JP2012100191A - Switching device for cable communication, and power line wiring structure and electric apparatus having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress an increases in transmission loss and generation of unwanted radiation.SOLUTION: A switch device 5 includes switches 5a and 5b connected with branch lines 31 and 32. The switches 5a and 5b interlocks with each other to selectively use either of a state where the branch lines 31 and 32 are connected with electric apparatus wiring 81 and 82 or a state where the branch lines 31 and 32 are connected with a termination circuit 6.

Description

  The present invention relates to a switch device for wired communication using two communication lines, a power line wiring structure having the switch device, and an electric device.

  Wired communication is performed by placing a signal on a carrier wave in a certain frequency band. For example, power line carrier communication (PLC), which is one type of wired communication, performs communication using a power line that supplies power as a transmission path. In indoor power line communication, transmission and reception are performed between communication devices connected to the power wiring. Is called.

  Conventionally, a switch is installed on a wall or the like in an electric device such as a lighting fixture or a ventilation fan, and the on / off of the electric device is controlled by the switch. For example, in Patent Document 1, such switches are provided at a plurality of locations. A configuration example of a conventional switch is shown in FIG. In FIG. 9, a branch circuit 94 is provided on the main line 2 of the power source, and branch lines 93 a and 93 b branch from the main line 2 in the branch circuit 94. The Hi line 21 of the trunk line 2 is connected to the main body 9 of the electric device via the branch line 93a, the switch 95 and the wiring 98, and the Lo line 22 of the main line 2 is connected to the electric device main body 9 via the branch line 93b. Connected directly.

Japanese Patent Laid-Open No. 7-21869

  In the conventional example shown in FIG. 9, a line composed of branch lines 93 a and 93 b branching from the branch circuit 94 to the electric device main body 9 and the wiring 98 is a stub circuit for the trunk line 2. The stub circuit is terminated by the impedance of the electric device body 9 when the switch is turned on, and is open when the switch is turned off. In the open stub state when the switch is off, there is a problem that a resonance state is generated by the stub circuit and transmission loss increases in the communication frequency band.

  The stub length when the switch is turned on corresponds to the length between ABKs in FIG. 9 on the main line 21 side, and corresponds to the length between DKs on the main line 22 side. On the other hand, the stub length at the time of switch-off corresponds to the length between AB on the main line 21 side, and corresponds to the length between DK on the main line 22 side. In wired communication such as PLC, if the lengths of the Hi line and Lo line of the cable are not equal, the balance of the cable is lost and unnecessary radiation occurs. In the above conventional example, (a) the length between the ABKs when the switch is turned on and the length between the DKs are the same, and (b) the length between the ABs when the switch is turned off and the length between the DKs are the same. Both cannot be realized at the same time. Therefore, the conventional example has a problem that the stub circuit causes unnecessary radiation in wired communication such as PLC.

  An object of the present invention is to solve such a conventional problem, a switch device for wired communication capable of suppressing an increase in transmission loss and suppressing the occurrence of unnecessary radiation, and a power line having the same. It is to provide a wiring structure and an electric device.

  The switch device according to the present invention is a switch device for wired communication made through first and second communication lines, a termination circuit connected to the first and second communication lines, and a main body of an electric device. A first switch that selectively takes a state in which the first communication line connected to the first communication line is connected to the first communication line and a state in which the first communication line is connected to one terminal of the termination circuit And a state in which the second wiring connected to the main body of the electric device and the second communication line are connected, and a state in which the second communication line and the other terminal of the termination circuit are connected. A first switch that takes a state in which the first and second communication lines are connected to both terminals of the termination circuit, respectively. And the first and second communication lines and the first and second wirings, respectively. A state of taking selectively a second operation mode taken by the first and second switches.

  According to the switch device of the present invention, the on / off state (first and second operation modes) of the connection between the first and second communication lines and the main body of the electronic device via the first and second wirings is changed. The first and second switches are switched. Therefore, (a) the total length of the first communication line and the first wiring is the same as the total length of the second communication line and the second wiring in the switch-on state. (B) Both the lengths of the first communication line and the second communication line can be realized simultaneously in the switch-off state. For this reason, it is possible to realize a configuration in which the degree of balance is high and unnecessary radiation hardly occurs. In the switch-off state, the transmission loss of wired communication is unlikely to increase due to the termination circuit.

