JPH0622307B2 - Combined LC resonant circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates generally to electrical resonant circuits,
Particularly, it relates to a planar resonance circuit. Furthermore, the present invention relates to a resonance circuit tag which is a small and high-performance resonance circuit and is used as a shoplifting prevention device in a supermarket as an application example.

[Prior Art] Resonant circuits related to electricity have many applications and are generally used in the field of radio waves such as radio and television. These are usually composed of a cylindrical coil and an independent separate capacitor, and although they are miniaturized, they are three-dimensional ones having a considerable size.

On the other hand, this resonant circuit is also used in shoplifting prevention devices in supermarkets. This uses a tag-shaped resonance circuit that resonates with a preset type or signal radio wave, and is a planar, low-cost, disposable one.

In the latter case as well as in the former case, the coil and the capacitor were separately configured. In order to make this easier to understand, the latter example will be illustrated and described.

FIG. 1 relates to a combined LC resonance circuit according to the present invention, and will be described later. First, FIG. 2 is a plan view of an embodiment of a conventional tag-shaped resonance circuit. This is the third
Insulating film 1
One surface 3 of the coil 2 and one of the electrodes 3a and 4a of each capacitor provided on both ends of the coil 2
And as shown in Fig. 4 on the reverse side (ie, this bottom view), the poles 3a and 4a of the above-mentioned capacitors respectively.
Of the other capacitor 3b and 4b and a circuit 5 connecting both poles. This constitutes a circuit as shown in FIG.

There is also a model such as Jitsuko Sho 53-8302. This is similar to the plan view shown in FIG. 6 and uses a pattern symmetrical on the front and back. That is, as shown in the plan view of this surface side shown in FIG. 7, there is basically a coil 2'on the surface of the insulating film 1 '.
Capacitors 3a 'and 4a' are provided at both ends of. Then, there is a coil and a capacitor having the same shape as the pattern on the front surface side as in the plan view (that is, the bottom view) on the back surface side shown in FIG. That is, basically, the same coil 2 ″ as the above coil 2 ′ is provided on the back surface of the insulating film 1 ′.
There is the above capacitor 3a ′ on both ends of this coil 2 ″,
The same capacitors 3a "and 4a" as 4a 'are provided. That is, an independent and separate capacitor is an essential requirement. As a result, a resonance circuit as shown in FIG. 9 is formed.

Another feature of the present invention, which is greatly different from that of the present invention, is that the coil has a spiral shape in a "gradually slanted state" toward the center, as is apparent from Figs. 7 and 8. is doing. Therefore, the front side coil and the back side coil do not overlap as much as possible. Therefore, most of the two coils play only the role of the coil, and the independent capacitor as described above is required separately from the coil.

[Problems to be Solved by the Invention] In the conventional resonance circuit, the capacitor is required separately from the coil as described above, and therefore the size of the capacitor must be increased by the area of the capacitor. I didn't get it. If capacitors are requested separately, the performance will deteriorate in a resonance circuit of the same area. It is possible to wind the coil with a correspondingly large circumference, unless the capacitor is required separately. The reason is that the performance of the coil increases with a larger circumference. Furthermore, if a capacitor is provided at the center of the coil, the performance of the coil will be degraded.

Furthermore, winding the coil on only one side inevitably results in a smaller inner circumference of the coil with the same size, which leads to a decrease in sensitivity.

[Means for Solving the Problems] In view of the above problems, the united LC resonance circuit according to the present invention has two reversely wound planar coils arranged in parallel when viewed from one side, and the sensitivity of the coils is more than double. I raised it to. Furthermore, most of these two coils overlap each other, and these two coils are constructed so as to serve as capacitors as they are.

The specific configuration of the combined LC resonance circuit according to the present invention will be described below.

