Wire harness, harness system, unauthorized connection prevention system, and vehicle-mounted device

Abstract

This wire harness connects a first communication unit and a second communication unit so that the units can communicate with each other. The wire harness includes a first communication line and a second communication line, wherein at least one among the first communication line and the second communication line includes a correction unit that corrects the line length difference between a communication line electrically connected to the first communication line and a communication line electrically connected to the second communication line.

Description

Wire harness, harness system, unauthorized connection prevention system, and on-board device

[0001] This disclosure relates to a wire harness, a harness system, an unauthorized connection prevention system, and an on-board device. This disclosure claims priority to Japanese Patent Application No. 2023-075916, filed May 2, 2023, and incorporates by reference all of the contents of said Japanese application.

[0002] Vehicles are equipped with various on-board devices. These on-board 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." Wire harnesses are usually used for communication between 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 technology to prevent unauthorized access to in-vehicle connectors.

[0004] The technology described in Patent Document 1 relates to a security structure for a connector. This security structure includes a protective cover that is attached to cover the mated connector. The protective cover can be released only with a dedicated tool. This protective cover prevents easy removal of a wire harness connected to the connector of the on-board device. Therefore, the security structure described in Patent Document 1 can prevent unauthorized access to the on-board device by replacing the connector or wire harness, or by probing the communication line, etc.

[0005] International Publication No. 2017 / 047567

[0006] A wire harness according to one aspect of the present disclosure is a wire harness that connects a first communication unit and a second communication unit so as to enable communication between them, and includes a first communication line and a second communication line, and at least one of the first communication line and the second communication line includes a correction unit that corrects the difference in line length between the communication line electrically connected to the first communication line and the communication line electrically connected to the second communication line.

[0007] The present disclosure can be realized not only as a wire harness, harness system, unauthorized connection prevention system, or in-vehicle device including such a characteristic configuration, but also as a recording medium recording a program for causing a computer to execute the characteristic steps executed by the in-vehicle device or unauthorized connection prevention system. Furthermore, the present disclosure can be realized as other systems or devices including the wire harness, unauthorized connection prevention system, or in-vehicle device.

[0008] FIG. 1 is a diagram for explaining an example of the configuration of a wire harness according to a first embodiment. FIG. 2 is a diagram for explaining an example of the configuration of communication lines of the wire harness shown in FIG. 1. FIG. 3 is a diagram for explaining an example of the configuration of communication lines of the wire harness shown in FIG. 1. FIG. 4 is a block diagram showing an example of the configuration of an in-vehicle device constituting the unauthorized connection prevention system according to the first embodiment. FIG. 5 is a diagram for explaining an example of the configuration of the unauthorized connection prevention system according to the first embodiment. FIG. 6 is a block diagram showing an example of the configuration of the in-vehicle device shown in FIG. 5. FIG. 7 is a diagram for explaining an example of the configuration of a wire harness according to a third embodiment. FIG. 8 is a diagram for explaining an example of the configuration of communication lines of the wire harness shown in FIG. 7. FIG. 9 is a diagram for explaining an example of the configuration of communication lines of the wire harness shown in FIG. 7. FIG. 10 is a diagram for explaining an example of the configuration of a wire harness according to a modified example. FIG. 11 is a side view seen from the S direction of FIG. 10. FIG. 12 is a diagram for explaining an example of the configuration of a wire harness according to another modified example. FIG. 13 is a diagram for explaining an example of the configuration of a wire harness according to a fourth embodiment. Fig. 14 is a plan view showing an example of a wire harness according to a fourth embodiment. Fig. 15 is a cross-sectional view taken along line CC in Fig. 14. Fig. 16 is a diagram for explaining a configuration example of a wire harness according to a fifth embodiment. Fig. 17 is a diagram for explaining a configuration example of communication lines of the wire harness shown in Fig. 16. Fig. 18 is a diagram for explaining a configuration example of a wire harness according to a sixth embodiment. Fig. 19 is a diagram for explaining a configuration example of communication lines of the wire harness shown in Fig. 18. Fig. 20 is a diagram for explaining a configuration example of communication lines of the wire harness shown in Fig. 18. Fig. 21 is a block diagram showing a configuration example of an in-vehicle device according to a modified example.

[0009] [Problem to be Solved by the Present Disclosure] The security structure described in Patent Document 1 includes a protective cover, which increases the occupied area. This may increase dimensional constraints on the design of other components such as the ECU. This may reduce the degree of freedom in design.

[0010] The present disclosure has been made to solve such problems, and one object of the present disclosure is to provide a wire harness, a harness system, an unauthorized connection prevention system, and an on-board device that can improve communication security while suppressing a reduction in design freedom.

[0011] Effect of the Present Disclosure According to the present disclosure, it is possible to provide a wire harness, a harness system, an unauthorized connection prevention system, and an in-vehicle device that can improve communication security while suppressing a decrease in design freedom.

[0012] [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.

[0013] (1) A wire harness according to a first aspect of the present disclosure is a wire harness that connects a first communication unit and a second communication unit so as to enable communication between them, and includes a first communication line and a second communication line, and at least one of the first communication line and the second communication line includes a correction unit that corrects a difference in line length between a communication line electrically connected to the first communication line and a communication line electrically connected to the second communication line.

[0014] When the wire harness of the present disclosure is used for communication between a first communication unit and a second communication unit, the difference in line length of the communication lines connecting the first communication unit and the second communication unit is corrected by the correction unit. As a result, communication between the first communication unit and the second communication unit is maintained normal. If this wire harness is removed and replaced with another wire harness that does not have the correction unit, the difference in line length is not corrected. As a result, a difference in line length occurs between the two communication lines. If communication is attempted in this state, communication performance will deteriorate. This makes it difficult to read the communication signals. In other words, normal communication will be difficult. By interfering with normal communication, unauthorized access can be prevented, thereby improving communication security.

[0015] Even if the wire harness is provided with a correction unit that corrects the wire length difference, it does not increase the occupied area, which would strengthen dimensional constraints in the design of other components such as the ECU. Therefore, the wire harness of the present disclosure can also suppress a decrease in design freedom.

[0016] (2) In the above (1), the first communication unit and the second communication unit may communicate with each other via a first transmission line and a second transmission line, the first communication line constituting a part of the first transmission line, and the second communication line constituting a part of the second transmission line. This makes it possible to easily configure a wire harness that can improve communication security while suppressing a decrease in design freedom.

