JPS5912847Y2 - intercom - Google Patents

Description

[Detailed explanation of the idea] This invention relates to an intercom.

Normally, with an intercom, both stations are always on reception, and the person trying to talk presses the send button to call the other party, and then the other party takes turns talking.

However, one station may be kept in a transmitting state and used, for example, to monitor sleeping children or sick people, or to monitor telephone rings.

Conventionally, intercoms equipped with such a monitoring function have been used to enable one station to transmit by mechanical operation, but it is also possible to transmit from the other station to the other station. First, a person had to go to the other station to cancel the transmission, which was inconvenient.

The purpose of this invention is to provide an intercom that allows the other station to cancel the transmission state of one station.

Hereinafter, this invention will be explained based on one embodiment shown in the drawings.

゛In Fig. 1, numerals 2 and 4 are intercoms, each having the same structure.

Therefore, regarding the structure, only the interphone 2 will be explained, and the reference numerals attached to the corresponding elements of the interphone 2 with an a added at the end will be attached to each component of the interphone 4, and the explanation thereof will be omitted.

6 is a speaker that also serves as a microphone, 8 and 10 are audio amplification circuits, 1
2 is a buffer circuit, 14 is an FM modulation/demodulation circuit, 16 is a reception amplifier circuit, 18 is a transmission amplifier circuit, 20 is a transmission/reception separation circuit, and 21 is a transmission line.

Reference numeral 22 denotes a changeover switch for selectively connecting the microphone/speaker 6 to the audio amplification circuit 8 or the buffer circuit 12.

24□ is also a changeover switch for selectively connecting the modulation/demodulation circuit 14 to the audio amplification circuit 8.10.

Further, reference numeral 26 is a changeover switch for selectively connecting the modulation/demodulation circuit 14 to the reception amplifier circuit 16 or the transmission amplifier circuit 18.

28 is a transmission/reception switching control circuit, and when the talk button 30 or the call button 32 is pressed, the changeover switch 22, 24, 26
and controls the modulation/demodulation circuit 14.

Reference numeral 34 denotes a call signal generation circuit, which supplies an audible frequency call signal to the buffer circuit 12 when the call button 32 is pressed.

Reference numeral 36 denotes a switching signal generating circuit, which supplies a signal as shown in FIG. 2 to the switching control circuit 40 when the monitor button 38 is pressed.

42 is a detection circuit that detects the output of the demodulator when the modulation/demodulation circuit 14 operates as a demodulator and supplies it to the switching control circuit 40.

The switching control circuit 40 selects the changeover switches 22, 24, 26 based on the outputs of the switching signal generation circuit 36 and the detection circuit 42.
and controls the modulation/demodulation circuit 14.

Next, the operation of these intercoms 2 and 4 will be explained.

When the talk button 30, call button 32, and monitor button 38 of either intercom 2, 4 are not pressed, the microphone-cum-speaker 6, the audio amplification circuit 8, the modem circuit 14, the reception amplification circuit 16, and the transmission/reception separation circuit 20 are activated. The changeover switches 22, 24, 26 are switched so that the connection is made, and the modulation/demodulation circuit 14 is operating as a demodulator.

Therefore, the intercom 2 is in a receiving state.

The intercom 4 is also in a receiving state.

When the call button 32 is pressed in this state, the transmission/reception switching control circuit 28 switches the changeover switches 26, 24 and operates the modulation/demodulation circuit 14 as a modulator.

Therefore, the call signal generated by the call signal generation circuit is inputted to the modulation/demodulation circuit 14 via the buffer circuit 12 and the audio amplification circuit 10, where it is FM-modulated, further amplified by the transmission amplifier circuit 18, sent to the transmission/reception separation circuit 20, and then transmitted. It is supplied to the intercom 4 via line 21.

Since intercom 4 is in the receiving state, intercom 2
The call signal transmitted from the intercom 2 side is supplied to the microphone/speaker 6a, and the intercom 4 side can be called from the intercom 2 side.

When calling the intercom 2 side from the intercom 4 side, the call can be made in the same manner by pressing the call button 32a.

Note that when the user stops pressing the call button 32, the intercom 2 returns to the receiving state.

After this, when the talk button 30a is pressed, the transmission/reception switching control circuit 28a switches to the changeover switches 22a, 24a, 26.
Since a is used as a modulator, the microphone/speaker 6a, the buffer circuit 12a, the audio amplification circuit 10a, and the modulation/demodulation circuit 14 used as a modulator are switched.
a, the transmission amplification circuit 18a and the transmission/reception separation circuit 20a are connected and the intercom 4 enters the transmission state, and the content of the call made into the microphone/speaker 6a is transmitted to the intercom 2.
transmitted to the side.

Note that when the talk button 30a is released, the intercom 4 enters the receiving state.

