JPH1041730A - Mat antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a truck to easily pass on a mat in a mat antenna in which an antenna coil formed like a loop is housed. SOLUTION: This antenna is formed by interposing an antenna coil between a lower sheet 8 and an intermediate sheet 10, filling a space part formed at the inside and outside of the antenna coil 2 between sheets 8 and 10 with protection members 4 and 6, and laminating an upper sheet 12 on the intermediate sheet 10. In this case, the outer periphery of the intermediate sheet 10 is made smaller than the protecting member 6 so that a mat peripheral part is shaped like a ladder, and the upper sheet 12 is inclined along the ladder to the lower sheet 8 side, the they are high frequency welded. As a result, when a truck passes over the mat, a wheel can climb step by step at the stairs part, and the truck can be moved with a small force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mat type antenna which is arranged on a floor at an entrance of a store or the like and emits an electromagnetic wave for activating an anti-theft tag attached to a product.

[0002]

2. Description of the Related Art Conventionally, CDs (Compact Discs)
In stores that sell products that are easily stolen, such as anti-theft tags, which automatically start up when an electromagnetic wave of a predetermined frequency is received and generate an alarm sound, and An antenna that emits electromagnetic waves that activates the tag is installed, and when a person who steals the product passes through the doorway, an electromagnetic sound from the antenna generates an alarm sound from the anti-theft tag to prevent theft of the product Do
Anti-theft systems are widely adopted.

As an antenna used in such an anti-theft system, for example, Japanese Utility Model Laid-Open No. 4-933 has been proposed.
As disclosed in Japanese Unexamined Patent Publication No. 88, the antenna coil formed in a loop shape is housed inside a flat mat formed of a soft material such as a natural resin or a synthetic resin, so that a floor surface of a doorway of a store can be obtained. There is known a mat type antenna which can be arranged as it is.

[0004] In this type of mat type antenna,
To make it easy for vehicles like wagons and wheelbarrows to get over,
The periphery of the mat is inclined by a mold used during the molding of the mat or a cutting process after the molding.

[0005]

However, the mat type antenna is required to have a certain thickness since the antenna coil is housed in the mat and protected from a load applied from above the mat. When it is arranged on the floor, the step with the floor becomes large. Therefore, there has been a problem that the kinetic energy required for the bogie to climb over the mat is large only by inclining the periphery of the mat as in the prior art, and a large force is required to move the bogie.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and in a mat type antenna having an antenna coil housed therein, the force required for the bogie to climb over the mat is reduced so that the bogie can easily move on the mat. The purpose is to be able to pass.

[0007]

According to a first aspect of the present invention, there is provided an antenna coil having an antenna wire formed in a loop shape, and an antenna coil housed therein. And a plate-shaped protection member that protects the loop shape, wherein the peripheral edge of the protection member is directed upward by a predetermined angle from the floor surface side on which the mat type antenna is installed to the inside of the mat. At the same time, an upper sheet and a lower sheet made of a soft material are laminated on the upper surface and the lower surface side of the antenna coil and the protection member, respectively, and further, along the steps of the periphery of the protection member. The upper sheet is inclined to the lower sheet and the respective sheets are joined to each other.

As described above, in the mat type antenna of the present invention, instead of integrally forming the entire mat with a soft material as in the conventional case, a protective member containing an antenna coil therein and an upper surface and a lower surface thereof are provided. The protective member is composed of an upper sheet and a lower sheet that are respectively laminated, the peripheral edge of the protection member is formed in a step shape, and the step edge is covered with the upper sheet.

Therefore, according to the present invention, the appearance is a mat with a sloping edge like the conventional mat type antenna, but when the bogie crosses the mat, the wheels are attached to the rim of the protection member inside the mat. Since the formed stairs need only be raised one by one, the kinetic energy required to get over the mat can be reduced, and the worker who moves the cart can easily move the cart. Also, when the truck descends from the mat to the floor, the stairs may be lowered one by one, so that the operator can slowly descend the truck from above the mat.

Next, a second aspect of the present invention is the first aspect.
In the mat type antenna according to the above, the protection member,
A pair of protection members having substantially the same thickness as the antenna coil and disposed inside and outside a loop formed by the antenna coil, respectively, the pair of protection members and the antenna coil, and the upper sheet; And an intermediate sheet having a predetermined thickness, and the outer circumference of the intermediate sheet is made smaller than the outer circumference of a member disposed outside the antenna coil, so that the outer circumference has a two-stage step shape. It is characterized by being formed in.

