JPH053507B2 - - 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. 18, 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 keyless entry signal receiver 24.

As a result, an audio signal 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 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 mainly for the radio broadcast wave reception band, especially the FM band (76 to 90MHz), so it is difficult for general vehicle keyless entry devices to propagate code signals. Sufficient sensitivity may not be obtained at the carrier frequency of the radio waves used (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 unrealistic to install a new pole antenna. It is.

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
Moreover, it is an object of the present invention to provide a keyless entry device for a vehicle that has excellent operability.

[Means for Solving the Problems] In order to achieve the above object, the keyless entry device for a vehicle body according to the present invention detects a surface current induced in the vehicle body by the radio waves when receiving radio waves from a transmitter. It is characterized by being carried out in a pick-up.

[Function] As is clear from the above-described configuration, according to the vehicle keyless entry device according to the present invention, radio wave reception is performed by a pick-up that detects a vehicle body 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.

Therefore, it is possible to provide a pick-up exclusively for the vehicle keyless entry device, and by setting the receivable frequency of the pick-up 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 19 to 24 show the process of determining the most efficient pick-up installation position by examining the surface current distribution characteristics of the vehicle body.

FIG. 19 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 is induced in each part of the car body depending on the strength of the electromagnetic wave. Among these radio waves, the target is 60MHz radio waves, 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 in the vehicle body in such a specific high frequency band, and installs a high frequency pickup in a part where the surface current density is high and there is little noise. Calculator 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. .

Fig. 20 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.

As described above, by moving the probe P along the surface of the vehicle body B and rotating its angle at each measurement point, it is possible to accurately determine the surface current distribution and its direction on the vehicle body surface. In FIG. 20, 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.

A signal indicating each position on the vehicle body is inputted to the XY recorder 58 from a potentiometer 60, making it possible to know the high frequency pickup current at each position.

FIG. 21 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 θ is 0 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. 23 and FIG. 24 show the above-mentioned probe P.
The figure shows the magnitude and direction of the high-frequency surface current generated in each part of the car body at a frequency of 60MHz, which was determined from both the measurement results and the simulation using a computer.As is clear from Figure 23, the magnitude of the surface current The distribution shows a high density along the edge line of the surface of the vehicle body, and an extremely low density in the center of the flat plate part.

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 high-frequency pickups are arranged particularly in areas where surface currents flow in a concentrated manner.

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

A feature of this embodiment is that a pickup 102 having a configuration similar to the probe described above is provided on the left front pillar 100 of the vehicle body 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
2 receives the radio-propagated keyless entry signal from this surface current and supplies it to the RF amplifier 124 of the receiver 106, where it is subjected to a desired amplification effect.

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 restored keyless entry signal as a control signal 136 used for locking or unlocking the door or for other purposes.
is output as

Figure 2 shows the 60M pick-up provided on the left front pillar of the vehicle body in the first embodiment.
It shows the antenna directivity characteristic in the Hz frequency band, and as is clear from the characteristic curve 138,
It has good sensitivity characteristics on the right side of the vehicle body, and slightly weaker sensitivity characteristics in the longitudinal direction of the vehicle body.

Therefore, in the vehicle keyless entry device according to this embodiment, a strong sensitivity characteristic appears on the driver's seat side where keyless entry operations are often performed, and good operability of keyless entry operations is ensured.

Next, the details of the structure for mounting the pickup to the front pillar will be explained based on FIGS. 3 to 5.

FIG. 3 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 panel.
In this embodiment, the high frequency pickup 102 is an electromagnetic pickup including a loop coil.

As is clear from the cross-sectional view of FIG. 4, 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 embodiment is that the high-frequency pick-up of the front pillar 100 is disposed along the longitudinal direction of the pillar, and in the illustrated example, an electromagnetically coupled high-frequency pick-up 102 is provided in the hollow interior of the pillar leg plate 150. It has been inserted.

As is clear from FIGS. 4 and 5, the high-frequency pickup 102 has a structure in which a loop coil 164 forming an antenna element is provided in a case 162 made of a conductor.
62 shields magnetic flux from the outside, and has an opening 162a on one side, and the loop coil 164 is exposed through this opening 162a, and the high-frequency surface current concentrates on the pillar, especially the pillar leg plate 1.
50.

In the illustrated example, a portion of the pillar leg plate 150 has an opening 150 in order to insert the high-frequency pick-up 102 into the hollow rectangular prism of the pillar leg plate 150.
A is provided, and the high frequency pickup 1 is installed before the front pillar garnish 160 is fixed.
02 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, in this fixed upper 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, which is disposed close to the 0a half surface.

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 section 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 sent to the coaxial cable 174.
and processed by a circuit similar to that used in 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 that generates 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 embodiments, 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 with an air layer or an insulating layer in between, and the electrostatic charge formed between the pillar surface and the detection electrode is A high-frequency surface current is extracted to the detection electrode side through the capacitor, 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.

