JP6402929B2 - Cable signal detector - Google Patents

Description

  The present invention relates to a cable signal detector.

  In a data center or the like, a connection change of a communication cable such as a LAN (Local Area Network) cable is performed in accordance with a layout change, movement, or addition of an information communication device such as a server or a hub.

  In order to determine whether or not a communication cable is connected, some information communication devices have a connection confirmation lamp for confirming the connection of the communication cable.

  In addition, there has been proposed one that detects insertion or removal of a connector of a communication cable and monitors connection of the communication cable (see, for example, Patent Document 1).

Japanese Patent No. 5274671

  However, in the above-described prior art, it is only possible to confirm whether or not the communication cable is physically connected, and whether or not communication is actually performed using the communication cable, that is, information communication There is a problem that the presence or absence cannot be confirmed.

  Therefore, there is a possibility that the communication cable may be accidentally disconnected without noticing that the communication is in progress, and problems such as suspension of the service of the information communication device or corruption of data being transferred may occur.

  Further, when monitoring the connection of a communication cable as in Patent Document 1, it is necessary to incorporate a monitoring signal line in the communication cable, so that a general-purpose communication cable cannot be used, and the cost increases. There is also.

  Furthermore, it may be possible to display the presence / absence of information communication by causing a light emitting element such as a light emitting diode to emit light using the power of the transmitted electric signal itself. There is a problem in that an impedance input circuit cannot be used, and impedance mismatching easily occurs. When impedance mismatch occurs, the quality of the transmitted electric signal deteriorates, and problems such as an increase in error rate in signal communication and a deterioration in transmission speed occur.

  Accordingly, an object of the present invention is to solve the above-mentioned problems and to suppress the erroneous disconnection of the communication cable by displaying the presence / absence of information communication, so that a general-purpose communication cable can be used and transmitted. An object of the present invention is to provide a cable signal detector in which deterioration of an electrical signal is small.

  The present invention was devised to achieve the above object, and is a cable signal detector for detecting the presence or absence of information communication in a communication cable, which is connected in series to the communication cable, and the communication cable is A rectifier circuit that branches and extracts a part of a signal to be transmitted, rectifies and outputs to direct current, and a light-emitting circuit that emits light by output from the rectifier circuit, the rectifier circuit being a half-wave rectifier circuit or a full-wave It is a cable signal detector configured by connecting a plurality of rectifier circuits in parallel.

  The communication cable transmits a differential signal, and the rectifier circuit having the same configuration may be connected in series to each of a pair of signal lines that transmit the differential signal. .

  Two rectifier circuits connected to each of the pair of signal lines may be connected in series, and the output thereof may be input to the light emitting circuit.

  As the communication cable, a cable including a plurality of signal lines including the pair of signal lines and a shield conductor that collectively covers the periphery of the plurality of signal lines may be used.

  A capacitor element or an inductive element for adjusting the input impedance may be connected in parallel with the rectifier circuit.

  The rectifier circuit and the light emitting circuit may be provided in a connector provided at an end of the communication cable or a relay connector to which the connector is connected.

  According to the present invention, it is possible to suppress erroneous disconnection of a communication cable by displaying the presence / absence of information communication, a general-purpose communication cable can be used, and a cable in which deterioration of an electric signal transmitted is small A signal detector can be provided.

(A) is a circuit diagram which shows an example of the transmission / reception system containing the cable signal detector which concerns on one Embodiment of this invention, (b) is a perspective view of the relay connector in which a cable signal detector is mounted. It is a reference diagram at the time of explaining the principle of the present invention, and is a circuit diagram of a transmission / reception system that does not include a rectifier circuit. It is a reference diagram at the time of explaining the principle of the present invention, and is a circuit diagram of a transmission / reception system when a rectifier circuit including one half-wave rectifier circuit is connected. In this invention, it is a circuit diagram of a rectifier circuit when N half-wave rectifier circuits are connected. In the present invention, it is a circuit diagram of a rectifier circuit when N full-wave rectifier circuits are connected. (A) is a circuit diagram explaining the parameters used in the simulation, and (b) is a graph showing the simulation result of the frequency characteristic of the reflection coefficient. It is a circuit diagram which shows an example of the transmission / reception system containing the cable signal detector which concerns on one Embodiment of this invention. It is a circuit diagram which shows an example of the transmission / reception system containing the cable signal detector which concerns on one modification of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1A is a circuit diagram showing an example of a transmission / reception system including a cable signal detector according to the present embodiment, and FIG. 1B is a perspective view of a relay connector on which the cable signal detector is mounted. .

