JPH053508B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a keyless entry device for a vehicle, and more particularly to a keyless entry device for a vehicle that automatically locks and unlocks a door by receiving a code signal using radio waves from a transmitter. It is something.

[Prior Art] In recent years, keyless entry devices for vehicles that automatically lock and unlock doors by receiving a code signal using weak radio waves from a transmitter have become popular in luxury cars instead of door lock devices that use a general key. It is becoming popular mainly in

Such a keyless entry device for a vehicle not only locks or unlocks a door, but also performs various additional functions such as opening/closing a trunk, opening/closing a window, or providing an alarm against theft. This can provide many conveniences to vehicle users.

By the way, as shown in FIG. 20, such a conventional vehicle keyless entry device transmits a code signal using radio waves (60 MHz in the illustrated example) from the transmitting antenna 12 of the transmitter 10 to the vehicle body 14.
A pole antenna 16 for receiving radio broadcast waves provided on the surface receives the signal, and the received signal is input to the distributor 20 via the feeder line 18. This distributor 20 distributes and outputs the received signal to a radio 22 and a kill entry signal receiver 24.

As a result, a sound is output from the speaker 26 of the radio 22, and a control signal 28 for locking and unlocking the door is output from the keyless entry signal receiver 24.

However, in such a conventional vehicle keyless entry device, the reception signal of the radio broadcast wave reception antenna is divided into two and used, so the sensitivity of radio broadcast wave reception is reduced by about 3 dB.

In addition, the antenna for receiving radio broadcast waves is tuned to focus on the radio broadcast wave band, especially the FM band (76-90MHz), which is used by general vehicle keyless entry devices to propagate code signals. Sufficient sensitivity may not be obtained at the radio wave carrier frequency (60MHz).

Furthermore, in areas with strong electric fields, such as near transmitting stations for FM broadcasts or TV broadcasts, there is strong input interference.
There were problems such as the need to take measures such as filtering or trapping on the receiver side of the keyless entry device.

Therefore, it is necessary to install a dedicated antenna for a vehicle keyless entry device that automatically locks the door by receiving a radio code signal from a transmitter, but a pole antenna protruding from the vehicle body cannot receive the signal. Although it exhibits favorable performance in terms of characteristics, it has always had the fate of being treated as a nuisance in terms of body design.

In addition, even in actual use, such pole antennas are susceptible to damage such as bending or bending, and are subject to mischief or theft.
There are various problems such as the generation of unpleasant wind noise when driving at high speeds, and there has been a strong desire to somehow eliminate this problem, and it is extremely impractical to install a new pole antenna. be.

Therefore, in the past, the receiving loop antenna of a keyless entry device for a vehicle is characterized by a molding provided around the outside handle of the door (Utility Model Publication No. 59-44861).

Such a keyless entry device for a vehicle has the advantage of being able to reliably catch radio waves from a transmitter without changing the shape of the vehicle body.

[Problems to be Solved by the Invention] Problems of the Prior Art However, such conventional improved keyless entry devices for vehicles have relatively low sensitivity, and furthermore, due to their directional characteristics, it is difficult to use the transmitting loop antenna for receiving. Extremely close to the loop antenna (about 10cm)
must be brought close.

Therefore, there has been a problem in that the feature of this type of keyless entry device for a vehicle cannot be fully utilized, which is that the door can be automatically locked and unlocked from a certain distance from the vehicle body.

Purpose of the Invention The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide a keyless entry device for a vehicle that does not damage the appearance of the vehicle body and has excellent directional characteristics. .

[Means for Solving the Problems] In order to achieve the above-mentioned object, the vehicle kill entry device according to the present invention is provided with at least two pick-ups for detecting surface current on the vehicle body, The radio wave reception is characterized in that a surface current induced in the vehicle body by the radio waves is detected by the pickup.

[Function] As is clear from the configuration described above, according to the vehicle keyless entry device according to the present invention, radio wave reception is performed by a pick-up that detects surface current induced in the vehicle body, so the pick-up is built in the vehicle body. possible, and does not damage the beauty of the vehicle body.