Second Embodiment Next, a second embodiment of the vehicle key lens entry device according to the present invention will be described, in which a pick-up is disposed along the longitudinal direction of the periphery of the engine hood.

In this embodiment, when the pickup is disposed at the rear edge of the engine hood, its directional characteristic becomes highly sensitive toward the front of the vehicle.

Hereinafter, the details of the engine hood mounting structure of the pickup will be explained based on FIGS. 6 to 8.

In FIG. 6, one side of the engine hood 200 is rotatably supported by the vehicle body, and the inner surface of the peripheral edge on the windshield 154 side faces the front outer panel 202 in the closed state. The interior side of the front outer panel 202 is connected to the front inner pallet 204 and is connected to the windshield 15.
4 has a stopper 20 on the front outer panel 202
6, and a dam 208 is provided between the windshield 154 and the front inner panel 204.
is installed to prevent the intrusion of rainwater, etc.

Furthermore, a molding 210 is provided at the lower end of the windshield 154, as is well known.

The pickup 212 in this embodiment also has a similar structure to the high frequency pickup used in the first embodiment, and includes a case 214, a loop coil 216, and a circuit section 218.

The characteristic feature of this embodiment is that the pick-up 212 is fixed to the peripheral edge of the engine hood 200 on the front outer panel 202 side, particularly inward from the edge, within a distance of 6.0 cm. This makes it possible to reliably detect the high-frequency current that flows in a highly concentrated manner around the engine hood.

FIG. 7 shows a pickup 2 according to this embodiment.
12 is shown, and FIG. 8 shows an external view of a high-frequency pickup for mounting the engine hood, the details of which are almost the same as those of the first embodiment. Yes, pick-up 212 is bracket 220,2
22, and the engine hood 2 by screws 224.
00, circuit control power and signals are supplied through a cable 226, and a high frequency detection signal is extracted through a coaxial cable 228.

In addition, in this embodiment, it is necessary that the installation position of the pick-up does not interfere with storage of the wiper blade.

Furthermore, in this embodiment, the configurations of the transmitter and receiver are the same as those in the first embodiment, so their explanation will be omitted.

Third Embodiment Next, a third embodiment of the vehicle keyless entry device according to the present invention, in which a pickup is disposed around the trunk lid, will be described.

In this embodiment, the directional characteristics of the pickup have good sensitivity toward the rear of the vehicle.

Hereinafter, the mounting structure of the pickup will be explained in detail based on FIGS. 9 to 11.

In FIG. 9, a watertight weather strip rubber 304 is provided between the trunk lid 300 and the rear tray panel 302 to prevent rainwater from entering through the rear window 306.

The space between the rear glass 306 and the rear tray panel 302 is made airtight with a dam 308 to prevent rainwater, sound, etc. from entering.
As is well known, a molding 310 is provided on the outer side of the lower end.

A characteristic feature of this embodiment is that a pick-up 312 is fixed to the edge of the surface of the trunk lid 300 facing the rear tray panel 302, and the pick-up 312 is an electromagnetic coupling type pick-up. It has a similar configuration to the pickup used.

As is clear from the figure, the loop coil 314 provided inside the pickup 312 is arranged so that its longitudinal direction coincides with the longitudinal direction of the trunk lid 300.

Here, the loop coil 314 is placed within 6.0 cm from the edge of the trunk lid 300,
In the present invention, the surface current flowing concentrated around the periphery of the trunk lid 300 can be captured by the loop coil 314 reliably and with high efficiency.

Furthermore, as is clear from FIG. 24, the direction of the car body surface current flows along its periphery, so in this embodiment, the loop coil 314
are arranged so that their longitudinal direction runs along the peripheral edge of the trunk lid 300.

Note that the high-frequency pickup in this embodiment has a case 316 made of a conductor like the pickup in the first embodiment, and this case 316
A loop coil 314 and a circuit section 318 are built in, and an opening 316a thereof faces toward the trunk lid 300.

Therefore, only the magnetic flux induced from the high-frequency surface current flowing around the periphery of the trunk lid 300 is captured inside the case 316, and the magnetic flux from the outside is reliably shielded by the case 316.

Power and signals are supplied to the circuit section 318 described above from a cable 320, and a high frequency detection signal is taken out from a coaxial cable 322 and processed by a circuit similar to that described in the first embodiment.

As described above, according to this embodiment, the high-frequency surface current is detected from inside the trunk lid by high-frequency pickup, so the key entry signal can be received without protruding the antenna device to the outside. It becomes possible to do this reliably.

FIG. 10 shows the pick-up 3 according to this embodiment.
12 is shown, and the same parts as in FIG. 9 are designated by the same reference numerals, and their explanation will be omitted.

