JPH0897920A - Two-wire video interphone system - Google Patents

Abstract

PURPOSE: To realize the 2-wire video interphone system in which no popup noise is generated at start and end of a speech in a intercom slave set with a camera. CONSTITUTION: An interphone master set A replies a call from an intercom slave set B and makes a speech together with monitoring, intercom then outputs of a speaker SPb and a microphone MIb of the slave set B are mute-processed for times between a time (t) at start of the speech and a time t' at end of the speech.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-wire television intercom system in which a pop sound is prevented from being generated at the beginning and end of a call when a call is made to an intercom slave with a camera by means of an intercom master.

[0002]

2. Description of the Related Art In a conventional two-wire type TV intercom system, when an intercom base unit with a camera calls an intercom base unit with a monitor TV through a two-wire signal line, the intercom base unit supplies a camera power source to the intercom slave unit. It is possible to supply and supply a call between the intercom master unit and the intercom slave unit, and display the image captured by the camera of the intercom slave unit on the monitor TV of the intercom master unit.

FIG. 5 is a diagram showing an example of a change in the line voltage that occurs in the two-line signal line in this case. The intercom base unit detects a call from the intercom subunit when the line voltage of the two-wire signal line drops from 6V in the standby state to the ground level. When the handset is lifted or the operation of the call start button is detected in response to this call, the intercom base unit supplies 15V camera power to the intercom subunit, drives the camera of the intercom subunit, and receives the video signal. In addition to displaying images on the monitor TV, it is possible to talk by sending and receiving audio signals.

[0004]

However, the above-mentioned conventional method 2
In the line-type TV intercom system, the line voltage of the 2-line type signal line fluctuates greatly between the standby state and the call state, so a pop sound is heard from the speaker of the intercom subunit at the beginning and end of the call, and the visitor is not able to hear it. It was making me feel good.

The present invention has been proposed in order to solve the above-mentioned problems, and an object thereof is a two-wire system in which a pop sound is prevented from being generated at the beginning and end of a call in a door intercom with a camera. It provides a TV intercom system.

[0006]

A two-wire television intercom system according to claim 1, which is proposed to achieve the above object, responds to a call from an intercom subunit and responds with an intercom master unit to make a call. When making the call, the outputs of the speaker and the microphone of the intercom subunit are muted for a predetermined time at the start and end of the call.

The two-wire type television intercom system according to claims 2 to 4 is characterized by means for detecting the start and end of a call and performing mute processing. 2 according to claim 2
In the line-type television intercom system, the intercom base unit is provided with a power supply control circuit that supplies power to the intercom subunit, while the intercom subunit is a voltage that monitors the power supply voltage supplied from the 2-wire signal line. The configuration includes a monitoring circuit and a mute control circuit that mutes the output of the microphone and the speaker when the voltage monitoring circuit determines that the power supply voltage supplied from the two-wire signal line is at the intermediate voltage level. ing.

In the two-wire type TV intercom system according to the third aspect, the intercom base unit is provided with a mute signal generating circuit for sending a mute signal to the intercom subunit through the two-wire signal line, while the intercom subunit is provided. Has a configuration including a mute signal detection circuit for detecting a mute signal transmitted through the two-wire signal line, and a mute control circuit for muting the output of the microphone and speaker of the intercom subunit. There is.

In a two-wire television intercom system according to a fourth aspect, a mute modulation circuit for modulating and transmitting a mute signal having a frequency exceeding the audible range to an intercom child unit through a two-wire signal line in an intercom base unit. One of the intercom sub units has a mute detection circuit for demodulating the modulated mute signal transmitted through the two-wire signal line, and a mute for muting the microphone and speaker output of the intercom sub unit. It has a configuration including a control circuit.

The two-wire television intercom system according to the fifth and sixth aspects is characterized by the mute processing by the mute control circuit.
The configuration is such that the amplification degree of the amplification circuit added to the microphone and the speaker is gradually increased and decreased.

