JPH0332125Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a telephone line switching circuit (a circuit designed to stabilize and improve operation) devised by the present inventor.

For telephones, especially emergency telephones installed on expressways, etc., the telephone is connected to regular and backup telephone lines, and if there is a telephone that is already using the regular line, it is possible to make calls using the backup line. There is something to do.

Conventionally, when the handsets of multiple telephones were lifted at the same time and the multiple telephones were connected to a regular line, the self-holding relay in the telephone circuit did not recover even when the handsets were hung, and the line remained closed. This may cause some inconvenience in use.

In order to eliminate the above-mentioned drawbacks, the present invention restores the self-holding relay and opens the line by inserting a capacitor in series with the recovery circuit through which the recovery current of the self-holding relay flows when the switch is restored. It was designed to let you do so.

Furthermore, even if the self-holding relay fails to recover, the capacitor can open the line.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

Fig. 1 is a line switching circuit diagram of the telephone device devised earlier, where A is a self-holding relay (hereinafter referred to as a relay), and is a polarized relay, with a ⁰ , a ¹ ,
a ² and a ³ are the contact points. Especially a ² and a ³ are early
It is a make contact.

The self-holding relay used in this invention uses a permanent magnet, and by applying a voltage in the forward direction to the coil, the magnetomotive force of the coil and the attractive force of the permanent magnet are added, attracting the armature and connecting the contacts. The coil continues to be held by the force of the permanent magnet even if the forward voltage in the coil disappears.

The recovery operation is to apply a voltage in the opposite direction to the coil,
The magnetomotive force of the coil and the attractive force of the permanent magnet cancel each other out to restore the armature and the contact.

Telephones TEL1 to TELN are connected to a telephone line. 1 and 2 are regular lines, and 3 and 4 are protection lines, and their polarities are normally positive (+) for lines 2 and 4 and negative (-) for lines 1 and 3. diode
D ₅ and resistor R ₁ connected in parallel and capacitor
C ₁ is connected in series with self-holding relay A.
Contact A is inserted in parallel with the break contact of ⁰ . D ₃ is the diode through which the telephone current of the service line flows, and D ₄ is the diode through which the telephone current flows when the protection line is used.

When the telephone operator lifts the handset of telephone TEL1, the switch (contact point) HS in Figure 1
operates, line 4 (+) - contact a ³ - contact a ⁰ - relay A - speech circuit TC - hook switch HS - contact a ²
- Relay A is activated by the loop of line 3 (-). When contact a ⁰ leaves its break side, relay A has contacts a ² and a ³ as early make contacts, so line 4 (+) - contact a ³ - diode D ₅ - capacitor C ₁ - relay A - A charging current flows through the capacitor C ₁ through the communication circuit TC - the hook switch HS - the contact a ² - the line 3 (-), and the relay A is maintained in operation until the contact a ⁰ switches.

When the switching operation of contact a ⁰ is completed, line 2 (+)
-Contact a ³ -Contact a ⁰ -Diode D ₃ -Talking circuit TC
-Hook switch HS -Contact a ² -Speech current flows through the loop of line 1 (-), allowing the operator of the telephone to talk to a contact.

Note that resistor _R1 is designed to prevent a large current from flowing through relay A that would restore relay A due to the discharge current of capacitor _C1 after contact ^a0 switches to the diode _D3 side. be.

When regular lines 1 and 2 are used, the polarity of only the protection line side is reversed by a switch (not shown) at the contact point, and becomes line 4 (-) and line 3 (+).
For this reason, telephones other than those using regular lines
To call the destination from TEL2, when I lift the handset, the hook switch HS works, but the relay A
does not operate, line 3 (+) - contact a ² - hook switch HS - speech circuit TC - diode D ₄ - contact a ³
-Loop of line 4 (-) is created. Therefore, even if the regular line is in use, it is possible to talk to a contact using the protection line.

If both the regular line and the protection line are already in use, when the handset of the new telephone is picked up,
The telephone call circuit is connected to the backup line,
You can hear the content of the call on the phone TEL2, which is using the backup line first. However, calls from this telephone are restricted under the control of the exchange. For the operator, if he/she can hear the contents of a call on another telephone, the telephone may display a message indicating that the line is in use.

