JPH0834524B2 - 2-wire simultaneous call intercom device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a two-wire simultaneous call intercom.

(Prior Art) Conventionally, when transmitting and receiving using a two-wire type transmission line, a hybrid coil has been used to separate transmission / reception signals. However, in the case of the two-wire system using the hybrid coil, there is a possibility that howling may occur when the transmission signal sneaks into the reception circuit and the impedance of the transmission line changes. In addition, the call having the higher level is prioritized by comparing the sending level and the receiving level. Therefore, if the transmission level is always higher than the reception level due to noise or the like, reception cannot be satisfied.

(Problems to be Solved by the Invention) An object of the present invention is to provide a device that does not cause howling and is controlled so as to be forcibly set to a reception state.

(Means for Solving Problems) The present invention has the following configuration in order to achieve the object.

(1) The variable loss circuit of the receiving system is inserted when a variable loss circuit is individually inserted into the transmitting system and the receiving system coupled to the hybrid transformer, and when the case where the transmitting level exceeds a predetermined value is detected from the transmitting system. And a second level detecting circuit for lowering the transmission level by controlling the variable loss circuit of the transmission system when detecting a case where the reception level exceeds a predetermined value from the reception system. And a first electronic switch inserted in the transmitting system and a control unit for controlling the operation of the first electronic switch so as to periodically disconnect the transmitting system, forcibly receiving. A two-line simultaneous call intercom device that puts you in standby.

(2) The variable loss circuit of the receiving system is inserted when the variable loss circuit is individually inserted into the transmitting system and the receiving system coupled to the hybrid transformer, and when the case where the transmitting level is higher than a predetermined value is detected from the transmitting system. And a second level detecting circuit for lowering the transmission level by controlling the variable loss circuit of the transmission system when detecting a case where the reception level exceeds a predetermined value from the reception system. Of the hybrid transformer, the receiving end of the modulation / demodulation device is connected to the reception system of the hybrid transformer, the transmission end of the modulation / demodulation device is connected to the transmission system of the hybrid transformer, and 1
Of the electronic switch and the control unit for controlling the operation of the first electronic switch so as to periodically disconnect the transmission system, forcibly put in the reception standby state, and data transmission using the modulator / demodulator is performed. 2-wire simultaneous transmission / reception intercom device to start.

(Embodiment) FIG. 1 is a system diagram of an intercom apparatus according to an embodiment of the present invention. 1 is a two-wire intercom device, 10 is a microphone, 11 is a transmission amplifier, 12 is an analog switch, 13 is a control unit that controls the operation of the analog switch 12, 14 is a variable loss circuit that controls the attenuation of the transmission signal, 15 Is a transmission level detection circuit, 16 is a transmission amplifier, 17 is a 2-wire to 4-wire conversion hybrid transformer, 18 is a reception amplifier, 19 is a variable loss circuit for controlling the attenuation of reception signals, 20 is a reception level detection circuit, 21 Is a receiver amplifier, 22 is a speaker, 2 is an elevator car, 3 is a telephone device having an automatic dialing function, 4 is a telephone line, 5 is a telephone exchange of a central office, and 6 is a telephone of a monitoring center.

An example in which the intercom device 1 according to an embodiment of the invention is attached to the elevator car 2 and a call is made with the telephone of the monitoring center via a telephone line will be described below.

First, when the detection circuit 27 receives the emergency notification signal from the elevator car 2, the control circuit 13 operates the telephone device 3 and calls the telephone 6 of the monitoring center by its automatic dialing. After that, a call is started between the intercom apparatus 1 and the telephone 6 via a telephone line. The transmission signal from the intercom device 1 is transmitted to the telephone 6 by the following route.

Microphone 10-amplifier 11-analog switch 12-variable loss circuit 14-amplifier 16-hybrid transformer 17-telephone device 3
Telephone line 4-exchanger 5-telephone line 4-telephone 6.

The received signal of the intercom 1 is transmitted by the following route.

Telephone 6-Switch 5-Telephone equipment 3-Hybrid transformer 17-Amplifier 18-Variable loss circuit 19-Amplifier 21-Speaker
twenty two.

