JPS61145947A - Ring trip circuit - Google Patents

Abstract

PURPOSE:To promote miniaturizing and economical effects of a digital exchange by providing a means that generates a different DC voltage when a called telephone made a reply in plural subscribers' circuits and making ring trip operation for plural subscriber's circuits in common by discriminating the DC voltage. CONSTITUTION:A constant voltage diode 20 is provided in a call signal supply route as a device to generate a different DC voltage when a called telephone made a reply, and comparators 171, 172 and a gate 26 are provided in a ring trip circuit provided in common in subscribers' circuits 01, 02 as a means for discriminating DC voltage generated in each subscriber's circuit. The comparator 171 outputs a reset signal when a telephone set 11 changed from on-hook state to off-hook state, and the comparator 172 outputs a reset signal when either of telephone sets 11, 12 changed from on-hook state to off-hook state. By the ring trip circuit provided in common, it becomes possible to send out or stop a call signal when either of telephone sets 11 or 12 changed from on-hook state to off-hook state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of a ring trip circuit in a subscriber circuit for a digital exchange.

In digital exchanges, high-power signals such as paging signals cannot be transmitted via the communication channel network, so a paging signal sending function is provided in the subscriber circuit, and a paging signal is sent when the called subscriber answers. A ring trip circuit for stopping transmission is also provided in the subscriber circuit.

Note that since the number of subscriber circuits is equal to the number of subscribers that can be accommodated in a digital exchange, there is a strong demand for miniaturization and economicalization of subscriber circuits in order to make the digital exchange more compact and economical.

[Conventional technology]

FIG. 2 is a diagram showing an example of a conventional ring trip circuit in this type of subscriber circuit.

In FIG. 2, when a call arrives at a telephone 1 accommodated via a subscriber line, an SD signal is sent from a control section (not shown) to set a flip-flop 2 and drive an RT relay 3.

As a result, for example, 2.0 Hz/100 pol) (rms
) from a ringing signal source 4 which generates a ringing signal, a resistor 5.6
, rt contact 7, subscriber line (B line), telephone 1, subscriber *
(A line), a ringing signal is sent via the rt contact 8 and the resistor 9, causing the telephone l to ring a bell.

Both ends of resistor 5 are connected to a non-inverting input terminal (+) and an inverting input terminal (-) of operational amplifier 12 via resistors 10 and 11, respectively. The operational amplifier 12 has a resistor 13 and a capacitor 1 connected to a non-inverting input terminal (+).
4, and a resistor 15 and capacitor 16 connected between the inverting input terminal (-) and the output terminal, forming a differential integration circuit.

The voltages across the total resistance 5 are respectively ■ and VzzR@
. = R11, R+5 = Rt Ct 4 = C (where R is the resistance value of resistor i, and C5 is the capacitance value of capacitor j), and the impedance of the parallel circuit of resistor 13 and capacitor 14 is zI. Then, the output voltage V of the operational amplifier 12 is expressed by equation (1).

Vs = Z+ (Vt Vg)/R+++VA
- (1) When the telephone 1 is in an unanswered state, that is, in an on-hook state, a series circuit (impedance of approximately 10 kilohms) of a bell winding and a capacitor is formed in the telephone equipment, so no direct current flows, and approximately A ringing signal current of about 10 milliamps flows.

Furthermore, since up to three telephone sets 1 can be connected to one subscriber line, the maximum value of the ringing signal current flowing through the resistor 5 is approximately 3.
It becomes 0 milliampere. Furthermore, R,=250 ohm, R1
= 750 ohms, R9 = 200 ohms, RItr =
Assuming that R+ + = RI 3 = Rrs = 100 kilohms and Cl4 = CI & = 4 microfarads, the output voltage V3m of the operational amplifier 12 is expressed by equation (2).

V 3vh #0.21 +V a
...(2) On the other hand, when the telephone 1 responds, that is, when it enters the off-footer state, a DC circuit of about 150 ohms is formed in the telephone 1, and the DC current is superimposed on the ringing signal to the DC power source Vm (=48 volts). Sent from

In such a case, the output voltage V, of the operational amplifier 12 will be the maximum value V,Ib (formula (3)) when the subscriber line resistance is 0 and the DC power supply V is 153 volts, and the subscriber line resistance will be the maximum value (
For example, 1900 ohms), when the DC power supply V is -43 volts, the minimum value V, Ic (formula (4)) is obtained.

