JPS5812785B2 - Rusbandenwasouchi Niokeru Shingohanbetsu Cairo - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a signal discrimination method for a telephone terminal device such as an answering machine, which can distinguish a voice signal from an intermittent signal such as a busy tone, a continuous signal such as a dial tone, and a no-signal state. It is related to circuits.

For example, in an answering machine (hereinafter simply referred to as the device), the device is kept in operation via an audio switch while voice signals from the customer are continuously being applied, and all voice signals of the customer are recorded. When the user finishes using the device and puts down the handset, the station will emit a busy tone (depending on the region).
Intermittent signal), dial tone (continuous signal), or no signal.

However, the above-mentioned intermittent signal or the above-mentioned continuous signal causes the device to malfunction (unable to return to the standby state) via the audio switch circuit.

Conventionally, in order to prevent the above-described malfunction, a method using, for example, a filter circuit is known.

However, this method tends to cause malfunctions due to harmonics, and it is difficult to expect reliable operation.

Further, most of the conventional signal discrimination circuits are ineffective for intermittent signals having different amplitudes (Fig. S in Fig. 6).

The present invention has been made to improve the above-mentioned drawbacks, and when the caller finishes using the device and hangs up the handset, the signal tone ( An object of the present invention is to provide a signal discrimination circuit that is not affected by the amplitude and frequency of a continuous signal or an intermittent signal, and the period of a signal portion and a non-signal portion of an intermittent signal.

Next, the operation will be specifically explained with reference to the accompanying drawings.

FIG. 1 shows a signal discrimination circuit showing one embodiment of the present invention, in which 1 is a first switching circuit, 2 is a second switching circuit, 3 is a flip-flop circuit (hereinafter abbreviated as FF circuit), and 4 is a timer circuit. be.

FIG. 2 illustrates the hysteresis characteristics of the first and second switching circuits described above.

Figure 3 shows the voice signal, Figure 4 shows the busy tone.
FIG. 5 is an explanatory diagram of operation points for a dial tone, and FIG. 6 is an explanatory diagram of operation points for an intermittent signal having a different amplitude, which is employed in some foreign stations.

First, to briefly describe the configuration of the device that employs the circuit shown in FIG.
The charge on C3 continues to hold relay Y in operation, keeping the telephone line closed through the relay's contacts (not shown) until the caller has finished using the device. When the above continuous signal or intermittent signal is applied to the above input terminal IN, or no signal is applied to the above input terminal IN, charging of the above C3 will stop, and the charge of this 03 will stop discharging after a predetermined time. It is configured to restore relay Y (after 7 seconds, for example) and put the device into a standby state.

Such a configuration is known. "When an audio signal is applied" First, the operation when an audio signal is applied to the input terminal IN will be described.

By the way, when the device is activated by a call signal, power is supplied to each circuit as shown in the figure.

At this time, assuming that no signal is applied to the input terminal IN, the transistor Q1 of the first switching circuit 1 is OFF.
, Q2 are ON and Q3 is OFF, so the collector of Q3 is at H level as shown in FIG.

Further, the transistor Q4 of the second switching circuit 2 is turned off.
F and Q5 are ON, so the collector of Q5 is at L level as shown in FIG.

For the FF circuit 3, a positive edge trigger type SN7470 was used in the example.

The FF circuit 3 has a preset terminal 13 and a clear terminal 2.
When both are at L level, Q and Q output terminals 8 and 6 are cleared to L level, and when both terminals 13 and 2 are at H level, they are preset.

Here, when an audio signal as shown in FIG. 3A is applied, the voltage is doubled and rectified by the diodes D1 to D4, and the capacitor C1. Smoothed with C2.

The operating level of the first switching circuit 1 (Q1, Q2, Q3) is V2 shown in Figure A, and the operating level of the second switching circuit 2 (Q
4. Since the operating level of Q5) is V1, the collector voltages of Q3 and Q5 are as shown in Figures B and C.

Therefore, as described above, the FF circuit 3 is preset during the time axis t1 to t10, which is the period during which Q5 maintains the H level.

However, at this time t1, the output terminal 8 (Q output) is at the L level as shown in Figure D.

Since this FF circuit is a positive edge trigger type, the time point t2 indicated by the arrow in Figure B. t4, t6, t8. t1
At 0, the output is inverted.

Figure D shows the output of this FF circuit. Further, this output is applied to the timer circuit 4 via the resistor R13.

