Signal transmission device, signal transmission system, and information providing method

Abstract

The signal transmission device of the present invention includes: a communication unit capable of performing differential transmission-based communication with an electronic device via differential wiring; and a signal processing unit that performs signal processing on the communication. The communication unit can receive communication signals transmitted from the electronic device via the differential wiring at a plurality of signal transmission speeds including at least a first signal transmission speed and a second signal transmission speed lower than the first signal transmission speed. The communication unit measures the amplitude of the communication signal received from the electronic device at the second signal transmission speed, and the signal processing unit detects a short circuit fault of the filter circuit based on the amplitude measured by the communication unit.

Description

Technical Field

[0001] The present invention relates to a signal transmission device, a signal transmission system, and an information providing method. Background Art

[0002] In recent years, in signal transmission between devices mounted in a vehicle, in order to reduce the weight and cost of a wiring harness, a transmission method called PoDL (Power over Data Lines) that uses twisted pair wires to achieve signal transmission and power supply has been proposed. In PoDL, filter circuits called PoDL filters are respectively mounted in the transmitting and receiving devices to separate the signal from the power supply, so that the signal and the power supply can flow superimposed in the twisted pair wires without adversely affecting the signal quality.

[0003] In the case of adopting PoDL, when the PoDL filter fails, the signal cannot be correctly transmitted, so it is necessary to reliably detect the failure of the PoDL filter.

[0004] As the background art related to the present invention, Patent Document 1 is known. In Patent Document 1, a system is disclosed in which electronic devices are connected by twisted pair wires and a differential signal and a power supply are transmitted superimposed in the twisted pair wires. In this system, a capacitor for DC cut-off is arranged on the signal line, and filter elements such as a common mode choke coil and an inductor are inserted on the power supply line as a PoDL filter. Thus, the signal and the power supply are separated according to the frequency range of the filter element.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: U.S. Patent No. 10,594,519 Specification Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] The technique of Patent Document 1 reduces the leakage of common mode noise from the circuit on the wiring circuit board to the twisted pair wires by arranging filter elements between the communication circuit and the twisted pair wires, and suppresses the propagation of the common mode noise picked up by the twisted pair wires to the circuit on the wiring circuit board. However, the technique of Patent Document 1 cannot detect the failure of the filter circuit used as the PoDL filter.

[0010] Technical Solution for Solving the Problems

[0011] The signal transmission device of the present invention is connected to an electronic device by differential wiring composed of a pair of wires, and includes: a communication unit capable of performing communication based on differential transmission between the differential wiring and the electronic device; and a signal processing unit that performs signal processing on the communication. The electronic device and the signal transmission device each have a power supply unit capable of supplying a power current via the differential wiring, and a filter circuit electrically connected between the differential wiring and the power supply unit. The communication unit can receive communication signals transmitted from the electronic device via the differential wiring at a plurality of signal transmission speeds including at least a first signal transmission speed and a second signal transmission speed lower than the first signal transmission speed. The communication unit measures the amplitude of the communication signal received from the electronic device at the second signal transmission speed. The signal processing unit detects a short circuit fault of the filter circuit based on the amplitude measured by the communication unit.

[0012] The signal transmission system of the present invention includes a first electronic device and a second electronic device connected to the first electronic device by differential wiring composed of a pair of wires. The first electronic device includes: a pair of first signal wirings respectively connected to the differential wiring; a first communication unit capable of performing communication based on differential transmission between the second electronic device via the first signal wiring and the differential wiring; a first power supply unit capable of supplying a power current via the differential wiring; and a first filter circuit having a pair of filter elements respectively connected between the pair of first signal wirings and the first power supply unit. The second electronic device includes: a pair of second signal wirings respectively connected to the differential wiring; a second communication unit that performs the communication with the first electronic device via the second signal wiring and the differential wiring; a second signal processing unit capable of performing signal processing on the communication; a second power supply unit capable of supplying the power current via the differential wiring; and a second filter circuit having a pair of filter elements respectively connected between the pair of second signal wirings and the second power supply unit. The first communication unit transmits communication signals at a plurality of signal transmission speeds including at least a first signal transmission speed and a second signal transmission speed lower than the first signal transmission speed. The second communication unit receives the communication signals transmitted from the first communication unit via the differential wiring, and measures the amplitude of the communication signal received at the second signal transmission speed. The second signal processing unit detects a short circuit fault of the first filter circuit or the second filter circuit based on the amplitude measured by the second communication unit.

[0013] The information providing method of the present invention uses the above signal transmission system, which is mounted on an automobile having an in-vehicle network and a communication device for wireless communication connected to the in-vehicle network. When the second signal processing unit detects the short-circuit fault, fault information about the short-circuit fault is sent from the second electronic device to the communication device via the in-vehicle network, and the fault information is sent to a server device disposed at a position different from that of the automobile through wireless communication performed by the communication device. The server device uses a pre-registered database to obtain fault object component information about the first filter circuit or the second filter circuit in which the short-circuit fault has occurred, and the server device inquires a repairer who repairs the automobile about whether repair is possible based on the fault object component information, and sends recommended repair information based on the result of the inquiry from the server device, and information about the repair of the short-circuit fault is provided to the user of the automobile based on the recommended repair information sent from the server device.

[0014] Effect of the Invention

[0015] According to the present invention, it is possible to detect a fault in a filter circuit used as a PoDL filter.

[0016] Problems, structures, and effects other than the above will be described in the following detailed description. Description of the Drawings

[0017] Figure 1 FIG. is a diagram showing the structure of a signal transmission system according to a first embodiment of the present invention.

[0018] Figure 2 FIG. is a diagram showing an example of the structure of an existing signal transmission system.

[0019] Figure 3 Table is a table showing the change status of a communication signal determined by the presence or absence of a short-circuit fault in a filter circuit.

[0020] Figure 4 FIG. is an explanatory diagram of loss compensation performed by a waveform equalization circuit.

[0021] Figure 5 FIG. is a diagram showing the structure of a signal transmission system according to a second embodiment of the present invention.

[0022] Figure 6 FIG. is a flowchart showing the process of a test mode according to a third embodiment of the present invention.

[0023] Figure 7 FIG. is a diagram showing the structure of a signal transmission system according to a fourth embodiment of the present invention.

[0024] Figure 8This is a diagram showing the structure of a signal transmission system according to the fifth embodiment of the present invention.

[0025] Figure 9 This is a table showing the relationship between the occurrence location of a short - circuit fault in a PoDL filter and the change in the received signal in a test mode.

[0026] Figure 10 This is a flowchart showing the process of a test mode according to the sixth embodiment of the present invention.

[0027] Figure 11 This is a flowchart showing the process of a test mode according to the seventh embodiment of the present invention.

[0028] Figure 12 This is a flowchart showing the process of a test mode according to the eighth embodiment of the present invention.

[0029] Figure 13 This is a diagram showing the connection structure of a power supply unit according to the ninth embodiment of the present invention.

[0030] Figure 14 This is a diagram showing the structure of a signal transmission system according to the tenth embodiment of the present invention.

[0031] Figure 15 This is a diagram showing the structure of a vehicle - mounted system including a signal transmission system according to the eleventh embodiment of the present invention.

[0032] Figure 16 This is a diagram showing the structure of a vehicle - mounted system including a signal transmission system according to the twelfth embodiment of the present invention.

[0033] Figure 17 This is a diagram showing the structure of an information - providing system according to the thirteenth embodiment of the present invention.

[0034] Figure 18 This is a diagram showing the structure of an information - providing system according to the fourteenth embodiment of the present invention. Detailed Embodiments

[0035] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description and the drawings are examples for explaining the present invention, and omissions and simplifications have been appropriately made for clarity. The present invention can also be implemented in various other ways. Unless otherwise specifically limited, each component can be single or multiple.

[0036] The positions, sizes, shapes, ranges, etc. of the components shown in the drawings do not necessarily represent the actual positions, sizes, shapes, ranges, etc. in order to make the invention easier to understand. Therefore, the present invention is not necessarily limited to the positions, sizes, shapes, ranges, etc. disclosed in the drawings.

[0037] When there are multiple constituent elements having the same or similar functions, they are sometimes described by attaching different suffixes to the same reference numeral. However, when it is not necessary to distinguish between the multiple constituent elements, the suffixes are sometimes omitted in the description.

[0038] In addition, in the following description, there are cases where the processing performed by the execution program is described. However, the program is executed by a processor (such as a CPU or GPU), and appropriate use of storage resources (such as a memory) and / or interface devices (such as a communication port) is made to perform the specified processing. Therefore, the subject of the processing can also be changed to a processor. Similarly, the subject of the processing performed by the execution program can also be a controller, device, system, computer, or node having a processor. The subject of the processing performed by the execution program only needs to be an arithmetic unit and can include a dedicated circuit (such as an FPGA or ASIC) that performs specific processing.

[0039] The program can be installed from a program source to a device such as a computer. The program source can be, for example, a program distribution server or a storage medium readable by a computer. When the program source is a program distribution server, the program distribution server can include a processor and a storage resource for storing the program to be distributed, and the processor of the program distribution server distributes the program to be distributed to other computers. In addition, in the following description, two or more programs can be implemented as one program, or one program can be implemented as two or more programs.

[0040] (First Embodiment)

[0041] Figure 1 This is a diagram showing the structure of the signal transmission system according to the first embodiment of the present invention. In Figure 1 In the shown signal transmission system 100, the electronic device 1 and the signal transmission device 2 are interconnected via a differential wiring 5, and are configured to perform signal transmission and power supply between the electronic device 1 and the signal transmission device 2 via the differential wiring 5.

[0042] The differential wiring 5 is a communication cable for differential transmission composed of a pair of wires, and is formed of, for example, twisted pair. In addition, the following description is made assuming that signal transmission and power supply are performed from the electronic device 1 to the signal transmission device 2, the electronic device 1 is the sender of the communication signal and the supplier of the power source, and the signal transmission device 2 is the receiver of the communication signal and the recipient of the power supply. However, the combination of the signal transmission direction and the power supply direction is not limited to this. For example, conversely, the signal transmission device 2 can be the sender of the communication signal and the supplier of the power source, the electronic device 1 can be the receiver of the communication signal and the recipient of the power supply, and the signal transmission direction and the power supply direction can also be different.

[0043] The signal transmission device 2 is an electronic device that realizes various functions through communication with the electronic device 1 and other electronic devices. For example, when using an ECU (Electronic Control Unit) for image processing for autonomous driving as the electronic device 1, the electronic device 1 receives an image signal sent from a camera installed in the vehicle and performs various image processes related to the autonomous driving of the vehicle based on the received image signal. Then, the image processing result, such as an object recognition result, is sent to the signal transmission device 2 via the differential wiring 5. The signal transmission device 2 performs processing related to vehicle control based on the image processing result received from the electronic device 1.

[0044] The electronic device 1 includes a communication unit 11, a power supply unit 12, a filter circuit 13, capacitors 14P and 14N, signal wirings 15P and 15N, and a connector 16. The signal transmission device 2 includes a communication unit 21, a power supply unit 22, a filter circuit 23, capacitors 24P and 24N, signal wirings 25P and 25N, a connector 26, and a signal processing unit 27.

