JPS59105742A - Detecting circuit of call signal - Google Patents

Abstract

PURPOSE:To prevent assuredly the misdetection of a dial impulse and together ringing by discriminating the difference of DC potential between telephone circuit terminals, and having a substantial detection only when the incoming possibility is recognized for a call signal. CONSTITUTION:A 16Hz signal detecting circuit 1 detects the call signal emerging between telephone circuit terminals L1 and L2 and sometimes detects a dial impulse as a call signal. The signal emerging between terminals L1 and L2 is also led to a rectifying circuit 2. The circuit 2 detects the absolute value of voltage (potential difference) between terminals L1 and L2. A DC voltage detecting circuit 3 monitors the level of rectification output and generates the detection output when said level reaches the value corresponding to the voltage (absolute value 48V) between terminals L1 and L2. An AND gate circuit 4 opens the gate only in a period when the detection output is delivered from the circuit 3 and delivers the detection output supplied from the circuit 1 to a ringing tone generating circuit as a detection output of the call signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ringing signal detection circuit that prevents problems such as resonance between telephones.

In the parent device of a tone ringer telephone or radio telephone device, a ring signal detection circuit detects the arrival of a ring signal from the exchange, and the detection output drives a separate ring circuit to generate a ring tone from a speaker, etc. I try to do that. FIG. 1 shows an example of the ejection signal detection circuit. That is, the detection circuit guides a ringing signal appearing on a pair of telephone line terminals to a bridge rectifier circuit via capacitors C1 and C2, and smoothes the signal rectified by this rectifier circuit with a circuit including capacitor C3. The level after smoothing is determined by the dirt circuit G, and a detection output is obtained.

However, when this building's ringing signal detection circuit is applied to a case where multiple telephones are connected in parallel to the telephone line terminal, the ringing signal detection circuit simply rectifies and smoothes the input signal to determine its level. , a dial impulse generated during a dial operation may be erroneously detected as a ringing signal, causing so-called resonance on other telephones.

In the case of the wireless telephone device d, there is not only a problem of resonance but also a problem of sending out calls unnecessarily.

This is because the dial-in/4' Luss is very similar to the ringing signal in box 1 pressure and generation pattern.

Therefore, in the past, the calling signal was a sine wave and the dial impulse was basically 1? Resonance has been prevented by focusing on the fact that the waveforms are waves and determining the form of these waveforms. However, since exchanges and telephone lines have complex impedances, dial impulses often suffer from waveform distortion due to transient responses and are no longer a rectangular wave. For this reason, dial impulses are sometimes erroneously detected as calling signals, and it has not been possible to completely prevent resonance.

The purpose is to provide a calling signal detection circuit that reliably prevents erroneous detection of dial impulses and does not cause resonance υ.

First, the present invention will be explained in detail with reference to FIG. The figure (,) shows the voltage waveform between the telephone line terminals at the time of transmission, and (b) shows the voltage waveform between the telephone line terminals at the time of arrival.

That is, the voltage between the telephone line terminals is, for example, -48V with one terminal as a reference during standby. In this state, offer the telephone connected to the above telephone line terminal, y
Then, as shown after time t1, the voltage between the telephone line terminals becomes approximately −10 V or less because the terminals are terminated with a DC voltage of several tens of ohms. Next, when dialing is performed (t2), a dial impulse appears between the terminals as shown in ■ in the figure, and the other subscriber responds to the call made by the exchange and goes off-hook.When the exchange completes the connection, after time ts As shown in , the voltage between the terminals becomes a positive voltage. Then, when the calling side goes on-hook to end the call, the terminals are opened and the voltage becomes +48V as shown after time t4 in the figure.When the exchange detects this on-hook and performs the call end processing, as shown after time t6. The voltage across the telephone line terminals returns to -48V, and the line goes into standby mode.

On the other hand, when there is an incoming call from the exchange in the standby state, the voltage across the telephone line terminals is as shown in the figure (time t6) -48
V changes to +48V, then 11″Y-out KM
No. O is sent out. This ringing signal is generally 16
A sine wave with a minimum of 45 V rms is transmitted for 1 second and then interrupted for 2 seconds. Then, when I respond to this call by going off-hook and the reminiscence becomes a m-story state,
Since the terminals are terminated with a DC voltage of several tens of ohms, the voltage becomes approximately -10V or less as shown from time t7 to time t8. After that, when the line goes on-hook, the terminals are opened, so the voltage returns to -48V, and the line enters the standby state.

