JPH0416538Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a monitor control device for video calls, and in particular to a monitor control device for video calls that supplies a constant current to multiple dedicated TV cameras via coaxial cables. Regarding circuits.

[Technical Background of the Invention] Some conventional monitor control circuits for television communication devices have the following configuration. FIG. 2 shows an example of the configuration of a monitor control circuit of a television communication device that monitors and controls a television camera having three entrance slave units each having a built-in television camera. In FIG. 2, 1 is a constant current circuit. The output side of the constant current circuit 1 is the relay AY, BY contacts ay ₁ , ay ₂ , by ₁ , by ₂
Connected to coaxial cable COX ₁ ~ COX ₃ via. Relay AY is the terminal of shift register 2,
Qb, Qc, OR circuit 12 and transistor 14
The shift register 2 is connected through the terminal Qb or Qc of the shift register 2, and is configured to operate when the terminal Qb or Qc of the shift register 2 becomes H level. Relay BY is connected to terminal Qc and transistor 13
The shift register 2 is connected to the shift register 2 through the terminal Qc, and is configured to operate when the terminal Qc of the shift register 2 becomes H level. The terminal Qd of the shift register 2 is connected to the terminal Q of the monostable multivibrator 3 and the terminal via the OR circuit 10.
It is connected to RS, and the monostable multivibrator 3 and OR circuit 10 constitute a reset circuit. Also,
The terminal of monostable multivibrator 3 is timer 5.
Connect to terminal R of. The video monitor switch 6 is connected to the monostable multivibrator 4, and the terminals and Q of the monostable multivibrator 4 are connected to the terminal S of the timer 5 and one input side of the OR circuit 9, respectively. Terminal CA of timer 5 is terminal C of constant current circuit 1,
Input side of inverter 16, one input side of AND circuit 8, and TV monitor startup circuit (not shown)
Connect with. The output side of the OR circuit 9 is connected to the other input side of the AND circuit 8, and the output side of the AND circuit 8 is connected to the terminal C of the shift register 2. The output side of the inverter 16 mentioned above is connected to the base of the transistor 15 via a resistor 15b. Further, the emitter of the transistor 15 is connected to the power supply (+), and the collector is connected to one coil of the relays AY and BY. Shift register 2 terminal
Qa, Qb, and Qc are each connected to the input side of the NOR circuit 7. The output side of the NOR circuit 7 is connected to the terminal D of the shift register 2 and the other input side of the OR circuit 9.

In the monitor control circuit of the television communication device having the above configuration, when the video monitor switch 6 is pressed once when all the circuits are in the initial state, the monostable multivibrator 4 is activated. When the monostable multivibrator 4 operates, a single pulse at the H level is output from the terminal Q to one input side of the OR circuit 9, and a single pulse at the L level is output from the terminal to the terminal S of the timer 5.
This L level single pulse becomes a set signal for the timer 5. The width of this single pulse is determined by the resistor 4a and capacitor 4b connected to the terminals T ₁ and T ₂ .
Timer 5 receives an L level set signal at terminal S and enters the set state. When timer 5 is set, inverter 16, resistor 15b, transistor 1
The transistor 15 operates by connecting the base of the transistor 5. It also sends a start signal to the television monitor start circuit. Since the other input side of the AND circuit 8 is connected to the terminal Q of the monostable multivibrator 4 and one input side of the OR circuit 9, it is at H level. When the terminal CA becomes H level, an AND logic is formed and a shift pulse is sent to the terminal C of the shift register 2. Since the first shift pulse is input to the terminal C of the shift register 2, the terminal Qa becomes H.
level. Even if terminal Qa becomes H level, relays AY and BY do not operate, but timer 5 terminal CA
Since the constant current circuit 1 is activated via the constant current circuit 1, a constant current is supplied to the coaxial cable COX ₁ . Next, when the video monitor switch 6 is pressed for the second time, the shift register 2 has terminal Qa at L level and terminal Qb at H level.
level. When terminal Qb becomes H level, relay AY operates and contacts ay ₁ and ay ₂ connect the coaxial cable.
The constant power supply being supplied to COX ₁ is switched to the coaxial cable COX ₂ . Similarly, for the third operation, the terminal
Qc becomes H level. When terminal Qc becomes H level, relay BY operates. Relay AY continues to operate via OR circuit 12, so the coaxial cable
The constant current being supplied to COX ₂ is switched to the coaxial cable COX ₃ . In this way, when the fourth shift pulse is input to the terminal C, the terminal Qd becomes H level. When the terminal Qd becomes H level, the terminal A of the monostable multivibrator 3 becomes H level.
The monostable multivibrator 3 operates when terminal A becomes H level, terminal Q becomes H level, and terminal Q becomes L level. Due to the operation of the monostable multivibrator 3, the timer 5 is reset by the connection between the terminal and the terminal R of the timer 5. Furthermore, since the terminal Q becomes H level, the shift register 2 receives a reset signal via the OR circuit 10 at the terminal RS, so that the terminal Qd, which has become H level, becomes L level. Since the terminal Qd becomes L level, the shift register 2 is initialized. On the other hand, timer 5
When is reset, the activation signal to the television monitor activation circuit and the constant current circuit 1 is stopped, the television monitor becomes inactive, and the constant current circuit 1 stops supplying constant current. Also, terminal CA of timer 5 and inverter 1
The connection to the base of transistor 15 through 6 turns transistor 15 off and the relay
Cut off the power to the AY and BY coils. In this way, the entire monitor control circuit of the television communication device is restored. Furthermore, when the fifth operation is performed, the operation returns to the first operation, and the following video monitor switch 6
Repeat the above operation each time you press .