[0045] The communication unit 11 includes a communication control unit 110 and a differential transmission circuit 111. The differential transmission circuit 111 is connected to the signal wirings 15P and 15N via the capacitors 14P and 14N, respectively. The signal wirings 15P and 15N are connected to a pair of wires constituting the differential wiring 5 via the connector 16, respectively. The differential transmission circuit 111 outputs communication signals with opposite polarities to the signal wiring 15P and the signal wiring 15N, respectively, based on the communication data input from the communication control unit 110. The communication signals output from the differential transmission circuit 111 to the signal wirings 15P and 15N are, for example, serial signals representing data "1" and "0" using the voltage difference, and the voltage changes at a specified period. The signal transmission speed of the communication signal is determined corresponding to the period of the voltage change, and the shorter the period, the faster the signal transmission speed. Thus, the communication unit 11 can perform communication based on differential transmission with the signal transmission device 2 via the signal wirings 15P and 15N and the differential wiring 5.

[0046] The communication unit 21 includes a reception processing unit 210, a differential reception circuit 211, and a waveform equalization circuit 212. The differential reception circuit 211 is connected to the signal wirings 25P and 25N via the capacitors 24P and 24N, respectively. The signal wirings 25P and 25N are connected to a pair of wires constituting the differential wiring 5 via the connector 26, respectively.

[0047] For the communication unit 21, communication signals transmitted from the electronic device 1 to the signal transmission device 2 via the differential wiring 5 are input via the connector 26, signal wirings 25P and 25N, and capacitors 24P and 24N. The differential reception circuit 211 receives the communication signals input to the communication unit 21 and outputs them to the waveform equalization circuit 212. The waveform equalization circuit 212 compensates for signal attenuation caused by the differential wiring 5 by adjusting the waveform of the communication signals received by the differential reception circuit 211 in accordance with the frequency characteristics of the differential wiring 5. The function of such a waveform equalization circuit 212 is called an equalizer function, and since it can be implemented with a well-known circuit configuration, its detailed description is omitted.

[0048] The communication signals adjusted by the waveform equalization circuit 212 are output to the reception processing unit 210. The reception processing unit 210 decodes the communication data included in the received communication signals and measures the amplitude of the communication signals, and outputs this information to the signal processing unit 27. Thus, the communication unit 21 can perform communication based on differential transmission with the electronic device 1 via the signal wirings 25P and 25N and the differential wiring 5.

[0049] The signal processing unit 27 is a part that performs various signal processes based on the communication data decoded from the communication signals by the reception processing unit 210, and is implemented using, for example, a microcomputer that executes a prescribed program or an integrated circuit such as an LSI, FPGA, or ASIC. The signal processing unit 27 has a filter state determination unit 270 as a part of its function. The filter state determination unit 270 detects failures of the filter circuits 13 and 23 based on the amplitude of the communication signals measured by the reception processing unit 210 and performs processing corresponding to the detection result. In addition, details of the method for detecting failures of the filter circuits 13 and 23 performed by the filter state determination unit 270 are described later.

[0050] In the communication unit 11 of the electronic device 1, the communication control unit 110 has a function of changing the signal transmission speed of the communication signals transmitted from the electronic device 1 to the signal transmission device 2 via the differential wiring 5. For example, by changing the communication speed of the communication data output from the communication control unit 110 to the differential transmission circuit 111, the period of the communication signals output from the differential transmission circuit 111 to the signal wirings 15P and 15N is changed, thereby changing the signal transmission speed of the communication signals. At this time, in the communication unit 21 of the signal transmission device 2, in accordance with the change in the signal transmission speed of the communication signals transmitted from the electronic device 1, the operations of the differential reception circuit 211, the waveform equalization circuit 212, and the reception processing unit 210 are changed as needed. Thus, the communication unit 21 can receive communication signals transmitted from the electronic device 1 at different signal transmission speeds via the differential wiring 5, and can perform decoding of communication data and measurement of the amplitude of the communication signals in the communication unit 21.

[0051] In the electronic device 1, the power supply unit 12 generates a DC power supply current Id using the externally input power supply voltage Vin, and outputs the generated power supply current Id from the power supply terminal V to the differential wiring 5 via the filter circuit 13, the signal wiring 15P, and the connector 16. Thus, the power supply current Id is superimposed on the communication signal in the differential wiring 5, and the power supply current Id flows in the direction from the electronic device 1 to the signal transmission device 2, supplying the power supply current Id to the signal transmission device 2.

[0052] The power supply current Id supplied from the electronic device 1 to the signal transmission device 2 via the differential wiring 5 is input to the power supply terminal V of the power supply unit 22 via the connector 26, the signal wiring 25P, and the filter circuit 23. The power supply unit 22 generates a power supply voltage Vout using the input power supply current Id and outputs it to each part of the signal transmission device 2 including the communication unit 21 and the signal processing unit 27. Thus, the power supply current Id supplied from the electronic device 1 is distributed to the communication unit 21 and the signal processing unit 27.

[0053] In addition, as described above, when the power supply current Id flows from the power supply unit 12 of the electronic device 1 to the power supply unit 22 of the signal transmission device 2, the corresponding ground current Ig flows in the direction opposite to that of the power supply current Id, that is, from the power supply unit 22 of the signal transmission device 2 to the power supply unit 12 of the electronic device 1. The ground current Ig is output from the ground terminal G of the power supply unit 22 to the differential wiring 5 via the filter circuit 23, the signal wiring 25N, and the connector 26, and is superimposed on the communication signal in the differential wiring 5. In addition, the ground current Ig input to the electronic device 1 is input to the ground terminal G of the power supply unit 12 via the connector 16, the signal wiring 15N, and the filter circuit 13.

[0054] The filter circuit 13 is electrically connected between the differential wiring 5 and the power supply unit 12. The filter circuit 13 is composed of an inductor L1 connected between the signal wiring 15P and the power supply terminal V of the power supply unit 12 and an inductor L2 connected between the signal wiring 15N and the ground terminal G of the power supply unit 12 as filter elements. The filter circuit 13 functions as a low-pass filter (PoDL filter) that allows the power supply current Id output from the power supply unit 12 and the ground current Ig input to the power supply unit 12 to pass through and shields the communication signal transmitted from the electronic device 1 to the signal transmission device 2 via the differential wiring 5. In the filter circuit 13, the inductor L1 and the inductor L2 function as filter elements having the same frequency characteristics.

[0055] The filter circuit 23 is electrically connected between the differential wiring 5 and the power supply unit 22. The filter circuit 23 is composed of an inductor L3 connected between the signal wiring 25P and the power supply terminal V of the power supply unit 22 and an inductor L4 connected between the signal wiring 25N and the ground terminal G of the power supply unit 22 as filter elements. The filter circuit 23 functions as a low-pass filter (PoDL filter) that allows the power supply current Id input to the power supply unit 22 and the ground current Ig output from the power supply unit 12 to pass through, and shields the communication signal transmitted from the electronic device 1 to the signal transmission device 2 via the differential wiring 5. In the filter circuit 23, the inductor L3 and the inductor L4 function as filter elements having the same frequency characteristics.

[0056] In addition, Figure 1 in the example of, the filter circuit 13 is composed of two inductors L1 and L2, and the filter circuit 23 is composed of two inductors L3 and L4. However, the number of inductors constituting the filter circuits 13 and 23 is not limited to this, and the filter circuits 13 and 23 may be composed of three or more inductors. In addition, the filter circuits 13 and 23 may be composed of elements other than inductors. As long as a PoDL filter that allows the power supply current Id and the ground current Ig to pass through and shields the communication signal can be realized, the filter circuits 13 and 23 can be composed of filters in any number and manner.

[0057] The capacitors 14P and 14N are respectively connected between the signal wirings 15P and 15N and the communication unit 11, and function as a high-pass filter that allows the communication signal transmitted from the electronic device 1 to the signal transmission device 2 via the differential wiring 5 to pass through, and shields the power supply current Id output from the power supply unit 12 and the ground current Ig input to the power supply unit 12. The capacitors 24P and 24N are respectively connected between the signal wirings 25P and 25N and the communication unit 21, and function as a high-pass filter that allows the communication signal transmitted from the electronic device 1 to the signal transmission device 2 via the differential wiring 5 to pass through, and shields the power supply current Id input to the power supply unit 22 and the ground current Ig output from the power supply unit 12.

[0058] Next, for the fault detection method of the filter circuits 13 and 23 in the signal transmission system 100 of the first embodiment of the present invention, through comparison with an existing signal transmission system, reference is made to Figure 2 , 3 and 4 for description.

[0059] Figure 2 shows a structural example of an existing signal transmission system 100Z. Figure 2 The signal transmission system 100Z shown in is the same as Figure 1The signal transmission system 100 shown also has the electronic device 1Z and the signal transmission device 2Z connected to each other via the differential wiring 5. Compared with the signal transmission system 100 of Figure 1 the signal transmission system 100, the communication unit 11Z of the electronic device 1Z has a communication control unit 110Z that does not have a function of changing the communication signal transmission speed, the communication unit 21Z of the signal transmission device 2Z has a reception processing unit 210Z that does not have a function of measuring the amplitude of the communication signal, and the signal processing unit 27Z of the signal transmission device 2Z does not have a filter state determination unit 270.

[0060] In Figure 2 the structure of the signal transmission system 100Z, as described in the following reference Figure 3 it is difficult to detect a failure of the filter circuits 13 and 23.

[0061] As Figure 1 described, the PoDL filter, that is, the filter circuits 13 and 23 are composed of inductors L1 and L2 respectively connected between the power supply unit 12 and the signal wirings 15P and 15N, and inductors L3 and L4 respectively connected between the power supply unit 22 and the signal wirings 25P and 25N. As failures of the filter circuits 13 and 23, two cases of an open circuit failure and a short circuit failure of any one of the inductors L1 to L4 are considered. Here, when an open circuit failure occurs in any one of the inductors L1 to L4, the current path from the power supply current Id to the ground current Ig is cut off, and the power supply from the electronic device 1Z to the signal transmission device 2Z stops. Therefore, by detecting this, it is possible to easily detect that a failure has occurred in any one of the filter circuits 13 and 23. On the other hand, when a short circuit failure occurs in any one of the inductors L1 to L4, the function of the low-pass filter that shields the communication signal transmitted from the electronic device 1Z to the signal transmission device 2Z via the differential wiring 5 is lost, so although it affects the communication signal, the power supply from the electronic device 1Z to the signal transmission device 2Z is carried out without problems. Thus, in order to reliably detect a failure of the filter circuits 13 and 23, whether it is possible to detect a short circuit failure of the inductors L1 to L4 based on the change of the communication signal is the key point.

[0062] Figure 3 is a table showing the state of the change of the communication signal determined by the presence or absence of a short circuit failure of the filter circuit 13. Figure 3In the table, the first row shows an example of the transmission waveforms of each observation point of the electronic device 1Z and the signal transmission device 2Z during normal transmission, that is, when the filter circuit 13 of the electronic device 1Z has no fault. The second row shows an example of the transmission waveforms of each observation point of the electronic device 1Z and the signal transmission device 2Z when a short-circuit fault occurs in the inductor L1 on the power supply side of the filter circuit 13 of the electronic device 1Z. Specifically, examples of the power supply potential (DC voltage level of the power supply current Id), P-side waveform (voltage waveform of the signal wiring 15P during communication signal transmission), N-side waveform (voltage waveform of the signal wiring 15N during communication signal transmission), differential amplitude on the transmitting end side (potential difference between the signal wiring 15P and the signal wiring 15N during communication signal transmission), differential waveform on the receiving end side (potential difference between the signal wiring 25P and the signal wiring 25N during communication signal reception), and equalized received waveform (output waveform of the waveform equalization circuit 212).

