JP3182767B2 - Video signal switching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal switching device, and more particularly to a video signal switching device suitable for use as a switching device for a monitoring video camera.

[0002]

2. Description of the Related Art Conventionally, when video cameras for monitoring are installed at a plurality of locations, it is conceivable that monitor receivers are provided by the number of video cameras and each monitor receiver receives an image at each monitoring location. As the number of places to be monitored increases, the number of monitor receivers together with the video cameras increases, and there is a problem that the configuration of the monitoring system becomes complicated. Also, when a video tape recorder (VTR) records a video signal obtained by a video camera for monitoring instead of a monitor receiver, the number of VTRs increases as the number of places to be monitored increases. And the configuration of the monitoring system becomes complicated.

For this reason, a video signal switching device for a surveillance camera which switches video signals supplied from video cameras for monitoring installed at a plurality of locations and selectively supplies the video signals to one monitor receiver has been put to practical use. .

This video signal switching device for a surveillance camera is such that, for example, video signals supplied from a plurality of connected video cameras for monitoring are sequentially switched at predetermined intervals and supplied to one monitor receiver. It is. By using this video signal switching device, the observer can monitor all places simply by watching the video displayed on one monitor receiver, and the configuration of the monitoring system can be simplified. In addition, the observer can easily perform monitoring. Also, when a video signal obtained by shooting by a monitoring video camera is recorded on a VTR, the video signal switching device can efficiently record the video signal on one VTR.

[0005]

However, this type of video signal switching device for a surveillance camera is limited to video cameras that can be connected by one switching device. For example, eight video cameras can be connected by one switching device. If monitoring is possible with more than eight video cameras when the connection can be made up to two, it is necessary to use two or more switching devices. In this case, if a monitor receiver or VTR is connected to each switching device, the number of necessary monitor receivers or VTRs increases, and the system configuration becomes complicated. For this reason, a plurality of switching devices are operated in conjunction with each other to provide one monitor receiver or VTR.
It is conceivable that monitoring can be performed by a computer, but in order to operate a plurality of switching devices in an interlocked manner, it is necessary to perform control using a computer device such as a personal computer. In
It is necessary to create a program for performing the switching control in advance and set the program in the computer device, which is troublesome and costly.

An object of the present invention is to make it possible to link a plurality of video signal switching devices with a simple configuration.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a video signal switching device for switching and outputting video signals supplied from a plurality of video signal sources.
0,300 °), a predetermined one video signal switching device (100) is set as a master, and the other video signal switching devices (200, 300 °) are set as slaves.
Within one vertical cycle of the video signal supplied from the video signal source,
Between the master video signal switching device (100) and all the slave video signal switching devices (200, 300 °),
The two-way communication is performed.

[0008] The present invention, in the video signal switching apparatus for outputting by switching the video signal supplied from a plurality of video signal sources, the master video signal by operating the predetermined setting means
Other video signal switching device that operates as a switching device and is connected
The device automatically operates as a slave video signal switching device when a command is received from the device.

[0009]

With this arrangement, when a plurality of video signal switching devices are connected, communication of control signals is performed between the master video signal switching device and the slave video signal switching device, and the master video signal switching device is connected. By transmitting a command from the switching device, control of the slave video signal switching device can be performed by the master video signal switching device.

Further, when a plurality of video signal switching devices are connected, only one master video signal switching device is set, and the other video signal switching devices automatically become slaves.
It becomes possible to control another video signal switching device from the master video signal switching device.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a diagram showing the overall configuration of a video signal switching device according to the present embodiment. This video signal switching device is used for switching the output video of a monitoring video camera. 1 shows a central control unit (CPU) having a microcomputer configuration for controlling the respective circuits of FIG.
Is switched by the changeover switch 2 for switching the video signal. In the figure, 11, 12, 13１２19 are the first.
To ninth video input terminals, and each input terminal 1
Reference numerals 1, 12, 13 and 19 denote terminals to which video signals and the like output by the video camera for monitoring and output are supplied. In this case, up to eight video cameras are connected to the first to eighth input terminals 11 to 18, and another video signal switching device or the like is connected to the ninth input terminal 19. When a plurality of video signal switching devices described later are connected, the ninth input terminal 19 is supplied with a video signal output from another video signal switching device.

