JPH1145802A - Communication circuit protecting resistor and communication circuit protector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the concentration of electric field and generation of sparks by a method, wherein a meandering resistor is formed on an insulating substrate, and a resistor of resistirity lower. than that of an electrode or the meandering resistor is formed, so as to be overlapped on each other in at least an inside portion of a bending part of the meandering resistor. SOLUTION: A communication circuit protecting resistor 1 comprises an alumina substrate 2 which is an insulating substrate, a meandering resistor 3 formed by thick film printing on the almina substrate 2, and an approximately semicircular electrode 4 similarly formed by a thick film printing on an upper portion inside a bending part of the meandering resistor 3. The resistivity of an electrode 4 (for example, 0.00001 ω.cm) which is sufficiently lower than the of the meandering resistivity 3 (for example, 0.001 3Ω.-cm) is used. As a result, the resistivity inside the bending part is lower than that of a linear portion, and even when an overcorrect due to a thunder surge, etc. flows, the concentration of an electric field on the portion inside the bending portion is suppressed and possibility of the spark or breaking of the meandering resistor 3 is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication line protection resistor and a communication line protection device, and more particularly to a communication line for protecting a communication device such as an exchange from an abnormal current flowing from the communication cable due to contact between the communication cable and a power line. The present invention relates to a line protection device and a communication line protection resistor used therein.

[0002]

2. Description of the Related Art FIG. 5 shows an equivalent circuit of a communication line protection device. In FIG. 5, a communication line protection device 40 is configured by connecting communication line protection resistors 41a and 41b and positive temperature coefficient thermistors 42a and 42b in series, respectively, and has one end connected to communication line side input terminals 43a and 43b.
The other end is the protected device side output terminals 44a and 44
b, and each is configured as two communication line protection circuits. The two communication line protection circuits have no electrical connection to each other.

FIG. 6 shows a communication line protection device 40 shown in FIG.
1 shows a configuration of a conventional communication line protection resistor used in the present invention. In FIG. 6, the communication line protection resistor 41a includes an alumina substrate 45 which is an insulating substrate and a meandering resistor 46 formed on the alumina substrate 45 by thick film printing. The configuration of the communication line protection resistor 41b is also substantially the same, and a description thereof will be omitted here.

Here, returning to FIG. 5, the communication line protection device 4
The operation of 0 will be described. Generally a positive temperature coefficient thermistor 4
The impedance of the 2a and 42b at room temperature varies. However, if the impedances of the two communication line protection circuits of the communication line protection device 40 vary, the characteristics of the communication line are adversely affected. Accordingly, the communication line protection resistors 41a and 41b set to appropriate values are connected in series to the positive characteristic thermistors 42a and 42b, respectively, so that the impedances of the two communication line protection circuits are substantially equal.

[0005] The communication line protection device 4 configured as described above.
0, an abnormal current flows from the communication cable to the communication line protection device 40 due to contact between the communication cable and the power line.
The positive current thermistor 4
2a and 42b generate heat, and the heat causes the resistance values of the positive temperature coefficient thermistors 42a and 42b to rise sharply, thereby reducing the flowing current. In this way, it is possible to prevent the communication device from being destroyed due to an abnormal current flowing.

[0006]

In such a communication line protection device 40 as well, the positive temperature coefficient thermistors 42a and 42b are protected against an instantaneous overcurrent due to a lightning surge or the like.
Since it works only as a resistor, devices such as lightning surge absorbing diodes and varistors are provided on the communication equipment side.

However, in the above-mentioned communication line protection resistors 41a and 41b, when a high voltage overcurrent such as a lightning surge flows, if the radius of the bent portion of the meandering resistor 46 is small, the inside of the bent portion becomes inward. The electric field concentrates on the portion, and a spark is generated in this portion, and there is a possibility that the meandering resistor 46 is broken. In order to avoid this, a measure is taken to increase the radius of the bent portion of the meandering resistor 46 to make the current flowing inside and outside the bent portion as uniform as possible. There is a problem that the space between the adjacent linear portions 46 is widened and the entire area is increased, which hinders downsizing of the communication line protection resistor 41.

On the other hand, Japanese Utility Model Application Laid-Open No. 56-172901
In the publication, a configuration of a resistor shown in FIG. 7 is proposed. In FIG. 7, the resistor 50 is composed of an alumina substrate 51 which is an insulating substrate, a plurality of linear resistors 52 formed on the alumina substrate 51 in parallel with each other, and a linear resistor 52 adjacent to both ends thereof. Linear resistor 5
It is composed of a plurality of rectangular connection electrodes 53 connected to the second connection electrode 2 and serves as a meandering resistor as a whole.

