Security system, wire harness, connector, and on-board device

Abstract

This security system is used in a system in which communication between a first communication unit and a second communication unit is established by a communication line. The security system comprises: a signal superposition circuit that superposes a signal having prescribed frequency characteristics with respect to a communication line; and a filter unit that is provided on a transmission line path from a position at which the signal is superposed by the signal superposition circuit to where the second communication unit receives a communication signal transmitted by the first communication unit, and filters a superposition signal that is the signal that has been superposed.

Description

Security system, wire harness, connector, and in-vehicle device

[0001] This disclosure relates to a security system, a wire harness, a connector, and an in-vehicle device. This application claims priority to Japanese Patent Application No. 2023-105865, filed on June 28, 2023, and incorporates by reference all of the contents of said Japanese application.

[0002] Vehicles are equipped with various on-board devices. These devices include various ECUs (Electronic Control Units) that control functions necessary for the vehicle, such as steering and braking. These ECUs are connected to each other to form a network. Each ECU communicates with each other via this network to realize basic vehicle functions, such as "driving," "turning," and "stopping." Wiring harnesses are usually used to connect the on-board devices.

[0003] Such in-vehicle devices require technology to prevent hacking or data tampering of the in-vehicle devices (ECUs).Patent Document 1, listed below, proposes a connector system for preventing communication between a wire harness and unintended devices.

[0004] The connector system described in Patent Document 1 includes a first connector and a second connector connected thereto. The second connector includes a processing unit that creates verification information and transmits it to the first connector. The first connector includes a verification unit that verifies the second connector based on the verification information received from the second connector. The verification unit determines that verification has failed if it is unable to receive the verification information. The first connector further includes a switch that, when connected to the second connector, switches between electrically connecting the transmission line in the first connector and the transmission line in the second connector, and a control unit that controls the switch based on the verification results of the verification unit.

[0005] If the second connector is an unauthorized connector, the verification unit of the first connector determines that the verification has failed. The control unit of the first connector maintains the switch in the off state. This interrupts the electrical connection between the transmission line of the first connector and the transmission line of the second connector. This prevents communication between the wire harness and unintended devices, ensuring the security of communication between devices.

[0006] International Publication No. 2019 / 187349

[0007] A security system according to one aspect of the present disclosure is a security system used in a system that connects communication between a first communication unit and a second communication unit via a communication line, and includes a signal superposition circuit that superimposes a signal having a predetermined frequency characteristic onto the communication line, and a filter unit that is provided on a transmission line from a position where the signal is superimposed by the signal superposition circuit to a position where the communication signal transmitted by the first communication unit is received by the second communication unit, and that filters the superimposed signal.

[0008] The present disclosure can be realized not only as a security system, wire harness, connector, or in-vehicle device that includes such a characteristic configuration, but also as other systems or devices that include a security system, wire harness, connector, or in-vehicle device.

[0009] FIG. 1 is a diagram for explaining a security system according to a first embodiment. FIG. 2 is a diagram showing an example of the spectrum of a signal flowing through a communication line. FIG. 3 is a diagram showing an example of the spectrum of a signal flowing through a communication line. FIG. 4 is a diagram showing an example of the configuration of the security system shown in FIG. 1. FIG. 5 is a diagram showing an example of the configuration of a connector of a wire harness shown in FIG. 5. FIG. 6 is a diagram showing an example of a filter unit (open stub). FIG. 7 is a diagram showing an example of the configuration of a wire harness according to a second embodiment. FIG. 8 is a diagram for explaining a security system according to a third embodiment. FIG. 9 is a diagram showing an example of the configuration of the security system shown in FIG. 1. FIG. 10 is a block diagram showing an example of the configuration of a first in-vehicle device shown in FIG. 9. FIG. 11 is a block diagram showing an example of the functional configuration of a control unit shown in FIG. 10. FIG. 12 is a block diagram showing an example of the configuration of a second in-vehicle device shown in FIG. 9. FIG. 13 is a block diagram showing an example of the functional configuration of a control unit shown in FIG. 12.

[0010] The connector system described in Patent Document 1 is an excellent system in terms of ensuring security. However, because the processing unit, verification unit, and control unit are realized by electronic devices, and the electronic devices and switches are built into the connector, it is difficult to simplify the configuration. As a result, manufacturing costs tend to be high.

[0011] The present disclosure has been made to solve such problems, and one object of the present disclosure is to provide a security system, a wire harness, a connector, and an on-board device that can improve communication security with a simpler configuration.

[0012] Effect of the Present Disclosure According to the present disclosure, it is possible to provide a security system, a wire harness, a connector, and an in-vehicle device that can improve communication security with a simpler configuration.

[0013] [Description of Embodiments of the Present Disclosure] Preferred embodiments of the present disclosure will be listed and described below. At least some of the embodiments described below may be combined in any combination.

[0014] (1) A security system according to a first aspect of the present disclosure is a security system used in a system that connects communication between a first communication unit and a second communication unit via a communication line, and includes a signal superposition circuit that superimposes a signal having a predetermined frequency characteristic onto the communication line, and a filter unit that is provided on a transmission line from a position where the signal is superimposed by the signal superposition circuit to a position where the communication signal transmitted by the first communication unit is received by the second communication unit, and that filters the superimposed signal.

