JP2007174237A - Receiver for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely receive radio signal from a portable device, while suppressing the increase in power consumption, as much as possible, in a receiver for vehicle. <P>SOLUTION: The receiver 10 receives a modulated radio signal transmitted from the portable device 2, demodulates the received radio signal by an output circuit 14 and outputs the demodulated signal to an electronic controller 20 for controlling a door lock 22, on the basis of the demodulated signal. In addition, the receiver 10 is provided with a first antenna ANT1 and a second antenna ANT2 having different directivities, a changeover switch 11 for changing over the switch to either the first antenna ANT1 or to the second antenna ANT2 as the antenna for receiving the radio signal, and a detection circuit 15 for detecting the reception state of a receiving antenna changed over as the antenna for receiving the radio signal by the changeover switch 14. The changeover switch 11 changes a switch over to the other antenna, on the basis of the reception state of the receiving antenna detected by the detection circuit 15. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle receiver.

In recent years, the security of vehicles and the improvement of operability when getting on and off have been demanded. When the in-vehicle receiver receives a radio signal transmitted from a portable device, the door lock is not inserted into the keyhole. There is an electronic key system that unlocks and locks (see, for example, Patent Document 1).
JP-A-10-145121

  The conventional vehicle-mounted receiver is provided with a single antenna, and the door lock is unlocked and locked when the antenna receives a radio signal from the portable device. For this reason, if the wireless signal cannot be received from the portable device, the door lock is not unlocked / locked, and the driver must insert the key into the keyhole to unlock / lock. Therefore, it is necessary for the antenna to reliably receive a radio signal from the portable device. However, an antenna with directivity such as a loop antenna used for the antenna creates a region where reception is impossible.

  Thus, it is conceivable to reliably receive a radio signal from the portable device by providing a plurality of antennas having different directivities. However, when a plurality of antennas are provided in the receiver, operating power is supplied to a plurality of signal systems corresponding to the plurality of antennas. For this reason, there is a concern about an increase in power consumption in a reception standby state for a wireless signal from a portable device.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a vehicle receiver that can reliably receive a radio signal from a portable device while suppressing an increase in power consumption as much as possible. There is.

Hereinafter, means for achieving the above-described object and its operation and effects will be described.
The invention according to claim 1 receives the modulated radio signal transmitted from the portable device, demodulates the received radio signal, and demodulates the received radio signal to the control device that controls the control target based on the demodulated signal. In a vehicle receiver that outputs a signal, a plurality of antennas having different directivities, a switching unit that switches to one of the plurality of antennas as an antenna that receives the radio signal, and the radio signal is received by the switching unit Detecting means for detecting a receiving state of the receiving antenna switched as an antenna, and the switching means switches to another antenna based on the receiving state of the receiving antenna detected by the detecting means. It is a summary.

  According to this configuration, since the antenna that receives a radio signal is switched to one of a plurality of antennas having different directivities based on the reception state of the radio signal, the area in which the receiver cannot receive is reduced, and the radio from the portable device is reduced. The signal can be received reliably. In addition, an increase in power consumption can be suppressed as much as possible compared to the case where a large number of antennas are used at one time.

  According to a second aspect of the present invention, in the vehicle receiver according to the first aspect, the switching unit is output from the control device based on a reception state of the receiving antenna detected by the detection unit. The gist is to switch to another antenna by the switching signal.

  According to this configuration, since the control device outputs the switching signal to the switching unit based on the reception state of the receiving antenna detected by the detection unit, the detection unit need only detect the reception state. As a result, it is not necessary to control the switching means on the vehicle receiver side, and unlike the case where a control means for switching control of the switching means is separately provided in the vehicle receiver, the configuration of the vehicle receiver is different. Simplification is achieved.

  Specifically, as described in claim 3, in the vehicle receiver according to claim 1 or 2, the signal strength of the radio signal received by the detection means is detected, and the signal strength is a predetermined threshold value. It is also possible to configure so that the antenna to be received is switched by the switching means when it is less than.

  The gist of the invention according to claim 4 is that, in the vehicle receiver according to any one of claims 1 to 3, the plurality of antennas are provided so as to complement each other's reception area. .

  According to this configuration, a plurality of antennas having different directivities complement each other's reception areas, so that radio signals can be received more reliably.

Hereinafter, an embodiment of a vehicle receiver according to the present invention will be described with reference to FIGS.
FIG. 1 is an electrical configuration diagram of a vehicle receiver that receives a radio signal from a portable device.

