JPS60158702A - Antenna for vehicle - Google Patents

Abstract

PURPOSE:To attain transmission/reception with high sensitivity by attaching an antenna to a door mirror and therefore avoiding the wear and breakage of the antenna with reduction of the effect of a metallic vehicle body. CONSTITUTION:A loop antenna 24 is stuck with a synthetic resin adhesive, etc. to a frame 25 formed along the fringe of a mirror 22 of a door mirror 20. The attachment screw holes are formed at the inner corner parts of the frame 25, and screw bosses corresponding to said screw holes are provided on the rear side of the mirror 22. Then the antenna 24 is fixed with screws to the rear side of the mirror 22 together with the frame 25. Thus the antenna 24 receives no effect of a metallic vehicle body and can transmit and receive radio signals with high sensitivity. Furthermore the antenna 24 can avoid the wear and breakage due to contact with vehicle body since it is hidden by a door mirror shell 21 and the mirror 22.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a vehicle antenna suitable for transmitting and receiving radio signals between an internal device and an external device of a vehicle.

(Background of the Invention) The applicant of the present application previously proposed an RM radio wave type key system in Japanese Patent Application No. 132118/1983 (unpublished). This radio key system is applied to vehicle door locks, for example, when the driver holds a transmitter instead of the key, and only when the person in possession of the transmitter operates the switch installed on the door. The door lock is configured to be unlocked or locked.

FIG. m1 is a block diagram showing a schematic configuration of the radio wave type key system (hereinafter referred to as a vehicle locking control device). In the figure, the transmitter 111 is housed in a card-type case, and this card-type transmitter vA1 is carried by the driver in place of the mechanical key of the vehicle 18.

On the other hand, a control device 2 is mounted on the vehicle 18 side,
Furthermore, a loop antenna 10 is provided on the window, and a switch is provided near the door handle on the driver's side door.

The card type transmitter 1 is always powered on,
It is now in a state where it can receive a request signal transmitted from the control device 2 on the vehicle body side.

When the driver carrying this card type transmitter 1 manually operates the switch 12 to unlock the door, the request signal generating circuit 11 in the control device 2 shown in FIG. 1 is activated. , a request signal is transmitted from the loop antenna 10 for a certain period of time. This loop antenna 1
The request signal transmitted from 0 is received by the loop antenna 3 of the card type transmitter 41!11 by electromagnetic induction. Then, on the card type transmitter 1 side, the request signal detection circuit 7 detects that the request signal is transmitted from the control device 2 on the vehicle 18 side, and activates the code signal generation circuit 8.

When the code signal generation circuit 8 is activated, it outputs a code signal specific to the vehicle 18 (a different code is set for each vehicle) that has been stored in the code storage circuit 9 in advance. and,
In the modulation circuit 5, the carrier signal supplied from the carrier oscillation circuit 6 is modulated by the code signal, and the output circuit 4. Transmit via loop antenna 3.

Then, on the vehicle side, the unique code signal transmitted from the card type transmitter 1 is received by the loop antenna 10, and the received unique code signal is sent to the code matching circuit 14 via the receiving/demodulating circuit 13. supplied to

The code matching circuit 14 determines whether or not the vehicle-specific code signal registered in advance in the code storage circuit 15 matches the received code signal. The actuator drive circuit 16 is driven only in certain cases.

Then, when the actuator drive circuit 16 is driven,
The actuator 17, which unlocks and locks the door lock, is driven to unlock the door.

In this way, the door lock is unlocked and locked only when the code signal on the card type transmitter 1 side matches the code signal registered in the control circuit 2 on the vehicle side. Even if a person who does not have the type transmission t11 attempts to unlock the door, the door lock will not be unlocked. Further, even if a person carrying a card type transmitter 1 with a different code signal attempts to unlock the door, the door lock will not be unlocked in the same way. As a result, the card-type transmitter 1 has the same security performance as a conventional mechanical key.

Furthermore, since the card-type transmitter 1 can be used while being stored in a pocket or bag, it eliminates the need to take out the key every time the lock is unlocked or locked, unlike conventional mechanical keys. becomes.