[0011]

According to the television intercom system of the first aspect, in response to a call from the intercom subunit, when the intercom master responds and a call is made, a predetermined time is provided between the start and end of the call. , The output of the speaker and microphone of the intercom subunit is muted, so no pop sound is generated.

According to the two-wire type TV intercom system of the second aspect, the power supply control circuit of the intercom base unit is in a standby voltage of a predetermined level in a standby state when a call is not made between the intercom slave unit and the intercom base unit. Is supplied to the two-wire signal line, and when the intercom base unit responds to the calling operation from the intercom slave and when the intercom base unit restores the handset, the level is higher than during standby and during call A power supply of an intermediate voltage level smaller than the above is supplied to the two-wire signal line for a predetermined time, and in one of the intercom subunits, the power supply voltage supplied from the two-wire signal line in the voltage monitoring circuit becomes the intermediate voltage level. When this is detected, the mute control circuit is activated to mute the output of the microphone and speaker.

According to the two-wire television intercom system of the third aspect, the mute signal generating circuit of the interphone master unit responds to the calling operation from the intercom slave unit when the intercom master unit responds, and when the intercom master unit. When the machine returns the handset, it sends a mute signal to the intercom subunit via the 2-wire signal line, and one of the intercom subunits detects the mute signal sent from the 2-wire signal line by the mute signal detection circuit. When it is detected, the mute control circuit is activated to mute the output of the microphone and speaker.

According to the two-wire television intercom system of claim 4, when the mute modulation circuit of the interphone master unit responds to the calling operation from the intercom slave unit and when the interphone master unit responds. When the handset returns from the handset, it modulates and sends out a mute signal with a frequency exceeding the audible range to the intercom subunit through the two-wire signal line. On the other hand, in the intercom subunit, when the mute detection circuit demodulates and detects the modulated mute signal sent through the two-wire signal line, the mute control circuit is activated to mute the output of the microphone and speaker. Let

According to the two-wire television intercom system of the fifth and sixth aspects, the mute control circuit gradually increases or decreases the amplification degree of the power source of the microphone or speaker, or the amplification circuit added to the microphone or speaker. By doing so, mute processing is performed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. [Embodiment 1] FIG. 1 is a block diagram showing a configuration example of a two-wire television intercom system according to the present invention.

In the figure, B is an intercom subunit with a camera installed at the entrance, and A is an intercom master unit with a monitor TV installed in the room, which is connected by a two-wire signal line L. Intercom base unit A has intercom subunit B
I / F circuit 1 for transmitting and receiving signals and F
Through the FM modulation circuit 2 and the FM demodulation circuit 3 for M-modulating and demodulating, the monitor circuit 4 for displaying an image on the monitor TV MO, the internal power supply of the intercom base unit A, and the two-wire signal line L, the intercom child Internal power supply for device B and camera C
1, a power supply control circuit 5 for supplying camera power, a call detection circuit 6 for detecting a call from the intercom sub unit B, and a control processing unit 7 including a microcomputer (CPU) for controlling each of these units.

One of the intercom sub-units B, like the intercom main unit A, has an I / F circuit 11, an FM modulation circuit 12, and an F modulation circuit 12, F.
A camera circuit 14 for driving the camera C, a voltage monitoring circuit 15 for monitoring the power supply voltage supplied via the two-wire system signal line L, a microphone MIb of the intercom sub-unit B, and a speaker SPb. It has a mute control circuit 16 for muting the output of and a call button 17.

With the above structure, an audio signal is transmitted from the intercom master unit A to the intercom slave unit B through the two-wire signal line L, while a video signal and an audio signal are transmitted from the intercom slave unit B to the intercom master unit A. However, at this time, a signal in which a video signal and an audio signal are superimposed on the power supply voltage is transmitted and received between the intercom master unit A and the intercom slave unit B. Audio signals are transmitted and received as FM modulated waves with different frequencies.
A simultaneous call is realized using the microphones MIa and MIb and the speakers SPa and SPb. Here, the intercom slave unit A and the intercom master unit B realize an simultaneous simultaneous call, so that the intercom slave unit B side FM modulation circuit 12 and FM demodulation circuit 13 and the intercom master unit A side FM demodulator circuit are provided. 3, F
The frequencies F1 and F2 of the carriers of the M modulation circuit 2 are common. Also, the video signal is transmitted in the baseband, and the video projected by the camera C is displayed on the monitor TV MO.
Is projected on.

