JP4204688B2 - Video switching system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for switching and transmitting a plurality of video signals, and more particularly to a technique for transmitting a plurality of scattered video signals and other video signal outputs with fewer wires.
[0002]
[Prior art]
A system in which a plurality of television camera systems are selectively switched and centrally monitored requires a plurality of wirings corresponding to the number of inputs of the switching device, and the input video signals are often asynchronous with each other. The same applies to a routing switcher that selectively switches and outputs the outputs of a plurality of video devices.
[0003]
In the prior application (Japanese Patent Application No. 9-228262, unpublished at the time of filing this application), the applicant of the present application synchronizes the video signals of a plurality of television cameras and individually controls the output via the current drive. Thus, a technique for connecting to a signal transmission cable (hereinafter simply referred to as a cable) and enabling switching on the cable is proposed.
[0004]
FIG. 9 is a block diagram of the video transfer system of the embodiment of the prior application. In FIG. 9, one end of a coaxial cable 30 includes a synchronization signal generator 60, adapters 2 ₁ to 2 _n for connecting television cameras 3 _{1 to} 3 _n at a plurality of locations, and a video signal receiver 4. Connected.
[0005]
Adapter 2 ₁ to 2 _n has a current drive circuit, the video signal including no synchronizing signal is the output of which is connected to the coaxial cable 30 via the switch.
[0006]
The switches are individually closed and controlled by the control signal generated by the control signal generator 8 and transmitted during the vertical blanking period of the synchronization signal, and the video signals of the television cameras 3 _{1 to} 3 _n are selectively switched. It is connected to the coaxial cable 30 and is transmitted as a composite video signal superimposed on the synchronization signal.
[0007]
In the first embodiment of the prior application, the television cameras 3 _{1 to} 3 _n operate in synchronization with the synchronization signal of the synchronization signal generator 60 supplied via the adapters 2 ₁ to 2 _n , the adapter 2 ₁ to 2 _n in the example includes a frame memory, is performed synchronized by reading the video signal data by the synchronization signal written. As described above, the switching output of the asynchronous video signal can be dealt with the disturbance at the time of switching due to the asynchronous by controlling the writing and reading to the frame memory.
[0008]
[Problems to be solved by the invention]
In a surveillance system, etc., the installation locations of multiple television cameras are scattered over a wide range, the cable wiring is numerous and diverse, and the distance from the surveillance location where these video signal switching devices are installed is often long, It is necessary to lay many long cables in various directions. The same applies to the routing switcher. In relation to such a switching system that can be switched with a small number of cable wirings, the prior application that assumes switching in a synchronized state has the following problems.
[0009]
In FIG. 9, the synchronization with the television cameras 3 _{1 to} 3 _n or the synchronization with the adapters 2 ₁ to 2 _n having a frame memory is expensive. In general, a video signal output from a television camera is a composite video signal including a synchronization signal. However, in the prior application apparatus, since the synchronization signal from the synchronization signal generator 30 and the video signal not including the synchronization signals from the television cameras 3 _{1 to} 3 _n are individually output, the phase relationship between them is matched. A separate device is required.
[0010]
Further, it is desirable that an amplifier can be inserted in the middle of the cable for correction of frequency characteristics and characteristic impedance. However, in the prior application apparatus shown in FIG. 9, the images of the television cameras 3 _{1 to} 3 _n are used. Since the control signal is transmitted from the signal receiving side, if an amplifier is inserted, an amplifier having a function of discriminating and amplifying different signals in both directions is required. However, since such an amplifier is expensive and complex and large in terms of hardware, it is not possible to actually use it in a prior application device that aims to rationalize wiring facilities and reduce installation costs. Have difficulty.
[0011]
In a system in which a large number of television cameras are scattered over a wide range, it is desirable that a wide variety of long cables can be laid, for example, by connecting another coaxial cable as a branch line to the trunk line of the pair of coaxial cables 30. It is difficult to adopt such an embodiment because it is difficult to insert.
[0012]
The present invention has been made in such a background, and in the installation of television cameras and other video devices in which the installation locations are scattered and the wiring routes are diversified, the wiring facilities are rationalized and the installation cost is reduced. An object is to provide a video switching system that can be reduced.
[0013]
[Means for Solving the Problems]
The present invention is a video switching system for receiving wiring means, a plurality of adapters provided on the wiring means and including means for connecting the video signal output means, and a video signal output from the video signal output means. And a control signal generating means for sending a control signal including an identification code individually assigned to the adapter, wherein the adapter extracts the identification code from the control signal, and the video signal output means A current drive circuit that receives the video signal as an input, and the means for extracting comprises means for controlling the intermittentness of the output of the current drive circuit in accordance with the presence or absence of the identification code of the adapter included in the control signal. Video switching system.
