JPH04234289A - Video signal switching device - Google Patents

Abstract

PURPOSE:To easily and satisfactorily connect plural video signal switching devices. CONSTITUTION:When the plural video signal switching devices are connected, a prescribed one video signal switching device 100 is operated as a master, and another video signal switching devices 200, 300, and 400 as slaves, and also, continuous serial numbers are attached on the video input terminals of all the video signal switching devices 100-400 at a master side, and prescribed switching processing is performed based on attached continuous serial numbers.

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 application to a switching device for a surveillance video camera.

0002

[Prior Art] Conventionally, when video cameras for surveillance are installed at multiple locations, it is conceivable to provide as many monitor receivers as there are video cameras, and have each monitor receiver receive the image of each monitoring location. As the number of places to be monitored increases, the number of monitor receivers as well as video cameras increases, resulting in the inconvenience that the configuration of the monitoring system becomes complicated. In addition, when recording video signals captured by a surveillance video camera on a video tape recorder (VTR) instead of a monitor receiver, similarly, as the number of places to be monitored increases, the number of VTRs increases. This has the disadvantage of complicating the configuration of the monitoring system.

For this reason, a video signal switching device for surveillance cameras has been put into practical use that switches video signals supplied from surveillance video cameras installed at multiple locations and selectively supplies them to one monitor receiver. .

[0004] This video signal switching device for surveillance cameras is one in which video signals supplied from, for example, a plurality of connected surveillance video cameras are sequentially switched at predetermined intervals and supplied to a single monitor receiver. It is. By using this video signal switching device, supervisors can monitor all locations simply by viewing the video displayed on one monitor receiver, making it easy to configure the surveillance system. At the same time, the supervisor can easily perform monitoring. Furthermore, even when a video signal obtained by a surveillance video camera is recorded on a VTR, by using this video signal switching device, the video signal can be efficiently recorded on a single VTR.

[0005]

[Problems to be Solved by the Invention] However, with this type of video signal switching device for surveillance cameras, there is a limit to the number of video cameras that can be connected with one switching device.For example, one switching device can connect eight video cameras. However, if more than eight video cameras are to be used for monitoring, 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 monitor receivers or VTRs required increases accordingly, resulting in an inconvenience that the system configuration becomes complicated. For this reason, multiple switching devices must be operated in conjunction to switch between one monitor receiver or VTR.
However, in order to operate multiple switching devices in conjunction with each other, it is necessary to control them with a computer device such as a personal computer. for,
It is necessary to create a program for controlling the switching in advance and set it in the computer device, which is inconvenient and requires time and cost.

An object of the present invention is to enable a plurality of video signal switching devices to be linked together with a simple configuration.

[0007]

[Means for Solving the Problems] The present invention provides a video signal switching device (100, 200, 300, 400) are connected, one predetermined video signal switching device (10
0) as the master, and the other video signal switching devices (200, 3
00, 400) as a slave, and on the master video signal switching device (100) side, connect continuously to the input terminals (11 to 19) of all connected video signal switching devices (100, 200, 300, 400). A series of numbers are assigned to each switch, and a predetermined switching process is performed based on the assigned series of consecutive numbers.

[0008]

[Operation] By doing this, when multiple video signal switching devices are connected, a series of consecutive numbers are automatically assigned to each video signal input terminal under the control of the master video signal switching device. By using this continuous series of numbers, integrated control of a plurality of video signal switching devices can be performed satisfactorily.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An 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 the video signal switching device of this example. This video signal switching device is used for switching the output video of a surveillance video camera, and 1 in the figure is the video signal switching device. A central control unit (CPU) having a microcomputer configuration that controls each circuit of the central control unit 1 is shown.
Under the control of , the changeover switch 2 for video signal changeover is performed. In addition, 11, 12, 13...19 in the figure are the first
- Indicates a ninth video input terminal, and each input terminal 11
, 12, 13...19 are terminals to which video signals captured and output by a surveillance video camera are supplied.In the initial setting state, the first to eighth video input terminals 11 to 18 are connected to the camera. Input number names of cameras 1 to 8 are given. In this case, a maximum of eight video cameras are connected to the first to eighth input terminals 11 to 18, and other video signal switching devices and the like are connected to the ninth input terminal 19. In addition, when connecting a plurality of video signal switching devices to be described later, the video signals output from the other video signal switching devices are supplied to this ninth input terminal 19.