[0063] According to Figure 3 the table, the power supply potential does not change due to the presence or absence of a short-circuit fault in the inductor L1. Therefore, it can be seen that the fault of the inductor L1 cannot be detected based on the voltage change of the power supply current Id. On the other hand, when a short-circuit fault occurs in the inductor L1, the potential of the P-side waveform is fixed, and thus the differential amplitude on the transmitting end side becomes half (-6 dB). However, this is less than the loss compensation amount (about 12 dB to 25 dB) of the general equalizer function of the waveform equalization circuit 212, which is equivalent to the attenuation amount that can be sufficiently compensated by the waveform equalization circuit 212. Therefore, considering the error of the attenuation amount caused by the differential wiring 5, etc., it can be seen that it is difficult to correctly detect the amplitude difference of the communication signal caused by the presence or absence of a short-circuit fault in the inductor L1 using the equalized received waveform output from the waveform equalization circuit 212.

[0064] Figure 4 is an explanatory diagram of the loss compensation performed by the waveform equalization circuit 212. During normal communication when transmitting a communication signal at high speed, as Figure 4 shown by the solid line in, as the frequency (transmission speed) of the communication signal increases, the loss of the channel including the differential wiring 5 increases. The difference in the loss amounts of such frequencies affects the communication signal waveform, and thus inter-symbol interference occurs in the communication signal, deteriorating the quality of the communication signal. Therefore, in the waveform equalization circuit 212, in order to reduce such deterioration of the communication signal quality, as Figure 4 shown by the dashed line in, the transmission frequency range of the communication signal is used as the effective frequency range of the equalizer function, and loss compensation is performed to make the loss amount in this frequency range flat on the frequency axis. In addition, Figure 4In [the figure], an example is illustrated in which the waveform equalization circuit 212 performs loss compensation in a direction of reducing loss on the high-frequency side. Conversely, by increasing the loss on the low-frequency side where the loss amount is small and flattening on the frequency axis, loss compensation can also be performed. In either case, the principle is the same.

[0065] As described above, with Figure 2 the structure of the existing signal transmission system 100Z shown, it is difficult to detect a short-circuit fault of the inductor L1 in the filter circuit 13 according to a change in the received waveform. The same applies when a short-circuit fault occurs in other inductors L2 to L4.

[0066] Then, Figure 1 in the signal transmission system 100 according to the first embodiment of the present invention shown, in a test mode for fault detection, the communication control unit 110 of the electronic device 1 adjusts the signal transmission speed of the communication signal to a low speed so that it becomes a lower frequency side than the effective frequency range of the equalizer function in which the waveform equalization circuit 212 adjusts the waveform of the communication signal to compensate for the attenuation caused by the differential wiring 5, that is, a frequency range where the loss compensation ability of the equalizer is insufficient. At this time, assuming that the signal transmission speed before adjustment in normal times is T1 and the signal transmission speed after adjustment in the test mode is T2, T1 > T2. Thus, as the communication signal from the electronic device 1 to the signal transmission device 2, a low-speed signal for short-circuit fault detection shown is output via the differential wiring 5. Figure 4 The low-speed signal for short-circuit fault detection shown.

[0067] Then, the receiving processing unit 210 of the signal transmission device 2 measures the amplitude of the communication signal with the signal transmission speed T2 received by the differential receiving circuit 211, and the filter state determination unit 270 compares the measurement result with the amplitude information of the received signal in normal times. In addition, the amplitude information of the received signal in normal times is set in advance in the filter state determination unit 270 as the amplitude of the communication signal with the signal transmission speed T2 when no short-circuit fault occurs in the filter circuits 13 and 23. As a result, when the amplitude of the received communication signal is about half (-6 dB) of the amplitude in normal times, it is determined that a short-circuit fault has occurred in any one of the inductors L1 to L4 in the filter circuits 13 and 23.

[0068] The signal transmission system 100 according to the first embodiment of the present invention can reliably detect a short-circuit fault in the filter circuits 13 and 23 by performing the above-described processing by the electronic device 1 and the signal transmission device 2, respectively. Further, when measuring the amplitude of the received communication signal in the signal transmission device 2, it is preferable to adjust the signal transmission speed of the communication signal transmitted from the electronic device 1 such that the frequency of the communication signal at the adjusted signal transmission speed T2 is equal to or lower than 1 / 20 of the fundamental frequency of the communication signal at the normal signal transmission speed T1.

[0069] According to the first embodiment of the present invention described above, the following effects can be obtained.

[0070] (1) The signal transmission device 2 is connected to the electronic device 1 by a differential wiring 5 composed of a pair of electric wires, and includes a communication unit 21 that performs communication based on differential transmission with the electronic device 1 via the differential wiring 5, and a signal processing unit 27 that performs signal processing related to the communication. The electronic device 1 and the signal transmission device 2 each have a power supply unit 12, 22 that supplies a power supply current Id via the differential wiring 5, and filter circuits 13, 23 that are electrically connected between the differential wiring 5 and the power supply units 12, 22. The communication unit 21 can receive communication signals transmitted from the electronic device 1 at various signal transmission speeds including at least the signal transmission speed T1 and a signal transmission speed T2 lower than the signal transmission speed T1 via the differential wiring 5. The communication unit 21 measures the amplitude of the communication signal received from the electronic device 1 at the signal transmission speed T2 using a reception processing unit 210. The signal processing unit 27 detects a short-circuit fault in the filter circuits 13 and 23 based on the amplitude measured by the communication unit 21 using a filter state determination unit 270. Because of this, it is possible to detect a fault in the filter circuits 13 and 23 used as PoDL filters.

[0071] (2) The power supply unit 12 included in the electronic device 1 applies a prescribed potential difference between the pair of electric wires of the differential wiring 5 to supply the power supply current Id to the signal transmission device 2. The power supply unit 22 included in the signal transmission device 2 distributes the power supply current Id supplied from the electronic device 1 to the communication unit 21 and the signal processing unit 27. Because of this, it is possible to supply power to the signal transmission device 2 from the electronic device 1 via the differential wiring 5 and operate each part of the signal transmission device 2 using this power supply.

[0072] (3) The communication unit 21 has an equalizer function in a waveform equalization circuit 212 that adjusts the waveform of the communication signal within a prescribed effective frequency range to compensate for attenuation caused by the differential wiring 5. The signal transmission speed T2 is a signal transmission speed at which the frequency of the communication signal is lower than the frequency of the effective frequency range of this equalizer function. Because of this, it is possible to correctly measure the amplitude of the communication signal.

[0073] (4) The signal transmission speed T2 is preferably a signal transmission speed at which the frequency of the communication signal is 1 / 20 or less of the fundamental frequency of the communication signal with the signal transmission speed T1. In this way, the signal transmission speed can be adjusted to an appropriate value such that the frequency of the communication signal is lower than the effective frequency range of the equalizer function.

[0074] (5) The signal transmission system 100 includes an electronic device 1 and a signal transmission device 2 which is an electronic device connected to the electronic device 1 by differential wiring 5 composed of a pair of electric wires. The electronic device 1 includes a pair of signal wirings 15P and 15N respectively connected to the differential wiring 5, a communication unit 11 that performs communication based on differential transmission with the signal transmission device 2 via the signal wirings 15P, 15N and the differential wiring 5, a power supply unit 12 that supplies a power supply current Id via the differential wiring 5, and a filter circuit 13 having a pair of filter elements, i.e., inductors L1 and L2, respectively connected between the pair of signal wirings 15P, 15N and the power supply unit 12. The signal transmission device 2 includes a pair of signal wirings 25P and 25N respectively connected to the differential wiring 5, a communication unit 21 that communicates with the electronic device 1 via the signal wirings 25P, 25N and the differential wiring 5, a signal processing unit 27 that performs signal processing on the communication, a power supply unit 22 that supplies a power supply current Id via the differential wiring 5, and a filter circuit 23 having a pair of filter elements, i.e., inductors L3 and L4, respectively connected between the pair of signal wirings 25P, 25N and the power supply unit 22. The communication unit 11 transmits communication signals at a plurality of signal transmission speeds including at least the signal transmission speed T1 and a signal transmission speed T2 lower than the signal transmission speed T1. The communication unit 21 receives the communication signals transmitted from the communication unit 1 via the differential wiring 5 using a differential reception circuit 211, and measures the amplitude of the communication signals received at the signal transmission speed T2 using a reception processing unit 210. The signal processing unit 27 detects a short-circuit failure of the filter circuit 13 or the filter circuit 23 based on the amplitude measured by the communication unit 21 using a filter state determination unit 270. Because of this, in the signal transmission system 100 composed of the electronic device 1 and the signal transmission device 2, a short-circuit failure of the filter circuits 13 and 23 respectively used as PoDL filters can be detected.

[0075] (Second Embodiment)

[0076] Next, a signal transmission device and a signal transmission system according to a second embodiment of the present invention will be described. In the above-described first embodiment, an example was described in which the electronic device 1 and the signal transmission device 2 are connected to each other via the differential wiring 5, and signal transmission and power supply are performed via the differential wiring 5 in the direction from the electronic device 1 to the signal transmission device 2. In contrast, in the present embodiment, an example will be described in which the electronic device 1A and the signal transmission device 2A are connected to each other via the differential wiring 5, signal transmission is performed via the differential wiring 5 in the direction from the electronic device 1A to the signal transmission device 2A, and power supply is performed via the differential wiring 5 in the direction from the signal transmission device 2A to the electronic device 1A.

[0077] Figure 5 FIG. is a diagram showing the structure of a signal transmission system according to a second embodiment of the present invention. Figure 5 In the shown signal transmission system 100A, the electronic device 1A and the signal transmission device 2A have the same structure as the electronic device 1 and the signal transmission device 2 of the first embodiment described Figure 1 except that they respectively have power supply units 12A and 22A instead of the power supply units 12 and 22.

[0078] In the present embodiment, the power supply unit 22A generates a DC power supply current Id using an externally input power supply voltage Vin, and outputs the generated power supply current Id to the differential wiring 5 from the power supply terminal V via the filter circuit 23, the signal wiring 25P, and the connector 26. As a result, the power supply current Id is superimposed on the communication signal in the differential wiring 5, and the power supply current Id flows in the direction from the signal transmission device 2A to the electronic device 1A, supplying the power supply current Id to the electronic device 1A.

[0079] The power supply current Id supplied to the electronic device 1A from the signal transmission device 2A via the differential wiring 5 is input to the power supply terminal V of the power supply unit 12A via the connector 16, the signal wiring 15P, and the filter circuit 13. The power supply unit 12A generates a power supply voltage Vout using the input power supply current Id and outputs it to each part of the electronic device 1A including the communication unit 11. As a result, the power supply current Id supplied from the signal transmission device 2A is distributed to the communication unit 11.

