JPH0230623B2 - DENWAKI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a telephone that transmits and receives voice signals to and from a partner station using carrier waves.

Conventionally, as a telephone of this type, there is a carrier wave type intercom for confidential communication and amplification, which uses a power line as a signal line and is schematically shown in FIG.

In the figure, reference numeral 1 denotes a microphone attached to one end of a handset (transceiver), and this microphone 1 is connected to a power line (not shown) via an FM modulation circuit 2, a transmission circuit 3, and a power plug 4. .

The transmitting circuit 3 is activated when the handset is removed from the intercom body or when the output of the control circuit 5 described later is supplied, and is activated when the handset is locked to the body or when the output of the control circuit 5 disappears. The device is configured to be in an activated state.

The power plug 4 is connected via a receiving circuit 6 and a demodulating circuit 7 to a speaker 8 attached to the other end of the handset.

Furthermore, the receiving circuit 6 is connected to a carrier wave detection circuit 9 that generates a detection signal when detecting a carrier wave transmitted by the transmission circuit 3 of the partner station.

The carrier wave detection circuit 9 is connected to the control circuit 5 via the integrating circuit 10, and this control circuit 5 is connected to the integrating circuit 1.
The transmitting circuit 3 is operated while the output of 0 is being supplied.

In the thus configured confidential speech amplification intercom, the two intercoms A and B are used as a set, and the transmitting circuit 3a of the intercom A transmits audio signals using a carrier wave with a frequency of ₁ so that simultaneous two-way communication can be carried out. The transmitting and receiving circuits 6 are configured to receive audio signals transmitted using a carrier wave with a frequency of ₂ , and the intercom B receives a voice signal transmitted using a carrier wave with a frequency of 2, and a transmitting circuit 3b with a carrier wave with a frequency of ₂ , and a receiving circuit 5d with a carrier wave with a frequency of ₁ . It is configured to send or receive audio signals, and when making a confidential call, the handsets of both parties are lifted from the intercom body, and when making a loudspeaker call, the calling party picks up the handset, The called party makes a call with the handset locked.

However, since a power line containing a lot of noise is used as a signal line, if noise of frequency ₁ or ₂ is input from the power line and the control circuit 5a or 5b malfunctions, the transmitting circuit 3a or 3b becomes activated and this As a result, the other transmitting circuit 3b or 3a also enters the operating state, and this state continues even after the noise disappears, and the speaker 8
Noise was sometimes emitted from a and 8b.

Furthermore, at this time, since the handsets of both intercoms A and B were locked to the main body, the degree of acoustic coupling between the microphones 1a and 1b and the speakers 8a and 8b was high, which could cause howling.

In order to prevent this kind of thing, the time constant of the integrating circuit 10 should be made sufficiently large compared to the noise width, but the integrating circuit 10 with a large time constant is Since it has an output for a certain period of time, the speakers 8a and 8b remain active even after the call ends.
There were times when a noise was emitted.

According to the present invention, the detection signal of the carrier wave detection circuit 9 described above is easily generated by mistake due to noise in the power line when the carrier wave from the other station is not supplied, and conversely, when the carrier wave from the other station is not supplied, the detection signal is easily generated by mistake. Taking advantage of the fact that the detection signal is less likely to be interrupted by noise when the detection signal is being generated,
By increasing the time constant of the integrating circuit when there is a detection signal and decreasing it when there is no detection signal, it is possible to provide a carrier-wave type intercom for both private speech and amplification that does not generate howling or emit noise. That is.

Hereinafter, the present invention will be explained based on a pair of carrier wave intercoms A and B as an embodiment.

A pair of intercoms A and B are configured such that the transmitting frequency of intercom A and the receiving frequency of intercom B are ₁ (KHz), and the transmitting frequency of intercom B and the receiving frequency of intercom A are ₂ (KHz). Since they are otherwise the same, the structure of only one intercom A will be explained, and both intercoms will be distinguished by adding a and b to the end of the reference numeral.

