JP4341151B2 - In-vehicle wireless communication system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an in-vehicle wireless communication system that performs wireless communication in a vehicle.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an automobile telephone is composed of a telephone set that is arranged on a center console in a vehicle compartment via a cradle (station) and a wireless device that is arranged in a trunk room. In this device, the telephone is electrically connected to the cradle through electrical wiring, and the cradle is electrically connected to the wireless communication device through electrical wiring. The wireless communication device is connected to an antenna disposed outside the passenger compartment by electric wiring and performs wireless communication with the communication network side through the antenna.
[0003]
Here, as a wireless communication device, a space in the vehicle compartment can be ensured by disposing it in the trunk room. In addition, when the antenna is arranged outside the passenger compartment and in the vicinity of the trunk room, the distance between the antenna and the wireless communication device can be shortened, so that the power loss between the wireless communication device and the antenna is reduced. be able to.
[0004]
[Problems to be solved by the invention]
However, in an automobile telephone, as described above, since the telephone is connected to the wireless communication device via the cradle by electric wiring, it is difficult for the telephone to move freely in the vehicle interior. In addition, a long electrical wiring is required for electrical connection between the cradle and the wireless communication device. By the way, in recent years, in the information communication field, rapid development has been achieved, and development of wireless communication devices using a high frequency (for example, 2.4 GHz) such as Bluetooth has been actively performed. Therefore, the present inventors have examined performing wireless communication using high frequency instead of wired communication between a telephone device of a car phone and a wireless communication device.
[0005]
According to studies by the present inventors, when wireless communication is performed between a wireless communication device in a trunk room and a telephone device in a vehicle compartment, the telephone device cannot obtain the reception sensitivity necessary for wireless communication. I found out that This is because the maximum value of output (aerial power) is restricted by law (Radio Law) for the above wireless communication, and there is a shield (for example, a fuel tank) between the trunk room and the passenger compartment. This is because the shielding object reflects the radio wave output from the wireless communication device in the trunk room to the tail lamp side (the vehicle rear side).
[0006]
Here, an opening is formed in the outer plate on the rear side of the vehicle, and this opening is for passing electric wiring (feeding wiring and signal wiring) from the inside of the trunk room to the tail lamp. Therefore, although the opening has a small size of several centimeters (for example, 15 cm to 20 cm), a frequency exceeding 1 GHz is used for wireless communication between the wireless communication device in the trunk room and the telephone in the vehicle interior. It was found that the wavelength of the radio wave was short, and the radio wave was emitted outside the car through an opening of several centimeters square. For this reason, there is a problem that a car phone is temporarily disconnected when the reception sensitivity falls below a predetermined value during a call.
[0007]
SUMMARY OF THE INVENTION In view of the above, the present invention provides an in-vehicle wireless communication system that performs wireless communication between a wireless communication device in a trunk room and a wireless communication device in a vehicle interior, and that improves reception sensitivity in the vehicle interior. The purpose is to do.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, in the first aspect of the present invention, a wireless device is disposed in a trunk room (100) of a vehicle and transmits electromagnetic waves to a wireless communication device (4) in the vehicle cabin as a medium. An electromagnetic wave reflecting member (15) that reflects the electromagnetic wave that has reached the opening (12) for passing the communication device (2) and the electric wiring (13) from the inside of the trunk room to the lamp unit (10) outside the vehicle compartment to the vehicle interior side. ). Thus, since the electromagnetic wave which reached the opening by the electromagnetic wave reflecting member is reflected to the vehicle interior side, the reception sensitivity in the wireless communication device in the vehicle interior can be improved. Specifically, as in the invention described in claim 2, the electromagnetic wave reflecting member may be formed so as to cover the opening from the inside of the trunk room.
[0009]
In the invention according to claim 3, the wireless communication device (2) disposed in the trunk room (100) of the vehicle and transmitting electromagnetic waves as a medium to the wireless communication device (4) in the vehicle interior, and the vehicle interior from the trunk room A lamp unit (10) disposed on the outer side of the passenger compartment facing the opening (12) formed on the outer side, the lamp unit being formed to be exposed to the light emitting part (10b) and outside the passenger compartment. And a light transmission part (10c) that transmits the light of the light emitting part to the outside of the vehicle interior, and the light transmission part reflects the electromagnetic wave that has reached the opening (12) to the vehicle interior side. It is characterized by comprising a reflective material . Thus, since the electromagnetic waves that have reached the opening by the lamp unit are reflected toward the vehicle interior side, the reception sensitivity of the wireless communication device in the vehicle interior can be improved.
[0010]
Incidentally, the reference numerals in parentheses of each means described above are an example showing the correspondence with the specific means described in the embodiments described later.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
1 to 5 show an embodiment in which an in-vehicle wireless communication system according to the present invention is applied to a car phone. FIG. 1 is a perspective view of a vehicle (automobile) in which an automobile telephone is arranged, and FIG. 2 is a top view of the vehicle.
