JPH0797880A - Receiver and antenna built in receiver - Google Patents

Abstract

PURPOSE:To suppress the change of the tuning point and the change through the lapse of years and facilitate the tuning work of a receiver in the production process. CONSTITUTION:An antenna 101 built in a receiver is constituted of a cylindrical bobbin 102 formed from the material having the proper dielectric constant, and a dipole type helical antenna 103 wound on the bobbin 102. A flange shaped antenna fixing member 104 is installed at both the end parts of the bobbin 102, and a cut part 104a is formed at the antenna fixing part 104. At the end part of a printed circuitboard 105 having the inside circuit of the receiver formed, the cut part 104a is fitted, and the antenna 101 built in the receiver is fixed for the printed circuitboard 105.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver and an antenna with a built-in receiver, and more particularly to an on-vehicle receiver for a radio wave key system and an antenna built in the on-vehicle receiver.

[0002]

2. Description of the Related Art In recent years, devices called "radio wave key systems" have been widely used in automobiles. In the radio wave key system, radio waves are emitted from the transmitter built into the ignition key, and the radio waves are received by the in-vehicle receiver, which enables control such as door lock and engine start even from a place away from the automobile. .

In this radio wave key system, initially,
The method of attaching the receiving antenna outside the vehicle was common. However, in recent years, it has been considered that a reception antenna is built into a vehicle-mounted receiver to eliminate extra protrusions outside the vehicle and improve aesthetics.

[0004]

However, when the receiving antenna is built in the receiver, the mounting location of the receiver in the vehicle determines the working distance (directivity) of the radio wave key system. That is, since the automobile is a metal box having a complicated shape, the electric field inside the automobile greatly varies depending on the place. Therefore, for example, when the receiver is installed under the seat and when it is installed in the trunk room, the directivity of the receiver is different and the working distance (directivity) of the radio wave key system is changed.

However, the mounting place given to the receiver is
It is a narrow place such as under the seat, in the luggage compartment, or behind the instrument panel. Therefore, a sufficient space cannot be provided around the receiver built-in antenna, and the generated electric field is often weak. Further, when the receiver is mounted under the seat, the seat is slid in the front-rear direction, so that the electric field generated greatly changes depending on the sliding position of the seat.

Therefore, when the receiving antenna is built into the receiver, there is a demand for a receiver capable of obtaining optimum receiving characteristics depending on the place where it is mounted. by the way,
In the radio key system, the UHF band is generally used. U
When the receiving antenna is built into the HF band receiver, a small and highly efficient helical antenna is usually used as the receiving antenna. Further, in order to further increase the gain, the helical antenna often has an air core structure.

In the air-core structure helical antenna, since the permittivity of air is extremely low, the antenna loss is also extremely low and the efficiency can be improved. On the other hand, the resonance characteristics of the antenna become extremely sharp, the tuning point tends to fluctuate, and secular change easily occurs. In addition, since the resonance characteristic of the antenna is sharp, the tuning work of the receiver in the production process becomes critical and difficult. Further, the variation of the tuning point of the antenna is affected by the electric field at the mounting location of the receiver inside the vehicle. Therefore, particularly when the receiver is mounted under the seat, the tuning point of the antenna also greatly varies due to the electric field that changes depending on the sliding position of the seat, as described above.

Further, since the air-core structure of the helical antenna has low mechanical strength, some fixing means must be provided.
This will promote the above-mentioned problems of fluctuation of the tuning point and aging.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an antenna built-in type capable of obtaining an optimum reception characteristic according to a mounting place. Is to provide a receiver.

An object of the present invention is to provide an antenna with a built-in receiver, which is unlikely to cause a change in tuning point or secular change, and which can facilitate tuning work of the receiver in the production process. Especially.

[0011]

The gist of the invention according to claim 1 is that the built-in antenna is arranged according to the strength of the generated electric field or the state of the vector.

[0012] The gist of the invention according to claim 2 is that it comprises a bobbin formed of a material having an appropriate permittivity and a helical antenna wound around the bobbin.

[0013]

Therefore, according to the first aspect of the invention, since the built-in antenna is arranged according to the strength of the generated electric field or the state of the vector, the receiving characteristic is optimized depending on the mounting position of the receiver. Can be something.

According to the second aspect of the invention, the resonance characteristic of the antenna can be broadened by using a material having a high dielectric constant for the bobbin. as a result,
Variations in the tuning point and changes over time are less likely to occur, and the tuning work of the receiver in the production process becomes easier.

