JPH02100592A - Dial pulse sending circuit - Google Patents

Abstract

PURPOSE:To obviate an induction coil, and to miniaturize a dial pulse sending circuit, and to reduce the distortion of a dial pulse by constituting DC loops during sending the dial pulse and during a talk of a transistor(TR), a resistor and a capacitor as the main constituents. CONSTITUTION:At the time of the talk, since a first switch 11 is turned ON, a base current IB is supplied to the TR 13 through the resistor 15. Thus, the TR 13 is turned ON, and a loop current IL flows in a subscribers line 1. On the other hand, a second switch 12 during the talk is ON, and even when a voice signal is superposed on the subscriber's line 1, an AC current to flow in the resistor 15 is bypassed through the second switch and the capacitor 16. Therefore, an interval between the collector and the emitter of the TR 13 becomes of high impedance for the voice signal. Besides, while the dial pulse is sent, since the second switch is OFF, and the capacitor 15 is opened, the dial pulse free from the distortion can be sent.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a dial pulse sending circuit for sending a loop dial signal from a universal repeater to an exchange, and aims to miniaturize the device and send dial pulses without distortion. is connected to the subscriber line, and is ON from activation to disconnection except when a break pulse is being sent when a call is made, and is ON from response to termination when a call is received, and the first switch is turned ON to OFF. a second swing which is turned OFF or ON at the time of transition and continues to maintain the state while dial pulses are continuously sent; one end is connected to the subscriber line, and the other end is connected to the other end of the first swing. connected, has a built-in audio signal bypass path, and turns on the second switch.
, and transistor circuit means for forming a DC loop during a call and during dial pulse transmission in accordance with the OFF state.

[Industrial application field]

The present invention relates to a dial pulse sending circuit for sending a loop dial signal from a universal repeater to an automatic switchboard at an interface between the universal repeater and the automatic switchboard.

[Prior art] A dial pulse sending circuit sends a dial pulse to the exchange by ON10 F F of a DC loop, and has a high impedance to audio frequency signals while maintaining the DC loop during a call. .

FIG. 8 is a block diagram of a conventional dial pulse sending circuit.

In the figure, a subscriber line 1 includes a loop monitoring section 2 of an exchange.
is connected, and the loop monitoring section 2 is composed of a relay 3 and a battery 4.

5 is a dial pulse sending circuit;
It is provided with a spin chia and a guide wire 8, one end of a primary coil 8a and a secondary coil 8b of the guide wire 8 are connected to the subscriber line 1, and the other ends are directly connected to each other. Further, a first switch 6 is connected between one end of the primary coil 8a and the subscriber line 1, and a second switch 7 connects the primary and secondary coils 8a,
8b is connected in parallel between one end of the terminal.

In the conventional dial pulse sending circuit configured as described above, when the dial pulse is being sent, the second switch 7
is turned on to short-circuit the guide ring 8, and the first switch 6 is opened for the number of pulses, thereby sending a loop dial signal to the exchange. At this time, the guide wire 8 is
The short-circuiting by switch 7 improves the distortion of the dial pulse due to the influence of the guide wire.

Also, during a call, the first switch 6 is held ON and the second
The switch 7 is turned OFF and the guide wire 8 is placed in series within the DC loop, thereby creating a high impedance for audio frequency signals.

(Problem to be solved by the invention) In the conventional dial pulse sending circuit as described above,
In order to ensure that the magnetism does not saturate even with a communication current of several tens of milliamperes and to provide a sufficiently high impedance for audio frequency signals, a high-inductance induction wire is required, and accordingly, the induction wire ring is There was a problem in that the size of the universal repeater became large, making it impossible to downsize the universal repeater.

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a dial pulse sending circuit that is downsized and capable of sending out dial pulses without distortion.

[Means to solve the problem]

FIG. 1 is a diagram showing the principle of the dial pulse sending circuit of the present invention.

In the figure, a first switch 11 connected to subscriber line 1
is ON from startup to disconnection except when a break pulse is being sent during a call, and remains ON from response to termination when a call is received.

The second switch 12 changes from the ON state of the first switch 11 to OFF state.
It turns OFF or ON when it moves to F, and continues to maintain this state while dial pulses are continuously sent.

The transistor circuit means 13A has one end connected to the subscriber line 1,
The other end is connected to the other end of the first switch 11, has an audio signal bypass path, and forms a DC loop during a call and during dial pulse transmission according to ON and OFF of the second switch. It is.

[Function] During a call, the first switch and the second switch are turned on, and by turning the second switch ON or OFF, a DC loop is formed in which the transistor circuit means is talking, and the transistor circuit responds to the voice signal with high voltage. It becomes impedance. Then, the dial pulses are sent out by turning off the first switch 11 by the number of pulses. While dial pulses are being sent, the transistor circuit is kept at low impedance by turning the second switch ON or OFF.