First, there is the first resonant circuit half. The first resonance circuit half end is a coil wound in a spiral shape on the same plane and constitutes one pole of the capacitor. next,
There is a second resonant circuit half end. This resonant circuit half is
Similarly to the resonance circuit half end, the coil is a coil wound in a spiral shape on the same plane and forms the other pole of the capacitor. Then, this has the same shape as the first resonance circuit half end and is placed in parallel with and flipped over the first resonance circuit half end. Further, the above-mentioned spiral shape has a shape in which most of the first resonance circuit half end and the second resonance circuit half end overlap each other when seen through from one surface side thereof.

Therefore, the connection from one loop of a coil (whether it is a square or a square) to its adjacent loop is a step. Of course, this step is preferably 90 degrees, such as the portion surrounded by the dotted line in FIG. 16, but is not limited to this. That is, it may be 45 degrees or 20 degrees, such as the portion surrounded by the dotted line in FIGS. 13 and 14.

The united LC resonance circuit according to the present invention has the following effects due to the above-described configuration.

(Operation) That is, both the first resonance circuit half end and the second resonance circuit half end are coils that are spirally wound on the same plane, and since they are on the same axis in parallel, induction action is also added to double. Perform the above functions. Furthermore. The two coils spirally wound on the same plane simultaneously form the respective poles of the capacitor. Therefore, the first resonance circuit half end and the second resonance circuit half end form an electric resonance circuit as shown in the circuit diagram of FIG.

[Embodiment] A combined LC resonance circuit according to the present invention will be described below with reference to the accompanying drawings showing an embodiment thereof.

FIG. 1 is a plan view of an embodiment of a united LC resonance circuit according to the present invention.

FIG. 10 shows a reduced surface view of that of FIG.

FIG. 11 shows a reduced back view of that of FIG.

FIG. 12 shows a circuit diagram for the explanation.

First, there is an insulating film 1 made of polyethylene. The insulating film 1 is not limited to polyethylene.
However, any material with high dielectric properties or where aluminum easily adheres may be used.

Next, a first resonance circuit half end 10 is provided on the polyethylene insulating film 1. The first resonance circuit half-end 10 is composed of a coil 11 made of an aluminum film spirally wound on the same plane. The coil 11 simultaneously forms one pole 12 of the capacitor 30.

Further, the second resonance circuit half end 20 is provided on the back surface side of the polyethylene insulating film 1. Similar to the first resonance circuit half-end 10, the resonance circuit half-end 20 is composed of a coil 21 made of an aluminum film spirally wound on the same plane. And this coil 21
Similar to coil 11 above, at the same time it itself forms the other pole 22 of capacitor 30.

Therefore, the first resonance circuit half end 10 and the second resonance circuit half end 20 have the same shape. The second resonance circuit half-end 20 is placed in parallel with the first resonance circuit half-end 10 and turned upside down. Further, among the spirals mentioned above, the spiral used here is such that, when seen through from one surface side, most of the first resonant circuit half end and the second resonant circuit half end overlap each other. It is a shape.

Incidentally, the resonant circuit half ends 10 and 20 may be provided on the same insulating film, or may be provided on separate insulating films and then laminated. .

Further, the insulating film 1 is not limited to polyethylene and may be any one having a high dielectric property. Since the resonant circuit halves 10 and 20 are usually made of aluminum, it is preferable that the insulating film 1 has an aluminum film easily attached thereto.

Furthermore, both of the resonant circuit halves 10 and 20 are
The film is not limited to an aluminum film, and one of the films may be an aluminum film and the other may be another film.

Similarly, it may be formed by printing with a conductive ink or hot stamping with a conductive substance.

The shape may be circular as shown in FIGS. 13 and 14, or may be rectangular as shown in FIGS. 15 and 16. Further, the transition from the first wheel to the second wheel may be stepped as shown in FIGS. 13 and 15 or may be steep as shown in FIG. It may be (see the part inside the dotted line).

Finally, as shown by the symbol A in FIG. 15, assuming that the resonance circuit halves 10 and 20 are at the same location and one or more locations thereof are widened, the capacitor can be simply removed by cutting this section. It is possible to adjust the capacitance and to manufacture various resonant frequencies.