[0015]

【Example】

(Embodiment embodying the invention described in claim 1) Hereinafter, the receiver with a built-in antenna of the first to third embodiments embodying the invention described in claim 1 will be described with reference to the drawings.

FIGS. 1 to 3 are perspective views of a printed circuit board and a receiver built-in antenna which constitute the receiver with built-in antenna of each embodiment. As shown in FIG. 1, in the first embodiment, the same helical antenna 12 is mounted on the printed circuit board 11.
Two a and 12b are set up.

As shown in FIG. 2, in the second embodiment, the same helical antennas 12x and 12y are provided on the printed circuit board 11.
Is provided. Each helical antenna 12x, 12y
The angles formed by the axes are 90 °, which correspond to the x and y axes.

As shown in FIG. 3, in the third embodiment, the same helical antennas 12x to 12z are mounted on the printed circuit board 11.
Is provided. Each helical antenna 12x-12z
The angles formed by the axes are 90 °, which correspond to the x, y, and z axes.

FIG. 4 shows the circuit configuration of the receiver of each embodiment. A synthetic matching circuit 13 is provided on the printed circuit board 11.
And a receiving circuit 14 is formed. The helical antennas 12 a, 12 b, 12 x to 12 z are mated by the synthetic matching circuit 13 and connected to the receiving circuit 14. Therefore, the respective helical antennas 12a, 12b, 12x to 12z are combined and operate. The synthetic matching circuit 13 is a general impedance matching circuit based on LC.

The following effects can be obtained in each of the embodiments thus configured. (1) Each helical antenna 12a, 12b, 12x-12
By providing a plurality of z's and combining them, the volume of the antenna increases, so that the bandwidth of the antenna can be widened. As a result, it is possible to reduce the influence of the electric field at the mounting location of the receiver on the reception characteristics (that is, the working distance (directivity) of the radio wave key system).

(2) By optimally selecting the first to third embodiments according to the state of the electric field (electric field strength or vector) at the mounting location of the receiver, the optimum receiving characteristics can be obtained according to the mounting location. Obtainable.

For example, as shown in FIG. 5, the electric field distribution under the sheet 21 has a small x-axis component and a small y-axis component and a large z-axis component. This is because an electric field is formed between the vehicle ceiling and the seat frame and chassis. Even under the same sheet 21, the magnitude of the z-axis component of the electric field differs depending on the position. This is because the shapes of the ceiling, seat frame, and chassis of the automobile are complicated. Further, since the seat 21 is slid in the front-rear direction, the electric field generated varies greatly depending on the sliding position of the seat 21.

Under the sheet 21 as described above, the first embodiment shown in FIG. 1 is effective. That is, as shown in FIG. 5, even when the z-axis component of the electric field corresponding to the helical antenna 12a is small, the z-axis component of the electric field corresponding to the helical antenna 12b has a certain magnitude. for that reason,
A sufficient gain can be obtained when the helical antennas 12a and 12b are viewed in total.

The state of the electric field vector may vary greatly depending on the mounting location of the receiver in the vehicle. For example, the helical antenna 12 for the automobile 31
The directivity of y (y axis) is as shown in FIG.
The directivity of the helical antenna 12x (x axis) is shown in FIG. 6 (b).
In case of the above, the second embodiment shown in FIG. 2 is effective. That is, in the second embodiment, the x-axis and y
Since the electric fields in the two axial directions can be received, the combined directivity of the helical antennas 12x and 12y is as shown in FIG. 6C, and a sufficient gain can be obtained in total.

In the third embodiment shown in FIG. 3, in addition to the second embodiment, a helical antenna z corresponding to the z-axis is provided,
Since electric fields in three directions of the x-axis, the y-axis, and the z-axis can be received, more complicated electric field vector states can be dealt with.

Thus, in the second and third embodiments,
By selecting the axial direction of each of the helical antennas 12a, 12b, 12x to 12z according to the electric field vector of the mounting location of the receiver, the reception directivity can be made almost omnidirectional regardless of the mounting location of the receiver. . Therefore, the working distance (directivity) of the radio wave key system is not influenced by the installation location of the receiver in the vehicle.

(Embodiment embodying the invention described in claim 2) Hereinafter, the receiver built-in antennas of the first and second embodiments embodying the invention described in claim 2 will be described with reference to the drawings.