Next, the basic operation of the present invention will be described with reference to the change in line voltage that occurs in the two-wire signal line L in FIG. The power supply control circuit 5 of the intercom base unit A sets a standby voltage of a predetermined level (for example, 6 V) to 2 when the intercom base unit A and the intercom base unit A are in a standby state without a call.
The signal is supplied to the linear signal line L. Call button 16 of the doorphone subunit B
When is operated, the line voltage of the two-wire type signal line L decreases from the standby state to the ground level, so the call detection circuit 6 of the intercom master unit A detects this state and notifies the control processing unit 7. In response to this, the control processing unit 7 tells the power supply control circuit 5 a predetermined time t of, for example, 0.5 seconds to 1 second, which is longer than the standby time (6V) and is in a call (for example, 15
Intermediate voltage level (eg 10
The power of V) is supplied to the two-wire signal line L. here,
The power source of the intermediate voltage level is output when the call from the intercom subunit B is detected, but may be output when the call start button is operated after the call is detected.

On the other hand, in the intercom sub-unit B, the voltage monitoring circuit 15 constantly monitors the power supply voltage supplied through the two-wire type signal line L, and the power supply voltage is at an intermediate voltage level (10 V). When the determination is made, the mute control circuit 16 is operated to mute the outputs of the microphone MIb and the speaker SPb of the intercom subunit B. Then, after the lapse of the predetermined time t, the intercom base unit A raises the line voltage of the two-wire type signal line L to the level (15 V) at the time of a call by the power supply control circuit 5, and the camera C of the intercom subunit B. Supply power to. As a result, the camera C is driven, and the video signal is output from the camera C via the camera circuit 14 and 2
It is sent out through the linear signal line L and is displayed as an image on the monitor television MO through the monitor circuit 4. Naturally, at this time, the intercom master unit A and the intercom slave unit B can talk with each other.

At the end of the call, as in the case of the start of the call, when the return (on-hook) of the handset (not shown) of the intercom base unit A is detected, the power supply control circuit 5 causes the intermediate voltage for a predetermined time t '. 2 level (10V) power supplies
The signal is supplied to the line signal line L, and the voltage monitoring circuit 15 of the intercom sub-unit B detects the power supply voltage of the intermediate voltage level (10 V), operates the mute control circuit 16, and outputs the microphone MI.
b, the output of the speaker SPb is muted.

As described above, according to the above-mentioned two-wire intercom system, the output level of the audio signal to the microphone MIb and the speaker SPb is lowered by the mute process during a predetermined time t and t ′ at the start and end of the call. Because
I can't hear the pop sound like "bop". Here, the microphone MIb of the intercom slave B and the speaker SPb
Although only the mute processing to the intercom has been described, as shown in FIG. 1, the intercom master unit A side similarly performs the microphone MIa and the speaker S for a predetermined time at the start and end of the call.
It is desirable to mute the output of Pa.

[Second Embodiment] Next, another embodiment will be described. FIG. 3 is a block diagram showing a configuration example of a two-wire television intercom system in this embodiment. Figure 3
The configuration of is similar to that of FIG. 1, but the intercom base unit A
1 is provided with a mute signal generation circuit 8 in addition to the configuration of FIG. 1, and the intercom subunit B is provided with a mute signal detection circuit 18 instead of the power supply monitoring circuit 15.

The basic operation of this embodiment is similar to that of the two-wire television intercom system described in the first embodiment, but the microphone MIb of the intercom subunit B and the speaker SP are used.
The operation of muting the output of b is different. The power supply control circuit 5 of the intercom base unit A detects the call from the intercom slave unit B as in the conventional case, and then the intercom slave unit B
Supply the level power to the call.

