JPS6039970A - Polarity inversion detecting circuit - Google Patents

Abstract

PURPOSE:To simplify the circuit by connecting a polarity inversion detecting circuit in parallell with a telephone set to use an incoming collision preventing circuit and a called party response circuit in common, thereby reducing the DC voltage drop of a talking circuit. CONSTITUTION:The polarity inversion detecting circuit 6 is connected in parallel with a telephone set 2 to surpervise trunk lines in polarity. In assuming the polarity of the trunk line L1 as positive and the L2 as negative, a current flows to a light emitting diode of a photocoupler PC4, and when an incoming call arrives within a prescribed time, the polarity of the trunk line is inverted and no talking is conducted because it is judged as the arrival of the incoming signal. When no incoming signal reaches within a prescribed time, the trunk line is acquired by opening an st contact and closing contact h1, h2 to transmit an opposite subscriber number. When a called party responds, the polarity of the trunk line is inverted and the polarity of the output of photocouplers PC4 and PC5 is inverted. In selecting resistance values as R1>R2, then the photocouplers are activated stably.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polarity reversal detection circuit for a central office line for detecting a called party's response and preventing incoming call collision in an automatic reporting device or the like connected to a telephone circuit.

In order to avoid notifying an incoming call when an automatic notification device attached to a telephone makes an automatic notification, it is necessary to send a selection signal after confirming that no incoming signal has arrived at the telephone. Yes (this is called incoming collision prevention).

Also, the notification needs to be sent after the selection signal is sent and after the called party answers.

By the way, in the current telephone switching network, as shown in Figure 1, when communicating between telephone terminals, the calling side and the called side use A-TE.
There is a state in which the polarity of the station line L1 and L2 terminals is reversed several times before mutual communication starts. That is, on the calling side, when the receiver picks up the handset (off-footer) and operates the dial to send a selection signal), and the called side goes off-hook (response), and on the called side, when a ringing signal arrives and when the call goes off-hook. .

Since the polarity reversal upon arrival of the above-mentioned ringing signal occurs independently of the 16 Hz bell ringing signal, the polarity reversal occurs simultaneously with or in advance of the 16 Hz bell ringing signal. Therefore, when making automatic notifications, even if there is a pause in the 16Hz bell ringing signal, the polarity reversal described above will be detected.
If the device is controlled using the detection signal, collision of incoming calls can be prevented.

On the other hand, if no incoming signal has arrived, after acquiring the station line,
If a selection signal is sent, the called party is called, and the polarity reversal of the office line is detected when the called party answers, the device can be controlled by the detection signal and a predetermined notification operation can be performed.

A conventional example for detecting such a polarity reversal operation is shown in FIG. 2, which is a station line circuit diagram of an automatic notification device. Changeover switch TKi between station circuit 1 and telephone 2 of automatic reporting device
~ Switch and connect TK4 to the automatic notification device side, connect one end of the device start-up make switch s to one of the office lines L1 and L2, and connect the photocoupler PCI to the other end.
It has an incoming collision prevention circuit in which a light emitting diode and a high resistance R1 are connected in series to the other station line, and the polarities of the light emitting diodes of the two photocouplers PC2 and PC3 are opposite to each other. A called party response detection circuit 4 was provided which was connected in parallel to the 8 wires and serially connected to the 8 wires.

However, in this conventional called party response detection circuit 4, since a photocoupler light emitting diode is provided in series with the office line, a DC voltage drop occurs on the office line due to the light emitting diode, and the equivalent series resistance of the device increases. In some cases, it was necessary to limit the subscriber line length.

Furthermore, since the incoming call collision prevention circuit 6 and the called party response detection circuit 4 are provided independently, the number of components increases, which is not economical.

The present invention has been made in view of these conventional drawbacks.Next, the present invention will be explained in detail based on the drawings.

FIG. 6 is a station line circuit diagram of an automatic notification device showing an embodiment of the present invention, in which 5 is a calling signal detection circuit DET for detecting a 16H2 calling signal, 6 is a polarity reversal detection circuit, and 7 is a selection signal. Sending circuit, 8 is a message sending circuit, s t is a starting make switch, which is not shown in the drawing, is the contact of starting relay sT, hl, R2 is a holding make switch that is used to capture the station line, and is not shown in the drawing. Relay■] contacts, R1, R2
is a resistor in the relationship R1)R2, and R1 has a particularly high resistance.

PC4 and PC5 are connected to each other, and the collector and emitter of each transistor are connected to the control section of the automatic notification device. The same symbols as in FIG. 2 indicate equivalent parts.

FIG. 4 is a block diagram of the control unit of the automatic notification device that is controlled by the output signals of the photocouplers PC4 and PC5 in the polarity reversal detection state B, which detect polarity reversal. Reference numeral 9 indicates the input of the activation signal of the device, 10 indicates an input signal monitoring circuit, 11 indicates a control circuit, and 12
16 is a dial number storage unit, 16 is a phosphor drive circuit, 131
132 is a starting relay ST, and the same reference numerals as in FIG. 6 indicate the same parts.

FIG. 5 is a time chart 1- showing the polarity reversal detection state of the self-exciting notification device. The same reference numerals as in FIG. 4 indicate equivalent parts.

Further, the arrows indicate the out-of-sequence of operations regarding each signal.

Next, the operation will be explained.

