JP2003264807A - Ac/dc converter with surge protective function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To protect subscriber equipment from a lightning surge. <P>SOLUTION: Arresters 12a, 12b are provided between an AC line 19a, 19b and a ground line 20, respectively. The ground line 20 is connected by using a clip 22 to an outer conductor of a line terminal 30 of a cable MODEM 105 to which a CATV transmission line of a protector side is connected. Thus, a surge intruded to the AC two lines 19a, 19b is bypassed to ground via the arresters 12a, 12b, the ground line 20, the line terminal 30, an outer conductor of the CATV transmission line 125, and earth of the protector. Consequently, the subscriber equipment such as the cable MODEM 105 can be protected from the surge intruded from the AC power lines. Then a rectifier circuit 23 applies DC feeding to the cable MODEM 105. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a surge protection function of supplying DC power to a home device connected to a CATV transmission line and protecting the home device from surge noise such as lightning surge intruding from a power line. It relates to an AC / DC converter.

[0002]

2. Description of the Related Art Conventionally, there has been a problem that communication devices, which are domestic devices, are destroyed by a lightning surge. For example, there is the CATV data communication system shown in FIG. This is a system in which computer device 100 is connected to a CATV transmission line to perform bidirectional data communication. The computer device 100 includes a cable modem 105 and a coaxial cable 12.
5, the wall unit 110, and the protector 115 are connected to an external CATV transmission line. In this conventional system, the power supply line 130 is used as a common power supply line, and at least the housing of the cable modem 105 is grounded via the protector 115 by the outer conductor of the coaxial cable 125.

When there is a lightning strike in the vicinity of this system, the computer device 100 and the cable modem 105 are connected to the commercial power source 130, and a surge enters through the commercial power source 130 as shown in FIG. Then, the surge is discharged into the housing of the communication device which is a home device, and the coaxial cable 12
5 to the ground of protector 115 via the outer conductor. Since the ground resistance of the protector 115 is relatively small, it is easy to discharge through this path. That is, since the surge is easily induced in the casing of the communication device, the circuit element is frequently destroyed.
Therefore, various surge protection circuits have been conventionally devised. The configuration of the conventional surge protection circuit is shown in FIG.
It shows in (c). This is an example in which a communication line is connected to the right side of the communication device 150 and a power supply line is connected to the left side for simplification. Figure 6
(A) is an example in which a varistor 140, which is a lightning arrester, is inserted between both power supply lines. This aims at reducing the surge voltage generated between the power lines. Figure 6 (b)
Is an example in which a varistor 140 is provided between both lines of the power supply line and the ground. That is, this is an example in which the surge is bypassed to the ground. FIG. 6C is an example in which, for example, a plurality of PNPN lightning arresters 145 are further provided between both lines of the communication line, and the surge is bypassed to the ground there. It is a configuration that avoids surge intrusion from the communication line.

[0004]

However, as shown in FIG.
In the circuit shown in (a), the surge voltage generated between the power supply lines is reduced, but the surge between the power supply line and ground cannot be avoided.
This voltage fluctuation may cause dielectric breakdown of communication equipment. Further, FIGS. 6B and 6C show a configuration in which the invading surge is bypassed to the ground. However, it is difficult to take the configuration shown in FIGS. 6B and 6C because the communication device is often not grounded or cannot be grounded in a general home. Further, the ground of the CATV protector is generally grounded via a messenger wire used when pulling in the CATV transmission path. This messenger wire is stretched around the utility poles in the CATV transmission line, and when a messenger wire of these utility poles is struck by lightning, the ground potential of the protector in the vicinity rises and is pulled into the house. A lightning surge may enter through the coaxial cable, and a surge current may flow in the signal line through the power line of the power circuit in the cable modem. Due to these circumstances, a surge may be induced in the signal line in the communication device 150 or the signal line of the cable modem and the circuit may be destroyed. That is,
Neither method sufficiently avoids surge.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide an AC / DC converter which protects a DC-powered domestic device from surge.

