JPH0383443A - Switching type interphone - Google Patents

Abstract

PURPOSE:To automatically switch and connect one of plural inhouse equipments to one entrance equipment by a switch with simple configuration by providing a relay for switching to be a part of a direct current to be supplied from the inhouse equipments to the entrance equipment as an operating power source. CONSTITUTION:A monostable relay is used as a relay Ry for switching and the common terminal of contacts S1 and S2 is connected to an entrance equipment G. When a second inhouse equipment J2 is not operated, the direct current of a transmission line connected to the inhouse equipment J2 is low. Accordingly, for the relay Ry being this current as the operating power source, the common terminal is connected to a normally closed terminal and the entrance equipment G is connected to a first inhouse equipment J1. Next, when a monitoring switch is operated or a hand set is picked up in the inhouse equipment J2, the supply of the direct current is started from the inhouse equipment J2. An all-wave rectifier DB is connected to the transmission line connected to the inhouse equipment J2 and by the rectifying output, a transistor Q1 is turned ON. Then, the direct current flows to the relay Ry for switching and the common terminal is switched and connected from the normally closed terminal to a normally opened terminal. Afterwards, the entrance equipment G is connected with the inhouse equipment J2.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a switching type intercom,
This device is suitable for communication between an entrance device installed at the entrance and a plurality of residential unit devices installed in a dwelling unit.

[Prior Art] FIG. 3 shows a schematic configuration of a conventional intercom system with a television. This system is constructed by combining a dwelling unit J with a monitor TV 1 installed inside the dwelling unit and an entrance unit G with a TV camera 21 installed at the entrance, both of which are connected using a dedicated cable such as a coaxial cable. They are connected by a transmission line l. Direct current is supplied to the entrance device G as an operating power source from the dwelling unit J, and a video signal is transmitted from the entrance device G to the dwelling unit J. Also, audio signals are transmitted bidirectionally.

FIG. 4 shows the frequency division state of the signal transmitted via the transmission line 1 in this system.

As shown in the figure, the FM modulated wave of the audio signal sent from the door device G to the door device J is transmitted at the first carrier frequency f, and the FM modulated wave of the audio signal sent from the door device J to the door device G. is transmitted at the second carrier frequency 12. The carrier frequencies f and f2 of the audio signals are set to frequencies higher than the video signal frequency band of the television camera transmitted in baseband, thereby preventing interference. Note that direct current is superimposed as the operating power source for the entrance device G, and these are multiplexed and transmitted via a dedicated transmission line l.

A more specific configuration of the intercom system is shown in FIGS. 5(a) and 5(b) and will be described below. Judoki J is
A power superimposing circuit 8 for supplying power to the entrance device G, a calling signal detection circuit 19 for detecting a calling signal transmitted in response to the operation of the calling switch 24 of the entrance device G, and a calling signal detecting circuit 19 for detecting a calling signal transmitted from the calling speaker 3 when a calling signal is detected. A ringing tone generation circuit 20 that sounds a ringing tone, an audio modulation circuit 17 that modulates an audio signal with FM,
An audio demodulation circuit 13 that demodulates the FM modulated signal sent out from the entrance device G to extract an audio signal, a handset 2 that includes a microphone and a speaker for phone calls, and audio amplifiers 14 and 15 that constitute the phone call circuit that includes the handset 2, and the side a sound prevention circuit 6; a video signal output circuit 11 that collects the video signal sent from the entrance device G and outputs it to the monitor TV 1;
The FM modulated signal outputted from the audio modulation circuit 17 is inputted via the bandpass filter 18, and the FM modulated signal outputted from the entrance device G is inputted to the bandpass filter 1.
2 to the audio demodulation circuit 13, the video signal sent from the entrance device G to the video signal output circuit 11 through the video filter 10, and the supply voltage of the power superimposing circuit 8 to the entrance device G. A balanced input/output circuit 9 for transmission is provided. The audio modulation circuit 17 is configured to perform FM modulation on the transmitted audio signal from the handset 2 and send it out to the transmission line l through the balanced input/output circuit 9, and the audio demodulation circuit 13
The configuration is such that the FM modulated signal from the balanced input/output circuit 9 is demodulated and the voice of the entrance device G is output from the handset 2. Further, the video signal transmitted from the entrance device G is outputted to the monitor television 1 after being amplified by the video signal output circuit 11 via the balanced input/output circuit 9 and the video filter 10. A transmission line short-circuit protection circuit 6 and an open detection circuit 7 are added to the power supply superimposition circuit 8. Moreover, when the monitor switch 4 is operated, the control circuit 5 is operated, the power superimposing circuit 8 is operated, and power is supplied to the entrance device G.

