differentially amplified detection coil. The so-called notch frequency is set to the carrier frequency, and the pulse generated by the tag 3 is generated. The configuration is such that only signal components are output. Further, the band-pass filter is a publicly-known one and is for removing unnecessary high-frequency and low-frequency components from a signal obtained through a notch filter. Further, the level adjusting amplifier is for amplifying the signal obtained from the band-pass filter to a level necessary for inputting the signal obtained from the band-pass filter to the subsequent analog-digital converter, and outputting the amplified signal.

The control unit performs signal processing on the signal input from the detection unit to determine the passage of the tag 3 between the excitation coil and the detection coil, and performs notification by the notification unit as necessary. , The excitation coils 1a, 1
It is configured to excite b. The notification unit performs a notification operation in response to a signal from the control unit when the control unit detects the passage of the tag 3, and for example, sounds a notification buzzer.

As shown in FIGS. 1 to 4, the one excitation coil 1a (left side in FIGS. 1 to 4) has a current in one direction (clockwise in FIG. 2) in the Y direction and the Z direction, respectively. Flowing main coil 4 and central merging channel 5a
The auxiliary coil 5 formed by connecting the outer path 5b through which current flows clockwise (FIG. 2) and the outer path 5c through which current flows counterclockwise (FIG. 2) from both sides is denoted by reference characters a, b, d, and The four corners indicated by c are superimposed on the four corners indicated by symbols G, H, J and I. The other exciting coil 1b is connected to a main coil 6 through which current flows in the same direction as the main coil 4 of the exciting coil 1a.
And an auxiliary coil 7 formed by connecting an outer path 7b through which a current flows clockwise (FIG. 2) to a central merging path 7a and an outer path 7c through which a current flows counterclockwise from both sides.
The four corners indicated by D and C are superimposed on the four corners indicated by symbols g, h, j and i. And these exciting coils 1a, 1b
Is formed as the gate 2 through which the tag 3 passes as described above.

As can be understood from FIG.
The flow of the current having the exciting effect of a, 1b is a → E → F →
b → a, and the flow of the current having the exciting effect of the exciting coil 1b is C → e → f → D → C. Therefore, FIG.
When the magnitudes of the currents of the main coils 4 and 6 and the auxiliary coils 5 and 7 are different from each other, the electromagnetic waves excited by the current in the gate 2 between the exciting coils 1a and 1b effectively cancel each other in the X direction. Although there is a part, the detection of the tag 3 does not hinder since this part is shifted. On the other hand, when the magnitudes of the currents shown in FIG.
There is no portion where the electromagnetic waves cancel each other in each of the Y and Z directions. In FIGS. 3 and 4, white arrows indicate the direction of the magnetic field, and wide arrows indicate the direction of the electromagnetic waves.

When a product with a tag 3 passes through the gate 2, for example, a change in magnetic flux density generated by the tag 3 due to electromagnetic waves generated by the excitation coils 1a and 1b is detected by a detection coil (not shown). However, by determining that the magnetic field is from the tag 2 under predetermined conditions, it is possible to prevent theft of goods or the like in a store or the like.

It should be noted that the present invention is not limited to the above-described embodiment, and a portion in which a current flows in the same direction in the horizontal Y direction and the vertical Z direction in parallel with the moving direction of the article to which the tag 3 is attached. And a pair of exciting coils each having a portion in which current flows in a different direction overlapped with each other, with a predetermined interval so that a portion in which current flows in the same direction and a portion in different directions face each other. For example, FIG. 5 is a development view of the excitation coils 100a and 100b as viewed from the inside of the gate. To form the gate, reference numerals M, N, O, P
And four corners indicated by reference numerals m, n, o, and p).
0b, and FIG. 6 (excitation coils 200a, 200c).
0b is an exploded view of the gate as viewed from the inside. In order to form the gate, four corners indicated by reference numerals S, T, U, V and four corners indicated by reference numerals s, t, u, v face each other. (Disposed) may be used as the excitation coils 200a and 200b. The present invention may be used not only for preventing theft of merchandise in a store as in the above embodiment, but also for preventing theft of art in an art museum.

[0021]

As described above, according to the first aspect of the present invention, the electromagnetic waves excited by the pair of exciting coils are in the X direction and the Y direction.
Since the tag exists in both the direction and the Z direction, even if the tag passes through any part of the gate, it can be detected, and the movement of the article can be surely monitored.