[Problems with the prior art] As explained above, the monitor control circuit of the conventional video communication device sequentially switches and supplies constant current output from one constant current circuit to the coaxial cables COX ₁ to COX ₃ . When connecting only a surveillance TV camera as shown in Figure 3, the TV camera VDC ₁ must have specifications that operate under the same conditions as the TV camera VDC ₂ built into the entrance cordless unit, as shown in Figure 4. A special television camera was required. However, since there is no such unified standard, there are restrictions on the TV cameras that can be connected.
As shown in the figure, the general-purpose TV camera VDC ₃ , which operates on its own power supply, cannot be used either. For this reason, it has the disadvantage that it is necessary to prepare various television cameras that match the interface conditions of the company in which the constant current superimposed on the coaxial cable is supplied with power by the constant current constant voltage converter 19.

[Purpose of the invention] The present invention has been made in view of the above-mentioned points, and an object thereof is to provide a monitor control circuit for a television communication device that can be applied to a dedicated television camera and a general-purpose television camera.

[Summary of the invention] The monitor control circuit of the video communication device according to the invention includes a plurality of dedicated TV cameras built in a doorway handset, a video monitor switch, and a monitor control circuit for controlling the video communication device according to the operation of the video monitor switch. power supply means for supplying a constant current for video to one of the television cameras via a coaxial cable, and replacing any number of the plurality of dedicated television cameras with general-purpose television cameras; This configuration includes a power cutoff switch that is specified and turns off the supply of the video constant current to the number of coaxial cables corresponding to the specified number.

[Embodiment of the invention] Hereinafter, an embodiment of the video communication device of the invention will be described in detail with reference to FIG.

Components that are the same in FIG. 1 and FIG. 2 are designated by the same reference numerals, so their explanation will be omitted.

The monitor control circuit of the TV communication device according to the present invention is roughly divided into a constant current circuit 1 as a power supply means for supplying a constant current for video, and a general-purpose TV camera replacing any number of dedicated TV cameras. , a power cut-off switch SW that specifies the number of general-purpose TV cameras and cuts off the constant current for video to the coaxial cables corresponding to the specified number, and contacts ay 1 and ay ₂ on the coaxial cables COX ₁ to COX _{2 .} , by ₁ ,
Relays AY, BY supplying constant current output from constant current circuit 1 via ₂ , relays AY,
It is set by a shift register 2 that controls BY, a monostable multivibrator 4 that generates a single pulse in response to the operation of the video monitor switch 6, and an L level single pulse output from the terminal Q of the monostable multivibrator 4. and an OR circuit 9 into which the H level single pulse output from the terminal Q of the monostable multivibrator 4 is input to one input side.
When timer 5 is set, one input goes high.
AND circuit 8 whose other input becomes H level when the output side of OR circuit 9 becomes H level, and a shift pulse which is inputted to terminal C when the AND logic of AND circuit 8 is formed. Consists of register 2. Also, shift register 2
A monostable multivibrator 3 and a transistor 15 are provided, which operate when the terminal Qd of the terminal becomes H level. The monostable multivibrator 3 is a circuit that initializes the monitor control circuit of the TV communication device, and when the terminal Q becomes H level, the shift register 2
A reset signal is sent to the terminal RS of the timer 5 via the OR circuit 10, and when the terminal Q becomes L level, the reset signal is sent to the terminal R of the timer 5.
Configure it to output a reset signal. Also,
The aforementioned transistor 15 is a switch that operates via an inverter 16 and a resistor 15b when the timer 5 is set, and supplies power to the relays AY and BY.