FIG. 7 shows a plan view of the receiver built-in antenna of the first embodiment, and FIG. 8 shows a side view thereof. The receiver built-in antenna 101 of this embodiment includes a cylindrical bobbin 102 formed of a material having an appropriate dielectric constant, and a dipole type helical antenna 103 wound around the bobbin 102. A flange-shaped antenna fixing member 104 is provided at both ends of the bobbin 102, and the antenna fixing member 104 is provided with a notch 104a. Then, the receiver built-in antenna 101 can be fixed to the printed circuit board 105 by fitting the notch 104a into the end of the printed circuit board 105 on which the internal circuit of the receiver is formed. In addition, the end portion 103a of the helical antenna 103 is connected to the printed circuit board 105.
The internal circuit of the receiver and the antenna 101 with a built-in receiver are connected by being inserted into the through hole 105a formed in and soldering the end 103a to the print pattern 105b formed on the back surface of the printed circuit board 105. be able to.

FIG. 9 is a plan view of the receiver built-in antenna of the second embodiment, and FIG. 10 is a side view thereof. The receiver built-in antenna 111 of the present embodiment is composed of a cylindrical bobbin 112 having a bottom surface and a monopole type helical antenna 113 wound around the bobbin 112.
The bobbin 112 is formed of a material having an appropriate dielectric constant, and has a screw hole (not shown) on the bottom surface thereof. Then, the bobbin 112 is arranged on the printed circuit board 115 on which the internal circuit of the receiver is formed.
5. The receiver built-in antenna 111 is fixed to the printed circuit board 115 by inserting a bolt 116 into a screw hole (not shown) provided in FIG. 5 and a screw hole on the bottom surface of the bobbin 112 and fixing it with a nut 117. You can Further, the end portion 113a of the helical antenna 113 is attached to the printed circuit board 1
An internal circuit of the receiver and the receiver are formed by inserting the end portion 113a into a through hole (not shown) formed in 15 and soldering an end portion 113a thereof to a print pattern (not shown) formed on the back surface of the printed circuit board 115. The built-in antenna 111 can be connected. A convex portion 112a is provided on the outer wall of the bobbin 112, and the lead portion 113b following the end portion 113a of the helical antenna 113 has a convex portion 112a.
It is designed to be fixed by a.

In this way, each receiver built-in antenna 10
By using bobbins 102 and 112 made of a material having an appropriate dielectric constant for 1,111,
An appropriate loss can be given to the antenna to broaden the resonance characteristic.

For example, when each bobbin 102, 112 is formed of a synthetic resin material, a desired resonance characteristic can be obtained by appropriately selecting the synthetic resin material. By the way, as a synthetic resin material, polypropylene (2.2
), ABS (2.6), polyacetal (3.7), nylon (4.6), etc. (relative permittivity in parentheses). By the way, the higher the dielectric constant of each bobbin 102, 112, the broader the resonance characteristic of each receiver built-in antenna 101, 111. Therefore, among the above synthetic resin materials, when nylon is used as the material of the bobbins 102 and 112, the resonance characteristics of the receiver built-in antennas 101 and 111 are broadest.

Therefore, each receiver built-in antenna 101, 1
According to No. 11, it becomes difficult to cause a change in the tuning point and a secular change. Also, the tuning work of the receiver in the production process becomes easy. Further, since the variation of the tuning point is small, it is less likely to be affected by the electric field at the mounting position of the receiver in the vehicle.
Therefore, for example, the receiver built-in antennas 101, 11
Even when the receiver incorporating 1 is mounted under the seat, the variation of the tuning point of the antenna due to the sliding position of the seat is reduced.

However, giving a loss to the antenna leads to a reduction in efficiency. However, each helical antenna 10
By increasing the outer shape of 3,113, the antenna volume can be increased and the required gain can be obtained.
There is no practical problem.

In the receiver built-in antenna 101, the bobbin 102 is made of a synthetic resin material so that the antenna fixing member 104 can be formed integrally with the bobbin 102. On the other hand, the built-in receiver antenna 11
Also in No. 1, by forming the bobbin 112 from a synthetic resin material, the bottom surface of the bobbin 112 functioning as an antenna fixing member can be formed integrally with the bobbin 112.