[0011] Then, video signals obtained from each video camera or the like to the video input terminals 11, 12, 13, . The video signal from the camera (or other video signal switching device, etc.) is output.

In this case, in this example, the central control device 1
When the switching is performed under the control of the input terminals 11 to 19, the switching is performed within the vertical blanking period of the video signals obtained at the input terminals 11 to 19. That is, when it becomes necessary to switch the input video, the central control device 1 waits until the supplied video signal enters the vertical blanking period, and then outputs the switching signal. Note that the vertical blanking periods of the video signals obtained at each of the input terminals 11 to 19 are aligned with the same timing, as will be described later.

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

Reference numeral 5 in the figure indicates a character generation circuit, and this character generation circuit 5 is equipped with a memory (not shown) for storing character data such as characters and symbols, and the stored character data is transmitted to a central control unit. 1 and supplies it 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 with this character superimposed is output to the output terminal 4.
supply to. The superimposed character data includes numbers indicating the selected camera number, date and time, characters indicating the setting status of various operation modes, and the like.

FIG. 6 is a diagram showing a state in which the camera number and date and time are superimposed on the output video. As shown in the figure, for example, when the video signal obtained from the first video input terminal 11 is output, At the bottom right of the screen, there is a display that shows the input (camera) number [CAMERA1], a display that shows the current time in [hours: minutes: seconds], and a display that shows the date in [year: month: day]. and these characters are displayed on the screen of the monitor receiver.

[0016]The display positions of these characters are as follows:
This can be changed by performing a predetermined operation as a display location selection mode by operating a setting switch 6, which will be described later. That is, as the display location selection mode, after displaying [DISPLAY LOCATION] (display location) on the screen as shown in FIG. You can change the display position of each character from the bottom right of the screen, top right, top left, bottom left, bottom right, etc. each time the character is displayed, and when the desired display position is reached, you can change the display position from the display location selection mode to normal. By returning to the mode, characters indicating the camera number, date and time, etc. will be displayed at the selected position. Note that FIG. 7 is an example in which the screen is displayed at the upper left.

Furthermore, the display of the camera number can be changed to characters such as alphabets by operating a setting switch 6, which will be described later, to set the camera ID setting mode. That is, by setting the camera ID setting mode, a list of displayable characters such as numbers, alphabets, symbols, etc. is displayed as shown in FIG. By sequentially selecting the required characters, you can set a display character to replace the camera number. In the case of FIG. 8, a state is shown in which [ENTRANCE], which is an entrance, is set instead of [CAMERA2], which indicates camera number 2. This set camera ID is stored in the RAM 7b of the memory device 7, which will be described later.

When this camera ID setting mode is performed, the set character is displayed in place of the camera number when switching to the set camera number is performed thereafter. For example, for camera number 2 mentioned above, [ENTRAN
CE], when the video input terminal 12 is selected, [ENTRANCE] is displayed superimposed on the output video as shown in FIG.

Further, in FIG. 1, 20 indicates an input selection switch, and 30 indicates an active switch. These respective switches 20 and 30 are connected to the video input terminals 11 to 18.
It consists of eight switches, numbered 1 to 8, corresponding to the eight video cameras connected to the central control unit 1, which are arranged on the front panel of this video signal switching device, and the operation commands for each switch are sent to the central control unit 1. It is designed to be supplied to In this case, each of the switches 20 and 30 can be individually turned on under the control of the central control device 1.

The input selection switch 20 can specify the video camera (input terminal) selected by the changeover switch 2, and can also specify the currently selected video by the above-mentioned lighting function under the control of the central control device 1. Turn on the switch number corresponding to the camera. Further, the active switch 30 is capable of instructing a video camera to be selected in an automatic switching mode to be described later, and lights up a switch numbered corresponding to the selected video camera under the control of the central controller 1.

