JPS6239584B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a telephone hook-off and ringing signal detection circuit, and more particularly to a detection circuit that outputs a hook-off detection output and a ringing signal detection output.

Conventionally, various methods have been proposed in which a single detection element is used to distinguish between a telephone ringing signal and a dial impulse signal, and only the detection output of the regular ringing signal is extracted. , the frequency f ₀ of the calling signal from the central office, and 10PPS
The frequency of the dial impulse signal f ₁ and
The relationship between the frequency f ₂ of the 200PPS dial impulse signal is f ₁ < f ₀ < f ₂ , and the maximum value of the continuous signal transmission time of the 20PPS dial impulse signal is approximately 1/2 of the transmission time of the ringing signal. We are proposing a method of identification using the fact that it is twice as large.

However, all of these conventional methods simply extract the detection output of the calling signal, and in order to send hook-off information to an attached device in the home such as a facsimile receiving device of a telephone, it is necessary to
A separate hook-off detection circuit was required.

In view of the above points, the present invention was made to solve such problems, and its purpose is to share one detection element and have an extremely simple configuration.
It is an object of the present invention to provide a hook-off and ringing signal detection circuit for a telephone that reliably outputs a hook-off detection output and a ringing signal detection output without malfunctioning with a dial impulse signal of 10PPS or 20PPS.

In order to achieve such an objective, the present invention
The relationship between the frequency f ₀ of the calling signal from the central office, the frequency f ₁ of the 10PPS dial impulse signal, and the frequency f ₂ of the 20PPS dial impulse signal is 2f ₀ >
f ₂ > f ₁ , and while the loop current of the telephone is cut off during the pause time of the ringing signal, the loop current always flows continuously for a certain period of time after hook-off, even when dialing. This fact is used for identification and detection. Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a circuit diagram showing an embodiment of a telephone hook-off and ringing signal detection circuit according to the present invention. In the figure, TEL is the telephone, DET is the bidirectional current detection circuit that detects the bidirectional current flowing in the direct current loop of the telephone TFL, INT is the integrator circuit that integrates the output of the bidirectional current detection circuit DET, and TIM ₁ is the integrator circuit INT. Repeats charging and discharging using the integral output of
The first timer circuit TIM 2 sends out a ringing signal detection output when the level exceeds a predetermined level, and the first timer circuit TIM ₂ sends out a hook-off detection output when the output of the bidirectional current detection circuit DET continues for more than a predetermined time. This is the second timer circuit that clears the timer circuit TIM ₁ of .

The bidirectional current detection circuit DET is a light emitting element.
Photocoupler consisting of Pd ₁ and photodetector Pt ₁ Photocoupler PC ₁ consisting of light emitting element Pd ₂ and photodetector Pt ₂
PC ₂ , one of the common connection points of the light emitting elements Pd ₁ and Pd ₂ is connected to the input terminal L ₁ , the other is connected to the input terminal L ₁ ' via the resistor R ₂ , and the light receiving element The collector common connection point of Pt ₁ and Pt ₂ is connected to the positive side of the power supply Vcc. VR and R ₁ are a varistor and a resistor connected in parallel between input terminals L ₁ and L ₁ '. Also, the integrator circuit INT is connected to R ₆ and this resistance
The resistor _R6 is connected to the transistor _Q1 whose base is connected to the emitter common connection point _of the light receiving elements _Pt1 and _Pt2 through _the resistor _R3 . connected to the collector,
A connection point A between the resistor R ₆ and the capacitor C ₁ is connected to the collector of the transistor Q ₁ via the resistor R ₇ and the diode D ₁ in series. And the transistor
The collector of Q ₁ is connected to the positive side of the power supply Vcc through resistor R ₅ , the emitter is grounded, and the base is connected to the resistor
Grounded via _R4 .