A video signal obtained from each video camera or the like at video input terminals 11, 12, 13 # 19 is supplied to a changeover switch 2, and the changeover switch 2 selects the video signal based on the control of the central controller 1. The video signal from the camera (or another video signal switching device or the like) is output.

In this case, in this embodiment, the central controller 1
, The switching is performed within the vertical blanking period of the video signal obtained at each of the input terminals 11 to 19. That is, when it becomes necessary to switch the input video, the central control device 1 waits for the supplied video signal to enter the vertical blanking period, and then outputs the switching signal. The vertical blanking periods of the video signals obtained at the input terminals 11 to 19 are set at the same timing as described later.

The video signal selected by the changeover switch 2 is supplied to an output terminal 4 via a superimpose circuit 3. Then, by connecting a monitor receiver or a VTR to the output terminal 4, it is possible to display an image of a monitoring place on the monitor receiver or to display an image of the monitoring place on the VTR.

In the figure, reference numeral 5 denotes a character generation circuit. The character generation circuit 5 includes a memory (not shown) for storing character data such as characters and symbols, and stores the stored character data in a central control unit. 1 and is supplied to the superimpose circuit 3. Then, the character data supplied to the superimpose circuit 3 is superimposed on the video signal supplied from the changeover switch 2, and the video signal on which this character is superimposed is supplied to the output terminal 4. The character data to be superimposed includes a selected camera number, a number indicating a date and time, a character indicating the setting status of various operation modes, and the like.

In the figure, reference numeral 20 denotes an input selection switch, and reference numeral 30 denotes an active switch. Each of the switches 20, 30 is composed of eight first to eighth switches corresponding to eight video cameras connected to the video input terminals 11 to 18, and a front panel of the video signal switching device. And an operation command of each switch is supplied to the central control device 1. In this case, the respective switches 20 and 30 are connected to the central controller 1
Can be individually turned on under the control of.

The input selection switch 20 is capable of giving an instruction of a video camera (input terminal) selected by the changeover switch 2, and has the above-mentioned lighting function under the control of the central control unit 1, and the video currently being selected. Turn on the switch of the number corresponding to the camera. The active switch 30 can give an instruction of a video camera selected in an automatic switching mode described later, and turns on a switch of a number corresponding to the selected video camera under the control of the central control device 1.

In the figure, reference numeral 6 denotes a setting switch. The setting switch 6 is composed of a plurality of keys and the like, and an operation command of each key is supplied to the central control unit 1. Some are arranged on the front panel together with 30 and others are constituted by dip switches or the like and arranged on the back. In this case, various modes set under the control of the central controller 1 can be set by operating each key. When making this setting, the setting contents can be confirmed by displaying on the screen of the monitor receiver connected to the video signal switching device. That is, when various modes are set, the superimposition circuit 3 superimposes the character data from the character generation circuit 5 on the video signal output from the output terminal 4 so as to display characters and numerals indicating the setting state and the like. Etc. are included.

The central control unit 1 has a memory device 7
Is connected. The memory device 7 comprises a ROM 7a from which only stored data is read out and a rewritable RAM 7b. The ROM 7a is replaceable. The RAM 7b is used as a backup for preventing loss of the stored data. A power supply (not shown) is provided.

Further, a clock device 8 is connected to the central control device 1, and supplies current time data counted by the clock device 8 to the central control device 1 and the memory device 7. In this case, the current time data supplied to the memory device 7 is
The RAM 7b can be stored in accordance with an instruction from the central control device 1.

In the figure, reference numerals 41, 42, 43 and 48 denote first to eighth alarm input terminals, and the alarm input terminals 41 to 48 correspond to the first to eighth video input terminals 11 to 8, respectively.
An alarm signal is supplied from a sensor (infrared sensor or the like) installed at a monitoring location of each video camera, and is obtained at the input terminals 41 to 48. An alarm signal is supplied to the central controller 1. When this alarm signal is supplied to the central controller 1, the video signal from the video camera corresponding to the supplied terminal number is selected and output by the changeover switch 2, and the terminal of the terminal to which the alarm signal is supplied is output. The number and time data are stored in the RAM 7b. Further, an alarm circuit 9 is connected to the central control device 1, and this alarm circuit 9 is composed of a speaker and a warning lamp. When an alarm signal is supplied depending on a set operation mode, a warning sound is output from the speaker. Output and blink the warning lamp. The output of the warning sound and the blinking of the warning lamp are performed for a preset time (10 seconds, 3 seconds).
A mode in which the operation is performed only for 0 seconds, 1 minute, and the like, and a mode in which the operation is continued until the operation of releasing the alarm is performed are prepared.