  As shown in FIGS. 1A and 1B, the cable signal detector 1 detects the presence or absence of information communication in the communication cable 2 and is connected in series to the communication cable 2. Is provided with a rectifier circuit 3 for branching out a part of the signal transmitted by the rectifier, rectifying it into a direct current and outputting it, and a light emitting circuit 4 for emitting light by the output from the rectifier circuit 3.

  As the communication cable 2, a general-purpose LAN (Local Area Network) cable can be used. In the present embodiment, the communication cable 2 having four pairs (total of eight) of signal lines 2a for transmitting differential signals is used. In FIG. 1, only one pair of the four pairs of signal lines 2a is shown.

  The rectifier circuit 3 and the light emitting circuit 4 are provided in a connector (not shown) provided at an end of the communication cable 2 or a relay connector 10 to which the connector is connected. In the present embodiment, a case where the cable signal detector 1 is provided in the relay connector 10 will be described.

  The relay connector 10 includes two connectors 11 and connects the communication cables 2 connected to both the connectors 11. The connector 11 is, for example, a jack connector conforming to the RJ45 standard, and is configured to be connectable to a connector (for example, a plug connector conforming to the RJ45 standard) provided at the end of the communication cable 2.

  Both connectors 11 are mounted on a circuit board 12. The rectifier circuit 3 and the light emitting circuit 4 are mounted on the circuit board 12.

  In this embodiment, since the communication cable 2 having four pairs of signal lines 2a for transmitting differential signals is used, the circuit board 12 between the connectors 11 corresponds to four signal transmission pairs. A signal transmission unit 5 having a pair of transmission lines 6 is formed. In FIG. 1A, only a pair of transmission lines 6 is shown.

  In FIG. 1A, for the sake of simplicity of explanation, the transmission device 7 and the relay connector 10 are depicted as being directly connected. However, in actuality, the transmission device 7 and the relay connector 10 are connected to the communication cable 2. Connected through. Similarly, the relay connector 10 and the receiving device 8 are connected via the communication cable 2. In FIG. 1A, reference numeral 7a represents a transmission signal source, reference numeral 7b represents a transmission load, and reference numeral 8a represents a reception load.

  The rectifier circuit 3 is connected in series to an arbitrary signal line 2 a of the communication cable 2. Here, since the rectifier circuit 3 is mounted on the relay connector 10, the rectifier circuit 3 is inserted in series in the transmission line 6 formed on the circuit board 12. A specific configuration of the rectifier circuit 3 will be described later.

  The light emitting circuit 4 includes a light emitting diode as a light emitting element, and may be configured by a single light emitting diode. Note that the light emitting circuit 4 may include a resistor circuit, a current limiting circuit that limits a current flowing through the light emitting diode, and the like as appropriate.

  In the cable signal detector 1 according to the present embodiment, the rectifier circuit 3 is configured by connecting a plurality of half-wave rectifier circuits or multiple full-wave rectifier circuits in parallel.

  That is, the rectifier circuit 3 performs the rectification function as a whole, but its specific configuration is generally a circuit generally called a half-wave rectifier circuit or a full-wave rectifier circuit (hereinafter referred to as a sub-rectifier circuit 9 and Are connected in parallel. In FIG. 1A, the rectifier circuit 3 includes a first sub-rectifier circuit 9a formed of a half-wave rectifier circuit and a second sub-rectifier circuit 9b formed of a half-end rectifier circuit having the same configuration as the first sub-rectifier circuit 9a in parallel. Connected to and configured. The sub-rectifier circuits 9a and 9b may have different configurations. FIG. 1A shows a case where the sub rectifier circuits 9a and 9b are composed of two diodes D and two capacitive elements C for cutting direct current. The specific configuration is not limited to this.

