JPS60200657A - Polarity inversion signal detecting system of public telephone set - Google Patents

Abstract

PURPOSE:To execute a call accompanied by a normal coin receipt operation only in case a prescribed polarity is connected, by detecting a polarity inversion signal by deciding a generating sequence of an output of a dial operation detecting means and a polarity detecting means. CONSTITUTION:When a dial operation is executed, it is transmitted to a dial number control circuit 600 through a photocoupler CC2. In case it is an inhibition number, a forced releasing circuit 400 is operated through a call control circuit 800, and a call is disconnected forcibly, but in this case, it is used as a dial operation detecting means, as well. Subsequently, when a polarity inversion pulse arrives by a called subscriber's response, a photocoupler CC1 receives it, and it is supplied to the first input of an AND circuit AND3. Also, a polarity inversion pulse detecting signal is sent out to a coin receipt control circuit 900A through an OR circuit OR3, etc. That is to say, a dial operation detecting signal is sent out, and subsequently, a calling service can be executed only in case the opposite polarity is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a pole reversal signal detection method in a public telephone.

[Prior art]

Generally, in public telephones, when a called party answers, a polarity change pulse, which is a pulse signal, arrives from the station, and in order to detect this and accept a coin, it is connected with a predetermined polarity to the station line polarity. There is a need to.

However, in other countries, public telephones are often installed with the wrong polarity because there is no indication of central line polarity when installed, or even if the correct polarity is connected, the polarity is often reversed due to construction work at relay points. In such a case, there was a problem that the coin storage operation could not be performed normally.

For this reason, the applicant proposed that the first . By inserting a photocoupler on each side connected between the second station and memorizing each output to ensure coincidence, polarity reversal signals can be detected normally regardless of the connection polarity. proposed a polarity reversal signal detection circuit (Patent application 118747/1986)
6-43859)).

However, this method requires two sets of photocouplers and their peripheral circuits, and after forming an incoming call response loop at the first office line terminal L2 (→), the incoming call is reversed to the first office line terminal L l (+). When connected to an exchange that performs
In the event of a call collision, there was a risk that the coins inserted to make the call would be lost in response to the incoming call. In particular, by pressing the designated call continuation button after the end of the call, the exchanger can be restored by lifting the handset, and after releasing the button, dial immediately to make the next call as long as there are accumulated coins. This fear is particularly noticeable in devices that have a call continuation function that allows for continuous communication.

[Object and structure of the invention]

The invention was made in view of these circumstances, and its purpose is to detect a normal polarity reversal signal only when a predetermined polarity connection is made with a relatively simple circuit configuration, and to detect a normal coin. It is an object of the present invention to provide a polarity reversal signal detection method for a public telephone that allows a call accompanied by a retracting operation.

In order to achieve this purpose, the invention focuses on the fact that a loop is always formed before a dial operation and that a polarity reversal pulse due to a response from the called party always arrives after a dial operation. A detecting means and a polarity detecting means for detecting that the polarity of the loop is reversed are provided, and a regular polarity reversal signal is detected by the order of dial operation and reverse polarity detection. Hereinafter, the present invention will be explained in detail using Examples.

〔Example〕

The figure is a circuit diagram showing an embodiment of the present invention. In the figure, 100 is a bell circuit which connects a capacitor C1 and a central line terminal Ll as shown in the figure when on-hook.

It is connected between L2 and notifies the patient. 200 is a diode bridge circuit, and the station line terminal L1. This is to obtain a loop current in a constant direction regardless of the polarity of the voltage applied between L2. It is composed of diodes 11)1 to D4, a resistor 1, and a varistor R1, and further forms a DC loop with the station when the second station line terminal L2 (+) has the opposite polarity. On the side of the diode D1, a light emitting element P of a photocoupler CC1 for polarity detection, which will be described later.
i11 is inserted. A power supply circuit 300 supplies the terminal voltage of a capacitor C2 charged via a diode D5 to each part as a power supply voltage VDD. The constant voltage diode ZDI is for stabilizing the supply voltage. 400 is a forced disconnection circuit that forcibly disconnects a call under certain conditions, as will be described later.
1~Q4. It is composed of a constant voltage diode ZD2, resistors R2 to R5, and a capacitor C3. This is a 500-piece dial contact shorting circuit, which is used to constantly short-circuit dial contact J)i so that dial pulses are not sent even if dial contact Di is disconnected. Cyrisk 80H
・11 transistor Qa varistor VR2, resistor R6~R
11,: When I opens, a frost level difference is created at both ends by the light emitting element PD2 of the indenza C4 and the photocoupler CC2. Therefore, even if the dial contact Di is connected, no dial pulse is sent out.In addition, the photocoupler CC
2 is turned on and off by turning on and off the dial contact DI, and transmits a dial pulse to a dial signal control circuit 600 connected to the light receiving element PT2 as described later. In addition, a resistor IJ2 and a capacitor C are connected in parallel to the dial contact Di.
A series circuit with 5 is for extinguishing the spark of the dial contact Di, and 13 is a resistor.