[0017] (3) In the above (1) or (2), the wire harness may further include a first connector provided at first ends of the first communication line and the second communication line, and a second connector provided at second ends of the first communication line and the second communication line opposite the first ends, wherein the first communication line and the second communication line have different lengths between the first connector and the second connector. This makes it possible to easily form a correction section that corrects the difference in line length and easily prevent an increase in the occupied area.

[0018] (4) In the above (3), the correction unit may be configured to be located inside at least one of the first connector and the second connector. This allows the section in which the cable length difference is corrected to be shortened, thereby improving communication performance.

[0019] (5) In the above (3), the correction unit may be configured to be located between the first connector and the second connector, thereby increasing the degree of freedom in designing the correction unit.

[0020] (6) In the above (2), the correction unit may be configured to correct a difference in line length between the first transmission line and the second transmission line so that the line lengths of the first transmission line and the second transmission line are equal to each other, thereby improving communication performance between the first communication unit and the second communication unit.

[0021] (7) In any of the above (1) to (6), the first communication line and the second communication line may be configured as differential communication lines, in which the first communication line transmits a first signal and the second communication line transmits a second signal having a phase opposite to that of the first signal. This can degrade communication performance when the wire harness is replaced with another wire harness that does not have a correction unit, making it difficult to perform normal communication.

[0022] (8) In any of the above (1) to (6), the first communication line may transmit a data signal, and the second communication line may transmit a clock signal that synchronizes the data signal. This also makes it possible to easily make it difficult to perform normal communication by degrading communication performance when the wire harness is replaced with another wire harness that does not have a correction unit.

[0023] (9) In any one of (1) to (8) above, the wire harness may further include a sheet-like holding member that holds the first communication line and the second communication line. This makes it easy to form the correction portion.

[0024] (10) A harness system according to a second aspect of the present disclosure is a harness system including a first wire harness including a first connector and a second wire harness including a second connector connectable to the first connector, wherein the first wire harness further includes a first communication line and a second communication line connected to the first connector, the second wire harness further includes a third communication line and a fourth communication line connected to the second connector, the first communication line is connected to the third communication line via the first connector and the second connector, and the second communication line is connected to the fourth communication line via the first connector and the second connector, at least one of the first communication line and the second communication line includes a line length difference portion that causes a line length difference between the first communication line and the second communication line, and one of the third communication line and the fourth communication line that is connected to a communication line different from the communication line including the line length difference portion includes a correction portion that corrects the line length difference.

[0025] When either the first wire harness or the second wire harness is removed and replaced with another wire harness that does not have either a wire length difference portion or a correction portion, a wire length difference occurs between the two communication wires. Attempting communication in this state degrades communication performance, making it difficult to read the communication signal. Therefore, using such a harness system can improve communication security. Even if a wire length difference portion that causes a wire length difference and a correction portion that corrects the wire length difference are provided in the wire harness, this does not increase the occupied area, which would increase dimensional constraints on the design of other components such as the ECU. Therefore, the harness system of the present disclosure can also prevent a decrease in design freedom.

[0026] (11) In the above (10), the cable length difference unit may be provided in the first connector, and the correction unit may be provided in the second connector. This allows the section where the cable length difference occurs and the section where the cable length difference is corrected to be shorter, thereby improving communication performance.

[0027] (12) In the above (10) or (11), the first wire harness may further include a sheet-like holding member that holds the first communication line and the second communication line. This facilitates the formation of the wire length difference portion. Similarly, the second wire harness may further include a sheet-like holding member that holds the third communication line and the fourth communication line. In this case, the formation of the correction portion is facilitated. Note that the wire length difference portion may be a correction portion, and in this case, the correction portion may be a wire length difference portion.

[0028] (13) A third aspect of the present disclosure provides an unauthorized connection prevention system that includes a wire harness that connects a first communication unit and a second communication unit to enable communication between them, a detection unit that detects degradation in communication performance, and a determination unit that determines whether the communication is unauthorized based on the detection result of the detection unit, wherein the wire harness includes a first communication line and a second communication line, and one of the first communication line and the second communication line includes a correction unit that corrects the difference in line length between the communication line electrically connected to the first communication line and the communication line electrically connected to the second communication line.

[0029] The detection unit detects degradation of communication performance. The determination unit determines whether the communication is unauthorized based on the detection result of the detection unit. When the wire harness of the present disclosure is removed and replaced with another wire harness that does not have a correction unit, a difference in line length occurs between the two communication lines. If communication is attempted in this state, communication performance will deteriorate. The detection unit detects this degradation of communication performance. When the detection unit detects degradation of communication performance, the determination unit determines that the communication is unauthorized. By interfering with normal communication, unauthorized access can be prevented and unauthorized access can also be detected.

[0030] (14) In the above (13), the unauthorized connection prevention system may further include a communication restriction unit that restricts communication in response to the determination unit determining that communication is unauthorized. This makes it possible to more reliably prevent unauthorized access.

[0031] (15) An on-board device according to a fourth aspect of the present disclosure is an on-board device mounted on a vehicle, and includes a connector to which a wire harness is connected, a substrate on which electronic components are mounted, and a first communication line and a second communication line that transmit signals between the electronic components and the wire harness, and at least one of the first communication line and the second communication line includes a line length difference portion that generates a line length difference between the first communication line and the second communication line.

[0032] The vehicle-mounted device is provided with a wire length difference section that generates a wire length difference. When the connected wire harness is a wire harness that includes a correction section that corrects the wire length difference generated by the wire length difference section, communication is maintained normally. When the connected wire harness is replaced with another wire harness that does not have a correction section, a wire length difference occurs between the two communication lines. If communication is attempted in this state, communication performance deteriorates, making it difficult to read the communication signal. This makes it possible to prevent unauthorized access to the vehicle-mounted device.

[0033] (16) In the above (15), the cable length difference section may be provided inside the connector. This allows the section where the cable length difference occurs to be shortened, thereby improving communication performance.

[0034] (17) In the above (15), the line length difference portion may be provided on the substrate, which makes it easier to form the line length difference portion.

[0035] [Details of the embodiments of the present disclosure] Specific examples of a wire harness, a harness system, an unauthorized connection prevention system, or an on-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, the same components are assigned the same reference numerals. Their functions and names are also the same. Therefore, detailed descriptions thereof will not be repeated.

[0036] 1 , wire harnesses 100, 200, and 300 according to this embodiment are wire harnesses used for communication between on-vehicle devices. The on-vehicle devices include a first on-vehicle device 60 and a second on-vehicle device 70. The first on-vehicle device 60 includes a first communication unit 62, and the second on-vehicle device 70 includes a second communication unit 72. The wire harnesses 100, 200, and 300 connect the first communication unit 62 and the second communication unit 72 so as to enable communication between them.