  Hereinafter, the reason why the sub-rectifier circuits 9a and 9b are connected in parallel will be described.

  By using the rectifier circuit 3, it is possible to operate the light emitting circuit 4 by obtaining DC power from the signal line 2a for transmitting a high-frequency electric signal such as a digital signal. However, in this case, it is necessary to connect the rectifier circuit 3 to the signal line 2a of the communication cable 2 in series, which may cause impedance mismatch in the transmission / reception system. Impedance mismatch is a problem because it causes degradation of the transmitted electrical signal.

Here, there is a reflection coefficient Γ as an index representing the matching state of the electric signal. For example, when the signal line 2a and the transmission device 7 are connected, the reflection coefficient Γ at the connection point between the signal line 2a and the transmission device 7 is assumed that the input impedance of the signal line 2a is Za and the input impedance of the transmission device 7 is Zb. The following formula Γ = (Zb−Za) / (Zb + Za)
It is prescribed by.

At this time, if the power of the signal sent from the transmission device 7 is P, the power P ′ transmitted to the signal line 2a is expressed by the following equation: P ′ = P × (1− | Γ | ² )
It becomes.

  That is, when the difference between Za and Zb is large (in the case of mismatch), the absolute value (| Γ |) of the reflection coefficient Γ is large (the matching state is deteriorated), and the signal intensity transmitted to the signal line 2a is small. turn into. For this reason, by making Za and Zb substantially the same value and making the reflection coefficient Γ substantially 0, a good matching state can be maintained.

First, as shown in FIG. 2, consider a case where a transmission device 7 and a reception device 8 are connected by a communication cable 2. When the characteristic impedance of the signal line 2a is Z1, and the impedance of the loads 7b and 8a of the transmission device 7 and the reception device 8 is Z1, at the signal input end (the connection point between the transmission device 7 and the signal line 2a, the observation point A shown in the figure). The reflection coefficient ΓA of the following equation is ΓA = (Z1−Z1) / (Z1 + Z1) = 0
| ΓA | = 0
Thus, the transmission device 7 and the signal line 2a are perfectly matched.

Next, as shown in FIG. 3, the case where the rectifier circuit 3 provided with one sub-rectifier circuit 9 is connected in series to the signal line 2a is considered. When the characteristic impedance of the signal line 2a is Z1, the impedance of the loads 7b and 8a of the transmission device 7 and the reception device 8 is Z1, and the input impedance of the rectifier circuit 3 is ZR, the signal line input terminal (the rectifier circuit 3 and the signal line 2a The reflection coefficient ΓB at the connection point to the observation point B shown in the figure is expressed by the following equation: ΓB = ((Z1 + ZR) −Z1) / ((Z1 + ZR) + Z1)
= ZR / (2 × Z1 + ZR)
= 1 / (2 × Z1 / ZR + 1)
It becomes. That is, it can be seen that by inserting the rectifier circuit 3, | ΓB |> 0, and the matching state deteriorates. Here, the reflection coefficient ΓB depends on the ratio of Z1 and ZR, and it can be said that the smaller the ZR with respect to Z1, the better the matching state.

In FIG. 3, the light emitting circuit 4 is connected to the output terminal of the rectifier circuit 3. Part of the high-frequency signal input to the rectifier circuit 3 is converted into a DC signal by the diode D and transmitted to the light emitting circuit 4. Here, assuming that the operating resistance of the diode D is rdΩ, the non-operating resistance is infinite Ω, and the impedance of the light emitting circuit 4 serving as a load is sufficiently larger than rd, the input impedance (rectification) of the rectifying circuit 3 in FIG. The input impedance viewed from the input terminal of the circuit 3 is rd. Therefore, the reflection coefficient ΓB at the observation point B is expressed by the following equation: ΓB = 1 / (2 × Z1 / rd + 1)
It is represented by Assuming that Z1 is a real number, the following formula: | ΓB | = 1 / (2 × Z1 / rd + 1)
It becomes.