[0015] The signal superposition circuit superimposes a signal having a predetermined frequency characteristic onto the communication line. The superimposed signal superimposed on the communication line is removed by the filter unit. Therefore, even if the superimposed signal is transmitted along with the communication signal transmitted from the first communication unit, the second communication unit can receive the communication signal from which the superimposed signal has been removed. Therefore, communication between the first communication unit and the second communication unit is performed normally. On the other hand, for example, if an unauthorized device is connected to the first communication unit, the superimposed signal is not removed because it does not go through the filter unit. Therefore, if an unauthorized device is connected to the first communication unit, the superimposed signal can make communication with the first communication unit difficult. In this way, this security system can improve communication security with a simpler configuration.

[0016] (2) In the above (1), the signal superimposing circuit may be provided on the first electrical board on which the first communication unit is mounted. This allows for an easier and simpler configuration.

[0017] (3) In the above (1) or (2), the filter unit may include an open stub filter capable of removing a superimposed signal. This allows for an easier and simpler configuration.

[0018] (4) In any of the above (1) to (3), the communication between the first communication unit and the second communication unit may be connected by a wire harness, the wire harness may include a communication line and a connector connected to an end of the communication line, and the filter unit may be provided on the communication line or the connector. This also makes it possible to easily achieve a simpler configuration.

[0019] (5) In the above (4), the wire harness may further include a sheet-like holding member for holding the communication wires. This makes it possible to obtain a flat wire harness that can improve communication security with a simpler configuration.

[0020] (6) In any of the above (1) to (3), the filter unit may be provided on the second electrical board on which the second communication unit is mounted or on a connector provided on the second electrical board, which also facilitates a simpler configuration.

[0021] (7) A security system according to a second aspect of the present disclosure is a security system used in a system that connects communication between a first communication unit and a second communication unit via a communication line, and includes a signal superposition circuit that is provided on a first electrical board on which the first communication unit is mounted and that superimposes a signal having a predetermined frequency characteristic onto the communication line, and a signal detection circuit that is provided on a second electrical board on which the second communication unit is mounted and that detects the superimposed signal.

[0022] The signal superposition circuit superposes a signal having a predetermined frequency characteristic onto the communication line. The superposed signal, which is the signal superposed onto the communication line, is detected by a signal detection circuit on the second communication unit side. Therefore, the superposed signal can be used as an authentication signal in communication between the first communication unit and the second communication unit. Therefore, this security system can also improve communication security with a simpler configuration.

[0023] (8) In the above (7), the signal superposition circuit may add a superposition signal to the communication line at a predetermined timing, and the second communication unit may transmit a reply signal to the first communication unit in response to the detection of the superposition signal when the signal detection circuit detects the superposition signal. For example, if an unauthorized device is connected to the first communication unit, the first communication unit may not receive the reply signal. This allows the first communication unit to recognize that an unauthorized device has been connected.

[0024] (9) In any of the above (1) to (8), the signal superposition circuit may be configured to superpose an out-of-band signal used for communication onto the communication line, thereby improving communication security while reducing the impact on communication between the first communication unit and the second communication unit.

[0025] (10) A wire harness according to a third aspect of the present disclosure is a wire harness that connects communication between a first communication unit and a second communication unit, and includes a communication line, a connector connected to an end of the communication line, and a filter unit that is provided on the communication line or the connector and filters a superimposed signal superimposed on the communication line.

[0026] If an unauthorized device is connected to the first communication unit, removing the wire harness from the first communication unit will cause the unauthorized device to communicate with the first communication unit without going through the filter unit. In this case, the superimposed signal on the communication line will not be removed. Therefore, even if an unauthorized device is connected to the first communication unit, it will be difficult for the unauthorized device to communicate with the first communication unit. Therefore, this wire harness can also improve communication security with a simpler configuration.

[0027] (11) In the above (10), the filter unit may include an open stub filter capable of removing a superimposed signal. This allows for an easier and simpler configuration.

[0028] (12) In the above (10) or (11), the wire harness may further include a sheet-like holding member for holding the communication wires. This makes it possible to obtain a flat wire harness that can improve communication security with a simpler configuration.

[0029] (13) A connector according to a fourth aspect of the present disclosure is a connector used in a system that connects communication between a first communication unit and a second communication unit via a communication line, and includes a housing and a filter unit provided within the housing that filters a superimposed signal superimposed on the communication line.

[0030] By using this connector, communication security can be improved with a simpler configuration.

[0031] (14) A fifth aspect of the present disclosure provides an in-vehicle device that communicates with other in-vehicle devices via a communication line, and includes a communication unit and a signal superposition circuit that superposes a signal having a predetermined frequency characteristic onto the communication line.

[0032] According to this in-vehicle device, communication security can be improved with a simpler configuration.

[0033] (15) In the above (14), the signal superposition circuit may further include a communication restriction unit that superimposes a signal as a superposition signal on the communication line at a predetermined timing, and restricts communication if a reply signal responding to the detection of the superposition signal is not transmitted from another in-vehicle device after the superposition signal has been added. This allows for improved communication security with a simpler configuration.

