JP2001028510A - Antenna for data carrier and data carrier using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna that the communication distance is prevented from being short, even when a plurality of data carriers come close to each other and operate side by side. SOLUTION: The basic structure of this antenna comprises an air core coil 10, rolled in a planar manner and a plate magnetic core 11 inserted into the coil 10 almost in parallel with the plane of the coil 10, and metal foils 17 and 18 are pasted to at least one side of the surfaces of the coil 10. Thus, it is possible to prevent a magnetic field generated by a self-antenna from being negated by a magnetic field generated by current introduced by an adjacent antenna for data carriers and a communication distance of when a data carrier approaches a metallic object from being short by reducing electromagnetic connection with the surrounding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data carrier antenna and a data carrier using the same.
A data carrier that receives an alternating magnetic field supplied from a master unit by a built-in antenna, uses a voltage induced by the antenna as an operation power source, and operates based on a modulation signal applied to the alternating magnetic field transmitted from the master unit. The present invention relates to an improvement of an antenna used for the above.

[0002]

2. Description of the Related Art A data carrier system comprising a data carrier (slave unit) in which an IC chip is arranged on a plastic card and an interrogator (master unit) for supplying an alternating magnetic field to the data carrier wirelessly is known. It is becoming popular.

Such a data carrier system includes a non-contact type ID card as a railway commuter pass, a tag for identifying individual cargo in the logistics field, a product inventory management at various manufacturers, an office or a hospital or the like. Is used for file management and so on.

As described above, data carriers are widely used in various fields. In a non-contact type data carrier, the power used by itself is obtained from an alternating magnetic field supplied from an interrogator. .

That is, a non-contact type data carrier has an antenna, receives an alternating magnetic field transmitted from a device called an interrogator or a base unit by the antenna, and flows according to the magnitude of the alternating magnetic field. The current is rectified into operating power.

As a conventional example of an antenna provided on such a data carrier, for example, Japanese Patent Application No. 10-2176 is disclosed.
There is an antenna proposed in No. 33 (data carrier and data carrier antenna).

[0007]

In the application of a data carrier, there is a case where one master unit communicates with many data carriers in a service area. In such a case, especially when a large number of data carriers are present at the same location, the data carriers may be in close contact with each other. This will be described with reference to FIG.

When a plurality of data carriers are placed in close contact with each other, the mutual relationship between the data carriers is shown in FIG.
(A) or FIG. 6 (B). That is, in FIG. 6A, the direction of each data carrier is reversed in order, but in FIG. 6B, each data carrier is placed in the same direction.

When a large number of data carriers are placed, the master unit supplies a strong alternating magnetic field so that the large number of data carriers existing in the service area can be driven simultaneously and sufficiently. However, even when an intense alternating magnetic field is supplied, inoperable data carriers may be generated if many data carriers are in close contact.

This is because, when receiving an alternating magnetic field from the master unit, an induced current flows through an antenna coil incorporated in each data carrier, and a magnetic field newly generated thereby adversely affects the operation of the data carrier. .

That is, as shown in FIG. 6A, if the directions of a large number of data carriers are reversed in order, the magnetic field newly generated by the induced current flowing through the antenna coil induces the antenna of the adjacent data carrier. There is no problem because it does not act to cancel the current (operating voltage) that is applied.

However, as shown in FIG. 6B, when the antenna coils of a large number of data carriers have the same orientation, the magnetic field newly generated by the induced current flowing through each antenna coil causes the antennas of the adjacent data carriers to have the same orientation. In this case, the current (operating voltage) induced in the data carrier acts to cancel out, so that the data carrier near the center cannot obtain the required operating power and cannot operate.

For this reason, conventionally, it has been necessary to provide a stronger magnetic field by the master unit, or to increase the interval without closely contacting the data carriers. Therefore, there is a problem that the number of data carriers that can simultaneously communicate within the same service area is reduced.