Further, the central control device 1 of this embodiment has control data bus lines 1a and 1b for communicating control data with other video signal switching devices and computer devices. Communication of control data is performed with the device connected to the connection terminal 1b.

Here, the case where a plurality of video signal switching devices are connected using the bus lines 1a and 1b will be described.
Each video signal switching device is cascaded as shown in FIG. That is, in FIG. 2, 100, 200, 300,
Reference numeral 400 denotes first, second, third, and fourth video signal switching devices. The four video signal switching devices 100 to 400 have the same configuration as that shown in FIG.

By operating a predetermined key (or a switch such as a dip switch) constituting the setting switch 6 of the first video signal switching device 100, the first video signal switching device 100 becomes the master switching device. Set.

The video signal switching devices 100 and 20
The connection terminals of the bus lines 1a of 0,300 are connected to the connection terminals of the bus line 1b of the video signal switching devices 200,300,400. Then, the first to eighth video input terminals 11 to 18 of the respective video signal switching devices 100 to 400
And eight video cameras 101-108, 201-20
8, 301 to 308, 401 to 408, and a total of 3
Connect two video cameras. In this case, each of the video cameras 101 to 408 includes a synchronization signal generator 52.
From the video cameras 101 to 408.
Make the vertical synchronizing signals of the video signals output at the same timing. The synchronization signal generator 52 also includes a power supply circuit, and supplies the power required by each of the video cameras 101 to 408 from the synchronization signal generator 52.

The video signal obtained at the output terminal 4 of the fourth video signal switching device 400 is supplied to the ninth video input terminal 19 of the third video signal switching device 300. Further, similarly, the video signal obtained at the output terminal 4 of the third video signal switching device 300 is connected to the second video signal switching device 2.
00 is supplied to the ninth video input terminal 19 and the video signal obtained at the output terminal 4 of the second video signal switching device 200 is
Ninth video input terminal 1 of first video signal switching device 100
9. Then, the first video signal switching device 100
The video signal obtained at the output terminal 4 of the
To supply. Alternatively, instead of the monitor receiver 51, VT
R (not shown).

Note that the example shown in FIG. 2 shows a state in which the number of video cameras to be connected is maximum (32). Decide the number of cameras.

When a plurality of video signal switching devices 100 to 400 are connected in this way, the first video signal switching device 100 connected to the monitor receiver 51 is connected to the master video signal by operating the setting switch 6 described above. The other video signal switching devices 200 to 400 are connected to the master video signal switching device 10 via the bus lines 1a and 1b.
When a command is transmitted from 0, it automatically operates as a slave video signal switching device. That is, the central controller 1 of each video signal switching device is set to operate as a slave video signal switching device when a command related to switching or the like is transmitted from another device via the bus line 1a or 1b. is there. When the master and the slave are set in this way, the subsequent operations such as switching are performed under the control of the central controller 1 of the video signal switching device 100 of the master. The switching operation corresponding to the command transmitted from the side is performed. When there is a response to the command via the bus lines 1a and 1b, the video signal switching device 100 of the master determines that there is a video signal switching device of the corresponding slave and switches the video signal of the connected slave. Determine the number of devices. Further, when the transmission of the command from the master video signal switching device is stopped, each video signal switching device operates independently.

When the number of the connected slave video signal switching devices is determined, the first to eighth video input terminals 11 to 18 of the master video signal switching device 100 are connected.
Input numbers 1 to 8 are set, and first to eighth video input terminals 11 to 18 of the video signal switching devices 200, 300, and 400 of the respective slaves are set to input numbers 9 to 16, 1 respectively.
Automatically assigned to 7-24, 25-32. And
When the input switching operation is performed, the assigned input number is superimposed by the superimposing circuit 3 of the master video signal switching device 100 and displayed on the monitor receiver 51.