Further, reference numeral 6 in the figure indicates a setting switch, and this setting switch 6 is composed of a plurality of keys, etc., and the operation command of each key is supplied to the central control unit 1. There are some that are arranged on the front panel together with 30, and others that are composed of dip switches and the like and are arranged on the back. In this case, various modes controlled by the central controller 1 can be set by operating each key. For example, the above-mentioned display location selection and camera ID setting can be performed. When making these settings, the settings can be confirmed by displaying them on the screen of a monitor receiver connected to the video signal switching device. That is, when setting various modes, etc., the character data from the character generation circuit 5 is superimposed in the superimpose circuit 3, so that characters and numbers indicating the setting state etc. are added to the video signal output from the output terminal 4. Contains information such as.

The central control unit 1 also includes a memory device 7.
is connected. This memory device 7 is composed of a ROM 7a from which only pre-stored data is read, and a RAM 7b from which the stored data can be rewritten.The ROM 7a is replaceable, and the RAM 7b is used as a backup to prevent loss of stored data. A power source (not shown) is provided.

Furthermore, a clock device 8 is connected to the central control device 1, and current time data counted by the clock device 8 is supplied to the central control device 1 and the memory device 7. For example, when superimposing time on the output video signal, the superimposed character (
number). Further, the current time data supplied to the memory device 7 is stored in the RAM according to instructions from the central control device 1.
7b can be memorized.

In the figure, 41, 42, 43...48 indicate first to eighth alarm input terminals, and these alarm input terminals 41 to 48 are connected to the first to eighth video input terminals 11 to 48.
It is compatible with 8 video cameras connected to 18, and an alarm signal is supplied from a sensor (infrared sensor, etc.) installed at the monitoring location of each video camera.
Alarm signals obtained at the input terminals 41 to 48 are supplied to the central control device 1. When this alarm signal is supplied to the central control device 1, the changeover switch 2 selects and outputs the video signal from the video camera corresponding to the number of the supplied terminal, and also outputs the video signal from the video camera corresponding to the terminal number supplied with the alarm signal. 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, and depending on the set operation mode, when an alarm signal is supplied, a warning sound is emitted from the speaker. The output is output and the warning lamp flashes. A mode in which the warning sound is output and the warning lamp flashes for a preset time (10 seconds, 30 seconds, 1 minute, etc.) and a mode in which it continues until the alarm is canceled are provided.

Furthermore, 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. Control data is communicated with the device connected to the connection terminal 1b.

Now, to explain the case where a plurality of video signal switching devices are connected using these bus lines 1a and 1b, using these bus lines 1a and 1b,
The respective video signal switching devices are connected in cascade as shown in FIG. That is, in FIG. 2, 100, 200, 300,
Reference numeral 400 indicates first, second, third, and fourth video signal switching devices, and these four video signal switching devices 100 to 400 have the configuration shown in FIG. 1 and are the same.

Then, 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 is set as the master switching device. Set.

[0028] Then, the video signal switching devices 100, 200
, 300 are connected to the connection terminals of the bus lines 1b of the video signal switching devices 200, 300, and 400. And each video signal switching device 1
Eight video cameras 101-108, 201-208 are connected to the first to eighth video input terminals 11-18 of 00-400.
, 301-308, 401-408, total 32
Connect a video camera. In this case, each of the video cameras 101 to 408 is supplied with a synchronization signal from the synchronization signal generator 52, and this synchronization signal causes the video cameras 101 to 408 to capture images at the same timing. Make the synchronization signals have the same timing. Note that this synchronizing signal generator 52 also includes a power supply circuit, and the synchronizing signal generator 52 also supplies the power required by each of the video cameras 101 to 408.

The video signal obtained at the output terminal 4 of the fourth video signal switching device 400 is then supplied to the ninth video input terminal 19 of the third video signal switching device 300. Furthermore, in the same manner, the video signal obtained at the output terminal 4 of the third video signal switching device 300 is transferred to the second video signal switching device 2.
The video signal supplied to the ninth video input terminal 19 of 00 and 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
Supply to 9. Then, the first video signal switching device 100
The video signal obtained at the output terminal 4 of the monitor receiver 51
supply to. Alternatively, instead of the monitor receiver 51, a VT
Connect R (not shown).