The actuator 17 is configured to reverse the door lock state each time the actuator is driven, and if the door lock is locked before driving, it will unlock the door, and if the door lock is unlocked before driving. If so, perform the locking operation.

By the way, regarding the above-mentioned vehicle locking control device,
As the inventors of the present invention continued their research, they found that it was possible to provide a narrow opening with even better performance by paying attention to the following points during development.

That is, among the antennas used in the above-mentioned vehicle lock control device, the loop antenna attached to the vehicle body needs to be installed as far away from the vehicle body as possible because the vehicle body is made of metal.

Furthermore, the driver possesses the card-type transmission 111,
When operating the vehicle lock control device, it must be located near the driver's door, so the loop antenna on the vehicle body side must be installed near the driver's door.

Considering the above, in order to satisfy these requirements, one idea was to form a loop antenna with a printed pattern on the door window of the driver's door as described above, but this Since there is a risk of abrasion occurring as the door window is raised and lowered, there was a need to develop a more optimal antenna, which led to the invention of the present application.

(Object of the Invention) An object of the present invention is to provide a vehicle antenna that is not affected by a metal vehicle body, has less deterioration, and has good sensitivity.

(Structure of the Invention) In order to achieve the above object, the present invention is characterized in that an antenna is attached to the door mirror.

(Explanation of Examples) FIG. 3 is a sectional view showing the configuration of an embodiment of the present invention.

As shown in the figure, inside the door mirror outer shell 21, the outer shell 21
A mirror 22 is disposed in the opening, and a drive unit 23 equipped with a motor for rotating the mirror 22 in vertical and horizontal directions is provided inside the outer shell 1.

A loop antenna 24 is attached to the back surface of the mirror 22 via a frame 25 made of synthetic resin.

As is well known, the door mirror 20 is provided so as to protrude from the surface of the driver's door and the passenger's door to both sides of the vehicle body, as shown in FIG. It exists in a certain position.

As shown in FIG. 5, the loop antenna 24 is attached to a frame 26 formed in a frame shape along the outer periphery of the mirror 22 with a synthetic resin adhesive or the like, and is attached to an inner corner of the frame 25. A mounting screw hole 26 is provided in the holder.

Correspondingly, a screw boss 27 is provided on the back surface of the mirror 22, and the loop antenna 24 is fixed together with the frame 25 by screwing to the back surface of the mirror 22.

As described above, the vehicle antenna of this embodiment is installed inside the door mirror 20 and on the back side of the mirror 22, so that it can transmit and receive wireless signals with high sensitivity without being affected by the metal vehicle body. I can do it. Further, since it is hidden by the door mirror outer shell 21 and the mirror 22, wear and damage due to contact can be avoided.

Next, it will be clearly explained below whether or not good sensitivity can actually be obtained with the vehicle antenna of the above embodiment.

First, as mentioned above, the loop antenna 24 is attached to the back of the mirror.
When a mirror 220 reflective film is installed, a magnetic material such as chromium or nickel is used in the mirror 220 reflective film, so electromagnetic waves may be attenuated when they pass through this mirror reflective film. There is a question as to whether this is the case, but experiments have shown that this is because the mirror reflection film is extremely thin (about 5,000 layers), so there is no significant difference in transmittance from that of non-magnetic materials.

Note that since the door mirror outer shell 21 is usually made of synthetic resin, this also does not affect the sensitivity.

Furthermore, in order to make it clearer that it is optimal to attach the loop antenna 24 to the back surface of the mirror 22, data obtained through experiments by the inventors of the present application are shown below.

The comparison target used in the experiment was poly-like at A in Figure 3.
A case where a loop antenna is attached to the inner bottom of the door mirror outer shell 21 and a case where a loop antenna is attached to the outer periphery of the door mirror outer shell 21 as shown in FIG. I looked at the transmission output and detectable distance.