[0037] 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.

[0038] The first in-vehicle device 60 further includes a substrate 64 on which the first communication unit 62 is mounted, a connector 66, and a wiring unit 68 that electrically connects the connector 66 and the first communication unit 62. The wiring unit 68 includes a first wiring 68a and a second wiring 68b. The second in-vehicle device 70 further includes a substrate 74 on which the second communication unit 72 is mounted, the connector 76, and a wiring unit 78 that electrically connects the connector 76 and the second communication unit 72. The wiring unit 78 includes a first wiring 78a and a second wiring 78b.

[0039] In the present embodiment, as an example, three wire harnesses 100, 200, and 300 are used to connect the first communication unit 62 and the second communication unit 72 so as to enable communication between them. Hereinafter, the wire harnesses 100, 200, and 300 may be referred to as the first wire harness 100, the second wire harness 200, and the third wire harness 300, respectively.

[0040] The wire harnesses 100, 200, and 300 constitute a harness system 400. The harness system may include a plurality of wire harnesses. Therefore, the number of wire harnesses constituting the harness system is not limited to three, and may be two, or may be four or more.

[0041] The first communication unit 62 and the second communication unit 72 communicate with each other using differential transmission. Therefore, the first communication unit 62 and the second communication unit 72 are connected by a differential communication line 410. The differential communication line 410 includes two communication lines through which currents of opposite phases flow. When one communication line (first transmission line 412) is a positive signal line, the other communication line (second transmission line 414) is a negative signal line. In differential transmission, the potential difference between the first transmission line 412 (positive signal line) and the second transmission line 414 (negative signal line) is treated as a signal level.

[0042] The first wire harness 100 includes a communication line 110 and a communication line 120, and a connector 130 and a connector 140 provided at both ends of the communication line 110 and the communication line 120. The communication line 110 constitutes a part of a first transmission line 412 (positive signal line), and the communication line 120 constitutes a part of a second transmission line 414 (negative signal line).

[0043] The second wire harness 200 includes a communication line 210 and a communication line 220, and a connector 230 and a connector 240 provided at both ends of the communication line 210 and the communication line 220. The communication line 210 constitutes a part of a first transmission line 412 (positive signal line), and the communication line 220 constitutes a part of a second transmission line 414 (negative signal line).

[0044] The third wire harness 300 includes a communication line 310 and a communication line 320, and connectors 330 and 340 provided at both ends of the communication line 310 and the communication line 320. The communication line 310 constitutes a part of a first transmission line 412 (positive signal line), and the communication line 320 constitutes a part of a second transmission line 414 (negative signal line).

[0045] The connector 130 of the first wire harness 100 is connected to the connector 66 of the first in-vehicle device 60. The connector 140 of the first wire harness 100 is connected to the connector 230 of the second wire harness 200. The connector 340 of the third wire harness 300 is connected to the connector 76 of the second in-vehicle device 70. The connector 330 of the third wire harness 300 is connected to the connector 240 of the second wire harness 200.

[0046] 2 , in one section of the differential communication line 410, one communication line is longer than the other communication line, and in another section of the differential communication line 410, the other communication line is longer than the one communication line. The differential communication line 410 is configured so that one communication line and the other communication line are equal in length over the entire length L1. That is, in each of the first wire harness 100, the second wire harness 200, and the third wire harness 300, the two communication lines have different lengths. The difference in line length between the two communication lines in each wire harness complements each other among multiple wire harnesses.

[0047] More specifically, for example, the first wire harness 100 is configured such that the communication line 120 constituting a part of the second transmission line 414 (negative signal line) is longer than the communication line 110 constituting a part of the first transmission line 412 (positive signal line). The third wire harness 300 is also configured such that the communication line 320 constituting a part of the second transmission line 414 (negative signal line) is longer than the communication line 310 constituting a part of the first transmission line 412 (positive signal line). On the other hand, the second wire harness 200 is configured such that the communication line 210 constituting a part of the first transmission line 412 (positive signal line) is longer than the communication line 220 constituting a part of the second transmission line 414 (negative signal line). As described above, the differential communication line 410 is configured so that the first transmission line 412 (positive signal line) and the second transmission line 414 (negative signal line) have the same length over the entire length L1.

[0048] The wire length difference in each wire harness is formed by bending (for example, undulating) a portion of the communication wire. Specifically, the communication wire 120 of the first wire harness 100 is provided with a wire length difference portion 122 that makes the communication wire 120 have a wire length different from that of the communication wire 110 by bending (undulating) a portion of the communication wire 120. The wire length difference portion 122 makes the communication wire 120 longer than the communication wire 110. In other words, the wire length difference is caused by the wire length difference portion 122. The wire length difference portion 122 is provided so as to be located inside the connector 140 of the first wire harness 100.

[0049] The communication line 210 of the second wire harness 200 is provided with line length difference sections 212 and 214, which are formed by bending (e.g., undulating) a portion of the communication line 210 to make the communication line 210 have a different line length from the communication line 220. The line length difference sections 212 and 214 make the line length of the communication line 210 longer than the communication line 220. In other words, the line length difference sections 212 and 214 cause a difference in line length. The line length difference section 212 is provided so as to be located inside the connector 230 of the second wire harness 200, and the line length difference section 214 is provided so as to be located inside the connector 240 of the second wire harness 200.

[0050] The communication line 310 of the third wire harness 300 is provided with a line length difference portion 322 that makes the communication line 310 have a line length different from that of the communication line 320 by bending (e.g., undulating) a portion of the communication line 310. The line length difference portion 322 makes the line length of the communication line 320 longer than that of the communication line 310. In other words, the line length difference portion 322 causes a line length difference. The line length difference portion 322 is provided so as to be located inside the connector 330 of the third wire harness 300.

[0051] In each of the wire harnesses 100, 200, and 300, the communication lines having the different line length portions may be reversed.

[0052] 3 , each connector includes a signal pin for electrically connecting the communication lines to each other. For example, connector 140 of first wire harness 100 includes signal pin 142 connected to communication line 110 and signal pin 144 connected to communication line 120. Connector 230 of second wire harness 200 includes signal pin 232 connected to communication line 210 and signal pin 234 connected to communication line 220. Connector 240 of second wire harness 200 includes signal pin 242 connected to communication line 210 and signal pin 244 connected to communication line 220. Connector 330 of third wire harness 300 includes signal pin 332 connected to communication line 310 and signal pin 334 connected to communication line 320.