In addition, the car body is equipped with two or more pick-ups, and their directional characteristics complement each other, so
A substantially omnidirectional vehicle keyless entry device can be obtained.

Furthermore, it becomes possible to provide a pickup dedicated to the vehicle keyless entry device, and by setting the receivable frequency of the pickup to a narrow band, it is possible to reliably eliminate interference waves from broadcast stations, power transmission lines, etc.

[Embodiments] Preferred embodiments of the present invention will be described below based on the drawings.

Setting position of the pick-up Figures 21 to 26 show the process of determining the most efficient pick-up installation position by examining the surface current distribution characteristics of the vehicle body.

FIG. 21 shows that when the radio wave W from the transmitter passes through the car body B made of a metal conductor, a surface current I corresponding to the strength of the electromagnetic wave is induced in each part of the car body. Among these radio waves, the target is radio waves of around 60 MHz, which belong to a relatively high frequency band and are used for transmitting code signals of vehicle keyless entry devices.

The present invention measures the induced current distribution of the vehicle body in such a specific high frequency band, and installs high frequency pickups in areas where the surface current density is high and there is little noise, and it is possible to know the surface current distribution. For this purpose, computer simulation and actual current intensity were measured at each point.

That is, the surface current was measured by using a probe based on the same principle as a pick-up installed on a desired part of the car body, which will be described later, and moving this probe across the entire surface of the car body while changing the direction at each point. .

Figure 22 shows the schematic configuration of a probe P created based on almost the same principle as the high-frequency pickup described later. A loop coil 42 is fixed inside 40. An opening 40 is provided in a part of the case 40.
a, a part of the loop coil 42 is exposed to the outside through this opening 40a, and the exposed portion of the loop coil 42 is brought close to the surface of the vehicle body B, so that the loop coil 42 detects the magnetic flux generated from the vehicle body surface current. Consisting of:

A part of the loop coil 42 is connected to the case 40 by a shorting wire 44, and the output end 4
6 is connected to the core wire 50 of the coaxial cable 48. A capacitor 52 is provided in a part of the loop coil 42, and the frequency of the loop coil 42 is adjusted to a desired frequency to be measured (60M in the illustrated example).
Hz) to improve pickup efficiency.

By moving the probe P along the surface of the vehicle body B as described above and rotating its angle at each measurement point, it becomes possible to accurately determine the surface current distribution on the vehicle body surface and its direction. In FIG. 22, the output of the probe P is amplified by a high frequency voltage amplifier 54, and the output voltage is measured by a high frequency voltage measuring device 56.

This coil output voltage is read by the meter indication value of the measuring device 56, and the voltage corresponding to this meter indication value is recorded by the XY recorder 58 as a surface current distribution in each part of the vehicle body.

The XY recorder 58 has a potentiometer 60
Signals indicating each position of the vehicle body are input from
It becomes possible to know the high frequency pickup current at each position.

FIG. 23 shows the declination angle θ between the high-frequency surface current I and the loop coil 42 of the pickup, and as shown in the figure, the magnetic flux φ in the current I is
2, the output voltage V is generated in the loop coil 42, and as shown in FIG.
That is, the maximum voltage is obtained when the surface current I and the pickup loop coil 42 are parallel, and by rotating the probe P at each measurement point, it is possible to know the direction of the surface current I when the maximum voltage is obtained.

FIG. 25 and FIG. 26 show the above-mentioned probe P.
Figure 25 shows the magnitude and direction of the high-frequency surface current generated in each part of the car body at a frequency of 60 MHz, which was determined from both the measurement results and the computer simulation.As is clear from Figure 25, the magnitude of the surface current is The distribution shows a high density along the edges of the vehicle body surface, and an extremely low density in the center of the flat plate.

Also, as shown in the current direction in FIG.
It is understood that each current is concentrated in a direction parallel to the edge of the vehicle body or in the direction of the connecting portion of each flat plate portion.

Note that the surface current decreases with distance from the edge of the flat metal plate of the car body, and considering the range of current reduction of 6 dB or less where good sensitivity can actually be obtained, for each characteristic, the surface current decreases with distance from the edge of the metal plate 6.0 cm from the edge. If it is below, it is possible to obtain extremely good sensitivity.