When an activation signal (fire, theft, or other input signal) is input to this device, a signal is input to the control circuit 11 via the input signal monitoring channel 10. At this time, if an incoming call is already incoming, there is a signal from the 16Hz ringing signal detection circuit 5, so no notification operation is performed; however, if the incoming call is incoming, the control circuit 11 drives the ST relay via the link drive circuit and close the st contact Ll-TKl -5t-R1-PC4-TK12
The i-R2 (7) loop monitors the polarity of the office line for a certain period of time (since the 16H3 ringing signal is an intermittent signal that rings for 1 second and pauses for 2 seconds, at least 2 seconds, which is the same as the pause time of the 16Hz signal).

Now, if the R1 side of the office line is positive and the R2 side is negative, current flows to the light emitting diode side of the photocoupler PC4, and if a call is received within the certain period of time, the polarity of the office line is reversed, and the current photocoupler P050 Flows into the light emitting diode. The change in polarity at this time is detected by inverting the potentials of the output transistors a and b of the output transistors of the photocouplers PC4 and pc5 shown in FIG. It is determined that a signal has arrived, and the ST link 13 is activated via the relay drive circuit 13 without performing any reporting operation.
Restore 2, press S and open the contact.

This operation is shown by time chart 1 in FIG. 5(A).

On the other hand, if the incoming signal does not arrive within the certain period of time, there is no change in the potentials of the outputs a and b of the transistors (the signal from the control circuit 11 is passed through the relay drive circuit 15 to
Restore the relay, open the st contact, operate the B relay, close the hl and h2 contacts, capture the office line, drive the selection signal sending circuit 7, and join the other party already stored in the dial number storage unit. send the user number.

After sending the selection signal, the control circuit 11 again drives the ST relay via the drive circuit 13 to close the st contact and prepare for the arrival of the called name response detection signal.

When a called party is called and the called party answers, the polarity of the office line is reversed, and the R2 side becomes positive and the R1 side becomes negative, and the photocouplers PC4 and P
The polarity of each output a, b of C5 is reversed. Here, R1 is selected to have a high resistance so that the current flowing through the loop formed when an incoming call is detected will not be considered as a central office line capture by the exchange side, and R2 is a value that is such that the current flowing through the loop formed when an incoming call is detected is not regarded as central office line capture, and R2 is such that a communication path is formed after the central office line is captured and the central office line L1 Since the DC voltage between . Outputs a and b of the photocouplers PC4 and PC5
When the called party response is detected by reversing the potential of
The control circuit 11 restores the ST relay via the link drive circuit 13, opens the contact, disconnects the polarity reversal detection circuit 6, drives the message output path 8, and transmits a predetermined message. This operation is shown in the quim chard of FIG. 5(B).

In the explanation, the normal polarity of the office line is positive on the R1 side and negative on the L2 side, but the normal polarity of the office line is negative on the R1 side and negative on the R2 side.
The effect is the same even if the side is positive.

In the embodiment, both the starting meter switch and the holding meter switch are relays as metal switches, but it is clear that they can be replaced with electronic switches. Furthermore, when sending a message, the polarity reversal detection circuit is disconnected in this explanation, but if R2 is connected even while sending a message, the polarity reversal caused by the callee can be detected and the notification can be stopped immediately. becomes possible.

As explained below, according to the present invention, since the polarity reversal detection circuit is connected in parallel to the telephone set, the DC voltage drop in the communication circuit is small, and the incoming call collision prevention circuit and the called party response Since the detection circuit is shared, the circuit is simple and can be configured with fewer parts.
Its practical effects are extremely significant.

[Brief explanation of drawings]

Figure 1 is an operational diagram showing the polarity reversal of a telephone line, and Figure 2 is a central office line circuit of an automatic reporting system showing a conventional central office line reversal detection circuit.
FIG. 6 is a station line circuit of an automatic notification device showing an embodiment of the present invention, FIG. 4 is a block diagram showing a control section of the automatic notification device, and FIG. 5 is a time chart showing a polarity reversal detection state.
- Office line circuit of automatic reporting device, 2... - Telephone, RO... Incoming call collision prevention circuit, 4... Called party response detection circuit, 5... - 16H2 ringing signal detection circuit, 6...
Polarity reversal detection circuit, 7... selection signal sending circuit, 8...
...Message sending circuit, 9...-Start signal, 10.
・・Input signal monitoring circuit, 11・・Control circuit, 12・
... Dial number storage section, 13... Relay drive circuit, 131 - Holding relay, 1 and 2, Starting relay, PC1 to PC5... Photo coupler, Ll, R2...
Central line, T K 1-T type IH・I Start valve 41 (I'1) (I'1 Figure 5 Figure 4 CB) Figure 5I

Claims (1)

[Claims] In a device that is connected to a central office line and has the function of preventing incoming call collision and detecting a called party response, the polarities of the light emitting diodes of two photocouplers are connected in parallel with each other in opposite directions, and 70 circuits and the device are activated. One end of a series circuit formed by connecting a meter switch and a resistor R1 in series is connected to one side of the office line, and the other end is connected to the other side of the office line, and the holding device is used to capture the office line. meter switch and R1)
A circuit in which resistors R2 connected in series is connected to the resistor R2.
1. A polarity reversal detection circuit characterized by being provided in parallel with 1.