[0012]
In FIG. 1, 1 is a wireless storage, which is arranged on the left side of the vehicle in the trunk room 100 of the vehicle, and 2 is a wireless communication device, which performs wireless communication with a communication network (base station) through an external antenna (not shown). On the other hand, wireless communication is performed with the telephone terminal 4 in the vehicle interior 110 through the internal antenna 3. Further, as a wireless communication method between the wireless communication device 2 and the telephone terminal 4, Bluetooth using a 2.4 GHz band radio wave is adopted. As a result, the telephone terminal 4 functions as a Bluetooth terminal.
[0013]
The transmission power of the wireless communication apparatus 2 is 0 dBm (determined by the Bluetooth standard), and an omnidirectional dipole antenna is adopted as the internal antenna 3. Further, the wireless storage 1 is fixed to a mounting portion at the bottom in the trunk room 100.
[0014]
As shown in FIG. 2, a rear upper tray 7 is arranged between the rear seat and the rear glass 120 in the vehicle interior 110, and the rear upper tray 7 has dimensions of several centimeters (for example, 15 cm to 20 cm). Speaker mounting holes 8 are formed. Since the speaker mounting hole 8 penetrates between the trunk room 100 and the vehicle interior 110, it functions as a radio wave propagation path between the wireless communication device 2 and the telephone terminal 4. That is, the radio wave output from the internal antenna 3 travels from the trunk room 100 to the vehicle interior 110 through the speaker mounting hole 8. A power distribution diagram in the passenger compartment in this case is shown in FIG.
[0015]
Here, whether or not the telephone device 4 functions as a Bluetooth terminal is determined by the performance of the radio unit, but the reception sensitivity is determined to be −70 dBm or more by the Bluetooth standard. : -70 dBm or less, the telephone terminal 4 cannot receive radio waves (information) as a Bluetooth terminal. In FIG. 3, the hatched portion (black portion) indicates a portion with a reception sensitivity of −70 dBm or more, and the white portion indicates a portion with a reception sensitivity of less than −70 dBm. As can be seen from FIG. 3, it can be seen that there is a portion with a reception sensitivity of less than −70 dBm. That is, it can be seen that there is a portion in the vehicle interior 110 where the telephone terminal 4 cannot function as a Bluetooth terminal.
[0016]
By the way, in the trunk room 100, as shown in FIG. In the example shown in FIG. 1, a fuel tank (gasoline tank) is arranged as the radio wave shield 5. For this reason, when the radio wave output from the internal antenna 3 reaches the radio wave shield 5, the radio wave shield 5 reflects the radio wave shield 5 toward the tail lamp unit 10 (rear side of the vehicle) as indicated by an arrow 130.
[0017]
Here, as shown in FIG. 4, both hole portions (for example, 15 cm to 20 cm square) 12 are formed outward from the inside of the trunk room 100 on the rear side of the vehicle body. The cable (feeding line, signal line) 13 electrically connected to the tail lamp unit 10 is provided to pass through the trunk room 100. In the example shown in FIG. 4, both the hole portions 12 are formed in the luggage door 11 formed so as to cover the trunk room 100.
[0018]
The tail lamp portions 10 are each formed in a substantially rectangular shape, and are arranged on the rear side with respect to the hole portion 12. The tail lamp portion 10 is composed of a case 10a, a lamp body 10b, and a cover portion 10c. The case 10a is combined with the cover portion 10c to form a substantially rectangular shape and has a hollow portion (hereinafter referred to as an internal hollow portion) inside. Form. The lamp body 10b is disposed in the inner hollow portion of the case 10a and the cover portion 10c, and is positioned toward the rear side. The cover portion 10c is made of glass (or transmissive resin) and is formed so as to cover the lamp body 10b. The cover portion 10c is exposed to the outside and transmits light emitted from the lamp body 10b.
[0019]
Here, the tail lamp unit 10 does not have the function of electromagnetically blocking together with the two hole portions 12, and as described above, the wireless communication between the wireless communication device 2 and the telephone terminal 4 is 2.4. Since the radio wave of GHz band is used, the wavelength of the radio wave is short. For this reason, as described above, most of the radio waves reflected to the tail lamp unit 10 side by the radio wave shield 5 are emitted from the both hole parts 12 (for example, 15 cm to 20 cm square), so the telephone in the passenger compartment 110 This interferes with radio wave radiation to the device terminal 4.
