JPH0235888A - Television interphone system - Google Patents

Abstract

PURPOSE:To obtain a guide when a signal line is provided by operating a test switch provided inside a master machine when an interphone system is provided, and issueing an alarm when a current value supplied from the master device to a slave device is <= the prescribed value. CONSTITUTION:When the signal line of the interphone system is provided, the constant current at a high level is sent through a balun 15 and a terminal T1 to a transmission line l by the operation of a test switch SW. The returned current from the slave device 2 side is grounded through a terminal T2, the balun 15 and a resistance RT. That is, the current returned from the master device 1 and the slave device 2 is converted to a voltage at both ends of the resistance RT, and the voltage is compared with a reference voltage VREF by a comparator CMP of a monitor circuit 12. When the voltage at both ends of the resistance RT is lower than the reference voltage VREF, a transistor Q4 of an alarm circuit 13 is driven, conducted through a resistance R5 to a light emitting diode L, and displayed by lighting up a lamp.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a television interbon system, and more particularly to an abnormal state notification circuit when transmission loss in a signal line exceeds a specified value.

[Conventional technology] In order to be able to see visitors indoors, a television camera is installed on the side of the intercom unit installed at the entrance.
A TV intercom system, in which a monitor TV is installed on the side of the intercom base unit installed indoors so that a video can be displayed simultaneously with a call, has been developed and used.

As shown in FIG.
When the user operates the call button 200a of 00, a call signal is transmitted to the intercom host @100 provided in the room through the signal line l, and a ring tone is output from the speaker 100c.

Then, when the resident picks up the Hunt Sera) 100a and responds, power is supplied to the TV camera 200b of the slave device 200, and a video signal is sent to the i-device 100 through the wiring 1, and is displayed as an image on the TV monitor 100b. At the same time, a telephone conversation is made.

FIG. 5 shows a block diagram of the configuration of this television intercom system.

This system is composed of an intercom base unit 100 installed indoors with a monitor TV TV, and an intercom slave unit 200 installed at the entrance with a monitor camera TVC. It is connected through a dedicated signal line β such as a coaxial cable, power is supplied to the slave unit 200 from the base unit 100, and video, audio, and control signals are multiplexed and necessary information communication is performed. .

To explain the more specific configuration, intercom parent fil
00 is a variable constant current power supply circuit 101.00 for supplying power to the child device 200 side. A modulating section 103. that modulates a high frequency signal using the audio signal from the tone signal generation circuit 102 when the alarm switch AL is operated in an emergency. A demodulator 104 demodulates the modulated signal sent from the slave device 200 side and extracts a tone signal and a voice signal to be transmitted as a calling signal.
゜Balanced input/output circuit 105 that inputs the modulation signal output from the modulation section 103 and outputs the modulation signal sent from the slave device 200 side via the signal line l to the demodulation section 104.
．． The power supply current of the variable constant current power supply circuit 101 is superimposed on the modulated output of the balanced input/output circuit 105, and the slave unit 20 is connected to the signal line l.
The modulation section 103 mixes the voice signal from the handset H and the tone signal from the tone signal generation circuit 102 in the voice/tone mixing circuit 103a. After that, these signals are input to the modulation circuit 103b, and the high-side S signal fl, which becomes the first carrier, is modulated, and the bandpass filter 10
The demodulator 104 includes a bandpass filter 104a that selects the frequency band of the modulated signal from the balanced input/output circuit 105, and a bandpass filter 104a that selects the frequency band of the modulated signal from the balanced input/output circuit 105. A demodulation circuit 104b for demodulating, a voice/tone separation circuit 104c for separating the demodulated signal into a tone signal corresponding to the ejection signal sent from the child device 200 side and a voice signal, and a voice signal amplification circuit 104c. It has a circuit 104d and a tone signal amplification circuit +04e, and the output of the tone signal amplification circuit 104 is transmitted through a tone decoder 107 and a ringing signal generation circuit 108 to generate a ringing tone from the speaker SPA, and also generates a voice from the audio signal amplification circuit 104d. From the handset 11 to the slave unit 200 by signal output
The configuration is such that the audio from the other side is output.

