JP5531717B2 - Smart entry system - Google Patents

Description

  The present invention relates to a smart entry system.

  The smart entry system enables a user to lock / unlock a door and the like without taking a key by wireless communication between an electronic key and a vehicle using radio waves. In this smart entry system, the in-vehicle transceiver transmits a low frequency request signal, and when the electronic key receives the request signal, the electronic key transmits the ID code signal to the in-vehicle transceiver. When the vehicle-mounted transceiver receives this ID code signal, the vehicle-mounted transceiver performs identification / collation of the ID code and outputs an operation instruction signal to each control unit in order to lock / unlock the door and the like. .

  And in the smart entry system of patent documents 1, a pair of loop coil antennas are used as a low frequency antenna for transmitting a request signal, and these antennas are mounted in the left and right doors. As a result, both an in-vehicle communication area with the electronic key in the vehicle interior and an out-of-vehicle communication area with the electronic key in front of the doors on the left and right sides of the vehicle are secured.

Japanese Patent Laying-Open No. 2006-22606 (FIG. 3)

  However, as in Patent Document 1, if the low frequency antenna is to be arranged inside the left and right doors, the inside of the door is narrow, and there is a risk that the arrangement location cannot be secured. In addition, the wiring between the low-frequency antenna and the vehicle-mounted transceiver must pass through the connecting portion between the door and the vehicle body, and there is a problem that the wiring cannot be freely performed. For this reason, it is desirable to arrange the low-frequency antenna outside the door.

  SUMMARY OF THE INVENTION In view of the above, the present invention has an object to provide a smart entry system that can secure a vehicle interior communication area and an external communication area in front of the doors on the left and right sides of the vehicle without arranging a low frequency antenna inside the door. And

In order to achieve the above object, according to the first aspect of the present invention, the low-frequency antenna (3) is a central part in the vehicle width direction of the vehicle, and the center pillars (12, 13) on the left and right sides of the vehicle and the front seat A gap formed on the vehicle interior side between the doors (18, 19) or a vehicle interior side between the center pillars (12, 13) on the left and right sides of the vehicle and the rear seat doors (14, 15). It is placed at a position facing the gap,
The low frequency antenna (3) has a first coil (4) and a second coil (5) that radiate a magnetic field in different directions, and the coil opening surface (4a) of the first coil (4) faces the gap. And an antenna configured such that the coil opening surface (5a) of the second coil (5) faces the vehicle longitudinal direction,
The on-vehicle transceiver (2) transmits radio waves from the first and second coils (4, 5) so that the radio waves are radiated independently from the first and second coils (4, 5), respectively. It is characterized by controlling timing.

  In the present invention, when a radio wave is transmitted alone from the first coil, a magnetic field propagates outside the vehicle so as to spread around the gap between the center pillar and the door, and when a radio wave is transmitted alone from the second coil, And a magnetic field propagates outside the vehicle so as to avoid the center pillar from the rear seat window and spread in the vehicle front-rear direction. Therefore, by combining the propagation areas of the magnetic field from both the first and second coils, the area in front of the door on the left and right sides of the vehicle can be included in the propagation area of the magnetic field. Can be secured.

  Moreover, in this invention, since a low frequency antenna is arrange | positioned in the center part of the vehicle width direction of a vehicle, a vehicle interior communication area is securable.

  Therefore, according to the present invention, it is possible to secure the vehicle exterior communication area and the vehicle interior communication area in front of the doors on the left and right sides of the vehicle without arranging the low frequency antenna inside the door.

  In the present invention, the low-frequency antenna is arranged not in the door, but in the center of the vehicle outside the door, so that compared to the case where the antenna is arranged inside the door, securing the antenna installation location and wiring It can be easily handled.

  Further, in the technique described in Patent Document 1, two antennas are used to secure the vehicle exterior communication area and the vehicle interior communication area in front of the doors on both the left and right sides of the vehicle, but according to the present invention, one antenna is used. The vehicle exterior communication area and the vehicle interior communication area in front of the doors on the left and right sides of the vehicle can be secured.

  For example, as shown in claim 2, the low-frequency antenna (3) is arranged at a first virtual straight line (31) extending in the vehicle length direction through the vehicle center in the vehicle width direction, and center pillars on the left and right sides of the vehicle. Between the center pillars (12, 13) and the rear seat doors (14, 15) on the vehicle interior side between the (12, 13) and the front seat doors (18, 19) It can be set as the position which the 2nd virtual straight line (32) which connected the gap | interval which has arisen in the vehicle interior side in the middle intersects.

