JP2781061B2 - Two-wire TV intercom system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a multi-wire, two-wire TV intercom system.

[Prior Art] FIG. 7 is a block diagram showing a schematic configuration of a conventional example, in which a plurality of slave units 1 provided with a television camera 5 with respect to a plurality of master units 4. The transmission lines 3 are connected to form a system.

FIG. 8 is a block diagram showing the repeater 6 more specifically. The transmission lines 3 connected to the slaves 1 are connected to the slave selector 9 in the repeater 6 via the slave connection lines 14. The slave unit connection lines 14 are connected to the slave unit operation detecting units 10.

On the other hand, the transmission lines 3 connected to the base units 4 are connected to the base unit selection unit 11 via the base unit connection lines 15 in the repeater 6, and the base unit connection lines 15 are connected to the base unit. The motion detection units 12 are connected. The slave unit selection unit 9 and the master unit selection unit 11 are connected by two connection lines 13, and the connection line 13 includes a one-way buffer amplifier unit 16 having the slave unit selection unit 9 as an input, and a buffer amplifier Dummy load section 18 connected in parallel to the output end of section 16
, And the base unit connection line 15 via the circuit of the switching unit 17 ...
Connected to

The operation of the circuit shown in FIG. 8 will be described with reference to the drawing. In the standby mode, among the master units 4, the switching units 17 controlled by the control signal S of the master unit selection unit 11 are separated from the dummy load unit 18. Through the transmission line 3, the base unit connection line 15, the base unit selection unit 11, the connection line 13, the handset selection unit 9, the handset connection line 14,. The standby voltage is applied to each of the slaves 1... From the initially set master 4.

When the call button 2 of the present slave 1 is operated, the standby voltage is forcibly and instantaneously dropped by the slave 1, and this voltage drop is caused by the slave operation of the repeater 6 corresponding to the slave 1. Detected by the detection unit 10.

The change in the standby voltage is performed through the transmission line 3, the slave unit connection line 14, and the slave unit selection unit 9, and then to the connection line 13, the master unit selection unit 11, the master unit connection line 15, the route of the transmission line 3, and Line 13, buffer amplifiers 16 for modulated waves of video signals and call audio signals, dummy load units 18, switching units 17, master unit connection lines 15, transmission lines 3.
Are transmitted to the parent devices 4.

Here, when the slave unit operation detection unit 10 detects a drop in the standby voltage, the detection output is transmitted to the slave unit selection unit 9 and the transmission line 3 and the slave unit connection of the slave unit 1 whose call button 2 is operated. Line 14
The connection line 13 in the repeater 6 is connected to the slave unit selecting unit 9 with low loss.

.., Which have been activated upon detecting the change in the standby voltage, are separated from the dummy load unit 18 by the switching unit 17 controlled by the control signal S of the master unit selection unit 11 and are connected to the connection line 13. The operating voltage from the above-mentioned master unit 4 which is initially set to be connected to the transmission line 3, the master unit connection line 15, the master unit selection unit 11, the connection line 13, the slave unit selection unit 9, and the slave unit connection The signal is transmitted to the handset 1 on which the call button 2 is operated via the line 14 and the transmission line 3 so that the video signal and the voice signal of the handset 1 can be transmitted.

Since the dummy load units 18 are connected to the transmission lines 3 of the activated base units 4 through the switching unit 17 controlled by the base unit selection unit 11 through the base unit connection lines 15, the connection lines
13 are separated from each other, and these master units 4... Continue to supply operating voltages with the addition of dummy load units 18.

As described above, the two-wire TV intercom system completes the start-up operation and shifts to the call operation. By the way, the base unit 4 which has shifted to the call operation performs a timer operation, and the handset 8 of the base unit 4
Seconds and off-hook (during a call), the call operation is forcibly terminated in about 3 minutes.