Furthermore, the Ds dial short-circuit contact short-circuits the telephone circuit 700 when sending a dial signal.

In the above configuration, when connected to the normal polarity, that is, the first central office line terminal L 1 (+), the hook switch H8I switches in the opposite direction as shown when the caller goes off-hook. This forms a DC loop including the communication circuit 100, and also connects the diode D4 to the terminal A-.
A light emitting loop of a photocoupler CC3 is formed from the terminal B to the ground terminal via the diode DIO, the resistor 20, and the light emitting element PD3. Note that C1O is a capacitor.

Next, by inserting a coin, the light receiving element 'PT3 of the shift coupler CC3 is turned on, and the first
Give “H” to human power. As a result, the output of the OR circuit ORI becomes "L", the output of the AND circuit ANDI becomes "H", the output of the OR circuit OR,2 becomes "H", and the transistor QI
As a result of turning off O, the short circuit of the dial contact Di by the dial contact short circuit 500 is released. In addition, 2l
-R23 is a resistor. Further, the terminal box indicates an input terminal for an initial reset signal.

After that, when a dial operation is performed, the contact Di is connected to the dial intermittently depending on the dial number, and a dial signal is sent out. This dial signal is sent to the dial number control circuit 600 via the photocoupler CC2 as described above. Reportedly. The dial number control circuit 600 counts the number of digits of the dial signal and the number of pulses for each digit, and prohibits calls to a predetermined specific number or permits free calls. In this case, as will be described later, the forced disconnection circuit 400 is operated via the call control circuit 800 to forcibly disconnect the call, but this is also used here as a dial operation detection means.

That is, since the number of digits of the dial signal is counted as described above, for example, the output of the digit counter can be extracted and used as the dial operation detection output. Therefore, for example, at the end of the third digit of the dial, the dial operation detection signal of "H" is sent from the dial number control circuit 600 to the AND circuit A.
It is fed to the first input of ND2. At this time, since the polarity reversal pulse has not arrived, the polarity is not completely reversed, so the photocoupler CC1 as a reverse polarity detection means remains off, the light receiving element PTl is not conductive, and the flip-flop circuit F
The Q output of the FI is “L”, and the output of the inverter Nvl is “L”.
Since the output of the AND circuit 2 is "H", the output of the AND circuit 2 is "L", and the flip-flop circuit FF2 is set, and its Q output is "H".
” is given to the second input of the AND circuit AND3. Note that 1) 11 is a diode, C1l is a capacitor, and 24
~R26 is a resistance.

In this state, when a polarity switching pulse arrives due to the called party's response, the photocoupler CC1 receives it, and the capacitor C
A flip-flop circuit FFI is set with the output of the differential circuit consisting of 111 resistors R25 and R26, and its Q output is “H”.
" is supplied to the first input of the AND circuit AND3. As a result, both the inputs of the AND circuit AND3 are 'H' and the output is also 'H', so that the capacitor CI2, the resistor R27 and the resistor The coin storage control circuit 9 passes through the differential circuit consisting of 28, the inverter INV2, and the OR circuit OR3.
Sends a polarity reversal pulse detection signal to 00A. Note that the Q output "H" of the flip-flop circuit FFI is connected to the inverter IN.
VI - OR circuit 0RI - AND circuit ANDl - OR circuit Of(, 2, turns on transistor QIO, turns on thyristor 5CRI, and thereby disables subsequent dialing.