On the other hand, the entrance device G includes an audio demodulation circuit 38 that demodulates the FM modulated signal sent from the housing device J and outputs an audio signal.
Audio modulation circuit 40 that modulates the audio signal from the microphone 23
, a calling signal generating circuit 43 that generates a calling signal in response to the operation of the calling switch 24, an operating state determining circuit 42 that determines the operating state and can generate a calling signal if the call is not in progress, and a voice modulation circuit An FM modulated signal outputted from the circuit 40 via the bandpass filter 41, a calling signal outputted from the calling signal generation circuit 43, and the television camera 2.
1 inputs a video signal outputted through a video filter 30 and a video signal output circuit 31 and sends out a multiplexed transmission signal to a transmission line 1, and outputs an FM modulated signal to an audio demodulation circuit 38 via a bandpass filter 37. A balanced input/output circuit 32, a non-polarizing circuit 33 for non-polarizing the connection between the transmission line l and the doorway unit G, and a balanced input/output circuit from the modulated signal sent from the housing unit J via the transmission line g. Power supply separation circuit 3 for separating the power supply of the entrance device G via the circuit 32
4. The power supply voltage separated by the power supply separation circuit 34 is used as a camera power source and a circuit power source via a power switch circuit 35 and a shunt regulator 36. The audio modulation circuit 40 modulates the audio signal input from the microphone 23 and amplified by the audio amplifier 26 and sends it to the housing unit J via the balanced input/output circuit 32. It is configured to demodulate the FM modulated signal from the output circuit 32, amplify it in the audio amplifier 39, and output audio from the speaker 22.

With the above configuration, the dwelling device J can monitor the situation on the side of the entrance device G by video, and can also communicate with the door device G when it opens.

[Problems to be Solved by the Invention] In the above-mentioned conventional example, for example, if two dwelling units can be switched and connected to one entrance unit, and it is configured so that either unit can communicate with the video monitor. It's convenient. For that purpose, one entrance unit and one of multiple housing units are required.
It is necessary to provide a switch to switch between the two. In order to control this switch, a method can be considered that detects a signal sent from an entrance switch or a dwelling unit and switches the transmission line.

However, this method requires a signal demodulation circuit to detect the signal, making the configuration complicated, and there are also problems in that a power source necessary for circuit operation must be secured. On the other hand, manual control may be considered as another method for controlling the switching device, but with this method, you have to go to the location where the switching device is installed in order to switch the transmission line, and you have to go to the location where the switching device is installed. The problem is that the benefits of being able to monitor and talk are diminished.

The present invention has been made in view of these points, and its purpose is to use a switch with a simple configuration,
To provide a switching type intercom capable of automatically switching and connecting one of a plurality of dwelling units to one entrance unit.

[Means for Solving the Problems] In the present invention, in order to solve the above problems, the first
A pair of transmissions as shown! ! The entrance device G and the dwelling unit J1 are connected through e, and the direct current that serves as the operating power source for the entrance device G is supplied from the dwelling unit J to the transmission line l, and at least the audio signal is transmitted via the transmission line l. In an intercom that performs multiple transmission, one entrance device G and multiple dwelling unit devices J, , J
2, and the switch is equipped with a switching relay Ry that uses part of the DC current supplied from the dwelling unit J2 to the entrance unit G as an operating power source. This is a characteristic feature.

Here, the switching relay Ry has a common terminal connected to the entrance unit G, a normally closed terminal connected to the first housing unit J, a normally open terminal connected to the second housing unit J2, and a normally closed terminal connected to the second housing unit J2. If we use a monostable relay that is driven so that the common terminal is switched to the normally open terminal by the DC current supplied from the transmission line connected to the housing unit J2, we can realize the switch K with a very simple configuration. be able to.

Note that, as shown in FIG. 2, a bistable relay may be used.

[Example 1 FIG. 1 is a circuit diagram of a first embodiment of the present invention.