Here, as shown in FIG. 9 (a), when the handset 8 is off-hook, the tone signal generating circuit 28 for generating a tone signal of, for example, about 20 KHz out of the band of the call voice signal is provided on the base unit 4 side. the off-hook signal oF of "H" is input to the base of the transistor Q ₃ to turn on the transistor Q _3, a switch circuit 29 for passing the tone signal, from the tone signal and the handset 8 side that has passed through the switch circuit 29 Mixing circuit 30 that mixes with voice signal TS
And a carrier wave (for example, 6.5 MHz) by this mixed signal
And an FM modulation circuit 31 for FM-modulating the signal. On the other hand, the master unit operation detecting unit 12 converts the FM modulated wave carried as shown in FIG. 9 (b) into a general-purpose FM reception demodulation IC [for example, ANA763 ( Model name)]
32, an FM demodulation circuit 33, a high-pass filter 34 that passes only the tone signal from the signal demodulated by the FM demodulation circuit 33, and a general-purpose tone decoder IC that decodes the tone signal that has passed through the high-pass filter 34 [ NJM567
(Model name)] By providing a tone decoder circuit 36 using a 35 and a comparison circuit 37 for turning on the decoder output and outputting a detection signal of an off-hook signal, in this conventional example, the handset 8 of the base unit 4 is provided. Off-hook is detected by the base unit motion detection unit 12.

As shown in FIG. 10 (a), a handset 8 is provided by using an off-hook signal generation circuit 38 comprising a Colpitts oscillation circuit which operates when the off-hook signal OF is input to the base unit 4.
At the time of off-hook, for example, a signal of another carrier frequency, for example, 10.7 MHz, other than the carrier signal of the video signal and the voice signal is generated and transmitted, and as shown in FIG. 10 (b), A reception amplifier circuit 39 for receiving and amplifying a signal of 10.7 MHz, and a comparison circuit 40 for generating a detection signal when a received signal is continuously received for a certain period of time and an integrated value thereof is equal to or higher than a certain level are provided. There is also a circuit example for detecting off-hook of the handset 8.

8 correspond to the inputs A to C and X of the base unit selection unit 11.

Figure 11 is slave unit 1 ₁ of the two, 1 ₂ and base unit 4 ₁ of two, 4 ₂ shows a circuit of a conventional example of a combination of a master unit in this circuit
4 ₁ through the transmission line 3 ₁ , the base unit connection line 15 ₁ , the normally closed NC of the relay contacts ra ₁ and rb ₁ of the latching relay of the base unit selection unit 11, the connection line 13, and the slave unit selection unit 9. slave unit 1 ₁ each, in 1 ₂ is adapted to apply supply standby voltage.

Child selecting unit 9 applies a standby voltage to the slave unit 1 ₁ relay contacts rc, through a normally closed side NC of rd, for the Matako unit 1 ₂ is connected to the NO side of the relay contact rc resistance And the standby voltage is applied through the terminals. The slave unit 1 _1, 1 ₂ in the standby state in the high impedance, the voltage between the transmission lines 3 _1, 3 ₂ Since the current is very small flows is set to standby voltage not affected by the resistance.

Connection line connected between relay contacts ra ₁ , rb ₁ and rc, rd
An input terminal of the buffer amplifier unit 16 is connected to 13 via a DC cut circuit 21 and a removal filter 22, and a dummy load unit 18 is connected to an output terminal of the buffer amplifier unit 16.

Master station 4 ₁ and the transmission line 3 _1, via the base unit connection line 15 ₁ is connected between the NC side and NC side of the relay contact rb ₁ of the relay contact ra _1, also the relay contacts ra ₂ NO connected between the NO side of the side and relay contacts rb _2, base unit 4 ₂ and the transmission line 3 _2, the relay contact ra ₁ via the base unit connection line 15 ₂ NO side and relay contacts ra ₂ It is connected between the NO side and N-side of the relay contacts rb _2. Both ends of the dummy load section 18 are connected between the common terminals of the relay contacts ra ₂ and rb ₂ .

Also in each base unit connection lines 15 _1, 15 ₂ X, X, Y, connects the base unit connection detection unit 12 _1, 12 ₂ as indicated by an arrow Y, the base unit connection detection unit 12 ₁ , detection output 12 ₂ is inputted to the logic circuit of the base unit selection unit 11. The logic circuit of the exciting coil RYa excitation driven by turning on the transistor Q ₁ through the OR gate 23 if, for example, the detection output of the base unit connection detection unit 12 ₁ is "H", the relay contact ra _1, rb _1, Switch ra ₂ and rb ₂ from NO side to NC side. The turns on the transistor Q ₂ and excitation drive the excitation coil RYb through AND gate 24 if the detection output of the base unit connection detection unit 12 ₁ is "H", the relay contact r
Switch a ₁ , rb ₁ , ra ₂ , rb ₂ from the NC side to the NO side. Both detectors
If the detection outputs of 12 ₁ and 12 ₂ are both “L”, INV gates 25 and 26
Transistor through the AND gate 27 and OR gate 23
The Q ₁ turns on to drive the relay RYA, the relay contact r
Switch from the NO side of a ₁ , rb ₁ , r ₂ , rb ₂ to the NC side. Both detectors
If the detection outputs of 12 ₁ and 12 ₂ are both “H”, the transistor Q ₁ is turned on through the OR gate 23 to drive the relay RYa,
The relay contacts ra ₁ , rb ₁ , ra ₂ , rb ₂ are switched from the NO side to the NC side.