  In the present invention, the termination circuit matches the characteristic impedance of the first and second communication lines at the frequency of the carrier wave used for communication, and cuts off the applied power between the first and second communication lines. It is preferable to do. According to this, it is possible to realize a configuration that terminates properly and does not consume power unnecessarily in the switch-off state.

  In the present invention, it is preferable that the termination circuit includes a circuit in which a capacitor and a resistor are connected in series. According to this, it is possible to realize a termination circuit that appropriately cuts a low frequency band used for power supply.

  Moreover, in this invention, it is preferable that the value which divided the resistance value of the said resistor by the characteristic impedance of the said 1st and 2nd communication line is 0.8 or more and 1.3 or less. According to this, it is possible to realize a termination circuit in which an increase in transmission loss is suppressed to a predetermined degree.

  In the present invention, the termination circuit may include a circuit in which a first capacitor, a resistor, and a second capacitor having the same capacitance value as the first capacitor are connected in series in this order. preferable. According to this, it is possible to improve the balance of the circuit configuration that may cause unnecessary radiation in the termination circuit.

  In the present invention, the termination circuit includes a circuit in which a first resistor, a capacitor, and a second resistor having the same resistance value as the first resistor are connected in series in this order. It is preferable. According to this, it is possible to improve the balance of the circuit configuration that may cause unnecessary radiation in the termination circuit.

  In the present invention, a value obtained by dividing twice the resistance value of the second resistor by the characteristic impedance of the first and second communication lines is 0.8 or more and 1.3 or less. Is preferred. According to this, it is possible to realize a termination circuit in which an increase in transmission loss is suppressed to a predetermined degree.

  In the present invention, it is preferable that the termination circuit includes a circuit in which a capacitor and a variable resistor are connected in series. According to this, even if cables having different characteristic impedances are used as the first and second communication lines, the resistance value of the variable resistor can be adjusted, so that the termination circuit is optimally matched according to the cable. Can do.

  A power line wiring structure according to another aspect of the present invention includes the above-described switch device for wired communication, the first and second communication trunk lines, the first and second communication lines, and the first and first communication lines. And the first and second communication lines are branched from the first and second communication trunk lines, respectively, and the first and second communication lines are the same as each other. The first and second electrical equipment wires have the same length. According to this, (a) when the switch is on, the total length of the first communication line and the first wiring is the same as the total length of the second communication line and the second wiring. And (b) the power line wiring structure having both the first communication line and the second communication line have the same length in the switch-off state.

  In addition, the present invention may be realized as an electric device such as a lighting fixture or a ventilation fan incorporating the above-described switch device.

1 is a circuit diagram showing a schematic configuration of a power line communication system according to an embodiment of the present invention. FIG. 2 is a circuit diagram illustrating a branch portion of FIG. 1 when an interlocking switch is in an off state. FIG. 3 is a graph showing the dependence of transmission loss increase ΔS21 on R1 / Zo in the termination circuits of FIGS. 1 and 2; FIG. It is a circuit diagram of the simulation circuit which comprised this Embodiment and the prior art example in simulation. It is a graph which shows the result of having measured the unnecessary radiation which generate | occur | produces when communicating between PLC communication apparatuses in the simulation circuit which concerns on a prior art example. It is a graph which shows the result of having measured the unnecessary radiation which generate | occur | produces when communicating between PLC communication apparatuses in the simulation circuit which concerns on this Embodiment. It is a modification of a termination circuit. It is another modification of a termination circuit. This is still another modification of the termination circuit. It is a circuit diagram of the prior art example of a switch apparatus.

