CN102956991A - Antenna - Google Patents

Abstract

The antenna (A) of the present invention includes: a loop antenna element unit (1) composed of conductors (11a to 11d) extending in a loop; and a relay substrate (2) connected to the end of the loop antenna element unit (1). The relay substrate (2) includes: an insulating plate (20); external connection pads (21, 22); element connection pads (23a-23h); and capacitor patterns (24, 25). The external connection pads (21, 22) are arranged on the surface of the insulating plate (20), and are connected with the conductors of the transceiver equipment. The element connection pads (23a-23h) are provided on either the front surface or the back surface of the insulating plate (20), and are connected to the end of the loop antenna element part (1). The capacitor pattern (24, 25) is provided on the back surface of the insulating plate (20), in a region facing the external connection pads (21, 22) across the insulating plate (20), and is connected to the element connection pads (23a, 23h ) are electrically connected to form capacitors between the capacitor patterns (24, 25) and external connection pads (21, 22). Accordingly, an antenna having a filter unit with a reduced area and a reduced number of parts can be provided.

Description

antenna

technical field

The present invention relates to antennas.

Background technique

A loop antenna (loop antenna) is used for transmitting and receiving RFID (Radio Frequency IDentification, radio frequency identification) for short-range wireless communication. For example, Patent Document 1 discloses an RFID antenna in which a plurality of individual antennas connected in series form multiple loops by connecting a plurality of individual antennas to a connection portion provided in a housing.

Such an RFID antenna may be equipped with a signal filter in order to reduce noise reaching wireless communication other than RFID, or to reduce coupling with a wireless communication system other than RFID.

For example, Patent Document 2 discloses a configuration in which conductive patterns forming capacitors facing each other and a filter section composed of planar coil patterns are provided on a flexible film including a dielectric resonator device.

Patent Document 1: Japanese Patent Laid-Open No. 2009-60519

Patent Document 2: Japanese Unexamined Patent Application Publication No. H10-242706.

Contents of the invention

However, in this dielectric resonator device, since a pattern dedicated to capacitors is arranged, the area occupied by the filter portion on the flexible film is large. In addition, since an L-shaped connection portion for connecting to a bulky resonator is required, a flexible film is required in addition to the hard substrate serving as the base of the dielectric resonator device. Therefore, the number of parts will increase.

An object of the present invention is to solve the above-mentioned problems and provide an antenna having a reduced-area filter unit with a reduced number of components.

The antenna of the present invention that achieves the above object is characterized in that it has:

a loop antenna element portion composed of a conductor extending in a loop; and

a relay substrate for relaying signals between the loop antenna element unit and the transceiver, and connected to an end of the loop antenna element unit,

The above relay substrate has:

Insulation board;

An external connection pad (pad), which is arranged on the surface of the above-mentioned insulating board and connected with the conductor of the above-mentioned transceiver device;

an element connection pad provided on either one of the front surface and the back surface of the insulating plate, and connected to an end of the element portion of the loop antenna;

The capacitor pattern is provided on the back surface of the insulating plate in a region facing the external connection pad with the insulating plate in between, and is electrically connected to the element connection pad, and a capacitor is formed between the capacitor pattern and the external connection pad. ;as well as

inductor components.

In the antenna of the present invention, a capacitor is directly formed on a relay substrate that relays signals between the loop antenna element unit and the transceiver. In addition, one of the pair of electrodes forming the capacitor also serves as an external connection pad. Therefore, the number of components of the antenna is reduced, and the area of the substrate is reduced.

Here, in the antenna of the present invention described above, it is preferable that the inductor element is connected to the external connection pad and the capacitor pattern on the front and back surfaces of the insulating plate, respectively, and in a region facing each other across the insulating plates on the front and back surfaces. The front ends extending in a spiral shape are respectively extended in a spiral shape, and the respective front ends extending in a spiral shape are connected to each other through the insulating plate.

Since the inductor elements are arranged using both of the regions facing each other across the insulating plate, they can be arranged in a small area. Therefore, the area of the substrate is further reduced.

As described above, according to the present invention, an antenna having a filter unit with a reduced number of parts and a reduced area is realized.

Description of drawings

FIG. 1 is an external view of an RFID antenna as an embodiment of the present invention.

FIG. 2 is an external view showing the interposer board shown in FIG. 1 . Part (A) of FIG. 2 is the front surface, and part (B) is the back surface.

Fig. 3 is a circuit diagram showing an equivalent circuit of the RFID antenna shown in Figs. 1 and 2 .

Explanation of reference signs

A: RFID antenna; 1: loop antenna element part; 11a, 11b, 11c, 11d: wire; 2: relay substrate; 20: insulating board; 21, 22: external connection pad; 23a~23h: component connection pad; 24 , 25: capacitor pattern; 26a, 27a: surface inductor pattern; 26b, 27b: back inductor pattern.

