JPS60146560A - Detecting circuit for response of the other party - Google Patents

Abstract

PURPOSE:To detect exactly whether the response of an opposite party exists or not, by deriving the variation of a circuit in polarity by a current flowing to a pair of photocouplers in anti-parallel connection between circuits. CONSTITUTION:A pair of photocouplers 21, 22 are connected in anti-parallel between a circuit L1 and L2. In case the circuit L1 is + and the circuit L2 is -, a light emitting diode of the photocoupler 22 emits light, a photodetector conducts, and a signal line 33 goes to an H level. The photocoupler 21 does not emit light, and a signal line 34 goes to an L level. An AND circuit 29 is turned on and an FF30 is reset by a signal line 36 and provides the output to an output line 32. In this case, the polarity of L1 and L2 is inverted, the signal line 33 and the signal line 34 are inverted to an L level and an H level, respectively, a gate 28 is turned on, and the FF30 provides an output to a signal line 31. In case of an instantaneous disconnection, both the gates 28, 29 turn off. In such a way, the response of an opposite party is detected without any error by detecting exactly the inversion in polarity of the circuit.

Description

TECHNICAL FIELD The present invention relates to a callee response detection circuit for detecting that a called party has answered in a telephone network.

(Prior Art) In a telephone line or network, a called party's response is usually detected as a reversal of the polarity of the potential on the line.

Conventionally, the called party response detection circuit consists of a combination of relays 45, 45', a diode D, and a capacitor C, as shown in FIG. 2. For example, when line L1' is positive and line L2' is negative, relay 45 When line Ll' is negative and line L2' is positive, relay 45' is activated and the called party's response is detected.

Now, in the above-mentioned called party response detection circuit 6, the line Ll
It is necessary that the polarity of the line on the called party's side connected to line L2' and line L2' is determined by the polarity of diode D shown in Figure 2. If the called party answers, the relays 45, 45' will not operate properly and a communication path will not be established between the calling party and the called party.

Another conventional technique is that the other party can detect that the other party has answered regardless of the polarity of the output line of the automatic forwarding telephone device shown in FIG. 3 and the polarity of other lines activated by this automatic forwarding telephone device. There is a response detection circuit, but line L
Every time the polarity of r' and 'L2' was reversed, the output terminals 9 and 10 were in an open state, causing a malfunction in response to a momentary disconnection of the line. The details of the operation of these prior art techniques are disclosed in Japanese Patent Laid-Open No. 57-39652.

(First Embodiment of the Invention) The present invention aims to eliminate the above-mentioned drawbacks, and provides accurate response to the called party regardless of the polarity of the connected line or even if there is a momentary disconnection of the line. The present invention provides a response detection circuit that can detect the state of the other party.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an automatic forwarding telephone device including a counterparty response detection circuit according to the present invention.
When a calling signal arrives at L2, the signal receiving circuit 1 sends a signal to the office line activation control circuit 2. Next, the station line activation control circuit 2
sends a start control signal to the office line starting circuit 3, and the office line starting circuit 3 transfers the output of the MF signal generating circuit 5 controlled by the MF signal control circuit 4 to the line (hereinafter referred to as line) L+'.

Send to L2'. As a result, a preprogrammed MF signal is supplied to lines L,', L2', and the destination telephone is called. When the transferred telephone answers this call, line L,'.

Since the polarity of L2' is reversed, this change in polarity is detected by the called party response detection return path 6, and the communication path 7 is closed.

FIG. 4 is a diagram showing a counterpart response detection circuit according to an embodiment of the present invention, in which L, . . . L2 are calling side lines. Now, assuming that the polarity of the transmitting line is +' and L2 or -'', the light emitting diode of the photocoupler 22 emits light, the light receiving transistor becomes conductive, and the signal line 33 becomes 4" VC.
C” level.

On the other hand, the light emitting diode 1- of the photocoupler 21 does not emit light, and the signal line 34 is at the LOW" level. Therefore, the gate 29
is satisfied, the flip-flop (hereinafter referred to as F/F) 3
0 is reset by the signal line 36 and output 32 is output. Ll here.

If the polarity of L2 changes from the state where Ll is “10” and L2. emits light,
The signal line 34 becomes at the "Vcc" level. In addition, the light emitting diode of the indicator coupler 22 does not emit light, and the signal line 33 is at the "LOW" level. Therefore, K!-28 is satisfied, the F/F 30 is set by the signal line 35, and the output 31 is output. be done.

Similarly, L, , L2 or Ll-I It , r-2"+'
When the state changes to Ll', L, and -', the gate 29 is satisfied and the signal line 32 of the F/F 30 is output.

Even if a momentary line interruption occurs here, Gate 28 or Gate 2
9 was satisfied is no longer satisfied, and signal line 3
5 or the signal line 36 is not output, and the state of the F/F 30 does not change. For this reason F
The state of /F30 is reversed only when the polarity of the line changes, providing an extremely stable counterpart response circuit.

Further, FIG. 5 shows an example of a circuit in which a single pulse is generated from the circuit of this embodiment every time the polarity of the line is reversed.

In the figure, 44 is a one-shot, and the pulse width of the output 47 can be variably set by the values of the connected capacitor 45 and resistor 46.

(Effects) As described above, according to the present invention, it is possible to detect only the reversal of the line polarity based on the called party's response and the completion of the call, regardless of the polarity of the connected line. By using this function to supply a line connection or line release signal to the control circuit of an automatic forwarding telephone device, accurate control can be achieved regardless of the polarity of the connected line or even if there is a momentary disconnection of the line. It is possible to control automatic transfer, etc.

[Brief explanation of drawings]

FIG. 1 is a block 12 showing an automatic forwarding telephone device including a callee response detection circuit according to the present invention, FIG. 2 is a circuit diagram showing a conventional example 1 of the callee response detection circuit, and FIG. 3 is a conventional callee response detection circuit. FIG. 4 is a circuit diagram showing an embodiment of the other party's response detection circuit according to the present invention; FIG. 5 is a circuit diagram showing an embodiment of the other party's response detection circuit according to the present invention; FIG. FIG. 2 is a circuit diagram showing an example. In the figure, L, L2... line, 21.22...
Photocabra, 30...Flip-flop F/F, 44
...It's a one-shot. Figure 1 2nd cause 3rd evil ◇Dan 1U

Claims (1)

[Claims] A counterparty response detection circuit for detecting line connection and line disconnection of a called party in a type of telephone device in which the polarity of the line changes when the called party answers, comprising a photocoupler connected in series to the line, and the photocoupler. detects the current flowing through the line, has two states corresponding to the polarity of the current flowing through the line detected by the photocoupler, and is characterized in that it changes from one state to another each time the polarity changes. A response detection circuit for the other party.