Power cutoff switch SW has movable contact Pk and fixed contact
It has P ₀ , P ₁ , P ₂ , and P ₃ , and when the movable contact Pk is rotated, one of the fixed contacts P ₀ , P ₁ , P ₂ , and P ₃ is selected.
The movable contact Pk is connected to the terminal VB of the constant current circuit 1. Further, the fixed contact P ₀ is connected to the switching contact of the contact ay ₁ of the relay AY. Fixed contact P ₁ is connected to switching contact of contact by ₁ of relay BY. Fixed contact _P2 is connected to the fixed contact on the normally open contact side of contact by ₁ of relay BY. The supply of constant current to the coaxial cables COX ₁ , COX _{2 , COX 3 is determined by the combination of operation and recovery of the contacts ay 1 , by 1 and the contacts} ay ₂ , by ₂ on the reference potential point side. When the power cutoff switch SW, which cuts off the constant current for video, is in the fixed contact _P0 position, the number of general-purpose television cameras is 0. In the position of fixed contact _P1 , the number of general-purpose television cameras is one.
Similarly, in the position of the fixed contact _P3 , the number of general-purpose television cameras is three.

[Operation of the invention] In the above configuration, as an example, a coaxial cable is used.
The case where the general-purpose television camera VDC ₃ shown in FIG. 5 is connected to COX ₁ will be explained. In this case, the power cutoff switch SW is set to the fixed contact _P1 position. When the video monitor switch 6 is pressed once, the terminal Q of the monostable multivibrator 4 generates a single pulse of H level, and the terminal Qa of the shift register 2 becomes H level. In this state, relays AY and BY do not operate as described above. Furthermore, the constant current circuit 1 is activated by the set operation of the timer 5,
Outputs constant current to terminal VB. However, since the power cutoff switch SW is in the fixed contact _P1 position, no constant current is supplied to the coaxial cable _COX1 .
In the second and third operations of the video monitor switch 6, the coaxial cables COX ₂ and COX ₃ are selected by the operation of the shift register 2, as in the past, and in the fourth operation, the shift register 2 is reset, and at the same time the timer is activated. 5 is also reset, so the monitor control ends.

Next, when connecting the general-purpose TV camera VDC ₃ to the coaxial cables COX ₁ and COX ₂ , turn off the power supply switch.
Set the SW to the fixed contact _P2 position. Then, operate the video monitor switch 6 to turn on the relay.
Even if the AY and BY contacts switch, the coaxial cable
Constant current is not supplied to COX ₁ and COX ₂ .

In addition, if you connect a general-purpose TV camera to the coaxial cable COX ₁ , COX ₂ , COX ₃ , turn off the power switch.
Set the SW to the fixed contact _P3 position.

Conversely, if no general-purpose television camera is connected, set the power cutoff switch SW to the fixed contact _P0 position.

In the above embodiment, a power cutoff switch SW is provided at the terminal VB on the constant current supply side, but a power cutoff switch SW consisting of three sets of normally open contacts is provided, and one side of each normally open contact is directly connected to the coaxial cable COX ₁ ,
It may be connected to COX ₂ and COX ₃ , and the other normally open contact side may be collected and connected to the terminal VB of the constant current circuit 1.

In the above embodiment, the number of coaxial cables is three, but the number is not limited to three.

[Effects of the invention] The monitor control circuit of the video communication device according to the invention includes a plurality of dedicated TV cameras built into a doorway handset, a video monitor switch, and a monitor control circuit for controlling the video communication device according to the operation of the video monitor switch. power supply means for supplying a constant current for video to one of the television cameras via a coaxial cable, and replacing any number of the plurality of dedicated television cameras with general-purpose television cameras; The configuration is equipped with a power cutoff switch that cuts off the supply of the constant current for video to the number of coaxial cables corresponding to the specified number, so it can be used with general-purpose TV cameras or dedicated TV cameras with different interfaces. The feature is that it does not supply power to television cameras that do not need to be supplied with current. Therefore, there is an effect that there is no need to develop many types of dedicated television cameras.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a monitor control circuit of a video communication device according to the present invention, FIG. 2 is a block diagram of a monitor control circuit of a conventional video communication device, and FIGS. 3, 4, and 5 The figure is a block diagram of the entrance slave unit according to FIGS. 1 and 2. 1... Constant current circuit (power supply means), 2... Shift register, 6... Video monitor switch, SW
...Power cut-off switch.

Claims (1)

[Scope of utility model registration request] A plurality of dedicated TV cameras built into the entrance cordless handset, a video monitor switch, and video settings are sent to one of the plurality of dedicated TV cameras via a coaxial cable in accordance with the operation of the video monitor switch. In the monitor control circuit of a television communication device equipped with a power supply means for supplying current, an arbitrary number of the plurality of dedicated television cameras is replaced with a general-purpose television camera, and the number of the general-purpose television cameras is specified. A monitor control circuit for a television communication device, comprising a power cutoff switch that cuts off the supply of the constant current for video to a number of coaxial cables corresponding to the number of coaxial cables.