  Hereinafter, a power line communication system 1 according to a first embodiment which is an embodiment of the present invention will be described with reference to FIG. The trunk line 2 having the Hi line 21 and the Lo line 22 (first and second communication trunk lines) is connected to a power source that is a power transmission source. In FIG. 1, in order to easily distinguish the Hi side and the Lo side in the entire wiring, the Hi side is indicated by a thick line and the Lo side is indicated by a thin line. A plurality of branch lines are provided from the main line 2, and various electric devices are connected to each branch line. Electric power from the main line 2 is supplied to these electric devices via a branch line. Further, the electrical devices connected to the branch line are configured to be able to perform wired communication using the PLC (power line carrier communication) system via the branch line and the main line 2. A frequency band different from a frequency band (for example, a frequency band from DC to 60 Hz) used for power supply is used for the communication carrier wave. As one of the branch structures as described above, a branch circuit 4 is provided on the main line 2, and a branch line 3 is branched therefrom. The branch line 3 has a branch line 31 (first communication line) connected to the Hi line 21 and a branch line 32 (second communication line) connected to the Lo line 22. The branch line 3 is connected to the electric device main body 9 via the switch device 7. The electric device main body 9 is various electric devices such as lighting fixtures, and is connected to the terminals 8a and 8b via electric device wirings 81 and 82 (first and second electric device wirings), respectively.

  The switch device 7 includes an interlocking switch 5 and a termination circuit 6. The termination circuit 6 includes a capacitor C1 that does not pass a frequency band of a power source, for example, a frequency band from DC to 60 Hz, and a resistor R1 that matches a characteristic impedance of a cable used for the branch line 3. In the following, when the symbols “C1”, “C2”, “R1”, “R2”, etc. are described alone, they represent the capacitance of the capacitors C1 and C2 and the resistance values of the resistors R1 and R2. The capacitor C1 and the resistor R1 are connected in series with each other and are connected to the terminals 6a and 6b. The interlocking switch 5 has switches 5a and 5b. The switch 5a selectively takes a state in which the branch line 31 and the terminal 8a are connected and a state in which the branch line 31 and the terminal 6a are connected. The switch 5b selectively takes a state in which the branch line 32 and the terminal 8b are connected and a state in which the branch line 32 and the terminal 6b are connected. The switches 5a and 5b are configured to interlock with each other. Specifically, the switches 5a and 5b are connected to the branch lines 31 and 32 and the terminals 8a and 8b, respectively, to turn on the electrical device body 9, and to the branch lines 31 and 32 and the terminals 6a and 6b. Are connected to each other so as to be switched to an off state in which the electric device main body 9 is turned off.

  In the above configuration, when the interlock switch 5 is turned on, the electric device main body 9 is connected to the main line 2 via the electric device wirings 81 and 82, the switch device 7, and the branch line 3. Thereby, the electric power from the main line 2 is supplied to the electric equipment main body 9, and the electric equipment main body 9 operates. At this time, the branch line 3 is terminated by the impedance of the electric device main body 9. On the other hand, when the interlock switch 5 is turned off, power is not supplied to the electric device main body 9, and the operation of the electric device main body 9 is stopped. At this time, since the branch line 3 is terminated by the termination circuit 6, an open termination (open stub) state that causes stub resonance in wired communication performed via the trunk line 2 is avoided. For this reason, an increase in transmission loss in wired communication can be suppressed.

  FIG. 2 is a circuit diagram showing the branch portion of FIG. 1 when the interlocking switch 5 is in the OFF state. The transmission characteristic S21 in the S parameter of this circuit and the impedance Z of the main line 2 viewed from the stub side (branch line 3 side) are expressed as follows. Here, Zo is the characteristic impedance of the cable used for the branch line 3, and Zs is the impedance of the termination circuit 6. Θ is the electrical length of the branch line 3. j represents an imaginary unit.

  S21 = 1 / {1 + Zo / (2 * Z)}, Z = (Zs * cos θ + j * Zo * sin θ) / (cos θ + j * (Zs / Zo) * sin θ)

  The transmission loss in the stub circuit is greatest when θ = 90 ° or θ = 180 ° at which the stub is in a resonance state. S21 in each of these cases is as follows. Note that S21 when θ = 90 ° is S21 (90 °), and S21 when θ = 180 ° is S21 (180 °).