When there is a calling operation from the intercom slave unit B, the control processing unit 7 of the intercom master unit A causes the mute signal generation circuit 8 to send a mute signal to the intercom slave unit B through the two-wire signal line L. . The mute signal in this case may be a predetermined high frequency signal in addition to the pulse signal for changing the voltage level supplied on the two-wire type signal line L.

On the other hand, in the intercom subunit B, the mute signal detecting circuit 18 detects the mute signal, and the mute control circuit 16 detects the mute signal for a predetermined time.
The outputs of the microphone MIb and the speaker SPb are muted. Similarly, at the end of the call, when the return of the handset of the intercom master unit A is detected, the mute signal generation circuit 8 of the intercom master unit A sends a mute signal, and the mute signal detection circuit 18 of the intercom slave unit B mutes the mute signal. When the signal is detected, the mute control circuit 16 mutes the outputs of the microphone MIb and the speaker SPb.

[Third Embodiment] Next, still another embodiment will be described. FIG. 4 is a block diagram showing a configuration example of the two-wire television intercom system in this embodiment.
The configuration of FIG. 4 is almost the same as that of FIG. 3, but the intercom base unit A is provided with a mute modulation circuit 9 instead of the mute signal generation circuit 8, and the intercom slave unit B is muted instead of the mute signal detection circuit 18. A detection circuit 19 is provided.

The mute modulation circuit 9 is a circuit for modulating and transmitting a mute signal having a frequency exceeding the audible range to the intercom subunit B through the two-wire type signal line L, and the mute detection circuit 19 is a two-wire type signal line L. Is a circuit that demodulates the modulated mute signal transmitted through. The basic operation in this embodiment is similar to that of the two-wire type TV intercom system described in Embodiment 2, but there is a difference in the mute signal sent from the intercom master unit A to the intercom slave unit B.

When a calling operation is made from the intercom slave unit B, the control processing unit 7 of the intercom master unit A causes the mute modulation circuit 9 to transmit the intercom slave unit B through the two-wire signal line L to a frequency exceeding the audible range. Modulates the mute signal and sends it out. On the other hand, in the intercom subunit B, the mute detection circuit 19
Then, the modulated mute signal is demodulated and detected, and the mute control circuit 16 mutes the outputs of the microphone MIb and the speaker SPb of the intercom subunit B for a predetermined time. At the end of the call, as in the first and second embodiments, it is detected by the return of the handset of the intercom master unit A, and the same processing as at the start of the call is performed.

In this embodiment, since the mute signal is composed of a signal exceeding the audible range, it is demodulated and cannot be heard by the human ear even when output from the speaker. Therefore, the camera can be driven and stopped in a silent state. . The operation for operating the mute control circuit 16 has been described above in the first to third embodiments. Next, the mute processing performed by the mute control circuit 16 will be described.

There are two methods for mute processing. One is to gradually increase the power of the microphone MIb and the speaker SPb,
The method is to reduce the number, the other is the microphone MIb,
This is a method in which the amplification degree of an amplifier circuit (not shown) added to the speaker SPb is gradually increased or decreased. At the start of a call, the amplification degree of the power supply or the amplification circuit is increased, and at the end of the call, the amplification degree of the power supply or the amplification circuit is decreased to gradually change the output level of the audio signal to the microphone MIb and the speaker SPb. Is.

[0033]

As described above, the first aspect of the present invention is as follows.
According to the two-wire type TV intercom system described in any one of 6 to 6, since the pop sound is not heard in the intercom subunit at the start and end of the call, the visitor is not made uncomfortable. Particularly, in the two-wire type TV intercom system according to claim 4, since the signal having the frequency exceeding the audible range is used as the mute signal, even if demodulated and output from the speaker, it cannot be heard by the human ear, so that the visitor, etc. On the other hand, since it is not known that the camera is on / off controlled, the camera power can be supplied and driven in an ideal state.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example (Embodiment 1) of a two-wire television intercom system of the present invention.

FIG. 2 is a diagram showing an example of a change in line voltage generated in a two-wire signal line of a two-wire television intercom system according to the present invention.