That is, the protective member according to the first aspect may be integrally formed of resin or the like in a state where the antenna coil is housed, as in a conventional mat type antenna.
As described in claim 2, a pair of protection members are provided inside and outside the loop of the antenna coil, and an intermediate sheet having an outer periphery smaller than the outer periphery of the protection member is further laminated thereon. You may. If the protection member is configured in this manner, it is not necessary to mold the protection member in a state where the antenna coil is disposed inside, so that the production of the protection member is simplified, and the inclination of the step portion around the mat is reduced by the intermediate sheet. The design can be easily changed because the size can be changed as appropriate. In this case, if a plurality of intermediate sheets are used, and the outer periphery of each intermediate sheet becomes smaller toward the upper side of the mat, the number of steps on the periphery of the mat can be increased.

[0012] On the other hand, the invention according to claim 3 is based on claim 1.
Alternatively, in the mat type antenna according to claim 2, the antenna coil is a hollow plate-shaped antenna in which an antenna wire is wound in a flat spiral shape. That is, in the case of the mat type antenna, if a loop antenna having only one turn of the antenna wire is used for the antenna coil, good output (radiated power) may not be obtained. Therefore, in the present invention (claim 3), good output characteristics can be obtained by using an antenna coil having a hollow plate shape by winding an antenna wire in a flat spiral shape for an antenna element. .

[0013]

Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 1 is an exploded perspective view showing a configuration of a mat type antenna according to an embodiment to which the present invention is applied, and FIG. 2 is a partially cutaway plan view showing a configuration of the mat type antenna according to the embodiment. .

As is apparent from FIGS. 1 and 2, the mat type antenna of this embodiment has an antenna coil 2 formed in a hollow plate shape by winding an antenna wire in a flat spiral shape as an antenna element. This is provided inside the mat. That is, the mat type antenna according to the present embodiment has the antenna coil 2 and the plate thickness substantially the same as the antenna coil 2, and is disposed in the hollow portion and the outer peripheral portion of the antenna coil 2 to prevent the deformation of the antenna coil 2. And a pair of protection members 4 and 6 for use. The antenna coil 2 and the protection members 4 and 6 are stacked on the upper surface of the lower sheet 8 having a predetermined thickness. Also, the antenna coil 2
On the upper surfaces of the protective members 4 and 6, an intermediate sheet 10 capable of covering the entire upper surface is laminated, and further thereon, an upper sheet 12 is laminated.

That is, the mat type antenna of this embodiment is
The antenna coil 2 is sandwiched between the lower sheet 8 and the intermediate sheet 10, and a space formed between the sheets 8 and 10 inside and outside the antenna coil 2 is
Fill with protective members 4 and 6 that will be the inner and outer frames,
It is produced by laminating the upper sheet 12 on the intermediate sheet 10.

Here, the antenna coil 2 is a covered wire in which a conductive wire is covered with an insulating material, for example, a vinyl wire for heat-resistant equipment wiring in which a stranded wire made of tinned annealed copper is covered with heat-resistant vinyl chloride. This is wound many times in a flat square spiral, and a trapezoidal adhesive sheet 2a is adhered to each side (four sides) of the upper surface and lower surface of the spiral to form a hollow square spiral. It is formed in a plate shape (see FIG. 1).

A power supply conductive plate 2b made of a thin copper plate is connected to an end of the antenna wire located inside the spiral of the antenna coil 2 by soldering or the like (FIG. 2).
reference). The conductive plate 2b is for supplying a transmission signal from the outside of the helix of the antenna coil 2 to the end of the antenna wire located inside, and has an effect on the radiation characteristics of radio waves from the antenna coil 2 to the upper side of the mat. Is arranged between the antenna coil 2 and the lower sheet 8 so as to reduce the number of the sheets. An antenna wire for feeding power is connected to the tip of the conductive plate 2b drawn out of the spiral of the antenna coil 2 by soldering or the like.

The power supply to the antenna coil 2 is shown in FIG.
As shown in the figure, the terminals 1 for power supply are respectively provided at the end of the antenna wire connected to the conductive plate 2b outside the spiral of the antenna coil 2 and at the end of the antenna wire located outside the spiral.
4a, 14b are provided, and transmission signal lines 16a, 16b from a transmitter (not shown) are connected to these terminals to supply a transmission signal (sine wave of a predetermined frequency) from the transmitter. A heat-shrinkable tube is provided around the power supply terminals 14a and 14b. After connecting the transmission signal lines 16a and 16b, the tubes are overheated and shrunk so that the connection portion is made of water or the like. To be protected from

On the other hand, the protective members 4 and 6, the lower sheet 8, and the upper sheet 12 have a predetermined thickness (for example, a predetermined thickness, for example, in order to absorb an impact applied to the antenna coil 2 when a person or a trolley passes on the mat. Lower sheet 8 and upper sheet 12 are 2m
m, the protection members 4 and 6 are made of a soft synthetic resin having a thickness of 2.5 mm corresponding to the antenna wire forming the antenna coil 2, for example, polyvinyl chloride (PVC).