[0014]
Here, the present invention is characterized in that the wiring means includes a pair of cables and electrical wiring, and the means for receiving the video signal is a video signal output from the adapter via the cable. The control signal generating means includes means for sending the control signal to the adapter via the electrical wiring. As the electrical wiring, a power supply wiring can be used.
[0015]
The wiring means is provided with a cable adapter for inputting a video signal transmitted to the cable to the current drive circuit, and the input of the current drive circuit of the cable adapter has a wiring means other than the wiring means. Means for controlling the interruption of the video signal output of the current drive circuit of the cable adapter in synchronization with the control of the interruption of the video signal output of the current drive circuit of the adapter provided in the other wiring means connected to the cable It can also be set as the structure provided with. Thereby, the cable used as a branch line can be laid in the cable used as a trunk line. At this time, in the present invention, since the control signal is transmitted not through the cable but through the electrical wiring, the signal transmitted to the cable is only a video signal, so that an amplifier with a simple configuration can be inserted. it can.
[0016]
The means for receiving the video signal comprises a frame memory, means for writing the data of the input video signal into the frame memory based on the vertical synchronization signal, and means for reading out the data of the input video signal by the reference synchronization signal; It is desirable to have a configuration comprising As a result, a video signal asynchronous to the reference synchronization signal can be input to the frame memory, and a video signal synchronized with the reference synchronization signal can be output when reading.
[0017]
As the video signal output means, a television camera can be assumed, but other than that, for example, instead of the television camera, various video material sources are connected, and this is used for various video images. By connecting to the processing device, the video switching system of the present invention can be used as a routing switcher.
[0018]
A circuit means corresponding to the adapter may be housed in the video signal output means. That is, the hardware configuration can be further simplified by incorporating the current drive circuit and the decode circuit provided in the adapter into a television camera or a video apparatus. Alternatively, the adapter can be attached to a television camera or a video device.
[0019]
That is, by terminating both ends of a pair of cables, such as ordinary coaxial cable, parallel cable or twisted pair cable, and connecting and transmitting the output signal from the current drive circuit with high impedance output from the middle of the cable, the characteristics of the cable A signal generated in the terminating resistor can be received without disturbing the impedance. This current drive circuit can be constituted by, for example, a transistor base ground circuit.
[0020]
If the video signal of the television camera output is connected to a plurality of locations of the cable via a current drive circuit, and the output is selectively selected by each intermittent control and connected to the cable, The video signal is switched on the cable.
[0021]
The connection of the current drive circuit to the middle of the cable is a short wiring that does not disturb the characteristic impedance, and connectors that lead out the wiring with crimp pins etc. from the middle of multi-core parallel cables etc. are also on the market, explained in the previous application did.
[0022]
In addition, an amplifier can be inserted in the middle of the cable for the purpose of correcting frequency characteristics or characteristic impedance. The input / output impedance is a load of the current drive circuit, and the cables are a pair of cables divided by the amplifier.
[0023]
If the television camera is scattered over a wide area and a pair of cables is insufficient, the cable is the main line as the first cable, and the same second or second cable is laid as a branch line, The reception signal of this branch cable is connected to the input of one of the current drive circuits of the first cable.
[0024]
The first cable is connected to the cable adapter as means for receiving a video signal for receiving a signal via the cable, and the video signal is amplified, or characters such as camera number and time are added, or image processing is performed. Etc. are output and connected to a display device such as a monitor or a recording device.
[0025]
Also, by writing the digitized input video signal to the frame memory based on the vertical synchronization signal and reading it with the reference synchronization signal, it is possible to prevent synchronization disturbance due to asynchronous switching.
[0026]
Each adapter is individually set with an identification code, and a means for extracting the identification code is connected to the current drive circuit of each adapter, and the means for extracting the self-identification code from the input control signal. By detecting this, intermittent control of the output of each current drive circuit connected to the cable is performed.
[0027]
When the second or second or subsequent cable is provided and the television camera connected to the cable is selected by switching control, at the same time, for connecting the cable to the first cable. Similarly, the current drive circuit of the cable adapter is selected by switching control, and the video signal of this cable is connected to the first cable.