Note that the polarity of the above voltage waveform will be reversed if the wiring of the telephone line to the exchange is reversed, but there is essentially no change.

By the way, if you compare the voltage between each terminal at the time of sending and receiving (J3), the voltage value at the time of receiving is always 48
In contrast, the voltage value just before the dial impulse pulse arrives is less than l1t6-tov. Therefore, it would be a good idea to determine each of these 1α pressure values and issue the alarm output only when the determined voltage is equal to or higher than the determination value (for example, between 10V and 48V). . The above is the basic principle of the present invention.

A first embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a block configuration diagram of the ejection signal detection circuit in the same embodiment, where Lr r L2 is each terminal of the telephone line, 7
rfi16HzQ detection (circuit shown.This 16
Hz signal detection circuit 1 connects telephone line terminal LHr L21
This circuit detects the ejection (No. 8) that appears at the start of the call, and is made up of, for example, the circuit shown in FIG.

Now, the signal appearing between the telephone line terminals and L2 is also led to the rectifier circuit 2. This rectifier circuit 2 consists of a diode bridge circuit, and has telephone line terminals L1, L.

This detects the absolute value of the voltage between the terminals (the difference in a). Therefore, no matter what direction the telephone line terminals are connected to the exchange, the voltage between the terminals can be detected reliably. A DC' voltage detection circuit 3 shown at 3 in the figure monitors the level of the rectified output and detects the voltage at the telephone line terminal L.
! It is determined whether the signal arriving at +L2 is a calling signal or a Guyar Innoculus signal. Then, the level of the rectified output is the terminal L1, L when the calling signal is tampered with.
A detection output is generated when a value corresponding to the voltage between the two (absolute value 48V) is reached.

FIG. 4 is a circuit diagram showing the configuration of this DC voltage detection circuit 3. The detection circuit guides the rectified output of the rectifier circuit 2 to the light emitting diode 32 via the current limiting resistor 31, and causes the light emitting diode 32 to emit light. The light emitting output of this light emitting diode 32 is received by a phototransistor 33 and converted into a voltage with a gain determined by a resistor 34. After this voltage is averaged by an integrating circuit 35, it is introduced into a comparator 36 and is applied to a reference power source 37. It is compared with the output voltage. Then, only when the average output level of the phototransistor 33 exceeds the reference voltage level, a detection output is generated because it is assumed that there is a possibility that a calling signal has arrived.

Furthermore, the nested circuit 4 shown in FIG.
f, f-) is open only during the period when the detection output is output from the tonnage pressure detection circuit 3, and at this time, the detection signal output from the 16Hz signal detection circuit 4 is used as the detection output of the ringing signal to generate a ringing tone (not shown). It outputs to the circuit.

Since it is a 4 pin configuration like this, ゛Telephone line terminal L1+L
When a calling signal arrives at the 16H1 signal detection circuit 1, a detection signal is generated from the 16H1 signal detection circuit 1, and since the absolute value of the DC level is as large as approximately 48V, a detection output is also generated from the DC voltage detection circuit 3. Therefore, the detection signal of the 16 Hz signal detection circuit 1 passes through the AND gate circuit 4 as it is, and as a result, a ringing tone generation circuit (not shown) is driven to generate a ringing tone.

On the other hand, telephone line terminal L! , when a dial impulse arrives at L2, even if the dial impulse is erroneously detected by the 16Hz signal detection circuit 1, the voltage level between terminals L1 and L2 when the dial impulse arrives is as shown in FIG. Since it is relatively small at less than 10V, is it DC? No detection output is generated from the iL pressure detection circuit 3. For this reason,
The antenna circuit 4 becomes non-conductive, and the above-mentioned 16
i(The detection signal of the z signal detection circuit 1 does not pass through, and as a result, the ejection sound generation circuit does not operate and no ringing sound is generated.

Further, at this time, the level judgment by the DC voltage detection circuit 3 is made during the off-hook period (between ti and t2 in FIG. 2) before the dial impulse actually arrives.
The AND gate circuit 4 is surely rendered non-conductive before the 16Hz 4M number generation circuit 1 generates the detection signal by the dial impulse. Therefore, resonance due to dial impulses is reliably prevented.