The present invention has been made based on the above knowledge, and two or more high-frequency pickups are disposed particularly in areas where surface current flows in a concentrated manner with high density.

Specific Embodiment FIG. 1 shows a first embodiment of a keyless entry device for a vehicle according to the present invention.

A characteristic feature of this embodiment is that there are two pickups 102 on both front pillars 100a and 100b of the vehicle body, each having a structure similar to that of the probe described above.
a and 102b to detect the surface current flowing concentratedly in the front pillar.

Here, the pickup 102 adjusts the reception band center to 60MHz, and uses an impedance matching circuit to receive only a narrow band of high-frequency surface current, thereby reducing the influence of interference waves such as FM broadcast waves or TV broadcast waves. ing.

In this embodiment, the vehicle keyless entry device includes a transmitter 104 that is operated by a user and a receiver 106 provided on the vehicle body.
The surface current induced in the vehicle body by the radio waves from 04 is detected by the pickup 102, and the surface current is detected by the receiver 106.
Electrical processing is performed by.

The oscillator 104 includes a crystal oscillation circuit 108 having an oscillation frequency of 60 MHz, and an RF amplifier 112 that amplifies this oscillation signal and supplies it to a transmitting antenna 110. Therefore, it is controlled.

That is, the transmitter 104 includes a key-operated switch 114 that can be turned on and off by the user, and a code setting circuit 116 receives a desired electrical input signal according to the operating procedure or timing of the switch 114.

The output of the code setting circuit 116 is
It is converted into a desired electrical signal by a coding circuit 118, and this coded signal controls the output of the RF amplifier 112 via a modulator 120.

Therefore, according to the illustrated transmitter 104, the user's keyless entry operation, that is, the switch 11
4, the desired modulated keyless entry signal is wirelessly propagated from the transmitting antenna 110.

On the other hand, a high frequency surface current is induced in the vehicle body by the radio waves from the transmitter 104, and the pickup 10
2a and 102b receive the wirelessly propagated keyless entry signal from this surface current, and
At 06, the received signal from the pick-up 102a remains unchanged, and the received signal from the pick-up 102b is corrected in phase by the phase difference correction circuit 122.
The received signal input to the mixer 123 and mixed by the mixer 123 is supplied to the RF amplifier 124,
The desired amplification effect is applied.

Then, the amplified signal is mixed in the mixer 126 with a local oscillation frequency signal of, for example, 59.545 MHz from the local oscillation circuit 128, and further amplified by the intermediate frequency amplification circuit 130.

This amplified signal is demodulated and detected by a detection circuit 132, and then a code set by the user is restored by a decoder circuit 134.

The receiver 106 outputs the keyless entry signal restored in this way as a control signal 1 used for locking or unlocking the door or for other purposes.
It is output as 36.

FIG. 2 shows the antenna directivity characteristics in the 60MHz frequency band of the vehicle keyless entry device according to this embodiment, and FIG.
02a (solid line) and pick-up 102b (dotted line)
B shows the characteristic curve obtained by combining the directivity characteristics of both pickups.

As is clear from figure A, pick-up 10
2a has good sensitivity characteristics on the right side of the vehicle body, and slightly weak sensitivity characteristics in the longitudinal direction of the vehicle body.

On the other hand, it is understood that the pickup 102b has a directivity characteristic completely opposite to that of the pickup 102a, and that both pickups have a relationship in which their sensitivity characteristics complement each other.

Therefore, by combining the directional characteristics of both pickups 102, it is possible to obtain an almost omnidirectional antenna characteristic as shown in FIG. becomes possible.

FIG. 3 shows antenna directivity characteristics of a vehicle keyless entry device according to a second embodiment of the present invention.

A feature of this embodiment is that the pickups are provided at both ends of the rear edge of the rear roof of the vehicle body.

As is clear from FIG. 3, in this embodiment as well, both pickups 406a and 406b compensate for each other's weak reception sensitivity.
Similar to the first embodiment, the directional characteristics of the vehicle keyless entry device are improved.