Although the first resonance circuit half-end 10 and the resonance circuit half-end 20 are described as having the same shape in the text, one of them has to be thicker in order to absorb the difference due to the deviation of its position in manufacturing. Therefore, here, "the same shape means a shape in the same range required in terms of function".

(Advantages of the Invention) Since the planar resonant circuit tag according to the present invention is configured as described above, it is possible to increase the sensitivity of the coil.

That is, since the first resonance circuit half end and the second resonance circuit half end are both spirally wound coils on the same plane, the coil has a margin to be doubled in the same area. It could contribute to the increase in the width of the coil wire. Moreover, the sensitivity of these two coils increased more than twice by induction.

Further, since it is not necessary to provide a metal piece for the capacitor on the inner circumference of the coil, it is not necessary to reduce the sensitivity of this coil. In addition, since it is not necessary to take space for a capacitor on the outer circumference of this coil, it is possible to further increase the sensitivity of this coil. Cover, coil,
This is because the sensitivity increases as the diameter increases.

In addition, the effects of each of the embodiments described in the text were sufficiently enhanced.

[Brief description of drawings]

FIG. 1 is a plan view of an embodiment of the combined LC resonance circuit of the present invention. FIG. 2 is a plan view of an embodiment of a conventional tag-shaped resonance circuit. FIG. 3 shows a plan view of the front side of that of FIG. FIG. 4 shows a plan view of the thing of FIG. 2 seen from the back side. FIG. 5 shows a circuit diagram of that of FIG. FIG. 6 is a plan view of another embodiment of a conventional tag-shaped resonance circuit. FIG. 7 shows a plan view of the front side of that of FIG. FIG. 8 shows a plan view of the thing of FIG. 6 seen from the back surface side. FIG. 9 shows a circuit diagram of that of FIG. FIG. 10 shows a reduced surface view of that of FIG. FIG. 11 shows a reduced back view of that of FIG. FIG. 12 shows a circuit diagram for the explanation. 13 to 16 are surface views of another embodiment of the united LC resonance circuit of the present invention. 1 ... Insulating film, 2 ... Coil 3 ... Capacitor, 10,20 ... Half end of resonant circuit 11,21 ... Coil, 12,22 ... Capacitor

Claims (10)

[Claims] 1. A coil wound in the same plane in a spiral shape, and a first resonance circuit half end forming one pole of a capacitor, and a coil wound in the same plane in a spiral shape. And a second resonance circuit half-end which forms the other pole of the capacitor and has the same shape as the first resonance circuit half-end and which is placed in parallel and inside out on the first resonance circuit half-end. And the spiral shape is a shape in which most of the first resonant circuit half end and the second resonant circuit half end overlap each other when seen through from one surface side thereof. . 2. The united LC resonance circuit according to claim 1, wherein each resonance circuit half end is provided on the same insulating film. 3. The united LC resonant circuit according to claim 1, wherein each resonant circuit half end is provided on a separate insulating film. 4. The united LC resonant circuit according to claim 2 or 3, wherein the insulating film is made of a material having a high dielectric constant. 5. The united LC resonance circuit according to claim 4, wherein the insulating film is made of polyethylene. 6. The united LC resonance circuit according to claim 2, wherein the insulating film is made of a material to which an aluminum foil easily adheres. 7. The united LC resonance circuit according to claim 1, wherein one or both of the resonance circuit halves is made of an aluminum foil. 8. The united LC resonance circuit according to claim 1, wherein one or both ends of the resonance circuit are formed by printing with a conductive ink. 9. The united LC resonance circuit according to claim 1, wherein one or both of the resonance circuit halves is formed by hot stamping with a conductive material. 10. The united LC resonance circuit according to claim 1, wherein each of the resonance circuit half ends is at the same location and one or more locations thereof are spread.