On the other hand, slave unit connection detecting sections 10 ₁ and 1 are connected to slave unit connection lines 14 ₁ and 14 ₂ , respectively.
0 ₂ is connected, slave unit 1 ₁ or 1 _2, if lowering of the standby voltage by the call operation is performed, which slave unit connection detection unit 10 ₁ or 1
0 ₂ detects this and drives the relay RYc or RYd to change the relay contact rc or rd from the NO side to the NC side and vice versa.
It is designed to switch to the side.

If this way in Fig. 11 circuit is one of the base unit 4 ₁ and 4 ₂ are connected to the connection line 13 through a relay contact ra _1, rb ₁ of the master unit selecting unit 11, the other master station 4 ₂ or 4 ₁ is a dummy load section 18 through relay contacts ra ₂ and rb ₂ which constitute a switching section 17.
It becomes connected state, the buffer amplifier section 16 in the parents unit 4 _1, 4 _2, the dummy load unit 18, so as to share the switching unit 17.

In each of the above-mentioned conventional examples, the dummy load unit 18 is configured by a circuit having a resistance value corresponding to the power consumption capacity of the slave unit. However, it is necessary that the resistance value be infinite, that is, released. Switching between the resistance value and infinity is appropriately performed. It is also conceivable that the standby voltage and the operating voltage are set to the same voltage, and the current value or the current flowing time to the slave 1 is made different between the standby time and the operating time. It is also conceivable that the repeater 6 is incorporated in the slave 1 or the master 2.

[Problems to be Solved by the Invention] However, in the above-described conventional example in which multiple stations are provided, only one repeater can be interposed between a plurality of master units and a plurality of slave units in practice. There is a problem that even if an attempt is made to add a parent device by connecting the base units, it cannot function as a two-wire TV intercom system.

The present invention has been made in view of the above-described problems, and provides a two-wire TV intercom system in which a base unit can be added by connecting a plurality of repeaters using a simple configuration. Aim.

Means for Solving the Problems In order to achieve the above-mentioned object, the invention according to claim 1 provides a child device provided with a monitor television camera, a parent device provided with a monitor television, a parent device and a child device. And a two-line transmission line for transmitting a video signal from the slave unit and a speech voice signal between the master unit and the slave unit. A standby voltage of a constant voltage during standby is set via the transmission line. To the base unit by operating the calling unit of the slave unit, the standby voltage value is instantaneously changed in conjunction with the operation of the calling unit of the slave unit, and the call to the master unit is notified by this change. A two-wire television intercom system for supplying operating voltage to a slave unit for a fixed time from a master unit activated in response to a call from the slave unit via a transmission line, wherein one of the master unit and the slave unit is used. With each so that at least a plurality of A repeater is interposed between the master unit and the slave unit. The repeater unit is provided for each slave unit to be connected, and detects a change in the standby voltage to the corresponding slave unit and generates a control output. A slave unit having a slave unit operation detection unit, a connection end for connecting a plurality of slave units, and a connection end for connecting a connection line to the master unit, and a calling operation performed by an output of the slave unit operation detection unit; A slave selection unit for selectively connecting to a connection line; and a master unit provided for each master unit connected via a separate transmission line and detecting off-hook information of a handset of the master unit transmitted through the transmission line. An operation detection unit, a connection end for connecting the transmission line from each master unit to the transmission line, and a connection end for connecting to the connection line. A base unit selection unit for selectively connecting between the connection lines, a transmission line connecting each base unit, and the connection line A buffer amplifier that transmits a signal in one direction from the connection line side to the transmission line side, and an operating voltage that is connected in parallel to the output side of the buffer amplifier unit and is supplied from the master unit connected to the transmission line. A dummy load unit to be absorbed, and a switching unit inserted between the dummy load unit and the transmission line from the master unit to receive a control signal from the master unit selection unit and control the connection between the dummy load unit and the transmission line. In the two-wire TV intercom system, the main unit is connected to a main unit operation detecting unit that detects off-hook information transmitted from the main unit and reaching the repeater, and receives an output from the main unit operation detecting unit to perform a transmitting operation. A signal generator that generates the same signal as the off-hook information of the master unit, and transmits the output of the signal generator to another repeater.