In FIG. 2, 20a is a microphone, which is attached to one end of the handset.
a is connected to a power line (not shown) via an amplifier 22a, an attenuator 24a, an audio switch 26a, an FM modulation circuit 28a, a transmission circuit 30a, a coupling circuit 32a and a power plug 34a.

The coupling circuit 32a also includes a band filter 36a,
It is connected to a speaker 46a attached to the other end of the handset via an FM demodulation circuit 38a, an audio switch 40a, an amplifier circuit 42a, and an attenuator 44a.

Further, 50a is a ringing tone generation circuit, and the output of this ringing tone generation circuit 50a is transmitted to audio switches 54a and 56 controlled by the output of the tone color adding circuit 52a.
It is connected to the input side of the FM modulation circuit 28a and the input side of the amplifier circuit 42a via a.

Further, 60a is a control circuit, and this control circuit 60a
A carrier wave detection circuit 6 is connected to the output side of the frequency band filter 36a and detects the presence or absence of a carrier wave transmitted from the other party's intercom.
4a, connected to the output side of the FM demodulation circuit 38a 40
The timbre adding device 52a, the audio switches 26a, 40a, the transmitting circuit 30a and A control signal is sent to each output terminal 80a, 82 to a tone generating circuit 78a which sends an output to the input side of the FM modulation circuit 28a via a resistor 76a.
a, 84a, 86a.

These carrier wave detection circuit 64a and tone detection circuit 66a are connected to input terminals 72a and 7 when there is no signal.
4a is set to high level, and input terminals 72a and 74a are set to low level when a signal is detected.

Furthermore, by switching the switch 62a, the attenuation amounts of the attenuators 44a, 24a are changed to be suitable for a loudspeaker call and a confidential call, respectively.

Next, FIG. 3 shows a detailed circuit diagram of the control circuit 60a. In the figure, 100a and 102a are a first integrating circuit and a second integrating circuit, and these integrating circuits 1
00a and 102a are resistors 106a and 108a whose one ends are connected to the Vcc terminal 104a, resistors 110a and 112a whose one ends are connected to the other ends of these resistors 106a and 108a, and a diode 114.
a, 116a, and capacitors 118a, 120a whose one end is connected to the other end of these parallel circuits and whose other end is grounded, and the input terminal 72a is connected to the resistor 106a and the resistor 110.
The input terminal 74a is connected to the resistor 10 at the connection point with a.
It is connected to the connection point between 8a and resistor 112a.

When the first integrating circuit 100a receives a falling signal from the input terminal 72a, the capacitor 118a
Since the accumulated charge is gradually discharged through the resistor 110a, the output terminal voltage of the first integrating circuit 100a, that is, the terminal voltage of the capacitor 118a is
After the falling signal is input, the capacitor 118
After a time t ₁ (seconds) determined by the capacitance of a and the resistance value of the resistor 110a, the voltage becomes equal to or less than the threshold value of the inverter 122a, which will be described later.

Similarly, in the second integration circuit 102a, t ₂ (seconds) after the falling signal is input to the input terminal 74a,
The terminal voltage of capacitor 120a becomes below the threshold of inverter 150a, which will be described later.

Conversely, when a rising signal is input to the input terminal 72a, the capacitor 118a is connected to the diode 11.
4a, the output voltage of the first integrating circuit 100a exceeds the threshold of the inverter 122a in a short time t ₃ (seconds).

Similarly, when a rising signal is input to input terminal 74a, the output voltage of second integrating circuit 102a exceeds the threshold of inverter 150a at time t ₄ (seconds).

Further _{, the first} integrating circuit _100a and _the second integrating circuit 102a are arranged so _{that the} capacitors _118a , 12
0a capacitance and resistance 110a, 112a, 106
The resistance values of a and 108a are set.

The output terminal of the first integrating circuit 100a, that is, the connection point between the resistor 110a and the capacitor 118a is connected to the inverter 122a and to one input terminal of the inverting input AND circuit 124a,
The output terminal of this inverting input AND circuit 124a is connected to the output terminal 82a via a resistor 126a. Further, the output terminal of the inverter 122a is connected to one input terminal of the NAND circuit 128a.