[0034] (16) A sixth aspect of the present disclosure provides an in-vehicle device that communicates with other in-vehicle devices via a communication line, and includes a communication unit and a signal detection circuit that detects a superimposed signal superimposed on the communication line by the other in-vehicle device. When the signal detection circuit detects the superimposed signal, the communication unit transmits a reply signal to the other in-vehicle device in response to the detection of the superimposed signal.

[0035] This in-vehicle device also improves communication security with a simpler configuration.

[0036] [Details of the Embodiments of the Present Disclosure] Specific examples of a security system, a wire harness, a connector, or an in-vehicle device according to the embodiments of the present disclosure will be described below with reference to the drawings. Note that in the following embodiments, identical components are assigned the same reference numerals. Their functions and names are also identical. Therefore, detailed description thereof will not be repeated.

[0037] (First embodiment) [Overall configuration] Referring to Fig. 1, a security system 50 according to this embodiment includes a signal superposition circuit 100 that superposes a signal component having a known frequency characteristic onto a communication line 20 (transmission line), and a filter unit 200 that removes the signal component superposed on the communication line 20. This security system 50 is used in a system in which communication between a first communication unit and a second communication unit is connected via the communication line 20. Note that the communication lines 20, 68, 78, 82, and 310 are components of the transmission line. Although they may be referred to as communication lines without any specific explanation, these are components of the transmission line.

[0038] The signal superimposing circuit 100 is, for example, a directional coupler, which generates a signal of a specific frequency f with a specific intensity and superimposes the generated signal on the communication line 20. Hereinafter, the signal to be superimposed may be referred to as a "superimposed signal." The signal superimposing circuit 100 includes, for example, an oscillation circuit 110 that generates a sine wave, an amplifier 112 that amplifies the signal generated by the oscillation circuit 110, and a resistor 114.

[0039] The filter unit 200 includes an open stub filter 210 (hereinafter simply referred to as "open stub 210"). The filter unit 200 is provided on the transmission line from the position where the superimposed signal is added to the communication line 20 to the position where the communication signal transmitted by the first communication unit is received by the second communication unit. The open stub 210 is a narrow-band filter configured to be able to remove the superimposed signal. Specifically, the open stub 210 has a resonant frequency f equal to the frequency f of the superimposed signal and a depth (transmission loss) that allows it to remove the signal with the intensity corresponding to the superimposed signal.

[0040] The number of superimposed signals superimposed by the signal superimposing circuit 100 is not limited to one (one type), but may be multiple (multiple types). In this case, the filter section 200 includes multiple filters corresponding to the respective superimposed signals.

[0041] FIG. 2 is a diagram showing an example of the spectrum of a signal flowing through a communication line, with the horizontal axis representing the signal frequency and the vertical axis representing the signal strength. In FIG. 2, the solid line represents an example of the spectrum of a communication signal, and the dashed line represents an example of the spectrum of a superimposed signal. Referring to FIG. 2, for example, assume that three signals with different frequency characteristics are superimposed on a communication line by a signal superimposing circuit. Superimposed signal S1 with frequency f1 and superimposed signal S2 with frequency f2 are both signals within a band used for communication between devices (hereinafter also referred to as the "communication band"). In this case, superimposed signal S1 and superimposed signal S2 are superimposed on the communication signal. On the other hand, superimposed signal S3 with frequency f3 is a signal outside the communication band.

[0042] In this disclosure, the term "communication band" refers to a frequency band used for communication between devices, and means a band that satisfies the frequency characteristics of a standard such as IEEE 802.3 (registered trademark).

[0043] 3, in the case of a normal connection (see the left column of FIG. 3) including filter unit 200 (see FIG. 1), superimposed signals S1, S2, and S3 are cut (filtered) at a desired strength by the filter formed by open stub 210. Therefore, communication between the first communication unit and the second communication unit is performed normally.

[0044] On the other hand, if an unauthorized device is connected to the first communication unit (see the right column of Figure 3), the superimposed signals S1, S2, and S3 are not removed because they do not pass through the filter unit 200. Therefore, the unauthorized device receives the communication signal with the superimposed signals S1, S2, and S3 remaining. In this case, the superimposed signals S1 and S2 become noise components such as radio noise in the communication signal and degrade the BER (Bit Error Rate). The superimposed signal S3 outside the communication band acts to saturate the received signal (receive buffer), making communication impossible. Therefore, if an unauthorized device is connected to the first communication unit, the superimposed signals make it difficult to communicate with the first communication unit.

[0045] 4, a system 40 in which the security system 50 is used includes a first in-vehicle device 60, a second in-vehicle device 70, and a wire harness 80. The wire harness 80 connects communication between the first in-vehicle device 60 and the second in-vehicle device 70. The wire harness 80 may be configured to directly connect the first in-vehicle device 60 and the second in-vehicle device 70, or may be configured to indirectly connect them via another communication line.

[0046] The wire harness 80 includes a communication line 82, a first connector 84 connected to a first end of the communication line 82, and a second connector 86 connected to a second end of the communication line 82. The first connector 84 includes a housing 84a, and the second connector 86 includes a housing 86a.