According to a second aspect of the present invention, in the two-wire TV intercom system, the base unit operation detecting unit detects off-hook information transmitted from the base unit and reaching the relay unit, and outputs the output of the base unit operation detecting unit. A signal generator for receiving and transmitting a signal is provided, the output signal of the signal generator is made the same as the off-hook information of the master unit, and the output of the signal generator is transmitted to another repeater.

According to a third aspect of the present invention, the value of the standby voltage and the value of the operating voltage are made equal, and the current value in the standby state and the current value during the operation or the time during which the current continuously flows are different.

The invention according to claim 4 separates the repeater and the base unit during standby, transmits a standby voltage to the slave unit from the repeater, and connects the repeater and the base unit when there is a call operation in the slave unit. Is what you do.

In the invention according to claim 5, the slave unit and the repeater are connected at the time of initial setting and the relay and the master are disconnected from each other, and the standby voltage to the slave during standby is transmitted from the repeater, The relay unit and the master unit are connected when the calling operation of the slave unit is detected by the slave unit operation detection unit.

[Operation] According to the first aspect of the present invention, the master unit operation detecting unit detects off-hook information from the master unit and transmits the off-hook information to another repeater even after the repeater is switched. Therefore, the detection of off-hook information can be ensured in other repeaters, so that the repeater can be connected in a subordinate manner, and the base unit can be easily added.

According to the second aspect of the present invention, after the operation of the master unit operation detector, the signal generator is operated to transmit the same signal to other repeaters as the off-hook information of the master unit. Can be detected and transmitted between the repeaters, so that the subordinate connections of the repeaters can be made, and the base unit can be easily added,
In particular, the time limit of relay transmission of off-hook information is not limited, and the number of subordinate connections of the relay device can be increased.

EXAMPLES The present invention will be described below with reference to examples.

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of the invention according to claim 1, wherein a plurality of slaves 1 are transmitted to a plurality of masters 4 via a plurality of repeaters 6. The system is constructed by connecting with the line 3.

FIG. 2 shows a specific configuration of the repeater 6 used in the embodiment. The basic configuration of the repeater 6 is the same as the conventional example shown in FIG. Base unit motion detection unit
12 uses a master unit operation detecting unit 19 having a unique configuration different from that of the slave unit 12. The slave unit operation detecting unit 10 is connected to the slave unit via the slave unit connection line 14 and the transmission line 3 as in the related art. 1 and the base unit 4 can be connected to the base unit operation detection unit 19 via the base unit connection line 15 and the transmission line 3, as shown in FIG. When the slaves 6 are cascaded, another repeater 6 can be connected via the transmission line 3 in the same manner as the slave 1, and another repeater 6 can be connected via the transmission line 3 in the same manner as the master 4. You can do it.

Circuit elements having the same operation and configuration as those of the conventional example shown in FIG. 8 are denoted by the same reference numerals as those of the conventional example shown in FIG. 8, and description thereof is omitted.

Parent device operation detecting portion 19 is configured from a comparator unit and the detection unit 19b and the amplifier 19a as shown in FIG. 3 (not shown), the detection time t ₁ for off-hook information from the calling duration T ₀ of the off-hook information It is set very short.

Next, the operation of the parent machine operation detecting section 19 will be described with reference to the timing chart shown in FIG.

Now, when a call is started from an arbitrary slave unit 1 in FIG. 1, the relay unit of FIG. 1, for example, the most child among a plurality of repeaters 6 ₃ interposed between the master unit 4 and the slave unit 1. vessel 1 from remote relays 6 ₃ for any connected master unit (parent machine startup,
In the case where the dummy load unit 18 connected to Assumes) taking 4 of the handset 8 attempts to start a call, the base-operation detecting portion 19 of the relays 6 ₃ connected to the parent machine 4
Receives the off-hook information (transmission duration time T ₀ ) shown in FIG. 4 (a).