The output terminal of the NAND circuit 128a is the differential circuit 1
30a is connected to one end of a capacitor 132a, and the other end of this capacitor 132a is connected to a resistor 1.
34a to the Vcc terminal 104a.

The output terminal of the differentiating circuit 130a, that is, the other end of the capacitor 132a, is connected to the cathode side of a diode 138a constituting the OR circuit 136a, and the anode side is connected to the Vcc terminal 104a via a resistor 140a.

Further, the output terminal of the OR circuit 136a, that is, the anode side of the diode 138a is connected to the inverting input RS.
It is connected to the input terminal of flip-flop 142a. Inverting input RS flip-flop 142
a is two inverting input OR circuits 144a, 146a
The Q output terminal is the output terminal 84.
A also has an output terminal as an inverting input AND circuit 124
It is connected to the other input terminal of a.

The output terminal of the second integrating circuit 102a, that is, the connection point between the resistor 112a and the capacitor 120a is connected to the inverter 150a.
The output terminal of 50a is connected to the other input terminal of the NAND circuit 128a and the differential circuit 130a.
It is connected to a differentiating circuit 152a having the same configuration as .

The output terminal of the differentiating circuit 152a is connected to the OR circuit 1.
The output terminal of the OR circuit 153a, that is, the anode side of the diode 154a, is connected to the input terminal of the inverting input RS flip-flop 142a.

The hook switch portion 62a includes a switch 156a that is opened by removing the handset;
The resistor 158a has one end connected to one terminal of the switch 156a. The other end of this switch 156a is grounded, and the resistor 1
The other end of 58a is connected to Vcc terminal 104a. Furthermore, one end of the switch 156a is the input terminal 7.
0a and attenuators 24a and 44a. This input terminal 70a is a direct output terminal 86
a and is also connected to the anode side of the diode 168a.

Further, 170a and 172a are differentiating circuits 130a
The input terminal of the differentiating circuit 170a is directly connected to the input terminal 70a, and the differentiating circuit 172 has the same configuration as the differentiating circuit.
The input terminal of a is connected to the input terminal 70a via an inverter 174a.

The output terminal of the differentiating circuit 172a is connected to the OR circuit 1.
The anode side of the diode 176a is connected to the anode side of the diode 138a.

The output terminal of the differentiating circuit 170a is connected to the OR circuit 1.
The anode side of the diode 178a is connected to the anode side of the diode 154a, and is also connected to the Vcc terminal 104a via a resistor 180a.

Further, 200a is an RS flip-flop using NOR circuits 202a and 204a, and the S input terminal of this flip-flop 200a is grounded through a resistor 206a, and connected to the Q of the inverting input RS flip-flop 142a through a capacitor 208a.
connected to the output terminal.

Further, the R input terminal of the RS flip-flop 200a is connected to the cathode side of the diode 168a and to the cathode side of the diode 210a. The anode side of this diode 210a is connected to the Q output terminal of the inverting input RS flip-flop 142a.

The Q output terminal of the RS flip-flop 200a is
It is connected to the output terminal 80a, and the output terminal is connected to the resistor 2.
12a, and is grounded via a large capacitor 220a. Furthermore, the cathode side of a diode 222a is connected to the output terminal, and the anode side of this diode 222a is connected to the output terminal 82a.

Further, the connection point between the resistor 212a and the capacitor 220a is connected to one terminal of a switch 224a that constitutes a confidential speech amplification switch 223a, and is also connected to a resistor 226a, an inverter 228a, and a resistor 224a.
30a to the R input terminal of the RS flip-flop 200a, and the other terminal of the switch 224a is connected to the Vcc terminal 104a.

This switch 224a is closed in conjunction with a tone changeover switch 240a to be described later, and when closed, this intercom A operates as a confidential intercom A, and when opened, it operates as a loudspeaker intercom A.