  As shown in FIG. 1, the vehicle 1 is provided with a receiver 10. The receiver 10 is connected to an electronic control device 20 that is also provided in the vehicle 1, and a door lock 22 that locks and unlocks the door 21 of the vehicle 1 is connected to the electronic control device 20. The receiver 10 includes a first antenna ANT 1, a second antenna ANT 2, a changeover switch 11, and a receiving circuit 12. The receiving circuit 12 is provided with a receiving unit 13, an output circuit 14, and a detection circuit 15, and operating power is supplied from the electronic control device 20. Here, the changeover switch 11 uses, for example, a mechanical contact or a semiconductor switch. The changeover switch 11 switches between the first antenna ANT1 and the second antenna ANT2 according to a switching signal from the electronic control device 20. The first antenna ANT1 and the second antenna ANT2 are connected to the reception unit 13 of the reception circuit 12 via the changeover switch 11, and the reception unit 13 is connected to the output circuit 14 and the detection circuit 15, respectively. . The output circuit 14 and the detection circuit 15 are each connected to the electronic control unit 20.

  The receiving unit 13 outputs a radio signal from the portable device 2 including the control information received by the first antenna ANT1 or the second antenna ANT2 and the ID information unique to the portable device 2 to the output circuit 14 and the detection circuit 15.

The output circuit 14 demodulates the radio signal output from the receiving unit 13 and outputs the demodulated signal to the electronic control unit 20.
The detection circuit 15 detects the signal strength (electric field strength) of the radio signal output from the receiving unit 13. Then, the detection circuit 15 compares the signal strength of the received radio signal with a preset signal strength determination threshold value. The detection circuit 15 outputs an ON signal to the electronic control device 20 if the received signal strength is greater than or equal to the signal strength determination threshold, and an OFF signal if the received signal strength is less than the signal strength determination threshold. The detection circuit 15 includes an RSSI (Received Signal Strength Indicator) circuit (not shown). This RSSI circuit outputs an RSSI value representing the signal strength (electric field strength) of the received radio signal. In the present embodiment, the detection circuit 15 compares the RSSI value with the signal strength determination threshold value.

  The electronic control device 20 supplies operating power to the receiving circuit 12 intermittently. Further, the electronic control unit 20 determines whether or not to output a switching signal to the changeover switch 11 based on a detection signal (ON signal or OFF signal) from the detection circuit 15. That is, when the ON signal is input from the detection circuit 15, the electronic control unit 20 determines that the reception state is good and does not output the change signal to the changeover switch 11. On the other hand, when an OFF signal is input from the detection circuit 15, the electronic control unit 20 determines that the reception state is not good and outputs a change signal to the changeover switch 11. In addition, the electronic control unit 20 unlocks the door lock 22 when the ID information unique to the portable device included in the demodulated signal of the output circuit 14 matches the vehicle-side ID information stored in advance.

Next, with reference to FIG.2 and FIG.3, the arrangement | positioning and receiving area | region of the antenna of this embodiment are demonstrated.
As shown in FIG. 2, the first antenna ANT1 is a loop antenna formed by winding a conductor wire in a spiral shape a plurality of times. The second antenna ANT2 is a coil antenna formed by winding a conductor wire in a spiral shape a plurality of times. The first antenna ANT1 and the second antenna ANT2 are installed on the substrate 30 so that the winding axis directions of the conductor wires are orthogonal to each other. And the board | substrate 30 with which these 1st antenna ANT1 and 2nd antenna ANT2 are arrange | positioned is installed in the inside of the door 21, for example so that a receiving area may be obtained outside the vehicle 1. FIG.

  FIG. 3 shows a receiving area of the first antenna ANT1 and the second antenna ANT2 on the board 30 installed on the door 21. As shown in FIG. In the figure, the reception area A1 of the first antenna ANT1 is indicated by a broken line, and the reception area A2 of the second antenna ANT2 is indicated by an alternate long and short dash line.

  The shape of the antenna and its arrangement with respect to the vehicle so that the receiving area A1 has a shape in which two semicircular small areas are arranged in the traveling direction of the vehicle 1 on a horizontal plane (a plane parallel to the ground). Is adjusted. In addition, the shape of the antenna, the arrangement with respect to the vehicle, and the like are adjusted so that the reception area A2 has a semicircular shape that overlaps the boundary between the two small areas of the reception area A1 on the horizontal plane. Specifically, at least the reception area A2 is a triangular area A3 surrounded by the outline of two semicircular small areas of the reception area A1 and the common tangent of the two small areas along the traveling direction of the vehicle. The second antenna ANT2 is provided so as to include. That is, the arrangement adjustment of the first antenna ANT1 and the second antenna ANT2 with respect to the board 30 and the arrangement adjustment of the board 30 with respect to the vehicle 1 (door 21) are performed so that the reception area A1 is supplemented by the reception area A2. . As shown in FIG. 3, the reception area A1 is larger than the reception area A2.