The intermediate sheet 10 is also for absorbing the shock applied to the antenna coil 2 from above the mat, but in this embodiment, the same PVC as the upper sheet 12 and the like is used.
Sheet body 10b of a predetermined thickness (for example, the same thickness of 2 mm as upper sheet 12) made of a soft synthetic resin such as
In addition, a synthetic resin harder than the sheet body 10b, for example,
It is manufactured by laminating a thin film-shaped (for example, 0.5 mm-thick) sheet material 10a made of polyethylene terephthalate (PET), polycarbonate (PC), or the like (see FIG. 3A). The intermediate sheet 10 is laminated between these parts and the upper sheet 12 with the hard film-shaped sheet material 10 a facing the antenna coil 2 and the protection members 4 and 6.

In this embodiment, the lower sheet 8,
Antenna coil 2, protective members 4, 6, intermediate sheet 1
0, when the upper sheet 12 is sequentially laminated, these laminated surfaces are joined to each other with a double-sided adhesive tape or an adhesive, and this joining prevents a displacement of the laminated portion in the surface direction. .

As shown in FIG. 3 (a), the outer periphery of the intermediate sheet 10 is smaller than the outer periphery of the protection member 6 arranged on the periphery of the antenna coil 2. At the peripheral edge, a stair is formed in a direction ascending above the mat from the floor surface. Further, at the periphery of the mat, the upper sheet 12 is inclined toward the lower sheet 8 along the steps formed by the intermediate sheet 10 and the protection member 6, and the periphery thereof is joined to the lower sheet 8.

This joining is performed by the lower sheet 8, the antenna coil 2, the protection members 4 and 6, and the intermediate sheet 10
And the upper sheet 12 are laminated as described above, and the laminate is placed on the bed portion 18 of the high frequency welding machine with the lower sheet 8 facing down, and the upper sheet 12 is hung on the lower sheet 8 side, High frequency welding is performed by pressing the upper mold 19 of the high frequency welding machine from above and passing a high frequency of, for example, 27 MHz through the bed 18 and the upper mold 19.

As a result, as shown in FIG. 3 (a), the upper sheet 12 and the lower sheet 8 are closed in a bag shape at the periphery thereof, and the antenna coil 2, the protection member 6, and the intermediate sheet 10 are closed. It is in a state of being stored in a flat bag composed of the sheet 12 and the lower sheet 8.

The upper sheet 12 and the lower sheet 8 are joined by high-frequency welding at the periphery of the mat as described above. As shown in FIG. Is shaped into the mat by high frequency welding. And
After connecting the transmission signal lines 16a and 16b from the transmitter to the terminal of the antenna line drawn out from the antenna coil 2 via the power supply terminals 14a and 14b, A pair of sandwiching plates 24 and 26 for protecting the outside from outside are screwed.

When the mat type antenna manufactured as described above is placed on the floor, water that is sprayed for cleaning or rainwater attached to an umbrella enters the antenna coil 2 by a bag-like shape around the mat. Due to the structure, it can be reliably prevented. As described above, in the mat type antenna of the present embodiment, the antenna coil 2 in which the antenna wire is spirally wound is used as an antenna element for radiating radio waves. The antenna coil 2 is connected to the protection members 4, 6
And the intermediate sheet 10, together with the lower sheet 8 and the upper sheet 12, are firmly stored inside the bag, and are protected from the load and impact applied from above the mat by these parts. Therefore, compared to a general mat type antenna using a loop antenna in which an antenna wire is formed in a single-turn loop as an antenna element, radiation characteristics of electromagnetic waves can be improved without lowering load resistance.

In this embodiment, the upper sheet 12 and the lower sheet 8 are joined by high-frequency welding at the periphery of the mat, so that the periphery of the mat is inclined. 10 form an ascending staircase. For this reason, in the mat type antenna of the present embodiment, the appearance is a mat with a sloping edge like the conventional mat type antenna. However, when the bogie gets over the mat, the weight of the wheels causes the upper sheet 12 to move. The deflection and wheels will rise one step at a time along the internal steps. Therefore, the worker who moves the cart only needs to raise the wheels one by one along the steps inside the mat. As a result, according to the present embodiment, the kinetic energy required to get over the mat can be reduced as compared with the conventional mat type antenna, and the operator can easily move the cart. Also, when the truck descends from the mat to the floor, the wheels may be lowered one by one along the steps formed inside the mat, so that the operator can slowly descend the truck from above the mat.