Further, FIG. 4 shows the antenna directivity characteristics of a vehicle keyless entry device according to a third embodiment of the present invention.

A feature of this embodiment is that the pickups are provided at the center of the front edge of the front roof and at the center of the rear edge of the rear roof.

As is clear from FIG. 4, the pick-up 406 provided at the center of the rear edge of the rear roof has good directivity toward the front of the vehicle, and the pick-up 500 provided at the center of the front edge of the front roof has good directivity toward the rear of the vehicle. It has directional characteristics.

Therefore, both pickups complement each other's weakly sensitive parts to achieve good antenna directivity characteristics.

FIG. 5 shows antenna directivity characteristics of a vehicle keyless entry device according to a fourth embodiment of the present invention.

A feature of this embodiment is that pick-ups are provided at the center of the front pillar and the rear edge of the rear roof.

As is clear from Fig. 5, the pick-up provided on the front peeler has good directivity in the left-right direction, and the pick-up 406 provided in the center of the rear edge of the rear roof has good directivity in the longitudinal direction of the vehicle. have

Therefore, it is understood that both pickups complement each other's directional characteristics.

FIG. 6 shows antenna directivity characteristics of a vehicle keyless entry device according to a fifth embodiment of the present invention.

A feature of this embodiment is that pick-ups are provided at the right front pillar of the vehicle body and at the right end of the rear edge of the rear roof.

As is clear from Fig. 6, the directional characteristics of the pick-up 102b provided on the right front pillar and the pick-up 4 provided on the right end of the rear roof edge
The directional characteristics of antenna 06b complement each other, and good antenna directional characteristics can be realized by both pickups.

FIG. 7 shows antenna directivity characteristics of a vehicle keyless entry device according to a sixth embodiment of the present invention.

A feature of this embodiment is that a push-up is provided at the right end of the leading edge of the front roof of the vehicle and at the right trunk hinge of the vehicle.

As is clear from FIG. 7, a pick-up 500a provided at the right end of the front edge of the front roof and a pick-up 204 provided at the right trunk hinge.
The two pick-ups complement each other's directional characteristics, and both pickups achieve good antenna directional characteristics for a vehicle keyless entry device.

In the above embodiment, a case has been described in which two pick-ups are provided on the vehicle body, but the present invention is not limited to this, and it is also suitable to provide three or more pick-ups on the vehicle body.

Further, the installation position of the pick-up is not limited to the above embodiments, but may be any position as long as it can detect the high frequency surface current induced in the vehicle body by radio waves from the transmitter.

Mounting structure of the pick-up Next, the structure of mounting the pick-up on each part of the vehicle body will be explained.

First, the details of the structure for mounting the pickup to the front pillar will be explained based on FIGS. 8 to 10.

FIG. 8 schematically shows how the pick-up according to the present invention is installed, and the high-frequency pick-up 102 is attached to the front pillar 100 that supports the ceiling board.
In this installation example, the high frequency pickup 102 is an electromagnetic pickup including a loop coil.

As is clear from the cross-sectional view of FIG. 9, the pillar 100 includes a pillar leg plate 150 formed into a hollow rectangular prism serving as its main pillar. A windshield molding 152 is fixed to the outer surface of the vehicle body of the pillar leg plate 150, and a windshield 154 is held by this molding 152.

Further, a weather strip rubber 156 is fixed to the rear side of the vehicle body of the pillar leg plate 150, and the rubber 156 ensures watertightness between the pillar leg plate 150 and the side glass 158.

Further, a front pillar garnish 160 is attached to the vehicle interior side of the pillar leg plate 150 to hide the surface of the pillar leg plate 150 and maintain an aesthetic appearance.

A characteristic feature of this installation is that the high-frequency pick-up of the front pillar 100 is arranged along the longitudinal direction of the pillar, and in the illustrated example, the electromagnetically coupled high-frequency pick-up 102 is inserted into the hollow space of the pillar leg plate 150. has been done.