Therefore, it is possible to increase the mechanical strength of the receiver built-in antennas 101 and 111 and securely fix them to the printed circuit boards 105 and 115 without separately providing a fixing means. It is possible to solve the problem of tune point fluctuation and aging.

Further, according to the receiver built-in antenna 101, since the antenna is not arranged on the printed circuit board 105, the size of the printed circuit board 105 can be reduced. The present invention is not limited to the above embodiments, but may be carried out as follows.

1) The composite matching circuit 13 shown in FIG. 4 is omitted, and the print pattern of the input portion of the receiving circuit 14 is provided with the composite matching function of the helical antennas 12a, 12b, 12x to 12z.

2) In the first embodiment shown in FIG. 1, three or more helical antennas are provided. In addition, the first shown in FIG.
The embodiment is used in combination with the second embodiment shown in FIG. 2 or the third embodiment shown in FIG. That is, the x, y axes or x, y, z
Two or more helical antennas are provided on the shaft.

3) In each of the embodiments shown in FIGS.
The angle formed by each of the helical antennas 12a, 12b, 12x to 12z is set to an appropriate angle other than 90 ° in accordance with the electric field vector.

4) In each of the embodiments shown in FIGS.
Each of the helical antennas 12a, 12b, 12x to 12z is replaced with another type of antenna (rod antenna, planar antenna,
It is replaced with an antenna formed by the printed pattern on the printed circuit board 11).

5) A monopole type helical antenna is used in the receiver built-in antenna 101 shown in FIGS. 7 and 8. Further, a dipole type helical antenna is used in the receiver built-in antenna 111 shown in FIGS. 9 and 10.

6) The embodiments shown in FIGS. 1 to 3 and the embodiments shown in FIGS. 7 to 10 are used together. That is, FIGS.
In each of the embodiments shown in, each helical antenna 12a,
12b and 12x to 12z are formed by winding a cylindrical bobbin made of a material having an appropriate dielectric constant.
In this case, each embodiment shown in FIGS. 1 to 3 and FIGS.
It is possible to realize a higher performance receiver by the synergistic effect with each of the embodiments shown in FIG.

[0043]

As described above in detail, according to the first aspect of the present invention, it is possible to provide a receiver with a built-in antenna that can obtain optimum reception characteristics depending on the mounting location.

According to the second aspect of the present invention, there is provided an antenna with a built-in receiver, which is unlikely to cause a change in tuning point or secular change, and which can facilitate tuning work of the receiver in the production process. be able to.

[Brief description of drawings]

FIG. 1 is a perspective view of a printed circuit board and a receiver built-in antenna that constitute a receiver with a built-in antenna according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a printed circuit board and an antenna with a built-in receiver which constitute a receiver with a built-in antenna of a second embodiment embodying the invention described in claim 1.

FIG. 3 is a perspective view of a printed circuit board and an antenna with a built-in receiver, which constitute a receiver with a built-in antenna, according to a third embodiment of the present invention.

FIG. 4 is a block circuit diagram showing a circuit configuration of a receiver of each embodiment embodying the invention described in claim 1.

FIG. 5 is an explanatory diagram for explaining the operation of the first embodiment that embodies the invention described in claim 1;

FIG. 6 is a directional diagram for explaining the operation of the second embodiment embodying the invention described in claim 1.

FIG. 7 is a plan view of an antenna with a built-in receiver according to a first embodiment of the invention as set forth in claim 2;

FIG. 8 is a side view of an antenna with a built-in receiver according to a first embodiment of the invention as set forth in claim 2;

FIG. 9 is a plan view of a receiver built-in antenna of a second embodiment embodying the invention described in claim 2;

FIG. 10 is a side view of an antenna with a built-in receiver according to a second embodiment of the invention as set forth in claim 2;

[Explanation of symbols]

12a, 12b, 12x to 12z ... Helical antennas as built-in antennas, 102, 112 ... Bobbins, 10
3,113 ... Helical antenna

Front page continued (72) Inventor Yoshio Nakano No. 1 Noda, Toyoda, Oguchi-cho, Niwa-gun, Aichi Prefecture Tokai Rika Electric Co., Ltd.

Claims (2)

[Claims] 1. A built-in antenna (12a, 12b, 12x)
.About.12z) are arranged according to the strength of the generated electric field or the state of the vector. 2. A bobbin (102, 112) formed of a material having an appropriate dielectric constant, and the bobbin (10).
2, 112), and a helical antenna (103, 113) formed by being wound around the receiver.