The first timer circuit TIM ₁ includes a transistor Q ₂ whose base is connected to a connection point between a resistor R ₈ and a resistor R ₉ that divide the integrated output of the integrating circuit INT;
A resistor _R10 , a diode _D2 , and a capacitor _C2 are connected in series with the positive side of the power supply Vcc and the ground side to form a charging circuit, and a programmable unit that becomes conductive when the voltage across the capacitor _C2 reaches a certain level. Junction transistor (hereinafter referred to as
The base is connected to the connection point of Q ₃ (referred to as PUT) and resistors R ₁₃ and R ₁₄ connected in series to the cathode side of this PUT Q ₃ , and the collector is connected to the call signal TELCAL.
It consists of a transistor _Q4 which serves as the output terminal. And the anode side of PUT Q ₃ is connected to capacitor C ₂ via resistor R ₁₂ and also to resistor R ₁₁ connected in parallel to capacitor C ₂ ,
The gate terminal that controls the conduction voltage of PUT Q ₃ has a
It is configured such that a voltage divided by a resistor _R15 and a resistor _R16 connected in series between the positive side of the power supply Vcc and the ground side is supplied. Further, the collector of the transistor _Q4 is connected to the positive side of the power supply Vcc via a resistor _R17 , and the emitter is grounded.

The second timer circuit TIM ₂ is connected to the transistor Q ₁
A transistor _Q5 whose base is connected to the collector of the transistor Q5 through a resistor _R18 , and a resistor connected in series between the positive side of the power supply Vcc and the ground side to form a charging circuit.
R ₁₉ , R ₂₀ and capacitor C ₃ and this capacitor C ₃
becomes conductive when the voltage across it reaches a certain level
It consists of a transistor Q ₇ whose base is connected to the connection point of PUT Q 6 and resistors R ₂₁ and R ₂₂ connected in series to _the cathode side of this PUT Q ₆ , and whose collector serves as a hook-off HOKOF output terminal. The anode side of PUT Q ₆ is connected to the connection point C of resistor R ₂₀ and capacitor C ₃ , and the gate terminal that controls the conduction voltage of PUT Q ₆ is connected in series between the positive side of the power supply Vcc and the ground side. Connected resistor R ₂₃ and resistor R ₂₄
The circuit is configured to supply a voltage divided by. In addition, the collector of the transistor Q ₇ is connected to the positive side of the power supply Vcc via a resistor R ₂₅ , and is also connected to the capacitor C ₂ of the first timer circuit TIM ₁ via a diode D ₃ and a resistor R ₁₂ in series. and the emitter of transistor _Q7 is grounded.

Next, the operation of the embodiment shown in FIG. 1 will be explained with reference to FIGS. 2 and 3. FIG. 2 shows a time chart when a 16 Hz calling signal is received, and FIG. 3 shows a time chart from hook-off to dialing. In Fig. 2, IN is a signal frequency f ₀ that is intermittently sent from the telephone office with a repetition of 1 second for continuous signal transmission time and 2 seconds for signal pause time applied to input terminals L ₁ and L ₁ '. Shows a 16Hz ringing signal. In Figure 3, IN is the input signal when the dial "0" is sent, the dial impulse signal of 10 Hz, 10 PPS is 1 second, and the dial impulse signal of 20 Hz, 20 PPS is 0.5 seconds, when the dial time D is the longest (0 finger rotation). It shows. P indicates dial pause time, and this dial pause time P is 550ms or more at 10PPS and 550ms or more at 20PPS.
It is 450ms or more.

In other words, the relationship between the frequency f ₀ of the ringing signal, the frequency f ₁ of the 10PPS dial impulse signal, and the frequency f ₂ of the 20PPS dial impulse signal is 2f ₀ > f ₂
> f ₁ .