In the same figure, case 3 of pick-up 312
16 Attach a bracket 32 to the both sides using bolts, etc.
4,326 are provided, and the brackets 324,3
26 and the inner plate of the trunk lid 300 are screwed 328
By being fixed by
12 is securely set inside the traction lid 300.

Therefore, it is preferable that the high frequency pickup 312 be constructed as shown in FIG.

Fourth Embodiment Next, a fourth embodiment of the vehicle keyless entry device according to the present invention, in which a pickup is provided around the rear roof of the vehicle body, will be described.

In this example, when the pick-up is installed at the right end of the rear roof line, the receiving sensitivity of the vehicle keyless entry device has good characteristics toward the right side of the vehicle body, that is, toward the driver's seat side where there are many opportunities for keyless entry operations. However, it is understood that this is a suitable installation position.

Hereinafter, the details of the rear roof mounting structure of the pickup will be explained based on FIGS. 12 to 15.

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

As in the first embodiment, the pick-up 406
Case 408, loop coil 410, circuit section 4
12, cable 414, coaxial cable 416, and brackets 418 and 420.

FIG. 14 shows a cross-sectional view of the pick-up 406 fixed to a ceiling board, 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 embodiment, in order to arrange the roof 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. The opening line portions are arranged close to each other and opposite to each other.

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.

The keyless entry signal from the pickup installed as described above is processed by the same circuit as in the first embodiment.

Fifth Embodiment Next, a fifth embodiment of the vehicle keyless entry device according to the present invention, in which a pickup is installed on the front roof, will be described.

In this example, when the pick-up is installed at the right end of the front roof, it has good sensitivity characteristics toward the right side of the vehicle body, that is, on the driver's seat side where keyless entry operations are often performed. It is understood that this is a suitable installation location.

The details of the pick-up control roof installation structure will be described below with reference to FIGS. 16 and 17.

In this embodiment, the pickup 500 is placed in a service hole 502a of a header inner panel 502 provided at the tip of the ceiling plate 400.

As is clear from FIG. 17, 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 embodiment has a structure similar to that of the first embodiment, and the case 51
0, a loop coil 512, and a circuit section 514.

And the loop coil 5 of Pickup 500
12 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 keyless entry device for a vehicle according to the present invention, it is possible to provide a pick-up dedicated to the keyless entry device for a vehicle without damaging the appearance of the vehicle body. By dividing the radio broadcast wave receiving antenna into two, a decrease in radio broadcast reception sensitivity can be avoided, and the pickup reception band can be narrowed to reduce the influence of interfering radio waves.

[Brief explanation of drawings]

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 FIGS. FIG. 5 is an explanatory diagram of the vehicle body mounting structure of the pickup used in the vehicle keyless entry device according to the first embodiment, and FIGS. 6 to 8 are diagrams showing the vehicle keyless entry device according to the second embodiment of the present invention. 9 to 11 are explanatory diagrams of the vehicle body mounting structure of the pickup used in the vehicle keyless entry device according to the third embodiment of the present invention. FIGS. 12 to 15 are explanatory diagrams of the vehicle body mounting structure of the pickup used The figure is an explanatory diagram of a pick-up vehicle body mounting structure used in the vehicle keyless entry device according to the fourth embodiment of the present invention, and FIGS. 16 and 17 are the vehicle keyless entry device according to the fifth embodiment of the present invention. Fig. 18 is a configuration diagram of a conventional general vehicle keyless entry device, and Fig. 19 shows a surface current I generated on the car body B by radio waves W from a transmitter. FIG. 20 is an explanatory diagram of a probe and its processing circuit for determining the distribution of car body surface current, which has the same configuration as the pickup used in the present invention, and FIG. 21 shows a loop between the surface current I and the pickup. Explanatory diagram showing the state of electromagnetic coupling with the coil, 2nd
2 is a characteristic diagram showing the directivity characteristics of the loop antenna in FIG. 21, FIG. 23 is an explanatory diagram showing the distribution characteristics of the surface current intensity, and FIG. 24 is an explanatory diagram showing the direction of the surface current. 100...Front pillar, 102, 212,
312,406,500...Pickup, 10
4... Transmitter, 106... Receiver, 200... Engine hood, 300... Trunk lid, 40
0...Ceiling board.

Claims (1)

[Claims] 1. In 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 radio wave reception is based on a surface current induced in the vehicle body by the radio waves. A keyless entry device for a vehicle, characterized in that the keyless entry device is operated by a pickup that detects. 2. The keyless entry device for a vehicle according to claim 1, wherein the pick-up is arranged along the longitudinal direction of the front pillar. 3. The keyless entry device for a vehicle according to claim 1, wherein the pick-up is disposed along the longitudinal direction of the periphery of the engine hood. 4. The keyless entry device for a vehicle according to claim 1, wherein the pick-up is disposed along the longitudinal direction of the trunk lid. 5. The keyless entry device for a vehicle according to claim 1, wherein the pick-up is arranged along the longitudinal direction of the roof.