The tone color adding device 52a includes an inverter 242a, a NAND circuit 244a, and resistors 246a, 248a, 2
50a, capacitors 252a, 254a, and a diode 256a.
When 40a is closed, capacitor 254a is short-circuited and the oscillation frequency changes.

Two intercoms A configured in this way,
B are used by being connected to the power lines in the same transformer.

Handsets are now installed on both intercoms A and B, and the confidential loudspeaker switch 223a, 22
3b has been switched to the amplification side.

In this state, the inverted input RS flip-flops 142a and 142b of both intercoms A and B
Q output terminal and RS flip-flop 200a,
The Q output terminal of RS flip-flop 200b becomes low level, and the Q output terminal of inverting input RS flip-flop 142a, 142b and RS flip-flop 200a,
The output terminal 200b is at a high level, and the capacitors 220a and 220b are in a state where charges are accumulated.

Therefore, both intercoms A and B have input terminals 70a, 70b and output terminals 80a, 80b, 82a, 82b, 84a, 84, except that input terminals 74a, 74b, 72a, 72b are at high level.
b, 86a, 86b are at low level, transmitting circuits 30a, 30b, tone generating circuits 78a, 78b
None of them work. In this state, even if noise with frequencies ₁ and ₂ is input from the power line and the outputs of the carrier wave detection circuits 64a and 64b change from high level to low level, the period during which the outputs are at this low level is very short, and the capacitor 118a , 118b and resistor 1
Since the discharge time constants of inverters 10a and 110b are made long, the outputs of integrator circuits 100a and 100b do not drop to the threshold values of inverters 122a and 122b. Therefore, as mentioned above, intercoms A and B
transmitting circuits 30a, 30b, tone transmitting circuit 78
a and 78b do not malfunction.

Next, set the intercom A handset at time T _1.
When the switch 1 of the hook switch part 62a is removed,
56a switches, and the input terminal 70a changes from low level to high level. When the input terminal 70a becomes high level, the output terminal 86a also becomes high level, the tone generation circuit 78a is activated, and the differentiation circuit 172 is activated.
a sends a low level pulse to the OR circuit 136a. This low level pulse is applied to the inverting input RS flip-flop 142a, causing the Q output terminal to go high and the output terminal to go low.

When the Q output terminal of the inverting input RS flip-flop 142a becomes high level, the output terminal 84a also becomes high level, the transmitting circuit 30a is activated, and the intercom A is FM modulated by the 40 Hz tone signal sent out by the tone transmitting circuit 78a. Modulated wave ₁ (K
Hz) to the power line.

This modulated wave ₁ (KHz) passes through a coupling circuit 32b of interphone B and a band filter 36b, and is supplied to a carrier detection circuit 64b, and is also supplied to a tone detection circuit 66b via an FM demodulation circuit 38b.

The carrier wave detection circuit 64b and the tone detection circuit 66b of the interphone B detect the carrier wave and the tone signal, respectively, and output the signals to the input terminals 72b and 7 at time _T1 .
4b is set to low level.

When the input terminals 72b and 74b become low level, the first integrating circuit 100b switches to the second integrating circuit 100b after _t1 seconds from time _T1 .
The output terminals of the integrating circuits 102b become low level after t ₂ seconds, and the output terminal of the NAND circuit 128b changes to low level after t ₂ seconds. As a result, the differentiating circuit 130b supplies a low level pulse to the input terminal of the inverting input RS flip-flop 142b via the OR circuit 136b.

This low level pulse causes the inverting input RS flip-flop 142b to be inverted, the Q output terminal to be at a high level, the output terminal to be at a low level, and the output terminal 84b to be at a high level, thereby activating the FM transmitting circuit 30b.

At the same time, both input terminals of the inverting input AND circuit 124b become low level, and the inverting input AND circuit 1
At this time, whether the output terminal of 24b becomes high level,
As will be described later, since the Q output terminal of the RS flip-flop 200b is at a low level, the output terminal 82b remains at a low level.