In the application of the data carrier, the data carrier is often attached to the object to be managed. At this time, the object to be managed may be a metal product or may be arranged on a metal table or tray. In this case, the tuning of the antenna coil incorporated in the data carrier shifts or the loss increases, and there is a disadvantage that the communication distance becomes extremely short.

The present invention has been made in view of the above problems, and has been described with reference to the accompanying drawings.
A first object is to prevent the communication distance of each data carrier from being extremely reduced. It is a second object of the present invention to prevent the communication distance from being reduced when the data carrier is brought closer to a metal object.

[0016]

An antenna for a data carrier according to the present invention is inserted into an air-core coil wound in a planar shape and inserted into the air-core coil so as to be substantially parallel to the plane of the air-core coil. A data carrier antenna having a plate-shaped magnetic core, wherein at least one surface of the air-core coil is provided with a metal foil. Also,
Another feature of the data carrier antenna of the present invention is that the metal foil is disposed so as to substantially shield the entire air-core coil when viewed from the plane. Another feature of the data carrier antenna of the present invention is that the air-core coil wound in a planar shape and the air-core coil inserted into the air-core coil so as to be substantially parallel to the plane of the air-core coil. A data carrier antenna comprising a plate-shaped magnetic core having a size allowing insertion of the plate-shaped magnetic core in parallel with the air-core coil, and a planar shape of the air-core coil. The length in one direction in the width of the plate-shaped magnetic core is as close as possible to the length in the width direction, and the length in the other direction perpendicular to the one-side direction is the length of the plate-shaped magnetic core. The length is as close as possible to the thickness. Another feature of the data carrier antenna of the present invention is that the planar shape of the air-core coil is any one of an ellipse, an ellipse, and a rectangle. Another feature of the data carrier antenna of the present invention is that the plate-shaped magnetic core is a single plate-shaped magnetic core.
Another feature of the data carrier antenna of the present invention is that the plate-shaped magnetic core is inserted into the air-core coil so as to be substantially parallel to the plane of the air-core coil. It is characterized by being made of a plate-shaped magnetic core. Another feature of the data carrier antenna of the present invention is that the plate-shaped magnetic core is made of an amorphous metal. Another feature of the data carrier antenna of the present invention is that the plate-shaped magnetic core is a unidirectional silicon steel plate, and the plate-shaped magnetic core and the goth orientation are the axes of the air-core coil. It is characterized by being arranged so as to face the core direction.

The data carrier according to the present invention is characterized in that:
9. The antenna for a data carrier according to any one of items 8 to 8, wherein:

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a data carrier antenna according to the present invention; FIG. 1 is an exploded perspective view showing a main part of the data carrier antenna according to the first embodiment. FIG. 2 is a cross-sectional view of the data carrier antenna shown in FIG. 1 along the longitudinal direction.

In FIG. 1, a plate-shaped magnetic core 11 is inserted into an air-core coil 10 wound in a planar shape so as to be substantially parallel to the plane of the air-core coil 10, so that a basic data carrier antenna is provided. The structure is configured.

An IC chip 13, a tuning capacitor 14, and the like are incorporated in a data carrier module 12 that operates by being supplied with operating power from the data carrier antenna. Then, insulating sheets 15 and 16 are provided so as to sandwich the data carrier antenna and the data carrier module 12 from both sides, and metal foils 17 and 18 are attached to both outer sides thereof. The above metal foil 1
Aluminum or copper can be used as the material of 7 and 18.

Many air core coils 10 as described above are commercially available, and an air core coil having an arbitrary shape and size can be selected according to design requirements. Since the configuration can be achieved simply by inserting the plate-shaped magnetic core 11 into the general-purpose air-core coil, the basic configuration of the data carrier antenna according to the present embodiment is easy to manufacture and reduces the manufacturing cost. Can be. The plate-shaped magnetic core 11 can be formed by cutting, for example, an amorphous sheet into a predetermined size and winding an insulating sheet around it.

Next, an example in which a plurality of data carriers are closely arranged will be described with reference to FIG. Although FIG. 3 shows a state in which nine data carriers are arranged, in practice, tens to hundreds of data carriers may be arranged.