This off-hook information is stored in the detection unit 19 in the base unit operation detection unit 19.
4 (b), and the output waveform is compared with a threshold voltage by a comparator, and an extremely short response time t ₁ (approximately 1 / at most of the transmission duration time).
2 or less) and transmits it to the parent device selection unit 11 (FIG. 4 (c)). In response to the detection signal, the base unit selecting unit 11 disconnects the dummy load unit 18 from the base unit 4 that picks up the handset 7, and the base unit 4 is directly connected to the base unit 4 via the base unit selecting unit 11, the child unit selecting unit 9, and the like. it means that the connected other directly relays 6 _2, off-hook information having the outgoing duration of taking the repeater 6 ₂ (T ₀ -t ₁₎ is the parent machine operation detecting portion 19 of the relays 6 ₂ received, it is detected by an extremely short response time t ₀ with producing an output waveform of FIG. 4 is detected by the detection unit in the base unit operation detecting section 19 (d), relays 6 ₂ of the master unit selecting unit 11 4th
It is transmitted as shown in FIG.

As a result, base unit selection unit 11 of the relays 6 ₂ directly and child-side terminals a calling signal is detected from the base-side terminal and the slave unit 1 has been detected off-hook information over the base unit selection unit 11 while connected, it relays 6 ₂ sequentially connected relays 6 ₁
Off-hook information (the transmission duration of T ₀ −2t ₁ ).

And as thus, it relays 6 ₁ also receives the off-hook information from the relays 6 ₂ performs the same operation as relays 6 ₂ and relays 6 _3.

As a result, a repeater intervening on the way from the handset 1 in which the call is activated to the master unit 4 in which the off-hook information is generated.
, Including 6 ₁ ..., are directly connected with low loss, so that video signals and speech voice signals can be transmitted between the two.

FIG. 5 shows an embodiment of the second aspect of the present invention. In this embodiment, each repeater 6 generates the same signal as the off-hook information generating means (not shown) provided in the base unit 4. It differs from the circuit of FIG. 8 in that a signal generator 20 is provided.

The operation of the circuit of this embodiment will be described with reference to the timing chart of FIG.

Now, if the system is calling started from any slave unit 1, any base unit which is connected to the relays 6 ₃ shown in Fig. 1 4 (parent machine 4 startup, and is connected to the Damirodo portion in case of attempting to initiate a call by taking the handset 8 of the assumed) and are, relays 6 ₃ connected the parent machine 4
The parent machine operation detecting section 12 receives the off-hook information (transmission duration time T ₀ ) shown in FIG. 6 (a).

This off-hook information is detected by a detection unit (not shown) of the base unit operation detection unit 12 to generate an output waveform shown in FIG. 6B, and this waveform is compared with a threshold voltage by a comparison unit. was detected by the response time t _2, it is transmitted to the base unit selection unit 11 as shown in FIG. 6 (c).

In response to the detection signal, the master unit selecting unit 11 disconnects the dummy load unit 18 from the master unit 4 that has picked up the handset 8, and the master unit selecting unit 11
11 directly another relay machine, that is, call start resulting in handset 1 of another that is directly connected relays 6 ₁ or intervention of the repeater is high, toward the base unit 4 side from the relay device To another connected repeater.

At this time, operating the signal generator 20 in the relays 6 ₃ simultaneously created to indicate the same signal off-hook information from the base unit 4 to FIG. 6 (d), relays the signal as a off-hook information It will be submitting towards the machine 6 ₂ or relays 6 _1.

And as thus, it relays 6 ₂ also receives the off-hook information reproduced by the relays 6 _3, the relays 6 ₂ above the parent device operation detecting portion 12 as shown in Figure No. 6 (e) and performs detection in the same manner, also detected waveform and thread hold voltage above relays 6 an operation for transmitting to the main unit selecting unit 1 as shown and the resulting detection output in FIG. 6 (f) by comparing the ₃ Perform in the same manner as described above.

The above operations are sequentially performed by the related repeaters 6 _1, ..., So that the repeaters 6 _3, .. It will be connected with the bottom loss.

Incidentally may be different standby voltage during standby to equal the value of the operating time of voltage and operating time of time flowing current value or the current is continued, and in the standby state relays 6 ₃ and base unit 4 Separate the bets, relays 6 ₁ child device 1 a standby voltage transfer to, and relays 6 ₃ there is a call operation in slave unit 1
And base unit 4 may be connected. Further and relays 6 ₃ as the connection state slave unit 1 and the relay unit 6 ₁ during initialization
When the a state disconnected from the base unit 4, the standby voltage to the slave unit 1 in a standby state transmitted from the relay apparatus _61, detects the call operation of the slave unit 1 at slave unit operation detecting portion 10 it may be connected to the relays 6 ₃ and base unit 4.