As described above, one embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and various embodiments can be adopted. For example, in the above embodiment, the protection members 4, 6, the lower sheet 8, the upper sheet 12,
The sheet body 10b of the intermediate sheet 10 is made of soft and elastic PVC. However, these parts may be made of soft synthetic resin other than PVC, natural rubber or synthetic rubber. Can also be used. The reason that these parts are made of a soft material is to prevent an impact load from being directly applied to the antenna coil 2 from above.
Only the soft material may be used, and the other parts may be made of, for example, hard plastic. However, in this case, since the mat type antenna cannot be wound or folded, handling becomes inconvenient.

In the above embodiment, the intermediate sheet 10
A hard sheet material 10a is laminated on a soft sheet main body 10b. This is because the upper surface of the antenna coil 2 is covered with the hard sheet material 10a, so that the antenna coil is placed above the mat. This is to prevent the load applied to the antenna coil 2 from being disperse | distributed reliably, and to prevent the antenna wire of the antenna coil 2 wound spirally from moving in a mat, and to reduce the radiation characteristic of an electromagnetic wave, or to break an antenna wire. is there. Accordingly, if the load resistance of the mat can be ensured by the upper sheet 12 and the sheet body 10b of the intermediate sheet 10, the intermediate sheet 10 may be constituted only by the sheet body 10b. However, in this case, in order to ensure the load resistance of the mat, the sheet body 10b of the upper sheet 12 and the intermediate sheet 10 needs to be thick. If the load resistance of the mat can be ensured only by the upper sheet 12, the intermediate sheet 10 can be eliminated. In this case, the protection member 6 may be formed in a multi-layered structure, and the outer circumference may be smaller for the upper protection member.

Next, in the above embodiment, the intermediate sheet 10
Has been described as forming an ascending staircase inside the periphery of the mat by making the outer periphery of the protective member 6 smaller than the outer periphery of the protective member 6. In this case, as shown in FIG. If the periphery of the member 6 is inclined so that the outer periphery becomes smaller as it goes upward, the carriage can be raised and lowered more smoothly.

Further, as shown in FIG. 5 (b), when the peripheral edge of the protective member 6 is brought into close contact with the joint between the upper sheet 12 and the lower sheet 8, the upper sheet 12 and the lower sheet 8 are formed.
Since the air layer formed inside the joint (that is, the front end of the mat) with the mat can be eliminated, the strength of the front end of the mat can be increased, and the front end of the mat can be prevented from being damaged by passage of a bogie or the like.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view illustrating a configuration of a mat type antenna according to an embodiment.

FIG. 2 is a partially cutaway plan view of the mat type antenna according to the embodiment.

FIG. 3 is an explanatory diagram illustrating a bonding state of a peripheral portion of the mat type antenna according to the embodiment.

FIG. 4 is an explanatory diagram illustrating a shape of a power supply unit from which an antenna wire is drawn out of an antenna coil and a sandwiching plate for protecting the power supply unit.

FIG. 5 is an explanatory diagram illustrating a cross-sectional shape of a periphery of a mat type antenna in which the periphery of a protective member and an intermediate sheet is inclined.

[Explanation of symbols]

2: Antenna coil 2a: Adhesive sheet 2b: Conductive plate 4, 6: Protective member 8: Lower sheet 10: Intermediate sheet 10a: Sheet material 10b: Sheet body 12: Upper sheet 14a, 14b: Terminals (for power supply) 16a, 16b …
Transmission signal line 22: power supply unit 24, 26: sandwiching plate

Claims (3)

[Claims] 1. A mat-type antenna comprising: an antenna coil having an antenna wire formed in a loop shape; and a plate-shaped protection member for storing the antenna coil therein to protect the loop shape. The peripheral edge of the member is formed in a stepped shape inclined at a predetermined angle toward the inside of the mat upward from the floor side on which the mat type antenna is installed, and on the upper and lower sides of the antenna coil and the protection member. ,
A mat, wherein an upper sheet and a lower sheet made of a soft material are laminated, respectively, and furthermore, the upper sheet is inclined to the lower sheet along the steps of the periphery of the protective member, and the respective sheets are joined to each other. Type antenna. 2. The protection member has substantially the same thickness as the antenna coil, a pair of protection members disposed inside and outside a loop formed by the antenna coil, respectively, and the pair of protection members. And an intermediate sheet disposed between the antenna coil and the upper sheet and having a predetermined plate thickness. The outer periphery of the intermediate sheet is made smaller than the outer periphery of a member disposed outside the antenna coil. The mat type antenna according to claim 1, wherein the outer periphery is formed in a two-step shape. 3. The mat-type antenna according to claim 1, wherein the antenna coil is a hollow plate-shaped antenna in which an antenna wire is wound in a flat spiral shape.