[0080] Further, as described above, when the power supply current Id flows from the power supply unit 22A of the signal transmission device 2A to the power supply unit 12A of the electronic device 1A, the corresponding ground current Ig flows in the opposite direction to the power supply current Id, that is, from the power supply unit 12A of the electronic device 1A to the power supply unit 22A of the signal transmission device 2A. The ground current Ig is output from the ground terminal G of the power supply unit 12A to the differential wiring 5 via the filter circuit 13, the signal wiring 15N, and the connector 16, and is superimposed on the communication signal in the differential wiring 5. Further, the ground current Ig input to the signal transmission device 2A is input to the ground terminal G of the power supply unit 22A via the connector 26, the signal wiring 25N, and the filter circuit 23.

[0081] According to the second embodiment of the present invention described above, the power supply unit 22A included in the signal transmission device 2A applies a predetermined potential difference between a pair of wires of the differential wiring 5 to supply the power supply current Id to the electronic device 1A. The power supply unit 12A included in the electronic device 1A distributes the power supply current Id supplied from the signal transmission device 2A to the communication unit 11. Because of this, power can be supplied from the signal transmission device 2A to the electronic device 1A via the differential wiring 5, and each part of the electronic device 1A can be operated using this power.

[0082] (Third Embodiment)

[0083] Next, a third embodiment of the present invention will be described. In this embodiment, an example of a process of a test mode for detecting a short circuit failure of the PoDL filter will be described. Further, in this embodiment, an example of a case where the test mode is implemented in the signal transmission system 100 described in the first embodiment will be described. However, when the test mode is implemented in the signal transmission system 100A described in the second embodiment, the test mode can also be implemented by the same process.

[0084] Figure 6 FIG. is a flowchart showing a process of a test mode according to the third embodiment of the present invention. In step S101, the signal transmission system 100 uses the communication control unit 110 of the electronic device 1 to switch the signal transmission speed of the communication signal from the normal signal transmission speed T1 to the low signal transmission speed T2, and transfers to the low-speed signal transmission mode for testing.

[0085] Next, in step S102, the signal transmission system 100 uses the communication unit 21 of the signal transmission device 2 to receive the communication signal transmitted from the electronic device 1 at the signal transmission speed T2, and measures the amplitude of the received signal in the reception processing unit 210.

[0086] In step S103, the signal transmission system 100 uses the filter state determination unit 270 of the signal transmission device 2 to compare the amplitude of the received signal measured in step S102 with the amplitude of the received signal in the normal state set in advance, and determines whether the amplitude of the measured received signal is about 50% of that in the normal state. As a result, when it is determined that the amplitude of the measured received signal has decreased to about 50% of that in the normal state, in step S104, an alarm notification indicating that a short-circuit fault has occurred in either the PoDL filter, i.e., the filter circuits 13 or 23, is given. In addition, the alarm notification of the short-circuit fault can be given to the user of the signal transmission system 100 or the upper-level system carrying it by any method such as outputting a prescribed sound or image, etc.

[0087] When the alarm notification is given in step S104, or when it is determined in step S103 that the amplitude of the measured received signal has not decreased to about 50% of that in the normal state, the process ends Figure 6 of the test mode shown in the flowchart.

[0088] (Fourth Embodiment)

[0089] Next, the signal transmission device and the signal transmission system according to the fourth embodiment of the present invention will be described.

[0090] Figure 7 is a diagram showing the structure of the signal transmission system according to the fourth embodiment of the present invention. Figure 7 In the signal transmission system 100B shown, the electronic device 1 has the same structure as the electronic device 1 in the first embodiment described in Figure 1 In addition, the signal transmission device 2B has the same structure as the signal transmission device 2 in the first embodiment described in Figure 1 except that it further has a storage device 28.

[0091] In the present embodiment, in the storage device 28 of the signal transmission device 2B, amplitude information on the amplitude of the communication signal in the normal state where no short-circuit fault has occurred in the filter circuits 13 and 23 is stored. The filter state determination unit 270 reads the amplitude information stored in the storage device 28 and compares it with the amplitude of the communication signal of the signal transmission speed T2 received by the differential reception circuit 211 and measured by the reception processing unit 210. As a result, similar to the first embodiment, when the amplitude of the received communication signal is about half (-6 dB) of the amplitude in the normal state, it is determined that a short-circuit fault has occurred in one of the inductors L1 to L4 in the filter circuits 13 and 23.

[0092] In the storage device 28, it is preferable to store the amplitude information of the received signal in a normal state by combining information such as the amplitude of the transmission signal and / or the signal transmission speed, and the loss of the differential wiring 5. In addition, the loss information of the differential wiring 5 can be represented by the loss amount, or can be information indicating the loss characteristics of the differential wiring 5, such as the loss amount per unit length and the length information. Alternatively, the storage device 28 can store information capable of determining the loss amount of the differential wiring 5, such as the model number, etc.

[0093] Furthermore, for each parameter such as the amplitude of the transmission signal, the signal transmission speed, and the loss of the differential wiring 5, the storage device 28 can also store the amplitude information corresponding to a plurality of combinations that are different from each other in these parameter values. That is, when the amplitude of the transmission signal, the signal transmission speed, and the loss of the differential wiring 5 change respectively, the amplitude of the received signal also changes correspondingly to these changes. Therefore, in order to correctly detect the short - circuit fault of the filter circuits 13 and 23, it is necessary to consider the combination of these three parameter values and compare the amplitude measured from the received signal with the amplitude in a normal state. Thus, for various combinations of the above three parameter values, the storage device 28 stores the amplitude information in a normal state, and reads the amplitude information of the combination that matches the specifications of the signal transmission system 100B from the storage device 28 for the determination of the filter fault by the filter state determination unit 270. In this way, even when the specifications of the signal transmission system 100B change in various ways, the short - circuit faults of the filter circuits 13 and 23 can be correctly detected.

[0094] According to the fourth embodiment of the present invention described above, the signal transmission device 2B has a storage device 28 that stores amplitude information regarding the amplitude of the communication signal when the filter circuits 13 and 23 do not have a short - circuit fault. The signal processing unit 27 detects the short - circuit faults of the filter circuits 13 and 23 based on the amplitude measured by the communication unit 21 and the amplitude information stored in the storage device 28. Thereby, the short - circuit faults of the filter circuits 13 and 23 can be correctly detected.

[0095] (Fifth Embodiment)

[0096] Next, the signal transmission device and the signal transmission system of the fifth embodiment of the present invention will be described. In this embodiment, an example in which the electronic device 1C and the signal transmission device 2C connected via the differential wiring 5 perform two - way communication with each other will be described. In addition, the electronic device 1C and the signal transmission device 2C of this embodiment respectively correspond to the electronic device 1 and the signal transmission device 2 described in the first embodiment, and a part of their structures are different respectively. Hereinafter, the electronic device 1C and the signal transmission device 2C will be described centering on the differences from the first embodiment.

[0097] Figure 8This is a diagram showing the structure of a signal transmission system according to a fifth embodiment of the present invention. Figure 8 In the shown signal transmission system 100C, the electronic device 1C has the same structure as the electronic device 1 of the first embodiment described Figure 1 in except that it has a communication unit 11C instead of the communication unit 11 and also has a signal processing unit 17. In addition, the signal transmission device 2C has the same structure as the signal transmission device 2 of the first embodiment described Figure 1 in except that it has a communication unit 21C instead of the communication unit 21.

[0098] In addition to the communication control unit 110 and the differential transmission circuit 111 described in the first embodiment, the communication unit 11C further includes a reception processing unit 112, a differential reception circuit 113, and a waveform equalization circuit 114. The differential reception circuit 113 is connected to the signal wirings 15P and 15N via capacitors 14P and 14N, respectively. In addition to the reception processing unit 210, the differential reception circuit 211, and the waveform equalization circuit 212 described in the first embodiment, the communication unit 21C further includes a communication control unit 213 and a differential transmission circuit 214. The differential transmission circuit 214 is connected to the signal wirings 25P and 25N via capacitors 24P and 24N, respectively.

[0099] Based on the communication data input from the communication control unit 213, the differential transmission circuit 214 outputs communication signals with opposite polarities to the signal wirings 25P and 25N, respectively, in the same manner as the differential transmission circuit 111 of the electronic device 1C. The communication signal is transmitted from the signal transmission device 2C to the electronic device 1C via the differential wiring 5, and is input to the communication unit 11C via the connector 16, the signal wirings 15P and 15N, and the capacitors 14P and 14N. In addition, similar to the communication control unit 110 of the electronic device 1C, the communication control unit 213 has a function of changing the signal transmission speed of the communication signal transmitted from the signal transmission device 2C.

[0100] The differential reception circuit 113 receives the communication signal input to the communication unit 11C and outputs it to the waveform equalization circuit 114. The waveform equalization circuit 114 has an equalizer function similar to the waveform equalization circuit 212 of the signal transmission device 2C, and compensates for the signal attenuation caused by the differential wiring 5 by adjusting the waveform of the communication signal received by the differential reception circuit 113 according to the frequency characteristics of the differential wiring 5. The communication signal adjusted by the waveform equalization circuit 114 is output to the reception processing unit 112. The reception processing unit 112 decodes the communication data included in the received communication signal, measures the amplitude of the communication signal, and outputs this information to the signal processing unit 17.

[0101] The signal processing unit 17, like the signal processing unit 27 of the signal transmission device 2C, is a part that performs various signal processes based on the communication data decoded from the communication signal by the reception processing unit 112. For example, it is implemented using a microcomputer that executes a prescribed program, or an integrated circuit such as an LSI, an FPGA, or an ASIC. The signal processing unit 17 has a filter state determination unit 170 as a part of its functions. The filter state determination unit 170, like the filter state determination unit 270 of the signal transmission device 2C, detects a failure of the filter circuits 13 and 23 based on the amplitude of the communication signal measured by the reception processing unit 112, and performs processing corresponding to the detection result.

[0102] According to the fifth embodiment of the present invention described above, communication can be performed bidirectionally between the electronic device 1C and the signal transmission device 2C. Furthermore, filter state determination units 170 and 270 are respectively provided in the electronic device 1C and the signal transmission device 2C, so that failure detection of the filter circuits 13 and 23 can be performed in either communication direction.

[0103] (Sixth Embodiment)

[0104] Next, a signal transmission device and a signal transmission system according to a sixth embodiment of the present invention will be described. In this embodiment, an example of determining in which device a short-circuit failure of a PoDL filter has occurred when the short-circuit failure of the PoDL filter is detected will be described. In addition, since this embodiment assumes bidirectional communication, the signal transmission system 100C described in the fifth embodiment will be used to describe an example of the case where a short-circuit failure of the PoDL filter is detected. Figure 8 The table shows the relationship between the occurrence location of the short-circuit failure in the PoDL filter and the change in the received signal in the test mode.