First, a case will be described in which a calling signal (16Hz sine wave AC signal) is applied to the input. in this case,
The second terminal is connected from the telephone office to the input terminals L ₁ and L ₁ ' shown in Figure 1.
As shown in Figure IN, a 16 Hz ringing signal is sent for 1 second and then paused for 2 seconds. This calling signal is then detected by the bidirectional current detection circuit DET,
By the output thereof, the transistor _Q1 is turned on and off as shown in FIG. 2 _Q1 . At the same time, the output of the bidirectional current detection circuit DET is changed to the integrator circuit INT.
The potential at point A changes as shown in FIG. 2A. The output of the integrating circuit INT is input to the first time circuit _TIM1 , and the transistor _Q2 is turned off during the signal transmission time of 1 second and turned on during the signal pause time of 2 seconds, as shown in FIG. ₂ Q2. When transistor Q ₂ turns off, capacitor C ₂ becomes a resistor
It is charged by the power supply Vcc via _R10 and diode _D2 , and when this charging voltage reaches a certain level, ie, the gate voltage, PUT _Q3 becomes conductive. PUT
When Q ₃ conducts, capacitor C ₂ connects with resistor R ₁₂
It is discharged through the PUT Q ₃ anode cathode and resistors R ₁₃ and R ₁₄ , and the potential at point B changes as shown in FIG. 2B. Then, when the signal rest time of the calling signal arrives, the transistor Q ₂ shifts to the on state, and when the signal sending time arrives, the transistor Q ₂ turns off, and the capacitor C ₂ starts to be charged by the resistor R ₁₀ and the diode D ₂ . be done. The capacitor C ₂ is further charged according to the time constant determined by the resistor R ₁₀ , and the charging voltage increases to the resistor R 10.
When the gate voltage divided by R ₁₅ and R ₁₆ is reached,
PUT Q ₃ conducts. Here, the charging time constant of the first timer circuit TIM ₁ is set to such a time constant that the PUT Q ₃ is turned on even at the second arrival when the calling signal is received. Also, the time constant of the integrator circuit INT is the first in the call signal.
The time constant is set so that the transistor Q ₂ of the timer circuit TIM ₁ does not turn on, and the dial impulse signal repeatedly turns on and off.

Now, when PUT Q ₃ conducts, transistor Q ₄
is turned on, and a call signal detection signal as shown in FIG. 2 TELCAL is obtained from the output terminal TELCAL.

On the other hand, the collector output of transistor _Q1 is the second
The signal is supplied to the base of the transistor _Q5 of the timer circuit _TIM2 , and the transistor _Q5 turns on and off as shown in FIG. 2 _Q5 . When the transistor _Q5 turns off, the capacitor _C3 is charged by the power supply Vcc via the resistors _R19 and _R20 , but the charging time constant is set to a time constant that does not turn off the PUT _Q6 during the sending period of the ringing signal. PUT
Q ₆ is not conductive. Therefore, transistor Q ₇
does not shift to the on state, and the hook-off detection output
HOKOF is not sent.

Next, the operation during dialing when 10PPS and 20PPS dial impulse signals are added to the input will be explained. In this case, the input terminal shown in Figure 1
Pulse signals are supplied to L ₁ and L ₁ ', as shown in Figure 3 IN, with a maximum continuous impulse signal transmission time (when dialing "0") of 1 second at 10 PPS and 0.5 seconds at 20 PPS. . P indicates dial pause time. The photocoupler PC ₁ is also operated by this dial pulse, and the transistor Q ₁ is controlled on/off in response to the pulse signal as shown in FIG. 3 Q ₁ . The output of this transistor _Q1 is input to the integrating circuit INT and integrated, and the potential at point A changes as shown in FIG. 3A. Here, as mentioned above, the charging time constant of the integrating circuit INT is set to a time constant that repeatedly turns on and off in the dial impulse signal, so the transistor Q ₂ of the first time circuit TIM ₁ corresponds to it. Then, as shown in Fig. 3, _Q2 , it operates on and off. And when transistor Q ₂ is turned off, capacitor C ₂ is powered through resistor R ₁₀ and diode D ₂
It is charged by Vcc, and the potential at point B changes as shown in FIG. 3B.