Further, the video signal transmitted from the slave device 200 side is outputted to the monitor TV after being amplified by the video signal (g-number amplifier circuit 109) through the parallel input circuit 105.

On the other hand, in the other intercom slave device 200, the signal from the microphone M is transmitted to the microphone signal Iv width circuit 201a of the modulation section 201.
The voice signal amplified by
A modulation circuit 201c that modulates a high frequency signal f2 serving as a second carrier with a ringing signal to the 0 side and a tone signal.
and a bandpass filter 20 that limits the frequency band of the output of the modulation circuit 201c and outputs it to the balanced input/output circuit 203.
] d, a demodulator 204 that demodulates the high-frequency signal sent from the base unit 100 side to extract an emergency tone signal and audio signal, and an emergency and a balanced input/output circuit 203 that manually inputs the high frequency signal output from the modulation section 201 and the video signal output from the television camera TVC through the video filter circuit 206, and outputs the high frequency signal to the demodulation section 204. , the high frequency signal of the balanced input/output circuit 203 is sent to the signal line l, and the modulated signal sent from the base unit 100 via the signal line l is transmitted to the internal power supply of the slave unit 200 and the TV via the balanced input/output circuit 203. A power supply separation circuit 207 for separating the power supply of the camera TVC, a current detection circuit 208 for detecting the power supply current sent as a constant current from the Y4 machine 100, a shunt regulator 209 for keeping the supply layer Lfg current constant, and the current It is equipped with a camera power switch 210 that controls 0N10FF of the power supply to the television camera TVC according to the signal of the detection circuit 208, and the modulation section 204:
The output signal from the microphone signal amplification circuit 201a that keeps the microphone signal constant and amplifies it to hell, and the tone signal generation circuit 2
02 and the audio/tone mixing circuit 201b.
These signals are used to modulate a high-frequency signal such that the second carrier is a high-frequency signal that can be distinguished from the first carrier on the vAW side. The section 204 includes a band pass filter 204a that limits the frequency band of the high frequency signal from the balanced input/output circuit 203, a demodulation circuit 204b that demodulates the high frequency signal, and separates the demodulated signal into a tone signal and an audio signal. Voice/tone separation circuit 2 for
04C, an audio signal amplification circuit 204d, and a tone signal amplification circuit 204e.

In such a base unit 100 and slave unit 200, the connection terminals TI and TG provided on the base unit 100 side and the connection terminals T2 and TG provided on the slave unit side are the core wire and shielded outer wire of the coaxial cable ρ, respectively. The configuration is such that video, audio, and other control signals necessary for information communication are multiplexed and transmitted between the two via this signal line ρ.

By the way, in a system with such a configuration, when the call button SW of the slave device 200 is operated, a tone signal is output from the tone signal generation circuit 202 of the modulation section 204, and the modulation circuit 201c uses this tone signal to output the second carrier f2. FM
Modulate. The modulated second carrier f2 is sent to the base unit 100 side via the balanced input/output circuit 203 and the coaxial cable l, and this FM modulated signal is sent to the base unit 100 side via the balanced input/output circuit 105 of the base unit 100. Decode: Add to A&I (304). When the demodulation circuit 104b performs FM demodulation, the voice/tone separation circuit 104C separates and outputs the tone signal, 1
- It is amplified by the tone signal amplification circuit 104e, coated with a signal corresponding to the tone signal by the tone decoder 107, and inputted to the calling signal generation circuit 108, which causes the speaker SPA on the base unit 100 side to ring as a calling signal.

In this way, the called parent [100 side] responds by using the handset H by ringing the speaker SPA, and in conjunction with picking up the Huntsera hH, a camera power control signal is manually input to the variable constant current power supply circuit 101. In order to supply power to the television camera TVC on the child device 200 side, its output current is switched to the maximum setting value.