Note that when there is only one signal for transmission or reception, the attenuation amount of the variable loss circuit 14 or 19 becomes zero. As described above, the transmission / reception of the interphone device 1 is alternately performed.

This intercom system is hands-free and allows simultaneous calls. In addition, a hybrid transformer 17 is used to convert 2 lines to 4 lines. For this reason, if left as it is, the transmitted signal may sneak into the receiving circuit and cause howling.

In order to prevent howling, this circuit controls the variable loss circuit 19 of the receiving circuit when the level detecting circuit 15 detects a transmitting level equal to or higher than a predetermined value when the transmitting signal is input to the microphone 10. Make the loss big.

Therefore, in this state, a part of the transmission signal passes through the hybrid transformer 17 and flows into the reception circuit, but is not output to the speaker because the loss amount of the reception circuit is large.
Even if there is an input signal from the telephone 6, this variable loss circuit
By passing through 19, the input signal is greatly attenuated and the output of the speaker 22 becomes small. At this time, the input to the level detection circuit 20 of the receiving circuit also becomes low level, and the attenuation amount of the variable loss circuit 14 of the transmitting circuit is set to zero. As described above, the output of the speaker 22 is kept low by the variable loss circuit 19 while the call is first started from the microphone of the hands-free intercom apparatus 1 and continued. If there is no input signal to both the intercom unit 1 and the telephone set 6, the input signal does not reach the level detection circuits 15 and 20 of the transmitter circuit and receiver circuit, and the variable loss circuits 14 and 19 of the transmitter circuit and receiver circuit are The amount of attenuation is 0.

Next, when there is an input to the telephone 6, an output is generated to the speaker 2 of the intercom apparatus 1 by the above-mentioned route. If this reception signal is higher than the reception level preset by the level detection circuit 20 of the reception circuit, the amount of attenuation of the variable loss circuit 14 of the transmission circuit is made large. Therefore, even if the transmission signal is sent from the microphone 10, it is greatly attenuated by the variable loss circuit 14 and does not reach the detection output from the level detection circuit 15.

As described above, a normal call is made between the intercom apparatus 1 and the telephone 6 via the telephone line 4. Further, the present invention may have a configuration of an intercom and a base unit (telephone) using only two lines instead of via the exchange 5 and the telephone line 4.

Next, an elevator emergency notification device, which is partially omitted, will be described as an application example.

In the circuit of FIG. 1, when an abnormal state occurs in the elevator car 2, a call is started between the intercom device 1 and the telephone 6 of the monitoring center.

At this time, if the inside of the elevator car 2 becomes panicked, a transmission signal (noise) is sent to the microphone 10 of the intercom system 1.
Is entered without interruption. The level detection circuit 15 detects this transmission signal and the variable loss circuit 19 of the reception circuit
Is maintained in a state of large attenuation. If this happens, the person in the elevator car 2 will not be contacted by the surveillance center and will be even more anxious.

Therefore, in this circuit, the control unit 13 uses the analog switch 12
The intercom apparatus 1 disconnects the transmission circuit for a time required for the intercom apparatus 1 to switch from the transmission state to the reception state. As shown in Fig. 2 as an example, the state is 0.1
The analog switch 12 is made non-conductive only for seconds.
When the control unit 13 makes the analog switch 12 non-conductive, the transmission signal is not input to the level detection circuit 15 of the transmission circuit, and thus the attenuation of the variable loss circuit 20 of the reception circuit is set to 0. During this time, if there is an instruction signal from the telephone 6 of the monitoring center, it is output to the speaker 22 of the intercom apparatus 1 and transmitted to the person in the elevator car 2. Further, while the instruction signal continues, the level detection circuit 20 of the transmitter circuit increases the attenuation amount of the loss circuit 14 of the transmitter circuit, so that the hybrid transformer 17 has a low level even if the analog switch 12 is conducting. Only the level transmission signal reaches.

Therefore, a telephone call can be made between the intercom apparatus and the telephone.