In invention of Claim 3, as a low frequency antenna,
The vehicle interior side between the center pillar (12) on the left side of the vehicle and the front door (18) or the rear seat door (14), which is located on the vehicle left side of the vehicle width direction center of the vehicle. A first antenna (61) that is disposed at a position facing the gap on the left side of the vehicle, and that is configured by a coil having at least a coil opening surface facing the gap on the left side of the vehicle;
The position on the right side of the vehicle in the vehicle interior relative to the center in the vehicle width direction of the vehicle, the vehicle interior side between the center pillar (13) on the right side of the vehicle and the front seat door (19) or the rear seat door (15) The second antenna (62) is arranged at a position facing the gap on the right side of the vehicle, and at least the coil opening surface is constituted by a coil facing the gap on the right side of the vehicle.

  In the present invention, when a radio wave is transmitted from the first antenna, a magnetic field propagates outside the vehicle so as to spread around the gap between the center pillar on the left side of the vehicle and the door, and when the radio wave is transmitted from the second antenna, Since the magnetic field propagates to the outside of the vehicle so as to spread around the gap between the center pillar on the right side of the vehicle and the door on the outside of the vehicle, it is possible to secure an outside communication area in front of the doors on the left and right sides of the vehicle.

  Moreover, in this invention, since a low frequency antenna is arrange | positioned in a vehicle interior, a vehicle interior communication area is securable.

  Therefore, according to the present invention, it is possible to secure the vehicle exterior communication area and the vehicle interior communication area in front of the doors on the left and right sides of the vehicle without arranging the low frequency antenna inside the door.

  In the present invention, the low-frequency antenna is arranged not in the door but in the vehicle interior outside the door. Therefore, compared with the case where the antenna is arranged in the door, securing the antenna installation location and wiring are ensured. It can be done easily.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is a figure showing the whole smart entry system composition in a 1st embodiment of the present invention. It is an enlarged view of the low frequency antenna in FIG. It is sectional drawing which shows the clearance gap between a center pillar and a rear seat door. It is a time chart of the radio wave transmission from the low frequency antenna 3 by the vehicle-mounted transceiver in FIG. (A) is a figure which shows magnetic field distribution when radio waves are transmitted from the low frequency antenna 3 in FIG. 1 toward the outside of the passenger compartment, and (b) is when only the second coil 5 of the low frequency antenna 3 is driven. It is a figure which shows a magnetic field distribution, (c) is a figure which shows a magnetic field distribution when only the 1st coil 4 of the low frequency antenna 3 is driven. It is a figure which shows magnetic field distribution when radio waves are transmitted toward the outside of the passenger compartment from the low frequency antennas 41 and 42 of the comparative example. It is a figure which shows the simulation result of the magnetic field vector inside and outside a vehicle when radio waves are transmitted from the uniaxial antenna 51 which forms the coil whose normal line direction of a coil opening surface is a vehicle width direction. It is a figure which shows the simulation result of the magnetic field vector inside and outside the vehicle when the electromagnetic wave is transmitted from the uniaxial antenna 52 which forms the coil whose normal direction of the coil opening surface is the vehicle length direction. It is a figure for demonstrating the vehicle mounting position of the low frequency antenna 3 of 2nd Embodiment, Comprising: It is a figure which shows the communicable distance outside a vehicle when the position of the low frequency antenna 3 is changed in the vehicle front-back direction. It is a figure for demonstrating the vehicle mounting position of the low frequency antenna 3 of 2nd Embodiment, Comprising: It is a figure which shows the communicable distance outside a vehicle when the position of the low frequency antenna 3 is changed in the vehicle front-back direction. It is a figure for demonstrating the vehicle mounting position of the low frequency antenna 3 of 2nd Embodiment, Comprising: It is a figure which shows the communicable distance outside a vehicle when the position of the low frequency antenna 3 is changed in the vehicle left-right direction. It is a figure for demonstrating the vehicle mounting position of the low frequency antenna 3 of 2nd Embodiment, Comprising: It is a figure which shows the communicable distance outside a vehicle when the position of the low frequency antenna 3 is changed in the vehicle left-right direction. It is a figure for demonstrating the direction of the low frequency antenna 3 of 3rd Embodiment, Comprising: It is a measurement result of the radiation electric field strength in the position away from the low frequency antenna 3 by the predetermined distance. It is a figure which shows the whole smart entry system structure in 4th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are given the same reference numerals in the drawings in order to simplify the description.

(First embodiment)
FIG. 1 shows the overall configuration of the smart entry system of the present embodiment. In addition, the arrow which shows front and rear, right and left in a figure has shown the front and rear, right and left direction of the vehicle.

  The smart entry system includes a portable transmitter 1, a vehicle-mounted transceiver 2, and a low frequency antenna 3.

  The portable transceiver 1 is an electronic key possessed by a user.