Vsb=10(oct+0.52(oct+Va
...(3) V3c=3.5 (Be)
+0.23 tac) + VA (4) The output voltage v3 of the operational amplifier 12 is input to the non-inverting input terminal (+) of the comparator 17, and the inverting input terminal (-) of the comparator 17 is connected to the resistor. The threshold voltage V, created by 18 and 19 is input.

The comparator 12 compares the output voltage ■, which is input to the non-inverting input terminal (+), and the threshold voltage v, which is input to the inverting input terminal (-), and determines whether the condition V3<V is satisfied. If the condition V<■3 is satisfied without outputting the rising cent signal, outputting the reset signal and resetting the flip-flop 2,
The RT relay 3 is restored and the sending of the calling signal is stopped.

Therefore, the dark value voltage ■, is converted to the output voltage V3. If it is set to an intermediate value between a and V3c (for example, 1.97+VA), it becomes possible to detect that the telephone 1 changes from the on-footer state to the off-footer state and stop sending out the ringing signal.

[Problem that the invention seeks to solve]

As is clear from the above description, conventional ring trip circuits are provided in each subscriber circuit. This has resulted in hindering miniaturization and economicalization of each subscriber circuit.

[Means for solving problems]

The problem is that in a subscriber circuit for a digital exchange, a plurality of subscriber circuits are provided with means for generating different DC voltages when a calling telephone answers, and each of the DC voltages generated in each subscriber circuit is The solution is to perform a common ring trip operation on the plurality of subscriber circuits by identifying the voltage.

[Operation] That is, according to the present invention, since the ring trip circuit is provided in common to a plurality of subscriber circuits, each subscriber circuit can be downsized and
Economicization will be promoted, and the miniaturization and economicization of the digital exchange will be promoted.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a ring trip circuit according to an embodiment of the present invention. Note that the same reference numerals indicate the same objects throughout the figures.

In FIG. 1, no ring trip circuit is provided in the two sets of subscriber circuits 01 and 02, and a constant voltage diode 20 is used as means for generating different DC voltages when the calling telephone answers. Provided in the calling signal supply path to the subscriber circuit 01, and also connected to the subscriber circuit 01.
The ring trip circuit provided in common to the subscriber circuits 171 and 02 is provided with comparators 171 and 172 and a gate 26 as means for identifying the DC voltage generated in each subscriber circuit.

In FIG. 1, both subscriber circuits 01 and 02 are in a paging signal sending state, and the voltage at the connection point between the paging signal source 4, the constant voltage diode 20, and the resistor 52 of the subscriber circuit 02 is vI, and the subscriber circuit O1 The voltage at the connection point between the resistors 51 and 61 in the subscriber circuit 02 is Vtt, and the resistor 52 in the subscriber circuit 02 is
Let the voltage at the connection point between and 62 be V, and Rt++ =
R*+t −2R16t, R+3” RIs s C
When Ia = Cr h, the output voltage V of the operational amplifier 12 is expressed by equation (5).

Vs = Z+ (Vt Vtt)/R++t+Z+
(Vt Vxz)/Rt++ +VA...αe
When telephones 11 and 12 are both in the on-footer state, resistors 51 and 52 are connected in the same manner as in FIG.
A calling signal of about 30 milliamps maximum flows through each of the channels. Furthermore, Rs+=Rsz-250 ohms, R&t=
R*z=750 ohm, Rqt””R9! = 200 ohms, Riot-50 kilo ohms, R, , =R, □=
RI2= RIs-100 kilohms, CIA=CI
When &=4 microfarads, the output voltage V, a of the operational amplifier 12 is expressed by equation (6).

V sa # 0.43 + V a
(6) On the other hand, when only the telephone set 12 goes off-hook, a DC circuit of approximately 150 ohms is formed in the telephone set 12, and as in FIG. The accompanying maximum value v8. and minimum value Vsr of the output voltage of the operational amplifier 12 are shown by equations (7) and (8), respectively.

V 311= 10 +oc) +0.52
+ AC) + V a
・"(7) Vir=3.5 (.c>"
0.23 (AC) + vA (8) On the other hand, when only the telephone 11 goes off-hook, a DC circuit of approximately 150 ohms is formed in the telephone 11, and the output voltage of the operational amplifier 12 is increased as in FIG. The maximum value of V. and the minimum value v5 are shown by equations (9) and (11), respectively.