  Next, the processing procedure of the electronic control device 20 will be described with reference to the flowchart shown in FIG. 4 and the timing chart shown in FIG. In the reception standby state (normal time) for the radio signal from the portable device 2, the first antenna ANT1 having a reception area larger than the reception area A2 of the second antenna ANT2 is switched.

  In this series of processing, the electronic control unit 20 intermittently supplies operating power to the receiving circuit 12 (step S11). As shown in FIG. 5A (timing t1), when operating power is supplied to the receiving circuit 12, a radio signal from the portable device 2 can be received by the first antenna ANT1. When receiving the radio signal, the output circuit 14 demodulates the received radio signal and outputs the demodulated signal to the electronic control unit 20.

  The detection circuit 15 compares the signal strength of the radio signal received by the first antenna ANT1 with a preset signal strength determination threshold. When the signal strength of the received wireless signal is equal to or greater than the signal strength determination threshold, an ON signal is output to the electronic control device 20. On the other hand, when the signal strength of the received radio signal is less than the signal strength determination threshold, an OFF signal is output to the electronic control unit 20. Then, the electronic control unit 20 determines whether or not the detection signal from the detection circuit 15 is an ON signal (step S12).

  When the ON signal is input from the detection circuit 15 (step S12: YES), the electronic control unit 20 reads the demodulated signal demodulated by the output circuit 14 (step S13). Then, the ID information unique to the portable device 2 included in the demodulated signal is collated with the ID information stored in advance in the electronic control unit 20, and if they match, the door lock 22 is unlocked according to the control information included in the demodulated signal. Locking (locking) is performed (step S14).

  On the other hand, when an OFF signal is input from the detection circuit 15 (step S12: NO), the electronic control unit 20 outputs a switching signal for switching the antenna to the changeover switch 11. When this switching signal is input, the selector switch 11 switches from the first antenna ANT1 to the second antenna ANT2 (step S20).

  As shown in FIG. 5B (timing t2), in the state where the operating power is supplied from the electronic control unit 20 to the receiving circuit 12, the wireless signal from the portable device 2 is received by the second antenna ANT2. It becomes possible. When receiving the radio signal, the output circuit 14 demodulates the received radio signal and outputs the demodulated signal to the electronic control unit 20.

  The detection circuit 15 of the reception circuit 12 compares the signal strength of the radio signal received by the second antenna ANT2 with a preset signal strength determination threshold value. When the signal strength of the received wireless signal is equal to or greater than the signal strength determination threshold, an ON signal is output to the electronic control device 20. When the ON signal is input from the detection circuit 15 (step S22: YES), the electronic control unit 20 proceeds to step S13.

  On the other hand, when the signal strength of the radio signal received by the second antenna ANT <b> 2 is less than the signal strength determination threshold, the detection circuit 15 outputs an OFF signal to the electronic control device 20. When the electronic control device 20 receives an OFF signal from the detection circuit 15 (step S22: NO), the portable device 2 is outside the reception areas A1 and A2 of the first antenna ANT1 and the second antenna ANT2. This process is temporarily terminated. As shown in FIG. 5C (timing t3), the electronic control unit 20 stops the output of the switching signal to the changeover switch 11 and stops the supply of operating power to the receiving circuit 12. Here, the changeover switch 11 switches from the second antenna ANT2 to the first antenna ANT1.

As described above, according to the embodiment described above, the following effects can be obtained.
(1) Since the antenna that receives the radio signal is switched to the first antenna ANT1 or the second antenna ANT2 having different directivities based on the reception state of the radio signal, the area in which the receiver 10 cannot receive is reduced. In addition, the wireless signal from the portable device 2 can be reliably received. In addition, an increase in power consumption can be suppressed as much as possible compared to the case where a large number of antennas are used at one time.