  The on-vehicle transceiver 2 is mounted on the vehicle 10 and performs radio communication with the portable transceiver 1 by radio waves. The in-vehicle transceiver 2 is accommodated inside the instrument panel in front of the vehicle. The on-vehicle transmitter / receiver 2 of this embodiment performs discrimination / collation of a transmitter for transmitting radio waves from the low-frequency antenna 3, a receiver for receiving high-frequency radio waves from the portable transceiver 1, and an ID code. In addition, a function as a control device that outputs an operation instruction signal to each control unit is provided.

  The low-frequency antenna 3 is a transmission antenna that is mounted on the vehicle 10 and transmits low-frequency radio waves. Low frequency radio waves mean radio waves of 30 kHz to 300 kHz defined by the Radio Law. The low frequency antenna 3 is housed in a center console 11 located in the center of the vehicle interior, and is electrically connected to the in-vehicle transceiver 2 by wiring. The low-frequency antenna 3 is a single antenna that secures a vehicle interior communication area and a vehicle exterior communication area in front of the doors on the left and right sides of the vehicle. A detailed description of the low frequency antenna 3 will be described later.

  Although not shown, a back door transmission antenna for securing an out-of-vehicle communication area in front of the back door is disposed inside the back door of the vehicle 10.

  The smart entry system having such a configuration operates as follows.

  The in-vehicle transceiver 2 transmits a low frequency request signal from the low frequency antenna 3. By transmitting this request signal, a communication area with the portable transceiver 1 is formed. When the portable transceiver 1 receives a request signal within this communication area, the portable transceiver 1 transmits a high-frequency ID code signal, and the vehicle-mounted transceiver 2 receives this ID code signal.

  The vehicle-mounted transceiver 2 determines / collates the ID code, and outputs an operation instruction signal to each control unit in order to lock / unlock the door. Thereby, for example, when the user holds the door handle, the door is unlocked.

  Next, the low frequency antenna 3 will be described in detail. FIG. 2 shows an enlarged view of the low-frequency antenna 3.

  The low frequency antenna 3 is a biaxial antenna that radiates a magnetic field in the biaxial direction. Specifically, as shown in FIG. 2, the low-frequency antenna 3 includes a first coil 4 and a second coil 5, and a normal direction 4 b of a coil opening surface 4 a formed by the first coil 4; The angle formed by the normal direction 5b of the coil opening surface 5a formed by the second coil 5 is 90 °. Thereby, the low frequency antenna 3 has magnetic field radiation components orthogonal to each other.

  The first coil 4 and the second coil 5 are wound with conductive wires so as to intersect the same magnetic core 6. For example, a ferrite core is used as the magnetic core. The magnetic core 6 may be omitted, and the first coil 4 and the second coil 5 may be air core coils.

  Here, FIG. 3 shows a gap between the center pillar and the rear seat door. FIG. 3 is a cross-sectional view seen from above the vehicle. As shown in FIG. 3, the rear seat door 14 (15) and the front seat door 18 (19) are usually positioned so as to cover the outside of the center pillar 12 (13). A gap 16 (17) exists between the center pillar 12 (13) and the rear seat door 14 (15). Similarly, a gap 20 (21) exists between the center pillar 12 (13) and the front seat door 18 (19).

  As shown in FIG. 1, the low-frequency antenna 3 is a central portion in the vehicle width direction (left-right direction) of the vehicle 10, and is formed between the center pillars 12, 13 on the left and right sides of the vehicle and the rear seat doors 14, 15. It arrange | positions in the position which opposes the clearance gaps 16 and 17 which have arisen in the vehicle interior side between.

  Specifically, the low-frequency antenna 3 is positioned at a height of 4 cm from the vehicle floor panel and extends in the vehicle length direction through the vehicle center in the vehicle width direction, and both the left and right sides of the vehicle The center pillars 12, 13 and the rear seat doors 14, 15 are arranged at the intersections with the second virtual straight line 32 connecting the gaps 16, 17 generated on the vehicle interior side.

  The direction of the low frequency antenna 3 is such that the normal direction 4 b of the first coil 4 coincides with the second virtual line 32 and the normal direction 5 b of the second coil 5 coincides with the first virtual line 31. ing.

  In FIG. 4, the time chart of the radio wave transmission from the low frequency antenna 3 by the vehicle-mounted transceiver 2 is shown. The vehicle-mounted transceiver 2 has a drive circuit that drives the low-frequency antenna 3. This drive circuit has a control switch capable of switching and driving the first coil 4 and the second coil 5 with a time difference.

  And when the vehicle-mounted transceiver 2 forms the vehicle exterior communication area in front of the doors on both the left and right sides of the vehicle, the first and second coils 4 and 5 have a time to radiate radio waves independently. The radio wave transmission timing from the first coil 4 and the second coil 5 is controlled.