By configuring the resistor 50 in this manner, the resistor 50 has no bent portion, and the connection electrode 53 corresponding to the bent portion of the meandering resistor has low resistance.
The concentration of the electric field there is reduced. However, on the contrary, since the end of the resistor 52 is formed in a square shape and the connection electrode 53 is formed in a rectangular shape, an electric field is concentrated on the corner, and there is a problem that discharge is easily caused therefrom. . Further, for example, in a portion where the connection electrode 53 is formed on the two linear resistors 52, the resistance R0 of the linear resistor 52 and the resistance R of the connection electrode 53 are equivalent as shown in FIG.
1 are alternately connected in series. However, since a large electric field is applied to the connection between the linear resistor 52 and the connection electrode 53, which are conductors having greatly different resistivity, a discharge is also generated at this connection. There is also a problem that the occurrence of the problem easily occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, and it is difficult to concentrate an electric field, and it is difficult to discharge, and a downsized communication line protection resistor, and a communication line using the same. Provide a protective device.

[0011]

In order to achieve the above object, a communication line protection resistor according to the present invention comprises a meandering resistor formed on an insulating substrate and at least a bent portion of the meandering resistor. An electrode or a resistor having a lower resistivity than the meandering resistor is formed on the inner portion.

Further, the communication line protection device according to the present invention is characterized in that it comprises two communication line protection circuits each having a positive characteristic thermistor connected in series to the communication line protection resistor according to the first aspect. I do.

With this configuration, the communication line protection resistor according to the present invention is less likely to cause the concentration of the electric field at the bent portion of the meandering resistor, the resulting discharge, and the breakage of the meandering resistor. The size can be reduced by reducing the radius of the bent portion. Further, the communication line protection device of the present invention can be downsized.

[0014]

FIG. 1 shows an embodiment of a communication line protection resistor according to the present invention. In FIG. 1, a communication line protection resistor 1 includes an alumina substrate 2 which is an insulating substrate, a meandering resistor 3 formed on the alumina substrate 2 by thick film printing, and an upper portion inside the bent portion of the meandering resistor 3. And a substantially semicircular electrode 4 also formed by thick film printing.
The resistivity of the electrode 4 (for example, 0.00001 Ω · cm) is sufficiently lower than the resistivity of the meandering resistor 3 (for example, 0.001 Ω · cm). The equivalent circuit of the communication line protection device equipped with the communication line protection resistor 1 is the same as that of the conventional example shown in FIG. 5, and the description is omitted here.

In the communication line protection resistor 1 configured as described above, since the electrode 4 is formed on the upper side inside the bent portion of the meandering resistor 3, the resistivity inside the bent portion is linear. Even when an overcurrent flows due to a lightning surge or the like, the concentration of the electric field on the inside of the bent portion is suppressed, and the possibility of the spark and the meandering resistor 3 being destroyed is reduced as compared with the conventional example. . Further, since the bent portion of the meandering resistor 3 and the electrode 4 are formed in a substantially semicircular shape, there is no corner where the electric field concentrates, and there is little possibility that the electric field concentrates there and discharge occurs. Further, in the bent portion of the meandering resistor 3, as shown in the equivalent circuit of FIG. 2, of the circuit in which the resistors R0, R2, and R0 of the meandering resistor 3 are connected in series, Since the resistance R3 of the electrode 4 is added in parallel with the resistance R2 in a distributed manner, there is no portion where a large electric field concentrates and is applied between the meandering resistor 3 and the electrode 4. The possibility of discharge at the connection is also reduced. As a result, the radius of the bent portion can be reduced, the distance between the adjacent linear portions of the meandering resistor 3 is reduced, and the communication line protection resistor 1 is reduced.
Can be reduced in overall area.

FIG. 3 shows another embodiment of the communication line protection resistor of the present invention. In FIG. 3, a communication line protection resistor 10 includes an alumina substrate 11, a meandering resistor 12 formed on the alumina substrate 11 by thick film printing, and a thick film printing on the bent portion of the meandering resistor 12. It is composed of a resistor 13 formed in substantially the same shape as the bent portion.
The resistivity of the resistor 13 is set lower than the resistivity of the meandering resistor 11.

By configuring the communication line protection resistor 10 in this manner, the resistance of the bent portion of the meandering resistor 12 is reduced, and even if an overcurrent due to lightning surge or the like flows,
Concentration of the electric field on the inner portion of the bent portion is suppressed, and the possibility of sparks and breakage of the meandering resistor 12 is reduced as compared with the conventional example. In addition, since the bent portion is formed in an arc shape including the resistor 13, there is no corner where the electric field concentrates, and there is little possibility that the electric field concentrates there and discharge occurs. As a result, the radius of the bent portion can be reduced,
The distance between the adjacent linear portions of the meandering resistor 12 can be reduced, and the overall area of the communication line protection resistor can be reduced.

