JP2018117296A - Communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress power consumption of a battery in a portable device, while sustaining communicable state with the portable device.SOLUTION: In a communication system having a portable device, and a communication device having an output section outputting first and second signals, and communicable with the portable device, the portable device has a receiver sensitivity control section for improving receiver sensitivity when the first signal is received but the second signal is not received, and an intensity measurement section for measuring the signal strength of the first and second signals outputted from the output section, or the signal strength of a third signal, other than the first and second signals, communicated between the portable device and the communication device, when receiver sensitivity has been improved by the receiver sensitivity control section, and transmitting an intensity signal representing the signal strength to the communication device. The communication device includes a receiving section for receiving the intensity signal from the portable device, and a receiver sensitivity change instructing section for instructing the portable device to lower the receiver sensitivity of the portable device, when the intensity signal received by the receiving section goes below a threshold level.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a communication system.

  Conventionally, two-way communication is performed between a portable device owned by a user and a communication device mounted on the vehicle, and the portable device is authenticated in advance by the communication device on the vehicle side, thereby unlocking the user's door. There is a communication system (so-called electronic key system) configured to improve responsiveness to operations and to automatically unlock the vehicle.

  For example, in the following Patent Document 1, in an electronic key system, based on an RSSI value acquired a plurality of times (at least three times) from a key (portable device), the exact position of the key and the key transmits a request signal. A technique is disclosed in which it is determined whether it is moving or stopped in the area, and the periodic transmission of the request signal is stopped when it is determined that the key position is stopped in the transmission area. Yes. According to this technique, it is said that battery consumption of the key can be suppressed.

Japanese Patent Laid-Open No. 2006-124477

  However, although the battery consumption of the key can be suppressed in the above-described prior art, communication with the key cannot be performed because the periodic transmission of the request signal is stopped.

  In order to solve the above-described problems of the related art, an object of the present invention is to suppress power consumption of a battery in a portable device while maintaining a state in which communication with the portable device is possible.

  A communication system according to an embodiment of the present invention is a communication system including a portable device and a communication device having an output unit that outputs a first signal and a second signal, and capable of communicating with the portable device. When the portable device receives the first signal and does not receive the second signal, the reception sensitivity is improved by the reception sensitivity control unit that improves the reception sensitivity and the reception sensitivity control unit. Other than the first signal, the second signal, or the first signal and the second signal output from the output unit, communication is performed between the portable device and the communication device. An intensity measuring unit that measures the signal intensity of the third signal and transmits an intensity signal representing the signal intensity to the communication apparatus, and the communication apparatus receives the intensity signal from the portable device. A receiver, and the portable device received by the receiver. When the intensity signal of the machine is below the threshold value, so as to lower the reception sensitivity of the portable device, and a reception sensitivity changing instruction unit for instructing to the portable device.

  The power consumption of the battery in the portable device can be suppressed while maintaining a state where communication with the portable device is possible.

It is a figure which shows the function structure of the communication system which concerns on embodiment. It is a flowchart which shows the procedure of the process by the vehicle equipment which concerns on embodiment. It is a flowchart which shows the procedure of the process by the portable device which concerns on embodiment. It is a figure which shows an example of the communicable area of the vehicle equipment which concerns on embodiment. It is a figure for demonstrating the specific example of the operation | movement by the communication system which concerns on embodiment.

  Hereinafter, a communication system according to an embodiment of the present invention will be described with reference to the drawings.

(Functional configuration of communication system 10)
FIG. 1 is a diagram illustrating a functional configuration of a communication system 10 according to the embodiment. A communication system 10 illustrated in FIG. 1 includes an in-vehicle device 100 and an electronic key 120. The in-vehicle device 100 is an example of a “communication device” and is mounted on a vehicle 20 such as an automobile (see FIG. 4). The electronic key 120 is an example of a “portable device”. The electronic key 120 is a device for unlocking and locking the vehicle, and is possessed by a user (for example, a driver of the vehicle 20). The communication system 10 performs bidirectional communication between the electronic key 120 and the in-vehicle device 100. When the electronic key 120 is authenticated in the in-vehicle device 100, the lock of the vehicle 20 is automatically unlocked or locked. It is configured as follows. That is, the communication system 10 is a so-called electronic key system.