When the telephone that is using the regular line ends the call and hangs up the handset, the switch returns to line 2 (+) - contact a ³ - contact a ⁰ - diode D ₃ - relay A - contact a ¹ - Futsuku Switch HS
- Contact a ² - Current flows through the recovery circuit of relay A of line 1 (-). Therefore, the self-holding of relay A is released, the contacts of relay A return to their original state, and the telephone returns to the standby state.

Next, a case will be described in which the handsets of a plurality of telephones (for example, three telephones TEL1, TEL2, and TEL3) are picked up simultaneously by a plurality of telephone operators.

Since these telephones are installed on expressways, etc., the length of the line facilities is long, and they are designed to operate with sufficient margin even if the line resistance is quite high, so if the telephone is located near a switchboard, three telephones can be installed. It may still work even if connected. The contact operations of the self-holding relay A are the same as when the handset of one telephone is lifted up, as described above. In other words, telephones TEL1, TEL2, and TEL3 are all line 2 (+)
-Contact a ³ -Contact a ⁰ -Diode D ₃ -Talking circuit TC
-Hook switch HS -Contact a ² -A talking current flows through the loop of line 1 (-), and each telephone set and the contact point are in a talking state.

After the call ends, when the handset of one telephone TEL1 is put down, the switch HS is restored and the following current flows through the self-holding relay A. Line 2 (+) - Contact a ³ - Contact a ⁰ - Diode D ₃ - Relay A - Contact a ¹ - Hook switch HS - Contact a ² -
Line 1 (-). However, since the regular line is connected by a telephone with the handset up, other than the telephone with the handset down, the voltage between the regular lines near where the telephone TEL1 is connected is low. There will be particularly low voltages across the service lines, especially if other telephones with their handsets raised are located close to the exchange (usually at the destination).

Below, as an example, three adjacent telephones TEL _o-1 , TEL _o ,
Explain TEL _o+1 .

In addition, the DC resistance of self-holding relay A inside the telephone shall be 1100Ω, and it shall operate and recover at 10mA.

Also, the DC resistance of the telephone communication circuit TC is 200Ω.

FIG. 3 is a circuit diagram when three telephones are connected to a regular line.

In Fig. 3, telephones TEL _o-1 , TEL _o ,
If the handset of TEL _o+1 is picked up at the same time, the resistance of telephones TEL _o-1 , TEL _o , TEL _o+1 is 1300Ω
[Self-holding relay (1100Ω) + communication circuit TC (200Ω)
Ω)]. The current i o _{+1 flowing through the telephone TEL o +1} is
Assuming 10mA, the telephone TEL _o-1 from the exchange
The path resistance R _L up to this point is 522Ω. However, 500m
The line resistance between telephones installed at intervals is 100Ω.

When the handset of one of the three telephones TEL _o+1 is put down, the telephone TEL _o-1 , TEL _o
Since the regular line is connected to the communication circuit TC, the DC resistance of the telephone TEL _o+1 with the handset off is 200Ω.
Since HS returns, the DC resistance of self-holding relay A becomes 1100Ω. Therefore, the current i o _{+1 flowing through the telephone TEL o +1} is 2.7 mA, which is less than 10 mA, so the telephone TEL _o+1 with the handset removed
Self-holding relay A will not recover.

Furthermore, when the handset of telephone TEL _o+1 is taken down, and then the handset of telephone TEL _o is taken down,
Only telephone TEL _o-1 is 200Ω, telephone TEL _o ,
TELn+1 is each 1100Ω, the current i _o flowing through the telephone TEL _o is 5.13 mA, and the current i _{o+1 flowing through the telephone TEL o +1} is 4.7 mA, both of which are less than 10 mA. Therefore, the self-holding relays A of the telephones TEL _o and TEL _o+1 are not restored, and the communication current i o _{-1 of the telephone TEL o -1} is 33.1 mA. This current has a considerably lower audio level than the current of 41.3 mA that flows when only one telephone TEL _o-1 is connected to the regular line.

In addition, the handset and receiver of telephone TEL _o-1 is also a telephone.
When the handset is put down in the same way as the handset of TEL _o , TEL _o+1 , the telephone TEL _o-1 , TEL _o , TEL _o+1 is calculated.
The currents flowing in are 13.2mA, 11.25mA, and
10.3mA, telephone TEL _o-1 , TEL _o , TEL _o+1
Internal self-holding relay A is restored in this order.

If a self-holding relay on a certain telephone set were to become operative due to some adverse conditions, for example, due to dirt entering the contacts, the service line would remain closed and the relay would become unusable. Alternatively, the communication current may decrease, resulting in problems such as a low voice level.