FIG. 3 is a system diagram in which the intercom device and the function of transmitting data on the monitoring center side are added to FIG. A modulation / demodulation device (hereinafter referred to as a modem) 61 and a monitor control device 62 are connected in parallel with the telephone 6. A modem 26 is connected to the transmitting system and the receiving system of the intercom system 1. The analog switches 23 and 24 are for disconnecting the microphone 10 and the speaker 22, and the analog switch 25 is for disconnecting or connecting a modulation / demodulation device (hereinafter referred to as a modem) 26 from the transmission system. A detection circuit 27 that detects an abnormality or the like other than the abnormality notification signal is connected to the control circuit 13. 28 is a howling prevention circuit.

Next, in the middle of a call between the intercom device and the monitoring center side, when data transmission is started from the monitoring center side to control the elevator car side, data transmission request data is sent to the intercom device 1 by the following route.

Monitor control device 62-modem 61-telephone line 4-switching machine 5-telephone line 4-telephone device 3-hybrid transformer 17-amplifier 18-modem 26-control unit 13. When the control unit 13 receives the data transmission request data, the analog switches 23 and 24 are made non-conductive to disconnect the microphone 10 and the speaker 22, and the analog switch 25 is made conductive to connect the transmission terminal of the modem 26 to the transmission circuit of the intercom apparatus 1. To do. Therefore, data can be transmitted and received between the monitoring control device 62 of the monitoring center and the control unit 13 of the intercom device 1.

However, during a call between the intercom device 1 and the telephone 6 of the monitoring center, if a signal that the modem 26 detects is generated from the microphone 10 or the amplifier 11, data transmission from the monitoring control device 62 of the monitoring center. It may happen that the request data is not correctly detected by the control unit 13 via the modem 26.

Therefore, under the control of the control unit 13, the analog switch 12 is made non-conductive for 0.1 seconds at a cycle of 1 second as an example. Therefore, the output from the microphone 10 is interrupted for 0.1 second, and during this time, the control unit 13 can detect the data transmission request data from the monitoring control device 62 and start the above-described data transmission.
Further, it is also possible to end the data transmission and start the call under the control of the monitor control device 62.

(Effects of the Invention) As described above, the present invention can prevent howling and forcibly set the reception standby state periodically.

[Brief description of drawings]

FIG. 1 is a system diagram of an intercom system and others according to an embodiment of the present invention. FIG. 2 is a diagram showing the operating state of the analog switch. FIG. 3 is a system diagram of an intercom system and other components according to another embodiment of the present invention. 1 ... Intercom device, 15,20 ... Detection circuit, 14,19 ...
… Variable loss circuit, 17 …… Hybrid transformer, 12,25
...... Analog switch, 13 ...... Control section, 26 …… Modem.

Claims (2)

[Claims] 1. A variable reception circuit is inserted into each of a transmitting system and a receiving system coupled to a hybrid transformer, and when the case where the transmitting level exceeds a predetermined value is detected from the transmitting system, the receiving system is changed. The first level detection circuit for controlling the loss circuit to lower the receiving level, and the variable loss circuit of the transmitting system to control the transmitting level when the receiving system detects that the receiving level is higher than a predetermined value. A first electronic switch including a second level detection circuit and further inserted in the transmission system;
A two-wire simultaneous call intercom device characterized by comprising a control unit for controlling the operation of the electronic switch to periodically disconnect the transmission system and forcibly putting it in a reception standby state. 2. A variable loss circuit is individually inserted into a transmitting system and a receiving system coupled to a hybrid transformer, and when the case where the transmitting level is equal to or higher than a predetermined value is detected from the transmitting system, the receiving system is changed. The first level detection circuit for controlling the loss circuit to lower the receiving level, and the variable loss circuit of the transmitting system to control the transmitting level when the receiving system detects that the receiving level is higher than a predetermined value. A second level detection circuit,
A receiving end of a modulation / demodulation device is connected to a reception system of the hybrid transformer, a transmission end of the modulation / demodulation device is connected to a transmission system of the hybrid transformer, and a first electronic switch inserted into the transmission system; A control unit for controlling the operation of the first electronic switch so as to periodically disconnect the transmission system is provided to forcibly enter a reception standby state, and data transmission using the modulator / demodulator is started. A 2-wire simultaneous transmission / reception intercom system.