[0053] When the connector 140 of the first wire harness 100 and the connector 230 of the second wire harness 200 are connected, the signal pin 142 of the connector 140 and the signal pin 232 of the connector 230 are connected, and the signal pin 144 of the connector 140 and the signal pin 234 of the connector 230 are connected. As a result, the communication line 110 of the first wire harness 100 and the communication line 210 of the second wire harness 200 are electrically connected, and the communication line 120 of the first wire harness 100 and the communication line 220 of the second wire harness 200 are electrically connected.

[0054] Similarly, when the connector 240 of the second wire harness 200 and the connector 330 of the third wire harness 300 are connected, the signal pin 242 of the connector 240 and the signal pin 332 of the connector 330 are connected, and the signal pin 244 of the connector 240 and the signal pin 334 of the connector 330 are connected. As a result, the communication line 210 of the second wire harness 200 and the communication line 310 of the third wire harness 300 are electrically connected, and the communication line 220 of the second wire harness 200 and the communication line 320 of the third wire harness 300 are electrically connected.

[0055] The wire length difference portion 122 of the first wire harness 100 is provided before the signal pin 144, and the wire length difference portion 212 of the second wire harness 200 is provided before the signal pin 232. Similarly, the wire length difference portion 214 of the second wire harness 200 is provided before the signal pin 242, and the wire length difference portion 322 of the third wire harness 300 is provided before the signal pin 334.

[0056] In the present embodiment, the wire length of the wire length difference portion 122 in the first wire harness 100 is set to be equal to the wire length of the wire length difference portion 212 in the second wire harness 200. The wire length of the wire length difference portion 322 in the third wire harness 300 is set to be equal to the wire length of the wire length difference portion 214 in the second wire harness 200. When the wire length difference portion 122 in the first wire harness 100 is set to be a wire length difference portion that causes a wire length difference between two communication lines, the wire length difference portion 212 in the second wire harness 200 functions as a correction portion that corrects the wire length difference. Similarly, when the wire length difference portion 322 in the third wire harness 300 is set to be a wire length difference portion that causes a wire length difference between two communication lines, the wire length difference portion 214 in the second wire harness 200 functions as a correction portion that corrects the wire length difference.

[0057] In addition, if the wire length difference sections 212 and 214 in the second wire harness 200 are each configured as wire length difference sections that cause a wire length difference between the two communication lines, the wire length difference section 122 in the first wire harness 100 and the wire length difference section 322 in the third wire harness 300 function as correction sections that correct the wire length difference that has occurred in the second wire harness 200.

[0058] Referring again to FIG. 2, over the entire length L1 of the differential communication line 410, the two communication lines (the first transmission line 412 (positive signal line) and the second transmission line 414 (negative signal line)) are of equal length, and therefore communication between the first communication unit 62 and the second communication unit 72 is maintained normally.

[0059] Consider, for example, a case where unauthorized access is made to the first communication unit 62 (first in-vehicle device 60). In this case, it is possible that the second wire harness 200 is removed from the first wire harness 100 and another wire harness is connected to the connector 140 of the first wire harness 100. Then, an unauthorized access is attempted to the first in-vehicle device 60 via the other connected wire harness.

[0060] The connected wire harness typically does not have a correction section (wire length difference section) for correcting the wire length difference of the first wire harness 100. Therefore, the wire length difference section 122 of the first wire harness 100 causes a wire length difference between the two communication lines that make up the differential communication line. If communication is attempted in this state, a time lag occurs between the signal flowing through one of the two communication lines and the signal flowing through the other communication line, degrading communication performance. This makes it difficult to read the communication signals. In other words, it becomes difficult to perform normal communication. By preventing normal communication, unauthorized access (unauthorized connection) can be prevented, thereby improving communication security.

[0061] 1 , the above-described first wire harness 100, second wire harness 200, or third wire harness 300 can be used in the unauthorized connection prevention system 50. The unauthorized connection prevention system 50 according to this embodiment includes a first in-vehicle device 60 including a first communication unit 62, a second in-vehicle device 70 including a second communication unit 72, and a wire harness connecting the first communication unit 62 and the second communication unit 72 so as to enable communication between them.

[0062] The unauthorized connection prevention system 50 may be configured to include a first wire harness 100, a second wire harness 200, and a third wire harness 300 as wire harnesses that connect the first communication unit 62 and the second communication unit 72 so as to enable communication between them. Note that the unauthorized connection prevention system 50 is not limited to this configuration, and may be configured to include some of the wire harnesses of the first wire harness 100, the second wire harness 200, and the third wire harness 300. The number of wire harnesses that make up the unauthorized connection prevention system 50 is not limited to three, and may be one, two, or a plurality of four or more.

[0063] 4 , first in-vehicle device 60 further includes a control unit 80 and a storage unit 90. Control unit 80 includes a computing element (processor) such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). Control unit 80 includes, as functional units, a detection unit 82 that detects degradation of communication performance, a determination unit 84 that determines whether communication is unauthorized based on the detection result of detection unit 82, and a communication restriction unit 86 that restricts communication based on the determination result of determination unit 84.

[0064] The first communication unit 62 communicates with other in-vehicle devices via differential transmission. The first communication unit 62 transmits and receives differential signals. Specifically, the first communication unit 62 transmits a first signal (positive) and a second signal (negative) having an opposite phase to the first signal to the wiring unit 68 (first wiring 68a, second wiring 68b) (see FIG. 1 ). The storage unit 90 includes a non-volatile memory such as a flash memory. The storage unit 90 stores software (computer programs) executed by the control unit 80 and various information (data). The functions of each functional unit of the first in-vehicle device 60 are realized by software processing executed by the control unit 80 using hardware. Some or all of these functions may be realized by an integrated circuit including a microcomputer.

[0065] The second in-vehicle device 70 may have the same configuration as the first in-vehicle device 60 .

[0066] The detection unit 82 may be configured to use a function such as an error counter of the ECU. The determination unit 84 determines that unauthorized communication is occurring when, for example, the communication degradation detected by the detection unit 82 is greater than a predetermined threshold (the degree of degradation is large). The communication restriction unit 86 restricts communication in response to the determination by the determination unit 84 that the communication is unauthorized. Note that the communication restriction unit 86 may block communication as necessary.

[0067] As described above, when the wire harness 100, 200, or 300 according to the present embodiment is used for communication between the first communication unit 62 and the second communication unit 72, the difference in line length of the communication lines connecting the first communication unit 62 and the second communication unit 72 is corrected by the correction unit (line length difference unit). This maintains normal communication between the first communication unit 62 and the second communication unit 72. If this wire harness is removed and replaced with another wire harness that does not have the correction unit (line length difference unit), the difference in line length is not corrected. As a result, a difference in line length occurs between the two communication lines. If communication is attempted in this state, communication performance deteriorates. This makes it difficult to read the communication signals. In other words, normal communication is difficult. By interfering with normal communication, unauthorized access can be prevented, thereby improving communication security.