Therefore, the present invention eliminates the need for a guide wire, making it possible to downsize the dial pulse sending circuit.

〔Example〕

Hereinafter, the present invention will be explained in detail based on the drawings.

Fig. 2 shows the first diagram of the dial pulse sending circuit according to the present invention.
This is an example.

In the figure, the loop monitoring section 2 of the exchange is comprised of a relay 3 and a battery 4 connected between the subscriber line 1 and the ground, as in the prior art.

The dial pulse sending circuit 10 includes a first switch '11.
Second switch 12. Transistor 13 and resistor 14.1
5 and a capacitor 16, one end of the first switch 11 is connected to one end of the subscriber line 1, and the collector of the transistor 13 is connected to the other side of the subscriber line 1. is connected to the other end of the first switch 11, and a resistor 14 is directly connected to the emitter of the transistor 13. In addition, the transistor 13
A resistor 15 is connected between the base and collector of the transistor 13, and a second switch 12 is connected between the connection point between the other end of the first switch 11 and the emitter resistor 15 and the base of the transistor 13.
A series circuit of the capacitor 16 and the capacitor 16 are connected in parallel.

In the dial pulse sending circuit of this embodiment configured as described above, the first switch 11 is ON from the time of startup to the time of disconnection during the sending of a break pulse at the time of making a call, and from the time of answering to the time of receiving a call. It remains ON until the end of the conversation. Further, the second switch 12 is configured so that the first switch 11 is turned off.
It turns OFF when it changes from N to OFF, and operates to maintain the OFF state while the dial pulse continues. Therefore, during a call, the first switch 11 is turned on, and base current 8 is supplied to the transistor 13 through the resistor 15, which turns the transistor 13 on.
However, in the subscriber line 1, a loop current IL of IL-18mohFE'II+ flows.

However, hFE is the DC current amplification factor of the transistor 13.

On the other hand, since the second switch 12 is ON during a call, even if a voice signal is superimposed on the subscriber line 1, the alternating current flowing through the resistor 15 is bypassed through the second switch and the capacitor 16. Therefore, the collector of transistor 13
There is a high impedance between the emitters for audio signals.

Furthermore, the dial pulses are sent by turning off the first switch 11 by the number of pulses. At this time,
If the second switch 12 is turned on, when the first switch 11 returns from OFF to ON, the rise of the loop current (2) will be delayed due to charging of the capacitor 15, and the dial pulse will be significantly distorted. In this case, the second switch 12 is OFF while the dial pulse is being sent out, and the capacitor 15 is open, so it is possible to send out the dial pulse without distortion.

In this embodiment as described above, a dial pulse sending circuit can be realized without requiring a guide wire, and miniaturization is possible.

” So [W Figure 3 shows the second dial pulse sending circuit according to the present invention.
FIG.

In the figure, parts that are the same as those in FIG. 2 are denoted by the same reference numerals, and their explanation will be omitted, and the parts that are different from those in FIG. 2 will be mainly described.

That is, as is clear from the figure, a constant voltage diode 17 is connected in parallel to a series circuit of a second switch 12 and a capacitor 16.

In this way, by making the base bias of the transistor 13 a constant voltage by the constant voltage diode 17, the base current of the transistor 13 is limited, and the transistor 13
This makes it possible to prevent an unnecessary increase in the loop current flowing through the transistor and suppress heat generation in the transistor.

Figure 4 shows the third dial pulse output path according to the present invention.
FIG.

In the figure, parts that are the same as those in FIG. 2 are denoted by the same reference numerals, and their explanation will be omitted, and the parts that are different from those in FIG. 1 will be described with emphasis.

This embodiment differs from the others in that only a capacitor 16 is connected between the base of the transistor 13 and one end of a resistor 14 connected to its emitter, and the second switch 12 is
It is connected in parallel to the resistor 15 connected between the collector and emitter of the transistor 13.

In the third embodiment configured as described above, during a call, the first switch 11 is turned ON and the second switch 12 is turned OFF.
In order to become an FF, the base current ■ is supplied to the transistor 11 through the resistor 15, and accordingly, the transistor 1
3 is turned ON, and IL=Ia+hyt・1.
A loop current ■ flows. Also, at this time, even if an audio signal is superimposed on the subscriber line 1, the alternating current is bypassed by the capacitor 16, so that the collector-emitter of the transistor 13 has a high impedance with respect to the audio signal.

The dial pulses are sent by turning off the first switch by the number of pulses. At this time, the second switch 12 is ON when the first switch 11 is turned OFF, so when the first switch 11 returns from OFF to ON, the loop current flowing through the subscriber line 1 is transferred to the second switch 12. When the capacitor 16 is charged up, the transistor 13 is turned on, and the loop current flows through the transistor 13. That is, the delay in response of the transistor 13 caused by the capacitor 16 is compensated for by the charging current flowing through the capacitor 16, so that it is possible to send dial pulses without distortion.