[0028]
It is preferable that the cable is provided with electric wiring and connected to the control signal generating means, and the control signal is generated and output to be connected to the respective extracting means. It is preferable that the electrical wiring is superimposed on a control signal using a power supply wiring, and is received and separated again. Alternatively, the already-wired electric wiring for power supply can be used as it is connected to the control signal generating means. Thereby, it is not necessary to newly provide a wiring for transmission of the control signal, and the installation cost can be reduced.
[0029]
The means for generating the switching timing of the control signal may be an autonomous sequence, a manual control or a detection signal such as an abnormality by a sensor, and a signal for controlling the operation of each television camera. It can also be included.
[0030]
In the present invention, video signals of a plurality of television cameras are connected to a plurality of ordinary transmission cables even if they remain analog signals or are not synchronized without being digitized or modulated. The output of each television camera can be selected and switched individually with less cable wiring.
[0031]
The television camera connected to the cable may be a video device other than that, and can also be used as a routing switcher for switching and selecting various video signals.
[0032]
The current drive circuit provided in the adapter, the extracting means, and the connecting means can be housed in a television camera or video device. Alternatively, the adapter can be attached to the device.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the invention will be described with reference to FIGS. 1 to 5, 7, and 8. FIG. FIG. 1 is a block diagram showing the main part of a video switching system according to the present invention. FIG. 2 is a block diagram of the main part of the adapter. FIG. 3 is a block diagram of the main part of the video switching system of the present invention provided with a trunk line and a branch line. FIG. 4 is a block diagram of the main part of the cable adapter. FIG. 5 is a diagram for explaining the operation of the frame memory. FIG. 7 is a diagram showing an example in which the video switching system of the present invention is used as a routing switcher. FIG. 8 is a diagram showing an adapter built in the television camera.
[0034]
The present invention is a video switching system, and as shown in FIG. 1, a plurality of cables 1 and electrical wiring 9, and a plurality of television cameras 3 _{1 to} 3 _n provided on the cable 1 and electrical wiring 9 are connected. control including an adapter 2 ₁ to 2 _n, and the video signal receiving apparatus 4 that receives a video signal outputted from the television camera 3 ₁ to 3 _n, the identification code assigned individually to the adapter 2 ₁ to 2 _n As shown in FIG. 2, the adapters 2 ₁ to 2 _n include a decoding circuit 22 that extracts the identification code from the control signal, and a television camera 3 ₁ to 3. 3 _n and a current drive circuit 21 which receives the video signal, the decoding circuit 22, intermittent output of the current drive circuit 21 in accordance with the presence or absence of the identification code of the own adapter included in the control signal A video switching system controlled.
[0035]
Here, it is an aspect of the present invention, the video signal receiving apparatus 4 receives the video signal output from the adapter 2 ₁ to 2 _n via the cable 1, the control signal generator 8, the electric The control signal is sent to the adapters 2 ₁ to 2 _n via the wiring 9.
[0036]
Further, as shown in FIG. 3, the adapter 2 _3, and a cable adapter to the video signal transmitted to the cable with the input of the current drive circuit 21, as shown in FIG. 4, the cable adapter 2 ₃ current A cable 16 is connected to the input of the drive circuit 21 via the termination resistor 12 and the buffer amplifier 11, and the video signal output of the current drive circuit 21 of the adapters 13 ₁ and 13 _n provided in the cable 16 is controlled to be intermittent. by performing intermittent control of the video signal output of the synchronization with the adapter 2 ₃ current drive circuit 21, it is possible to realize an embodiment in which the cable 16 and branch cables 1 as trunk. Note that the cable adapter 2 ₃ The other adapter hardware configuration is the same.
[0037]
As shown in FIG. 5, the video signal receiving device 4 includes a frame memory 40, and writes the data of the input video signal to the frame memory 40 based on the vertical synchronization signal, and the data of the input video signal is based on the reference synchronization signal. By reading, a video signal asynchronous with the reference synchronization signal output from the television cameras 3 _{1 to} 3 _n can be made a video signal synchronized with the reference synchronization signal.
[0038]
Further, as shown in FIG. 7, not only the television camera, and connect the various video apparatus A~D adapter 2 ₁ to 2 _n, not only the display device 5, the image various video processing apparatus E~F A routing switcher can be realized by connecting to the signal receiving device 4.
[0039]
Further, as shown in FIG. 8, a current drive circuit 21 and a decode circuit 22 which are circuit means corresponding to an adapter may be housed in a television camera apparatus.