  As shown in FIG. 1, the in-vehicle device 100 includes an authentication control unit 101, an LF (Low Frequency) transmission unit 102, an RF (Radio Frequency) reception unit 103, a reception sensitivity change instruction unit 104, and a locking control unit 105. Yes.

  The authentication control unit 101 controls the entire authentication process in the in-vehicle device 100. For example, the authentication control unit 101 causes the LF transmission unit 102 to transmit an LF signal (for example, a WAKE signal, an encryption verification signal, a Burst signal, etc.). When the response signal including the authentication information of the electronic key 120 is received by the RF receiving unit 103, the authentication control unit 101 performs the authentication process of the electronic key 120 based on the authentication information.

  The LF transmission unit 102 is an example of an “output unit”. The LF transmission unit 102 transmits an LF signal (for example, a WAKE signal, an encryption verification signal, a Burst signal, etc.) toward the periphery of the in-vehicle device 100 by wireless communication. The LF signal is a signal having a frequency range of 20 kHz to 300 kHz. The WAKE signal is an example of a “first signal”. The WAKE signal is a signal for activating the electronic key 120 that has received this signal. The encryption verification signal is an example of a “second signal”. The encryption verification signal is a signal for requesting the electronic key 120 for authentication information necessary for authentication of the electronic key 120. The Burst signal is an example of a “third signal”. For example, the Burst signal is received by the electronic key 120 and is used for measurement of an RSSI value (Received Signal Strength Indicator) in the electronic key 120. The RSSI value is an example of an “intensity signal”.

  The RF receiving unit 103 is an example of a “receiving unit”. The RF receiver 103 receives an RF signal (for example, an ACK signal, a response signal, etc.) transmitted from the electronic key 120 by wireless communication. The RF signal is a signal having a frequency range of 300 kHz to 3 THz.

  When the response signal including the RSSI value transmitted from the electronic key 120 is received by the RF receiving unit 103, the reception sensitivity change instructing unit 104 becomes a level at which the electronic key 120 cannot receive the WAKE signal based on the RSSI value. Until then, the electronic key 120 is instructed to lower the reception sensitivity of the electronic key 120 by the LF receiver 121. This instruction is realized by the reception sensitivity change instruction unit 104 transmitting an instruction signal for instructing to lower the reception sensitivity to the electronic key 120 via the LF transmission unit 102. Note that the RSSI value of the electronic key 120 is an RSSI value when the electronic key 120 receives a Burst signal transmitted from the in-vehicle device 100, and details will be described later.

  When the authentication control unit 101 authenticates the electronic key 120, the locking control unit 105 locks or unlocks the vehicle 20. For example, the locking control unit 105 unlocks the vehicle 20 when the vehicle 20 is locked, and locks the vehicle 20 when the vehicle 20 is unlocked. Alternatively, the lock control unit 105 locks or unlocks the vehicle 20 in accordance with a lock or unlock instruction from the electronic key 120.

  In the in-vehicle device 100, the authentication control unit 101, the reception sensitivity change instruction unit 104, and the lock control unit 105 are stored in, for example, a memory (for example, ROM (Read Only Memory), RAM (Random Access Memory), etc.). The program is realized by a CPU (Central Processing Unit) executing the program. Further, the LF transmission unit 102 is realized by, for example, an LF transmission circuit and an LF transmission antenna. Further, the RF receiving unit 103 is realized by, for example, an RF receiving circuit and an RF receiving antenna.

  On the other hand, the electronic key 120 includes an LF receiving unit 121, a determination unit 122, a reception sensitivity control unit 123, an RSSI value measurement unit 124, and an RF transmission unit 125.

  The LF receiving unit 121 receives an LF signal (for example, a WAKE signal, an encryption verification signal, a Burst signal, an instruction signal, etc.) transmitted from the in-vehicle device 100.