[Effects of the Invention] In the present invention, in the two-wire TV intercom system, the detection time for the off-hook information of the base unit operation detection unit for detecting the off-hook information reaching the repeater is set to be shorter than the transmission duration of the off-hook information. Therefore, after the off-hook information from the master unit is detected by the master unit operation detection unit and the relay unit is switched, the off-hook information can be transmitted to another repeater unit. However, there is an effect that the detection of off-hook information is ensured, the subordinate connection of the repeater can be performed, and the expansion of the master can be easily performed.

According to a second aspect of the present invention, in the two-wire TV intercom system, the base unit operation detecting unit detects off-hook information transmitted from the base unit and reaching the relay unit, and outputs the output of the base unit operation detecting unit. A signal generator for receiving and transmitting a signal, and making the output signal of the signal generator the same as the off-hook information of the master unit and transmitting the output of the signal generator to another repeater unit. After the operation of the operation detection unit, the signal generator is operated to transmit, and the same signal as the off-hook information of the master unit can be transmitted to another repeater, and the off-hook information can be detected and transmitted between the repeaters, Therefore, the slave unit can be connected in a subordinate manner, and the base unit can be easily added. In particular, the invention of claim 1 has a time limit for relay transmission of off-hook information. Not depend on the relay device There is an effect that it is possible to increase the number.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a two-wire TV intercom system of the present invention, FIG. 2 is a circuit configuration diagram showing a specific configuration of a repeater according to an embodiment of the present invention described in claim 1, and FIG. FIG. 4 is a circuit diagram of a parent machine operation detecting unit used in the machine, FIG. 4 is a timing chart for explaining the operation of the same, and FIG.
FIG. 6 is a circuit configuration diagram showing a specific configuration of the repeater according to the embodiment of the invention described, FIG.
FIG. 7 is an overall configuration diagram of a conventional two-wire TV intercom system, FIG. 8 is a configuration diagram showing a specific configuration of the repeater, and FIG. 9 (a) is a handset of a base unit used in the same. FIG. 9 (b) is a circuit diagram of a base unit operation detecting unit used in the above embodiment, and FIG. 10 (a) is a circuit diagram of the off-hook information transmitting unit of the handset of the base unit used in the embodiment. FIG. 10 (b) is a circuit diagram of another example of the master unit operation detecting unit used in the embodiment, and FIG. 11 is a configuration diagram showing a specific configuration of another conventional repeater unit. 1 is a slave unit, 2 is a push button, 3 is a transmission line, 4 is a master unit, 5 is a monitor television camera, 6 ₁ is a repeater, 7 is a monitor television,
8 is a handset, 9 is a handset selection unit, 11 is a base unit selection unit,
Reference numeral 18 denotes a dummy load unit, 12 and 19 denote parent device operation detection units, 19a denotes an amplification unit, 19b denotes a detection unit, and 20 denotes a signal generator.

Continuation of the front page (72) Inventor Masahiko Amano 1048 Odomo Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works, Ltd. (58) Field surveyed (Int.Cl. ⁶ , DB name) H04Q 3/58 H04M 11/00 H04M 9/00

Claims (5)