Note that the example shown in FIG. 2 shows the maximum number of video cameras connected (32 cameras); in reality, the number of video cameras connected is 32 or less depending on the monitoring location, etc. Decide on the number of cameras.

When a plurality of video signal switching devices 100 to 400 are connected in this manner, by operating the setting switch 6 described above, the first video signal switching device 100 connected to the monitor receiver 51 is switched to the master video signal. 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 sent from 0, it automatically operates as a slave video signal switching device. That is, the central control device 1 of each video signal switching device is set to operate as a slave video signal switching device when a command related to switching, etc. is transmitted from another device via the bus line 1a or 1b. be. Once the master and slave are set in this way, subsequent operations such as switching are performed under the control of the central control device 1 of the master video signal switching device 100, and the slave side central control device 1 Performs switching operations, etc. in response to commands transmitted from the side. Note that when there is a response to the command via the bus lines 1a and 1b, the master video signal switching device 100 side determines that there is a corresponding slave video signal switching device, and switches the video signal of the connected slave. Determine the number of devices. Furthermore, when the master video signal switching device no longer sends commands, each video signal switching device begins to operate independently.

After determining the number of connected slave video signal switching devices, the first to eighth video input terminals 11 to 18 of the master video signal switching device 100 are
In addition to setting camera numbers (input numbers) 1 to 8, the first to eighth video input terminals 11 to 18 of the video signal switching devices 200, 300, and 400 of each slave are set to camera numbers 9 to 16, and 17 to 8, respectively. 24, 25-32 automatically. Then, when an input switching operation is performed, this assigned camera number is transferred to the master video signal switching device 1.
The image is superimposed by the superimpose circuit 3 of No. 00 and displayed on the monitor receiver 51. However, camera I
If D is the set camera number, the set camera ID is superimposed and displayed instead of the camera number.

Note that when each video signal switching device is used alone without connecting a plurality of devices, the central control device 1 of each video signal switching device controls each of the first to eighth video signal switching devices. Video input terminals 11 to 18 are automatically set to camera numbers (input numbers) 1 to 8.

That is, when a plurality of video signal switching devices 100, 200, etc. are connected as shown in FIG. 2, for example, when the first video input terminal 11 of the second video signal switching device 200 is selected, When displaying camera number 9 with superimposition and using only this second video signal switching device 200, the same first video input terminal 1
When you select 1, superimpose camera number 1.
Display.

Here, this master video signal switching device 1
00 and the slave video signal switching devices 200 to 400 via the bus lines 1a and 1b. Communication between the video signal switching devices is as shown in FIG. Master video signal switching device 100 within one vertical period (1V) corresponding to one field period of the video signals supplied from 101 to 408.
A period a in which a command is transmitted from the second video signal switching device 200 to the second video signal switching device 200, a period b in which a response is sent from the second video signal switching device 200 to the master video signal switching device 100, and a period b in which a command is transmitted from the second video signal switching device 200 to the master video signal switching device 100. A period c during which a command is transmitted from the signal switching device 100 to the third video signal switching device 300, and a period d during which a response is sent from the third video signal switching device 300 to the master video signal switching device 100. ,
a period e during which commands are transmitted from the master video signal switching device 100 to the fourth video signal switching device 400;
A period f is set during which a response is made from the fourth video signal switching device 400 to the master video signal switching device 100. By communicating in this way between the master video signal switching device 100 and each of the slave video signal switching devices 200 to 400, mutual communication is performed between the master and all slaves within one vertical period. be exposed. Therefore, the transmission of commands from the master video signal switching device 100 to each slave video signal switching device 200 to 400 is completed within one vertical period. If there are responses b, d, and f to the command transmission in all periods as described above, it is determined that three slaves are connected on the master video signal switching device 100 side. Note that the command transmissions or responses a to f in each period include address data of the destination.