When the air-core coil 10 of each data carrier and the plate-shaped magnetic core 11 are arranged as shown in FIG. 3, when a magnetic field along the longitudinal direction of the plate-shaped magnetic core 11 is applied, the air-core An induction current flows through the coil 10. With this induced current,
A magnetic field is generated in a direction obtained by combining the direction of the magnetic core and the direction perpendicular to the plane of the coil.

Due to the magnetic field generated by the induced current, the longitudinal component of the magnetic core of the magnetic field is slightly weakened. Further, a magnetic field having a component perpendicular to the plane of the air core coil 10 is newly generated. However, an induced current flows through the metal foils 17 and 18 under the magnetic field of the component in this direction,
The component in this direction is weakened because the induced current cancels the magnetic field. This effect will be described below with reference to measurement examples.

FIG. 3A shows a case where nine data carriers are arranged side by side in the same direction, and FIG.
This shows a case where a plurality of data carriers are alternately arranged in the opposite direction. The results of measuring the operating voltages of these data carriers are shown in Table 1 below. Table 1 below
Shows an example in which five data carriers (No. 1 to No. 5) are arranged and operated.

[0026]

[Table 1]

The data carrier used for measuring the operating voltage operates at an operating voltage of 2.4 V or more. Also, since a regulator is provided inside, 3.
It has the characteristic that the voltage does not rise so much above about 0V.

When a plurality of data carriers are arranged in the same direction without the metal foils 17 and 18, the electromotive voltage of the data carrier near the center decreases (in this example, 1.1V to 1.1V).
1.5V). As a result, if five or more data carriers are arranged in close contact, the data carrier arranged at the center cannot operate.

However, even if a plurality of data carriers are arranged in the same direction, the operating voltage is stable if the metal foils 17 and 18 are provided. In particular, it was found that the effect of applying a magnetic field from the longitudinal direction of the plate-shaped magnetic core 11 was great.

This is because the metal foils 17, 1 and
Since 8 is parallel, no induced current flows, so that the driving magnetic field is not weakened by the metal foils 17 and 18.
A metal foil 17 between the air-core coil 10 and
This is because the presence of 18 reduces the phenomenon that the air-core coils 10 are coupled to each other and the electromotive voltage drops.

On the other hand, with respect to the magnetic field from the direction perpendicular to the surface of the air core coil 10, the electromotive voltage is reduced to 1/3 or less. The size of the metal foils 17 and 18 is desirably slightly larger than that of the air core coil 10 in order to reduce the coupling between the data carriers.

In the case of a limited application in which the data carriers are arranged side by side so that the directions of the data carriers are alternately reversed, it is better that there is no metal foil. However, it is very difficult to arrange the data carriers in the same direction, and it is difficult to know the order. Therefore, in the case of general application, it is better to attach the metal foils 17 and 18 to obtain a better result.

FIG. 4 shows a second embodiment of the present invention. In the embodiment shown in FIG.
Instead of being provided outside the zero, the area of the air core coil 10 is made as small as possible.

That is, assuming that a circular air-core coil having a normal size is shown in FIG. 4C, the air-core coil 20 of the present embodiment has a length in one side direction in a plane shape thereof. Is set as close as possible to the length in the width direction of the plate-shaped magnetic core 11. Further, the length in the other side direction orthogonal to the one side direction is a length as close as possible to the thickness of the plate-shaped magnetic core 11. By having such a length, the air-core coil 20 of the present embodiment eventually has an elliptical, elliptical or square planar shape.

When the air-core coil 20 is configured to have the shape and size as in the present embodiment, interference with the surroundings can be reduced. Can be satisfactorily operated even when is a metal product. Table 2 below shows operating voltages when the data carrier according to the present embodiment is independently brought close to a metal plate.