Furthermore, the voice signal of the responding handset I is sent from the voice/tone mixing circuit 103a to the modulation circuit 103b, and is FM-modulated on the first carrier f1. The FM-modulated first carrier f1 is transmitted from the bandpass filter 103c to the slave device 200 side via the balanced input/output circuit 105 and the coaxial cable l.

On the other hand, in the slave device 200 that receives this signal, the signal is inputted to the demodulation circuit 204b through the balanced input/output circuit 203, the band pass filter 204a of the demodulation section 204, and the FM demodulation of the FM modulated wave of the first carrier is performed to produce audio. The signal is separated and outputted by the voice/tone separation circuit 204c, amplified by the voice signal amplification circuit 2゜4d, and sent to the speaker SP of the slave device 200.
B outputs the response from the base unit 100 side.

Also, is it certain that it will be transmitted from the base unit 100 down? The current is separated and outputted by the tR separation circuit 207, the current level is detected by the current detection circuit 208, and when the current level is at the maximum II current value, a signal is sent to the camera power switch 210, and the signal is sent to the camera power switch 210 through the shunt regulator 209. Power is supplied to the TVC.

When this television camera TVC is driven, the video signal is transmitted from the video filter circuit 206 to the balanced input/output circuit 203 and to the balanced input/output circuit 1 on the i-machine 100 side via the coaxial cable l.
05, the signal is amplified by the video signal amplification circuit 109 and sent to the monitor TV, where the video is displayed.

In addition, the voice signal manually input from the microphone M of the slave device 2001+L is amplified by the microphone signal amplification circuit 201a, and the tone signal and the voice/1.-
The mixture is mixed in the mixer circuit 201b and inputted to the modulation circuit 201c, where the second carrier is FM modulated, and the balanced input/output circuit on the 11m1oo side is transmitted through the bandpass filter 201d, the balanced input/output circuit 203, and the coaxial cable l. 10
After being demodulated, the signal is amplified by the audio signal amplification circuit 104d and outputted from the handset (2) of the base unit 100.

And in such a TV intercom system,
The first carrier f1 and the second carrier f2 are selected to have frequencies higher than the video signal frequency band of the television camera in order to prevent interference.

Figure 6 is a diagram showing the relationship between these frequencies, and shows the relationship between the DC voltage #i, the video signal having a frequency band of several MHz, and the main unit modulated wave by the first carrier fl at a frequency above that. The child device modulated waves by the second carrier f2 are set to different frequencies, and are multiplexed and transmitted through a dedicated signal line.

Further, FIG. 7 is a diagram showing the frequency relationship between the signals before modulation of the base unit modulated wave and the slave unit modulated wave. That is, the audio signal has a frequency band of approximately 10 Kl-1z, and the tone signal transmitted at the same time is set to 20 KHz, which is outside the audio signal band, to prevent interference.

By the way, in this type of TV intercom system, only a pair of signal lines β are required, so it has the feature of saving wires in terms of construction, but on the other hand, as the length of laying the signal line l increases, Since the resistance component increases, the power supply voltage and signal components transmitted in a superimposed manner are attenuated by the signal line β.

From this point of view, in conventional systems, power transmission from the base device 100 side to the slave device 200 side is changed from the base device 10
This is performed by a variable constant current power supply circuit 101 provided on the 0 side and a shunt regulator 209 provided on the child device 200 side, and a configuration is adopted in which a constant voltage is always supplied to the child device 200 side.

However, even when such measures are taken, the power supply voltage supplied to the variable constant current power supply circuit 101 of the base unit 100 is limited, so the length of the signal line r exceeds a certain value, resulting in transmission loss. Variable constant current power supply circuit 101
If a constant current cannot be maintained and the current transmitted to the slave unit 200 further decreases and the shunt current to the shunt regulator 209 is no longer flowing, the power supply voltage of the slave unit 200 will change depending on the current consumption. This will result in significant changes.