Here, the transmission format of this command is shown in FIG. 4. Each command a, c, e consists of 4 bytes, and the first byte indicates the destination address (one of the three slaves). is shown, the next 2 bytes show data related to the command, and the last 1 byte contains a correction code EC.
C is added. Also, when the transmission format of the response to this command is shown in Figure 5, each response b, d, f is 3
Consists of bytes, the first byte indicates the destination address (master video signal switching device), the next byte indicates data related to the response, and the last byte adds a correction code ECC. .

Next, to explain the operation when a plurality of video signal switching devices are connected as shown in FIG. 2, first, by operating the setting switch 6 of the master video signal switching device 100, the Assume that you have selected a mode in which switching occurs every second. At this time, the central control device 1 of the master video signal switching device 100 controls each video signal switching device 10.
Determine the state of the active switch 30 from 0 to 400,
The video camera that is activated by each active switch 30 is determined.

For example, when all the video cameras are set to the active state, the video cameras 101 connected to all the video signal switching devices 100 to 400
It controls so that the images from 408 to 408 are sequentially supplied to the monitor receiver 51 from the output terminal 4. That is, first, the changeover 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 outputted from the output terminal 4. At this time, the input selection switch 20 corresponding to the video camera 101 is turned on, and camera number 1 is superimposed on the output video. When the video signal from the video camera 101 is output for one second, the video signal from the video camera 102 connected to the second video input terminal 12 of the first video signal switching device 100 is transferred to the output terminal 4. Switch to output from. At this time, the input selection switch 20 corresponding to the video camera 102 is turned on, and camera number 1 is superimposed on the output video. Thereafter, the video signals from the video cameras 103, 104, .
lights up. At this time as well, the camera number corresponding to the input selection is superimposed on the output video. 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 signals from the eight video cameras 101 to 108 are output to the monitor receiver 51 every second. are displayed in order.

When one second has elapsed since the video signal from the video camera 108 was output from the output terminal 4, the ninth video input terminal 19 is selected using 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 changeover switch 2 of the second video signal switching device 200 is switched to the video signal connected to the first video input terminal 11. The video signal from the camera 201 is switched to be 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, and camera number 9 is superimposed on the output video.

Here, the state changes from the state in which camera number 8 of the first (master) video signal switching device 100 is selected to the state in which camera number 9 of the second (slave) video signal switching device 200 is selected. To explain the changes in 1 with reference to the flowchart in FIG. 10, during this automatic switching, it is determined whether a preset predetermined time (i.e. 1 second) has elapsed since camera number 8 was selected, and 1 When seconds have passed, the central control device 1 of the master video signal switching device 100
Under this control, the changeover switch 2 of the first video signal switching device 100 selects the ninth video input terminal 19, and the signal is transmitted from the central control device 1 of the master video signal switching device 100 via the bus lines 1a, 1b. to the second video signal switching device 200, and the changeover switch 2 connects the first video input terminal 11 to the second video signal switching device 200.
Send a command to select. When this command is transmitted, the specified switching is performed within the next vertical blanking period under the control of the central control device 1 in the second video signal switching device 200. Also, this command will cause the second
The corresponding input selection switch 20 of the video signal switching device 200 is turned on. And when this switching is done,
Under the control of the central control device 1 of the master video signal switching device 100, the superimpose circuit 3 superimposes a character indicating camera number 9 on the output video signal, and the camera number 9 is added to the video displayed on the monitor receiver 51. Display the character shown.

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

Then, 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 With the changeover switch 2 of the second video signal switching device 200 unchanged, changeover switch 2 of the second video signal switching device 200
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
0 input selection switch 20 is turned on. Then, in the same manner, the video cameras 203, 204...
The video signal from 208 is switched to be output from the output terminal 4, and the corresponding input selection switch 20 is lit for each switch. In this way, the video signals from the eight video cameras 201 to 208 are switched every second 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. The video cameras 101 to 108 are output to the monitor receiver 51.
After the video signal from the video camera 201 is displayed,
The images from ~208 are displayed in order every second.