That is, during the period when the output terminal 8 is at H level, the transistor Q6 is ON and the transistor Q7 is OFF.

Figure E is the collector voltage of Q7, and the collector of Q7 is H.
level, resistor R10 and reverse current blocking diode D
At the same time, transistors Q8 and Q9 are turned on via the semi-fixed resistor VR to operate the load relay Y, and while Q7 is at L level, the charge of C3 causes the capacitor C3 to be charged. Since Q9 is maintained in the ON state, relay Y can be continuously maintained in the operating state.

In the circuit of the present invention, the resistance value of the resistor R10 can be set low (220 ohms in the example) (some signal discrimination circuits malfunction when an intermittent signal is applied if this resistance value is low) Capacitor C3 (47uF in the example) can be rapidly charged when an audio signal is applied.

This brings about the following effects. That is, in this embodiment, in areas where there is no signal when the caller puts down the handset, the device returns to the standby state when this no-signal state continues for approximately 7 seconds.

Therefore, if the caller interrupts the audio for more than 7 seconds, the device will return to the standby state and finish, but if the caller intends to continue speaking, the audio will be interrupted for nearly 7 seconds. If C3 can be quickly charged by the following voice, relay Y
This allows the device to continue operating without recovery.

Effect in the case of "no signal state" Second, the effect when the caller puts down the handset and the input terminal IN becomes a no signal state will be described.

The explanatory diagram after the time axis t10 in FIG. 3 can be applied to this, and the explanation is simple.

In other words, when there is no signal, Q5 turns ON as described above.
Therefore, the FF circuit 3 is cleared and the terminal 8 (Q output) becomes L level.

Therefore, Q6 is turned OFF, Q7 is turned ON, charging of C3 is stopped, and Q8 and Q9 are turned OFF after a predetermined time (approximately 7 seconds in this embodiment as described above) when the charge of C3 finishes discharging.
Then, relay Y returns to the station and returns the device to the standby state.

"When a busy tone is applied" The operation when the caller places the handset on the third caller and a busy tone is applied to the input terminal IN will be described.

In Figure 4, Figure G is the busy tone, Figure H is the collector voltage of Q3, Figure ■ is the collector voltage of Q5, and Figure J is the FF circuit 3.
The output of , K diagram is the collector voltage L diagram of Q7 is capacitor C
3 charging voltage.

Normally, the output terminal 8 (Q output) of the FF circuit 3 is inverted at the time points t12, t14 and t16 shown by the arrows in diagram H, but the time axis t12~t13, t14~ which is the no-signal part is inverted.
During t15, the FF circuit 3 is cleared as described above, so the output of the terminal 8 is naturally at the L level.

On the other hand, t12, t14 shown in diagram H. Q5 becomes O at a later time than the moment of switching from L level to H level at t16.
N (L level: If the operating point is set so that the second switching circuit 2 conducts at a lower level, it would be like this if the hysteresis and characteristics were the same) in an extremely short time. However, an H level output is generated from terminal 8 and relay Y cannot be restored.

However, in the present invention, the first and second switching circuits have hysteresis characteristics as shown in FIG.

That is, the second switching circuit 2, which is conductive at a low level, becomes non-conductive first due to the same human input signal.

This is because even if the input signal is interrupted, the smoothing capacitor C1. C
Since the charge is discharged according to a discharge curve determined by a constant of 2, this discharge characteristic is also utilized.

Therefore, t12, t14 in the figure. Q5 is turned on Δt after each time point t16.

As mentioned above, when Q5 turns ON, the FF circuit 3 is cleared, so it is cleared just before the trigger shown by the arrow in Figure H is applied, and the output of the FF circuit 3 remains at L level as shown in Figure J. Therefore, charging of C3 is stopped, and as shown in diagram L, the electric charge of C3, which has been charged to a predetermined level by the audio signal, is gradually discharged, and in the embodiment, about 7 seconds from the time when the application of the busy tone starts. Relay Y will be restored later.

Even if the above time difference △t is zero, that is, the first and second
Even if the switching circuit becomes non-conductive at the same time, there is no problem because the output of the FF circuit can continue to maintain the L level.

"When a dial sound is applied" Thirdly, the case where a dial sound (continuous sound) is applied will be described.

FIG. 5 is an explanatory diagram of the operation point.

It takes about 0.2 seconds after the caller hangs up the handset for the station to detect that the caller's telephone line is open and send a dial tone, and during this time there is no signal. state (before time axis t18).