On the other hand, the collector output of transistor _Q1 is the second
The signal is input to the base of the transistor _Q5 of the timer circuit _TIM2 , and the transistor _Q5 operates on and off as shown in FIG. 3 _Q5 . When transistor Q ₅ is turned off, capacitor C ₃ is charged by the power supply Vcc via resistors R ₁₉ and R ₂₀ , and when transistor Q ₅ is turned on, capacitor C ₃ is charged by resistor R ₂₀ and transistor
Discharged through the collector-emitter of _Q5 , C
The potential at the point once drops to ₀ V as shown in Figure 3C. Then, when the dial pause time P comes,
Transistor _Q5 remains off, so C
The potential at the point increases as shown in Figure 3C, and PUT
The conduction voltage of Q ₆ is reached and PUT Q ₆ conducts. Due to this conduction of PUT Q ₆ , transistor Q ₇ is turned on, and a hook-off detection output can be obtained as shown in FIG. 3 HOKOF.

At this time, transistor _Q7 is turned on, so the third
As shown in Figure A, the first timer circuit is forced to
TIM ₁ capacitor C ₂ resistor R ₁₂ , diode
D ₃ discharges through the collector-emitter of transistor Q ₇ and resets the timer operation. Here, in receiving the dial impulse signal,
The PUT of the second timer circuit TIM ₂ must be turned on before the PUT Q ₃ of the first timer circuit TIM ₁ is turned on.
A second timer circuit so that _Q6 turns on.
The charging time constant of TIM ₂ is set smaller than the charging time constant of the first timer circuit TIM ₁ . Therefore,
When the dial impulse signal is applied to the input terminal, PUT Q ₃ of the first timer circuit TIM ₁ does not operate and the output of the output terminal does not appear.

The present invention has been described above using an example in which the time from hook-off to dialing is extremely short; however, if the time from dialing is long, the hook-off detection output can be obtained immediately after hook-off. Even in the worst case, hook-off can be detected at the initial pause time of the first and second finger rolls. Also, the dial impulse signal is
No malfunctions at either 10PPS or 20PPS.

As explained above, according to the present invention, 10PPS
It is possible to reliably detect the dial impulse signal of 20PPS without malfunction, and with a simple circuit configuration.
The practical effects are extremely large.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of a telephone hook-off and ringing signal detection circuit according to the present invention;
2 and 3 are time charts in the embodiment of FIG. 1 to explain the operation of FIG. 1. DET...Bidirectional current detection circuit, INT...Integrator circuit, TIM ₁ , TIM ₂ ...Timer circuit.

Claims (1)

[Claims] 1. A bidirectional current detection circuit that detects the bidirectional current flowing in the direct current loop of the telephone and sends intermittent detection outputs for dial pulses and ringing signals, respectively, and integrates the output of this bidirectional current detection circuit to detect the intermittent dial pulse. There is an integrator circuit that sends out an intermittent output for the detection output and continuous output for the intermittent detection output of the calling signal and the DC loop detection output, and performs a timekeeping operation using the output of this integrator circuit. A first timer circuit that does not time up when the sum of the intermittent output corresponding to the maximum dial pulse train and the DC loop detection output for a certain period of time required for hook-off detection, but times up when the sum of two or more continuous outputs corresponding to the ringing signal Then, a timekeeping operation is performed by the detection output of the bidirectional current detection circuit, and the time-up does not occur with the intermittent detection output corresponding to the dial pulse and the ringing signal, and the time-up occurs when the DC loop detection output continues for a certain period of time or more. a second timer circuit that resets the timer circuit of the first timer circuit;
A hook-off and ringing signal detection circuit for a telephone set, characterized in that the time-up output of the second timer circuit is used as a ringing signal detection output, and the time-up output of the second timer circuit is used as a hook-off detection output.