In the above embodiment, the electrodes 4 and the resistors 13 are formed above the bent portions of the meandering resistors 3 and 12, but they are formed beforehand below the bent portions. Is also good. Although the alumina substrate is used as the insulating substrate, it may be another substrate such as a ceramic or resin.

FIG. 4 shows an embodiment of the communication line protection device of the present invention. In FIG. 4, the communication line protection device 20 includes:
Alumina substrate 21 as an insulating substrate, and alumina substrate 21
Meandering resistors 22a and 22b formed on the meandering resistors 22a and 22b, substantially semicircular electrodes 23a and 23b also formed on the inner side of the bent portions of the meandering resistors 22a and 22b by the thick-film printing, positive characteristics Thermistor 24
a and 24b, wiring electrodes 25a, 25b, 26a, 2
6b, 27a and 27b, one terminal of positive temperature coefficient thermistors 24a and 24b and wiring electrodes 26a and 26b
Are connected to each other, the communication line side input terminals 29a and 29b, and the protected device side output terminals 30a and 30b. Here, the electrode 23
a and 23b have meandering resistors 22a and 22b.
2b is sufficiently lower than the resistivity. The communication line side input terminal 29a includes a wiring electrode 27a, a meandering resistor 22a, a wiring electrode 25a, a positive temperature coefficient thermistor 24a,
It is connected to the protected device side output terminal 30a via the metal piece 28a and the wiring electrode 26a in order to form one communication line protection circuit. Similarly, the communication line side input terminal 29
b is connected to the protected device side output terminal 30b via the wiring electrode 27b, the meandering resistor 22b, the wiring electrode 25b, the positive temperature coefficient thermistor 24b, the metal piece 28b, and the wiring electrode 26b in this order, and another communication line. It constitutes a protection circuit.

The communication line protection device 2 thus configured
At 0, the equivalent circuit is the same as that of the conventional example shown in FIG. 5 and its description is omitted, but the communication line protection resistors of the respective communication line protection circuits are the same as those of the embodiment shown in FIG. Thus, the effect of reducing the area of the communication line protection resistor similar to the embodiment of FIG. 1 can be obtained, and as a result, the communication line protection device 20 itself can be reduced in size.

In the communication line protection circuit 20,
Although the same configuration as the communication line protection resistor 1 shown in the embodiment of FIG. 1 is used, the same configuration as the communication line protection resistor 10 shown in the embodiment of FIG. 3 may be used.

[0022]

According to the resistor for protecting a communication line of the present invention, a meandering resistor is formed on an insulating substrate, and an electrode or a meandering resistor is provided on at least an inner portion of the bent portion of the meandering resistor. A resistor having a lower resistivity than that of the other is formed.

As a result, the resistivity inside the bent portion of the meandering resistor is reduced, and even when an overcurrent due to lightning surge or the like flows, the concentration of the electric field inside the bent portion is suppressed. The possibility of spark generation and breakage of the meandering resistor is reduced. In addition, since the bent portion and the electrode and resistor formed on top of it are formed in a substantially semicircular or arc shape, there is no corner where the electric field concentrates, and there is a possibility that the electric field concentrates there and discharge occurs Also less. Further, since the electrode formed on the bent portion has a shape in which a low-resistance resistor is added in parallel with the resistance of the bent portion of the meandering resistor and distributed, the meandering resistor and the electrode A large electric field does not concentrate on the connection part, and the possibility of discharge at the connection part is small. As a result, the radius of the bent portion can be reduced, the interval between the linear portions adjacent to each other in the meandering resistor is reduced, and the entire area of the communication line protection resistor, and thus the communication line protection device, is reduced. Can be.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the configuration of a communication line protection resistor of the present invention.

FIG. 2 is an equivalent circuit diagram before and after a bent portion in the embodiment of FIG. 1;

FIG. 3 is a diagram showing another embodiment of the configuration of the communication line protection resistor of the present invention.

FIG. 4 is a diagram showing one embodiment of the configuration of the communication line protection device of the present invention.

FIG. 5 is an equivalent circuit diagram of the communication line protection device.

FIG. 6 is a diagram showing a configuration of a conventional communication line protection resistor.

FIG. 7 is a diagram showing another example of the configuration of a conventional communication line protection resistor.

8 is an equivalent circuit diagram before and after a connection electrode portion in the embodiment of FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Communication line protection resistor 2 ... Alumina substrate 3 ... Meandering resistor 4 ... Electrode

Claims (2)

[Claims] 1. A meandering resistor is formed on an insulating substrate, and an electrode or a resistor having a lower resistivity than the meandering resistor is formed on at least an inner portion of a bent portion of the meandering resistor. A resistor for protecting a communication line. 2. A communication line protection device comprising two communication line protection circuits each comprising a positive temperature coefficient thermistor connected in series to the communication line protection resistor according to claim 1.