[0068] Even if the wire harness is provided with a correction portion (wire length difference portion) that corrects the wire length difference, it does not increase the occupied area, which would strengthen dimensional constraints in the design of other components such as the ECU. Therefore, the wire harness 100, 200 or 300 according to the present embodiment can prevent a decrease in design freedom.

[0069] The first communication unit 62 and the second communication unit 72 communicate with each other via the first transmission line 412 and the second transmission line 414, and the communication lines of each of the wire harnesses 100, 200, and 300 form part of the first transmission line 412 and the second transmission line 414. This makes it possible to easily configure a wire harness that can improve communication security while suppressing a decrease in design freedom.

[0070] The first wire harness 100 further includes a connector 130 provided at one end (first end) of the communication line 110 and the communication line 120, and a connector 140 provided at the other end (second end) of the communication line 110 and the communication line 120, and the communication lines 110 and 120 have different lengths between the connectors 130 and 140. This makes it possible to easily form a correction section (line length difference section 122) that corrects the difference in line length and to easily prevent an increase in the occupied area. The same applies to the second wire harness 200 and the third wire harness 300.

[0071] By providing the wire length difference portion 122 of the first wire harness 100 inside the connector 140, the section where the wire length difference is corrected (or the section where the wire length difference occurs) can be shortened, thereby improving communication performance. The same effect can be obtained by configuring the second wire harness 200 and the third wire harness 300 in the same way.

[0072] By using the wire harnesses 100, 200 and 300 according to the present embodiment for differential transmission communication, when they are replaced with another wire harness that does not have a correction section, the communication performance can be degraded, making it easily difficult to carry out normal communication.

[0073] Similarly to the above, the harness system 400 can also improve communication security while suppressing a decrease in design freedom.

[0074] In addition to the wire harness 100, 200, or 300, the unauthorized connection prevention system 50 further includes a detection unit 82 that detects degradation of communication performance, a determination unit 84 that determines whether communication is unauthorized based on the detection result of the detection unit 82, and a communication restriction unit 86 that restricts communication based on the determination result of the determination unit 84. This makes it possible to detect unauthorized access and restrict communication, thereby further improving communication security. As a result, unauthorized access can be more reliably prevented.

[0075] Second Embodiment Referring to FIG. 5 , an unauthorized network connection prevention system 50A according to this embodiment differs from the first embodiment in that it communicates using a transmission method other than differential transmission. The unauthorized network connection prevention system 50A includes a first in-vehicle device 60A and a second in-vehicle device 70A instead of the first in-vehicle device 60 (see FIG. 1 ) and the second in-vehicle device 70 (see FIG. 1 ). The first in-vehicle device 60A includes a first communication unit 62A instead of the first communication unit 62 (see FIG. 1 ). The second in-vehicle device 70A includes a second communication unit 72A instead of the second communication unit 72 (see FIG. 1 ). The first in-vehicle device 60A (first communication unit 62) and the second in-vehicle device 70A (second communication unit 72A) communicate with each other using, for example, single-ended transmission.

[0076] 6, first communication unit 62A communicates with other in-vehicle devices using single-ended transmission. Specifically, first communication unit 62A transmits a data signal and a clock signal that synchronizes the data signal to wiring unit 68 (first wiring 68a, second wiring 68b) (see FIG. 5).

[0077] The second communication unit 72A of the second in-vehicle device 70A may have the same configuration as the first communication unit 62A of the first in-vehicle device 60A.

[0078] Even with this configuration, when any of the wire harnesses 100, 200, and 300 is replaced with another wire harness, the communication performance can be degraded, making it difficult to perform normal communication.

[0079] The other configurations and effects are the same as those of the first embodiment.

[0080] 7, an unauthorized connection prevention system 50B according to this embodiment includes a harness system 402 instead of the harness system 400 (see FIG. 1). The harness system 402 includes a second wire harness 500 instead of the second wire harness 200 (see FIG. 1).

[0081] The second wire harness 500 is a harness using a flat cable, and includes a communication line 510 and a communication line 520, a sheet-like holding member 530 that holds the communication lines 510 and 520, and connectors 540 and 550. The connector 540 is provided at a first end in the longitudinal direction of the holding member 530. The connector 550 is provided at a second end of the holding member 530 that is opposite to the first end in the longitudinal direction.

[0082] The sheet-like holding member 530 is made of, for example, an insulating resin material (resin sheet). The communication lines 510 and 520 have a configuration in which conductive core wires are covered with insulating resin. The communication lines 510 and 520 are wired so as to extend along the longitudinal direction of the holding member 530. The communication lines 510 and 520 are fixed (welded) to a first main surface (e.g., the upper surface) of the sheet-like holding member 530 by, for example, ultrasonic welding or laser welding.

[0083] Referring to FIG. 8 , the communication line 510 of the second wire harness 500 has wire length difference portions 512 and 514 formed by bending (e.g., undulating) portions of the communication line 510 to make the communication line 510 have a different wire length from the communication line 520. These wire length difference portions 512 and 514 make the communication line 510 longer than the communication line 520. The wire length difference portions 512 and 514 are not provided inside the connectors 540 and 550, but are provided at predetermined positions between the connectors 540 and 550. A configuration using a flat cable increases the automation of routing, making it easier to provide wire length differences (wire length difference portions 512 and 514). Therefore, the number of processing steps can be reduced compared to when the wire length difference portions are provided inside the connectors. However, the wire length difference portions 512 and 514 may also be provided inside the connectors 540 and 550, respectively.

[0084] 9 , the wire length of the wire length difference portion 512 in the second wire harness 500 is set to be equal to, for example, the wire length of the wire length difference portion 122 in the first wire harness 100. The wire length of the wire length difference portion 514 in the second wire harness 500 is set to be equal to, for example, the wire length of the wire length difference portion 322 in the third wire harness 300.

[0085] 8 , one communication line (first transmission line 412) and the other communication line (second transmission line 414) are configured to have the same length over the entire length L2 of the differential communication line. Note that, as long as the first transmission line 412 and the second transmission line 414 are configured to have the same length over the entire length L2, the wire length of the wire length difference portion 512 in the second wire harness 500 does not have to be equal to the wire length of the wire length difference portion 122 in the first wire harness 100. Similarly, the wire length of the wire length difference portion 514 in the second wire harness 500 does not have to be equal to the wire length of the wire length difference portion 322 in the third wire harness 300.