  The determination unit 122 determines whether or not notification of the RSSI value to the in-vehicle device 100 is necessary based on the reception result of the WAKE signal and the encryption verification signal by the LF reception unit 121. Specifically, the determination unit 122 determines that “the notification of the RSSI value to the in-vehicle device 100 is necessary” when the LF reception unit 121 receives the WAKE signal and fails to receive the encryption verification signal. .

  The reception sensitivity control unit 123 controls the reception sensitivity of the LF reception unit 121. Specifically, the reception sensitivity control unit 123 increases the reception sensitivity of the LF reception unit 121 when the determination unit 122 determines that “the notification of the RSSI value to the in-vehicle device 100 is necessary”. In addition, the reception sensitivity control unit 123 increases the reception sensitivity of the LF reception unit 121 to a level at which the LF reception unit 121 cannot receive the WAKE signal in response to the LF reception unit 121 receiving the instruction signal from the in-vehicle device 100. Lower.

  The RSSI value measurement unit 124 is an example of an “intensity measurement unit”. The RSSI value measurement unit 124 measures the RSSI value of the electronic key 120. Specifically, the RSSI value measurement unit 124 determines that the burst signal transmitted from the in-vehicle device 100 is received by the LF reception unit 121 when the determination unit 122 determines that “notification of the RSSI value to the in-vehicle device 100 is necessary”. The RSSI value when received is measured as the RSSI value of the electronic key 120. For example, the Burst signal is transmitted from the in-vehicle device 100 after the WAKE signal, as will be described later with reference to FIG. Various known methods can be used as the RSSI value measurement method.

  The RF transmission unit 125 transmits an RF signal (for example, an ACK signal, an RSSI value) to the in-vehicle device 100 by wireless communication. Specifically, the RF transmission unit 125 transmits an ACK signal to the in-vehicle device 100 when the LF reception unit 121 successfully receives the WAKE signal. In addition, when the LF reception unit 121 has successfully received the encryption verification signal, the RF transmission unit 125 transmits a response signal including authentication information (for example, an ID code) of the electronic key 120 to the in-vehicle device 100. Further, when the RSSI value measuring unit 124 measures the RSSI value of the electronic key 120, the RF transmitting unit 125 transmits a response signal including the RSSI value to the in-vehicle device 100.

  In the electronic key 120, the determination unit 122, the reception sensitivity control unit 123, and the RSSI value measurement unit 124 are realized by the CPU executing a program stored in a memory (for example, ROM, RAM, etc.), for example. The In addition, the LF receiving unit 121 is realized by, for example, an LF receiving circuit and an LF receiving antenna. Further, the RF transmission unit 125 is realized by, for example, an RF transmission circuit and an RF transmission antenna.

(Processing procedure by the in-vehicle device 100)
FIG. 2 is a flowchart illustrating a processing procedure performed by the in-vehicle device 100 according to the embodiment.

  First, the LF transmission unit 102 transmits a WAKE signal toward the periphery of the vehicle 20 (step S201). Next, the RF receiver 103 determines whether or not an ACK signal transmitted from the electronic key 120 has been received (step S202). In step S202, when it is determined that the ACK signal has not been received (step S202: No), the in-vehicle device 100 executes the processing after step S201 again.

  On the other hand, when it is determined in step S202 that an ACK signal has been received (step S202: Yes), the LF transmission unit 102 transmits an encryption verification signal toward the electronic key 120 (step S203). Then, it is determined whether or not the RF receiving unit 103 has received a response signal transmitted from the electronic key 120 (step S204). In step S204, when it is determined that the response signal has not been received (step S204: No), the in-vehicle device 100 executes the processing after step S201 again.

  On the other hand, if it is determined in step S204 that the response signal has been received (step S204: Yes), the RF receiving unit 103 determines whether or not the authentication information of the electronic key 120 is included in the response signal (step S204). S205).