FIG. 5 shows the fourth dial pulse sending circuit according to the present invention.
FIG.

In the figure, parts that are the same as those in FIG. 4 are denoted by the same reference numerals, and their explanation will be omitted, and points different from those in FIG. 4 will be emphasized.

That is, as is clear from the figure, a constant voltage diode 18 is connected in parallel to the capacitor 16.

In such an embodiment, the constant voltage diode 18 limits the base current of the transistor 13, prevents an unnecessary increase in the loop current during a call, and has the effect of suppressing heat generation of the transistor 13.

Figure 6 shows the fifth part of the dial pulse sending circuit according to the present invention.
FIG.

In the figure, parts that are the same as those in FIG. 4 are denoted by the same reference numerals, and their explanation will be omitted, and points different from those in FIG. 4 will be emphasized.

That is, a diode 19 is connected between the base and emitter of the transistor 130, and the second switch 12 is connected to the transistor 1.
3 are connected in parallel between the collector and emitter.

In the dial pulse sending circuit configured as described above, during a call, the first switch 11 is ON and the second switch 12 is OFF.
Since the base current 8 is supplied to the transistor 13 through the resistor 15, the transistor 13 becomes conductive, thereby forming a DC loop, and the subscriber line receives IL = Is + hrE-Im. Loop current flows.

At this time, even if an audio signal is superimposed on the subscriber line, the alternating current is bypassed through the capacitor 16, so that the collector-emitter of the transistor 13 has a high impedance with respect to the audio signal.

Furthermore, the dial pulses are sent by turning off the first switch 11 by the number of pulses. At this time,
Since the second switch 12 is ON when the first switch is turned OFF, when the first switch 11 returns from OFF to ON, the loop current flowing through the subscriber line 1 is changed to the second switch 12.
It flows through switch 12, which allows for the delivery of undistorted dial pulses.

Furthermore, by connecting the diode 19 with the polarity shown in FIG. 6, both the first switch 11 and the second switch 12 are turned off.
When N, the capacitor 16 is charged, which turns off the second switch 12 at the end of dial pulse transmission.
Therefore, it is possible to prevent the generation of pseudo pulses due to a temporary OFF operation when the path of the loop current shifts from the second switch 12 side to the transistor 13 side.

7 shows the sixth part of the dial pulse sending circuit according to the present invention.
FIG.

In the figure, the same parts as in FIG. 6 are given the same reference numerals, and the explanation thereof will be omitted, and different parts will be mainly described.

That is, in this embodiment, a constant voltage diode 20 is connected in parallel to the capacitor 16, thereby limiting the pace current when the loop current flows through the transistor 13.

In this way, an unnecessary increase in the loop current can be prevented and heat generation of the transistor 13 can be suppressed.

In each of the embodiments described above, the first switch 11 and the second switch 12 are constructed from a mechanical switch such as a relay, an electronic switch using a photocoupler, or the like.

〔Effect of the invention〕

As described above, according to the present invention, since the DC loop during dial pulse transmission and during a call is mainly composed of transistors, resistors, and capacitors, the guide wire is not required, and accordingly, the dial This has the advantage that the pulse sending circuit can be downsized and distortion of dial pulses can be eliminated.

[Brief explanation of drawings]

FIG. 1 is a principle diagram of a dial pulse sending circuit according to the present invention, FIG. 2 is a block diagram showing a first embodiment of a dial pulse sending circuit according to the present invention, and FIG. 3 is a diagram showing a first embodiment of a dial pulse sending circuit according to the present invention. FIG. 4 is a block diagram showing a third embodiment of the dial pulse sending circuit according to the present invention; FIG. 5 is a block diagram showing a fourth embodiment of the dial pulse sending circuit according to the present invention. 6 is a block diagram showing a fifth embodiment of a dial pulse sending circuit according to the present invention; FIG. 7 is a block diagram showing a sixth embodiment of a dial pulse sending circuit according to the present invention; FIG. 1 is a configuration diagram of a conventional dial pulse sending circuit. 2 is a second switch, 3 is a transistor, 3A is a transistor circuit means, 4.15 is a resistor, 6 is a capacitor, 7.18.20 is a constant voltage diode, and 9 is a diode. In the figure, 1 is a subscriber line, 2 is a loop monitoring section, 10 is a dial pulse sending circuit, 11 is a first switch, "-1"

Claims (1)

[Claims] (1) One end is connected to the subscriber line (1), and the first switch (1
1), and a second switch (11) that is turned OFF or ON when the first switch (11) changes from ON to OFF and continues to maintain the state while dial pulses are continuously sent out.
2), one end is connected to the subscriber line (1) and the other end is connected to the first switch (1).
1) It is connected to the other end, has a built-in audio signal bypass path, and is used to turn on and off the second switch (12).
A dial pulse sending circuit comprising: transistor circuit means (13) for forming a DC loop during a call and during dial pulse sending according to the above.