[0006]

[Means, Actions and Effects for Solving the Problems] The invention according to claim 1 for solving the above problems is an AC / D for converting direct current into direct current power and supplying direct current power to home appliances.
In the C converter, a terminal connected to the external conductor of the CATV transmission line in the home device to which the CATV transmission line on the protector side is connected or a ground line connected to a part of the home device at the same potential as the external conductor And a surge absorbing member having one end connected to each of the two wires for inputting AC power and the other end connected to the ground wire, the AC / DC converter with surge protection function.

According to this structure, the surge intruding from each of the two lines of the AC power line flows through the surge absorbing member,
It flows through the ground wire, the outer conductor of the CATV transmission line on the protector side, and then to the ground of the protector. Therefore,
Since the surge does not flow in the DC-powered home equipment, the home equipment is not destroyed by the surge.
Even if a surge voltage occurs due to the grounding resistance when a surge flows through the grounding resistance of the protector, the two AC lines both have the same potential, so that no surge appears at the DC power supply terminal of the home device. In the above and below configurations,
The CATV transmission line also means a line in a house, and is generally a transmission line using a coaxial cable. Further, the home device may be any communication device or home electric device, and the home device for DC power supply and the home device for connecting the ground line may be different or the same.

The invention according to claim 2 is characterized in that another surge absorbing member for absorbing a surge is connected between two lines for inputting AC power. According to this configuration, the surge applied between the lines can be absorbed, and further protection against the surge can be enhanced.

According to a third aspect of the invention, in the invention according to the first or second aspect, the CATV on the protector side is provided.
The terminal to which the outer conductor of the CATV transmission line in the home device to which the transmission line is connected is connected is insulated from the housing of the home device. According to this structure, when a surge flows to the earth of the protector, a voltage is generated by the earth resistance of the earth. At this time, CATV
By insulating the terminal connected to the outer conductor of the CATV transmission line in the home device to which the transmission line is connected from the casing, it is possible to prevent damage due to this voltage, and to provide a more reliable surge countermeasure. .

According to a fourth aspect of the present invention, in the AC / DC converter for converting AC to DC and supplying DC power to a home device for inputting or outputting a signal to the CATV transmission line, the protector side is provided. The first CATV transmission line is connected
A terminal, a second terminal to which a CATV transmission line connected to a home device is connected, and a ground whose one end is connected to each line of two lines for inputting AC power and the other end is connected to an outer conductor of the first terminal And an AC / DC conversion circuit for converting AC power into DC power, superimposing the DC power on the central conductor of the second terminal and supplying the DC power to home equipment. AC / DC converter with surge protection function. According to this configuration, the surge that has entered from each of the two lines of the AC power line flows through the surge absorbing member, the ground, and is located at the protector side C connected to the first terminal.
It flows through the outer conductor of the ATV transmission line and flows to the earth of the protector. Therefore, since the surge does not flow to the DC-powered home device, the home device is not destroyed by the surge. Even if a surge voltage occurs due to the grounding resistance when a surge flows through the grounding resistance of the protector, the two AC lines both have the same potential, so that no surge appears at the DC power supply terminal of the home device.

The invention according to claim 5 is characterized in that, in the invention according to claim 4, another surge absorbing member for absorbing a surge is connected between two lines for inputting AC power. To do. According to this configuration, the surge applied between the lines can be absorbed, and further protection against the surge can be enhanced.

The invention according to claim 6 is the invention according to claim 4 or 5, wherein the outer conductors of the first terminal and the second terminal are insulated and separated. According to this configuration, when a surge flows to the earth of the protector, even if a voltage is generated by the earth resistance of the earth, the outer conductors of the first terminal and the second terminal are insulated and separated.
The voltage is not induced in the outer conductor of the terminal. Therefore, it is possible to reliably prevent the destruction of the home device connected to the second terminal due to the surge.