  Specifically, as shown in FIG. 4, the vehicle-mounted transceiver 2 causes radio waves to be transmitted (ON) alternately from the first coil 4 and the second coil 5. At this time, for example, the transmission time of each coil is set to 50 ms, the off time is set to 25 ms, the transmission frequency of each coil is set to 134 kHz, and the transmission output is set to 105 [dBμV / m @ 3 m], which is the upper limit of radio wave regulations.

  Moreover, when forming the vehicle interior communication area, the vehicle-mounted transceiver 2 sets the transmission output from each coil to be low so that the range in which the radio wave reaches is limited to the vehicle interior. In this case, radio waves may be transmitted simultaneously from the first coil 4 and the second coil 5, or alternatively, radio waves may be transmitted alternately.

  As described above, the in-vehicle transceiver 2 changes the propagation distance of the radio wave by switching the transmission output of the radio wave, and switches between the formation of the outside communication area and the formation of the vehicle interior communication area.

  Next, the communication area outside the vehicle of the low frequency antenna 3 of this embodiment will be described. FIG. 5A shows a magnetic field distribution around the front seat door outside the vehicle when radio waves are transmitted from the low frequency antenna 3 to the outside of the passenger compartment. FIG. 5B shows the magnetic field distribution when only the second coil 5 of the low frequency antenna 3 is driven, and FIG. 5C shows the case where only the first coil 4 of the low frequency antenna 3 is driven. The magnetic field distribution of is shown. These magnetic field distributions are the results of measurement using a magnetic field probe at a position 80 cm in height from the ground.

  In addition, the semicircle shown with the broken line in Fig.5 (a)-(c) is a curve with a radius of 70 cm from the doorknob of a front seat door, and the portable transceiver 1 and the vehicle-mounted transceiver 2 which a user carries outside a vehicle. The target communication area for good low-frequency communication is shown. A thick broken line in FIG. 5 indicates a boundary line of the low-frequency reception sensitivity 106 [dBμV / m] of the portable transceiver 1, and the area on the vehicle side becomes a communicable area.

  As shown in FIG. 5 (b), if radio waves are transmitted only from the second coil 5 whose normal direction 5b of the coil opening surface is the vehicle length direction (vehicle longitudinal direction), the center pillar 12 is avoided and only the vehicle longitudinal direction is avoided. The spread magnetic field distribution. For this reason, the communicable area covers the front and rear areas of the center pillar 12 in the target communication area.

  On the other hand, as shown in FIG. 5C, when radio waves are transmitted only from the first coil 4 whose normal direction 4b of the coil opening surface is in the vehicle width direction (vehicle left-right direction), a semicircle is drawn around the center pillar 12. The magnetic field distribution is as follows. For this reason, the communicable area covers the front area of the center pillar 12 in the target communication area.

  Therefore, in this embodiment in which radio waves are transmitted from the low-frequency antenna 3 so that radio waves are radiated independently from the first coil 4 and the second coil 5, respectively, as shown in FIG. A magnetic field distribution is formed by combining the magnetic field distribution when radio waves are transmitted from 4 and the magnetic field distribution when radio waves are transmitted from the second coil. As a result, it can be seen that the outside-communicable area of the present embodiment exceeds the target communication area and can communicate well.

  Incidentally, when radio waves are transmitted simultaneously from the first coil 4 and the second coil 5, a magnetic field distribution covering the target communication area as shown in FIG. 5A cannot be formed. Therefore, in order to secure the target communication area, it is important to radiate radio waves from the first coil 4 and the second coil 5 independently.

  Here, in FIGS. 6A and 6B, as a comparative example, uniaxial low-frequency antennas 41 and 42 are arranged at the center of the vehicle 10 in the vehicle width direction and at the center of the front seat door 18. The magnetic field distribution around the front seat door when one is mounted at the facing position is shown. FIG. 6A is a measurement result when the low frequency antenna 41 formed with a coil whose normal direction of the coil opening surface is a vehicle length direction is mounted, and FIG. 6B is a method of the coil opening surface. It is a measurement result when the low frequency antenna 42 formed by a coil whose line direction is the vehicle width direction is mounted.

  As shown in FIGS. 6A and 6B, even if a single-axis low-frequency antenna is simply mounted in the vehicle, the communicable area is about 40 cm from the doorknob, and the target communication area cannot be secured. Recognize. Further, it can be seen that even if the two types of coils shown in FIGS. 6A and 6B are combined, the target outside-vehicle communication area cannot be secured.