Furthermore, for the simplification of the equation, when Z1 / rd >> 1 is processed, | ΓB | is expressed by the following equation: | ΓB | = rd / (2 × Z1)
Can be approximated by

Next, consider the cable signal detector 1 according to the present embodiment shown in FIG. In the cable signal detector 1, two sub rectifier circuits 9a and 9b are connected in parallel, and the input impedance of each sub rectifier circuit 9a and 9b is rd. (Input impedance viewed from the input terminal 3) is rd / 2. At this time, the absolute value | ΓC | of the reflection coefficient ΓC at the observation point C in FIG. 1A is expressed by the following expression: | ΓC | = rd / (4 × Z1)
It is represented by That is, by connecting the two sub-rectifier circuits 9a and 9b in parallel to form the rectifier circuit 3, compared to the case where the rectifier circuit 3 is configured by one sub-rectifier circuit 9 (in the case of FIG. 3), The reflection coefficient can be halved.

  In the present embodiment, the two rectifier circuits 9a and 9b are connected in parallel to configure the rectifier circuit 3. However, the number of the sub rectifier circuits 9 to be paralleled in the rectifier circuit 3 is not limited to this. Absent.

For example, as shown in FIG. 4, when N sub-rectifier circuits 9a, 9b,..., 9n are connected in parallel, the input impedance of the entire rectifier circuit 3 is rd / N. If the reflection coefficient at the observation point C at this time is ΓCN, | ΓCN | is expressed by the following equation: | ΓCN | = rd / (2N × Z1)
It is represented by That is, the N rectifier circuits 9a, 9b,..., 9n are connected in parallel to configure the rectifier circuit 3, compared to the case where the rectifier circuit 3 is configured by one sub rectifier circuit 9. The reflection coefficient can be reduced to 1 / N.

  As described above, as the number of the sub-rectifier circuits 9 arranged in parallel in the rectifier circuit 3 is increased, it is possible to reduce the reflection coefficient and improve the impedance matching state. However, since the cost increases when the number of sub-rectifier circuits 9 is increased, the number of sub-rectifier circuits 9 to be arranged in parallel may be appropriately determined according to the required quality of the electrical signal.

  In the present embodiment, a half-wave rectifier circuit is used as the sub-rectifier circuit 9, but a full-wave rectifier circuit may be used as the sub-rectifier circuit 9 as shown in FIG.

  For confirmation, when a full-wave rectifier circuit is used as the sub-rectifier circuit 9 and each parameter is set as shown in FIG. 6A, the number (stage number) of the sub-rectifier circuits 9 in parallel is changed. The frequency characteristic of the reflection coefficient is shown in FIG.

  As shown in FIG. 6B, the reflection coefficient decreases as the number of stages of the sub-rectifier circuit 9 increases, and it can be seen that the impedance matching state can be improved as the number of stages of the sub-rectifier circuit 9 is increased.

  As described above, the cable signal detector 1 according to the present embodiment is connected in series to the communication cable 2, branches a part of the signal transmitted by the communication cable 2, takes it out, rectifies it into direct current, and outputs it. And a light emitting circuit 4 that emits light in response to an output from the rectifier circuit 3. The rectifier circuit 3 includes a plurality of half-wave rectifier circuits or full-wave rectifier circuits (sub-rectifier circuits 9) connected in parallel. It is configured.

  By configuring in this way, it is possible to display the presence / absence of information communication of the communication cable 2 based on the presence / absence of light emission of the light emitting circuit 4, and it is possible to suppress erroneous disconnection of the communication cable 2.

  Moreover, in this embodiment, since there is no need to provide a monitoring signal line or the like in the communication cable 2 as in the prior art, a general-purpose cable can be used as the communication cable 2 and the cost is low.

  Furthermore, by configuring the rectifier circuit 3 by connecting a plurality of sub-rectifier circuits 9 in parallel, it becomes possible to reduce the input impedance of the rectifier circuit 3, suppress the reflection coefficient, and realize good impedance matching. . As a result, it is possible to suppress degradation in the quality of the transmitted electrical signal, increase in error rate in signal communication, degradation in transmission speed, and the like.

  That is, according to the present embodiment, it is possible to suppress erroneous disconnection of the communication cable 2 by displaying the presence / absence of information communication, the general-purpose communication cable 2 can be used, and the transmitted electrical signal Therefore, it is possible to realize the cable signal detector 1 with a small deterioration.