In this embodiment, a monostable relay is used as the switching relay RY. Sl and S2 are switching relays Ry
It is a contact point and has a common terminal, a normally closed terminal, and a normally open terminal. The common terminal is connected to the entrance device G, and the normally closed terminal is connected to the first terminal. , the normally open terminal is connected to the second housing unit J.
Connected to 2.

When the second dwelling unit J2 is not operating, the DC voltage of the transmission line connected to the second dwelling unit I2 is low, so the switching relay R uses this as the operating power source.

The common terminal is connected to the normally closed terminal.

Therefore, the entrance device G is connected to the first dwelling device J. In this state, the operation is similar to that of the conventional example shown in FIG.

Next, when the monitor switch 4 is operated or the handset 2 is raised on the second dwelling unit J2, the second dwelling unit J2
Supply of DC current starts from.

A full wave rectifier DB is installed on the transmission line connected to the second housing unit J2.
is connected, and its rectified output causes bias resistance R
A base current flows through transistor Q through R1 to R3, and transistor Q is turned on. As a result, a direct current flows through the switching relay Ry, and the common terminal is switched from a normally closed terminal to a normally open terminal. Therefore, the entrance device G is connected to the second dwelling unit J2.

Next, when the second dwelling unit J2 finishes the call operation, the second
Since the DC voltage of the transmission line connected to the housing unit J2 becomes low, no DC current flows through the switching relay Ry, and the common terminal is switched from the normally open terminal to the normally closed terminal. Thereby, the entrance device G is connected to the first dwelling unit J again.

Note that the back electromotive force generated when the direct current flowing through the switching relay Ry is interrupted is prevented by the diode D1.

As described above, in this embodiment, the switching relay Ry
Since a monostable relay is used as the switching device and the switching operation is performed by the DC voltage on the transmission line connected to the second dwelling unit J2, the configuration of the switching device can be greatly simplified.

[Example 2] FIG. 2 is a circuit diagram of a second embodiment of the present invention.

In this embodiment, a bistable relay (so-called latching relay) is used as the switching relay. S,
, S are contacts of a switching relay, which includes a common terminal and first and second switching terminals.

The common terminal is connected to the entrance unit G, the first switching terminal is connected to the i-th dwelling unit J1, and the second switching terminal is connected to the second dwelling unit J2.

First, when the second dwelling unit J2 is not operating, the DC voltage of the transmission line connected to the second dwelling unit J2 is low, so no current flows through the set coil SC of the bistable relay. the common terminal is connected to the first switching terminal;
The entrance device G is connected to the first dwelling device J1. In this state, the operation is similar to that of the conventional example shown in FIG.

Next, when the monitor switch 4 is operated or the handset 2 is raised on the second dwelling unit J2, the second dwelling unit J2
Supply of DC current starts from.

A full wave rectifier DB is installed on the transmission line connected to the second housing unit J2.
is connected, and its rectified output causes current to flow through the set coil SC of the bistable relay via the Zener diode ZD, and its common terminal is connected to the second switching terminal. As a result, the entrance unit G is connected to the transmission line connected to the second dwelling unit J2, and the line voltage decreases.
The Zener diode ZD enters the cutoff state, and the current flowing through the set coil SC stops. Further, the capacitor C is charged by the rectified output of the full-wave rectifier DB via the resistor R1 and the diode D2. At this time, transistor Q2
Since the base potential of is the potential at the connection point between the diode D and the resistor Rs, it does not become lower than the emitter potential, and no base current flows, so it is kept in the off state.

Next, when the second dwelling unit J2 finishes the call operation, the second
Since the DC voltage of the transmission line connected to the housing unit J2 becomes low, a base current flows through the transistor Q2 due to the accumulated charge in the capacitor C3, and the transistor Q2 is turned on. As a result, the accumulated charge in the capacitor CI flows to the reset coil RC, and the common terminal of the bistable relay is switched and connected to the first switching terminal. For this reason, the entrance device G
is again connected to the first dwelling unit Jl.