According to a seventh aspect of the present invention, in the invention according to any one of the fourth to sixth aspects, a signal line connecting the first terminal and the second terminal, and the outside of the first terminal are provided. A surge absorbing member is connected between members having the same electric potential as the conductor. According to this structure, the surge induced in the signal line of the CATV transmission line is transferred to the external conductor of the first terminal and the C on the protector side via the surge absorbing member.
It flows to the earth of the protector through the outer conductor of the ATV transmission line. Therefore, surge protection can be further enhanced.

According to an eighth aspect of the present invention, in the invention according to any one of the fourth to seventh aspects, the terminal to which the outer conductor of the CATV transmission line in the home device is connected is a casing of the home device. It is characterized by being insulated against the body. This structure aims at the same effect as the invention of claim 6. That is, similarly to the invention of claim 6, the voltage induced when a surge flows to the earth of the protector is prevented from being induced in the housing of the home device, and as a result, the surge is generated in the signal line of the home device. It can be surely prevented from being guided.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the examples below.

(First Embodiment) FIG. 1 shows a circuit configuration of an AC / DC converter 10 with a surge protection function of the present invention. AC1
AC power is input from the 00V AC power line 130.
Then, within the AC / DC converter 10, the alternating current 2
Lines 19a, 19b are provided. These two wires 19a and 19b are connected to the surge arrester 12 which is a surge absorbing member, respectively.
a, one end of the lightning arrester 12b is connected, and the other end thereof is connected to the ground line 20. The ground line 20 is the line terminal 3 of the cable modem 105, which is an example of a home device.
It is connected to the outer conductor of 0 by a clip 22. The CA on the protector side is connected to the line terminal 30 of the cable modem 105.
The coaxial cable 125, which is a TV transmission path, is connected, and the line terminal 30 is connected to the outdoor CAT via the protector 115.
It is connected to the V transmission line. In addition, two alternating current wires 19a, 19
A lightning arrester 13 is connected between the lines of b. As the surge arrester which is a surge absorbing member, for example, an arrester which is a kind of discharge tube in which argon gas, neon gas, etc. are enclosed,
Alternatively, a PNPN semiconductor element is used. Both of these are elements that conduct electricity at a voltage equal to or higher than a predetermined value.

The AC voltage supplied from the AC two-wire 19a, 19b is stepped down by the transformer 24, and the rectifier 23
Is rectified to direct current by. The DC power obtained by the rectifier 23 is supplied to the cable modem 10 via the DC power line 25.
5 to the DC power terminal 106.

This AC / DC converter 1 with surge protection function
0 is used as in FIG. 2 in a CATV data communication system, for example. That is, DC power is supplied to the wall surface unit 110 and the modem 105 such as a cable modem which is a home device. Here, the term wall unit 110 is used as a generic term for a serial unit, a commercial power outlet, and the like in a CATV system. In FIG.
The coaxial cable 125 from the wall unit 110 is connected to the line terminal 30 of the cable modem 105, and the DC power line 25 output from the AC / DC converter 10 is connected to the DC power terminal 106 of the cable modem 105.

Next, the surge protection function will be described with reference to FIGS. For example, when there is a lightning strike in the vicinity of this communication device, a surge occurs in the AC power line 130 and / or the CATV transmission line. In FIG. 1, this surge enters from the AC two wires 19 a and 19 b and / or the line terminal 30.
This surge is generated not only by direct lightning strike but also by guided lightning strike. For example, the surge generated between the AC two wires 19a and 19b is consumed by the lightning arrester 13. Further, the surge to the ground that has entered from the AC two wires 19a and 19b is consumed by the lightning arrester 12a and / or the lightning arrester 12b,
It flows to the ground through the ground wire 20, the outer conductor of the line terminal 30, the outer conductor of the coaxial cable 125, and the protector 115. At this time, the ground resistance of the CATV protector 115 is relatively small as compared with the ground resistance of the power supply ground in the home, and the surge has a large bypass effect on the ground of the protector.
As a result, no surge is induced in the DC power line 25, so there is no surge in the cable modem 105 and it is protected from surge.