Vs*=(10+0.815 Vn) (DC)
+0.52tac> +VA...(9) Vsh= (3,5+0.92V++) (IIC)
+0.23 tacs + V A...α・ (However, ■ゎ is the breakdown voltage of the voltage regulator diode 20) or the breakdown voltage Vゎ is the condition V. 〉■1. such that V
When set to D > 7.4 volts, phones 11 and 1
The off-hook state of No. 2 can be identified by the output voltage of the operational amplifier 12. If we now set vt = 8°2 volts, equations (9) and 11 become as shown in the following equations and equations, respectively.

Vz, = 16.7tec) + 0.52 (AC) + V
A...(11)Vsh-ILne)+0.2
3<ac)+Va (12) The output voltages Vsa to VxhC of the operational amplifier 12 (hereinafter collectively referred to as V) are connected to the non-inverting input terminals of the comparators 171 and 172 (
+), and the threshold voltages v, I, or vrm created by the resistors 23 to 25 are input to the inverting input terminals (-) of the comparators 171 and 172, respectively. Comparators 171 and 172 each have a non-inverting input terminal (
+) and the output voltage V input to the inverting input terminal (-).
A reset signal is output if the output voltage V exceeds the threshold voltage V□ or ■. The reset signal output by the comparator 171 is directly input to the reset terminal R of the flip-flop 21 of the subscriber circuit 01, and also input to the inverting input terminal of the gate 26. Input to the inverting input terminal and further gate 2
The output signal of 6 is the flip-flop 22 of the subscriber circuit 02.
It is input to the reset terminal R of.

Therefore, the threshold voltages V□ and V, ! If set as shown in formula and formula, respectively, V211<Vr+< Vsh
・”(13) Vxa<Vrg< Vst
”(14) Comparator 171 is telephone 1
Comparator 172 outputs a reset signal when either telephone 11 or 12 changes from on-hook to off-hook, and as a result, the gate 26 outputs a reset signal when the telephone 12 changes from an on-hook state to an off-hook state.

As described above, when the telephone 11 changes from the on-hook state to the off-hook state, the flip-flop 21 of the subscriber circuit 01 is reset, the RTI relay 31 is restored, and the transmission of the ringing signal to the telephone 11 is stopped, and the telephone 12 is When the on-footer state changes to the off-hook state, the flip-flop 22 of the subscriber circuit 02 is reset, the RT2 relay 32 is restored, and the sending of the ringing signal to the telephone 12 is stopped.

As is clear from the above description, according to this embodiment, it is possible to stop sending out a ringing signal even when either telephone 11 or 12 changes from the on-hook state to the off-hook state by the commonly provided ring trip circuit. Then,
There is no need to provide a ring trip circuit for each subscriber circuit 01 and 02.

Note that FIG. 1 is only one embodiment of the present invention, and for example, the resistance values of the resistors 5 to 112 and the capacitance values of the capacitors 14 and 16 are not limited to those illustrated, and other values may be used. Many modifications may be considered, but the effects of the present invention will not change in any case.Also, the object of the present invention is not limited to the two sets of subscriber circuits 01 and 02;
Although it is possible to target subscriber circuits of more than one set,
Even in such a case, the effects of the present invention remain unchanged.

〔Effect of the invention〕

As described above, according to the present invention, in the subscriber circuit, the ring trip circuit is provided in common to a plurality of subscriber circuits, so that each subscriber circuit is made smaller and more economical, and the digital exchange is made smaller and more economical. Economicization will be promoted.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a ring trip circuit according to an embodiment of the present invention, and FIG. 2 is a diagram showing an example of a conventional ring trip circuit. In the figure, 1.11 and 12 are telephones, 2.21 and 22 are flip-flops, and 3.31 and 32 are R
T relay, 4 is a calling signal source, 5.6.9.1O111,
13, 15, 18, 19, 23 to 25.51.52.
61.62.91.92.101.111 and 112
is a resistor, 7.8.71.72.81 and 82 are rt contacts, 12 is an operational amplifier, 14 and 16 are capacitors,
17. 171 and 172 are comparators, 20 is a constant voltage converter.
iode. A Leather I A

Claims (1)

[Claims] In a subscriber circuit for a digital exchange, a plurality of subscriber circuits are provided with means for generating different DC voltages when a calling telephone answers, and each of the DC voltages generated in each of the subscriber circuits is identified. A ring trip circuit characterized in that it performs a ring trip operation in common to the plurality of subscriber circuits.