Detailed ways

Embodiments of the present invention will be described with reference to the following drawings.

FIG. 1 is an external view of an RFID antenna as an embodiment of the present invention.

The RFID antenna A shown in FIG. 1 is a device for wireless communication in RFID. The RFID antenna A is connected to and operated by a not-shown transmission and reception device.

The RFID antenna A includes a loop antenna element unit 1 and an interposer substrate 2 .

The loop antenna element unit 1 is composed of a plurality of wires 11a to 11d extending in a loop. More specifically, the loop antenna element unit 1 is a multi-core cable C that covers and bundles four individual electric wires 11a to 11d into one. Both ends of the four wires 11 a to 11 d included in the multi-core cable C are connected to the relay board 2 . By using a multi-core cable C having four electric wires 11a to 11d, only by cutting the cable C to a predetermined length and removing the covers at both ends, antenna elements having the same length and surrounding the same area multiple times can be produced inexpensively.

Both ends of each of the four wires 11 a to 11 d are connected to the relay substrate 2 . In addition, two external connection pads 21 and 22 are provided on the interposer substrate 2 . A not-shown transceiving device is connected to external connection pads 21 , 22 .

FIG. 2 is an external view showing the interposer board shown in FIG. 1 . Part (A) of FIG. 2 shows the surface of the relay substrate 2 shown in FIG. 1 ; and part (B) shows the rear surface seen from the side opposite to the part (A).

Interconnect substrate 2 shown in FIG. 2 has an insulating plate 20 and conductor patterns provided on the front and back surfaces (front and back) of insulating plate 20 . The insulating plate 20 is a plate made of an insulating material (dielectric). However, a film made of an insulating material can also be used for the insulating plate 20 . In addition, the conductive pattern is made of a metal material.

On the surface of the insulating board 20 shown in part (A) of FIG. 2 , in addition to the external connection pads 21 and 22 described above, six element connection pads 23 a to 23 h and two surface inductor patterns 26 a are provided. , 27a. In addition, two capacitor patterns 24 and 25 and two back surface inductor patterns 26 b and 27 b are provided on the back surface of the insulating plate 20 shown in part (B) of FIG. 2 .

A not-shown transceiver is connected to the external connection pads 21 and 22, and power and signals can be exchanged between the transceiver and the RFID antenna A (see FIG. 1 ). Terminals of a not-shown transmission and reception device are in contact with the external connection pads 21 and 22 . However, the external connection pads 21 and 22 may be connected to the external connection pads 21 and 22 by, for example, solder connection wires extending from the transmitting/receiving device, in addition to the contacts of the terminals. The external connection pads 21 and 22 have at least an area for connecting a contact portion and a wire of a transceiver device.

Both ends of the electric wires 11 a to 11 d constituting the loop antenna element unit 1 (see FIG. 1 ) are connected to the element connection pads 23 a to 23 h with solder. Some of the element connection pads 23a to 23h are connected to each other via conductor patterns as if the four electric wires 11a to 11d are connected in series. Therefore, a four-turn loop antenna can be fabricated only by soldering both ends of the four electric wires 11a to 11d to the element connection pads 23a to 23h. Among the eight element connection pads 23 a to 23 h , two element connection pads 23 a and 23 h arranged at both ends function as terminals of the loop antenna element unit 1 (see FIG. 1 ) constituted by a four-turn loop.

Capacitor patterns 24 and 25 are provided in regions facing external connection pads 21 and 22 , respectively, with insulating plate 20 interposed therebetween. In addition, the capacitor patterns 24 and 25 are connected to the above-mentioned two element connection pads 23a and 23h via conductor patterns and via holes 24h and 25h, respectively.

Among the capacitor patterns 24 and 25 , one capacitor pattern 24 forms a capacitor element between it and the external connection pad 21 with the insulating plate 20 interposed between it and the external connection pad 21 . In addition, another capacitor pattern 25 sandwiches the insulating plate 20 between it and the external connection pad 22 , and forms a capacitor element between it and the external connection pad 22 . The area where the capacitor patterns 24 and 25 overlap the external connection pads 21 and 22 across the insulating plate 20 is set in consideration of the thickness and dielectric constant of the insulating plate 20 so as to obtain a desired capacitance.

In this embodiment, the external connection pads 21 and 22 also serve as electrodes of the capacitor element. Therefore, the total area occupied by the insulating plates 20 of the capacitor element is reduced.

In addition, two inductor elements are formed on the interposer substrate 2 . Here, focusing on the surface inductor pattern 26a, which is one of the two surface inductor patterns 26a, 27a shown in part (A) of FIG. 2, and the two back surface inductors shown in part (B) of FIG. The backside inductor pattern 26b of one of the patterns 26b, 27b. The surface inductor pattern 26a and the rear inductor pattern 26b extend in a spiral shape in the region facing each other with the insulating plate 20 interposed therebetween. With regard to the swirls of the surface inductor pattern 26 a and the swirls of the back inductor pattern 26 b , current flowing throughout both forms a direction that rotates in the same direction. The combination of the surface inductor pattern 26a and the back surface inductor pattern 26b corresponds to an example of the inductor element referred to in the present invention.

