JP3278719B2 - Information signal selection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information signal selecting method for transmitting an electric video signal from a plurality of transmitting means to each of a plurality of receiving means and selectively receiving the transmitted video signal at each receiving means. Related to the device.

[0002]

2. Description of the Related Art In a surveillance television system used as one of information transmission systems, an electric switch is used as a means for selectively connecting at least one monitor or video recorder to one of a plurality of television cameras. Have been. The electrical switch is used to sequentially connect and connect a plurality of television cameras to a monitor or a video recorder in order to display images from the television cameras on a monitor or sequentially record the images on the video recorder.

However, in a known electronic switch used in this type of system, the larger the number of transmitting means and receiving means, the larger the software for switching control becomes, the more expensive it becomes. Work becomes complicated. Furthermore, since the known electronic switch does not employ a synchronization signal processing function at the time of switching, the video displayed on the monitor during and immediately after the switching operation from one television camera to another television camera. In many cases, reproduced images are disturbed by signals. As means for preventing such disturbance of the reproduced image, it is known to use, for example, a device for generating a vertical or horizontal synchronization signal or a device for generating a composite synchronization signal. Further, there is also known an apparatus in which a generated synchronization signal is sent to each camera to synchronize, or a deflection circuit of the camera is driven using these synchronization signals. For example, a device for forcibly synchronizing by mixing a stronger external synchronization signal with the video signal of each TV camera, for example,
It is described in U.S. Pat. No. 4,603,352 and is well known.

[0004]

In any of the above methods, the generated synchronization signal is a continuous pulse signal, and is susceptible to external noise. To avoid the influence of such external noise, use a coaxial cable that is strictly shielded so as not to be affected by external noise. Has adopted. The present invention eliminates central control of an electronic switch for switching between a transmitting unit and a receiving unit to be connected without disturbing a reproduced image even if the number of transmitting units and receiving units is large, and a simple device. A main object of the present invention is to obtain an information signal selecting device capable of easily switching between a transmitting means and a receiving means. Further, the present invention multiplexes a video signal with a signal for identifying each of the transmitting / receiving means and an audio signal. An information signal selection device to be converted is also included in the object of the invention.

[0005]

In order to achieve the object of the present invention as described above, in the invention according to claim 1 of the present application, an information signal selecting device processes an electrical information signal including a video signal. A plurality of transmitting means, a plurality of receiving means for selectively receiving the video signal, and a plurality of connecting each receiving means to the plurality of transmitting means and transmitting an information signal from which an external synchronization signal has been removed. An information transmission line, generating an external synchronization signal, and transmitting the external synchronization signal to the plurality of transmission lines by using a transmission line dedicated to external signal transmission provided separately from the information transmission line provided between a plurality of transmission / receptions; Means and an external synchronizing signal generating means for supplying the plurality of receiving means, wherein each of the plurality of transmitting means transmits the information signal obtained by removing the external synchronizing signal from the information signal to the information transmission line. Via Each of the plurality of receiving means includes one or more of the information transmission lines and a selection circuit for switching between the information transmission lines, and the selection circuit provided in the reception means. The information transmission line is switched in a vertical flyback period in synchronization with an external synchronization signal, and a video signal is added to the information signal.
A plurality of video signal generating means corresponding to the transmitting means and supplying a video signal thereto, wherein each of the plurality of video signal generating means is synchronized by a timing of an external synchronization signal transmitted from the transmitting means. And supplying the video signal to a corresponding transmitting means, and at least one of the receiving means performs recording and reproduction of the video signal included in the information signal transmitted from the selecting circuit. Processing means,
The external synchronizing signal has a level higher than the highest voltage of the video signal or lower than the lowest voltage of the video signal, and each transmitting means transmits an external synchronizing signal to the information transmission line between the transmitting means and the video signal generating means. And a circuit for removing an external synchronization signal from the information signal sent from each transmitting means to each receiving means.

In the invention according to claim 2 of the present application, claim 1
In the invention according to the first aspect, each of the video signal generating units further compares the signal level of the pulse signal with a reference signal having a predetermined voltage level to extract the external synchronization signal, and outputs the extracted external synchronization signal to the internal signal. An information signal selection device comprising a comparison circuit for supplying a synchronization signal generation circuit is provided.

In the invention according to claim 3 of the present application, claim 1
In the invention according to any one of (1) to (2), each video signal generation means further generates an identification code signal corresponding to the identification code assigned to the video signal generation means, and transmits the identification code signal to the transmission means. An identification code signal generation circuit inserted into a video signal to be output, wherein the at least one receiving means further extracts the identification code signal in a signal output from the selection circuit and corresponds to the extracted identification code signal An information signal selecting device for providing an identification code signal processing means for outputting a signal to be processed to the video signal processing means.