[0047] The first in-vehicle device 60 includes a first communication unit 62, a first electrical board 64 on which the first communication unit 62 is mounted, and a connector 66 provided on the first electrical board 64. The connector 66 is connected to, for example, a first connector 84 of the wire harness 80. The first electrical board 64 is provided with a communication line 68 (transmission line) that electrically connects the first communication unit 62 and the connector 66. The first electrical board 64 is further provided with the above-mentioned signal superposition circuit 100. As described above, the signal superposition circuit 100 generates a signal of a specific frequency f with a specific intensity and superposes the generated signal on the communication line 68 (20).

[0048] The second in-vehicle device 70 includes a second communication unit 72, a second electrical board 74 on which the second communication unit 72 is mounted, and a connector 76 provided on the second electrical board 74. The connector 76 is connected to, for example, a second connector 86 of the wire harness 80. The second electrical board 74 is provided with a communication line 78 (transmission line) that electrically connects the second communication unit 72 and the connector 76.

[0049] Assume that the first in-vehicle device 60 and the second in-vehicle device 70 are both ECUs. In this case, the first communication unit 62 and the second communication unit 72 include a PHY (Physical Layer). The PHY is configured by a chip mounted on the ECU that transmits and receives signals.

[0050] The communication between the first communication unit 62 and the second communication unit 72 is connected by a communication line 20. The communication line 20 includes a communication line 68, a communication line 78, and a communication line .

[0051] The above-described filter unit 200 is provided, for example, in the second connector 86 of the wire harness 80. Referring to Fig. 5, the second connector 86 includes the above-described housing 86a (connector body) and the filter unit 200 provided in the housing 86a. An end of the communication line 82 is located inside the housing 86a, and the filter unit 200 is provided, for example, on the communication line 82 inside the housing 86a.

[0052] As described above, the filter section 200 includes the open stub 210. Referring to Fig. 6, the open stub 210 is a narrow-band filter provided on the transmission line (communication line 20) and has an electrical length a. The open stub 210 serves as a band reject filter that exhibits short-circuit characteristics at a specific frequency (resonant frequency f). In other words, the open stub 210 is a filter that blocks frequency components in a band including the resonant frequency f and passes other frequency components.

[0053] The resonant frequency f is controlled by the electrical length a of the open stub 210, and the bandwidth and depth thereof are controlled by the width of the open stub 210. The shape of the open stub 210 is set so that the resonant frequency f is located in a predetermined band. In this embodiment, the shape of the open stub 210 is set so that it can remove superimposed signals.

[0054] 4 , the filter unit 200 may be provided in the first connector 84 of the wire harness 80, or in the communication line 82 of the wire harness 80. Furthermore, the filter unit 200 may be provided in the communication line 78 of the second electrical board 74, or in the connector 76 provided on the second electrical board 74. That is, the filter unit 200 may be provided on the transmission line from the position where the signal is superimposed by the signal superimposing circuit 100 to the position where the communication signal transmitted by the first communication unit 62 is received by the second communication unit 72. When the filter unit 200 includes multiple filters, the filters may be provided in the same member or in different members.

[0055] As described above, in the security system 50 according to this embodiment, the signal superposition circuit 100 superimposes a signal having a predetermined frequency characteristic onto the communication line. The superimposed signal superimposed onto the communication line is removed by the filter unit 200. Therefore, even if a superimposed signal is transmitted along with the communication signal transmitted from the first communication unit 62, the second communication unit 72 can receive the communication signal from which the superimposed signal has been removed. Therefore, communication between the first communication unit 62 and the second communication unit 72 is performed normally.

[0056] On the other hand, for example, if an unauthorized device is connected to the first communication unit 62, the superimposed signal is not removed because it does not pass through the filter unit 200. Therefore, if an unauthorized device is connected to the first communication unit 62, the superimposed signal can make it difficult for the unauthorized device to communicate with the first communication unit 62. In this way, the security system 50 can improve communication security with a simpler configuration.

[0057] That is, communication is not impeded when authentic devices are combined, but communication is impeded when an unauthorized device is connected.

[0058] The signal superimposing circuit 100 is provided on the first electrical board 64 on which the first communication unit 62 is mounted. This allows for an easy and simpler configuration.

[0059] The filter section 200 can be configured to include an open stub 210 that can remove superimposed signals, thereby enabling a simpler configuration to be easily achieved.

[0060] When communication between the first communication unit 62 and the second communication unit 72 is connected via the wire harness 80, the filter unit 200 is provided in the second connector 86 of the wire harness 80. This also makes it possible to easily achieve a simpler configuration. The filter unit 200 may be configured to be provided in the communication line 82 of the wire harness 80 or the first connector 84. In this case, the same effects as those described above can be obtained.

[0061] Furthermore, the filter unit 200 may be configured to be provided on the second electrical board 74 on which the second communication unit 72 is mounted, or on the connector 76 provided on the second electrical board 74. This also makes it possible to easily achieve a simpler configuration.

[0062] (Second embodiment) Referring to FIG. 7 , a wire harness 300 according to this embodiment is a harness using a flat cable, and includes a communication line 310, a sheet-like holding member 320 that holds the communication line 310, a first connector 330, and a second connector 340.

[0063] The sheet-like holding member 320 is made of, for example, an insulating resin material (resin sheet). The communication line 310 is wired so as to extend along the longitudinal direction of the holding member 320.

[0064] The first connector 330 is connected to a first end of the communication line 310 , and the second connector 340 is connected to a second end of the communication line 310 .