However, if the earth resistance of the protector is large, the potential of the casing of the cable modem 105 fluctuates greatly. Therefore, the outer conductor of the line terminal 30 of the cable modem 105 is insulated and separated from the housing. For example, an insulation type R in which the line terminal 30 is insulated with a capacitor or the like.
By using the F terminal, it is possible to prevent the circuit breakdown due to the voltage rise due to the ground resistance of the protector. This allows
No surge is induced in the signal lines or elements inside the cable modem 105 and the computer device 100 due to fluctuations in the casing potential, so that surge protection can be achieved more reliably. As a method of insulating the line terminal 30 from the housing, the housing of the cable modem 105 may be an insulating resin housing.

Also, the CATV transmission line 125 on the protector side
With respect to surges that have entered from the outer conductor of, it operates as follows. This surge is transmitted through the outer conductor of the coaxial cable 125, the outer conductor of the line terminal 30, and the ground wire 20 to the arrester 12a and / or the arrester 12b and the AC 2
It flows to the ground through the line 19 (mainly the ground line of the two AC lines). As a result, the cable modem 105 and the computer device 100 are protected from the surge.

The line terminal 30 of the cable modem 105
When is an insulation type, there are the following effects. If the ground resistance of the ground wire of the power line is large, the potential of the ground wire 20 fluctuates greatly, but since the line terminal 30 is insulated from the housing, the housing of the communication equipment such as the cable modem 105 and the computer device 100. Body potential does not fluctuate. As a result, the element of the communication device is reliably prevented from being destroyed by the fluctuation of the casing potential.

In the above-mentioned embodiment, the most preferable embodiment is shown. However, the surge intruding from the AC power line can flow to the earth of the protector even if the line terminal 30 is not insulated and separated from the housing. Home appliances can be basically protected from surges. Further, although the surge absorbing member is provided between the two AC lines, the surge protection can be similarly achieved without this.

(Second Embodiment) FIG. 4 shows an example of another AC / DC converter 50 with a surge protection function. The parts having the same functions as those in the previous embodiment are designated by the same reference numerals. This A
The C / DC converter 50 is connected as shown in FIG.

In FIG. 4, the AC / DC converter 50 is
Case 11 as ground, lightning arrester 12a that is a surge absorbing member, lightning arrester 12b, lightning arrester 13, CA on the side of the protector
A line terminal 14 that connects the TV transmission line 125, a device terminal 15 that is a home device, such as a cable modem 105, a lightning arrester 17, a signal line 18, and an AC 2 line 19
a, 19b, a transformer 24, a rectifying circuit 23, and a choke coil 26. The device terminal 15 uses an insulation type RF terminal whose outer conductor is insulated from the housing 11 by a capacitor 16. Therefore, the outer conductor of the device terminal 15 and the outer conductor of the line terminal 14 are insulated and separated. Then, the DC power output from the rectifier circuit 23 is superimposed and output to the signal line 18 via the choke coil 26. The return line of the DC power is the outer conductor of the coaxial cable 126, and the outer conductor of the insulated device terminal 15 and the return line of the rectifier circuit 23 are connected.

The lightning arresters 12a, 12b, 13, 17
For example, an arrester which is a kind of discharge tube filled with argon gas or neon gas, or a PNPN semiconductor element is used. Both of these are elements that conduct electricity at a voltage equal to or higher than a predetermined value.

This AC / DC converter 50 is used as shown in FIG. 3 in a CATV data communication system.
That is, it is provided between the wall surface unit 110 and the modem 105 such as a cable modem which is a home device. That is, in FIG. 3, the coaxial cable 125 from the wall surface unit 110 is connected to the line terminal 14, and the modem 1 is connected to the device terminal 15.
A CATV transmission line (coaxial cable) 126 from 05 is connected. An AC power line 130 is connected to the AC 2 lines 19a and 19b.