[0105] Figure 9 Figure 9 ​In the table, in the first row (#1), the state of the change in the amplitude of the received signal in the receiving signal transmission device 2C compared to normal when a communication signal is sent from the electronic device 1C to the signal transmission device 2C in the case where a short-circuit fault has occurred in either the inductor L1 or L2 in the filter circuit 13 of the electronic device 1C, which is the power supply side, is shown. On the other hand, in the second row (#2), the state of the change in the amplitude of the received signal in the receiving electronic device 1C compared to normal when a communication signal is sent from the signal transmission device 2C to the electronic device 1C, contrary to the first row, in the case where a short-circuit fault has occurred in either the inductor L1 or L2 in the filter circuit 13 of the electronic device 1C, which is the power supply side, is shown. Additionally, in the third row (#3), the state of the change in the amplitude of the received signal in the receiving signal transmission device 2C compared to normal when a communication signal is sent from the electronic device 1C to the signal transmission device 2C in the case where a short-circuit fault has occurred in either the inductor L3 or L4 in the filter circuit 23 of the signal transmission device 2C, which is the power distribution side, is shown. On the other hand, in the fourth row (#4), the state of the change in the amplitude of the received signal in the receiving electronic device 1C compared to normal when a communication signal is sent from the signal transmission device 2C to the electronic device 1C, contrary to the third row, in the case where a short-circuit fault has occurred in either the inductor L3 or L4 in the filter circuit 23 of the signal transmission device 2C, which is the power distribution side, is shown.

[0106] According to Figure 9 the second and third rows, it can be seen that regardless of whether the supply direction of the power supply current Id and the transmission direction of the communication signal are the same direction or the opposite direction, when a short-circuit fault occurs in the filter circuit 13 or 23 in the receiving side of the communication signal, as described in the first embodiment, the amplitude of the received communication signal becomes approximately half of the amplitude in the normal state. On the other hand, according to Figure 9 the first and fourth rows, it can be seen that regardless of whether the supply direction of the power supply current Id and the transmission direction of the communication signal are the same direction or the opposite direction, when a short-circuit fault occurs in the filter circuit 13 or 23 in the sending side of the communication signal, the amplitude of the received communication signal further decreases to less than approximately half of the amplitude in the normal state.

[0107] The decrease in the amplitude of the received signal caused by the short-circuit fault of the sending-side filter as described above occurs due to crosstalk between the two wires constituting the differential wiring 5. That is, when a short-circuit fault occurs in either of the inductors L1 to L4 in the filter circuits 13 and 23, in one of the pair of wires of the differential wiring 5 that is connected to the inductor, as Figure 3The potential shown in the table is fixed. However, for the wire whose potential is fixed due to crosstalk between wires that occurs when transmitting a communication signal via the differential wiring 5, the voltage fluctuation of the communication signal in the other wire is superimposed. As a result, as long as a slight potential fluctuation occurs in one wire, an amplitude reduction equivalent to the influence of crosstalk occurs in the received signal. The level of this amplitude reduction is, for example, between 5% and 20%, which is the general crosstalk coefficient of twisted pair wires.

[0108] Therefore, in the present embodiment, when it is known that a short-circuit fault has occurred in the filter circuits 13 and 23, two test modes with different signal transmission directions are executed, and the amplitudes of the respective received signals are measured. Then, a comparison is made between the results of the amplitude measurement, and the signal transmission direction of the side with the smaller amplitude of the received signal is determined. Thus, it is determined that a fault has occurred in the transmitter filter in this signal transmission direction. Thereby, it is possible to determine which one of the filter circuit 13 and the filter circuit 23 has a short-circuit fault.

[0109] Figure 10 FIG. is a flowchart showing the flow of the test mode of the sixth embodiment of the present invention. In step S201, the communication control unit 213 of the signal transmission device 2C of the signal transmission system 100C switches the signal transmission speed of the communication signal from the normal signal transmission speed T1 to the low-speed signal transmission speed T2. Thereby, a transition is made to the first transmission mode, which is a test low-speed signal transmission mode in which a communication signal is transmitted from the signal transmission device 2C on the power supply distribution side to the electronic device 1C on the power supply side.

[0110] Next, in step S202, the communication unit 11C on the side of the electronic device 1C having the power supply unit 12 that operates as a power supply circuit for supplying the power supply current Id to the signal transmission device 2C of the signal transmission system 100C receives the communication signal transmitted from the signal transmission device 2C at the signal transmission speed T2, and measures the amplitude of the received signal in the reception processing unit 112. Hereinafter, the amplitude of the received signal measured in step S202 will be referred to as "signal amplitude 1".

[0111] In step S203, the filter state determination unit 170 of the electronic device 1C of the signal transmission system 100C compares the signal amplitude 1 measured in step S202 with the amplitude of the received signal in the normal state set in advance, and determines whether the signal amplitude 1 is about 50% of the amplitude in the normal state. As a result, if it is determined that the signal amplitude 1 has been reduced to about 50% of the amplitude in the normal state, the process proceeds to step S204; otherwise, the process ends Figure 10 of the test mode shown in the flowchart.

[0112] In step S204, the signal transmission system 100C stores the signal with signal amplitude 1 measured in step S202 in a storage device (not shown) as signal amplitude information 1. Additionally, the storage device for storing the signal amplitude information 1 here can be built into the electronic device 1C or the signal transmission device 2C, or can be connected to the electronic device 1C or the signal transmission device 2C via a signal line (not shown).

[0113] Next, in step S205, the signal transmission system 100C uses the communication control unit 110 of the electronic device 1C to switch the signal transmission speed of the communication signal from the normal signal transmission speed T1 to a low signal transmission speed T2. Thereby, it transfers to the second transmission mode, which is a test low signal transmission mode for the electronic device 1C as the power supply provider to send a communication signal to the signal transmission device 2C as the power distribution provider.

[0114] In step S206, the signal transmission system 100C uses the communication unit 21C on the signal transmission device 2C side, which has a power supply unit 22 that operates as a power distribution circuit for the power supply current Id supplied by the electronic device 1C, to receive the communication signal sent from the electronic device 1C at the signal transmission speed T2, and measures the amplitude of the received signal in the reception processing unit 210. Hereinafter, the amplitude of the received signal measured in this step S205 is referred to as "signal amplitude 2".

[0115] In step S207, the signal transmission system 100C stores the information of signal amplitude 2 measured in step S206 in a storage device (not shown) as signal amplitude information 2. Additionally, the storage device for storing the signal amplitude information 2 here can be the same as or different from the storage device for storing the signal amplitude information 1 in step S204.

[0116] In step S208, the signal transmission system 100C reads the signal amplitude information 1 and the signal amplitude information 2 respectively stored in the storage device in steps S204 and S207, and based on this information, compares signal amplitude 1 with signal amplitude 2. As a result, if signal amplitude 1 is larger, it proceeds to step S209; if not, that is, if signal amplitude 2 is larger, it proceeds to step S210. Additionally, the processing after this step S208 can be implemented by either the filter state determination unit 170 of the electronic device 1C or the filter state determination unit 2 of the signal transmission device 2C, and can be implemented by either one.

[0117] In step S209, the signal transmission system 100C determines that the filter circuit 13 on the side of the electronic device 1C having the power supply unit 12 that operates as a power supply circuit for supplying the power supply current Id to the signal transmission device 2C is the occurrence location of a short circuit fault. Then, the information indicating the determined occurrence location of the short circuit fault is stored in the storage device, and the process proceeds to step S211.

[0118] In step S210, the signal transmission system 100C determines that the filter circuit 23 on the side of the signal transmission device 2C having the power supply unit 22 that operates as a power distribution circuit for distributing the power supply current Id supplied from the electronic device 1C is the occurrence location of a short circuit fault. Then, the information indicating the determined occurrence location of the short circuit fault is stored in the storage device, and the process proceeds to step S211.

[0119] In step S211, based on the information stored in the storage device in step S209 or S210, the signal transmission system 100C issues an alarm indicating that a short circuit fault has occurred in the PoDL filter and notifies the occurrence location of the fault. These notifications can be made to the user of the signal transmission system 100 or the superior system on which it is mounted by any method such as outputting a specified sound or image.

[0120] When the alarm and the notification of the fault location are made in step S211, or when it is determined in step S203 that the signal amplitude 1 has not decreased to about 50% of the normal level, the test mode shown in the flowchart Figure 10 ends.

[0121] According to the sixth embodiment of the present invention described above, the electronic device 1C and the signal transmission device 2C can communicate with each other bidirectionally. In the first transmission mode in which the communication signal is transmitted from the signal transmission device 2C to the electronic device 1C (step S201), the communication unit 11C receives the communication signal transmitted from the communication unit 21C at the signal transmission speed T2 via the differential wiring 5, and the reception processing unit 112 measures the amplitude of the received communication signal (step S202). Further, in the second transmission mode in which the communication signal is transmitted from the electronic device 1C to the signal transmission device 2C (step S205), the communication unit 21C receives the communication signal transmitted from the communication unit 11C at the signal transmission speed T2 via the differential wiring 5, and the reception processing unit 210 measures the amplitude of the received communication signal (step S206). Then, the signal processing unit 17 of the electronic device 1C or the signal processing unit 27 of the signal transmission device 2C compares the amplitudes respectively measured by the communication unit 11C and the communication unit 21C using the filter state determination units 170 and 270 (step S208), and based on the comparison result, determines which one of the filter circuits 13 and 23 has a short circuit failure (steps S209 and S210). Because of this, it is possible to reliably determine which one of the filter circuits 13 and 23 has a short circuit failure.

[0122] (Seventh Embodiment)

[0123] Next, a seventh embodiment of the present invention will be described. In this embodiment, an example of a process of implementing a test mode for detecting a short circuit failure of the PoDL filter in various inspections performed when starting the vehicle in which the signal transmission system 100 is mounted will be described. Further, in this embodiment, an example of a case where the test mode is implemented in the signal transmission system 100 described in the first embodiment will be described, but when the test mode is implemented in the signal transmission system 100A described in the second embodiment, or the signal transmission system 100B described in the fourth embodiment, or the signal transmission system 100C described in the fifth embodiment, the test mode can also be implemented using the same process.

[0124] Figure 11It is a flowchart showing the process of the test mode of the seventh embodiment of the present invention. In an automobile equipped with the signal transmission system 100, when the automobile starts due to engine ignition or the like, various electrical and electronic devices in the automobile are powered for initialization. At this time, when implementing the initialization program for the electronic devices of the communication system including the signal transmission system 100 in step S301, after the signal transmission system 100 performs various tests in step S302, it transfers to the test mode of the PoDL filter in step S303. Thus, various tests are included in the initialization program of the signal transmission system 100 implemented when the automobile starts, and the test mode for detecting a short-circuit fault of the PoDL filter is also carried out as one of the various tests.

[0125] In step S303, the signal transmission system 100 uses the communication control unit 110 of the electronic device 1 to switch the signal transmission speed of the communication signal from the normal signal transmission speed T1 to the low signal transmission speed T2, thereby transferring to the low-speed signal transmission mode for testing.

[0126] Next, in step S304, the signal transmission system 100 uses the communication unit 21 of the signal transmission device 2 to receive the communication signal sent from the electronic device 1 at the signal transmission speed T2, and measures the amplitude of the received signal in the reception processing unit 210.

[0127] In step S305, the signal transmission system 100 uses the filter state determination unit 270 of the signal transmission device 2 to compare the amplitude of the received signal measured in step S304 with the amplitude of the received signal in the normal state set in advance, and determines whether the amplitude of the measured received signal is about 50% of the normal state. As a result, when it is determined that the amplitude of the measured received signal has decreased to about 50% of the normal state, in step S306, an alarm notification indicating that a short-circuit fault has occurred in one of the PoDL filters, that is, the filter circuits 13 and 23, is performed. In addition, the alarm notification of the short-circuit fault can be carried out for users such as the driver of the automobile by any method such as outputting a specified sound or image.