When each video signal switching device is used independently without connecting a plurality of such video signal switching devices, the first to eighth video signal switching devices are controlled by the central control device 1 of each video signal switching device. The video input terminals 11 to 18 are set to input numbers 1 to 8.

Here, the master video signal switching device 1
The communication of control data by bus lines 1a and 1b between 00 and the slave video signal switching devices 200 to 400 will be described. As shown in FIG. Within one vertical cycle (1 V) corresponding to one field period of the video signal supplied from 101 to 408, the master video signal switching device 100
, A period during which a command is transmitted from the second video signal switching device 200 to the second video signal switching device 200, a period b during which a response from the second video signal switching device 200 to the master video signal switching device 100 is performed, A period c in which a command is transmitted from the signal switching device 100 to the third video signal switching device 300, and a period d in which a response from the third video signal switching device 300 to the master video signal switching device 100 is performed. ,
A period e during which a command is transmitted from the master video signal switching device 100 to the fourth video signal switching device 400,
A period f in which a response from the fourth video signal switching device 400 to the master video signal switching device 100 is performed is set. In this manner, communication is performed between the master video signal switching device 100 and each of the slave video signal switching devices 200 to 400, so that the master and all slaves can communicate with each other within one vertical cycle. Will be Accordingly, the transmission of the command from the master video signal switching device 100 to each of the slave video signal switching devices 200 to 400 is completed within one vertical cycle. Then, when there are responses b, d, and f to the transmission of the command in all periods, it is determined that three slaves are connected on the master video signal switching device 100 side. The command transmission or response a to f in each period includes the address data of the transmission destination.

Next, the operation when a plurality of video signal switching devices are connected as shown in FIG. 2 will be described. First, the operation of the setting switch 6 of the master video signal switching device 100 automatically It is assumed that a mode in which switching is performed every second is selected. At this time, the central control device 1 of the master video signal switching device 100
Determine the state of the active switch 30 from 0 to 400,
The video camera activated by each of the active switches 30 is determined.

For example, when all video cameras are set to the active state, the video cameras 101 connected to all the video signal switching devices 100 to 400
408 are sequentially supplied from the output terminal 4 to the monitor receiver 51. That is, first, the switch 2 is switched so that the video signal from the video camera 101 connected to the first video input terminal 11 of the first video signal switching device 100 is output from the output terminal 4. At this time, the input selection switch 20 corresponding to the video camera 101 is turned on. Then, when the output of the video signal from the video camera 101 has elapsed for one second, the second video input terminal 12 of the first video signal switching device 100
Is switched so that the video signal from the video camera 102 connected to is output from the output terminal 4. At this time, the input selection switch 20 corresponding to the video camera 102 is turned on. Thereafter, similarly, the video signals from the video cameras 103, 104 and 108 are switched so as to be output from the output terminal 4 every second, and the input selection switch 20 corresponding to each switching is turned on. In this way, the video signals from the eight video cameras 101 to 108 are switched and output from the output terminal 4 every second, and the video cameras 101 to 108 are output to the monitor receiver 51.
The video from 108 is displayed in order every second.

When one second elapses after the video signal from the video camera 108 is output from the output terminal 4, the ninth video input terminal 19 is selected by the changeover switch 2 of the first video signal switching device 100. At the same time, in response to a command from the central control device 1 of the master (first) video signal switching device 100, the switch 2 of the second video signal switching device 200 is switched to the video signal connected to the first video input terminal 11. Switching is performed so that the video signal from the camera 201 is output from the output terminal 4. At this time, the input selection switch 20 of the second video signal switching device 200 corresponding to the video camera 201 is turned on.

In this manner, the video signal from the video camera 201 is transmitted to the second video signal switching device 20.
0 is supplied to the ninth video input terminal 19 of the first video signal switching device 100 from the output terminal 4 of the first video signal switching device 100, and further from the ninth video input terminal 19 via the changeover switch 2 to the first video signal switching device 100 The video taken by the video camera 201 is displayed on the monitor receiver 51 connected to the output terminal 4 of the monitor 100 and connected to the output terminal 4.