The simplest method to deal with such inconvenience is to limit the length of the signal line β within a specified value, but it is troublesome to set the length of the signal line to 1U11 when constructing the intercom system. Especially when installing using existing wiring, it is extremely difficult to measure the signal line, so the reality is that it is a trial and error process such as call tests after installing the intercom system. It is desired to develop a television intercom that can use a method to confirm whether the transmission loss in the signal line is within the specified value.

[Problems to be Solved by the Invention] The present invention, proposed to solve the above-mentioned problems, is capable of testing the intercom main unit by operating a test switch provided inside the intercom main unit when constructing an intercom system. It is an object of the present invention to provide a television intercom system that can provide guidance when laying a signal line by issuing an alarm when the current value supplied from a device to a slave device is less than a specified value.

[Means for Solving the Problems] The present invention proposed to achieve the above object connects an intercom base unit having a monitor television and an intercom slave unit having a monitor camera using a dedicated signal line. , a television intercom system ζcoo which multiplex transmits a video signal and an audio signal from the intercom slave device to the intercom m device, and an audio signal superimposed on TLR from the interphone base device to the interphone slave device. and the intercom base unit is on the intercom slave side,
A variable constant current power supply circuit for supplying constant current power with different values when the TV camera is being driven and not being driven, and a current value supplied from this variable constant current power supply circuit to the intercom slave side is the set value. a monitor circuit that determines whether or not the current value is greater than or equal to The configuration includes an alarm circuit that indicates an abnormal state when the monitor circuit determines that the value has decreased below the set value.

[Function] In the TV intercom system of the present invention, when the signal line ρ is wired during construction of the intercom system and the test switch provided on the main unit side is operated, the trigger circuit changes the power a setting of the variable constant current power supply circuit. The value is switched to the maximum current to be supplied to the child device and energization is performed. This supplied current is consumed by the slave unit through the signal line, returns again through the signal line, and is grounded at the base unit.This 'FL current value is converted into voltage by a resistor, and this voltage is converted into a reference voltage by the monitor circuit. When the current value is less than the specified value, an f-report is output from the alarm circuit.

[Example] The present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing the main configuration of the present invention, in which 1 indicates an intercom base unit, and 2 indicates an intercom slave unit.

This base unit 1 includes a trigger circuit 14 that switches the set current value of the variable constant current power supply circuit 11 to the maximum current value to be supplied to the slave unit 2, and a trigger circuit 14 that switches and sets the current value of the variable constant current power supply circuit 11 to the maximum current value supplied to the slave unit 2, and a trigger circuit 14 that switches the current value from the variable constant current power supply circuit 11 to the slave unit 2. A balun 15 that carries out balanced transmission to the device 2 side via the signal line l, a resistor RT that converts the return current from the signal line β into voltage, and an alarm when the voltage across the resistor R7 is below the reference voltage. A monitor circuit 12 that outputs a voltage to a circuit 13 is provided.

FIG. 2 shows an example of a circuit that further embodies the configuration shown in the block diagram of FIG. 1. In the figure, 11 is a variable constant current power supply circuit, 12 is a monitor circuit, 13 is a police officer circuit 14 is a trigger circuit, and 15 is a balun. To explain the operation according to the diagram, when the test switch SW is operated after the signal line of the intercom system has been installed, the relay Ry is energized from the power supply voltage E of the main unit L, and the relay Ry is connected to the variable constant current power supply circuit 11. At the same time, the relay contact ry switches from S contact to R contact, transistors Q3 and Q2 turn on, and Zener diode 1' Z D
A current is supplied to the transistor Q1, and the base-emitter voltage of the transistor Q1 becomes constant at the Zener voltage VD. Therefore, by setting the resistance values R1 and R2 to appropriate values, the current output through the transistor Ql can be adjusted to the relay contact r.
When y is connected to the S side, it becomes a low level constant current when the slave TV camera (not shown) is not driven, while when the relay contact ry is connected to the R side, , the high level constant Qt at which the television camera was driven
>-fz. Therefore, by operating the test switch, a high-level constant current is sent to the transmission line 1 through the balun 15 and the terminal T1, while the return current from the slave unit 2 is grounded through the terminal T2, the balun 15, and the resistor RT. In other words, from the main unit l to the signal line l, through the slave unit 2
1111 is converted into a voltage across the resistor R7, this voltage is compared with the base voltage VREF by the comparator CMP of the monitor circuit 12, and the resistor R is lower than the base voltage VREF.
When the voltage across resistor R7 is high, the output voltage of comparator CMP is at the rLJ level because the current value supplied to the child device has reached the specified value, but the voltage across resistor R7 is higher than the reference voltage VREF. If it is low, the current value supplied to the slave unit has not reached the specified value, so the comparator CM
The output voltage of P becomes rHJ level, the transistor Q4 of the alarm circuit 13 is driven, and the light emitting diode is energized through the resistor R5 to display the light.