[0020]
Therefore, as shown in FIG. 5, when both metal plates (aluminum foil, aluminum plate) 15 are arranged so as to cover both hole portions 12 from the inside of the trunk room 100, the tail lamp portion 10 side is provided by the radio wave shield 5 as described above. The radio waves reflected by the can be reflected by the two metal plates 15 toward the vehicle interior 120 side. A power distribution diagram in the passenger compartment in this case is shown in FIG. In FIG. 5, as in FIG. 3, the hatched portion (black portion) indicates a portion with a reception sensitivity of −70 dBm or more, and the white portion indicates a portion with a reception sensitivity of less than −70 dBm. According to FIG. 5, it can be seen that the portion of reception sensitivity of −70 dBm or more is increased as compared with FIG. 3. Therefore, the reception sensitivity in the passenger compartment 110 can be improved in the automobile telephone that performs wireless communication between the wireless communication device 1 in the trunk room 100 and the telephone terminal 4 in the passenger compartment. In addition, since radio waves entering from the outside through both hole portions 12 are blocked by both metal plates 15, interference can be prevented by wireless communication between the wireless communication device 1 and the telephone terminal 4. In addition to this, the radio waves from the telephone terminal 4 are reflected by the two metal plates 15, so that the reception sensitivity in the wireless communication device 1 can be improved.
[0021]
Furthermore, in carrying out the present invention, a radio wave reflecting glass may be employed as the cover portion 10c instead of the two metal plates 15. In this case, the same effect as the above embodiment can be obtained.
[0022]
In the above embodiment, as an example of a vehicle (automobile), a trunk room formed independently of a passenger compartment has been described. However, the present invention is not limited to this, and a trunk-through type that eliminates the boundary between the trunk room and the passenger compartment. A thing may be adopted. In this case, the trunk room corresponds to the space behind the seat in the vehicle 110. According to this, the wireless communication device 1 is arranged in the space behind the seat in the vehicle 110.
[0023]
Furthermore, in carrying out the present invention, the lamp is not limited to the tail lamp unit 10, but may be applied to a hazard lamp, a direction indicator lamp, or the like.
[0024]
Furthermore, in the above-described embodiment, the example in which Bluetooth is adopted as the communication method between the wireless communication device 1 and the telephone terminal 4 in the trunk 100 has been described. However, the present invention is not limited to this, and various wireless methods may be adopted. Good.
[0025]
In the above embodiment, an example in which a car phone is adopted as the in-vehicle communication terminal has been described. However, the present invention is not limited to this and may be applied to car navigation.
[0026]
For example, as a car navigation system, the wireless communication device 1 in the trunk room 100 and a display panel arranged on the instrument panel are adopted, and this display panel functions as a Bluetooth terminal. You may make it perform packet communication of image data (map data) between terminals. In this case, when the reception sensitivity is low at the Bluetooth terminal of the display panel, packet communication is repeated. Therefore, the display panel causes a problem that the same map image is repeatedly displayed. However, if the metal plate 15 is adopted as in the above embodiment, the above-described problems can be solved.
[0027]
In addition, the hands-free set may function as a Bluetooth terminal, the hands-free set may function as a Bluetooth terminal, or a personal computer or an information terminal may function as a Bluetooth terminal.
[Brief description of the drawings]
FIG. 1 is a perspective view of a vehicle showing an embodiment of the present invention.
FIG. 2 is a top view of the vehicle shown in FIG.
FIG. 3 is a diagram showing a power distribution in the passenger compartment.
FIG. 4 is a diagram showing a tail lamp portion shown in FIG.
FIG. 5 is a diagram showing a tail lamp unit shown in FIG. 1;
FIG. 6 is a diagram showing a power distribution in the passenger compartment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Tail lamp part, 12 ... Opening part, 15 ... Metal plate, 13 ... Cable.

Claims (3)

A wireless communication device (2) disposed in the trunk room (100) of the vehicle and transmitting electromagnetic waves as a medium to the wireless communication device (4) in the passenger compartment;
An electromagnetic wave reflecting member (15) for reflecting the electromagnetic wave that has reached the opening (12) for passing the electric wiring (13) from the inside of the trunk room to the lamp unit (10) outside the vehicle compartment to the vehicle interior side; An in-vehicle wireless communication system comprising:   The in-vehicle wireless communication system according to claim 1, wherein the electromagnetic wave reflecting member is formed so as to cover the opening from the inside of the trunk room. A wireless communication device (2) disposed in the trunk room (100) of the vehicle and transmitting electromagnetic waves as a medium to the wireless communication device (4) in the passenger compartment;
A lamp unit (10) disposed on the outside of the passenger compartment facing the opening (12) formed on the outside of the passenger compartment from within the trunk room;
The lamp unit includes a light emitting part (10b) and a light transmitting part (10c) that is formed so as to be exposed to the outside of the passenger compartment and transmits the light of the light emitting part to the outside of the passenger compartment.
The in-vehicle wireless communication system , wherein the light transmission part is made of an electromagnetic wave reflecting material that reflects the electromagnetic wave that has reached the opening (12) to the vehicle interior side .

Images