One second after the video signal from the video camera 201 is output from the output terminal 4 of the first video signal switching device 100, the first video signal switching device 100 Switch 2 of the second video signal switching device 200 with the switch 2 of
Is switched so that the video signal from the video camera 202 is output from the output terminal 4. Also at this time, the second video signal switching device 20 corresponding to the video camera 202
The 0 input selection switch 20 is turned on. Then, in the same manner, the video cameras 203 and 204
The video signal from 208 is switched so as to be output from the output terminal 4, and the input selection switch 20 corresponding to each switching is turned on. Thus, the video signals from the eight video cameras 201 to 208 are switched from the output terminal 4 of the second video signal switching device 200 and the output terminal 4 of the first video signal switching device 100 every second. The video cameras 101 to 108 are output to the monitor receiver 51.
Is displayed after the video signal from the
-208 are sequentially displayed every second.

When one second elapses after the video signal is output from the video camera 208, the ninth video input terminal 19 is selected by the changeover switch 2 of the first video signal switching device 100. In response to a command from the central control unit 1 of the master (first) video signal switching device 100, the ninth video input terminal 19 is selected by the changeover switch 2 of the second video signal switching device 200, and the third video signal is further selected. The video signal from the video camera 301 connected to the first video input terminal 11 is switched from the output terminal 4 by the changeover switch 2 of the signal switching device 300. At this time, the input selection switch 20 of the third video signal switching device 300 corresponding to the video camera 301 is turned on.

In this manner, the video signal from the video camera 301 is transmitted to the third video signal switching device 30.
0 is supplied to the ninth video input terminal 19 of the second video signal switching device 200 from the output terminal 4 of the second video signal switching device 200. Of the first video signal switching device 100, from the output terminal 4 to the ninth video input terminal 19 of the first video signal switching device 100. Video signal switching device 100
The video captured by the video camera 301 is displayed on the monitor receiver 51 connected to the output terminal 4.

When one second elapses after the video signal from the video camera 301 is output from the output terminal 4 of the first video signal switching device 100, the first and second video signals are transmitted. While the changeover switch 2 of the changeover devices 100 and 200 remains unchanged, the third video signal changeover device 30
The changeover switch 2 of 0 is switched so that the video signal from the video camera 302 is output from the output terminal 4.
Also at this time, the input selection switch 20 of the third video signal switching device 300 corresponding to the video camera 302 is turned on. Then, similarly, the video signals from the video cameras 303, 304, and 308 are switched so as to be output from the output terminal 4 every second, and the input selection switch 20 corresponding to each switching is turned on. . In this manner, the video signals from the eight video cameras 301 to 308 are switched and output from the output terminal 4 of the first video signal switching device 100 every second, and the video cameras 101 to After the video signals from 108, 201 to 208 are displayed, video cameras 301 to 308
Are sequentially displayed every second.

When one second has elapsed since the video signal was output from the video camera 308, the ninth video input terminal 19 was selected by the changeover switch 2 of the first video signal switching device 100. According to a command from the central controller 1 of the master (first) video signal switching device 100, the ninth video input terminal 19 is selected by the changeover switch 2 of the second and third video signal switching devices 200 and 300,
Further, the changeover switch 2 of the fourth video signal changeover device 400
The video camera 4 connected to the first video input terminal 11
The image signal is switched so as to output the video signal from the output terminal 4 from the output terminal 4. At this time, the input selection switch 20 of the fourth video signal switching device 400 corresponding to the video camera 401 is turned on.

In this manner, the video signal from the video camera 401 is transmitted to the fourth video signal switching device 40.
0 from the output terminal 4 to the ninth video input terminal 19 of the third video signal switching device 300, and from the ninth video input terminal 19 via the changeover switch 2 to the third video signal switching device 300 Of the second video signal switching device 200, from the output terminal 4 to the ninth video input terminal 19 of the second video signal switching device 200, and from the ninth video input terminal 19 to the second Video signal switching device 200
Of the first video signal switching device 100, and from the ninth video input terminal 19 to the switch 2
Is supplied to the output terminal 4 of the first video signal switching device 100 via the monitor terminal 5 connected to the output terminal 4
1, an image captured by the video camera 201 is displayed.