Therefore, when constructing an intercom system, it can be immediately determined by operating the test switch SW whether the amount of current supplied from the parent unit to the slave unit has reached a specified value.

Although not shown in the circuit diagram of Fig. 2, the test switch SW has a handset (
A switch is connected in parallel to switch the camera to a constant current value when the power source is supplied in response to the pickup of the power source (not shown).

Next, FIG. 3 is a block diagram showing the configuration when the circuit as described above is incorporated into a conventional television interpon system. In the figure, parts that are the same as those in the conventional system are given the same numbers, and their explanations will be omitted. In this system, when the test switch is operated, the current value of the variable constant current ftR circuit is switched to a high level by the signal from the trigger circuit 14, and 1! It is sent out to the signal line l through the source superimposition circuit 106 and the balanced input/output circuit 15, and is supplied to the TV camera TVC and the internal power supply of the slave unit from the +, 1, and balanced human output 0 paths 21 on the slave unit side through the power separation circuit 1207. . On the other hand, the current supplied to the slave device 2 is 1ull from the balanced input/output circuit 21 via the signal line β.
The balanced input/output circuit 15 returns to the variable constant current power supply circuit 11, but the alarm circuit 1
3 will be driven.

[Effects of the Invention] According to the present invention, if the current supply to the slave unit falls below the specified value due to the length of the signal line laid during construction of the intercom system, it can be immediately determined, and the system is highly reliable. It becomes possible to provide a TV intercom system.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a block diagram of the configuration of the present invention, FIG. 2 is a specific example of the circuit, and FIG. 3 is a block diagram of the configuration of the present invention incorporated into a conventional system. FIG. 4 is an explanatory diagram of the conventional system configuration, FIG. 5 is a block diagram thereof, and FIG. 6 is a diagram showing the frequency relationship of signals multiplexed and transmitted on signal lines.
The figure is a diagram showing the frequency arrangement of audio signals and tone signals. [Explanation of symbols...Intercom base unit 2...Intercom slave unit 11...Variable constant current power supply circuit 12, 14, 13, TV, VC i-Umbrella...Monitor circuit...Trigger circuit...Alarm Circuit Board/Monitor TV...Monitor Camera/(Word line)

Claims (1)

[Claims] 1) An intercom base unit having a monitor TV and an intercom slave unit having a monitor camera are connected by a dedicated signal line, and a video signal is transmitted from the intercom slave unit to the interphone base unit. In a TV intercom system in which audio signals are multiplexed and transmitted from the intercom base unit to the intercom slave unit by superimposing the audio signals on a power supply, the intercom base unit transmits a drive signal to the intercom slave unit to drive a television camera. Is the current value supplied from this variable constant current power supply circuit to the above-mentioned intercom slave unit greater than or equal to the set value? a trigger circuit that switches the variable constant current power supply circuit to an output for driving the television camera; and a monitor circuit that determines whether the current value supplied from the variable constant current power supply circuit to the interphone slave side is A television intercom system characterized by comprising an alarm circuit that indicates an abnormal state when it is determined that the value has decreased below a set value.