In this way, according to this clause 11, the telephone line terminal L!
The DC' voltage appearing at +1j2 is rectified and the rectified output level is judged by the DC' voltage detection circuit 3, and the AND/DART circuit 4 is controlled to dart based on this judgment output, so that false detection signals due to dial impulses are avoided. Even if it occurs, it can be reliably cut off, and as a result, resonance can be reliably prevented. - Also determines the DC voltage level appearing at telephone line terminals L1 and L2.
This is extremely simple compared to something that compares the waveforms of the signal and the call signal.
It has the advantage of being realized as a single unit.

FIG. 5 is a circuit configuration diagram showing a DC voltage detection circuit according to a second embodiment of the present invention, and the same parts as in FIG. 4 are given the same reference numerals. In the same figure, the difference in configuration from the previous embodiment (FIG. 4) is that a constant voltage element 38 is connected in series with the light emitting diode 32, so that the rectified output of the υ rectifier circuit 2 is The corresponding level (
For example, the light emitting diode 32 is driven to emit light only when the voltage exceeds 48 V, and the output voltage of the phototransistor 33 is averaged by the integrating circuit 35 and then output as a detection output via the inverter circuit 39. It is a point.

Since the time h'ti is like this, when an outflow force is introduced into the dial impulse, its level is smaller than that of the ringing signal and does not exceed the conduction voltage of the constant 1 red pressure element 38. Light emitting diode 32 and phototransistor 33 do not operate. Therefore, inverter circuit 3
9 does not output a detection output, and as a result, the AND gate circuit 4 becomes non-conductive and does not allow the detection signal 16 from the 16 Hz signal detection circuit 1 to pass through.

Therefore, according to the non-embodiment, the resonance p caused by the dial impulse can be reliably prevented as in the above-mentioned embodiment. Furthermore, compared to the case where the constant voltage element 38 is used, there is an advantage that the circuit configuration can be simplified.

On the other hand, FIG. 6 is a circuit diagram of a DC voltage detection circuit according to the third embodiment 11 of the present invention, in which the same parts as in FIG. 5 are given the same reference numerals. The detection circuit includes a constant voltage element 38, a light emitting diode 32, and a phototransistor 3.
For example, i
'Converting to TL level. And this conversion output As
The dart circuit 1184 is controlled by the inverter circuit 42, and the gate circuit 43 is controlled by the inverter circuit 42, and the clock signals BS and C8 from the clock oscillator 44, which are pass-controlled, are controlled to become the first and second clock signals. 2 counter circuits 45 and 45, respectively. These first and second counter circuits 45 and 46 count the clock signals BS and C8 that have passed through each of the dart circuits 41 and 43, and output an output every time the counted value reaches a constant. The flip-flop circuit 47 is set and reset by each of these outputs, and the output DS is directly outputted to the AND/DAT circuit 4 of FIG. 3 as a detection output.

With such a configuration, in the standby state, the conversion output As of H level is always output, so the first counter circuit 45 performs a counter-counting operation, and as a result, the flip-flop circuit 47 It maintains the set state and outputs an H level detection output.

Now, in this state, when the discharge signal arrives at time t6 and the conversion output AS goes to the L level as shown in FIG. The clock signal C8 is supplied to the second counter circuit 46 for results, and the second counter circuit 46 starts a counting operation. Further, the count value of the first counter circuit 45 is reset by the clock signal C8.

However, the repetition counting time of the second counter circuit 46 is set longer than the L level period of the conversion output A8. Therefore, the second counter circuit 46 does not output an output until the conversion output As returns to the H level, and the flip-flop circuit 47 is not reset. Therefore, the detection output DS is held at H level. After that, even if the conversion output As turns on and off according to the cycle of the calling signal,
The detection output DS holds the H level. Therefore, the third
The AND gate circuit 4 in the figure maintains a conductive state and operates at 16Hz.
The detection signal of the signal detection circuit 1 is supplied as is to the ringing tone generating circuit, and as a result, a ringing is performed.