  If it is determined in step S205 that the authentication information of the electronic key 120 is included (step S205: Yes), the authentication control unit 101 performs the authentication process of the electronic key 120 (step S206). Then, the locking control unit 105 determines whether or not the authentication of the electronic key 120 has succeeded (step S207).

  In step S207, when it is determined that the authentication of the electronic key 120 is successful (step S207: Yes), the locking control unit 105 unlocks or locks the vehicle 20, for example (step S208). And the onboard equipment 100 complete | finishes a series of processes shown in FIG. On the other hand, when it is determined in step S207 that the authentication of the electronic key 120 has not been successful (step S207: No), the in-vehicle device 100 ends the series of processes illustrated in FIG.

  On the other hand, when it is determined in step S205 that the authentication information of the electronic key 120 is not included (step S205: No), the RF receiving unit 103 determines whether the RSSI value of the electronic key 120 is included in the response signal. Is determined (step S209).

  In step S209, when it is determined that the RSSI value of the electronic key 120 is not included (step S209: No), the in-vehicle device 100 executes the processing after step S201 again.

  On the other hand, when it is determined in step S209 that the RSSI value of the electronic key 120 is included (step S209: Yes), the reception sensitivity change instruction unit 104 determines whether the RSSI value is equal to or less than a threshold value. (Step S210).

  When it is determined in step S210 that the RSSI value is not equal to or less than the threshold value (step S210: No), the in-vehicle device 100 ends the series of processes illustrated in FIG. On the other hand, if it is determined in step S210 that the RSSI value is equal to or less than the threshold (step S210: Yes), the reception sensitivity change instruction unit 104 can receive the WAKE signal based on the RSSI value. The electronic key 120 is instructed to lower the reception sensitivity of the LF reception unit 121 until the level disappears (step S211). And the onboard equipment 100 complete | finishes a series of processes shown in FIG.

(Processing procedure using the electronic key 120)
FIG. 3 is a flowchart illustrating a processing procedure performed by the electronic key 120 according to the embodiment.

  First, the LF receiving unit 121 determines whether or not the WAKE signal transmitted from the in-vehicle device 100 has been received (step S301). In step S301, when it is determined that the WAKE signal has not been received (step S301: No), the electronic key 120 executes the processing subsequent to step S301 again.

  On the other hand, when it is determined in step S301 that the WAKE signal has been received (step S301: Yes), the RF transmission unit 125 transmits an ACK signal to the in-vehicle device 100 (step S302).

  Thereafter, the LF receiving unit 121 determines whether or not the encryption verification signal transmitted from the in-vehicle device 100 has been received (step S303). In step S303, when it is determined that the encryption verification signal has been received (step S303: Yes), the RF transmission unit 125 transmits a response signal including the authentication information of the electronic key 120 to the in-vehicle device 100 (step S304). . And the electronic key 120 complete | finishes a series of processes shown in FIG.

  On the other hand, when it is determined in step S303 that the encryption verification signal has not been received (step S303: No), the determination unit 122 determines that “the notification of the RSSI value to the in-vehicle device 100 is necessary” (step S305). ). Then, the reception sensitivity control unit 123 increases the reception sensitivity of the LF reception unit 121 (step S306). In addition, the RSSI value measurement unit 124 measures the RSSI value of the electronic key 120 (step S307). Further, the RF transmission unit 125 transmits a response signal including the RSSI value of the electronic key 120 to the in-vehicle device 100 (step S308).

  Thereafter, the LF receiving unit 121 determines whether or not an instruction signal is received from the in-vehicle device 100 (step S309). In step S309, when it is determined that the instruction signal has not been received (step S309: No), the electronic key 120 executes the processing from step S307 onward again.

  On the other hand, if it is determined in step S309 that the instruction signal has been received (step S309: Yes), the reception sensitivity control unit 123 lowers the reception sensitivity of the LF reception unit 121 to a level at which the WAKE signal cannot be received (step S309). S310). And the electronic key 120 complete | finishes a series of processes shown in FIG.