Coin storage control circuit 900A receiving polarity reversal pulse detection signal
The storage magnet and drive circuit 900BK (li!! Sends the coin storage signal and operates the frost magnet to store coins. R29 is a storage magnet drive circuit that divides the voltage of the power supply circuit 300. 900B.The coin storage signal is also applied to the call control circuit 800 at the same time, and the call control circuit 800 checks the presence or absence of coins at the leading and trailing edges of the coin storage signal, and detects that there are no coins at the front line. If (coin breakage) trailing edge (thread amount etc.), OR circuit OR4, capacitor C13, resistor 30.R31, inverter IN
A forced disconnection circuit 400 is controlled via a one-shot circuit 1000 consisting of V3. The one-shot circuit 1000 is configured to send out a one-shot output of, for example, 800 m5, which is sufficient for the exchange side to recover, and in response to this, the forced disconnection circuit 400 disconnects the loop during that time.

Note that this embodiment uses a timer multi-charging method.
AND circuit AND which is sent out by the arrival of polarity reversal pulse
The timer circuit 1100 is activated by the output "H" of the clock 3, and thereafter, coin storage is performed by the timer multi signal periodically sent from the timer circuit 1100 via the inverter INV4 and the OR circuit OR3.

On the other hand, if the polarity is reversed, the second station scarlet terminal L 2 (
+), the photocoupler CCI is turned on at the same time as the loop is formed, and after the initial reset is completed, the flip-flop circuit FFI is set and the Q output becomes H''.This causes the output of the inverter INVI to be ``1. +
+ closes the gate of the AND circuit AND2, turns on the transistor QIO, and shorts the dial contact Di.

Therefore, even if a coin is inserted and a dial operation is performed, no dial pulse is sent out, and no dial operation detection signal is sent out. In addition, even if the dial operation detection signal is sent for some reason, the AND circuit AN
Since D2 is closed, no set input is given to flip-flop circuit FF2.

A dial operation detection signal is sent, and then only when reverse polarity is detected can an outgoing call be made.

In addition, if you go on-hook due to an incoming call, the photocoupler CC
Even if I is turned on and the flip-flop circuit FFI is set, the flip-flop circuit FF2 will not be set as in the case of transmission when the reverse polarity is connected as described above, and even if a coin is inserted due to a collision between the sending and receiving calls. Even if it were, the coin would not be stored.

The above description has been made using the front loop force type as an example in which a loop is formed before inserting a coin, but the present invention is not limited to this, and can be similarly applied to the rear loop type. ]' is capable.

In the above embodiment, the dial operation detection signal was extracted from the digit counter of the dial code control circuit, but of course a dedicated dial operation detection circuit may be provided separately, or the dial operation detection signal may be extracted in conjunction with the dial pulse. For example, the output may be associated with the operation of the dial shorting contact Ds.

〔Effect of the invention〕

As explained above, according to the present invention, the dial operation detection means and the polarity detection means for detecting that the polarity of the loop is reverse polarity are provided, and the order of dial operation and reverse polarity detection is determined to determine the order of the dial operation and reverse polarity detection. By detecting the polarity reversal signal, calls are allowed only when a normal connection is established, and in the case of a reverse polarity connection, a call can be made without normal coin storage operation. The inconvenience of allowing polarity detection can be avoided with a simple circuit configuration using one polarity detection means.

[Brief explanation of the drawing]

The figure is a circuit diagram showing one embodiment of the present invention. 600...Dial number control circuit with dial operation detection function, 700...Telephone call circuit, 900A...
Φ・Coin storage control circuit, 900B--・Storage magi,
AND3-...AND circuit, CCI...Photocoupler as a means for detecting authenticity, CC2...Photocoupler for conflict dial pulse detection, FFx, FFz... ...Flip-flop circuit, L1', L2...Polarity terminal. Patent applicant Tamura Kamiso Kosaku 1fi agent Masaki Yamakawa (and 2 others)

Claims (1)

[Claims] A polarity detecting means for detecting that the polarity of a DC loop formed between the station and the station is opposite, and a dial operation detecting means for detecting a dial operation and sending out a detection output at a predetermined timing. 1. A polarity reversal signal detection method for a public telephone, characterized in that a polarity reversal signal is detected by determining the order in which the outputs of the dial operation detection means and the polarity detection means are generated.