When one second has elapsed since the video signal from the video camera 208 was output, the switch 2 of the first video signal switching device 100 is selected to select the ninth video input terminal 19. In response to a command from the central control device 1 of the master (first) video signal switching device 100, the changeover switch 2 of the second video signal switching device 200 selects the ninth video input terminal 19, and then the third video signal switching device 200 selects the ninth video input terminal 19. The changeover switch 2 of the signal switching device 300 is used to switch the video signal from the video camera 301 connected to the first video input terminal 11 so that it is output from the output terminal 4. 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.

By doing this, the video signal from this video camera 301 is transferred to the third video signal switching device 30.
0 from the output terminal 4 of the second video signal switching device 200 to the ninth video input terminal 19 of the second video signal switching device 200, and from the ninth video input terminal 19 via the changeover switch 2 to the second video signal switching device 200. from this output terminal 4 to the ninth video input terminal 19 of the first video signal switching device 100, and from this ninth video input terminal 19 via the changeover switch 2. video signal switching device 100
The image taken by the video camera 301 is displayed on a monitor receiver 51 connected to the output terminal 4 of the video camera 301 .

[0045] Then, one second 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 With the changeover switches 2 of the changeover devices 100 and 200 unchanged, the third video signal changeover device 30
0 changeover switch 2 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, in the same manner, the video signals from the video cameras 303, 304, . . In this way, 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 signals from the eight video cameras 301 to 308 are switched and outputted to the monitor receiver 51. After the video signals from 108, 201 to 208 are displayed, the video cameras 301 to 308
Videos from the video are displayed in sequence every second.

When one second has elapsed since the video signal from the video camera 308 was output, the switch 2 of the first video signal switching device 100 is selected to select the ninth video input terminal 19. In response to a command from the central control device 1 of the master (first) video signal switching device 100, the changeover switch 2 of the second and third video signal switching devices 200, 300 selects the ninth video input terminal 19,
Furthermore, the changeover switch 2 of the fourth video signal switching device 400
A video camera 4 connected to the first video input terminal 11 at
The video signal from 01 is switched to be output from 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.

By doing this, the video signal from this video camera 401 is transferred to the fourth video signal switching device 40.
0 output terminal 4 to the ninth video input terminal 19 of the third video signal switching device 300, and from this ninth video input terminal 19 via the changeover switch 2, the signal is supplied to the third video signal switching device 300. from this output terminal 4 to the ninth video input terminal 19 of the second video signal switching device 200, and from this ninth video input terminal 19 via the changeover switch 2. video signal switching device 200
from this output terminal 4 to the ninth video input terminal 19 of the first video signal switching device 100, and from this ninth video input terminal 19 to the changeover switch 2.
is supplied to the output terminal 4 of the first video signal switching device 100 via the monitor receiver 5 connected to this output terminal 4.
1, a video shot by the video camera 201 is displayed.

[0048] Then, one second 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 video signal from the first, second and third video signal switching device 100 is output. While the changeover switches 2 of the video signal switching devices 100, 200, and 300 are left as they are, the changeover switch 2 of the fourth video signal switching device 400 is changed to the video camera 4
The video signal from 02 is switched to be output from the output terminal 4. 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. Then, in the same manner, the video signals from the video cameras 403, 404, . . In this way, the first video signal switching device 4
8 video cameras 40 every second from output terminal 4 of 00
The video signals from 1 to 408 are switched and output, and the video signals from the video cameras 101 to 108, 201 to
After the video signals from the video cameras 208, 301-308 are displayed, the videos from the video cameras 401-408 are sequentially displayed every second.

When one second has elapsed since the video signal from the video camera 408 was output, the next video signal is output from the video camera 101 connected to the first video input terminal 11 of the first video signal switching device 100. Output the video signal to output terminal 4.
The changeover switch 2 is changed so that the output is output from the video cameras 101, 102, and so on, and the changeover is repeated in the above-mentioned order.

[0050] In this way, each video camera 101~
108,201~208,301~308,401~4
The video signal shot and output from 08 is sequentially supplied to the monitor receiver 51 every second, and the monitor receiver 51
Displayed in seconds, all video signal switching devices 100 to 40
If 8 video cameras are connected to 0, images from a total of 32 video cameras will be displayed for 1 second at a cycle of 32 seconds.