[0065] The wire harness 300 further includes a filter unit 350 similar to the above-described filter unit 200 (see FIG. 1 ) formed on the communication line 310. The filter unit 350 includes an open stub 352. The number of the filter unit 350 (open stub 352) is not limited to one, and may be multiple.

[0066] As described above, the filter section 350 may be provided in the first connector 330 or in the second connector 340 .

[0067] As a wire harness using a flat cable, an assembly harness such as e-STEALTH (registered trademark) is known. The wire harness 300 according to the present embodiment can also be configured using such an assembly harness.

[0068] According to this embodiment, it is possible to obtain a flat wire harness 300 that can improve communication security with a simpler configuration. The wire harness 300 according to this embodiment can be used in place of or together with the wire harness 80 (see FIG. 4 ) according to the first embodiment.

[0069] The other configurations and effects are the same as those of the first embodiment.

[0070] 8 , a security system 400 according to this embodiment includes a signal superposition circuit 410 that superimposes a signal component having a known frequency characteristic onto a communication line 20 (transmission line), and a signal detection circuit 420 that extracts the signal component (superimposed signal) superimposed on the communication line 20 from the communication line 20 and converts it into a 1-bit power signal (detection signal). The signal detection circuit 420 detects the superimposed signal. This security system 400 is used in a system in which communication between a first communication unit and a second communication unit is connected via the communication line 20.

[0071] The signal superimposing circuit 410 has the same configuration as the signal superimposing circuit 410 (see FIG. 1 ) shown in the first embodiment. The signal superimposing circuit 410 is, for example, a directional coupler, which generates a signal of a specific frequency f with a specific intensity and superimposes the generated signal on the communication line 20. The signal superimposing circuit 410 includes, for example, an oscillation circuit 412 that generates a sine wave, an amplifier 414 that amplifies the signal generated by the oscillation circuit 412, and a resistor 416.

[0072] The signal detection circuit 420 is, for example, a directional coupler, and includes a resistor 422, an amplifier 424 that amplifies the signal, and a diode 426. The signal detection circuit 420 is configured to be able to detect the signal superimposed by the signal superimposing circuit 410. Therefore, the signal detection circuit 420 has the opposite configuration to the signal superimposing circuit 410.

[0073] When the signal detection circuit 420 detects the superimposed signal, the second communication unit transmits a reply signal to the first communication unit.

[0074] 9, a system 40A in which the security system 400 is used includes a first in-vehicle device 60A, a second in-vehicle device 70A, and a wire harness 80A. The wire harness 80A connects communication between the first in-vehicle device 60A and the second in-vehicle device 70A. The wire harness 80A may be configured to directly connect the first in-vehicle device 60A and the second in-vehicle device 70A, or may be configured to indirectly connect them via another communication line.

[0075] The wire harness 80A includes a communication line 82 , a first connector 84 connected to a first end of the communication line 82 , and a second connector 86 connected to a second end of the communication line 82 .

[0076] The first in-vehicle device 60A includes a first communication unit 62A, a first electrical board 64 on which the first communication unit 62A is mounted, and a connector 66 provided on the first electrical board 64. The connector 66 is connected to, for example, a first connector 84 of the wire harness 80A. The first electrical board 64 is provided with a communication line 68 (transmission line) that electrically connects the first communication unit 62A and the connector 66. The first electrical board 64 is further provided with the above-mentioned signal superposition circuit 410. As described above, the signal superposition circuit 410 generates a signal of a specific frequency f with a specific intensity and superposes the generated signal on the communication line 68 (20).

[0077] The second in-vehicle device 70A includes a second communication unit 72A, a second electrical board 74 on which the second communication unit 72A is mounted, and a connector 76 provided on the second electrical board 74. The connector 76 is connected to, for example, a second connector 86 of the wire harness 80A. The second electrical board 74 is provided with a communication line 78 (transmission line) that electrically connects the second communication unit 72A and the connector 76. The second electrical board 74 is further provided with the above-mentioned signal detection circuit 420. As described above, the signal detection circuit 420 detects the superimposed signal superimposed by the signal superimposition circuit 410 and outputs a 1-bit detection signal.

[0078] The communication between the first communication unit 62A and the second communication unit 72A is connected by a communication line 20. The communication line 20 includes a communication line 68, a communication line 78, and a communication line .

[0079] [First In-Vehicle Device 60A] Referring to FIG. 10 , the first in-vehicle device 60A includes a first communication unit 62A, a signal superimposing circuit 410, and a control unit 430 that controls these. The control unit 430 includes a CPU (Central Processing Unit) 432 and a storage unit 434. The storage unit 434 stores software (computer programs) executed by the CPU 432 and various information (data). The storage unit 434 stores computer programs that cause the first in-vehicle device 60A to function as each functional unit of the first in-vehicle device 60A according to the present disclosure. The functions of each functional unit of the first in-vehicle device 60A are realized by software processing executed by the control unit 430 using hardware. Some or all of these functions may be realized by an integrated circuit including a microcomputer.