When the Q output terminal of the inverting input RS flip-flop 142b goes high, the capacitor 208
b, RS flip-flop 2 by resistor 206b
A high level pulse is applied to the S input terminal of RS flip-flop 200b, causing the Q output terminal of RS flip-flop 200b to be at a low level and the Q output terminal, that is, the output terminal 80b, to be at a high level.

When the output terminal 80b becomes high level, the timbre addition circuit 52b is activated, and the audio switches 54b and 56b are activated.
The ringing tone generation circuit 50b is intermittently conductive.
The ringing tone generated by FM is supplied to the amplifier circuit 42b and the FM modulation circuit 28b.

The ringing tone supplied to the amplifier circuit 42b is emitted from the speaker 46b via the attenuator 44b, and the ringing tone supplied to the FM modulation circuit 28b is
The signal is sent from the activated FM transmitting circuit 30b to the intercom A via the coupling circuit 32b, the power plug 34b, and the power line.

When the FM modulation circuit 28b of the interphone B is activated, the carrier wave detection circuit 64a of the interphone A is activated, and the input terminal 72a is set to a low level.

When the output of the first integrating circuit 100a becomes a low level t ₁ second after the input terminal 72a changes to a low level, both input terminals of the inverting input AND circuit 124a become a low level, so the output terminal 82a becomes a high level. level, the audio switch circuits 26a, 40a
is made conductive, and the ringing tone sent from intercom B is emitted from speaker 46a.

Further, in intercom B, when the output terminal of the RS flip-flop 200b changes to a low level, the charge accumulated in the capacitor 220b is gradually discharged by the resistor 212b, and the terminal voltage of the capacitor 220b changes to the low level.
Inverter 228 T ₀ seconds after 0b is reversed
b is below the threshold value, and as a result, inverter 2
28b becomes a high level, the RS flip-flop 200b is inverted again, the Q output terminal is set to a low level, and the output terminal is set to a high level, and the timbre addition circuit 52b is stopped, and the output terminal 82a is set to a high level and the intercom B is output. voice switch 2
6b and 40b are brought into conduction.

Therefore, the audio switches 26a, 26b, 40a, 40b of both intercoms A and B are in a conductive state, and the transmitting circuits 30a and 30b are in an operating state, so that intercoms A and B can communicate with each other.

Next, while talking to each other on intercoms A and B, the time
If the handset of intercom B is removed at _T2 , switch 156b of intercom B is switched, and input terminal 70b and output terminal 86b go to high level. At the same time, a low level pulse is applied to the input terminal of the inverting input RS flip-flop 142b;
42b is not inverted.

When the output terminal 86b becomes high level, the tone transmission circuit 78b is activated, and the intercom B sends out to the intercom A a carrier wave modulated with a 40 Hz tone signal.

Interphone A detects this tone signal with tone detection circuit 66a, and sets input terminal 74a to a low level.

When the input terminal 74a becomes low level, a low level pulse is also applied to the S input terminal of the inverting input RS flip-flop 142b of the intercom A;
is not inverted and the Q output terminal remains at high level and the output terminal remains at low level.

Next, at time _T3 , when the handset of intercom B is locked to the main body, switch 156b changes, input terminal 70b changes to low level, and output terminal 8
6b also changes to a low level.

As a result, the tone generating circuit 78b is stopped and a low level pulse is generated at the output of the differentiating circuit 170b, and this low level pulse is transmitted to the inverting input RS.
The signal is supplied to the input terminal of the flip-flop 142b, the output terminal changes to high level, the Q output terminal changes to low level, the output terminals 82b and 84b become low level, stopping the operation of the transmitting circuit 30b, and the audio switch 26b, 40b is brought into a discontinued state.

When the transmission circuit 30b of the intercom B stops operating, the carrier wave detection circuit 64 of the intercom A stops operating.
b. Both tone detection circuits 66a have no output, and input terminals 72a and 74a are set to high level at time _T3 .

As a result, after t ₃ seconds from time T ₃ , the first integration circuit 1
The output terminal 00a becomes high level, one input terminal of the inverting input AND circuit 124a becomes high level, the output terminal 82a becomes low level, and the audio switches 26a and 40a are turned off.