  Therefore, in order to secure a target outside vehicle communication area, as shown in FIG. 1, a biaxial low-frequency antenna in which the normal directions 4b and 5b of the coil opening surface are the vehicle width direction and the vehicle length direction, respectively. 3 is effectively arranged at the center of the second imaginary straight line 32 connecting the gaps 16 and 17 formed on the vehicle interior side between the center pillars 12 and 13 on the left and right sides of the vehicle and the rear seat doors 14 and 15. It is.

  Next, the mechanism of radio wave (magnetic field) propagation from the low frequency antenna 3 of this embodiment will be described.

  FIGS. 7A and 7B show the simulation results of the magnetic field vectors inside and outside the vehicle when radio waves are transmitted from the single-axis antenna 51 that forms a coil whose normal direction of the coil opening surface is in the vehicle width direction. 8A and 8B show the simulation results of the magnetic field vector inside and outside the vehicle when radio waves are transmitted from the uniaxial antenna 52 that forms a coil whose normal direction of the coil opening surface is the vehicle length direction. . The figure (a) is a result of the surrounding area of the front seat door 18 and the rear seat door 14 on the left side of the vehicle, and the figure (b) is an enlarged view of the areas A1 and A2 in the figure (a). The height of the single-axis antennas 51 and 52 from the floor panel was 4 cm, and the frequency of the radio wave was 134 kHz.

  As shown in FIGS. 7 (a) and 7 (b), when the normal direction of the coil opening surface corresponding to the first coil 4 of the low-frequency antenna 3 is a uniaxial antenna 51 in the vehicle width direction, a magnetic field is present in the vicinity of the pillar 12. Is the vehicle width direction, and the direction of the magnetic field is perpendicular to the gap formed between the pillar 12 and the door 14. Therefore, the magnetic field passes through the gap and propagates outside the vehicle so as to spread radially around the pillar 12.

  On the other hand, as shown in FIGS. 8A and 8B, when the normal direction of the coil opening surface corresponding to the second coil 5 of the low-frequency antenna 3 is the uniaxial antenna 52 in the vehicle length direction, the vicinity of the pillar 12 Since the direction of the magnetic field is the vehicle length direction and the direction of the magnetic field is horizontal with respect to the gap formed between the pillar 12 and the door 14, the magnetic field does not propagate from the gap to the outside of the vehicle. It propagates out of the vehicle in the front-rear direction avoiding the pillars from the window.

  From this, propagation to the outside of the vehicle is roughly divided into two depending on the direction of magnetic field radiation (vehicle length direction, vehicle width direction) from the low-frequency antenna, and forms a complementary propagation area with the center pillar as a base point. I understand that. The propagation area of complementary relationship is the front area of the center pillar and the front and rear areas of the center pillar among the target communication areas in front of the left and right doors.

  Therefore, by using a biaxial antenna that can combine the propagation characteristics of complementary relations with the center pillar as a base point, like the low-frequency antenna 3 of the present embodiment, it is possible to secure the vehicle exterior communication areas of the left and right doors of the vehicle.

  Further, if the target communication area is set as a semicircle centered on the front seat door knob, the center pillars 12 and 13 adjacent to the front seat door knob are used as base points, as in the low-frequency antenna 3 of the present embodiment. The propagation of the magnetic field is effective.

  As described above, according to the low frequency antenna 3 of the present embodiment, the vehicle interior communication area and the vehicle exterior communication areas on the front sides of the doors on the left and right sides of the vehicle can be secured without arranging the low frequency antenna inside the door. Therefore, as compared with the case where the low frequency antenna is arranged inside the door, it is possible to easily secure the antenna installation location and route the wiring.

  Further, in the technique described in Patent Document 1, two antennas are used to secure the vehicle interior communication area and the vehicle exterior communication areas on the left and right sides of the vehicle. According to the present embodiment, one antenna is used. With the low-frequency antenna 3, it is possible to secure a vehicle exterior communication area and a vehicle interior communication area in front of the doors on the left and right sides of the vehicle.

(Second Embodiment)
In the first embodiment, the vehicle mounting position of the low-frequency antenna 3 is the position of the intersection of the first virtual straight line 31 and the second virtual straight line 32. However, within the range where the target communicable area can be achieved as in this embodiment. Thus, the vehicle mounting position of the low frequency antenna 3 can be changed.

  First, the vehicle mounting position of the low frequency antenna 3 in the vehicle longitudinal direction will be described.

