JPH0241943B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a ring strip circuit in a telephone exchange device in which the transmission of a ringing signal is shared by dividing the transmission in phases.

[Conventional technology]

When making a call, the telephone exchange sends a 16Hz alternating current superimposed on direct current as a ringing signal to the telephone, causing the bell inside the telephone to ring. In this case, during a call, the capacitor inside the telephone prevents the direct current component from flowing, only the alternating current component, and when the called party answers, the ring trip circuit detects that the direct current component has flowed, and stops sending out the calling signal. Was. This will be explained using drawings.

FIG. 1 is a diagram showing an outline of a paging signal sending circuit of a private branch exchange device. In the same figure, #0, #
1 and #2 indicate telephone line numbers, and the figure shows three lines as an example.

Data for sending and stopping the calling signal is input from the central processing unit to the data input terminals D of the D flip-flops DL ₀ to _{DL 2} corresponding to each line number constituting the latch circuit 2 via the data bus D ₀ . In addition, each clock terminal CK of the D flip-flops DL ₀ to _{DL 2} is connected to the call selection circuit 1.
are connected to output terminals 0, 1, and 2 of. The call selection circuit 1 also receives a selection signal from the central processing unit.
By A ₀ , A ₁ and write signal WR, the corresponding D
Write timing signal WR ₀ for setting or resetting flip-flops DL ₀ to DL ₂ ,
Output WR ₁ or WR ₂ . This write timing signal causes one of the D flip-flops DL ₀ to DL ₂ to be set.

Now, by call selection circuit 1 #0 telephone
If TEL ₀ is called, the clock signal WR ₀ is input to the D flip-flop DL ₀ , the data supplied from the data bus D ₀ is input to the D flip-flop DL ₀ , and the signal #0 in FIG. 2 is input to the D flip-flop DL 0. The signal is output from the Q terminal of the flip-flop DL ₀ , and the relay RG ₀ is activated, and its contact rg ₀ is inverted.
When this relay contact rg ₀ operates in reverse, 16 Hz alternating current is supplied from the signal device 3 to the telephone TEL 0 through the resistor R ₀ and the relay contact rg ₀ , and the bell of _{the telephone TEL 0 emits} a ringing tone. At this time, a direct current is going to be supplied from the direct current power supply 4 at the same time as the 16 Hz alternating current, but the direct current is cut off by the direct current blocking capacitor (not shown) of the telephone TEL ₀ . telephone
The 16Hz alternating current supplied to TEL ₀ is a relay contact.
It is also supplied to the ring trip circuit 5 through fg ₀ , but since the capacitor C ₀ bypasses this alternating current, the transistor of the ring trip circuit 5
TR ₀ will not operate with this alternating current.

Next, when the called party picks up the handset of the telephone and answers, the DC blocking capacitor mentioned above is bypassed and the DC current is supplied from the DC power supply 4 to the telephone TEL ₀ through the same circuit that the 16Hz AC current passed through. Ru. This DC current causes the ring trip circuit 5 to
A DC voltage is generated across the resistor R ₃ in the transistor, and this voltage charges the capacitor C ₀ and the transistor
TR ₀ turns on, and current flows through the photodiode PD that constitutes the photocoupler PC ₀ connected to its collector. This current turns on the phototransistor _PTr . This phototransistor PT _r
By turning ON, latch circuit 2 is connected to output terminal 1.
A clear pulse is supplied to the D flip-flops DL ₀ to _{DL 2} constituting the D flip-flops DL 0 to DL 2 to clear them. By clearing the D flip-flop DL ₀ , the relay RG ₀ is restored, the relay contact rg ₀ is also restored, and the ringing signal to the telephone TEL ₀ is stopped. And the recipient is the power supply circuit
Calls can be made by receiving power from the GS.
Here, the reason why the photocoupler PC ₀ is used for the ring top circuit 5 is to isolate the ring top circuit 5 and the latch circuit 2 because the DC power supply 4 uses a 48V power source that is different from the power supply for the latch circuit 2. It's for a reason.