The present invention eliminates the above-mentioned drawbacks, and
This will be explained below with reference to the drawings.

FIG. 2 is a circuit diagram of a line switching circuit showing an embodiment of the present invention. _C2 is a capacitor inserted in series in the path through which the restoration current of self-holding relay A flows. R ₂ is a resistor and the switch HS ₂ has a second make contact.
It discharges the capacitor _C2 when it operates.

First, when the telephone operator picks up the handset of one telephone TEL1, the telephone TEL1 is connected to the regular lines 1 and 2, since the circuit for making a call by the telephone operator is the same as that shown in FIG. After the call on the telephone TEL1 using the regular line ends, when the handset is put down, the hook switch HS ₁ equipped with the first break contact returns, and the line 2 (+) - contact a ³ returns. - Contact a ⁰ - Diode
D ₃ - relay A - contact a ¹ - capacitor C ₂ - hook switch HS ₁ - contact a ² - current flows in the loop of line 1 (-) until capacitor C ₂ is charged.
This charging current restores the self-holding relay,
Telephone TEL1 is released from the regular line.

Next, a case will be described in which the handsets of a plurality of telephones (for example, TEL1, TEL2, and TEL3) are lifted up at the same time in the line switching circuit of the present invention.

This lifting operation of the handset activates relay A in the same way as in FIG. 1, creating the following loop.

Line 2 (+) --- | | | -- | | | | --TEL1 contact a ³ ---Contact a ⁰ ---Diode D ₃ ---TEL2 contact a ³ ---Contact a ⁰ ---Diode D ₃ ---TEL3 contact a ³ -- Contact a ⁰ -- Diode D ₃ -- Call circuit TC -- Hook switch HS
₁ ---Contact a ² Talk circuit TC ---Hookup switch HS ₁ ---Contact a ² Talk circuit TC ---Hookup switch HS ₁ ---Contact a ² -- | | --| --| | | | --| Line 1 (-) In the above loop Therefore, multiple telephones TEL1,
TEL2 and TEL3 allow you to talk to your contacts.

One phone that uses a regular line
After the telephone call on TEL1 ends, when the handset is put down, the hook switches _HS1 and _HS2 are restored, and the following current flows through the self-holding relay A.

Line 2 (+) - contact a ³ - contact a ⁰ - diode D ₃
- Relay A - Contact A ¹ - Capacitor C ₂ - Hook switch HS ₁ - Contact A ² - Line 1 (-). In this circuit, current flows until capacitor C ₂ is charged, but since two telephones are still connected to the regular line, the voltage is small due to the small DC resistance between the regular lines 1 and 2, so this charging Depending on the current, self-holding relay A may not recover. Capacitor C ₂
When the phone is charged, no current flows and the phone
TEL1 becomes the same as if it were disconnected from the line. Next, when the handset is put down, the telephone TEL2 operates in the same manner as the telephone TEL1 described above. Finally, when the handset of telephone TEL3 connected to regular lines 1 and 2 is put down, line 2 (+) - contact a ³ -
Current flows through the path of contact a ⁰ - diode D ₃ - relay A - contact a ¹ - capacitor C ₂ - hook switch HS ₁ - contact a ² - line 1 (-). At this time, the winding of relay A of only telephone TEL3 is connected to the regular line, so the DC resistance between lines 1 and 2 is high and the DC voltage is kept high.
When you hang up the handset of TEL2, an extra current flows through the self-holding relay, and self-holding relay A
can be restored.

After the above-mentioned operation is completed, the telephone TEL1 whose self-holding relay A maintains operation is connected to the regular line.
TEL2 is connected, but no current flows between the regular line and the telephone, so the situation is the same as if it were open. Therefore, if you pick up the handset of a telephone other than telephones TEL1 and TEL2, it is the same as lifting the handset of only one telephone as described above.

Next, when you lift the handset of telephone TEL2 with self-holding relay A in operation, self-holding relay A is in the operating state, so the switch is turned on.
HS ₁ works, immediately line 2 (+) - contact a ³ - contact
a ⁰ - Diode D ₃ - Telephone circuit TC - Hook switch HS ₁ - Contact a ² - Current flows in the loop of line 1 (-). At the same time, the hook switch _HS2 also operates, so that the charge stored in the capacitor _C2 is discharged in the loop of the capacitor _C2 , the hook switch _HS2 , and the resistor _R2 .