  9 and 10, the communicable distance outside the vehicle when the position of the low-frequency antenna 3 is changed in the vehicle longitudinal direction with the position of the intersection of the first virtual line 31 and the second virtual line 32 as a reference (0 cm). Indicates. 9B, as shown in FIG. 9A, only the first coil 4 in which the normal direction 4b of the coil opening surface is the vehicle width direction of the low frequency antenna 3 is driven to radiate a magnetic field. It is time, and the communicable distance at the position P1 in front of the pillar 12 is shown. 10B, as shown in FIG. 10A, only the second coil 5 in which the normal direction 5b of the coil opening surface of the low frequency antenna 3 is the vehicle length direction is driven to generate a magnetic field. It shows the communicable distance at the positions P2 and P3 where the angle formed by the straight line parallel to the vehicle width direction through the front seat door knob 18a is 30 ° in the vehicle longitudinal direction. These positions P1, P2, and P3 are determined based on the magnetic field propagation characteristics of the first coil 4 and the second coil 5. Further, since the shape of the vehicle is symmetrical, when the low-frequency antenna 3 is moved in the vehicle front-rear direction, the same communicable distance is measured on both the left and right sides of the vehicle, so the communicable distance on the left side of the vehicle was measured.

  As shown in FIG. 9B, in order to satisfy the target communication area of 70 cm centered on the front door knob 18a, when only the first coil 4 of the low frequency antenna 3 is driven and a magnetic field is emitted, It is necessary to mount the low-frequency antenna 3 in a range of −10 cm to +5 cm with the front direction of the vehicle being positive.

  Similarly, as shown in FIG. 10B, in order to satisfy the target communication area of 70 cm, when only the second coil 5 of the low-frequency antenna 3 is driven to emit a magnetic field, the front direction of the vehicle It is necessary to mount the low-frequency antenna 3 in the range of -7 cm to +5 cm with positive.

  From the above, the vehicle mounting position of the low frequency antenna 3 in the vehicle front-rear direction is based on the intersection of the first virtual line 31 and the second virtual line 32, and the front direction of the vehicle is positive and the rear direction is negative. Then, it can be changed to a position different from the reference within a range of −7 cm to +5 cm with respect to the reference.

  Next, the vehicle mounting position of the low frequency antenna 3 in the vehicle left-right direction will be described.

  11 and 12, the communicable distance outside the vehicle when the position of the low frequency antenna 3 is changed in the lateral direction of the vehicle with the position of the intersection of the first virtual line 31 and the second virtual line 32 as a reference (0 cm). Indicates. In FIG. 11B, as shown in FIG. 11A, only the first coil 4 in which the normal direction 4b of the coil opening surface is the vehicle width direction of the low frequency antenna 3 is driven to radiate a magnetic field. It shows the communicable distance at the front positions P4 and P5 with respect to the pillars 12 and 13 on the left and right sides of the vehicle. 12 (b), as shown in FIG. 12 (a), the magnetic field is generated by driving only the second coil 5 of the low frequency antenna 3 whose normal direction 5b of the coil opening surface is the vehicle length direction. It shows the communicable distance at positions P6 and P7 where the angle formed by the straight line parallel to the vehicle width direction through the front seat door knobs 18a and 19a on the left and right sides of the vehicle is 30 ° in the vehicle front direction. ing.

  As shown in FIG. 11B, in order to satisfy the target communication area of 70 cm centered on the front seat door knob 18a, when only the first coil 4 of the low frequency antenna 3 is driven to emit a magnetic field, It is necessary to mount the low-frequency antenna 3 in a range of -3 cm to +3 cm with the left direction of the vehicle being positive.

  Similarly, as shown in FIG. 12B, in order to satisfy the target communication area of 70 cm, when only the second coil 5 of the low-frequency antenna 3 is driven to emit a magnetic field, the left direction of the vehicle It is necessary to mount the low-frequency antenna 3 in the range of −3 cm to +3 cm, with positive.

  From the above, the vehicle mounting position of the low-frequency antenna 3 in the left-right direction of the vehicle is based on the intersection of the first virtual line 31 and the second virtual line 32, and the left direction of the vehicle is positive and the right direction is negative. Then, it can be changed to a position different from the reference within a range of −3 cm to +3 cm with respect to the reference.

(Third embodiment)
In the first embodiment, the direction of the low-frequency antenna 3 is such that the normal direction 4 b of the first coil 4 matches the second imaginary straight line 32, and the normal direction 5 b of the second coil 5 matches the first imaginary straight line 31. However, it does not have to be the same. As in the present embodiment, the coil opening surface 4a of the first coil 4 faces the vehicle longitudinal direction and the coil opening surface 5b of the second coil 5 is a gap between the center pillar and the door so that the target communicable area can be achieved. Can be changed to another direction.

  FIG. 13 shows the measurement result of the radiation electric field intensity at a position away from the low frequency antenna 3 by a predetermined distance. FIG. 13B shows the measurement results at the position indicated by the A-A ′ line 65 cm away from the first coil 4 of the low-frequency antenna 3 as shown in FIG. As shown in FIG. 13B, the magnitude of the radiated electric field intensity varies depending on the measurement position, and the range in which the decrease in electric field intensity from the peak value is within −5 dB is about 11 cm. The range of 11 cm is when the angle θ formed with the direction perpendicular to the line A-A ′ shown in FIG. 13A is within 10 ° as a result of calculation.