  S21 (90 °) = 1 / {1 + Zs / (2 * Zo)}, S21 (180 °) = 1 / {1 + Zo / (2 * Zs)}

  In order to reduce the transmission loss S21 in the frequency band used for communication, the end of the stub may be matched with the characteristic impedance of the stub cable, that is, Zs = Zo. When the branch line 3 is terminated so as to be impedance-matched, the input signal to the branch circuit 4 is equally distributed in two output directions, and the frequency characteristics are flattened. On the other hand, the impedance Zs of the termination circuit 6 is expressed by Zs = R1 + 1 / (j * ω * C1). Since C1 is provided for the purpose of cutting the power supply frequency, the influence of C1 is not effective in the frequency band used for communication. Selected to be negligible. Therefore, in the frequency band used for communication, the relationship is Zs≈R1. R1 is adjusted to R1 = Zo so that the branch line 3 terminates while impedance matching.

  Here, let us consider a case where R1 / Zo slightly varies from R1 / Zo = 1 where the termination is impedance matched (hereinafter referred to as “matching termination”). As R1 / Zo deviates from the matching termination, transmission loss increases. Assuming that R1 slightly deviates from the state satisfying R1 / Zo = 1, the transmission loss increase ΔS21 when R1 / Zo deviates from the matching termination is expressed as follows. Note that ΔS21 when θ = 90 ° is ΔS21 (90 °), and ΔS21 when θ = 180 ° is ΔS21 (180 °). | X | represents the absolute value of x.

ΔS21 (90 °) = | 20 * log ₁₀ [1 / {1 + R1 / (2 * Zo)}] − 20 * log ₁₀ {1 / (1 + 1/2)} |

ΔS21 (180 °) = | 20 * log ₁₀ [1 / {1 + Zo / (2 * R1)}] − 20 * log ₁₀ {1 / (1 + 1/2)} |

  FIG. 3 shows the dependence of ΔS21 (90 °) and ΔS21 (180 °) on R1 / Zo. From FIG. 3, it can be seen that R1 / Zo should be in the range of 0.8 to 1.3 in order to suppress the increase in loss to 1 dB or less. As described above, even when R1 / Zo slightly varies from the matching termination state, an increase in transmission loss is suppressed.

  On the other hand, as shown in FIG. 1, the stub length when the interlocking switch 5 is in the ON state is the length from the terminal 4a through the terminal 8a to the terminal 9a (hereinafter referred to as “length L1”). The Lo wire 22 side corresponds to the length from the terminal 4b through the terminal 8b to the terminal 9b (hereinafter referred to as “length L2”). The stub length when the interlocking switch 5 is in the OFF state corresponds to the length from the terminal 4a to the terminal 6a on the Hi line 21 side (hereinafter referred to as “length L3”), and the Lo line 22 side is the terminal. This corresponds to the length from 4b to the terminal 6b (hereinafter referred to as “length L4”). At this time, it is possible to set L1 = L2 and L3 = L4. Therefore, the present embodiment is configured such that L1 = L2 and L3 = L4. With such a configuration, the stub length of the line on the Hi line 21 side is equal to the stub length of the line on the Lo line 22 side both when the switch is turned on and off, and the stub circuit can be balanced. .

  FIG. 4A to FIG. 4C show simulation circuits 110 to 130 configured to simulate this embodiment and the conventional example. Each of the simulation circuits 110 to 130 is a communication circuit that connects the PLC communication devices 141 and 142. The PLC communicators 141 and 142 communicate by the PLC method via the simulation circuits 110-130. The simulation circuit 110 corresponds to a configuration obtained by extracting the trunk line 2 and the branch line 3 in the present embodiment, and as illustrated in FIG. 4A, the communication trunk lines 111 and 112 and the branch lines 113 and 114. Consists of. The branch lines 113 and 114 are arranged at positions separated from the PLC communication devices 141 and 142 by La and Lb, respectively, and both have a length of Lc.