[0036]

[Table 2]

As in the present embodiment, when the air-core coil 20 has an elliptical outer shape to reduce its plane area, it operates even if it is close to a metal plate (copper) up to 1 mm. It only worked up to 2 mm. On the other hand, for a magnetic field in a direction perpendicular to the plane of the coil, the operating voltage is １ ／.
It has fallen to the extent.

In the case of this embodiment, the interference between data carriers could not be eliminated as much as the example shown in FIG. 1, but the characteristic deterioration at the time of sticking to metal can be prevented. Are very effective, and the metal foils 17, 1
8 has the effect of lowering costs than pasting 8.

As described in the present embodiment, the effect described above can be obtained by reducing the area of the air-core coil 20, and the structure can be obtained only by inserting the plate-shaped magnetic core 11 into the air-core coil 20. Since it is possible, the manufacturing becomes easier and the manufacturing cost can be reduced as compared with the case where the coil is wound around the plate-shaped magnetic core 11.

FIG. 5 is a diagram showing a third embodiment. In this embodiment, an air-core coil 30 wound in a planar shape is provided with a plate-shaped magnetic core 11 so that its axis is at a predetermined angle so as to be substantially parallel to the coil surface of the air-core coil 30. A plurality of sheets (three sheets in the example of FIG. 5) are inserted, and metal foils (not shown) are attached to both sides of the surface of the plate-shaped magnetic core 11. Furthermore, this is an example in which the shape of the air core coil 30 is rectangular.

As in the present embodiment, the action of collecting magnetic flux can be improved by inserting a plurality of plate-shaped magnetic cores 11 into the air-core coil 30. This makes it possible to extend the communication distance or to drive the air-core coil 30 with an alternating magnetic field from a wider angle in the plane of the air-core coil 30.

As described above, it is more effective to apply the metal foil to the surface of the coil and to reduce the coupling between the data carrier and the surrounding metal by combining both measures for reducing the area of the coil. . In the above-described embodiment, the metal foils 17 and 18 are used as the air core coils 10 (20, 3).
Although the example in which the data carrier is attached to both surfaces of 0) is shown, the metal foil may be attached to only one surface of the air-core coil in a usage example in which the data carrier can be arranged in a predetermined direction.

In the above-described embodiment, an amorphous metal has been described as an example of the constituent material of the plate-shaped magnetic core 11, but various other materials may be used as the constituent material of the plate-shaped magnetic core 11. Can be used.

For example, an electromagnetic steel sheet (silicon steel sheet) used as a core of a transformer can be used. In this case, it is preferable to use a unidirectional silicon steel plate generally used for a high-frequency transformer or the like, and to make the direction in which the magnetic flux easily passes is directed to the axial direction of the empty coil.

The direction in which the magnetic flux easily passes in the above-mentioned unidirectional silicon steel sheet is generally determined by the Goss orientation which is the direction of crystal grain growth. Therefore, the plate-shaped magnetic core 11 may be arranged such that the Goss direction of the magnetic core 11 is oriented in the axial direction of the air core coil 10 (20, 30) (so that the Goss direction is oriented in the longitudinal direction of the magnetic core plate).

In the above embodiment, the entire surface of the metal foil is shown. However, a partial hole may be formed in the metal foil, or the whole or a part may be formed in a net shape.
In this case, since the surface of the data carrier is not flat, it is possible to obtain an advantage that it is easy to apply when it is difficult to apply the entire metal foil. It can be prevented from lowering.

[0047]

As described above, the antenna for a data carrier according to the present invention has a plate-shaped magnetic core formed on a flat wound air core coil so as to be substantially parallel to the coil surface of the air core coil. One or more cores are inserted so that the axis is at a predetermined angle, and metal foil is attached to at least one of the surfaces of the air-core coil, so that a plurality of data carriers are arranged in close contact with each other. In this case, a metal foil can be interposed between the air-core coils in each data carrier. Thereby, it is possible to prevent a disadvantage that a magnetic field generated by its own antenna is canceled by a magnetic field generated by a current induced to an antenna of an adjacent data carrier, and when a large number of data carriers are present in the same place, The inconvenience of supplying a strong alternating magnetic field or preventing communication with the central data carrier can be reliably prevented.