FIG. 3 is a block diagram showing another configuration example (Example 2) of the two-wire television intercom system of the present invention.

FIG. 4 is a block diagram showing another configuration example (third embodiment) of the two-wire television intercom system of the present invention.

FIG. 5: 2 of a conventional 2-wire type TV intercom system
It is a figure which shows an example of the change of the line voltage which arises in a linear signal line.

[Explanation of symbols]

 A Intercom master unit with monitor TV B Doorphone subunit with camera L 2 wire type signal line 2,12 FM modulation circuit 3,13 FM demodulation circuit 5 Power supply control circuit 7 Control processing unit 8 Mute signal generation circuit 9 Mute modulation circuit 15 Voltage Monitoring circuit 16 Mute control circuit 18 Mute signal detection circuit 19 Mute detection circuit C Camera MO Monitor TV MIa, MIb Microphone SPa, SPb Speaker t, t'Mute processing time

Claims (6)

[Claims] 1. An intercom master unit with a camera installed at a front door and an intercom master unit with a monitor TV installed in a room are connected by a two-wire signal line, and the intercom master is connected through this two-wire signal line. The camera power is supplied from the device to the intercom slave unit, a call is made between the intercom slave unit and the intercom master unit, and the image captured by the camera of the intercom slave unit is displayed on the monitor TV of the intercom master unit. 2 In the line-type television intercom system, when the intercom master unit answers the call of the intercom slave unit and makes a call, a speaker and a microphone of the intercom slave unit are set for a predetermined time at the start and end of the call. 2-wire type TV intercom system configured to mute the output of. 2. The two-wire television intercom system according to claim 1, wherein the intercom master unit includes a power supply control circuit for supplying power to the intercom subunit through the two-wire signal line. The control circuit supplies a standby voltage of a predetermined level to the above-mentioned two-wire signal line during a standby state when no call is made between the intercom slave and the intercom master, while the intercom master responds to a call operation from the intercom slave. When the device responds and when the intercom base unit returns the handset, a power supply of an intermediate voltage level that is higher than during standby and lower than the level during communication is supplied to the 2-wire signal line for a predetermined time. In the intercom subunit, the voltage monitoring circuit for monitoring the power supply voltage supplied from the 2-wire type signal line and the voltage monitoring circuit are 2-wire type. When the power supply voltage supplied from the Line is determined to be in the intermediate voltage level, two-wire television interphone system and structure provided with a mute control circuit to mute the intercom slave unit microphone, the output of the speaker. 3. The two-wire television intercom system according to claim 1, wherein the intercom base unit includes a mute signal generation circuit for sending a mute signal to the intercom subunit through the two-wire signal line, This mute signal generation circuit sends a mute signal to the intercom slave unit through the above two-wire signal line when the intercom master unit responds to the calling operation from the intercom slave unit and when the intercom master unit returns the handset. The mute signal detecting circuit for detecting the mute signal transmitted through the two-wire signal line, and the mute signal detected by the mute signal detecting circuit , A mute control circuit for muting the microphone of the intercom subunit and the output of the speaker 2-wire TV intercom system. 4. The two-wire type TV intercom system according to claim 1, wherein the intercom master unit modulates and outputs a mute signal having a frequency exceeding an audible range to the intercom subunit through the two-wire type signal line. It is equipped with a mute modulation circuit. This mute modulation circuit uses the above-mentioned two-wire signal line when the intercom base unit responds to the calling operation from the intercom slave and when the intercom base unit returns the handset. And a mute detection circuit for demodulating the modulated mute signal transmitted through the two-wire signal line. The mute signal detected by this mute detection circuit mutes the output of the microphone and speaker of the intercom subunit. A two-wire type TV intercom system with a control circuit. 5. The two-wire television intercom according to claim 1, wherein the mute processing by the mute control circuit is performed by gradually increasing or decreasing the power supply of the microphone and the speaker for a predetermined time. system. 6. The mute processing by the mute control circuit is performed by gradually increasing or decreasing the amplification degree of an amplifier circuit added to a microphone or a speaker for a predetermined time. 2-wire TV intercom system.