[0086] The other configurations and effects are the same as those of the first or second embodiment.

[0087] (Modification) In the above embodiment, an example has been shown in which the line length difference portions 512 and 514 are formed by bending a portion of the communication line 510 on the first main surface (top surface) of the holding member 530. However, the present disclosure is not limited to such an embodiment. The line length difference portions 512 and 514 may be configured to cause a line length difference between the communication line 510 and the communication line 520, or to correct a line length difference occurring in other wire harnesses, etc.

[0088] 10 , a wire harness 502 according to this modification is a harness using a flat cable, similar to the second wire harness 500 (see FIG. 7 ). The wire harness 502 includes a sheet-shaped holding member 532 instead of the sheet-shaped holding member 530 (see FIG. 7 ). The sheet-shaped holding member 532 has through-holes 532a, 532b, 532c, and 532d that penetrate the member in the thickness direction. In the wire harness 502 according to this modification, a wire length difference portion 518 is formed by passing a portion of the communication wire 510 through the through-holes 532a and 532b to the lower surface side of the holding member 532. Similarly, another portion of the communication wire 510 through the through-holes 532c and 532d to the lower surface side of the holding member 532 to form the wire length difference portion 518.

[0089] 11 , the line length difference portion 516 is formed by routing the communication line 510 so that a portion of the communication line 510 is provided on a second main surface (lower surface) 532f opposite to the first main surface (upper surface) 532e of the holding member 532. The same applies to the line length difference portion 518. The difference in line length caused by the line length difference portions 516 and 518 is adjusted by changing the length of the communication line 510 provided on the second main surface (lower surface) 532f side.

[0090] A harness using a flat cable may be an assembly harness in which three or more communication lines (electric wires) are wired. In this case, the harness may have a laminated structure in which multiple sheet-like holding members are stacked. When the wire harness has multiple layers due to the laminated structure, the communication lines may be wired across the layers to form a different wire length section.

[0091] 12 , for example, consider a case where two sheet-like holding members 534 and 536 are stacked. In this case, the communication line 510 may be wired across layers. This allows a line length difference portion 516 a to be formed in the portion of the communication line 510 that is wired across layers.

[0092] (Fourth embodiment) Referring to Figure 13, the unauthorized connection prevention system 50C of this embodiment differs from the third embodiment in that it includes a second wire harness 600 instead of the second wire harness 500 (see Figure 7).

[0093] Referring to Fig. 14, the second wire harness 600 is a harness using a flat cable. Referring to Fig. 15, the second wire harness 600 further includes a cover sheet 610 provided on a sheet-like holding member 530 to cover the communication lines 510 and 520. The cover sheet 610 has the same size as the holding member 530 and is provided on top of the holding member 530. The cover sheet 610 is made of, for example, an opaque resin material. The cover sheet 610 makes it difficult to see the wiring state of the communication lines 510 and 520 from the outside. Since the presence of the line length difference portions 512 and 514 can be made difficult to notice, communication security can be further improved.

[0094] The other configurations and effects are the same as those of the third embodiment.

[0095] 16 , an unauthorized connection prevention system 50D according to this embodiment differs from the third embodiment in that it includes a second wire harness 700 instead of the second wire harness 500 (see FIG. 7 ). The second wire harness 700 is a harness that uses a flat cable, similar to the third embodiment. However, the second wire harness 700 differs from the second wire harness 500 according to the third embodiment (see FIG. 7 ) in the attachment position of the connector.

[0096] The second wire harness 700 includes a communication line 710 and a communication line 720, a sheet-like holding member 530 that holds the communication lines 710 and 720, and connectors 540 and 550. The connector 540 is provided on one side of the holding member 530 at a first end in the longitudinal direction of the holding member 530. The connector 540 is provided on one side of the holding member 530 at a second end opposite the first end in the longitudinal direction of the holding member 530. The communication lines 710 and 720 are bent toward the connector 540 at the first end of the holding member 530 and wired. The communication lines 710 and 720 are also bent toward the connector 550 at the second end of the holding member 530 and wired.

[0097] The communication line 710 of the second wire harness 700 is provided with wire length difference portions 712 and 714. When the connectors 540 and 550 are provided on the side of the holding member 530, the communication line 710 is on the outer periphery and the communication line 720 is on the inner periphery. Therefore, even if the wire length difference portions 712 and 714 are not provided, a wire length difference occurs between the two communication lines. The wire length difference portions 712 and 714 are set in consideration of this inevitable wire length difference.

[0098] Referring to Figure 17, the total wire length of the wire length difference section 712 and the wire length difference section 714 in the second wire harness 700 is equivalent to the total wire length of the wire length difference section 122 in the first wire harness 100 and the wire length of the wire length difference section 322 in the third wire harness 300 minus the wire length difference that inevitably occurs (the difference between the outer circumference and the inner circumference).

[0099] In this way, the second wire harness 700 according to the present embodiment can be easily applied to such wire harnesses (wire harnesses in which wire length differences inevitably occur) because it is not necessary to separately eliminate the wire length differences that inevitably occur by providing the wire length difference sections 712 and 714.

[0100] The other configurations and effects are the same as those of the third embodiment.

[0101] (Sixth embodiment) Referring to Figure 18, the unauthorized connection prevention system 50E according to this embodiment includes a first vehicle-mounted device 760 including a first communication unit 62, a second vehicle-mounted device 770 including a second communication unit 72, and a wire harness 800 that connects the first communication unit 62 and the second communication unit 72 so as to enable communication between them.

[0102] The first communication unit 62 and the second communication unit 72 communicate with each other, for example, by differential transmission. The first communication unit 62 and the second communication unit 72 are connected to each other by a differential communication line 420. As described above, the differential communication line 420 includes two communication lines (a first transmission line 422 and a second transmission line 424) through which currents of opposite phases flow. Note that the first communication unit 62 and the second communication unit 72 may be configured to communicate with each other by a method other than differential transmission, for example, single-ended transmission.

[0103] The wire harness 800 has a configuration similar to that of the second wire harness 200 (see FIG. 2 ). That is, the wire harness 800 includes a communication line 810 and a communication line 820, and a connector 830 and a connector 840 provided at both ends of the communication line 810 and the communication line 820. The communication line 810 constitutes a part of the first transmission line 422, and the communication line 820 constitutes a part of the second transmission line 424.