  The simulation circuit 120 corresponds to the conventional example of FIG. 9 and includes communication trunk lines 121 and 122, a protrusion 123, and a switch 124. The protruding portion 123 is a portion where the communication trunk line 122 is protruded by the length of Lc at positions separated from the PLC communication devices 141 and 142 by La and Lb, respectively. The switch 124 is provided in the middle of the protruding portion 123 and is in an on state. The protrusion 123 corresponds to the stub circuit including the branch lines 93 a and 93 b and the wiring 98 provided for installing the switch 95 in the conventional example of FIG. 9.

  As shown in FIG. 4C, the simulation circuit 130 corresponds to the present embodiment of FIG. 1, and includes communication trunk lines 131 and 132, protrusions 133 and 134, a switch 135 and a switch 136, and wirings 137 and 138. Consists of. The protruding portion 133 and the protruding portion 134 are portions where the communication trunk lines 131 and 132 are protruded by the length of Lc, respectively, at positions separated from the PLC communication devices 141 and 142 by La and Lb, respectively. The switches 135 and 136 are provided in the middle of the protrusions 133 and 134, respectively, and both are in the on state. The protrusions 133 and 134 correspond to a stub circuit that is provided for installing the switches 5a and 5b and that includes the branch line 3 and the electric device wirings 81 and 82.

  FIGS. 5A and 5B show the results of measuring unwanted radiation generated when communication is performed between the PLC communication devices 141 and 142 in the simulation circuits 110 to 130 while changing the communication frequency. . In this measurement, La = Lb = 3 m, Lc = 1.5 m, and unnecessary at a position 3 m away from the position corresponding to the branch position in each simulation circuit (the position surrounded by the broken line in FIG. 4) in the opposite direction to Lc. Radiation was measured. The cable used for the communication trunk line 111 or the like is VVF (vinyl insulated vinyl sheath cable flat type) φ1.6 mm. 5A and 5B, the horizontal axis indicates the communication frequency, and the vertical axis indicates the electric field strength in the unwanted radiation. The broken lines g1 to g3 correspond to the simulation circuits 110, 120, and 130, respectively. A broken line g1 indicates unnecessary radiation from the simulation circuit 110, that is, unnecessary radiation generated due to the presence of the branch line itself. In the simulation circuit 120, since the switch is inserted into only one line in the branch cable, the lengths of the communication trunk lines 121 and 122 are not the same. For this reason, as indicated by the broken line g2, unnecessary radiation is increased as compared with the simulation circuit 110 having the two branch lines 113 and 114 having the same length. On the other hand, in the simulation circuit 130, the communication trunk lines 131 and 132 have the same length by inserting switches in both lines of the cable in a balanced manner. For this reason, as shown by the broken line g3, there is no increase in unnecessary radiation as compared with the simulation circuit 110.

  As described above, according to the present embodiment, it is understood that an increase in unnecessary radiation caused by the switch can be suppressed. Further, as described above, in the stub circuit of FIG. 1, when the interlock switch 5 is in the on state, one stub length L1 is equal to the other stub length L2, and when the interlock switch 5 is in the off state. One stub length L3 is equal to the other stub length L4. Therefore, regardless of the state of the interlock switch 5, a circuit in which the balance of the stub circuit is high and unnecessary radiation hardly occurs is realized.

(First modification of termination circuit)
Hereinafter, modifications of the termination circuit 6 in the present embodiment will be described. FIG. 6 shows a termination circuit 61 according to the first modification. The termination circuit 61 is a circuit in which a capacitor C2, a resistor R1, and a capacitor C2 are connected in series in this order, and satisfies the relationship C2 = C1 * 2. In the termination circuit 6, the path through which the signal passes differs depending on whether the signal travels from the branch line 31 to the branch line 32 or vice versa, which may cause a loss of balance and cause unnecessary radiation. On the other hand, according to the termination circuit 61, the impedance is the same as that of the termination circuit 6, and the configuration when viewed from the branch line 31 is the same as the configuration when viewed from the branch line 32. Can be improved.