Furthermore, after t ₄ seconds from time T ₃ , the second integration circuit 10
Since the output terminal of 2a also becomes high level, a low level pulse is generated at the output of the differentiating circuit 152a, and this low level pulse is supplied to the input terminal of the inverting input RS flip-flop 142a via the OR circuit 153a. .

This causes the inverting input RS flip-flop 14
2a is inverted and the Q output terminal becomes low level, so the transmitting circuit 30a connected to the output terminal 84a
also stops working.

Furthermore, _t3 seconds after the transmission circuit 30a of intercom A stops operating, the output terminal of the first integrating circuit 100b of intercom B goes to a high level, and after _t4 seconds, the output terminal of the second integrating circuit 102b goes to high level. becomes a high level, and intercom B returns to its initial state.

Further, by locking the handset to the main body using the intercom A and closing the switch 156a, the intercom A also returns to its original state. As mentioned above, the time required for the integration circuits 100a and 100b to return to the high level is t ₃ seconds later, which is shorter than the time t ₁ required for the integration circuits 100a and 100b to return from the high level to the low level.
It immediately enters the standby state.

In addition, intercom B's confidential loudspeaker switch 2
23b is the confidential side, that is, switches 224b, 24
If both 0b and 0b are closed, the tone signal from the intercom A causes the RS flip-flop 20 to be closed.
When the Q output terminal of 0b goes high, it will not invert until the handset of intercom B is picked up, and the ring tone will be emitted until the handset is picked up.

Also, the tone of the ringtone at this time is switch 240.
Since capacitor 254b is shorted by b,
The tone is different from the tone of the ringtone when the secret amplification switch 223b is switched to the amplification side.

As described above, according to the present invention, the time constant of the integrating circuit that integrates the carrier wave detection signal is set to be large when the carrier wave detection signal is generated and small when the carrier wave detection signal is lost. Therefore, even if noise with the same frequency as the carrier wave frequency of the transmitting circuit is generated and the above detection signal is generated, the time constant of the integrating circuit is large at that time, so the output of the integrating circuit is set to a value that activates the transmitting circuit. This prevents the transmission circuit from malfunctioning. Therefore, in the standby state, the transmitting circuit will not malfunction and send the carrier wave to the other station, and the other station will also operate and both will be in the transmitting state, causing howling. Further, when the detection signal disappears, the transmitting circuit can be quickly stopped because the time constant of the integrating circuit is small. Therefore, the sound output from the noise speaker ends immediately after the call ends.

In addition to the embodiments described above, the present invention may be implemented in a wireless telephone capable of simultaneous two-way communication.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional carrier-wave type intercom for private speech and amplification, Fig. 2 is a block diagram of a carrier-wave type intercom for secret speech and amplification which is an embodiment of the present invention, and Fig. 3 is a block diagram of a control circuit in the same embodiment. The detailed circuit diagram and FIG. 4 are operation timing diagrams of the same embodiment. 20a...Microphone, 28a...FM modulation circuit, 30a...Transmission circuit, 38a...FM demodulation circuit,
46a...Speaker, 60a...Control circuit, 100a
...first integration circuit, 102a...second integration circuit.

Claims (1)

[Claims] 1. A transmitting circuit that transmits a carrier wave modulated by an audio signal input from a microphone to a partner station, a receiving circuit that demodulates the modulated carrier wave transmitted from the partner station and outputs it from a speaker, and the modulated carrier wave is supplied to this receiving circuit. a carrier wave detection circuit that generates a detection signal when the detection signal is detected; an integration circuit that integrates the detection signal; and a carrier wave detection circuit that activates the transmission circuit when the output signal of the integration circuit is supplied or a transmission start signal is supplied. , a telephone set comprising a control circuit that deactivates the transmitting circuit when the transmitting start signal or the output signal of the integrating circuit disappears, the time constant of the integrating circuit is set to be large when the detecting signal is generated; A telephone set that is set to become smaller when the signal is lost.