  Here, if the direction of the low frequency antenna 3 is changed with respect to the low frequency antenna 3 shown in FIG. 1, the intensity of the electric field incident on the gap 16 on the vehicle interior side between the center pillar 12 and the rear seat door 14 decreases. Therefore, in order to achieve a target communicable area with a decrease in electric field intensity incident on the gap 16 within -5 dB, when the distance from the low frequency antenna 3 to the gap is 65 cm, the coil opening surface of the first coil 4 If the angle formed between the ray direction 4b and the second virtual straight line 32 is within 10 ° in the vehicle longitudinal direction, the direction of the low-frequency antenna 3 can be arbitrarily changed.

(Fourth embodiment)
FIG. 14 shows the overall configuration of the smart entry system of the present embodiment. Below, a different point from 1st Embodiment is demonstrated.

  The smart entry system of this embodiment includes two low frequency antennas, a first antenna 61 and a second antenna 62. The two low-frequency antennas 61 and 62 are electrically connected to the vehicle-mounted transceiver 2 via electrical wiring. The two low-frequency antennas 61 and 62 are both uniaxial antennas, and have coils 63 and 64 in which the direction of radiation of the coil opening surface is one direction. These coils 63 and 64 correspond to the first coil 4 included in the low-frequency antenna 3 of the first embodiment.

  The first antenna 61 is disposed at a position on the left side of the vehicle with respect to the first virtual straight line 31 (the center in the vehicle width direction) of the vehicle interior, and the second antenna 62 is a first virtual line within the vehicle interior. It is arranged at a position on the right side of the vehicle with respect to the straight line 31.

  Further, the vehicle mounting position of the two low frequency antennas 61, 62 in the vehicle front-rear direction and the orientation of the coils 63, 64 of the two low frequency antennas 61, 62 are the first coil 4 of the low frequency antenna 3 of the first embodiment. The direction is the same.

  In other words, the first antenna 61 is disposed at a position facing the left-side gap 16 formed on the vehicle interior side between the center pillar 12 on the left side of the vehicle and the rear seat door 14. The coil 63 that forms the first antenna 61 has a coil opening surface that faces the gap 16 on the left side of the vehicle. In this example, the normal direction of the coil opening surface coincides with the second virtual straight line 32.

  The second antenna 62 is disposed at a position facing the gap 17 on the right side of the vehicle generated on the vehicle interior side between the center pillar 13 on the right side of the vehicle and the rear seat door 15. The coil 64 forming the second antenna 62 has a coil opening surface facing the gap 17 on the right side of the vehicle. In this example, the normal direction of the coil opening surface coincides with the second virtual straight line 32.

  In the present embodiment, when radio waves are transmitted from the first antenna 61, the magnetic field propagates outside the vehicle so as to spread around the gap 16 on the vehicle outer side between the center pillar 12 on the left side of the vehicle and the rear seat door 14, and the second antenna When a radio wave is transmitted from 62, the magnetic field propagates outside the vehicle so as to spread around the gap 17 on the vehicle outer side between the center pillar 13 on the right side of the vehicle and the rear seat door 15. Can be secured.

  Also in this embodiment, as in the first embodiment, the low-frequency antennas 61 and 62 are arranged in the vehicle interior, so that a vehicle interior communication area can be secured.

  Therefore, according to the present embodiment, it is possible to secure the vehicle interior communication area and the vehicle exterior communication area in front of the doors on the left and right sides of the vehicle without arranging the low frequency antenna inside the door.

  Also in this embodiment, as in the first embodiment, the low-frequency antennas 61 and 62 are arranged not in the door but in the vehicle interior outside the door, so compared with the case where the antenna is arranged in the door. Thus, it is possible to easily secure the antenna installation location and route the wiring.

  In the present embodiment, the first antenna 61 and the second antenna 62 are each uniaxial antennas, but may be biaxial antennas as in the first embodiment, and at least the coil opening surfaces are the center pillar and the rear seat door. What is necessary is just to have the coil which faces the clearance gap at the vehicle interior side.

(Other embodiments)
(1) In the above-described embodiments, the gaps 16 and 17 on the vehicle interior side between the center pillars 12 and 13 and the rear seat doors 14 and 15 are cited as the clearance on the vehicle interior side between the center pillar and the door. The same effect can be obtained even if the gap described in each embodiment is changed to the gaps 20 and 21 on the vehicle interior side between the center pillars 12 and 13 and the front seat doors 18 and 19 shown in FIG.