At this time, the outer conductor of the line terminal 14 is directly connected to the housing 11 and grounded via the outer conductor of the coaxial cable 125 which is a CATV transmission line, the wall unit 110, and the protector 115. That is, the housing 11 is grounded. On the other hand, since the device terminal 15 uses an insulation type RF terminal, the external conductor is connected to the housing 11 via the capacitor 16. That is, the housings of the cable modem 105 and the computer device 100 are not grounded.

Next, the surge protection function will be described with reference to FIGS. For example, if there is a lightning strike near the home device, a surge occurs in the AC power line 130 and / or the CATV transmission line. This surge is AC 2 wire 1 in FIG.
It enters from 9a, 19b and / or the line end 14. This surge is generated not only by direct lightning strike but also by guided lightning strike. For example, the surge generated between the AC two wires 19a and 19b is consumed by the lightning arrester 13. Further, the surge to the ground that has entered through the AC two wires 19a and 19b is consumed by the lightning arrester 12a and / or the lightning arrester 12b.
1, the coaxial cable 125 and the protector 115 are used to bypass the ground. At this time, the ground resistance of the protector 115 of the CATV is compared with the ground resistance of the power supply ground in the home.
It is relatively small, and has a large bypass effect on surge protector grounding. As a result, the output of the rectifier circuit 23 and the housing 1
Cable modem 10
5 has no surge intrusion and is protected from surge.

If the earth resistance of the earth of the protector is large, the potential of the casing 11 fluctuates greatly. However, since the outer conductor of the device terminal 15 is insulated from the housing 11, the coaxial cable 1 connected to the cable modem 105 is
This voltage fluctuation is not induced in the outer conductor of 26. Thereby, the cable modem 105 and the computer device 1
Since the surge due to the potential fluctuation of the housing 11 is not induced to the signal line or the element inside 00, the surge protection can be more surely achieved.

Also, the CATV transmission line 125 on the protector side
With respect to surges that have entered from the outer conductor of, it operates as follows. This surge passes through the outer conductor of the coaxial cable 125, the outer conductor of the line terminal 14, and the housing 11 and / or the lightning arrester 12a and / or the lightning arrester 12b and the AC two-wire 19.
It flows to the ground via (mainly the ground wire of the two AC wires). As a result, the cable modem 105 and the computer device 100 are protected from the surge.

Further, since the equipment terminal 15 is of an insulation type, even if the ground resistance of the ground wire of the power line is large and the potential of the housing 11 fluctuates greatly, the housing of the communication equipment such as the cable modem 105 and the computer device 100. Body potential does not fluctuate. This surely prevents the elements of the communication device from being destroyed by the potential fluctuation of the housing 11.

In the above-mentioned embodiment, the most preferable embodiment is shown. However, even if the equipment terminal 15 is not insulated and separated from the housing 11, the surge that has entered from the AC power line can flow to the earth of the protector. , You can basically protect your home appliances from surges. Further, although the device terminal 15 is insulated from the housing 11, the line terminal 14 may be insulated from the housing. Furthermore, both the device terminal 15 and the line terminal 14 may be insulated. In short, the outer conductor of the device terminal 15 and the outer conductor of the line terminal 14 may be insulated and separated. Further, when the line terminal 14 is insulated from the housing 11, the housing 11 does not function as a ground, and therefore the outer conductor of the line terminal 14 and the lightning arresters 12a and 12a.
One end of b is connected to the outer conductor of the line terminal 14, and the housing 1
It is necessary to provide an insulated ground for 1. As a method of insulating the device terminal 15 and the line terminal 14, besides using a capacitor, the housing 11 itself may be an insulating resin housing. In the case of an insulating housing, as described above, the outer conductor of the line terminal 14 and the lightning arrester 12a are separately provided.
It is necessary to provide a ground for connecting one end of 12b. When an amplifier is inserted in the coaxial cable 125, wiring may be connected so that power is supplied from the rectifier circuit 23 to the amplifier. Further, although the surge absorbing member is provided between the two AC lines, the surge protection can be similarly achieved without this. Similarly, although the lightning arrester 17 is provided, it may be omitted. Further, since the AC / DC converter of the second embodiment is a system in which DC power is superimposed on the RF signal, it may be installed in the series unit installed on the wall surface.