[0080] Referring to FIG. 11 , the control unit 430 includes a signal superimposing unit 440, a reply signal detecting unit 442, and a communication restricting unit 444 as functional units. The signal superimposing unit 440 controls the signal superimposing circuit 410 (see FIG. 10 ). For example, the signal superimposing unit 440 generates and superimposes (transmits) a superimposed signal at a timing that does not affect communication, or controls the signal superimposing circuit 410 to generate and superimpose a superimposed signal in a frequency band that does not affect communication. The reply signal detecting unit 442 detects a reply signal transmitted from the second in-vehicle device 70A. The communication restricting unit 444 restricts communication if the reply signal detecting unit 442 does not detect a reply signal within a predetermined time after transmitting the superimposed signal. In this case, the communication restricting unit 444 may block communication, or may block communication that poses a security risk while allowing other communication to continue.

[0081] [Second In-Vehicle Device 70A] Referring to FIG. 12 , the second in-vehicle device 70A includes a second communication unit 72A, a signal detection circuit 420, and a control unit 450 that controls these. The control unit 450 includes a CPU 452 and a storage unit 454. The storage unit 454 stores software (computer programs) executed by the CPU 452 and various information (data). The storage unit 454 stores computer programs for causing the second in-vehicle device 70A to function as each functional unit of the second in-vehicle device 70A according to the present disclosure. The functions of each functional unit of the second in-vehicle device 70A are realized by software processing executed by the control unit 450 using hardware. Some or all of these functions may be realized by an integrated circuit including a microcomputer.

[0082] 13 , control unit 450 includes, as functional units, a signal detection unit 460 and a reply signal transmission unit 462. Signal detection unit 460 detects a detection signal from signal detection circuit 420 (see FIG. 12 ). When signal detection unit 460 detects a detection signal, reply signal transmission unit 462 controls second communication unit 72A to transmit a reply signal in response to the detection of the superimposed signal to first in-vehicle device 60A (first communication unit 62A) (see FIG. 9 ). The processing by each functional unit of signal detection unit 460 and reply signal transmission unit 462 may be performed by, for example, interrupt processing of CPU 452 (see FIG. 12 ).

[0083] 8 and 9, consider a case where a second in-vehicle device 70A is connected to a first in-vehicle device 60A. The signal superposition circuit 410 of the first in-vehicle device 60A superposes a signal component having a known frequency characteristic onto the communication line 68 (20) at a predetermined timing. The signal detection circuit 420 of the second in-vehicle device 70A detects the superposed signal superposed by the signal superposition circuit 410. Upon detecting the superposed signal, the second in-vehicle device 70A transmits a reply signal to the first in-vehicle device 60A in response to the detection of the superposed signal. Upon receiving the reply signal from the second in-vehicle device 70A, the first in-vehicle device 60A recognizes that the communication partner is an authorized in-vehicle device and continues communication.

[0084] On the other hand, if an unauthorized device is connected to the first in-vehicle device 60A and the first in-vehicle device 60A does not receive a reply signal within a predetermined period after transmitting the superimposed signal, the first in-vehicle device 60A recognizes that the communication partner is an unauthorized device and restricts communication.

[0085] As described above, in the security system 400 according to this embodiment, the signal superposition circuit 410 superposes a signal having a predetermined frequency characteristic onto the communication line 68 (20). The superposed signal, which is the signal superposed onto the communication line 68 (20), is detected by the signal detection circuit 420 of the second in-vehicle device 70A. Therefore, the superposed signal can be used as an authentication signal in communication between the first communication unit 62A and the second communication unit 72A. Therefore, in the security system 400 as well, communication security can be improved with a simpler configuration.

[0086] Furthermore, the signal superimposing circuit 410 adds the superimposed signal to the communication line 68 (20) at a predetermined timing, and when the signal detection circuit 420 detects the superimposed signal, the second communication unit 72A transmits a reply signal to the first communication unit 62A in response to the detection of the superimposed signal. For example, if an unauthorized device is connected to the first in-vehicle device 60A (first communication unit 62A), the first communication unit 62A does not receive the reply signal. This allows the first in-vehicle device 60A to recognize that an unauthorized device has been connected.

[0087] The signal superposition circuit 410 may be configured to superpose an out-of-band signal used for communication onto the communication line 68 (20), thereby improving communication security while reducing the impact on communication between the first communication unit 62A and the second communication unit 72A.

[0088] The other configurations and effects are the same as those of the first embodiment.

[0089] (Modifications) In the above-described embodiment, the number of communication lines may be plural. The circuit configurations of the signal superimposing circuit and the signal detecting circuit are not limited to those shown in the above-described embodiment, and other circuit configurations may be used.

[0090] In the above-described embodiment, the signal superimposing circuit may be included in the communication unit, and the signal detecting circuit may also be included in the communication unit.

[0091] In the first embodiment, an example in which the signal superimposing circuit is provided in the first in-vehicle device has been described. However, the present disclosure is not limited to such an embodiment. The signal superimposing circuit may be provided in the second in-vehicle device. Furthermore, the signal superimposing circuit may be provided in both the first and second in-vehicle devices. In this case, the filter unit may be provided in the wire harness.

[0092] In the third embodiment described above, an example has been shown in which the first in-vehicle device is provided with a signal superposition circuit and the second in-vehicle device is provided with a signal detection circuit. However, the present disclosure is not limited to such an embodiment. For example, the second in-vehicle device may be provided with a signal superposition circuit and the first in-vehicle device may be provided with a signal detection circuit. Furthermore, both the signal superposition circuit and the signal detection circuit may be provided in the first in-vehicle device. Similarly, both the signal superposition circuit and the signal detection circuit may be provided in the second in-vehicle device.