  In the example of FIG. 3, when the encryption verification signal cannot be received even once, it is determined that “the notification of the RSSI value to the in-vehicle device 100 is necessary”. However, for example, the WAKE signal is If an event that the signal can be received and the encryption verification signal cannot be received continuously occurs for a certain number of times, it may be determined that “the notification of the RSSI value to the in-vehicle device 100 is necessary”. The certain number of times may be about 2 or 3 times, for example.

(Example of communicable area of in-vehicle device 100)
FIG. 4 is a diagram illustrating an example of a communicable area of the in-vehicle device 100 according to the embodiment. In the example shown in FIG. 4, the WAKE signal receivable area A1 transmitted by the LF transmitter 102 of the vehicle-mounted device 100 on both the left and right sides of the vehicle 20 (where the upper side in the figure is the front of the vehicle 20). And a receivable area A2 of the encryption verification signal transmitted by the LF transmitter 102 of the in-vehicle device 100. The receivable area A1 includes the receivable area A2. That is, in the receivable area A2, the electronic key 120 can receive both the WAKE signal and the encryption verification signal.

  As shown in FIG. 4, the area A2 where the encryption verification signal can be received is narrower than the area A1 where the WAKE signal can be received. This is because the electronic key 120 is set so that the reception sensitivity of the encryption verification signal is lower than the reception sensitivity of the WAKE signal, as in a general portable device. For this reason, as shown in FIG. 4, when the electronic key 120 exists at the position P1 outside the receivable area A2 and within the receivable area A1, the electronic key 120 can receive the WAKE signal. The cipher verification signal cannot be received.

  Therefore, in such a case, in the communication system 10 of the present embodiment, the reception sensitivity of the electronic key 120 is lowered based on the RSSI value of the electronic key 120 so that the electronic key 120 cannot receive the WAKE signal at the position P1. I am doing so. As a result, the communication system 10 can prevent the electronic key 120 from receiving the WAKE signal many times and repeatedly performing the activation process.

  In the communication system 10 of this embodiment, when a plurality of electronic keys are present in the communicable area of the in-vehicle device 100, the reception sensitivity of each electronic key can be individually controlled. For example, in the example of FIG. 4, when there is an electronic key other than the electronic key 120 outside the receivable area A <b> 2 and within the receivable area A <b> 1, the communication system 10 is similar to the electronic key 120. The reception sensitivity of the electronic key can be lowered. In the example of FIG. 4, when there is an electronic key other than the electronic key 120 in the receivable area A2, the communication system 10 keeps the reception sensitivity of the other electronic key as it is, and only the electronic key 120 is used. Reception sensitivity can be lowered.

(Specific example of operation by communication system 10)
FIG. 5 is a diagram for explaining a specific example of the operation of the communication system 10 according to the embodiment. The first row in FIG. 5 shows the output timing of the LF signal by the in-vehicle device 100. The second row in FIG. 5 shows the output timing of the RF signal from the electronic key 120. The third row in FIG. 5 shows the reception sensitivity of the electronic key 120.

  As shown in FIG. 5 (first stage), the in-vehicle device 100 repeatedly transmits a WAKE signal and a Burst signal at regular intervals. When entering the receivable area A1, the electronic key 120 receives a WAKE signal and transmits an ACK signal to the in-vehicle device 100 (timing t1 in the figure). Thereafter, the in-vehicle device 100 transmits an encryption verification signal toward the electronic key 120 (timing t2 in the figure). Here, as illustrated in FIG. 4, when the electronic key 120 exists outside the area A2 where the encryption verification signal can be received, the electronic key 120 cannot receive the encryption verification signal (timing t3 in the figure). .

  In such a case, the electronic key 120 increases its own reception sensitivity from “normal sensitivity” to “high sensitivity” (timing t4 in the figure). Then, the electronic key 120 measures its RSSI value from the Burst signal transmitted from the in-vehicle device 100. And the electronic key 120 transmits the response signal containing this RSSI value to the vehicle equipment 100 (timing t5 in the figure).

