JPS6333753B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a public telephone for consignment use whose management is entrusted to a specific consignee.

Figure 1 is a circuit diagram of the main parts of a conventional example. Normally, a DC voltage with line terminal L ₁ as the positive pole is applied from an exchanger to line terminals L ₁ and L ₂ via the line. , when making a call, if you insert a coin after off-hooking, the hook switch HS ¹ and coin detection contact CCL ¹ turn on, and the line terminal
L ₁ - Hook switch HS ¹ - Diode D ₁ - Coin detection contact CCL ¹ - Dial pulse contact Di - Diode D ₃ - Relay contact rr ² - Transmitter T - Blocking wire
A DC loop of CH ₂ - diode D ₄ - blockage wire CH ₁ - relay contact rr ¹ - line terminal L ₂ is constructed, and the exchange detects this and becomes ready for transmission, and sends out a transmission tone.

When the user confirms the dial tone and makes a dial call, a dial pulse is sent by turning the pulse contact Di on and off.The exchange responds to this and establishes an exchange connection.If the called party answers, the exchange Since a polarity reversal pulse signal with line terminal L ₂ as the positive pole is sent, line terminal L ₂ - contact rr ¹ - blocked wire
CH ₁ - Diode D ₅ - Contact rr ² - Transmitter T - Diode D ₆ - Pulse contact Di - Coin detection contact CCL ¹ -
Diode D ₂ - Relay M as a response detection relay - Hook switch HS ¹ - Relay M is operated by the route of line terminal L ₁ , self-holds by the holding mechanism, and operates until the holding mechanism is reset by the on-hook. maintain the condition.

Then, the circuit of the coin storage magnet (not shown in the figure) is completed, and the coin storage magnet operates in response to the polarity reversal pulse signal, so that when the called party answers, and after that, the unit call time is determined according to the communication distance. Coins are stored in accordance with the polarity reversal pulse signal that is sent out every time the period of time elapses.

In addition, when a ringing signal arrives in the on-hook standby state, the ringing signal is given to the bell BL via the capacitor _C1 and the switch ^HS2 , and when the bell BL rings and an off-hook is performed, the switch ^HS2 is switched. , the half wave of the ringing signal with line terminal L ₂ as the positive terminal is the line terminal
L ₂ - contact rr ¹ - blockage wire CH ₁ - capacitor C ₂ - relay RR as incoming call detection relay - relay contact rr ⁰
- Coin detection contact CCL ² - Key contact KS ¹ - Resistor R ₁
−Hook switch HS ² −Capacitor C ₁ −Line terminal
It is connected through route _L1 , which operates a polarized relay RR using a permanent magnet, which maintains itself.

Then, the contacts rr ⁰ to rr ² switch, and the contacts rr ² exclude the circuits required for transmitting the relay M to the diodes D ₃ to D ₄ , and directly switch the switch.
Configures a direct circuit to HS ¹ , and connects contact rr ¹
In some cases, a side current circuit is completed with a resistor _R2 installed in parallel to a capacitor _C3 for audio current distribution inserted in series with the induction wire IND, and turned on by off-hook. switch
For the DC component superimposed on the calling signal via HS ¹ with line terminal L ₂ as the positive terminal, line terminal L ₂ - contact rr ¹ - resistor R ₂ - guide wire IND - transmitter T - contact rr ² - Hook switch HS ¹ - Since the line terminal L ₁ forms a DC loop, the exchange detects this, stops sending out the ringing signal, and switches to applying DC voltage with the line terminal L ₁ as the positive pole, and the call status is established. shall be.

Therefore, when on-hook is performed after the end of the call, the DC loop is opened by turning off the switch HS ¹ , and at the same time, the short circuit to the relay RR is removed, so that the DC with the positive terminal at the line terminal L ₁ is connected to the line terminal L ₁ . − Contact rr ⁰ − Relay RR − Diode D ₃ − Zener diode ZD ₁ , ZD ₂ − Blockage wire CH ₂ − Guide wire IND − Resistor R ₂ − Contact rr ¹ −
It is connected through the route of line terminal _L2 , and relay RR is restored, and the DC loop is opened by turning off switch ^HS1 , so the exchange is restored accordingly.

In addition, when a call key for free calls owned by the trustee is inserted and operated, the key contacts KS ¹ ,
Since KS ² operates and short-circuits relay M, coin detection contact CCL ¹ , and relay RR, the operation of relay M and relay RR is prevented, and free calls are made possible.

However, in the conventional configuration shown in Figure 1,
If you go off-hook when a call signal arrives, a DC loop is immediately established and the call state is established.
In the case of a system in which the caller pays for calls called collect calls, the disadvantage is that the call can be made even if someone other than the trustee takes off-hook, and calls can only be made when the receiver intervenes. This has come to be demanded.

The present invention aims to eliminate these conventional drawbacks at once, and by adding a directional element,
The purpose of the present invention is to provide an extremely rational public telephone set for use on consignment that prevents anyone other than the consignee from responding, and also allows unspecified parties to respond to calls from special exchange equipment. .

The details of the present invention will be explained below with reference to the main circuit diagram of FIG. 2 showing an embodiment.

In the same figure, the line terminal L ₁ is applied as a positive terminal into the side current circuit formed by the resistor R ₂ , and the communication current is applied to the transmitter T as a forward direction. Diode _D7 is inserted, and even if relay RR operates and completes the side flow circuit by off-hook after receiving a call signal,
The diode _D7 blocks the DC component superimposed on the ringing signal with the line terminal _L2 as the positive terminal, so that no DC loop is formed.This makes it possible for the exchange to detect response operations due to off-hook. Cannot switch to call state.

However, if the trustee operates the call key, the operation of relay RR is blocked, so the off-hook forms a DC loop similar to that used when making a call, and the call state can be entered.

Note that the calling signal is an AC signal with an effective value of approximately 70V, and even if a DC voltage of approximately 48V with line terminal L ₂ as the positive pole is superimposed on it, the line terminal of the calling signal
There is a risk that diode D ₇ will be in a flowing state due to the peak value with L ₁ as the positive terminal, but as will be explained later,
The integration circuit consisting of resistors R ₃ and R ₄ and capacitor C ₄ absorbs the peak current with the line terminal L ₁ of the calling signal as the positive terminal, and the thyristor SCR as a switching element is maintained in the OFF state, so that the switch Malfunctions are reliably prevented.

In addition, special exchange equipment such as 110 number reception desks may put the connection circuit with the other party's phone on hold and then call again. In this case, only the AC ring signal is sent. Therefore, even an unspecified person is required to be able to immediately respond to such a hold re-signal.

For this purpose, in Fig. 2, a thyristor SCR is inserted as a switching element in the DC circuit from contact rr ² to switch HS ¹ , and the detection circuit DET detects the line terminal after the operation of relay RR. When a DC voltage with _L1 as the positive electrode is detected, the thyristor SCR is turned on to form a DC loop. In other words, the incoming call detection relay RR is operated by a ringing signal of only an AC component, and after the ringing signal is sent, a DC voltage applied with the line terminal _L1 as the positive terminal activates an integrator circuit consisting of resistors _R3 , _R4 and a capacitor _C4 . is the resistor R ₄
To charge the capacitor _C4 with the side as the positive pole,
The terminal voltage of capacitor C ₄ increases according to a time constant determined by resistors R ₃ and R ₄ and capacitor C ₄ , and when it reaches the Zener voltage of Zener diode ZD ₃ , current limiting resistor R ₅ increases. By discharging the charge in the capacitor C ₄ through the bias resistor R ₆ and the resistor R 6 , the terminal voltage of the resistor R ₆ is applied to the gate of the thyristor SCR, turning it on.

Therefore, after sending out the ringing signal, the line terminal L ₁
Line terminal L ₁ - Hook switch HS ¹ - Thyristor SCR -
Diode D ₈ - Contact rr ² - Transmitter T - Guide wire ring
A DC loop of IND - resistor R ₂ - diode D ₇ - contact rr ¹ - line terminal L ₂ is formed, and diode D ₇ ,
When _D8 is also turned on by the communication current, communication becomes possible.

Note that while resistors R ₇ and R ₈ exhibit a voltage dividing effect together with resistor R ₃ , resistor R ₈ and diode D ₉ constitute a discharge circuit for capacitor C ₄ , which is different from the general one. Line terminal L ₂ sent out from the exchange
For the peak value of the calling signal with the line terminal _L1 as the positive pole, which is a superimposed DC component with _the positive pole of The time constant is determined by the capacitor _R8 and the capacitor _C4 .

However, the diode _D8 may be inserted into the detection circuit DET, or the thyristor SCR may be replaced with a transistor or the like, and the configuration of the detection circuit DET can be arbitrarily selected accordingly.

Also, as diode D ₇ , metal rectifier,
It is sufficient to use a directional element such as a transistor,
Various modifications are possible.

As is clear from the above explanation, according to the present invention, response operations that do not use the call key are disabled in response to a calling signal sent from a general exchange, and after sending a calling signal containing only an AC component, Since it is possible to respond to a DC voltage with the terminal _L1 as the positive terminal, a remarkable effect can be obtained in public telephones for contract use that handle collect calls and the like.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a main part showing a conventional example, and FIG. 2 is a circuit diagram of a main part showing an embodiment of the present invention. RR...Relay (incoming call detection relay), rr ¹ , rr ² ...
…Contact, C ₃ …Capacitor, KS ¹ …Key contact,
D ₇ ...Diode (directional element), SCR...thyristor (switching element), DET...detection circuit.

Claims (1)

[Claims] 1. A side current circuit that bypasses a capacitor for distributing audio current through the contacts of the incoming call detection relay that operates and maintains itself by off-hook after receiving a ringing signal, and forms a DC loop; A public telephone having a direct circuit that is switched by another contact and excludes a circuit required for making a call, and a key contact that is activated by operating a call key for free calls and prevents the operation of the incoming call detection relay, A directional element inserted into the side current circuit as a forward direction for communication current, a switching element inserted into the direct circuit, and after the operation of the incoming call detection relay, a DC voltage of a specific polarity is detected and the A public telephone for consignment use, characterized in that it is equipped with a detection circuit that turns on a switching element.