[0093] Embodiments obtained by appropriately combining the techniques disclosed above are also included within the technical scope of the present disclosure.

[0094] The embodiments disclosed herein are merely examples, and the present disclosure is not limited to the above-described embodiments. The scope of the present disclosure is defined by the claims in the scope of the claims, taking into consideration the description of the detailed description of the invention, and includes all modifications within the meaning and scope equivalent to the wording described therein.

[0095] 20, 68, 78, 82, 310 Communication line 40, 40A System 50, 400 Security system 60, 60A First in-vehicle device 62, 62A First communication unit 64 First electrical board 66, 76 Connector 70, 70A Second in-vehicle device 72, 72A Second communication unit 74 Second electrical board 80, 80A, 300 Wire harness 84, 330 First connector 84a, 86a Housing 86, 340 Second connector 100, 410 Signal superposition circuit 110, 412 Oscillator circuit 112, 414, 424 Amplifier 114, 416, 422 Resistor 200, 350 Filter unit 210, 352 Open stub 320 Holding member 420 Signal detection circuit 426 Diode 430, 450 Control unit 432, 452 CPU 434, 454 Storage unit 440 Signal superimposing unit 442 Reply signal detecting unit 444 Communication restricting unit 460 Signal detecting unit 462 Reply signal transmitting unit S1, S2, S3 Superimposed signal

Claims

1. A security system used in a system that connects a first communication unit and a second communication unit via a communication line, A signal superposition circuit that superimposes a signal having a predetermined frequency characteristic onto the aforementioned communication line, The transmission line is provided on the transmission line from the position where the signal is superimposed by the signal superimposition circuit until the second communication unit receives the communication signal transmitted by the first communication unit, and includes a filter unit that filters the superimposed signal, which is the superimposed signal. The signal superposition circuit superimposes the out-of-band signal used for the communication onto the communication line. The signal strength of the out-of-band signal is greater than the signal strength at which the second communication unit saturates. Security system.

2. The security system according to claim 1, wherein the signal superposition circuit is provided on the first electrical circuit board on which the first communication unit is mounted.

3. The security system according to claim 1, wherein the filter unit includes an open stub filter capable of removing the superimposed signal.

4. The communication between the first communication unit and the second communication unit is connected by a wire harness. The aforementioned wire harness is The aforementioned communication line, Includes a connector connected to the end of the communication line, The security system according to any one of claims 1 to 3, wherein the filter unit is provided on the communication line or the connector.

5. The security system according to claim 4, wherein the wire harness further includes a sheet-like retaining member for holding the communication line.

6. The security system according to any one of claims 1 to 3, wherein the filter unit is provided on the second electrical circuit board on which the second communication unit is mounted, or on a connector provided on the second electrical circuit board.

7. A security system used in a system that connects a first communication unit and a second communication unit via a communication line, A signal superposition circuit is provided on the first electrical circuit board on which the first communication unit is mounted, and superimposes a signal having a predetermined frequency characteristic onto the communication line, The second communication unit is mounted on the second electrical circuit board and includes a signal detection circuit that detects the superimposed signal, which is the superimposed signal. The signal superposition circuit superimposes the out-of-band signal used for the communication onto the communication line. The signal strength of the out-of-band signal is greater than the signal strength at which the second communication unit saturates. Security system.

8. The signal superposition circuit adds the superposition signal to the communication line at a predetermined timing. The security system according to claim 7, wherein the second communication unit transmits a reply signal to the first communication unit in response to the detection of the superimposed signal when the signal detection circuit detects the superimposed signal.

9. A wire harness that connects the communication between the first communication unit and the second communication unit, Communication lines and A connector connected to the end of the communication line, The communication line or the connector includes a filter unit that filters the superimposed signal superimposed on the communication line, The superimposed signal includes an out-of-band signal used for the communication, The signal strength of the out-of-band signal is greater than the signal strength at which the second communication unit saturates. Wire harness.

10. The wire harness according to claim 9, wherein the filter section includes an open stub filter capable of removing the superimposed signal.

11. The wire harness according to claim 9 or 10, further comprising a sheet-like retaining member for holding the communication line.

12. A connector used in a system that connects a first communication unit and a second communication unit via a communication line, Housing and The housing includes a filter unit that filters the superimposed signal superimposed on the communication line, The superimposed signal includes an out-of-band signal used for the communication, The signal strength of the out-of-band signal is greater than the signal strength at which the second communication unit saturates. connector.

13. An in-vehicle device that communicates with other in-vehicle devices via a communication line, Communications Department and, The system includes a signal superposition circuit that superimposes a signal having a predetermined frequency characteristic onto the aforementioned communication line, The signal superposition circuit superimposes the out-of-band signal used for the communication onto the communication line. The signal strength of the out-of-band signal is, The signal strength is greater than the signal strength at which the communication unit of the other in-vehicle device saturates. In-vehicle device.

14. The signal superposition circuit superimposes the signal as a superimposed signal onto the communication line at a predetermined timing. The in-vehicle device according to claim 13, further comprising a communication limiting unit that limits communication if, after the superimposed signal is added, a reply signal in response to the detection of the superimposed signal is not transmitted from the other in-vehicle device.