[0040]
【Example】
(First Example)
A first embodiment of the present invention will be described. As shown in FIG. 1, adapters 2 ₁ to 2 _n to which television cameras 3 _{1 to} 3 _n are connected are connected to a plurality of locations of the cable 1 and the electrical wiring 9 attached thereto, and both ends of the cable 1 are connected. Are terminated by terminating resistors 6 and 7, and a control signal generator 8 is connected to the electrical wiring 9 to output a video signal switching control signal.
[0041]
In the middle of the cable 1, an amplifier 10 is inserted toward the video signal receiving device 4 that corrects the deterioration of the video characteristics due to the cable 1, but this may not be necessary depending on the length or impedance characteristics of the cable 1.
[0042]
2, the video signal output of the television camera 3 ₁ is input to the current drive circuit 21 according to the base circuit of a transistor or the like provided in the adapter 2 _1, in the video signal output an output of the decoding circuit 22 By the interruption control of this signal by the switch to be controlled or the electronic switch or the electronic circuit, the output is controlled to be connected to the cable 1.
[0043]
In this output intermittent control, a control signal of the electric wiring 9 is inputted, and the own identification code is detected by the decoding circuit 22 with a unique identification code, whereby the current drive circuit 21 is individually switched and controlled. It may be added signal for controlling the operation of the television camera 3 ₁ to the control signal.
[0044]
By thus video output of the adapter 2 ₁ to 2 _n are individually controlled intermittently, the video output of the television camera 3 ₁ to 3 _n are alternatively selected switching.
[0045]
In FIG. 1, the electrical wiring 9 may be a composite cable including the cable 1, a multi-core parallel cable, or the like, or the control signal superimposed on the electrical wiring for power supply. The control signal generated by the control signal generator 8 is autonomous. A switching signal based on detection of an automatic sequence or manual control or detection of an abnormal signal of a sensor or the like may be used.
[0046]
The received signal generated in the terminating resistor 7 via the cable 1 is input to the video signal receiving device 4 and is converted into a digital signal in order to prevent the disturbance of synchronization when the asynchronous video signal is switched as shown in FIG. Write to the frame memory 40 based on the synchronization signal, read based on the reference synchronization signal, and return to the analog signal again.
[0047]
It is also possible to superimpose character information such as camera number and time corresponding to the switching video signal, and the video output of the video signal receiving device 4 is connected to the display device 5 and displayed as an image. This may be a recording device.
[0048]
Further, the video signal receiving device 4 and the control signal generating device 8 can be housed in the same case.
[0049]
(Second embodiment)
A second embodiment of the present invention will be described with reference to FIGS. Respect except codes 11 to 17 in FIG. 3 has been described in the first embodiment, in the second embodiment the adapter 2 ₃ in FIG. 1 is connected another cable 16.
[0050]
Adapters 13 _{1 to} 13 _n to which television cameras 14 _{1 to} 14 _n are connected are connected to a plurality of locations of the cable 16 and the electrical wiring 9 attached thereto, and termination resistors 12 and 17 are connected to both ends of the cable 16. It is, as shown in FIG. 4, the received signal via the cable 16 is connected to the adapter 2 ₃ through a buffer amplifier 11.
[0051]
The adapters 13 _{1 to} 13 _n are the same as the adapters 2 ₁ to 23 _3, and are selected by controlling the video signal output of the television cameras 14 _{1 to} 14 _n individually and intermittently under the control of the control signal of the electric wiring 9. It is switched and connected to the cable 16.
[0052]
In this case the adapter 2 ₃ is connected only selected simultaneously controlled to the cable 1 when one of the adapter 13 ₁ to 13 _n is connected is selected controlled.
[0053]
(Third embodiment)
A third embodiment of the present invention will be described with reference to FIG. FIG. 6 is a conceptual diagram showing a configuration in which a plurality of video switching systems of the present invention are used in one television camera. A plurality of devices connected as shown in FIG. 1 or FIG. 3 except for the television cameras 3 _{1 to} 3 _n are provided. As shown in FIG. 6, a plurality of devices provided corresponding to the set of television cameras 3 ₁ are provided. It is also possible to connect the adapters (# 1 to #m) 2 _1-1 to 21 _-m of the type device in parallel.
[0054]
In this case, the plurality of control signal generators (# 1 to #m) 8 ₁ to 8 _m generate their respective control signals, so that the video signals controlled and selected by the respective control signals are the respective video signals. Receiving devices (# 1 to #m) 4 ₁ to 4 _m receive the signals. The plurality of control signal generators (# 1 to #m) 8 ₁ to 8 _m and the video signal receivers (# 1 to #m) 4 ₁ to 4 _m may be combined together.