(Second modification of termination circuit)
FIG. 7 shows a termination circuit 62 according to the second modification. The termination circuit 62 is a circuit in which a resistor R2, a capacitor C1, and a resistor R2 are connected in series in this order, and satisfies the relationship R2 = R1 / 2. According to the termination circuit 62, since the impedance is the same as that of the termination circuit 6 and the configuration viewed from the branch line 31 is the same as the configuration viewed from the branch line 32, the circuit configuration is the same as the termination circuit 61. Can improve the balance. As described above, in order to suppress the increase in transmission loss to 1 dB or less, R1 / Zo only needs to be in the range of 0.8 to 1.3. Therefore, in this modification, 2 * R2 / Zo only needs to be in the range of 0.8 to 1.3.

(Third Modification of Termination Circuit)
FIG. 8 shows a termination circuit 63 according to a third modification. The termination circuit 63 is a circuit in which a capacitor C1 and a variable resistor R3 are connected in series. By adjusting the resistance value of the variable resistor R <b> 3, even if cables having different characteristic impedances are used as the branch line 3, it is possible to achieve termination that is optimally matched in the termination circuit 63.

<Modification>
The above is a description of a preferred embodiment of the present invention, but the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope described in the means for solving the problem. It is possible.

  For example, in the above-described embodiment, PLC is assumed as a wired communication method, but other communication methods may be assumed.

  In the above-described embodiment, the interlock switch 5 and the electric device main body 9 are connected via the electric device wirings 81 and 82. Here, the interlocking switch 5 may be built in an electric device or may be installed on a wall or the like.

DESCRIPTION OF SYMBOLS 1 Power line communication system 3 Branch line 5 Interlocking switch 5a Switch 5b Switch 6 Termination circuit 9 Electric equipment main body 2 Trunk line

Claims (10)

A switch device for wired communication made via first and second communication lines,
A termination circuit connected to the first and second communication lines;
A state in which the first electric device wiring connected to the main body of the electric device and the first communication line are connected and a state in which the first communication line and one terminal of the termination circuit are connected are selectively used. A first switch to take
A state in which the second electric equipment wiring connected to the main body of the electric equipment is connected to the second communication line and a state in which the second communication line is connected to the other terminal of the termination circuit are selectively used. And a second switch to take
A first operation mode in which the first and second switches take a state of connecting the first and second communication lines and both terminals of the termination circuit, respectively; and the first and second communication lines; A switch device for wired communication, which selectively takes a second operation mode in which the first and second switches are connected to connect the first and second electrical equipment wirings, respectively. .   The termination circuit is matched with the characteristic impedance of the first and second communication lines at the frequency of a carrier wave used for communication, and cuts off the applied power between the first and second communication lines. The switch device for wired communication according to claim 1.   The switch device for wired communication according to claim 2, wherein the termination circuit includes a circuit in which a capacitor and a resistor are connected in series.   The wired communication according to claim 3, wherein a value obtained by dividing the resistance value of the resistor by the characteristic impedance of the first and second communication lines is 0.8 or more and 1.3 or less. Switch device.   4. The termination circuit includes a circuit in which a first capacitor, a resistor, and a second capacitor having the same capacitance value as the first capacitor are connected in series in this order. Switch device for wired communication as described in 1.   The termination circuit includes a circuit in which a first resistor, a capacitor, and a second resistor having the same resistance value as the first resistor are connected in series in this order. Item 4. The switch device for wired communication according to Item 3.   The value obtained by dividing twice the resistance value of the second resistor by the characteristic impedance of the first and second communication lines is 0.8 or more and 1.3 or less. 6. The switch device for wired communication according to 6.   The switch device for wired communication according to claim 2, wherein the termination circuit includes a circuit in which a capacitor and a variable resistor are connected in series. A switch device for wired communication according to any one of claims 1 to 8,
First and second communication trunk lines;
The first and second communication lines;
The first and second electrical equipment wiring,
The first and second communication lines branch off from the first and second communication trunk lines, respectively;
The first and second communication lines have the same length;
The power line wiring structure for wired communication, wherein the first and second electric equipment wirings have the same length.   An electric device incorporating the switch device for wired communication according to any one of claims 1 to 8.

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