Note that the above transmission output is 1°51 from the loop antenna.
The electric field strength (dBμV/m ) and the detectable distance at the point I are determined by the card-type transmitter 1 shown in FIG. (which has been found to be necessary) indicates the maximum distance that can be obtained.

The experimental data obtained under these conditions are shown in Table 1 below.
Shown below.

(Table 1) Transmission output detectable distance This example 127 1°35 position 123 1.15 B position 128.5 1.41 (dBμV/m) (m) Note that the above transmission output detection position is The reason for setting the point 1.5 m from the antenna is that when the vehicle antenna of this embodiment device is used in the vehicle lock control device described above, the signal is transmitted to a distant card type transmitter. In order to avoid this, the communication range is set to a radius of 1.511
This is intended to be limited to a certain extent.

Further, as shown in FIG. 6, the loop antenna is composed of a 10-turn antenna wire 31 with a capacitor 30 interposed therebetween to form a closed loop, and a 1-turn antenna wire 32 wound integrally with the antenna wire 31. A one-turn antenna wire 32 is connected to the request signal generation circuit 11 and reception demodulation circuit 13 in the vehicle body control device 2 shown in FIG. The output shown in Table 1 above indicates the electric field intensity obtained when driving with a voltage of 12V from the vehicle battery.

In addition, the transmission output when setting the above detectable distance is 13
The reason for setting 0 dBμV/II is that when the vehicle antenna of this embodiment is similarly used in the vehicle lock control device,
This is because it is necessary to input this level of transmission output from the viewpoint of the battery life of the card type transmitter. This is because if the transmission output is 1306 BμV/I or less, it becomes necessary to increase the number of amplifiers on the card type transmitter side in order to increase the sensitivity, which shortens the life of the battery.

From the experimental results shown in Table 1 above, it can be seen that, first of all, when the loop antenna is provided at the position A in FIG. 3, both the transmission output and the detectable distance are low.

Furthermore, if the loop antenna is installed at position B in Figure 3, the transmission output and detectable distance will be large; however,
In this case, there is a risk that the loop antenna may come into contact with external objects, which may cause wear and tear, and it is necessary to arrange the layout so as not to damage the appearance.

In addition, in order to improve the appearance, the door mirror outer shell 21
It is also conceivable to embed a loop antenna along the outer periphery of the antenna by insert molding, but this type of insert molding increases the manufacturing cost, and since the insert is made of a different material, it is difficult to There is also a possibility that sink marks may occur, which may lead to deterioration of the appearance.

Therefore, in this embodiment, it is optimal to attach the loop antenna to the back surface of the mirror.

(Effects of the Invention) As described above in detail, the vehicle antenna of the present invention is less affected by the metal vehicle body, can perform highly sensitive transmission and reception, and can prevent wear and damage.

In addition, it does not affect the appearance and! The manufacturing cost can also be provided at low cost.

Further, due to such effects, it is possible to provide an optimal antenna for, for example, the above-mentioned vehicle locking control device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a schematic configuration of the vehicle locking control device according to the prior application, FIG. 2 is a diagram showing the appearance of the device and how it is mounted on a vehicle, and FIG. 3 is a diagram showing the vehicle antenna of the present invention. FIG. 4 is a cross-sectional view showing the configuration of one embodiment, FIG. 4 is a diagram showing the mounting state of the door mirror, FIG. 5 is an exploded perspective view showing the structure of the attachment of the loop antenna of the same embodiment, and FIG. This is the equivalent circuit of a loop antenna. 20...Door mirror 21...Door mirror outer shell 22...Mirror 24...Loop antenna patent applicant Nissan Motor Co., Ltd.

Claims (3)

[Claims] (1) An antenna on the vehicle body side used for transmitting and receiving wireless signals between an internal device and an external device of the vehicle; characterized in that the antenna is attached to a door mirror. Vehicle antenna. (2) The vehicle antenna according to claim 1, wherein the antenna is attached to the rear surface of the door mirror. (3) The vehicle antenna according to claim 1, wherein the antenna is a looped antenna attached to the outermost side of the rear surface of the door mirror.