In this embodiment, a bistable relay is used as the switching relay, so it is only necessary to apply the drive current when setting, and there is no margin in the DC current supplied from the second dwelling unit J2 to the entrance unit G. suitable for In addition, since the drive current at the time of reset is secured by the accumulated charge of the capacitor C1, when the second dwelling unit J2 finishes the call operation,
It becomes possible to switch and connect the entrance device G to the first dwelling unit J1, and it is possible to realize an operation in which the first dwelling unit J is used preferentially over the second dwelling unit J2.

Although not particularly shown, if a full-wave rectifier is also connected to the transmission line connected to the first residential unit J, and a reset coil RC is connected to the rectified output via a Zener diode, a capacitor for driving the reset coil can be connected. C1, transistor Q2, diodes D, D, resistors R4, Rs
etc. can be omitted.

In this case, the timing at which the common terminal is switched and connected to the first switching terminal is not when the second dwelling unit J2 finishes the call operation, but when the monitor switch 4 is operated on the side of the first dwelling unit J. or when the handset 2 is lifted. In other words, in this case, two housing units J , , J
2, the one used last will be connected to the entrance device G preferentially.

Although the above embodiment has been described on the assumption that an electromagnetically driven relay is used as the switching relay, it goes without saying that a semiconductor relay may also be used.

[Effects of the Invention] The switching type intercom according to the present invention is provided with a switching relay that uses part of the DC current supplied from the dwelling device to the entrance device as an operating power supply, so that the operating dwelling device can Since it is automatically connected to the entrance device and has a simple configuration, it has the effect of realizing reliable switching operation.

In addition, in the invention recited in claim 2, since a monostable relay is used as the switching relay, there is an effect that the switching device can be realized with a very simple configuration.

In addition, in the invention described in claim 3 or 4, since a bistable relay is used as the switching relay, it is only necessary to flow the drive current during the switching operation, and the direct current is supplied from the dwelling unit to the entrance unit. It has the advantage that it can be used even when there is not enough current.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a first embodiment of the present invention, FIG. 2 is a circuit diagram of a second embodiment of the present invention, and FIG. 3 is a schematic configuration diagram of a conventional example.
Figure 4 is an explanatory diagram of the same operation as above, Figure 5 (a), (b)
FIG. 2 is a block diagram showing a more detailed configuration of a conventional example. G is the entrance device, J, , , J is the housing unit, K is the switching device, l is the transmission line, and R is the switching relay.

Claims (4)

[Claims] (1) Connect the entrance unit and the housing unit via a pair of transmission lines,
In an intercom that supplies direct current, which serves as an operating power source for the entrance device, from the dwelling device to the transmission line, and multiplex transmits at least an audio signal via the transmission line, one entrance device and one of the plurality of dwelling devices are connected. A switching intercom characterized in that the switching device is equipped with a switching relay that uses a part of the direct current supplied from the dwelling device to the entrance device as an operating power source. (2) In the switching relay, the common terminal is connected to the entrance unit, the normally closed terminal is connected to the first unit, the normally open terminal is connected to the second unit, and the transmission is connected to the second unit. 2. The switchable intercom according to claim 1, wherein the switchable intercom is a monostable relay driven by direct current supplied from the line so that the common terminal is switched to the normally open terminal. (3) The switching relay is a bistable relay whose common terminal is connected to the entrance unit, the first switching terminal is connected to the first dwelling unit, and the second switching terminal is connected to the second dwelling unit. and
The switching device includes a switching control means for driving a bistable relay so as to switch and connect the common terminal to the second switching terminal using a direct current supplied from a transmission line connected to the second dwelling unit; A charge accumulating means is charged by a direct current supplied from a transmission line connected to a second dwelling unit, and a common terminal is charged by the accumulated charge of the charge accumulating means when the direct current supplied from a transmission line connected to a second dwelling unit is interrupted. 2. The switching intercom according to claim 1, further comprising switching release control means for driving the bistable relay so as to switch the bistable relay to the one switching terminal. (4) The switching relay has a common terminal connected to the entrance unit, a first switching terminal connected to the first dwelling unit, a second switching terminal connected to the second dwelling unit, and a first switching terminal connected to the first dwelling unit. The common terminal is switched to the first switching terminal by the DC current supplied from the transmission line connected to the unit, and the common terminal is switched to the second switching terminal by the DC current supplied from the transmission line connected to the second unit. 2. The switchable intercom according to claim 1, wherein the switchable intercom is a bistable relay that is driven to be switched and connected.