(2) The first antenna ANT1 and the second antenna ANT2 having different directivities complement each other's reception area, so that radio signals can be received more reliably.
(3) Since the electronic control unit 20 outputs the change signal to the changeover switch 11 based on the reception state of the receiving antenna detected by the detection circuit 15, the detection circuit 15 only needs to detect the reception state. As a result, it is not necessary to control the changeover switch 11 on the receiver 10 side, and the configuration of the receiver 10 is simplified unlike the case where a separate control device for controlling the changeover switch 11 is provided in the receiver 10. Is achieved.

  (4) During normal operation, the state is switched to the first antenna ANT1, and the signal strength of the radio signal received by the first antenna ANT1 is less than a preset signal strength determination threshold. In this case, the second antenna ANT2 is switched. Then, by switching in order from the first antenna ANT1 having a larger reception area to the second antenna ANT2 having a smaller reception area, in other words, by switching in order from the antenna having the higher reception possibility, Efficient reception is possible.

Note that the configuration of the above embodiment can be changed as follows.
In the above embodiment, the first antenna ANT1 and the second antenna ANT2 are arranged on the substrate 30 so that the winding axis directions of the conductor wires are perpendicular to each other. What is necessary is just to arrange | position so that it can ensure.

-It is good also considering both the 1st antenna ANT1 and the 2nd antenna ANT2 as a coil antenna.
Both the first antenna ANT1 and the second antenna ANT2 may be loop antennas.

  In the above embodiment, the coil antenna and the loop antenna are used as the antenna. However, an antenna such as a press antenna or a pattern antenna may be used, and a combination of these antennas is also possible.

  In the above embodiment, two antennas are provided, but three or more antennas may be provided. However, when the number of antennas is increased, more space is required for the antennas. Therefore, it is necessary to satisfy both selection of a space-efficient antenna and securing of a reception area. In addition, it is preferable that the directivities of the plurality of antennas are all different and that the reception areas of the plurality of antennas are complemented with each other.

  In the above embodiment, the electronic control unit 20 outputs the switching signal to the changeover switch 11 based on the detection signal output from the detection circuit 15, but the detection circuit 15 indicates the detection result of the received radio signal. Based on this, a changeover signal may be output to the changeover switch 11. As a result, since there is no need to go through the electronic control unit 20, it is possible to make a switching decision only by the receiver 10 and perform the switching.

  In the above embodiment, the substrate 30 is installed inside the door 21, but it may be a place where it is easy to secure a reception area to be obtained, and may be provided, for example, on the front pillar or the rear pillar.

  In the above embodiment, the door lock 22 is unlocked and locked based on the control information of the radio signal from the portable device 2, but the control target is changed according to the function provided in the portable device 2. Also good. For example, the electronic control unit 20 may control the engine, the engine start switch, and the like so that the engine start permission can be given.

The electrical block diagram of the receiver for vehicles. The figure which shows arrangement | positioning of the antenna of the receiver for vehicles. The figure which shows the receiving area of the antenna of the receiver for vehicles. The flowchart which shows the control processing procedure of the receiver for vehicles. (A) (b) (c) The timing chart which shows the control aspect of the receiver for vehicles.

Explanation of symbols

  ANT1 ... first antenna, ANT2 ... second antenna, A1 ... receiving area, A2 ... receiving area, A3 ... area, 1 ... vehicle, 2 ... portable device, 10 ... receiver, 11 ... switch, 12 ... receiving Circuit, 13 ... receiving part, 14 ... output circuit, 15 ... detection circuit, 20 ... electronic control unit, 21 ... door, 22 ... door lock, 30 ... substrate.

Claims (4)

In a vehicle receiver that receives a modulated radio signal transmitted from a portable device, demodulates the received radio signal, and outputs the demodulated signal to a control device that controls a control target based on the demodulated signal ,
A plurality of antennas having different directivities, a switching means for switching to one of the plurality of antennas as an antenna for receiving the radio signal, and a receiving antenna switched as an antenna for receiving the radio signal by the switching means. Detecting means for detecting the reception state,
The vehicle receiver, wherein the switching means switches to another antenna based on the reception state of the receiving antenna detected by the detection means. The vehicle receiver according to claim 1,
The vehicle receiver, wherein the switching unit switches to another antenna by a switching signal output from the control device based on a reception state of the receiving antenna detected by the detection unit. The vehicle receiver according to claim 1 or 2,
The detection means detects the signal strength of the received radio signal,
The vehicle receiver, wherein the switching means switches the receiving antenna when the signal strength is less than a predetermined threshold. In the receiver for vehicles as described in any one of Claims 1-3,
The plurality of antennas are provided so as to complement each other's reception area.

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