[0104] The first in-vehicle device 760 includes a first communication unit 62, a substrate 64 on which the first communication unit 62 is mounted, a connector 66, and a wiring unit 768 that electrically connects the connector 66 and the first communication unit 62. The wiring unit 768 includes a first wiring 768a and a second wiring 768b. The second in-vehicle device 770 includes a second communication unit 72, a substrate 74 on which the second communication unit 72 is mounted, the connector 76, and a wiring unit 778 that electrically connects the connector 76 and the second communication unit 72. The wiring unit 778 includes a first wiring 778a and a second wiring 778b.

[0105] 19 , in one section of the differential communication line 420, one communication line is longer than the other communication line, and in another section of the differential communication line 420, the other communication line is longer than the one communication line. The differential communication line 420 is configured so that the one communication line and the other communication line are equal in length over the entire length L3. That is, the wire harness 800 has two communication lines that are different in length, and the wiring portion 768 and the wiring portion 778 each have two wires that are different in length.

[0106] Specifically, wire harness 800 has two communication lines, and communication line 810 is provided with line length difference portions 812 and 814. Line length difference portions 812 and 814 are formed by bending (e.g., undulating) a portion of communication line 810, and communication line 810 has a different line length from communication line 820. In other words, line length difference portions 812 and 814 make communication line 810 longer than communication line 820. Line length difference portion 812 is provided so as to be located inside connector 830 of wire harness 800, and line length difference portion 814 is provided so as to be located inside connector 840 of wire harness 800.

[0107] The wiring 768b of the first in-vehicle device 760 is provided with a line length difference portion 762 that makes the wiring 768b have a line length different from that of the wiring 768a by bending (e.g., undulating) a portion of the wiring 768b. This line length difference portion 762 makes the wiring 768b longer than the wiring 768a. In other words, the line length difference portion 762 causes a difference in line length between the two wires that make up the wiring portion 768. This line length difference portion 762 is provided so as to be located inside the connector 66 of the first in-vehicle device 760.

[0108] Similarly, a line length difference portion 772 is provided in the wiring 778b of the second in-vehicle device 770, where a portion of the wiring 778b is bent (for example, undulated) to make the wiring 778b have a different line length from the wiring 778a. This line length difference portion 772 makes the line length of the wiring 778b longer than the wiring 778a. In other words, the line length difference portion 772 causes a difference in line length between the two wires that make up the wiring portion 778. This line length difference portion 772 is provided so as to be located inside the connector 76 of the second in-vehicle device 770.

[0109] In the wire harness 800, the communication line in which the line length difference portion is provided may be the communication line 820. In this case, the line length difference portion of the first in-vehicle device 760 is provided in the wiring 768a, and the line length difference portion of the second in-vehicle device 770 is provided in the wiring 778a.

[0110] 20 , each connector includes a signal pin for electrically connecting the communication lines. Specifically, connector 830 of wire harness 800 includes a signal pin 832 connected to communication line 810 and a signal pin 834 connected to communication line 820. Connector 66 of first in-vehicle device 760 includes a signal pin 66a connected to wiring 768a and a signal pin 66b connected to wiring 768b. Connector 76 of second in-vehicle device 770 includes a signal pin 76a connected to wiring 778a and a signal pin 76b connected to wiring 778b.

[0111] When the connector 830 of the wire harness 800 and the connector 66 of the first in-vehicle device 760 are connected, the signal pin 832 of the connector 830 is connected to the signal pin 66a of the connector 66, and the signal pin 834 of the connector 830 is connected to the signal pin 66b of the connector 66. As a result, the communication line 810 of the wire harness 800 is electrically connected to the wiring 768a of the first in-vehicle device 760, and the communication line 820 of the wire harness 800 is electrically connected to the wiring 768b of the first in-vehicle device 760.

[0112] Similarly, when the connector 840 of the wire harness 800 and the connector 76 of the second in-vehicle device 770 are connected, the signal pin 842 of the connector 840 and the signal pin 76a of the connector 76 are connected, and the signal pin 844 of the connector 840 and the signal pin 76b of the connector 76 are connected. As a result, the communication line 810 of the wire harness 800 and the wiring 778a of the second in-vehicle device 770 are electrically connected, and the communication line 820 of the wire harness 800 and the wiring 778b of the second in-vehicle device 770 are electrically connected.

[0113] The wire length difference portion 812 of the wire harness 800 is provided before the signal pin 832, and the wire length difference portion 762 of the first in-vehicle device 760 is provided before the signal pin 66b. Similarly, the wire length difference portion 814 of the wire harness 800 is provided before the signal pin 842, and the wire length difference portion 772 of the second in-vehicle device 770 is provided before the signal pin 76b.

[0114] In the present embodiment, the wire length of the wire length difference portion 812 in the wire harness 800 is set to be equal to the wire length of the wire length difference portion 762 in the first in-vehicle device 760. The wire length of the wire length difference portion 814 in the wire harness 800 is set to be equal to the wire length of the wire length difference portion 772 in the second in-vehicle device 770. When the wire length difference portion 762 in the first in-vehicle device 760 is set to be a wire length difference portion that causes a wire length difference between two wires, the wire length difference portion 812 in the wire harness 800 functions as a correction portion that corrects the wire length difference. Similarly, when the wire length difference portion 772 in the second in-vehicle device 770 is set to be a wire length difference portion that causes a wire length difference between two wires, the wire length difference portion 814 in the wire harness 800 functions as a correction portion that corrects the wire length difference.

[0115] In addition, if the wire length difference sections 812 and 814 in the wire harness 800 are each wire length difference sections that cause a wire length difference between the two communication lines, the wire length difference section 762 of the first in-vehicle device 760 and the wire length difference section 772 of the second in-vehicle device 770 function as correction sections that correct the wire length difference that has occurred in the wire harness 800.

[0116] (Modification) In the above embodiment, the configuration has been described in which the wire length difference unit 762 of the first in-vehicle device 760 is provided inside the connector 66, and the wire length difference unit 772 of the second in-vehicle device 770 is provided inside the connector 76. However, the present disclosure is not limited to such an embodiment. At least one of the wire length difference unit 762 of the first in-vehicle device 760 and the wire length difference unit 772 of the second in-vehicle device 770 may be configured to be provided on a substrate.

[0117] 21 , in-vehicle device 780 includes a communication unit 782, a substrate 784 on which communication unit 782 is mounted, a connector 786, and a wiring unit 788 that electrically connects connector 786 and communication unit 782. Wiring unit 788 includes a first wiring 788a and a second wiring 788b. One of the wirings (e.g., wiring 788b) of in-vehicle device 780 is provided with a line length difference portion 790 in which a portion of wiring 788b is bent (e.g., undulated) to make wiring 788b have a different line length from wiring 788a. This line length difference portion 790 makes the line length of wiring 788b longer than that of wiring 788a. This line length difference portion 790 is provided so as to be located on substrate 784.