[0128] When the alarm notification is performed in step S306, or when it is determined in step S305 that the amplitude of the measured received signal has not decreased to about 50% of the normal state, the Figure 11 test mode shown in the flowchart ends.

[0129] In addition, in the above description, according to the process of the test mode described in the third embodiment, an example of the process of the test mode performed when the automobile starts is described. However, it is also possible to determine in which device the short-circuit fault occurs when detecting the short-circuit fault of the PoDL filter by implementing the process of the test mode described in the sixth embodiment when the automobile starts. In this case, instead of Figure 11Implement in steps S303 to S307 Figure 10 Just perform the processes of steps S201 to S211

[0130] According to the seventh embodiment of the present invention described above, the signal transmission system 100 is mounted in an automobile. In the electronic device 1, when the automobile is started, the communication unit 11 transmits a communication signal at the signal transmission speed T2. In the signal transmission device 2, when receiving the communication signal transmitted at the signal transmission speed T2 from the communication unit 11, the communication unit 21 receives the communication signal with the differential reception circuit 211 and the reception processing unit 210 and measures the amplitude. The signal processing unit 27 uses the filter state determination unit 270 to detect a short circuit fault of the filter circuit 13 or the filter circuit 23 based on the amplitude measured by the communication unit 21. Because of this, in the signal transmission system 100 mounted in the automobile, it is possible to detect a short circuit fault of the filter circuits 13 and 23 at an appropriate timing.

[0131] (Eighth Embodiment)

[0132] Next, the eighth embodiment of the present invention will be described. In this embodiment, an example of the process of implementing a test mode for detecting a short circuit fault of the PoDL filter that occurs during the operation of an automobile in which the signal transmission system 100 is mounted will be described. In addition, in this embodiment as well as in the above-described seventh embodiment, an example of the case where the test mode is implemented in the signal transmission system 100 described in the first embodiment will be described. However, when the test mode is implemented in the signal transmission system 100A described in the second embodiment, or the signal transmission system 100B described in the fourth embodiment, or the signal transmission system 100C described in the fifth embodiment, the test mode can also be implemented using the same process.

[0133] Figure 12 It is a flowchart showing the process of the test mode of the eighth embodiment of the present invention. In step S401, when it is determined that a certain time has elapsed since the start of operation of the automobile in which the signal transmission system 100 is mounted, the signal transmission system 100 determines in step S402 whether a parameter regarding the signal quality has changed significantly. Here, the parameter regarding the signal quality is, for example, the number of errors of the CRC (Cyclic Redundancy Check) and a significant change in the equalizer setting value. As a result, when it is determined that the parameter regarding the signal quality has changed significantly, after performing various tests in step S403, the process proceeds to the test mode of the PoDL filter in step S404. In this way, when the quality of the communication signal changes during the operation of the automobile, various tests of the communication system are performed, and the test mode for detecting a short circuit fault of the PoDL filter is also performed as one of the various tests.

[0134] In step S404, the signal transmission system 100 uses the communication control unit 110 of the electronic device 1 to switch the signal transmission speed of the communication signal from the normal signal transmission speed T1 to the low-speed signal transmission speed T2, thereby transferring to the low-speed signal transmission mode for testing.

[0135] Next, in step S405, the signal transmission system 100 uses the communication unit 21 of the signal transmission device 2 to receive the communication signal transmitted from the electronic device 1 at the signal transmission speed T2, and measures the amplitude of the received signal in the reception processing unit 210.

[0136] In step S406, the signal transmission system 100 uses the filter state determination unit 270 of the signal transmission device 2 to compare the amplitude of the received signal measured in step S405 with the amplitude of the received signal in the normal state set in advance, and determines whether the amplitude of the measured received signal is about 50% of the normal state. As a result, when it is determined that the amplitude of the measured received signal has decreased to about 50% of the normal state, in step S407, an alarm notification indicating that a short circuit fault has occurred in one of the PoDL filters, that is, the filter circuits 13 and 23, is performed. In addition, the alarm notification of the short circuit fault can be performed on a user such as a driver of the vehicle by any method such as outputting a specified sound or image.

[0137] When the alarm notification is performed in step S407, or when it is determined in step S406 that the amplitude of the measured received signal has not decreased to about 50% of the normal state, the test mode for detecting the short circuit fault of the PoDL filter is ended in step S408. After that, if the operation of the vehicle continues, the process returns to step S402 to continue the test mode.

[0138] In addition, in the above description, the flow example of the test mode performed when the vehicle is started is described according to the flow of the test mode described in the third embodiment. However, it is also possible to determine in which device the short circuit fault has occurred when the short circuit fault of the PoDL filter is detected by implementing the flow of the test mode described in the sixth embodiment when the vehicle is started. In this case, instead of Figure 12 steps S404 to S408, the processes of Figure 10 steps S201 to S211 are implemented.

[0139] According to the eighth embodiment of the present invention described above, the signal transmission system 100 is mounted in an automobile. In the electronic device 1, when a communication signal abnormality occurs during vehicle travel, the communication unit 11 switches from the signal transmission speed T1 to the signal transmission speed T2 and transmits the communication signal. In the signal transmission device 2, when receiving the communication signal at the signal transmission speed T2 from the communication unit 11, the communication unit 21 receives the communication signal with the differential reception circuit 211 and the reception processing unit 210 and measures the amplitude. The signal processing unit 27 uses the filter state determination unit 270 to detect a short circuit failure of the filter circuit 13 or the filter circuit 23 based on the amplitude measured by the communication unit 21. Because of this, in the signal transmission system 100 mounted in an automobile, it is possible to detect a short circuit failure of the filter circuits 13 and 23 at an appropriate timing when a communication signal abnormality occurs.

[0140] (Ninth Embodiment)

[0141] Next, the ninth embodiment of the present invention will be described. In this embodiment, the connection structure of the power supply unit for reducing the influence on the communication signal quality when a short circuit failure of the PoDL filter occurs will be described.

[0142] Figure 13 FIG. is a diagram showing the connection structure of the power supply unit 12 according to the ninth embodiment of the present invention. In this embodiment, in the signal transmission system 100 described in the first embodiment, the wiring between the inductors L1 and L2 of the filter circuit 13 in the power supply circuit, that is, the power supply unit 12, provided in the electronic device 1 is adjusted to a length of 1 / 4 of the wavelength λ of the communication signal as Figure 13 shown. Thus, when a short circuit failure of the inductors L1 and L2 occurs in the filter circuit 13, the wiring portion connected to the inductor can function as an open stub filter. Since this open stub filter functions as a band-stop filter, it has the effect of filtering out external interference superimposed on the wiring where the short circuit failure occurs in the signal wirings 15P and 15N and improving the quality of the communication signal. At this time, by making the impedance of the power supply unit 12 at the signal transmission speed during communication sufficiently high in the high frequency band, the effect of the open stub filter as described above can be further improved.

[0143] (Tenth Embodiment)

[0144] Next, the signal transmission system according to the tenth embodiment of the present invention will be described. In this embodiment, a communication method when a PoDL filter of a certain electronic device fails in a signal transmission system in which multiple electronic devices can communicate with each other will be described.

[0145] Figure 14It is a diagram showing the configuration of a signal transmission system 100D according to a tenth embodiment of the present invention. Figure 14 The signal transmission system 100D shown is installed in an automobile. Electronic control units (ECUs) 1-1 through 1-5 are connected via differential wiring 5-1 through 5-5, forming a ring-shaped network. ECUs 1-1 through 1-5 have the same structure as the electronic devices 1 through 1C or signal transmission units 2 through 2C described in the above embodiments, respectively. They can communicate and supply power to each other via differential wiring 5-1 through 5-5. Furthermore, each ECU incorporates a built-in PoDL filter, enabling detection of a short-circuit failure in the PoDL filter.

[0146] In a network such as signal transmission system 100D, if a PoDL filter short-circuit failure occurs in an ECU, communication may continue despite signal degradation during transmission through the communication path including the filter. However, because communication signals are transmitted single-ended in a signal system that is intended for differential transmission, EMC (Electromagnetic Compatibility) issues may arise. Specifically, the common-mode current increases due to the short-circuit failure of the PoDL filter, and the resulting electromagnetic noise is generated within the vehicle's onboard systems, including signal transmission system 100D, potentially causing malfunctions in other equipment installed in the vehicle. Therefore, if a PoDL filter short-circuit failure is detected in signal transmission system 100D, it is preferable to switch to a control mode that suppresses the frequency of communication through the communication path and prevents an increase in the energy density of the electromagnetic noise generated by signal transmission system 100D.

[0147] In the signal transmission system 100D of this embodiment, as described above, when a short-circuit failure of a PoDL filter is detected in any of the ECUs 1-1 to 1-5, control is performed to suppress the communication frequency of the communication path through the filter. Figure 14 As shown, assume that ECU 1-1 detects a short-circuit fault in the PoDL filter connected to differential wiring 5-1 between ECU 1-1 and ECU 1-2. In this case, power is maintained between ECU 1-1 and ECU 1-2 via differential wiring 5-1, while the communication frequency of the communication path including differential wiring 5-1 is reduced, giving priority to communication via the communication path that bypasses differential wiring 5-1 and passes through differential wirings 5-2 to 5-5. This approach, while disadvantageous in terms of communication delay, reduces the risk of malfunction caused by noise in the entire vehicle system, allowing the vehicle system to continue operating. Furthermore, the above control can be performed by either ECU 1-1 or ECU 1-2, or by the other ECU.

[0148] According to the tenth embodiment of the present invention described above, in the signal transmission system 100D, the ECU 1-1 and the ECU 1-2 can communicate with each other via a communication path including the differential wiring 5-1 and a communication path not including the differential wiring 5-1. When the communication units respectively provided in the ECU 1-1 and the ECU 1-2 detect a short-circuit failure of the PoDL filter, they give priority to using the communication path not including the differential wiring 5-1 over the communication path including the differential wiring 5-1 for transmitting and receiving communication signals. Because of this, it is possible to suppress the generation of electromagnetic noise in the case of a failure of the PoDL filter and prevent malfunction of other devices.

[0149] (Eleventh Embodiment)

[0150] Next, a signal transmission system according to the eleventh embodiment of the present invention will be described. In this embodiment, a method for warning a driver of an automobile when a short-circuit failure occurs in a PoDL filter in the signal transmission system mounted in the automobile will be described.

[0151] Figure 15 FIG. is a diagram showing the configuration of a vehicle-mounted system including a signal transmission system according to the eleventh embodiment of the present invention. Figure 15 The vehicle-mounted system shown is mounted in an automobile 40 and configured to include the signal transmission system 100 described in the first embodiment. In the signal transmission system 100, the signal transmission device 2 is connected to an in-vehicle network 41 such as a CAN (Controller Area Network).