As mentioned above, the capacitor C ₀ of the ring trip circuit 5 bypasses the AC power supply for ringing the ringing bells of the telephones _{TEL 0} to TEL ₂ , and
Although it is used to detect off-hook of TEL ₂ , its charging/discharging time constant is set to 40 to 50 ms to prevent malfunction due to noise or the like.

Therefore, for example, if two consecutive lines receive a call at the same time, and the telephone assigned to the previous line is off-hook immediately before the end of ringing signal transmission, a problem occurs in which ringing is lost on the next line. do. Such a ringing phenomenon in the next line will be explained in detail based on the drawings.

[Problem to be solved by the invention]

Figure 2a is a diagram showing the timing of the calling signal,
For example, if the ringing signal is to be sent in a pattern that continues for 1 second and pauses for 2 seconds, the ring trip circuit 5 is shared by three telephones, and #0,
As seen in the waveforms #1 and #2, each phone
TEL ₀ to TEL ₂ are driven in time division. Figure b shows the write timing signals WR ₀ , WR ₁ from the call selection circuit 1, the relay timing signals RG ₀ ,
RG ₁ , transistor of ring trip circuit 5
3 is a diagram showing a timing chart for explaining the reset operation of TR ₀ , photocoupler PC ₀ , and D flip-flops DL ₀ to _{DL 2} of latch circuit 2. FIG.

Now, as shown in figure b, the telephones TEL ₀ and TEL ₁
are called at the same time and the call signal sending timing is #
0, #1, the write timing pulse from the call selection circuit 1 is output as WR ₀ , WR ₁ ,
Relays RG ₀ and RS ₁ operate, and as described above, due to the inverted operation of the relay contacts rg ₀ and rg ₁ , the signal
The 16Hz alternating current ringing current is connected to the signal generator 3 and the resistor.
R ₀ , R ₁ , relay contacts rg ₀ , rg ₁ , telephone TEL ₀ ,
TEL ₁ , relay contact rg ₀ , rg ₁ , telephone TEL ₀ through capacitor C ₀ of ring trip circuit 5,
The signal is supplied to TEL ₁ , and the bells of telephones TEL ₀ and TEL ₁ ring in sequence.

If the called party of telephone TEL ₀ answers at point E just before the end of the write timing of #0, DC power supply 4
A direct current is supplied from the telephone TEL 0 to the telephone TEL ₀ through the DC power supply 4, the resistor R ₃ , the relay contact rg ₀ , the telephone TEL ₀ , the relay contact rg ₀ , and the resistor R ₀ .

The voltage generated across the resistor _R3 due to this DC current causes the transistor of the ring trip circuit 5 to
_TR0 turns on, turning on the photocoupler _PC0 , and its output resets the D flip-flops _DL0 to _DL2 constituting the latch circuit 2, and the relay _RG0 is restored.

However, the photocoupler PC ₀ output is capacitor C ₀
The time for the charge to be accumulated and discharged is approximately 40ms to 50ms.
It will continue for ms. (This time is determined by the time constants of capacitor C ₀ and resistors R ₄ and R _5. ) Therefore, each D flip-flop remains reset during this period. Therefore, even if there is a write timing pulse WR ₁ for calling the telephone TEL ₁ from the call selection circuit ₁ , the relay RG ₁ cannot operate because the D flip-flop DL ₁ has been reset. ).

As explained above, depending on the off-hook timing of the telephone TEL ₀ , the ringing of the telephone TEL ₁ may be interrupted.

This invention was made in view of the above-mentioned points, and a switch circuit consisting of a mono multivibrator and a photocoupler is loaded on the output of the ring trip circuit 5, and the electric charge accumulated in the capacitor is instantaneously discharged by the output, causing ringing. It is an object of the present invention to provide a ring trip circuit having a function of preventing disconnection.

[Means to solve the problem]

In order to solve the above problems, in the ring trip circuit of the present invention, the switch circuit is a monostable multivibrator that outputs a pulse determined by a capacitor and a resistor, and upon receiving the detection signal from the ring trip circuit 5, the capacitor of the switch circuit The capacitor in the ring trip circuit is short-circuited for the time determined by the and resistor. The time determined by the capacitor and resistor of the switch circuit is determined by the repetition time of the ringing signal, the number of telephones that share the ring trip circuit by switching, the constant of the resistor that shorts the capacitor, the probability of calling multiple telephones at the same time, etc.