[0051] Therefore, up to 32 locations can be monitored with just one monitor receiver 51 (or VTR), and a large number of locations can be monitored satisfactorily with a monitoring system using a small number of devices. Further, 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.
Therefore, there is no need for a computer device that centrally controls a plurality of video signal switching devices, and from this point of view as well, the configuration of the monitoring system is simplified.

When monitoring is performed by this switching device, the input selection switch 2 of each video signal switching device is
The lighting state of 0 indicates which video camera (input terminal) the video is being displayed from. In addition, the monitor receiver 5
This camera number (input number) is also displayed in the corner of the video displayed in 1 by superimposing the character data of the camera number in the superimpose circuit 3, and this number display also indicates which video camera the video is from. You will be notified if it is being displayed. Therefore, for example, these video switching devices 100 to 40
When the video switched with 0 is recorded on a VTR, and each monitoring location is in the same room with almost no changes and the location cannot be determined from the video alone, this number display will tell you where the recorded video is. You can determine if there is.

In this case, the master video signal switching device 10
The central control device 1 of No. 0 determines the number of connected slaves and switches the second, third, and fourth video signal switching devices 200, 3.
While switching between images from 00 and 400, the display of the camera number (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 camera numbers 1 to 8, 9 to 16, 17 to
For example, when a video signal obtained from the first video input terminal 11 of the second video signal switching device 200 is selected and displayed on the monitor receiver 51, the camera number Display 9. Therefore, in each slave video signal switching device 200 to 400, there is no need to change the camera number setting.

When in this automatic switching mode, for example, if any input selection switch 20 is pressed, the video input terminal of the camera number corresponding to the pressed input selection switch 20 is selected. Switch to the available image. When the same input selection switch 20 is pressed again, the mode is returned to the automatic switching mode in which switching is performed at predetermined time intervals. Therefore, when performing monitoring by automatic switching, it is possible to temporarily focus on monitoring a specific monitoring location.

Furthermore, when there is a place that does not need to be monitored, the active switch 30 corresponding to the video camera installed in the place that does not need to be monitored is set to the inactive state, thereby preventing the video camera from monitoring the place. No video is displayed, which is suitable when, for example, it is desired to change the monitoring location depending on the time.

Furthermore, when an alarm signal is supplied to 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 selects and outputs the video signal from the video camera corresponding to the number of the terminal to which the alarm signal is supplied with the changeover switch 2, and stores the number of the terminal to which the alarm signal is supplied and time data in the RAM 7b;
Furthermore, depending on the set operation mode, a warning sound is output from the speaker for a predetermined period of time, and a warning lamp is made to blink for a predetermined period of time. Therefore, for example, by arranging an infrared sensor at each monitoring location and supplying an alarm signal from the infrared sensor to the alarm input terminals 41 to 48 of each video signal switching device, it is possible to detect an intruder at each monitoring location. When the intruder is present, the video of the surveillance location where the intruder was located is automatically displayed on the monitor receiver 51, and the alarm circuit 9 warns of this, and for example, when the video of another surveillance location is displayed. Even if there is an intruder, the intruder will not be overlooked and can be monitored reliably. Also, instead of monitoring in real time with the monitor receiver 51,
When monitoring an unattended place at night, the presence of this intruder can be found later from the data stored in the memory device 7.

Furthermore, by canceling this automatic switching mode, a manual switching operation corresponding to the operation of the input selection switch 20 is performed. Here, for example, the operation when the input selection switch 20 corresponding to the first video input terminal 11 of the second video signal switching device 200 is pressed is shown in FIG.
This will be explained with reference to the flowchart No. 1. First, when the central control device 1 of the second video signal switching device 200 detects an operation of the input selection switch 20 corresponding to the first video input terminal 11 of this video signal switching device 200, a command is transmitted from the master. In response to this, the operation information for this switch is transmitted. Then, the central control device 1 of the master video signal switching device 100 determines the camera number corresponding to the operated switch based on the transmitted information. In this example, the camera number is 9, and control is performed to switch to the image of this camera number 9. That is, the first video input terminal 11 of the second video signal switching device 200 is selected by the changeover switch 2, and the corresponding input selection switch 2 of the second video signal switching device 200 is selected.
0 is turned on, and a character corresponding to camera number 9 is superimposed on the output video signal. In this way, manual switching control is performed while communication is being performed between the master and slave. Note that even when any input selection switch 20 is pressed in the automatic switching mode described above, switching is performed in the same procedure as in the flowchart of FIG. 11.