As is clear from FIGS. 9 and 10, the high-frequency pickup 102 has a structure in which a loop coil 164 forming an antenna element is provided inside a case 162 made of a conductor, and the case 162 absorbs magnetic flux from the outside. The shield has an opening 162a on one side, and this opening 162a
The loop coil 164 is exposed and placed close to the pillar, particularly the pillar leg plate 150, through which high-frequency surface current flows in a concentrated manner.

In the illustrated example, in order to insert the high-frequency pick-up 102 into the hollow square column of the pillar leg plate 150, a portion of the pillar leg plate 150 has an opening 150a.
is provided, and the high frequency pickup 10 is installed before the front pillar garnish 160 is fixed.
2 is inserted inside the pillar.

Then, case 1 of high frequency pickup 102
62 to the pillar leg plate 150, the case 162 has brackets 166 and 168 at both ends thereof.
are fixed by spot welding or the like, and both of these brackets 166, 168 are firmly screwed and fixed to the pillar leg plate 150 as shown.

Therefore, on this fixed plate, the loop coil 164 is connected to the opening 15 of the pillar leg plate 150.
The magnetic flux generated by the high-frequency surface current that flows intensively through the pillar leg plate 150 is effectively linked to the loop coil 164 .

Inside the case 162 is a circuit section 170 including a preamplifier etc. on the back side of the loop coil 164 described above.
This circuit 170 is supplied with power and signals for controlling the circuit from a cable 172, and a high frequency detection signal detected by the loop coil 164 is taken out from the coaxial cable 174. , is processed by a circuit similar to that used for the surface current distribution described above.

In the illustrated example, the loop coil 164 is a single-turn coil, and an insulating coating is applied to the coil so that it is placed in close contact with the pillar leg plate 150 while being electrically insulated.
A structure in which the magnetic flux is pressed against the edge of the pillar is preferable, and the magnetic flux generated by the high-frequency surface current that flows intensively in the pillar can be efficiently linked to the loop coil 164.

After the high-frequency pickup 102 is installed in the front pillar 100 as described above, the front pillar garnish 160 is attached to the pillar 100, and a structure that is no different in appearance from a normal pillar structure can be obtained. .

As a result, in the illustrated example, the high-frequency surface current that flows intensively in the front pillar of the automobile can be effectively detected by the loop coil arranged in the longitudinal direction of the pillar, without exposing the antenna to the outside at all. There is no interference, and reception in the high frequency band can be performed reliably.

In the above installation example, an electromagnetic coupling type pick-up is used as the high-frequency pick-up, but the present invention is a keyless entry device that detects the surface current of a pillar and receives radio waves from a transmitter. As a high frequency pickup, not only the above-mentioned electromagnetic coupling type but also an electrostatic coupling type can be used.

In the case of a capacitively coupled pickup, a detection electrode is arranged along the longitudinal direction of the pillar in each of the above figures with an air layer or an insulating layer interposed between them, and the capacitance formed between the pillar surface and the detection electrode is A high-frequency surface current is extracted to the detection electrode side through the sensor, thereby making it possible to extract a high-frequency signal at a carrier frequency of 60 MHz, which is normally used by keyless entry devices for signal propagation.

Next, the details of the structure for attaching the pickup to the trunk lid will be explained based on FIGS. 11 to 13.

In FIG. 11, the trunk hinge 200 has one end pivotally supported by the main body, and the other end fixed to the trunk lid 202, forming a pivot support for the trunk lid 202.

A feature of this installation example is that a pickup 204 is provided on the trunk hinge.

In this installation example, a torsion bar 206 is provided on the pivot side of the trunk hinge 200, and performs a positioning and moderating action when the trunk lid 20 is opened.

As is well known, there is a watertight weather strip rubber 208 between the trunk lid 202 and the vehicle body.
is provided to prevent rainwater from entering through the rear glass 210.

In this installation example, the pick-up 204 is fixed on the outside along the longitudinal direction of the trunk hinge 200, that is, on the trunk room side, and the loop coil 212 provided inside has its longitudinal direction aligned with the longitudinal direction of the trunk hinge 200. In this installation example, the surface current flowing through the trunk hinge 200 can be reliably and highly efficiently supplemented by the loop coil 212.