On the other hand, if a dial operation is performed on another telephone, the off-hook operation at that time will be changed to the seventh
As shown in Figure (b), it becomes L level. Therefore, the second color/return circuit 46 starts counting operation instead of the first counter circuit 45. The period from off-hook to the start of dial operation is generally as long as about 1 second.

Therefore, if the counting period of the second counter circuit 46 is set to be shorter than the above period, the second counter circuit 46 will be at the L level before the dial operation is started. Emit output within the period. Therefore, the 7-lip floating circuit 47 is reset, and the detection output DS becomes L level as shown in FIG. 7(b). (hereafter)
The dial impulse arrives, which causes the conversion output As
Even if it changes between H level and L level as shown in FIG. 7(b), the counting period of the first counter circuit 45 is set to be longer than the H level period due to the dial impulse of the conversion output As. Therefore, the first counter circuit 45 does not generate an output.

Therefore, the flip-flop circuit 47 maintains the reset state, and the detection output DSf is maintained at the L level. Therefore, generation of a ringing tone due to the dial impulse is prevented.

In this way, in this embodiment, since the low level period immediately before the arrival of the dial impulse is detected,
It is possible to reliably bring the AND gate circuit 4 into a non-conductive state before the dial impulse pulse arrives, and as a result, malfunctions caused by the dial impulse can be almost completely prevented. In addition, the DC voltage obtained by the light emitting diode 32, phototransistor 33, etc. is converted to a TTL level by the inverter circuit 40, and the converted output is used for signal judgment, so most of the circuit is configured with digital circuits. This can facilitate circuit design and integration.

Further, FIG. 8 is a block diagram of a calling signal detection circuit in a fourth embodiment of the present invention.

In this figure, the same parts as those in FIG. 3 are given the same reference numerals and detailed explanations will be omitted.

This embodiment circuit reduces the power consumption of the circuit during steady operation, and also reduces the power consumption of the telephone line terminal L by the DC voltage detection circuit 3.
1. In order to prevent a decrease in DC resistance as seen from L2, unnecessary circuits are rendered inoperable during normal operation.

That is, the first switch 5 is provided between the rectifier circuit 2 and the DC voltage detection circuit 3, and the DC voltage detection circuit 3
A second switch 6 is provided in the power supply path to the switch 5, and each of these switches 5, 6 is turned on by a starting circuit 7.

This starting circuit 7 detects when the DC voltage between the telephone line terminals Ll and L2 drops from the normal state, that is, when off-hook occurs, and sends a signal to each of the switches 5 and 6 to turn on the switch. It happens.

On the other hand, the timer 8 generates a signal after a certain period of time has passed after the detection output of the DC voltage detection circuit 3 changes from L level to H level, and applies this signal to each switch 5.6 to open the switch. It's forcing me. The preset circuit 9 also provides an H level signal to the AND gate circuit 4 when the DC voltage detection circuit 3 is not operating.
This signal is used to set the circuit to a conductive state, and generates the above signal when there is no output from the starting circuit 7.

Incidentally, FIG. 9 is a diagram showing an example of the configuration of the starting circuit 70. In the same figure, a capacitor 71 and a resistor 7
2 constitutes a differentiating circuit, and this differentiating circuit allows the terminals L1. During L2, 9 edges of the tortoise pressure fall are detected. This falling edge is then supplied to a flip-flop circuit 75 via a photocoupler consisting of a light emitting diode 73 and a phototransistor 74, and sets the flip-flop circuit 75.

This flip-flop circuit 75 generates its set output as an activation signal. i fc, % The set state of the flip-flop circuit 75 is reset by the output of the timer 8.

With this configuration, the first and second switches 5 and 6 are each in an open state during standby, that is, during normal operation, so that 1! The communication line terminals Ll, L2 and the DC voltage detection circuit 3 are disconnected, and the power supply to the DC voltage detection circuit 3 is interrupted. Therefore, in this state, the DC voltage detection circuit 3 is in an inactive state and does not consume power, nor does the DC resistance as viewed from the telephone line terminal LllL2 decrease.