[0118] The other configurations and effects are the same as those of the first or second embodiment.

[0119] In the above embodiment, an example in which the line length difference section is provided in one of the communication lines has been described. However, the present disclosure is not limited to such an embodiment. A line length difference section may be provided in both communication lines as long as it is a configuration in which a line length difference is generated between the two communication lines or a line length difference is corrected. A plurality of line length difference sections may be provided at predetermined locations on the communication lines. The line length of one line length difference section may be equal to or different from the line length of the other line length difference section.

[0120] In the above embodiment, an example has been shown in which the two communication lines are configured to have equal lengths over the entire length of the differential communication line. However, the present disclosure is not limited to such an embodiment. The two communication lines do not need to have equal lengths as long as the signal degradation is within an acceptable range.

[0121] When providing a line length difference portion on a substrate of an in-vehicle device, if the substrate is a laminated substrate, the line length difference portion may be provided on an inner layer.

[0122] The technology using the wire harness according to the above embodiment can also be used to detect incorrect installation of a wire harness. The part number of the wire harness may be determined depending on the vehicle model, the installation section of the wire harness, etc. In such a case, if a wire length difference section is set so that communication degradation occurs when a wire harness with a different part number is installed, incorrect installation of the wire harness can be prevented.

[0123] Embodiments obtained by appropriately combining the techniques disclosed above are also included within the technical scope of the present disclosure.

[0124] 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.

[0125] 50, 50A, 50B, 50C, 50D, 50E Unauthorized connection prevention system 60, 60A, 760 First in-vehicle device 62, 62A First communication unit 64, 74, 784 Board 66, 76, 130, 140, 230, 240, 330, 340, 540, 550, 786, 830, 840 Connector 68, 78, 768, 778, 788 Wiring unit 68a, 68b, 78a, 78b, 768a, 768b, 778a, 778b, 788a, 788b Wiring 70, 70A, 770 Second in-vehicle device 72, 72A Second communication unit 80 Control unit 82 Detection unit 84 Determination unit 86 Communication restriction unit 90 Storage unit 100 First wire harness 110, 120, 210, 220, 310, 320, 510, 520, 710, 720, 810, 820 Communication line 122, 212, 214, 322, 512, 514, 516, 516a, 518, 712, 714, 762, 772, 790, 812, 814 Wire length difference section 142, 144, 232, 234, 242, 244, 332, 334, 66a, 66b, 76a, 76b, 832, 834, 842, 844 Signal pin 200, 500, 600, 700 Second wire harness 300 Third wire harness 400, 402 Harness system 410, 420 Differential communication line 412, 422 First transmission line 414, 424 Second transmission line L1, L2, L3 Total length 530, 532, 534, 536 Holding member 502, 800 Wire harness 532a, 532b, 532c, 532d Through hole 532e Upper surface 532f Lower surface 610 Cover sheet 780 On-board device 782 Communication unit

Claims

1. A wire harness that connects a first communication unit and a second communication unit so as to enable communication between them, a first communication line and a second communication line; At least one of the first communication line and the second communication line includes a correction unit that corrects a difference in line length between a communication line electrically connected to the first communication line and a communication line electrically connected to the second communication line.

2. the first communication unit and the second communication unit communicate with each other via a first transmission line and a second transmission line; the first communication line constitutes a part of the first transmission line; The wire harness according to claim 1 , wherein the second communication line constitutes a part of the second transmission line.

3. a first connector provided at a first end of the first communication line and the second communication line; a second connector provided at a second end of the first communication line and the second communication line opposite to the first end, 3. The wire harness according to claim 1, wherein the first communication line and the second communication line have different lengths between the first connector and the second connector.

4. The wire harness according to claim 3 , wherein the correction portion is located inside at least one of the first connector and the second connector.

5. The wire harness according to claim 3 , wherein the correction portion is located between the first connector and the second connector.

6. The wire harness according to claim 2 , wherein the correction unit corrects the difference in line length so that the first transmission line and the second transmission line have the same line length.

7. the first communication line and the second communication line constitute a differential communication line; the first communication line transmits a first signal; 7. The wire harness according to claim 1, wherein the second communication line transmits a second signal having a phase opposite to that of the first signal.

8. the first communication line transmits a data signal; 7. The wire harness according to claim 1, wherein the second communication line transmits a clock signal that synchronizes the data signal.

9. The wire harness according to claim 1 , further comprising a sheet-like holding member that holds the first communication line and the second communication line.

10. A harness system including a first wire harness including a first connector and a second wire harness including a second connector connectable to the first connector, the first wire harness further includes a first communication line and a second communication line connected to the first connector; the second wire harness further includes a third communication line and a fourth communication line connected to the second connector; the first communication line is connected to the third communication line via the first connector and the second connector; the second communication line is connected to the fourth communication line via the first connector and the second connector; at least one of the first communication line and the second communication line includes a line length difference portion that causes a line length difference between the first communication line and the second communication line; A harness system, wherein one of the third communication line and the fourth communication line that is connected to a communication line other than the communication line including the line length difference portion includes a correction portion that corrects the line length difference.

11. the wire length difference portion is provided within the first connector, The harness system according to claim 10 , wherein the compensation portion is provided in the second connector.

12. The harness system according to claim 10 or 11, wherein the first wire harness further includes a sheet-like holding member that holds the first communication line and the second communication line.

13. a wire harness that connects the first communication unit and the second communication unit so as to enable communication between them; a detection unit that detects degradation of communication performance; a determination unit that determines whether or not the communication is fraudulent based on the detection result of the detection unit, the wire harness includes a first communication line and a second communication line; An unauthorized connection prevention system, wherein at least one of the first communication line and the second communication line includes a correction unit that corrects the difference in line length between a communication line electrically connected to the first communication line and a communication line electrically connected to the second communication line.

14. The unauthorized connection prevention system according to claim 13 , further comprising a communication restriction unit that restricts communication in response to the determination unit determining that the communication is unauthorized.

15. An in-vehicle device mounted on a vehicle, a connector to which the wire harness is connected; a substrate on which electronic components are mounted; a first communication line and a second communication line for transmitting signals between the electronic component and the wire harness; At least one of the first communication line and the second communication line includes a line length difference portion that causes a line length difference between the first communication line and the second communication line.

16. The in-vehicle device according to claim 15 , wherein the wire length difference portion is provided inside the connector.

17. The in-vehicle device according to claim 15 , wherein the line length difference portion is provided on the substrate.