The pick-up 204 includes a case 214 and a circuit section 216 as in the example of installation on the front pillar, and the opening side of the case 214 is connected to the trunk hinge 20.
They are facing toward 0.

Brackets 218 and 220 are fixed at both ends of the opening of case 214, and one ends of both brackets 218 and 220 are firmly fixed to track hinge 200 by screwing.

Therefore, it is understood that only the magnetic flux induced from the surface current flowing through the trunk hinge 200 is captured in the case 214, and that magnetic flux from the outside is reliably shielded by the case 214.

The loop coil 212 is attached to the trinkle hinge 20
It is preferable that the hinge 200 be provided along the curvature of the hinge 200 and have a shape that matches the curvature of the hinge 200.

As described above, the circuit 216 is supplied with power for controlling the circuit and from the signal cable 222, and the high frequency detection signal taken out by the loop coil 212 is taken out from the coaxial cable 224, and the same circuit as described above is supplied. Processed by.

As described above, according to this installation example, since the surface current is detected by picking up from the trunk hinge, which is unrelated to the detection of vehicle surface current in the past, the antenna of the vehicle keyless entry device is It becomes possible to reliably receive radio waves from the transmitter without being exposed to the outside.

FIG. 13 shows another example of attaching the pickup to the trunk hinge, and the same parts as in FIG. 12 are given the same reference numerals, and their explanation will be omitted.

A characteristic feature of this setting example is that a pickup 300 is disposed on the back side of the trunk hinge 200, and a loop coil 304 and a circuit section 306 are included inside the case 302, and are connected by brackets 308 and 310. Trunk hinge 2
It is firmly fixed to the back side of 00.

This installation example has the advantage that the pick-up 300 does not protrude from the trunk hinge 200 toward the trunk room, and does not come into contact with or damage luggage or other objects stored in the trunk.

Next, details of the rear roof mounting structure of the pickup will be explained based on FIGS. 14 to 17.

In the figure, a ceiling plate 400 is shown in an exposed state, and this metal ceiling plate 400 is connected to a rear glass 404 with a rear window frame 402 as its peripheral edge.

This installation example is characterized in that a high frequency pickup 406 is cut inward from the edge of the rear window frame 402 in an area within 6.0 cm.

Similar to the above installation example, the pickup 406 includes a case 408, a loop coil 410, and a circuit section 41.
2, cable 414, coaxial cable 416, and brackets 418 and 420.

FIG. 16 shows a cross-sectional view of the pick-up 406 fixed to a ceiling board, and the ceiling board includes a roof panel 422, and the aforementioned rear window frame 402 is fixed to one end of this roof panel 422. Further, the rear glass 404 is fixed to the roof panel 422 via a fastener 424 and a dam 426, and the fastener 424
and dam 426 are uniformly attached by adhesive 428. Further, a molding 430 is fixed between the roof panel 422 and the rear glass 404.

In this installation example, in order to arrange the loop coil 410 of the pick-up 406 to face the peripheral edge of the rear window frame 402, an opening 402a is provided in a part of the rear window frame 402, and the case 408 of the pick-up 406 is formed in this opening 402a. Insert and place.

An opening 408a is provided in the case 408 so that the longitudinal side of the loop coil 410 is exposed, and a portion of the loop coil 410 exposed from the case 408 made of a conductive material is exposed to the rear window frame 402. It will be placed close to and opposite to the edge of the opening.

After the pick-up 406 is assembled into the exposed ceiling board, especially the rear window frame 402, as described above, the roof garnish 432 is fixed to the ceiling board, and the ends of the roof garnish 432 and the rear window frame 402 are fixed. Edgemol 434 is fixed to the.

Next, details of the front roof installation structure of the pickup will be explained based on FIGS. 18 and 19.

In this installation example, the pickup 500 is placed in a service hole 502a of a head panel 502 provided at the tip of the ceiling plate 400.