[0152] In the signal transmission system 100, when a short-circuit failure is detected in either the PoDL filter, i.e., the filter circuit 13 or 23, of the electronic device 1 or the signal transmission device 2, the signal transmission device 2 sends a failure message to the gateway 42 connected via the in-vehicle network 41. This failure message is transmitted from the gateway 42 to the user interface unit 43 provided in the automobile 40. The user interface unit 43 is an information processing device that gives a prescribed warning to the driver 47 riding in the automobile 40 using an image, an alarm sound, a voice, etc., based on the failure message sent from the signal transmission device 2 via the gateway 42. Thereby, it is possible to notify the driver 47 that a short-circuit failure has occurred in the PoDL filter in the signal transmission system 100 and prompt the driver 47 to make a judgment such as switching to a safe driving mode.

[0153] In addition, in the present embodiment, an example of a vehicle-mounted system including the signal transmission system 100 described in the first embodiment has been described. However, in a vehicle-mounted system including the signal transmission system 100A described in the second embodiment, or the signal transmission system 100B described in the fourth embodiment, or the signal transmission system 100C described in the fifth embodiment, or the signal transmission system 100D described in the tenth embodiment, the same processing as in the present embodiment can also be implemented. In addition, the failure information may be output from the signal transmission device 2 to the user interface unit 43 via the in-vehicle network 41 without using the gateway 42. In either case, when a short-circuit failure of the PoDL filter occurs in the signal transmission system, the failure information for warning the driver 47 can be output from the device in the signal transmission system to the user interface unit 43.

[0154] According to the eleventh embodiment of the present invention described above, the signal transmission system 100 is mounted in an automobile 40 having an in-vehicle network 41 and a user interface unit 43 that controls warnings to the driver 47 and is connected to the in-vehicle network 41 via a gateway 42. When the signal transmission device 2 detects a short-circuit failure of the PoDL filter, it sends failure information for giving a prescribed warning to the driver 47 to the user interface unit 43 via the in-vehicle network 41. For this reason, when a failure occurs in the PoDL filter in the signal transmission system 100, the driver 47 can be immediately notified of the situation.

[0155] (Twelfth Embodiment)

[0156] Next, the signal transmission system according to the twelfth embodiment of the present invention will be described. In the present embodiment, a notification method in the case where a short-circuit failure of the PoDL filter occurs during vehicle inspection in a signal transmission system mounted in an automobile will be described.

[0157] Figure 16 FIG. is a diagram showing the configuration of a vehicle-mounted system including a signal transmission system according to the twelfth embodiment of the present invention. Figure 16 The vehicle-mounted system shown is mounted in an automobile 40 and is configured to include the signal transmission system 100 described in the first embodiment. In the signal transmission system 100, the signal transmission device 2 is connected to an in-vehicle network 41 such as CAN in the same manner as described in the eleventh embodiment.

[0158] When inspecting the vehicle 40, the communication port 44 for inspection signals provided in the vehicle 40 is connected to the fault diagnosis device 46 via the relay device 45. In the signal transmission system 100, when a short-circuit fault is detected in either the PoDL filter, i.e., the filter circuits 13, 23, of the electronic device 1 or the signal transmission device 2, the signal transmission device 2 sends a fault message to the gateway 42 connected via the in-vehicle network 41. This fault message is transmitted from the gateway 42 to the fault diagnosis device 46 via the communication port 44 and the relay device 45 in a prescribed signal format such as OBD2. Based on the fault message sent from the signal transmission device 2 via the gateway 42, the fault diagnosis device 46 performs a screen display indicating that a short-circuit fault has occurred in the filter circuits 13, 23. Thus, an inspector holding the fault diagnosis device 46 can easily learn that a short-circuit fault has occurred in the PoDL filter within the signal transmission system 100. As a result, the operation process and replacement parts during fault repair can be minimized, so the cost can be reduced.

[0159] In addition, in the present embodiment, an example of an in-vehicle system including the signal transmission system 100 described in the first embodiment has been described. However, in an in-vehicle system including the signal transmission system 100A described in the second embodiment, or the signal transmission system 100B described in the fourth embodiment, or the signal transmission system 100C described in the fifth embodiment, or the signal transmission system 100D described in the tenth embodiment, the same processing as in the present embodiment can also be implemented. In addition, the fault message can be output from the signal transmission device 2 via the in-vehicle network 41 to the fault diagnosis device 46 connected to the communication port 44 without using the gateway 42 or the relay device 45. In either case, when a short-circuit fault of the PoDL filter occurs in the signal transmission system, a fault message regarding the short-circuit fault can be sent from a device within the signal transmission system to the fault diagnosis device 46 connected to the communication port 44.

[0160] According to the twelfth embodiment of the present invention described above, the signal transmission system 100 is mounted in a vehicle 40 having an in-vehicle network 41 and a communication port 44 for connecting the in-vehicle network 41 to an external fault diagnosis device 46. When the signal transmission device 2 detects a short-circuit fault of the PoDL filter, it sends a fault message regarding the short-circuit fault to the fault diagnosis device 46 connected to the communication port 44 via the in-vehicle network 41. Because of this, when a fault occurs in the PoDL filter in the signal transmission system 100, this situation can be notified to the inspector during the inspection of the vehicle 40.

[0161] (Thirteenth Embodiment)

[0162] Next, a signal transmission system according to a thirteenth embodiment of the present invention will be described. In this embodiment, a method for providing repair recommendation information to a user of an automobile when a short-circuit failure occurs in a PoDL filter in a signal transmission system mounted in an automobile used as a connected vehicle will be described.

[0163] Figure 17 FIG. is a diagram showing the configuration of an information providing system according to a thirteenth embodiment of the present invention. Figure 17 The information providing system shown is mounted in an automobile 40 and configured to include an in-vehicle system including a signal transmission system 100 described in the first embodiment, and a server device 31 that provides an abnormality diagnosis / analysis service. In the signal transmission system 100, the signal transmission device 2 is connected to an in-vehicle network 41 such as a CAN in the same manner as described in the eleventh embodiment.

[0164] In the signal transmission system 100, when a short-circuit failure is detected in a PoDL filter, i.e., one of the filter circuits 13 and 23, of the electronic device 1 or the signal transmission device 2, the signal transmission device 2 sends a failure message to a gateway 42 connected via the in-vehicle network 41. This failure message is transferred from the gateway 42 to a communication unit 49 provided in the automobile 40. The communication unit 49 is a communication device that performs wireless communication and sends the failure message together with the user information and vehicle information of the automobile 40 to the server device 31 connected via the cloud 30.

[0165] The server device 31 is provided at a location different from the automobile 40 and, based on the failure message and vehicle information sent from the signal transmission device 2 via the gateway 42, the communication unit 49, and the cloud 30, makes an inquiry to a vehicle manufacturing information database 32 regarding the failure target components, i.e., the filter circuits 13 and 23. The vehicle manufacturing information database 32 has a database of various components registered in advance for each vehicle model, retrieves information on the failure target components in response to the inquiry made by the server device 31, and sends the retrieval result to the server device 31. Thus, the server device 31 can obtain failure target component information on the filter circuits 13 and 23 in which a short-circuit failure has occurred in the signal transmission system 100 mounted in the automobile 40.

[0166] After obtaining the failure target component information from the vehicle manufacturing information database 32, the server device 31 makes an inquiry to a repairer 33 who repairs the automobile 40 as to whether the failure target components can be repaired. In addition, Figure 17As the maintenance providers 33, there are two providers A and B. An example of asking them whether they can perform repairs is illustrated, but the number of maintenance providers 33 making the inquiries is not limited to this. Each maintenance provider 33 that receives an inquiry from the server device 31 responds to the inquiry by sending information such as whether it can perform repairs, the period when it can perform repairs, and the repair amount to the server device 31.

[0167] After obtaining responses from each maintenance provider 33, the server device 31 generates recommended repair information regarding the short - circuit fault that occurred in the filter circuits 13 and 23 based on the obtained responses, and sends it to the information terminal 48 such as a smartphone held by the user of the vehicle 40 via the cloud 30. This recommended repair information includes information about the maintenance providers 33 that can perform repairs, the period when repairs can be made, the repair amount, and other information. The information terminal 48 displays the received recommended repair information on the screen and provides it to the user. Thus, when a short - circuit fault occurs in the PoDL filter within the signal transmission system 100 of the vehicle 40, the user of the vehicle 40 can easily obtain useful information regarding subsequent repairs. Furthermore, by receiving inquiries about whether repairs can be made from the server device 31 in advance, each maintenance provider 33 can plan its response to the fault.

[0168] In addition, in this embodiment, an example of a vehicle system including the signal transmission system 100 described in the first embodiment is illustrated. However, the same processing as in this embodiment can also be implemented in a vehicle system including the signal transmission system 100A described in the second embodiment, or the signal transmission system 100B described in the fourth embodiment, or the signal transmission system 100C described in the fifth embodiment, or the signal transmission system 100D described in the tenth embodiment. Additionally, Figure 17 An example of providing recommended repair information to the user by sending the recommended repair information from the server device 31 to the information terminal 48 is illustrated. However, the recommended repair information can also be provided to the user by sending the recommended repair information from the server device 31 to the communication unit 49 and displaying the recommended repair information on the user interface unit 43 connected via the gateway 42. In either case, when a short - circuit fault occurs in the PoDL filter in the signal transmission system, the server device 31 can be used to provide the user of the vehicle 40 with information regarding the repair of this short - circuit fault.

[0169] According to the thirteenth embodiment of the present invention described above, the signal transmission system 100 is mounted in an automobile having an in-vehicle network 41 and a communication unit 49, which is a communication device that performs wireless communication and is connected to the in-vehicle network 41 via a gateway 42. When the signal processing unit 27 in the signal transmission device 2 detects a short-circuit fault of the PoDL filter, fault information about the short-circuit fault is sent from the signal transmission device 2 to the communication unit 49 via the in-vehicle network 41. Then, the fault information is sent to a server device 31 provided at a location different from that of the automobile 40 through the wireless communication performed by the communication unit 49. The server device 31 uses a pre-registered vehicle manufacturing information database 32 to obtain fault target component information about the filter circuit 13 or the filter circuit 23 corresponding to the PoDL filter in which the short-circuit fault has occurred. After that, based on the obtained fault target component information, the server device 31 inquires a repairer 33 who repairs the automobile 40 about whether repair is possible, and sends recommended repair information based on the result of the inquiry from the server device 31. In this way, based on the recommended repair information sent by the server device 31, information about the repair of the short-circuit fault is provided to the user of the automobile 40. Because of this, when a fault occurs in the PoDL filter in the signal transmission system 100, useful information about subsequent maintenance can be provided to the user, and the usability of the automobile 40 equipped with the signal transmission system 100 is improved.

[0170] (The fourteenth embodiment)

[0171] Next, a signal transmission system according to the fourteenth embodiment of the present invention will be described. In the present embodiment, a method for providing statistical information about faults to the manufacturer and seller of an automobile based on the occurrence history of a short-circuit fault of a PoDL filter in a signal transmission system mounted in an automobile used as a connected vehicle will be described.

[0172] Figure 18 FIG. is a diagram showing the structure of an information providing system according to the fourteenth embodiment of the present invention. Figure 18 The information providing system shown is configured to include a plurality of automobiles 40 and a server device 31 that provides an abnormality diagnosis / analysis service. In each automobile 40, similar to the Figure 13 information providing system described in the Figure 17 embodiment, an in-vehicle system is mounted that includes the signal transmission system 100 described in the first embodiment.