The surface inductor pattern 26a and the back surface inductor pattern 26b respectively extend in a spiral shape and each have inductance. In the present embodiment, since the surface inductor pattern 26a and the rear inductor pattern 26b respectively extend in a spiral shape in the region facing each other across the insulating plate 20, the distance between the surface inductor pattern 26a and the rear inductor pattern 26b Mutual inductance is further increased. Therefore, the total arrangement area for obtaining the required inductance is reduced compared to, for example, a case where two inductor patterns are arranged in parallel on the same surface or a case where they are formed in a single spiral shape. This is also the same for the other surface inductor pattern 27a and the back surface inductor pattern 27b. The combination of these another surface inductor pattern 27a and the back surface inductor pattern 27b also corresponds to an example of the inductor element mentioned in this invention.

In this way, capacitor elements and inductor elements are formed on the interposer substrate 2 . With the formed capacitor element and inductor element, a filter circuit is formed.

Fig. 3 is a circuit diagram showing an equivalent circuit of the RFID antenna shown in Figs. 1 and 2 . Each element in the circuit diagram is indicated by a symbol corresponding to the element shown in FIGS. 1 and 2 .

Between the external connection pad 21 and the loop antenna element part 1, a capacitor element (21, 22) composed of the external connection pad 21 and the capacitor pattern 24, and a capacitor element (21, 22) composed of the surface inductor pattern 26a and the back surface inductor pattern 26b are connected in parallel. inductor elements (26a, 26b). In addition, between the other external connection pad 22 and the loop antenna element part 1, the capacitor element (25, 22) composed of the external connection pad 22 and the capacitor pattern 25, and the capacitor element (25, 22) composed of the surface inductor pattern 27a and the back surface inductor are connected in parallel. Inductor elements (27a, 27b) constituted by an inductor pattern 27b.

These capacitor elements ( 21 , 24 ), ( 25 , 22 ), inductor elements ( 26 a , 26 b ), ( 27 a , 27 b ), and the inductance of the loop antenna element unit 1 constitute a band elimination filter. This filter can radiate signals in the RFID communication frequency band from the RFID antenna A, reduce the influence of noise on other wireless communication functions of electronic equipment equipped with the RFID antenna A, and reduce coupling with other wireless communication systems.

In addition, in the said embodiment, the RFID antenna A was shown as the example of the antenna of this invention. However, the present invention is not limited to an RFID antenna, and may be a communication antenna for other applications and frequency bands.

In addition, the capacitor element and the inductor element in the above-described embodiments constitute a band rejection filter. However, the present invention is not limited thereto, and may be a high-pass filter, a low-pass filter, or a band-pass filter.

In addition, in the interposer substrate 2 in the above-described embodiment, two capacitor elements and two inductor elements are respectively formed. However, the present invention is not limited thereto, and one or more elements may be formed. In addition, component connection pads can also be provided on the back side of the insulating board. In addition, the number of turns of the loop in the loop antenna element unit 1 , that is, the number of electric wires may be other than four.

In addition, in the above-mentioned embodiment, the example in which the element connection pads 23a-23h are arrange|positioned on the surface of the insulating board 20 similarly to the external connection pads 21 and 22 was shown. However, the element connection pads of the present invention may also be arranged on, for example, the back surface of an insulating board.

In addition, in the above-mentioned embodiments, an example in which the electric wire is used as the conductor of the loop antenna element portion referred to in the present invention is shown. However, the conductor of the present invention is not limited to an electric wire, and may be, for example, a pattern of a ring formed on a relay substrate.

Claims (2)

1. antenna is characterized in that possessing:

The loop aerial element portion is made of the conductor that extends in the form of a ring; And

Interposer, the signal between the described loop aerial element portion of relaying and the transceiver is connected with the end of described loop aerial element portion,

Described interposer possesses:

Insulation board;

Outside connection gasket, be located at described insulation board the surface, be connected with the conductor of described transceiver;

Element connection gasket, the surface that is located at described insulation board be connected with the back side any, be connected with the end of described loop aerial element portion;

The capacitor pattern, among the back side of described insulation board, be located at clip this insulation board and with the opposed zone of described outside connection gasket, and be electrically connected with described element connection gasket, between described capacitor pattern and described outside connection gasket, form capacitor; And

Inductor element.

2. antenna as claimed in claim 1, it is characterized in that, described inductor element is connected with described outside connection gasket and described capacitor pattern respectively at surface and the back side of described insulation board, be the whirlpool shape in the mutual opposed zone of this insulation board that clips this surface and this back side and extend, each front end that is respectively the extension of whirlpool shape connects this insulation board and interconnects.

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