As is clear from FIG. 19, a windshield 154 is fixed to the roof panel 422 of the ceiling board via a dam 504, and as is well known, a molding 508 is fixed to the roof panel 422 and the windshield 154 via a stopper 506. connecting between.

The pickup 500 in this installation example has a configuration similar to that of the first embodiment, and the case 51
0, a loop coil 512, and a circuit section 514.

And pick up 500 loop coil 51
2 are fixed inward from the periphery of the header inner panel 502 at a distance of 6.0 cm, thereby making it possible to reliably detect the surface current of the header inner panel 502 which is concentrated at high density. can.

[Effects of the Invention] As explained above, according to the vehicle keyless entry device according to the present invention, it is possible to provide two or more pick-ups dedicated to the vehicle keyless entry device without damaging the appearance of the vehicle body. It becomes possible to obtain good directional characteristics.

Moreover, it is possible to avoid a decrease in radio broadcast reception sensitivity due to the conventional method of dividing the radio broadcast wave reception antenna into two, and also to narrow the pickup reception band to reduce the influence of interference waves.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a vehicle keyless entry device according to a first embodiment of the present invention, FIG. 2 is a directional characteristic diagram of a pickup used in the vehicle keyless entry device according to the first embodiment, and FIG. FIG. 4 is a directional characteristic diagram of a vehicle keyless entry device according to a second embodiment of the present invention, FIG. 4 is a directional characteristic diagram of a vehicle keyless entry device according to a third embodiment of the present invention, and FIG. 4 is a directional characteristic diagram of a vehicle keyless entry device according to a fifth embodiment of the present invention, and FIG. 6 is a directional characteristic diagram of a vehicle keyless entry device according to a fifth embodiment of the present invention. Directional characteristic diagrams of the keyless entry device, FIGS. 8 to 10 are explanatory diagrams of the front pillar mounting structure of the pickup used in the vehicle keyless entry device according to the present invention, and FIGS. 11 to 10 are
FIG. 13 is an explanatory diagram of the mounting structure of the pick-up used in the vehicle keyless entry device according to the present invention to the trunk hinge, and FIGS. 14 to 17 are illustrations of the pick-up used in the vehicle keyless entry device according to the present invention. 18 and 19 are explanatory diagrams of a front roof mounting structure of a pick-up used in the vehicle keyless entry device according to the present invention, and FIG. 20 is a conventional general vehicle keyless entry device. 21 is an explanatory diagram showing the surface current I generated in the vehicle body B by the radio wave W from the transmitter,
Fig. 22 is an explanatory diagram of a probe and its processing circuit for determining the distribution of car body surface current having the same configuration as the pick-up used in the present invention, and Fig. 23 is an electromagnetic coupling between the surface current I and the pick-up loop coil. An explanatory diagram showing the state, Fig. 24 is a characteristic diagram showing the directivity characteristics of the loop antenna in Fig. 23, Fig. 25 is an explanatory diagram showing the distribution characteristics of the surface current intensity, and Fig. 26 is an explanatory diagram showing the direction of the surface current. It is a diagram. 100...Front pillar, 102,204,
300, 406, 500... pick up, 10
4... Transmitter, 106... Receiver, 200... Trunk hinge, 400... Ceiling board.

Claims (1)

[Claims] 1. A keyless entry device for a vehicle that automatically locks and unlocks a door by receiving a code signal using radio waves from a transmitter, the vehicle body having at least two pick-ups that detect surface current. A keyless entry device for a vehicle, wherein the radio wave reception is performed by detecting, in the pick-up, a surface current induced in a vehicle body by the radio waves. 2. The keyless entry device for a vehicle according to claim 1, wherein the pick-ups are arranged along the longitudinal direction of the front pillars on both sides of the vehicle body. 3. The keyless entry device for a vehicle according to claim 1, wherein the pick-up is arranged along the periphery of the vehicle roof. 4. In the device according to claim 1,
A pick-up is a vehicle keyless entry device that is located at the center of the front pillar and rear edge of the rear roof. 5. The keyless entry device for a vehicle according to claim 1, wherein the pick-up is disposed at the front roof side end and at the trunk hinge on the same side.