As described above, according to the video signal switching device of this example, when a plurality of video signal switching devices are connected, the switching operation is automatically performed in unison. Therefore, only eight video cameras can be connected to one video signal switching device, but by connecting four video signal switching devices, for example, 32 video cameras can be connected, and the images from each video camera can be connected. can be monitored. In this case, by simply setting one predetermined video signal switching device as the master, the other video signal switching devices automatically become slaves, and switching can be performed by commands from the central control device 1 of the master video signal switching device. Various operations such as these can now be performed, and there is no need for any setting work on the slave side. In particular, the input (camera) number of the video signal switching device on the slave side is automatically changed to one corresponding to the number of connected devices when connected to the master, and processing such as display at the time of switching is performed. There is no need to set the camera number using dip switches, etc., and connection work can be done easily. Also, sending commands from this master video signal switching device,
As shown in FIG. 3, the response to this command is sent to all the video signals handled by this video signal switching device within one vertical cycle, so the response to the input video is transmitted over two vertical cycles. There is no instruction for switching, etc., and the image is not distorted when switching. In other words, when each video signal switching device receives an instruction to switch the input video, it performs the switching in the next vertical blanking period, so all connected video signal switching devices switch within the same vertical blanking period. is performed, the switching timings match, and the image is not distorted during switching.

In the above embodiment, a video camera for monitoring is connected to all the video input terminals 11 to 19, but other video signal sources may be connected to the video input terminals. Furthermore, it goes without saying that the present invention is not limited to the above-mentioned embodiments, and can take various other configurations.

[0060]

[Effects of the Invention] According to the present invention, when a plurality of video signal switching devices are connected, switching operations are automatically performed as one unit, and a large number of locations can be monitored simultaneously with video cameras. . In this case, in particular, the input number of the video signal switching device on the slave side is automatically changed to one corresponding to the number of connected devices by connection with the master, and processing such as display at the time of switching is performed. There is no need to perform setting work using dip switches, etc., and it is possible to easily connect multiple video signal switching devices.

[Brief explanation of the drawing]

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

FIG. 2 is a connection diagram showing how the video signal switching device of one embodiment is used.

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

FIG. 4 is an explanatory diagram showing a command transmission state of an embodiment of the video signal switching device of the present invention.

FIG. 5 is an explanatory diagram showing a transmission state of a response to a command in an embodiment of the video signal switching device of the present invention.

FIG. 6 is an explanatory diagram showing a display state according to an embodiment of the video signal switching device of the present invention.

FIG. 7 is an explanatory diagram showing a display state according to an embodiment of the video signal switching device of the present invention.

FIG. 8 is an explanatory diagram showing a display state according to an embodiment of the video signal switching device of the present invention.

FIG. 9 is an explanatory diagram showing a display state according to an embodiment of the video signal switching device of the present invention.

FIG. 10 is a flowchart illustrating an embodiment of the video signal switching device of the present invention.

FIG. 11 is a flowchart illustrating an embodiment of the video signal switching device of the present invention.

[Explanation 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 Synchronous generator 100, 200, 300, 400 Video signal switching device 101-108, 201-208, 301-308, 4
01-408 Video camera

Claims (1)

[Claims] Claim 1: A video signal switching device that switches and outputs video signals supplied from a plurality of video signal sources to n input terminals (n is an arbitrary integer), wherein a plurality of the video signal switching devices are connected. At this time, one predetermined video signal switching device is set as the master, the other video signal switching devices are set as slaves, and the master video signal switching device side switches the above video signal switching devices of all the connected video signal switching devices. A video signal switching device in which a series of consecutive numbers are assigned to n input terminals, and a predetermined switching process is performed based on the assigned series of consecutive numbers.