Now, in this state, telephone line terminal L11 is connected by off-hook.
When the voltage across L12 decreases, this is detected by the starting circuit 7 and a signal is output, which turns on each of the first and second switches 5 and 6. Therefore, when the DC voltage detection circuit 3 is in an operating state, the rectified output of the rectifier circuit 2 is introduced, its level is determined, and an L level detection output is output. As a result, the NO reset circuit 9 is reset, the AND gate circuit 4 becomes non-conductive, and the 16 Hz
Even if an erroneous detection signal due to a dial impulse is generated from the No. 4m detection circuit 1, its passage is blocked. Therefore, generation of ringing tone due to dial impulse is prevented.

On the other hand, when the DC voltage of the telephone line terminal L1 νL2 song returns to a high level due to on-hook and the detection output of the DC voltage detection circuit 3 becomes H level, the timer 8 starts counting operation and generates an output after a certain period of time has passed. do. As a result, the pot switches 5 and 6 are opened, thereby cutting off the power supply to the DC voltage detection circuit 3 and disconnecting the rectifier circuit 2 and the DC voltage detection circuit 3. At the same time, since the output of the starting circuit 7 is cut off, the υ preset circuit 9
td preset, and as a result, AND gate circuit 4 is maintained in a conductive state.

In addition, when a calling signal arrives, telephone line terminals L1 and L2
Since the voltage between them continues to be at a high level, the starting circuit 2 does not operate.

In this way, in this embodiment, the DC voltage detection circuit 3 is activated only when the dial is operated, and the rectification circuit 2 and the DC voltage detection circuit 3 are connected, so that during normal operation It is possible to put the DC voltage detection circuit 3 into an inoperable state and to disconnect it from the telephone line terminals LI and L2.

Therefore, it is possible to reduce power consumption and prevent a decrease in DC resistance, and it is possible to realize a circuit with a higher practicality of 4%.

As described in detail above, the present invention makes it possible to perform a substantial detection operation only when there is a possibility that a calling signal will arrive by determining the DC potential difference between the telephone line terminals. In other words, when there is no possibility that a paging signal will arrive, the detection operation is substantially prohibited.

Therefore, it is possible to provide a calling signal detection circuit that can reliably prevent erroneous detection of dial impulse pulses and can highly accurately prevent the occurrence of common ++Q signals.

Although a gate circuit is used in the example, the operation of the 916Hz signal detection circuit itself was controlled by the output of the DC voltage detection circuit! ', 16Hz (The opening/closing of the signal input path to the Ig signal detection circuit may be controlled.

[Brief explanation of drawings]

Figure 1 shows a 16-bit signal used as a conventional calling signal detection circuit.
Circuit configuration diagram of Hz signal detection circuit, Fig. 2(a), (
b) is a signal waveform diagram of a telephone line used to explain the principle of the present invention, FIG. 3 is a block diagram of a ring signal detection circuit in the first embodiment of the present invention, and FIG. 4 is a main part of the circuit. 5 is a circuit diagram showing a main part of the second embodiment of the present invention, FIG. 6 is a circuit diagram of a main part showing a third embodiment of the present invention, and FIG. 7 (8) , (b) is a signal waveform diagram used to explain the operation of the circuit, FIG. 8 is a block diagram of the call (Q component detection circuit) in the fourth embodiment of the present invention, and FIG. 9 is a diagram of the main components of the circuit. 1... 16 Hz 4'ii detection circuit, 2... Rectifier circuit, 3... DC voltage detection circuit, 4... AND gate circuit, 5... First switch, second switch, 7...starting circuit, 8...timer, 9...preset circuit, L,, L2...telephone line terminal. Applicant's agent Patent attorney Suzu Takehiko E Figure 3 1 114 Figure 51 6P!ij

Claims (2)

[Claims] (1) In a ringing signal detection circuit provided in at least one telephone among a plurality of telephones mutually connected in parallel to a telephone line terminal, a detection circuit main body that detects a ringing signal from a signal arriving at the telephone line terminal; DC voltage detection that detects the DC potential difference between telephone line terminals and controls so that when the detected value is within a preset value, a detection signal indicating that a discharge signal has been detected is not output from the detection circuit body to the outside. A calling signal detection circuit comprising: (2) The detection circuit main body includes a gate part, and the DC voltage detection part detects when the DC potential difference appearing between the telephone line terminals becomes less than a preset value and this state continues for a certain period of time. 2. The calling signal detection circuit according to claim 1, wherein a signal which does not pass the detection signal obtained by the above is outputted to the gate section.