(57) [Claims] 1. A child device provided with a monitor television camera,
It consists of a master unit equipped with a monitor television, and two transmission lines for connecting the master unit and the slave unit and transmitting a video signal from the slave unit and a voice signal between the master unit and the slave unit. A constant standby voltage is supplied to the slave unit via the transmission line, and when calling the base unit by operating the calling unit of the slave unit, the standby voltage value is instantaneously linked with the operation of the calling unit of the slave unit. The basic system consists of notifying the call to the master unit by this change and supplying the operating voltage to the slave unit for a certain period of time via the transmission line from the master unit that started operation in response to the call from the slave unit. A master unit and a slave unit are provided so that at least one of them is at least a plurality, and a repeater is interposed between the master unit and the slave unit. , Which detects and controls changes in standby voltage to the corresponding slave unit. A child unit having a slave unit operation detecting unit for generating a force, a connection end for connecting a plurality of slave units, and a connection end for connecting a connection line to the master unit, and a calling operation performed by an output of the slave unit operation detection unit; Handset selection unit for selectively connecting a handset to the connection line, and off-hook information of the handset of the base unit, which is provided for each base unit connected via a separate transmission line and transmitted through the transmission line, is detected. A base unit operation detecting unit, a connection end for connecting the transmission line from each base unit respectively, and a connection end for connecting to the connection line, and transmission of the base unit during a call based on a detection output of the base unit operation detection unit. Master unit selecting unit for selectively connecting between a line and the connection line, and a buffer for transmitting a signal in one direction from the connection line side to the transmission line side between the transmission line connecting each master unit and the connection line The amplifier and the output side of the buffer amplifier are connected in parallel and connected to the transmission line. A dummy load section that absorbs the operating voltage supplied from the machine side, and is inserted between the dummy load section and a transmission line from the master machine side to receive a control signal from the master machine selection section and transmit to the dummy load section. And a switching unit for controlling connection to a line, in a two-wire TV intercom system, the off-hook information transmitted from the base unit through the transmission line is continuously transmitted from the base unit for a certain period of time when there is an off-hook, and the relay unit Has a relay terminal connected to the connection end of another repeater that connects the transmission line from the master, and a time from when the off-hook information of the master operation detection unit is received to when it is determined to be off-hook. Is set to be shorter than the predetermined time, and a function of relaying off-hook information from the master unit to another repeater terminal through the relay terminal when it is determined to be off-hook is provided. Two-wire TV intercom system to butterflies. 2. A child device provided with a monitor television camera,
It consists of a master unit equipped with a monitor television, and two transmission lines for connecting the master unit and the slave unit and transmitting a video signal from the slave unit and a voice signal between the master unit and the slave unit. A constant standby voltage is supplied to the slave unit via the transmission line, and when calling the base unit by operating the calling unit of the slave unit, the standby voltage value is instantaneously linked with the operation of the calling unit of the slave unit. The basic system consists of notifying the call to the master unit by this change and supplying the operating voltage to the slave unit for a certain period of time via the transmission line from the master unit that started operation in response to the call from the slave unit. A master unit and a slave unit are provided so that at least one of them is at least a plurality, and a repeater is interposed between the master unit and the slave unit. , Which detects and controls changes in standby voltage to the corresponding slave unit. A child unit having a slave unit operation detecting unit for generating a force, a connection end for connecting a plurality of slave units, and a connection end for connecting a connection line to the master unit, and a calling operation performed by an output of the slave unit operation detection unit; Handset selection unit for selectively connecting a handset to the connection line, and off-hook information of the handset of the base unit, which is provided for each base unit connected via a separate transmission line and transmitted through the transmission line, is detected. A base unit operation detecting unit, a connection end for connecting the transmission line from each base unit respectively, and a connection end for connecting to the connection line, and transmission of the base unit during a call based on a detection output of the base unit operation detection unit. Master unit selecting unit for selectively connecting between a line and the connection line, and a buffer for transmitting a signal in one direction from the connection line side to the transmission line side between the transmission line connecting each master unit and the connection line The amplifier and the output side of the buffer amplifier are connected in parallel and connected to the transmission line. A dummy load section that absorbs the operating voltage supplied from the machine side, and is inserted between the dummy load section and a transmission line from the master machine side to receive a control signal from the master machine selection section and transmit to the dummy load section. A two-wire TV intercom system, comprising: a switching unit that controls connection to a line; and a base unit operation detection unit that detects off-hook information that is transmitted from the base unit and reaches the relay unit. A signal generator for generating a transmitting operation in response to the output of the detection unit, wherein the output signal of the signal generator is made the same as the off-hook information of the master unit, and the output of the signal generator is transmitted to another repeater. Characteristic two-wire TV intercom system. 3. The system according to claim 1, wherein the standby voltage and the operating voltage are made equal and the current value during the standby operation and the current value during the continuous operation are different.
The described two-wire TV intercom system. 4. In a stand-by mode, the repeater and the base unit are separated from each other, and a standby voltage for the slave unit is transmitted from the repeater unit. When a call operation is performed on the slave unit, the repeater unit and the base unit are connected. The two-wire TV intercom system according to claim 1 or 2, wherein: 5. The slave unit and the repeater are connected at the time of initial setting and the relay unit and the master unit are disconnected from each other, and a standby voltage to the slave unit during standby is transmitted from the repeater. The two-wire TV intercom system according to claim 1 or 2, wherein the relay device and the master device are connected at the time when the call operation of the slave device is detected by the slave device operation detection unit.