[Brief description of drawings]

FIG. 1 A with surge protection function according to a first embodiment of the present invention
The circuit diagram showing the composition of a C / DC converter.

FIG. 2 A with surge protection function according to the first embodiment of the present invention
The block diagram which shows the CATV data communication system to which the C / DC converter is applied.

FIG. 3 A with surge protection function according to a second embodiment of the present invention
The block diagram which shows the CATV data communication system to which the C / DC converter is applied.

FIG. 4 A with surge protection function according to a second embodiment of the present invention
The circuit diagram showing the composition of a C / DC converter.

FIG. 5 is an explanatory diagram showing a surge intrusion route according to a conventional example.

FIG. 6 is a circuit diagram showing a conventional surge protection device.

[Explanation of symbols]

10 AC / DC Converter with Surge Protection Function 11 Case (also Ground) 12a, b Lightning Arrester (Specific Example of Surge Absorbing Member) 13 Lightning Arrester (Specific Example of Surge Absorbing Member) 14 Line Terminal 15 Device Terminal 16 Capacitor 17 Lightning Arrester (Specific Example of Surge Absorbing Member) 18 Signal Lines 19a, 19b AC 2 Line 20 Ground Line 22 Clip 23 Rectifier Circuit 25 DC Power Line 30 Line Terminal 100 Computer Device 105 Cable Modem (Specific Example of Home Appliance) 110 Wall Unit 115 Protector 125 CATV transmission line, coaxial cable 130 AC power line

Claims (8)

[Claims] 1. An AC / DC converter for converting alternating current into direct current and supplying direct current power to a home device, wherein an outer conductor of a CATV transmission line in a home device to which a CATV transmission line on a protector side is connected is connected. Surge with one end connected to the ground wire connected to a part of the household equipment at the same potential as the terminal or the external conductor and two wires for inputting AC power, and the other end connected to the ground wire An AC / DC converter with a surge protection function, which has an absorbing member. 2. The AC / surge protection function according to claim 1, wherein another surge absorbing member that absorbs a surge is connected between two lines for inputting the AC power.
DC converter. 3. A terminal to which the outer conductor of the CATV transmission line in the home device to which the CATV transmission line on the protector side is connected is insulated from the housing of the home device. The AC / DC converter with surge protection function according to claim 1 or 2. 4. A CATV transmission line on the protector side is connected to an in-home device for inputting or outputting a signal to and from a CATV transmission line, in an AC / DC converter for converting AC to DC and supplying DC power. A first terminal, a second terminal to which the CATV transmission line connected to the home device is connected, and one end connected to each of two lines for inputting AC power, the other end being an outer conductor of the first terminal And a surge absorbing member connected to the ground, which converts AC power into DC power, and converts the DC power into the second power
AC to be superposed on the central conductor of the terminal and supplied to the household equipment
AC / DC converter with surge protection function, comprising: a DC / DC conversion circuit. 5. The AC / surge protection function according to claim 4, wherein another surge absorbing member that absorbs a surge is connected between the two wires for inputting the AC power.
DC converter. 6. The AC / DC converter with surge protection function according to claim 4, wherein the outer conductors of the first terminal and the second terminal are insulated and separated. 7. A surge absorbing member is connected between a signal line connecting the first terminal and the second terminal and a member having the same electric potential as the outer conductor of the first terminal. The AC / DC converter with surge protection function according to any one of claims 4 to 6. 8. The terminal to which the outer conductor of the CATV transmission line in the home device is connected is insulated from the housing of the home device.
An AC / DC converter with surge protection function according to any one of 1.