As mentioned above, during this no-signal state, the FF circuit 3 is cleared and its output becomes L level.

Subsequently, a dial sound is applied from time axis t18, but O
As shown in the figure, even if the FF circuit 3 is preset after t18, no trigger is generated as shown in the N figure, so the FF circuit 3 maintains the above L level, and as is clear from the above, in this case Relay Y can be restored after about 7 seconds.

``When intermittent signals with different amplitudes are applied'' In some foreign stations, when the caller hangs up the handset, an intermittent signal as shown in diagram S in FIG. 6 is sent to the device.

Assume that the operating point V1 of the first switching circuit is set as shown in diagram S, for example.

However, it is necessary to set the operating points of these two switching circuits so that they are switched by the aforementioned audio signal.

Then, the collector voltage of Q3 becomes as shown in the T diagram, and the collector voltage of Q5 becomes as shown in the U diagram.As is clear from the above, the FF circuit 3 is about to be triggered at time axes t23 and t27, but each of the above The FF circuit is cleared before Δt from the point in time.

For example, between t24 and t25, this FF circuit is preset, but no trigger is generated during this period, so the output of the FF circuit is low as shown in diagram V.
The level can be maintained and relay Y can be restored after about 78 seconds as described above.

The low level signal part (e.g. t20 to t21) is the operating point V2
When switched, the same explanation as for the busy tone mentioned above applies.

The high level signal portion (e.g. t22 to t23) is the operating point V1
．． Assuming that there is no switching at V2 (although this is actually impossible, since the signal tone sent from the station is louder than the audio signal), it will be exactly the same as the no-signal condition described above. In either case, the relay Y can be restored after a predetermined period of time and the device can be returned to the standby state.

As described above, the first switching circuit (QN, Q2, Q3) and the second switching circuit (Q4, Q3), which have different operation levels,
Switching in which the operating point of Q5) is set so that it is switched by the audio signal, and the FF circuit 3 is cleared when the input signal is interrupted, and is switched at a high level when the input signal is interrupted. If the circuit has a hysteresis characteristic so that it becomes non-conductive first, triggers generated by various signal tones sent from the station will be added, and the output of the FF circuit will be inverted immediately before or at the same time. And disable this trigger F
The F circuit can be continuously maintained clear, and therefore the audio signal can be reliably distinguished from other signal tones, and the amplitude and frequency of the signal tones sent from the station, as well as the signal and non-signal components of intermittent signals, can be clearly distinguished. It has the characteristic that it is not affected by the period.

Note that the present invention is not limited to the embodiments described above and illustrated; for example, there are various types of FF circuits, but if a suitable inverter circuit is interposed, a negative edge trigger type can be used, and a switching circuit can also be used. An OP amplifier with appropriate hysteresis characteristics may be used, and various modifications can be made without changing the gist.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing hysteresis characteristics of a switching circuit.
Fig. 3 is an explanatory diagram of operating points for voice signals, Fig. 4 is an explanatory diagram of operating points for busy tone, Fig. 5 is an explanatory diagram of operating points for dial tone, and Fig. 6 is an explanatory diagram of operating points for intermittent signals with different amplitudes. It is a diagram. A.G. M and S diagrams are input signals, B. H. N. T diagram is Q3
Figures C, I, O, U are the collector voltage of Q5, Figures D, J, P, and V are the output of the FF circuit, E, K, Q,
W diagram shows the collector voltage of Q7, F, L. R,. X diagram is C3
charging voltage.

Claims (1)

[Scope of Claims] 1. A first switching circuit including a first rectifier circuit which inputs a voice signal, an intermittent tone such as a busy tone, a continuous tone such as a dial tone, and no signal, and inputs each of the above signals. a second switching circuit including a second rectifier circuit; a flip-flop circuit that uses the output of the first switching circuit as a clock input and the output of the second switching circuit as a preset and reset input; a timer circuit for controlling charging and discharging; means for making the second switching circuit conductive at an input level lower than that of the first switching circuit; and making the second switching circuit conductive in response to a change in the amplitude of the audio signal. means for repeating conduction and non-conduction of the first switching circuit during the switching process to maintain a closed circuit of the telephone line by continuing the operation of the timer circuit via the flip-flop circuit; A signal discrimination circuit in an answering machine, comprising means for stopping the operation of the timer circuit and releasing the closed circuit of the telephone line when the circuit becomes conductive and non-conductive almost simultaneously.