According to a second aspect of the present invention, there is provided an exciting coil comprising a main coil through which a current flows in one direction, and an auxiliary coil formed by connecting an outer path to a central merging path from both sides. An excitation coil formed by superimposing an auxiliary coil formed by connecting an outer path to a central merging flow path from both sides and a main coil in which a current flows in a direction opposite to the current direction of the main coil of the excitation coil has a current flowing in the same direction. Are arranged at a predetermined interval so that the part flowing in a different direction from the part flowing in the opposite direction, the electromagnetic wave excited by the pair of exciting coils is X
Since the tag exists in any of the directions, the Y direction, and the Z direction, the tag can be detected even if the tag passes through any part of the gate, and the movement of the article can be monitored more reliably. This has the effect.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an exciting coil.

FIG. 2 is a developed view of the two excitation coils as viewed from inside a gate.

FIG. 3 is a schematic diagram of a gate showing the direction of an electromagnetic wave when the magnitude of current of the main coil and that of the auxiliary coil are different, as viewed from above.

FIG. 4 is a schematic view of a gate showing the outline of electromagnetic waves when the magnitudes of currents of a main coil and an auxiliary coil are the same, as viewed from above.

FIG. 5 is an expanded view of an excitation coil and a detection coil according to another embodiment as viewed from the inside of a gate.

FIG. 6 is a developed view of an excitation coil and a detection coil according to another embodiment as viewed from the inside of a gate.

FIG. 7 is a perspective view of an exciting coil in a first conventional example.

FIG. 8 is a schematic view of a gate showing a direction of an electromagnetic wave in the first conventional example, as viewed from above.

FIG. 9 is a schematic diagram similarly viewed from the front.

FIG. 10 is a perspective view of an exciting coil in a second conventional example.

FIG. 11 is a schematic view of a gate showing a direction of an electromagnetic wave in a second conventional example as viewed from above.

FIG. 12 is a schematic diagram similarly viewed from the front.

[Explanation of symbols]

 1a, 1b Exciting coil 2 Gate 3 Tag 4 Main coil 5 Auxiliary coil 5a Merging path 5b, 5c Outer path 6 Main coil 7 Auxiliary coil 7a Merging path 7b, 7c Outer path 100a, 100b Exciting coil 200a, 200b Exciting coil

Claims (2)

[Claims] 1. A method according to claim 1, wherein a signal resulting from the change in the magnetic flux density of the magnetic member that is changed by being exposed to a magnetic field is obtained by a detection coil, and the signal is compared with a predetermined value. A magnetic article monitoring device for detecting the presence or absence of a tag provided with the magnetic member, wherein a current flows in the same direction in a horizontal Y direction and a vertical Z direction parallel to the moving direction of the tagged article. A pair of exciting coils formed by superimposing two coils each having a portion and a portion through which current flows in a different direction,
A portion where a current flows in the same direction and a portion that flows in a different direction are arranged at a predetermined interval so as to face each other, and a gate through which a tag passes between both coils is formed. The gate generates a magnetic field generated by each of the exciting coils. A magnetic article monitoring apparatus provided with a detection coil for detecting that the magnetic flux density of the tag has changed by passing through the tag. 2. A method according to claim 1, wherein a signal resulting from the change in the magnetic flux density of the magnetic member that is changed by being exposed to the magnetic field is obtained by a detection coil, and the signal is compared with a predetermined value. A magnetic article monitoring apparatus for detecting the presence or absence of a tag provided with the magnetic member, wherein current flows in one direction in each of a horizontal Y direction and a vertical Z direction parallel to a moving direction of the article with the tag. An excitation coil formed by superposing an auxiliary coil formed by connecting an outer path to a central merging flow path from both sides of the main coil, and a main coil in which a current flows in a direction opposite to a current direction of the main coil of the excitation coil. The excitation coil, which is formed by superimposing an auxiliary coil formed by connecting the outer path from both sides to the combined flow path, is set in such a manner that a part where current flows in the same direction and a part that flows in a different direction face each other. Arranged at an interval, a gate through which the tag passes between both coils was provided, and a detection coil for detecting that the magnetic field magnetic flux density generated by each of the exciting coils was changed by passing through the tag was provided at this gate. Magnetic article monitoring device.