  In the present embodiment, since the light emitting circuit 4 is configured to emit light using only the power of the signal extracted from the communication cable 2 without using an external power source, a battery, an amplifier circuit, or the like, There is no influence of the noise caused, and problems such as crosstalk due to the output voltage of the amplifier circuit do not occur.

  Next, another embodiment of the present invention will be described.

  The cable signal detector 71 shown in FIG. 7 is configured such that the rectifier circuit 3 having the same configuration is connected in series to each of a pair of signal lines 2a that transmit differential signals. Although not shown, both rectifier circuits 3 are configured by connecting a plurality of sub-rectifier circuits 9 in parallel.

  In the cable signal detector 1 described with reference to FIG. 1A, the rectifier circuit 3 is connected only to one signal line 2a of a pair of signal lines 2a for transmitting a differential signal. It is also conceivable that a difference in electrical signal propagation time between 2a, that is, a skew occurs. When a UTP cable or the like that does not have a shield conductor is used as the communication cable 2, the effect of this skew is small. However, when an STP cable or the like in which the periphery of the plurality of signal lines 2a is collectively covered with a shield conductor is used. In other cases, the deterioration of the electric signal due to the influence of the skew may be a problem.

  In the cable signal detector 71, since the rectifier circuit 3 having the same configuration is connected to each of the pair of signal lines 2a that transmit the differential signal, it is possible to suppress the occurrence of skew within the pair. This is particularly suitable when a communication cable 2 having a shield conductor such as an STP cable is used.

  The cable signal detector 71 is configured to connect two rectifier circuits 3 connected to each of the pair of signal lines 2 a in series and to input the output to the light emitting circuit 4. Thereby, even if the electric power taken out by both rectifier circuits 3 is small, it becomes possible to operate the light emitting circuit 4 stably.

  The present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the spirit of the present invention.

  For example, although not mentioned in the above embodiment, as shown in FIG. 8, a capacitor element Ca or an inductive element La for adjusting the input impedance on the rectifier circuit 3 side may be connected in parallel with the rectifier circuit 3. Good. Although FIG. 8 shows the case where the capacitive element Ca and the inductive element La are connected in parallel with the rectifier circuit 3, only one of them may be used, and the capacitive element Ca and the inductive element La are connected in series. It may be provided in parallel with the rectifier circuit 3. In this case, a part of the transmitted electrical signal does not pass through the rectifier circuit 3 but flows downstream through the capacitive element Ca and the inductive element La, and thus the light emitting circuit through the rectifier circuit 3. The power output to 4 decreases. Therefore, it is preferable to use the configuration of FIG. 8 in order to further improve the matching state when sufficient power is obtained in the light emitting circuit 4.

DESCRIPTION OF SYMBOLS 1 Cable signal detector 2 Communication cable 3 Rectifier circuit 4 Light emission circuit 7 Transmitter 8 Receiver 9 Sub rectifier circuit

Claims (6)

A cable signal detector for detecting the presence or absence of information communication in a communication cable,
A rectifier circuit connected in series to the communication cable, branching out a part of a signal transmitted by the communication cable, and rectifying and outputting to direct current;
A light emitting circuit that emits light by an output from the rectifier circuit,
The rectifier circuit is configured by connecting a plurality of half-wave rectifier circuits or a plurality of full-wave rectifier circuits in parallel. The communication cable transmits a differential signal;
The cable signal detector according to claim 1, wherein the rectifier circuit having the same configuration is connected in series to each of a pair of signal lines that transmit a differential signal. The cable signal detector according to claim 2, wherein the two rectifier circuits connected to each of the pair of signal lines are connected in series, and an output thereof is input to the light emitting circuit. The cable according to claim 2 or 3, wherein the communication cable includes a plurality of signal lines including the pair of signal lines and a shield conductor that collectively covers the periphery of the plurality of signal lines. Signal detector. The cable signal detector according to claim 1, wherein a capacitive element or an inductive element for adjusting input impedance is connected in parallel with the rectifier circuit. The cable signal detector according to claim 1, wherein the rectifier circuit and the light emitting circuit are provided on a connector provided at an end of the communication cable or a relay connector to which the connector is connected.

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