  Upon receiving this response signal, the in-vehicle device 100 sends an instruction signal for reducing the reception sensitivity to a level at which the WAKE signal cannot be received based on the RSSI value of the electronic key 120 included in the response signal. 120 (timing t6 in the figure). Upon receiving this instruction signal, the electronic key 120 lowers its own reception sensitivity from “high sensitivity” to “low sensitivity” (timing t7 in the figure). “Low sensitivity” is a lower reception sensitivity than “normal sensitivity”. Thereby, the reception sensitivity of the electronic key 120 becomes a level at which the WAKE signal cannot be received. Therefore, the electronic key 120 can avoid a situation in which only the WAKE signal is repeatedly received.

  As described above, in the communication system 10 according to the present embodiment, when the electronic key 120 receives the WAKE signal and fails to receive the encryption verification signal, based on the RSSI measurement value of the electronic key 120, The reception sensitivity of the electronic key 120 is lowered. For this reason, according to the communication system 10 according to the present embodiment, the electronic key 120 repeatedly performs the activation process outside the area where the encryption verification signal can be received, and consumes its own power wastefully. Can be suppressed.

  Note that the communication system 10 according to the present embodiment stops the periodic transmission of the request signal when it is determined that the key position is stopped in the transmission area, as in the conventional electronic key system. Don't do that. That is, the communication system 10 does not stop the transmission of the WAKE signal and the encryption verification signal, and continues to maintain a state in which communication with the electronic key 120 is possible even after the reception sensitivity of the electronic key 120 is reduced. can do.

  Further, the communication system 10 according to the present embodiment reduces the reception sensitivity of the electronic key 120 to a level at which the WAKE signal cannot be received. For this reason, according to the communication system 10 which concerns on this embodiment, the situation where the electronic key 120 repeatedly performs a starting process can be avoided more reliably.

  In the present embodiment, an example in which the present invention is applied to an electronic key system for a vehicle has been described. However, the present invention transmits and receives at least a first signal and a second signal between at least a communication device and a portable device. Any communication system can be applied as long as it is a communication system. For example, the present invention can be applied to a home electronic key system. In addition, for example, the present invention can be applied to a communication system configured to be able to provide some information from a communication device to a portable device.

  In the present embodiment, the reception sensitivity of the electronic key 120 is lowered to the target value (that is, the level at which the WAKE signal cannot be received) at a time, but the present invention is not limited to this. For example, the reception sensitivity of the electronic key 120 may be lowered stepwise to the target value.

  In the present embodiment, the electronic key 120 measures the RSSI value using the Burst signal transmitted from the in-vehicle device 100, but the present invention is not limited to this. For example, the electronic key 120 may measure the RSSI value using the WAKE signal or the encryption verification signal transmitted from the in-vehicle device 100.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to these embodiments, and various modifications or changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

DESCRIPTION OF SYMBOLS 10 Communication system 20 Vehicle 100 Vehicle-mounted apparatus (communication apparatus)
101 Authentication control unit 102 LF transmission unit (output unit)
103 RF receiver (receiver)
104 Reception Sensitivity Change Instruction Unit 105 Locking Control Unit 120 Electronic Key (Portable Machine)
121 LF receiver (receiver)
122 determination unit 123 reception sensitivity control unit 124 RSSI value measurement unit (strength measurement unit)
125 RF transmitter

Claims (1)

A communication system comprising a portable device and a communication device having an output unit for outputting the first signal and the second signal and capable of communicating with the portable device,
The portable device is
A reception sensitivity control unit for improving reception sensitivity when receiving the first signal and not receiving the second signal;
When the reception sensitivity is improved by the reception sensitivity control unit, the first signal output from the output unit, the second signal, or the first signal and the second signal other than the first signal. An intensity measuring unit that measures the signal intensity of a third signal communicated between the portable device and the communication apparatus, and transmits an intensity signal representing the signal intensity to the communication apparatus;
The communication device
A receiving unit for receiving the intensity signal from the portable device;
A reception sensitivity change instruction unit that instructs the portable device to reduce the reception sensitivity of the portable device when an intensity signal of the portable device received by the receiving unit is equal to or lower than a threshold value. Communications system.

Images