15. An in-vehicle device that communicates with other in-vehicle devices via a communication line, Communications Department and, The system includes a signal detection circuit that detects a superimposed signal superimposed on the communication line by the other in-vehicle device, When the signal detection circuit detects the superimposed signal, the communication unit transmits a reply signal to the other in-vehicle device in response to the detection of the superimposed signal. The superimposed signal includes an out-of-band signal used for the communication, The signal strength of the out-of-band signal is greater than the signal strength at which the communication unit saturates. In-vehicle device.

16. A security system used in a system that connects a first communication unit and a second communication unit via a communication line, A signal superposition circuit that superimposes a signal having a predetermined frequency characteristic onto the aforementioned communication line, The transmission line is provided on the transmission line from the position where the signal is superimposed by the signal superimposition circuit until the second communication unit receives the communication signal transmitted by the first communication unit, and includes a filter unit that filters the superimposed signal, which is the superimposed signal. The signal strength of the superimposed signal is such that the BER (Bit Error Rate) of the second communication unit when the superimposed signal is superimposed is greater than the BER when the superimposed signal is not superimposed. Security system.

17. The security system according to claim 16, wherein the signal superposition circuit is provided on the first electrical circuit board on which the first communication unit is mounted.

18. The security system according to claim 16, wherein the filter unit includes an open stub filter capable of removing the superimposed signal.

19. The communication between the first communication unit and the second communication unit is connected by a wire harness. The aforementioned wire harness is The aforementioned communication line, Includes a connector connected to the end of the communication line, The security system according to any one of claims 16 to 18, wherein the filter unit is provided on the communication line or the connector.

20. The security system according to claim 19, wherein the wire harness further includes a sheet-like retaining member for holding the communication lines.

21. The security system according to any one of claims 16 to 18, wherein the filter unit is provided on the second electrical circuit board on which the second communication unit is mounted, or on a connector provided on the second electrical circuit board.

22. A security system used in a system that connects a first communication unit and a second communication unit via a communication line, A signal superposition circuit is provided on the first electrical circuit board on which the first communication unit is mounted, and superimposes a signal having a predetermined frequency characteristic onto the communication line, The second communication unit is mounted on the second electrical circuit board and includes a signal detection circuit that detects the superimposed signal, which is the superimposed signal. The signal strength of the superimposed signal is such that the BER of the second communication unit when the superimposed signal is superimposed is greater than the BER when the superimposed signal is not superimposed. Security system.

23. The signal superposition circuit adds the superposition signal to the communication line at a predetermined timing. The security system according to claim 22, wherein the second communication unit transmits a reply signal to the first communication unit in response to the detection of the superimposed signal when the signal detection circuit detects the superimposed signal.

24. The security system according to any one of claims 16 to 18, 22, or 23, wherein the signal superposition circuit superimposes an out-of-band signal used for the communication onto the communication line.

25. A wire harness that connects the communication between the first communication unit and the second communication unit, Communication lines and A connector connected to the end of the communication line, The communication line or the connector includes a filter unit that filters the superimposed signal superimposed on the communication line, The signal strength of the superimposed signal is such that the BER of the second communication unit when the superimposed signal is superimposed is greater than the BER when the superimposed signal is not superimposed. Wire harness.

26. The wire harness according to claim 25, wherein the filter section includes an open stub filter capable of removing the superimposed signal.

27. The wire harness according to claim 25 or claim 26, further comprising a sheet-like retaining member for holding the communication line.

28. A connector used in a system that connects a first communication unit and a second communication unit via a communication line, Housing and The housing includes a filter unit that filters the superimposed signal superimposed on the communication line, The signal strength of the superimposed signal is such that the BER of the second communication unit when the superimposed signal is superimposed is greater than the BER when the superimposed signal is not superimposed. connector.

29. An in-vehicle device that communicates with other in-vehicle devices via a communication line, Communications Department and, The system includes a signal superposition circuit that superimposes a signal having a predetermined frequency characteristic onto the aforementioned communication line, The signal strength of the superimposed signal, which is a signal superimposed on the aforementioned communication line, is such that the BER of the communication section of the other in-vehicle device deteriorates when the superimposed signal is superimposed compared to when the superimposed signal is not superimposed. In-vehicle device.

30. The signal superposition circuit superimposes the signal as a superimposed signal onto the communication line at a predetermined timing. The in-vehicle device according to claim 29, further comprising a communication limiting unit that limits the communication if, after the superimposed signal is added, a reply signal in response to the detection of the superimposed signal is not transmitted from the other in-vehicle device.

31. An in-vehicle device that communicates with other in-vehicle devices via a communication line, Communications Department and, The system includes a signal detection circuit that detects a superimposed signal superimposed on the communication line by the other in-vehicle device, When the signal detection circuit detects the superimposed signal, the communication unit transmits a reply signal to the other in-vehicle device in response to the detection of the superimposed signal. The signal strength of the superimposed signal is such that the BER of the communication unit when the superimposed signal is superimposed is greater than the BER when the superimposed signal is not superimposed. In-vehicle device.

32. The aforementioned signal superposition circuit is a directional coupler. A security system according to any one of claims 1 to 3, 7, or 8.