[Effect]

According to the ring trip circuit of the present invention constructed in this manner, the capacitor in the ring trip circuit is short-circuited after the telephone responds, and the charge accumulated in the capacitor is discharged, so that the ring trip circuit can be restored quickly.

〔Example〕

The present invention will be explained below based on the drawings.

FIG. 3 is a diagram showing a discharge circuit that loads the ring trip circuit 5 of FIG. 1 in order to prevent ringing loss as an embodiment of the present invention. In the figure, ' is an input terminal connected to the output terminal of the ring trip circuit 5 of FIG. 6 is a monostable multivibrator circuit that outputs a pulse with a width of about 1 ms determined by a capacitor C ₁ and a resistor R ₆ . The output terminal ', which is an inversion of the output terminal Q of this monostable multivibrator circuit 6, is connected to the reset terminal of the latch circuit ₂ shown in FIG.
Connected to PD. Further, the collector-emitter of the phototransistor _PTR of the photocoupler _PC1 is connected to terminals 3 and 4 at both ends of the capacitor _C0 of the ring trip circuit 5 shown in FIG.

Next, the operation of the switch circuit added to the ring trip circuit 5 shown in FIG. 3 will be explained with reference to the time chart shown in FIG. 2c.

As mentioned above, when there is a response from the telephone TEL ₀ , the transistor TR ₀ and the photocoupler PC ₀ of the ring trip circuit 5 are activated. Monostable multivibrator circuit 6 is activated by photocoupler PC ₀ .
is activated, outputs a pulse with a width of 1 ms, sends a reset pulse to the D flip-flops DL ₀ to DL ₂ of the latch circuit 2, resets the D flip-flops DL ₀ to DL ₂ , and also activates the transistor PTr of the photocoupler PC ₁ . The charge accumulated in the capacitor _C0 of the ring stop circuit 5 is instantly discharged.
Due to this discharge, the transistor TR ₀ is immediately restored, and the photocoupler PC ₀ is also restored. This allows you to be ready to respond to the next call immediately, and eliminates the worry of missing ringing as in the past.

Further, the reason for using the photocoupler PC ₁ as the switching circuit here is the same as the case of the photocoupler PC ₀ , and it is not limited to photocouplers as long as the insulation is reliable and the response speed is fast.

〔Effect of the invention〕

As explained above, the ring trip circuit according to the present invention includes a switch circuit that operates in response to the output of the ring trip circuit, and the switch circuit discharges the charge accumulated in the capacitor on the input side of the ring trip circuit. Therefore, the recovery of the ring trip circuit becomes faster, and even if multiple lines are called in succession and the response of the previous phase line occurs just before the end of the ring signal transmission, there is no ringing loss due to the recovery delay of the ring trip circuit as in the conventional case. It has a very good effect that it never happens.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a telephone exchange, Figure 2a,
b and c are timing charts for explaining the operation of the telephone exchange device, and FIG. 3 is an additional circuit of the ring trip circuit showing one embodiment of the present invention. In the figure, 1 is a call selection circuit, 2 is a latch circuit,
3 is a signal device, 4 is a DC power supply, 5 is a ring top circuit, 6 is a monostable multivibrator circuit, PC ₁ is a photocoupler, C ₁ is a capacitor, and R ₆ is a resistor.

Claims (1)

[Claims] 1. A telephone set is equipped with a capacitor that determines a charging/discharging time constant for detecting the direct current flowing through the telephone set in response to the response when the telephone set receives a ringing signal sent out in phases from the exchange and the called party responds, In a ring trip circuit that is used commonly for a plurality of telephones by being stopped and switched by a call selection circuit: The ring trip circuit operates upon receiving a detection signal from the ring trip circuit, and short-circuits the capacitor on the input side of the ring trip circuit for a predetermined period of time. A ring trip circuit characterized by being provided with a switching circuit that immediately discharges the charge accumulated in a capacitor after a telephone responds.