The intercom 2 also enters the transmitting state by pressing the talk button 30.

Therefore, by alternately pressing the talk buttons 30.degree. 30a, a conversation can be made between the intercoms 2.4.

When using the intercom 4 as a monitor, the monitor button 32a may be pressed.

Then, the switching signal generating circuit 36a supplies a signal as shown in FIG. 2a to the switching control circuit 40a.

The switching control circuit 40a switches the changeover switches 22a and 24a to connect the microphone/speaker 6a and the buffer circuit 12a.
, the audio amplification circuit 10a is connected, and at the same time, at the signal portion A shown in FIG. Operate it and put it in the transmitting state.

Further, in part B, the changeover switch 24a is switched to connect the modulation/demodulation circuit 14a and the audio amplification circuit 8a, and to operate the modulation/demodulation circuit 14a as a demodulator.

Part B of this signal is shorter than part A (about a fraction of the time)
Moreover, since the period T of this signal is set to 100 to 500 msec, the clarity on the intercom 2 side is hardly degraded.

Therefore, the intercom 4 side can be monitored by the intercom 2 side.

When the call button 32 is pressed to cancel the monitor monitoring on the intercom 2 side, a call signal is transmitted to the intercom 4 side in the same way as when calling the intercom 4 side.

This call signal is demodulated by the modulation/demodulation circuit 14a when the modulation/demodulation circuit 14a is operating as a demodulator (at the time of part B in FIG. 2), and causes the detection circuit 42a to generate an output.

This output is supplied to the switching control circuit 40a, and the switching control circuit 40a connects the changeover switches 22a, 24a,
26a, the modulation/demodulation circuit 14a is operated as a demodulator, and the intercom 4 is placed in a receiving state.

Therefore, the monitor monitoring of the intercom 4 is stopped.

The same procedure is used when the intercom 2 side is monitored by the intercom 4 side, and when the monitor monitoring is canceled.

In this intercom, as mentioned above, the changeover switch 2
6a is alternately switched, and the modulation/demodulation circuit 14a is alternately operated as a modulator or a demodulator, so that monitoring can be stopped simply by pressing the call button 32 on the intercom 2 side, which is convenient.

Moreover, the changeover switches 22a and 24a are switched only when the detection circuit 42a detects a call signal.
No noise is generated.

Moreover, it is convenient because the conventional call signal for paging can be used as a signal for canceling the monitor monitoring.

In the above embodiment, the modulation and demodulation was FM modulation and demodulation, but AM
Modulation and demodulation can also be used.

Furthermore, although the modulator and demodulator are configured together in the modulation/demodulation circuit 14, they may be configured separately.

Furthermore, although the audio amplification circuits 8 and 10, the reception amplification circuit 16, and the transmission amplification circuit 18 are provided separately, they may also be configured to be shared.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an intercom implementing this invention, and FIG. 2 is a waveform diagram of a switching signal generating circuit. 2.4... Intercom, 6, 6a... Microphone/speaker, (8, 8a... Audio amplification circuit, 14.14
1... Modulation/demodulation circuit, 16.16 a... Receiving amplifier circuit) Receiving circuit, (10,101... Audio amplifier circuit, 1
4.141...Modulation/demodulation circuit, 18,181...Transmission amplifier circuit) Transmission circuit, 21...Transmission line, 22.228
．． 24.24 a, 26.26 a... Selector switch, 36.36 a... Switching signal generation circuit, 40.4
0 a...Switching control circuit, 42.421...Detection circuit.

Claims (1)

[Scope of utility model registration request] a microphone/speaker, a transmitting circuit, a receiving circuit, a first changeover switch for selectively connecting the microphone/speaker to the input side of the transmitting circuit or the output side of the receiving circuit; In two intercoms each having a second changeover switch for switching and connecting a common transmission line to the input side of the receiving circuit, each of the above two intercoms is provided with a second changeover switch for switching and connecting a common transmission line to the input side of the receiving circuit, and a remote control is provided to the receiving circuit of the other intercom. A circuit that supplies a signal,
The input side of the receiving circuit and the output side of the transmitting circuit of the intercom to which it belongs are connected to the second A changeover switch of the intercom to which it belongs, respectively, to the common transmission line at a predetermined period. a control circuit that alternately switches and connects the intercom to which it belongs and maintains the first changeover switch of the intercom to which it belongs in a state where the microphone-cum-speaker of the intercom to which it belongs is connected to the input side of the transmission circuit of the intercom to which it belongs; Each of the above two intercoms is provided with a receiving circuit, and detects the remote control signal from the other party's intercom, and switches the first and second changeover switches of the interphone to which it belongs, respectively. An intercom comprising the microphone-cum-speaker, the receiving circuit, and the common transmission line connected in series.