[0173] In the information providing system according to the present embodiment, the same processing as that described in the thirteenth embodiment is performed between the in-vehicle system of each vehicle 40 and the server device 31. That is, when a short-circuit fault of the PoDL filter occurs in the signal transmission system within the in-vehicle system, fault information regarding the short-circuit fault is transmitted from each vehicle 40 to the server device 31 via the cloud 30, and the server device 31 inquires of the repairer 33 whether repair is possible. Then, based on the response from the repairer 33, recommended repair information regarding the repair of the short-circuit fault is generated in the server device 31 and provided to the users of each vehicle 40 from the server device 31 via the cloud 30.

[0174] Furthermore, in the information providing system according to the present embodiment, the server device 31 generates statistical information regarding faults of the PoDL filter in the signal transmission system by collecting the fault information transmitted from each vehicle 40 and performing statistical processing. This statistical information includes differences in the fault frequencies of other component groups having the same function, the occurrence frequency of faults, variance information of the usage time until faults, and the like. By applying the statistical information generated in this way, the server device 31 provides useful values to the vehicle manufacturer 34 that manufactures the vehicle 40 and the retailer 35 that sells the vehicle 40, respectively. For example, the vehicle manufacturer 34 can obtain information regarding components of the same performance with lower fault frequencies based on the statistical information provided by the server device 31, and consider replacing them with components having higher reliability based on this information. In addition, the retailer 35 can obtain information on the quantity and fault frequency of the target components sold on the market based on the statistical information provided by the server device 31, and perform component inventory management based on this information to optimize the component inventory.

[0175] According to the fourteenth embodiment of the present invention described above, statistical information regarding faults of the filter circuit 13 and the filter circuit 23 is generated by performing statistical processing on the fault information received from each of the plurality of vehicles 40 using the server device 31. Then, the statistical information generated by the server device 31 is provided to the vehicle manufacturer 34 or the retailer 35. Because of this, useful values can be provided to the vehicle manufacturer 34 that manufactures the vehicle 40 and the retailer 35 that sells the vehicle 40, respectively.

[0176] Each of the embodiments and various modifications described above is merely an example, and the present invention is not limited to these contents as long as the features of the invention are not impaired. In addition, although various embodiments and modifications have been described above, the present invention is not limited to these contents. Other modes conceivable within the technical idea of the present invention are also included within the scope of the present invention.

[0177] Explanation of Reference Numerals

[0178] 1, 1A, 1C, 1Z... electronic devices, 2, 2A, 2B, 2C, 2Z... signal transmission devices, 5... differential wiring, 11, 11C, 11Z... communication units, 12, 12A... power supply units, 13... filter circuit, 14N, 14P... capacitors, 15N, 15P... signal wiring, 16... connector, 17... signal processing unit, 21, 21C, 21Z... communication units, 22, 22A... power supply units, 23... filter circuit, 24N, 24P... capacitors, 25N, 25P... signal wiring, 26... connector, 27, 27Z... signal processing units, 28... storage device, 100, 100A, 100B, 100C, 100D, 100Z... signal transmission systems, 110, 110Z... communication control units, 111... differential transmission circuit, 112... receiving processing unit, 113... differential receiving circuit, 114... waveform equalization circuit, 170... filter state judgment unit, 210, 210Z... receiving processing units, 211... differential receiving circuit, 212... waveform equalization circuit, 213... communication control unit, 214... differential transmission circuit, 270... filter state judgment unit.

Claims

1. A signal transmission device connected to an electronic device by differential wiring composed of a pair of electric wires, characterized in that, Comprising: a communication unit capable of performing differential transmission-based communication between the differential wiring and the electronic device; and a signal processing unit that performs signal processing on the communication, wherein the electronic device and the signal transmission device each have a power supply unit capable of supplying a power current via the differential wiring, and a filter circuit electrically connected between the differential wiring and the power supply unit, the communication unit is capable of receiving communication signals transmitted from the electronic device via the differential wiring at a plurality of signal transmission speeds including at least a first signal transmission speed and a second signal transmission speed lower than the first signal transmission speed, the communication unit measures the amplitude of the communication signal received from the electronic device at the second signal transmission speed, the signal processing unit detects a short-circuit fault of the filter circuit based on the amplitude measured by the communication unit.

2. The signal transmission device according to claim 1, wherein: the power supply unit of the electronic device applies a prescribed potential difference between the pair of wires to supply the power current to the signal transmission device, the power supply unit of the signal transmission device distributes the power current supplied from the electronic device to the communication unit and the signal processing unit.

3. The signal transmission device according to claim 1, wherein: the power supply unit of the signal transmission device applies a prescribed potential difference between the pair of wires to supply the power current to the electronic device.

4. The signal transmission device according to any one of claims 1 to 3, wherein: the communication unit has an equalizer function of adjusting the waveform of the communication signal within a prescribed effective frequency range to compensate for attenuation caused by the differential wiring, the second signal transmission speed is a signal transmission speed at which the frequency of the communication signal is lower than the effective frequency range.

5. The signal transmission device according to any one of claims 1 to 3, wherein: the second signal transmission speed is a signal transmission speed at which the frequency of the communication signal is 1 / 20 or less of the fundamental frequency of the communication signal transmitted at the first signal transmission speed.

6. The signal transmission device according to any one of claims 1 to 3, wherein: it has a storage device that stores amplitude information regarding the amplitude of the communication signal when no short-circuit fault occurs in the filter circuit, the signal processing unit detects a short-circuit fault of the filter circuit based on the amplitude measured by the communication unit and the amplitude information stored in the storage device.

7. A signal transmission system, wherein: it includes a first electronic device and a second electronic device connected to the first electronic device by a differential wiring composed of a pair of wires, the first electronic device includes: a pair of first signal wirings respectively connected to the differential wiring; a first communication unit capable of performing differential transmission-based communication between the second electronic device via the first signal wiring and the differential wiring; a first power supply unit capable of supplying a power current via the differential wiring; and A first filter circuit having a pair of filter elements respectively connected between the pair of first signal wirings and the first power supply unit. The second electronic device includes: A pair of second signal wirings respectively connected to the differential wiring; A second communication unit that communicates with the first electronic device via the second signal wiring and the differential wiring; A second signal processing unit capable of performing signal processing on the communication; A second power supply unit capable of supplying the power current via the differential wiring; and A second filter circuit having a pair of filter elements respectively connected between the pair of second signal wirings and the second power supply unit. The first communication unit transmits communication signals at various signal transmission speeds including at least a first signal transmission speed and a second signal transmission speed lower than the first signal transmission speed. The second communication unit receives the communication signal transmitted from the first communication unit via the differential wiring and measures the amplitude of the communication signal received at the second signal transmission speed. The second signal processing unit detects a short-circuit fault of the first filter circuit or the second filter circuit based on the amplitude measured by the second communication unit.

8. The signal transmission system according to claim 7, wherein: The first power supply unit supplies the power current to the second electronic device by applying a prescribed potential difference between the pair of first signal wirings. The second power supply unit distributes the power current supplied from the first power supply unit to the second communication unit and the second signal processing unit.

9. The signal transmission system according to claim 7, wherein: The second power supply unit supplies the power current to the first electronic device by applying a prescribed potential difference between the pair of second signal wirings. The first power supply unit distributes the power current supplied from the second power supply unit to the first communication unit.

10. The signal transmission system according to any one of claims 7 to 9, wherein: The first electronic device has a first signal processing unit that performs signal processing on the communication. The first communication unit and the second communication unit can communicate with each other bidirectionally. In a first transmission mode in which the communication signal is transmitted from the second electronic device to the first electronic device, the first communication unit receives the communication signal transmitted from the second communication unit at the second signal transmission speed via the differential wiring and measures the amplitude. In a second transmission mode in which the communication signal is transmitted from the first electronic device to the second electronic device, the second communication unit receives the communication signal transmitted from the first communication unit at the second signal transmission speed via the differential wiring and measures the amplitude. The first signal processing unit or the second signal processing unit compares the amplitudes measured by the first communication unit and the second communication unit respectively, and determines which one of the first filter circuit and the second filter circuit has a short-circuit fault based on the result of the comparison.

11. The signal transmission system according to any one of claims 7 to 9, characterized in that: The signal transmission system is mounted on an automobile, When the automobile is started, the first communication unit transmits the communication signal at the second signal transmission speed, When receiving the communication signal transmitted from the first communication unit at the second signal transmission speed, the second communication unit receives the communication signal and measures the amplitude, The second signal processing unit detects the short-circuit fault based on the amplitude measured by the second communication unit.

12. The signal transmission system according to any one of claims 7 to 9, characterized in that: The signal transmission system is mounted on an automobile, When an abnormality occurs in the communication signal during the running of the automobile, the first communication unit switches from the first signal transmission speed to the second signal transmission speed to transmit the communication signal, When receiving the communication signal transmitted from the first communication unit at the second signal transmission speed, the second communication unit receives the communication signal and measures the amplitude, The second signal processing unit detects the short-circuit fault based on the amplitude measured by the second communication unit.

13. The signal transmission system according to any one of claims 7 to 9, characterized in that: The first electronic device and the second electronic device can communicate with each other via a first communication path including the differential wiring and a second communication path not including the differential wiring, When the second signal processing unit detects the short-circuit fault, the first communication unit and the second communication unit preferentially use the second communication path to transmit and receive the communication signal compared to the first communication path.

14. The signal transmission system according to any one of claims 7 to 9, characterized in that: The signal transmission system is mounted on an automobile having an in-vehicle network and an information processing device connected to the in-vehicle network for controlling warnings to the driver, When detecting the short-circuit fault, the second electronic device sends fault information for giving a prescribed warning to the driver to the information processing device via the in-vehicle network.

15. The signal transmission system according to any one of claims 7 to 9, characterized in that: The signal transmission system is mounted on an automobile having an in-vehicle network and a communication port for connecting the in-vehicle network to an external fault diagnosis device, When detecting the short-circuit fault, the second electronic device sends fault information about the short-circuit fault to the fault diagnosis device connected to the communication port via the in-vehicle network. I6. An information providing method using a signal transmission system, characterized in that: The signal transmission system is the signal transmission system according to any one of claims 7 to 9, The signal transmission system is mounted on an automobile having an in-vehicle network and a communication device connected to the in-vehicle network for performing wireless communication, When the second signal processing unit detects the short-circuit fault, fault information about the short-circuit fault is sent from the second electronic device to the communication device via the in-vehicle network, Wireless communication performed by the communication device transmits the fault information to a server device disposed at a location different from the vehicle. The server device uses a pre-registered database to obtain fault object component information regarding the first filter circuit or the second filter circuit in which the short-circuit fault has occurred. The server device inquires of a repairer who repairs the vehicle as to whether repair is possible based on the fault object component information. Recommendation repair information based on the result of the inquiry is transmitted from the server device. Information regarding repair of the short-circuit fault is provided to a user of the vehicle based on the recommendation repair information transmitted by the server device.

17. The information providing method according to claim 16, wherein: The server device performs statistical processing on the fault information received from the plurality of vehicles respectively to generate statistical information regarding faults of the first filter circuit and the second filter circuit. The server device provides the generated statistical information to a manufacturer or a seller of the vehicle.

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