  (2) In the first to third embodiments, one low frequency antenna 3 has two coils of the first coil 4 and the second coil 5, but one low frequency antenna 3 is at least the first coil. If there are two types of coils, 4 and the second coil 5, the number of coils may be further increased. The positional relationship between the first coil 4 and the second coil 5 is not limited to the positional relationship shown in FIG.

  (3) In each of the above-described embodiments, the position of the low-frequency antenna in the height direction is set to 4 cm from the floor panel, but may be changed to another height. If the low frequency antenna 3 is installed in the center console as in the first to third embodiments, it can be changed within 0 to 30 cm.

  (4) In each of the above-described embodiments, the vehicle-mounted transceiver 2 has a configuration in which the transmitter, the receiver, and the control device are integrated. However, the transmitter, the receiver, and the control device may be configured separately. good.

  (5) You may combine each above-mentioned embodiment in the range which can be implemented.

DESCRIPTION OF SYMBOLS 1 Portable transmitter / receiver 2 Car-mounted transmitter / receiver 3 Low frequency antenna 4 1st coil 4a Coil opening surface of 1st coil 4b Normal direction of coil opening surface of 1st coil 5 2nd coil 5a Coil opening surface of 2nd coil 5b Normal direction of coil opening surface of second coil 10 Vehicle 12 Center pillar on left side of vehicle 13 Center pillar on right side of vehicle 14 Rear seat door on left side of vehicle 15 Rear seat door on right side of vehicle 31 First virtual straight line 32 Second virtual straight line 61 First antenna (low frequency antenna)
62 Second antenna (low frequency antenna)

Claims (3)

A portable transceiver (1) possessed by the user;
A vehicle-mounted transceiver (2) that is mounted on a vehicle and performs radio communication with radio waves with the portable transceiver (1);
A low-frequency antenna (3) mounted on a vehicle for transmitting low-frequency radio waves,
The on-vehicle transceiver (2) transmits a low-frequency radio wave from the low-frequency antenna (3), and the portable transceiver (1) that receives the low-frequency radio wave transmits the high-frequency radio wave to the on-vehicle radio In the smart entry system that sends to the transceiver (2)
The low frequency antenna (3)
A center portion of the vehicle in the vehicle width direction, a gap formed on the vehicle interior side between the center pillars (12, 13) on the left and right sides of the vehicle and the front seat doors (18, 19), or the centers on the left and right sides of the vehicle It is arranged at a position facing the gap formed on the vehicle interior side between the pillar (12, 13) and the rear seat door (14, 15),
The first coil (4) and the second coil (5) that radiate a magnetic field in different directions, the coil opening surface (4a) of the first coil (4) faces the gap, and the second coil The coil opening surface (5a) of (5) is one antenna configured to face the vehicle longitudinal direction,
The on-vehicle transmitter / receiver (2) has the time from the first and second coils (4, 5) so that the radio waves are radiated from the first and second coils (4, 5) independently. A smart entry system that controls the timing of radio wave transmission.   The low frequency antenna (3) includes a first imaginary straight line (31) extending in the vehicle length direction through the vehicle center in the vehicle width direction, center pillars (12, 13) and front seat doors (18, 19) or between the center pillars (12, 13) on the left and right sides of the vehicle and the rear seat doors (14, 15). The smart entry system according to claim 1, wherein the smart entry system is arranged at a position where the second virtual straight line (32) that is connected intersects. A portable transceiver (1) possessed by the user;
A vehicle-mounted transceiver (2) that is mounted on a vehicle and performs radio communication with radio waves with the portable transceiver (1);
Equipped with a low-frequency antenna (61, 62) mounted on a vehicle for transmitting low-frequency radio waves,
The on-vehicle transceiver (2) transmits a low-frequency radio wave from the low-frequency antenna (61, 62), and the portable transceiver (1) that has received the low-frequency radio wave transmits the high-frequency radio wave to the low-frequency radio wave. In the smart entry system that transmits to the in-vehicle transceiver (2),
As the low frequency antenna,
The vehicle interior side between the center pillar (12) on the left side of the vehicle and the front door (18) or the rear seat door (14), which is located on the vehicle left side of the vehicle width direction center of the vehicle. A first antenna (61) which is disposed at a position facing the gap on the left side of the vehicle, and is configured by a coil having at least a coil opening surface facing the gap on the left side of the vehicle;
The position on the right side of the vehicle in the vehicle interior relative to the center in the vehicle width direction of the vehicle, the vehicle interior side between the center pillar (13) on the right side of the vehicle and the front seat door (19) or the rear seat door (15) And a second antenna (62) that is arranged at a position facing the gap on the right side of the vehicle and that has at least a coil opening surface facing the gap on the right side of the vehicle. .

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