[0055]
(Fourth embodiment)
A fourth embodiment of the present invention will be described with reference to FIG. Video signal output apparatus connected to the adapter 2 ₁ to 2 _n is not necessarily limited to the television cameras, as shown in FIG. 7, it may be another imaging device to D. By adopting such an embodiment, the video switching system of the present invention can be used as a routing switcher. In this case, the output of the video signal receiving device 4 is not limited to the display device 5 and is connected to various video processing devices EG. In some cases, the routing switcher does not need to prevent synchronization disturbance by the frame memory as described above.
[0056]
(Fifth embodiment)
A fifth embodiment of the present invention will be described with reference to FIG. As shown in FIG. 8, the adapter 2 ₁ to 2 current drive circuit 21 and the decoding circuit 22 is housed circuit means _n may be housed in a device of a television camera. Alternatively, even in the video device other than the television camera it can also be used to accommodate the current drive circuit 21 and the decoding circuit 22 is a circuit means which is housed in the adapter 2 ₁ to 2 _n in the device. Alternatively, it is possible to use integrated mounting the adapter 2 ₁ to 2 _n to the device housing.
[0057]
【The invention's effect】
As described above, according to the present invention, it is possible to rationalize the wiring equipment and reduce the installation cost when installing television cameras and other video apparatuses in which installation locations are scattered and wiring routes are diversified. .
[Brief description of the drawings]
FIG. 1 is a main part configuration diagram of a video switching system according to the present invention.
FIG. 2 is a block diagram of the main part of the adapter.
FIG. 3 is a configuration diagram of a main part of a video switching system according to the present invention including a trunk line and a branch line.
FIG. 4 is a block diagram of a main part of a cable adapter.
FIG. 5 is a diagram for explaining the operation of the frame memory;
FIG. 6 is a conceptual diagram showing a configuration in which a plurality of video switching systems of the present invention are used in one television camera.
FIG. 7 is a diagram showing an example in which the video switching system of the present invention is used as a routing switcher.
FIG. 8 is a diagram showing an adapter built in the television camera.
FIG. 9 is a configuration diagram of a video transfer system according to an embodiment of the prior application.
[Explanation of symbols]
1,16 cable _{2 1 ~2 n, 2 1-1 ~2} 1-m, 13 1 ~13 n adapter _{3 1 ~3 n, 14 1 ~14} n television camera 4, 4 ₁ to 4 _m video signal Receiving device 5 Display devices 6, 7, 12, 17 Terminating resistors 8, 8 ₁ to 8 _m Control signal generator 9 Electrical wiring 10 Amplifier 11 Buffer amplifier 15 Switching device 18 Console 21 Current drive circuit 22 Decoding circuit 30 Coaxial cable 32 Shield 33 Core 40 Frame memory 50 Television camera circuit section 60 Synchronous signal generator

Claims (4)

Wiring means, a plurality of adapters provided in the wiring means and including means for connecting the video signal output means, means for receiving the video signal output from the video signal output means, and the adapter individually assigned Control signal generating means for transmitting a control signal including the identification code, wherein the adapter extracts the identification code from the control signal, and the current drive circuit receives the video signal of the video signal output means as input. In the video switching system, the means for extracting includes means for controlling on / off of the output of the current drive circuit in accordance with the presence or absence of an identification code of its own adapter included in the control signal. A pair of signal transmission cables and electrical wiring, and the means for receiving the video signal is connected to the adapter via the signal transmission cable. Comprising means for receiving the video signal outputted from said control signal generating means includes means for sending the control signal to the adapter via the electrical wiring,
The wiring means is provided with a cable adapter for inputting a video signal transmitted to the signal transmission cable to the current drive circuit. The input of the current drive circuit of the cable adapter includes other than the wiring means. The signal transmission cable of the wiring means is connected, and the video signal output of the current drive circuit of the cable adapter is synchronized with the intermittent control of the video signal output of the current drive circuit of the adapter provided in the other wiring means. A video switching system characterized by comprising means for intermittent control .   The video switching system according to claim 1, wherein the electrical wiring is a power supply wiring. The means for receiving the video signal comprises a frame memory, means for writing the data of the input video signal into the frame memory based on the vertical synchronization signal, and means for reading out the data of the input video signal by the reference synchronization signal; The video switching system according to claim 1, further comprising: 2. A video switching system according to claim 1 , wherein circuit means corresponding to said adapter is accommodated in said video signal output means .

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