After the call ends, when the handset of the telephone TEL2 is put down, the self-holding relay A is restored. In this way, when the handset of the telephone is lifted up and taken down again, the initial state is returned to.

If the regular line is already connected to telephone TEL1, and the handset of telephone TEL2, on which self-holding relay A is already activated, is lifted, the telephone
TEL2 is never connected to the protection line and remains connected to the regular line. Telephone TEL2 is a telephone that uses the regular line under the control of the exchange.
I can listen to the call content on TEL1, but I cannot talk to my contacts. For the telephone operator, if the regular line is already in a call state from a telephone other than the one that made the call, if you hear the content of the call, as explained earlier, it indicates that the line is in use and that you should call again after the call ends. All you have to do is display it on the front of your phone. In this telephone TEL2, when the regular line and the protection line become unused, the handset is lifted up, and when the handset is later put down, the built-in self-holding relay A is released and returns to the initial state.

As explained above, the telephone line switching circuit of the present invention can be used by simply inserting a simple circuit, and when the handsets of multiple telephones are picked up at the same time and then taken down one by one, The advantage is that it prevents a drop in the speech level of a telephone whose handset is raised, and that it can operate reliably even if the self-holding relay inside the telephone is continuously activated due to some adverse conditions. There is.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of the telephone line switching circuit that we devised earlier, Figure 2 is a circuit diagram of the telephone line switching circuit that is an embodiment of this invention, and Figure 3 is a circuit diagram of the line switching circuit of a telephone that we devised earlier. It is a circuit diagram when connected. TEL1~TELN...Telephone, TC...Telephone circuit,
A... Self-holding relay, a ⁰ , a ¹ , a ² , a ³ ... Contact of self-holding relay A, D ₁ , D ₂ , D ₃ , D ₄ , D ₅
...Diode, R ₁ , R ₂ ...Resistor, HS,
HS ₁ , HS ₂ ... Switch contacts, C ₁ , C ₂ ...
...Capacitor, 1, 2... Commonly used circuit, 3, 4...
Protection line, 5...exchange, 6...relay,
TEL _o-1 , TEL _o , TEL _o+1 ...Telephone, R _L ...Line resistance.

Claims (1)

[Scope of utility model registration request] In a telephone line switching circuit in which a plurality of telephones are successively connected to two pairs of telephone lines via the contacts of a self-holding relay, one end of each of the self-holding relay A and the first diode _D3 is connected to the telephone circuit TC. The other end of the self-holding relay A is connected to the contacts a ⁰ and a ¹ of the self-holding relay A, and the other end of the first diode D ₃ is connected to the contact a ⁰ of the self-holding relay A. and inserting a first capacitor C ₁ in parallel with the contact a ⁰ of the self-holding relay A between the other end of the self-holding relay A and one of the regular lines 2 or one of the protection lines 4, A first diode is connected between the communication circuit TC to which the first diode _D3 is connected and one of the regular lines 2 or one of the protection lines 4.
A second diode _D4 is inserted so as to have the opposite polarity to _D3 , and the communication circuit TC is connected to one of the regular lines 2 or one of the protection lines 4 through the communication circuit TC.
and the other line 1 of the regular line or the other line 3 of the protection line forming the loop,
The make contact of the self-holding relay _A is inserted, and ^{one contact a1} _of the self-holding relay A is inserted between the other end of the self-holding relay A and the break contact of the first switch HS1. Insert a second capacitor _C2 in series in the recovery circuit of holding relay A,
A series connection of a resistor and the make contact of the second switch _HS2 is connected to the second capacitor.
Connected in parallel with C ₂ , and during a call, early make contact a ³ of self-holding relay A - contact a ⁰ of self-holding relay A - first diode D ₃ - talking circuit
TC - First switch HS ₁ - Forms a loop with one side of the service line ² or one side of the protection line 4 through the early make contact a 2 of self-holding relay A, and when self-holding relay A is restored, , early make contact a ³ of self-holding relay A - contact a ⁰ of self-holding relay A - first diode D ₃ - self-holding relay A - contact a ¹ of self-holding relay A
- second capacitor C ₂ - first hook switch
HS ₁ - Early make contact of self-holding relay A
A line switching circuit for a telephone, characterized in that it forms a loop with one side 2 of a regular line or one side 4 of a protection line via ^a0 .