When one second elapses after the video signal from the video camera 401 is output from the output terminal 4 of the first video signal switching device 100, the first, second, and third video signals are output. The changeover switch 2 of the fourth video signal switching device 400 is changed to the video camera 4 without changing the changeover switch 2 of the video signal switching devices 100, 200 and 300 of FIG.
The video signal is switched from the output terminal 4 to output the video signal from the output terminal 02. Also at this time, the input selection switch 20 of the third video signal switching device 400 corresponding to the video camera 402 is turned on. In the same manner, the video signals from the video cameras 403, 404, and 408 are switched so as to be output from the output terminal 4 every second.
The input selection switch 20 corresponding to each switching is turned on. In this manner, eight video cameras 4 are output from the output terminal 4 of the first video signal switching device 400 every second.
01 to 408 are switched and output, and the video cameras 101 to 108 and 201 are supplied to the monitor receiver 51.
After the video signals from 208 and 301 to 308 are displayed, the video from the video cameras 401 to 408 is sequentially displayed every second.

When one second has elapsed since the video signal was output from the video camera 408, the video signal from the video camera 101 connected to the first video input terminal 11 of the first video signal switching device 100 is then output. Output video signal to output terminal 4
The switch 2 is changed over so that the video signal is output from the video camera 101, and thereafter the video camera 101, 102 # is repeatedly switched in the above-described order.

In this way, each of the video cameras 101 to
108, 201 to 208, 301 to 308, 401 to 4
08, the video signal to be photographed and output is sequentially supplied to the monitor receiver 51 every one second.
Is displayed every second, and all video signal switching devices 100 to 40
When eight video cameras are connected to 0 at a time, images from a total of 32 video cameras are displayed at intervals of 32 seconds, one second at a time.

Therefore, it is possible to monitor up to 32 locations with only one monitor receiver 51 (or VTR), and it is possible to monitor many locations satisfactorily with a monitoring system using a small number of devices. Further, since the control of the plurality of video switching devices 100 to 400 is performed by the central control device 1 of the master video signal switching device 100, a computer device for controlling the plurality of video signal switching devices in an integrated manner is not required. This also simplifies the configuration of the monitoring system.

When monitoring is performed by this switching device, the input selection switch 2 of each video signal switching device is used.
The lighting state of 0 indicates which video camera (input terminal) is displaying an image. In addition, the monitor receiver 5
This input number is also displayed at the corner of the image displayed by 1 by superimposing the character data of the input number in the superimpose circuit 3, and this number display also indicates which video camera is displaying the image. Will be announced. Therefore,
For example, when the video switched by the video switching devices 100 to 400 is recorded on a VTR, each monitoring location hardly changes in the same room, and when the video alone cannot determine which location, this number display is used. It is possible to determine where the recorded video is.

In this case, the input number is displayed by the central control unit 1 of the master video signal switching device 100 by judging the number of connected slaves and by the second, third, and fourth video signal switching devices. While switching the video from 200, 300, and 400, the input number is automatically changed. That is, the first to eighth video input terminals 11 to 18 of the four video signal switching devices 100 to 400 are connected to input numbers 1 to 8, 9 to 16, 17 to 2
4, 25 to 32, for example, when the video signal obtained at the first video input terminal 11 of the second video signal switching device 200 is selected and displayed on the monitor receiver 51, the input number 9 is displayed. Therefore, in the video signal switching devices 200 to 400 of the respective slaves, there is no need to perform the operation of changing the setting of the input number.

In the automatic switching mode, for example, when any one of the input selection switches 20 is pressed, the video input terminal of the input number corresponding to the pressed input selection switch 20 is connected. Switch to the obtained image. Then, when the same input selection switch 20 is pressed again, the mode is returned to the automatic switching mode in which the switching is performed every predetermined time. Therefore, when monitoring by automatic switching is performed, it is possible to temporarily monitor a specific monitoring location temporarily.

When there is a place where there is no need to perform monitoring, the active switch 30 corresponding to the video camera installed in a place where there is no need to perform monitoring is set to an inactive state, so that the video camera can be switched off. No video is displayed, which is suitable, for example, when it is desired to change the monitoring place depending on time.