According to another feature of the present invention, the plate-shaped magnetic core is large enough to be inserted in parallel with the air-core coil, and one side in the plane shape of the air-core coil. The length in the direction is as close as possible to the width in the width direction of the plate-shaped magnetic core, and the length in the other direction orthogonal to the one side direction is the thickness of the plate-shaped magnetic core. Since the length is as close as possible, many air-core coils are commercially available and can be selected in any shape and size according to design requirements. And since it can be constituted only by inserting a plate-shaped magnetic core into the above-mentioned general-purpose air-core coil, the basic structure of the data carrier antenna of the present embodiment is easy to manufacture, and the manufacturing cost can be reduced. it can.

According to another feature of the present invention, the influence of the magnetic field generated by the current induced in the antenna of the adjacent data carrier and the influence of the surrounding metal plate can be minimized. This makes it possible to reduce the mutual coupling between the data carriers while having a simple structure, and to reduce the reduction in the communication distance even when a plurality of data carriers are brought into close contact with each other. Also,
Shortening of the communication distance when the data carrier approaches the metal object can be reduced.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a data carrier, showing an embodiment of a data carrier antenna according to the present invention.

FIG. 2 is a cross-sectional view of the data carrier antenna shown in FIG.

FIG. 3 shows an example in which a plurality of data carriers are arranged in close contact with each other, FIG.
(B) is a figure which shows the example which made the direction of the air core coil the same.

FIG. 4 is a view showing the second embodiment and showing an example in which the plane area of the air-core coil is made as small as possible.

FIG. 5 shows the third embodiment, and is a diagram showing an example in which a plurality of plate-shaped magnetic cores are inserted into an air-core coil.

FIG. 6 is a diagram illustrating a conventional problem.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Air core coil 11 Magnetic core 12 Data carrier module 13 IC chip 14 Tuning capacity 15, 16 Insulation sheet 17, 18 Metal foil 20 Air core coil of 2nd embodiment 30 Air core coil of 3rd embodiment

Claims (9)

[Claims] 1. A data carrier comprising: an air-core coil wound in a planar shape; and a plate-shaped magnetic core inserted into the air-core coil so as to be substantially parallel to the plane of the air-core coil. An antenna for a data carrier, comprising: a metal foil on at least one surface of the air-core coil. 2. The data carrier antenna according to claim 1, wherein the metal foil is disposed so as to substantially shield the entire air-core coil as viewed in a plane direction. 3. A data carrier comprising: an air-core coil wound in a planar shape; and a plate-shaped magnetic core inserted into the air-core coil so as to be substantially parallel to the plane of the air-core coil. An antenna having a size that allows the plate-shaped magnetic core to be inserted in parallel with the air-core coil, and a length in one side in a plane shape of the air-core coil that is equal to the plate-shaped magnetic core. The length in the width direction of the core should be as close as possible, and the length in the other direction perpendicular to the one side direction should be as close as possible to the thickness of the plate-shaped magnetic core. Characteristic data carrier antenna. 4. The data carrier antenna according to claim 3, wherein the planar shape of the air-core coil is one of an ellipse, an ellipse, and a rectangle. 5. The data carrier antenna according to claim 1, wherein the plate-shaped magnetic core is a single plate-shaped magnetic core. 6. The plate-shaped magnetic core includes a plurality of plate-shaped magnetic cores inserted into the air-core coil so as to be substantially parallel to a plane of the air-core coil. Item 1
The antenna for a data carrier according to any one of claims 1 to 4. 7. The data carrier antenna according to claim 1, wherein the plate-shaped magnetic core is made of an amorphous metal. 8. The plate-shaped magnetic core is a unidirectional silicon steel plate, and the plate-shaped magnetic core is disposed so that the goth orientation is oriented in the axial direction of the air-core coil. The data carrier antenna according to any one of claims 1 to 6. 9. A data carrier provided with the data carrier antenna according to claim 1. Description: