JPS6325793Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of 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 is sent to positive polarize the line terminal L ₂ from the line terminal L ₂ - contact rr ¹ - blocked wire ring.
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 operates according to the route of line terminal L ₁ , performs self-holding 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 diagram) is completed, and the coin storage magnet operates in response to the polarity change pulse signal, so that the unit call time determined depending on the call distance and when the call is answered is completed. Coins are stored in accordance with the polarity reversal pulse signal that is sent out every time.

In addition, when a ringing signal arrives in the on-hook standby state, the ringing signal is applied 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 inserted in series with the induction wire IND for passing the audio current, 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 relay RR is removed, so that the DC with line terminal L ₁ as the positive terminal is connected to line terminal L ₁ . − Contact rr ⁰ − Relay RR − Diode D ₃ − Zener diode ZD ₁ , ZD ₂ − Blocking 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 exchanger 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 ,
KS ² operates to short-circuit relay M, coin detection contact CCL ¹ , and relay RR, so that the operation of relay M and relay RR is blocked, 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 purpose of this invention is to eliminate all of these drawbacks of the conventional system at once, and provide an extremely effective public telephone set for use on consignment that prevents anyone other than the consignee from responding by simply adding a directional element. It is something to do.

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.

In addition, the ringing signal is an AC signal with an effective value of approximately 70V, and even if a DC voltage of approximately 48V with the line terminal L ₂ as the positive terminal is superimposed on it, the ringing signal is an AC signal with the line terminal L ₁ as the positive terminal. By head value, diode D ₇
Since there is a risk that the current may flow, it is preferable to set the resistor _R2 , which is normally about 25Ω, to about 200Ω and suppress the flowing current according to the peak value of the calling signal.

In addition, as diode D ₇ , a 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, only the addition of the directional element disables response operations using the call key.
Great effects can be obtained.

[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 ...Contact, C ₃ ...Capacitor, KS ¹ ...Key contact, D ₇
...Diode (directional element).

Claims (1)

[Scope of utility model registration request] It has a bypass circuit that bypasses a capacitor for voice current through the contacts of an incoming call detection relay that operates and self-maintains when off-hook after receiving a call signal, forming a DC loop, and also has a call key for free calls. A public telephone having a key contact which is activated by operating the incoming call detection relay and blocks the operation of the incoming call detection relay, characterized in that a directional element is inserted into the side current circuit so as to direct the communication current in the forward direction. Public telephones for consignment use.