When an alarm signal is supplied to any of the alarm input terminals 41 to 48 of any of the video signal switching devices during the automatic switching mode, the automatic switching is temporarily stopped and the alarm signal is stopped. The video signal from the video camera corresponding to the number of the terminal to which the alarm signal is supplied is selected by the changeover switch 2 and output, and the number and time data of the terminal to which the alarm signal is supplied are stored in the RAM 7b.
Further, depending on the set operation mode, a warning sound is output from the speaker for a predetermined time and a warning lamp blinks for a predetermined time. Therefore, for example, by disposing an infrared sensor at each monitoring location and supplying an alarm signal from this infrared sensor to the alarm input terminals 41 to 48 of each video signal switching device, there is no intruder at each monitoring location. Automatically displays an image of the surveillance place where the intruder was located on the monitor receiver 51, and a warning is given by the alarm circuit 9, for example, when an image of another surveillance place is displayed. Even if there is an intruder, it is possible to reliably monitor the intruder without overlooking it. Also, instead of monitoring in real time with the monitor receiver 51, a VTR
In the case of monitoring a place where people are unmanned at night, the presence of this intruder is later known from the data stored in the memory device 7.

When the automatic switching mode is released, a manual switching operation in accordance with the operation of the input selection switch 20 is performed.

As described above, according to the video signal switching device of the present embodiment, when a plurality of video signal switching devices are connected, the switching operation is automatically and integrally performed. Therefore, although one video signal switching device can connect only eight video cameras, for example, by connecting four video signal switching devices, 32 video cameras can be connected, and the video from each video camera can be connected. Can be monitored. in this case,
Just by setting one predetermined video signal switching device as a master, the other video signal switching devices automatically become slaves,
Various operations such as switching are performed by a command from the central control device 1 of the master video signal switching device,
No setting work is required on the slave side. Further, transmission of a command from the video signal switching device of the master and transmission of a response to the command include, as shown in FIG.
This is performed for all video signals handled by this video signal switching device within one vertical cycle, so that input video switching or the like is not instructed over two vertical cycles, and the video is disturbed at the time of switching. Nothing. That is, in each video signal switching device, when an input video switching instruction is issued, switching is performed in the next vertical blanking period. Therefore, switching is performed within the same vertical blanking period in all connected video signal switching devices. Are performed, the switching timings match, and the video is not disturbed at the time of switching.

In the above embodiment, a video camera for monitoring is connected to all the video input terminals 11 to 19, but another video signal source may be connected to this video input terminal. In addition, the present invention is not limited to the above-described embodiment, but may take various other configurations.

[0055]

According to the present invention, when a plurality of video signal switching devices are connected, the switching operation is performed automatically and integrally, so that a very large number of locations can be monitored simultaneously with a video camera. . In this case, by simply setting one predetermined video signal switching device as a master, the other video signal switching devices automatically become slaves, and setting work for connection can be easily performed. When a plurality of video signal switching devices are connected in this way, transmission of a command from the master video signal switching device and transmission of a response to the command are performed within one vertical cycle of the video signal. The input video switching is not performed over two vertical cycles, and the switching is performed within the same vertical blanking period by all the connected video signal switching devices, and the switching timings match. The video is not disturbed at the time of switching, and can be used in exactly the same manner as when only one video signal switching device is used.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a video signal switching device of the present invention.

FIG. 2 is a connection diagram illustrating a use state of the video signal switching device according to the embodiment;

FIG. 3 is a timing chart for explaining an embodiment of a video signal switching device according to the present invention;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Central control device 2 Changeover switch 3 Superimpose circuit 4 Output terminal 5 Character generation circuit 6 Setting switch 7 Memory device 7a ROM 7b RAM 8 Clock device 9 Alarm circuit 11-19 Video input terminal 20 Input selection switch 30 Active switch 41- 48 Alarm input terminal 51 Monitor receiver 52 Synchronization generator 100, 200, 300, 400 Video signal switching device 101-108, 201-208, 301-308, 4
01-408 Video camera

Claims (2)

(57) [Claims] 1. A video signal switching device for switching and outputting video signals supplied from a plurality of video signal sources, wherein when a plurality of said video signal switching devices are connected, a predetermined one
In one vertical cycle of the video signal supplied from the video signal source, the master video signal switching device and all of the master video signal switching devices are used as masters and the other video signal switching devices are slaves. A video signal switching device that performs bidirectional communication with a slave video signal switching device. 2. A video signal switching device for switching and outputting video signals supplied from a plurality of video signal sources, wherein a master video signal switching device is operated by operating a predetermined setting means.
And receives commands from other connected video signal switching devices.
A video signal switching device that automatically operates as a slave video signal switching device when a video signal is input.