In the invention according to claim 4 of the present application, claim 3
In the invention according to the above, the identification code signal processing means,
A memory for storing data relating to each identification code signal; an extraction circuit for extracting and decoding the identification code signal in the signal output from the selection circuit to generate a decoder signal; A controller that searches the memory and superimposes the searched data on the video signal.

In the invention according to claim 5 of the present application, claim 2
In one of the inventions according to the first to fourth aspects, further, a control signal including a coded control instruction for controlling the video signal generating means is transmitted to an identification code signal corresponding to an identification code assigned to each video signal generating means. And control means for generating a circuit corresponding to the control signal only when the associated identification code signal corresponds to the identification code signal permitted to the video signal generation means. An information signal selection device provided to the video signal generation means is provided.

In the invention according to claim 6 of the present application, claim 5
In the invention according to the aspect, the control signal is inserted into a video signal transmission line connecting the video signal generation unit to the transmission unit, and the video signal generation unit further transmits the control signal from the video signal transmission line. Extracting and extracting the extracted control signal when the associated identification code signal corresponds to the identification code allowed by the video signal generating means;
An information signal selecting device is provided, which includes a control signal processing unit that supplies a control signal to a circuit corresponding to the extracted control signal.

In the invention according to claim 7 of the present application, claim 1
In one of 6 to 6, each transmitting means further generates a multiplexed signal of the video signal and the audio signal by inserting the audio signal into the video signal, and transmits the multiplexed signal to a plurality of information transmission lines corresponding thereto. An information signal selection device is provided, comprising an output signal combining means.

In the invention according to claim 8 of the present application, claim 1
In one of 6 to 6, each video signal generating means further generates a multiplexed signal of a video signal and an audio signal by inserting an audio signal into the video signal, and supplies the multiplexed signal to the corresponding transmitting means. An information signal selecting device is provided, comprising:

According to the ninth aspect of the present invention, the seventh aspect is provided.
(8) In the information signal selecting device described in (8), each receiving means further includes an audio signal recovery means for recovering and outputting an audio signal from the multiplexed signal.

In the invention according to claim 10 of the present application, in the invention according to claim 5, each of the receiving means further transmits the control signal in a direction opposite to a propagation direction of the video signal. Each transmission means further includes a control signal extractor for extracting the control signal from the information transmission line and supplying the extracted control signal to a corresponding video signal generator. An information signal selection device is provided.

According to an eleventh aspect of the present invention, in addition to the first aspect, a transmission line selection signal for designating an information transmission line to be selected is supplied to the selection circuit.
An information signal, comprising: a control unit provided for each of the reception units; and a master control unit that outputs a code indicating a selectable information transmission line and a non-selectable information transmission line to the control unit. Provide a selection device.

According to a twelfth aspect of the present invention, in the first aspect of the present invention, a control code for instructing on / off of each device forming the video signal generating means, wherein the information transmission line is A control unit that outputs a control code to be supplied to the video signal generation unit to the selection circuit via the control unit, and a code that indicates a selectable information transmission line and a non-selectable information transmission line. An information signal selecting device, comprising: a master control unit that outputs the information signal to the control means.

According to a thirteenth aspect of the present invention, in addition to the first aspect, a transmission line selection signal for designating an information transmission line to be selected and an on / off state of each device forming the video signal generating means are further provided. A control code for instructing off, a control code to be supplied to the video signal generation means via the information transmission line to the selection circuit, and a control means arranged for each of the reception means; An information signal selection device, comprising: a master control unit that outputs a code indicating an information transmission line and an unselectable information transmission line to the control unit.

In the invention according to claim 14 of the present application, in one of claims 12 and 13, the master control unit further connects each of the control circuits of the receiving means to the plurality of information transmission lines. An information signal selecting device for controlling each of the selected video signal generating means.

[0019]

FIG. 1 shows an embodiment of an information signal transmitting device, that is, an information signal selecting device 10 in which the present invention is applied to a closed circuit television system such as a monitoring system. The information signal handled by the information signal selection device 10 is:
At least a video signal is included. The video signal is a composite video signal in the following description, but may be a simple video signal.

Referring to FIG. 1, an information signal selecting device 10
A plurality of transmitting devices 12 for transmitting information as electrical information signals, a plurality of receiving devices 14 for receiving the transmitted information signals, a plurality of information transmission lines 16 for transmitting the information signals, A plurality of television cameras 18 corresponding to and outputting video signals to the corresponding transmitting device 12
And an external synchronization signal generating circuit 20 for synchronizing the television camera, and a control circuit 22 for outputting a control command to the transmitting device 12 and the receiving device 14.

Each information transmission line 16 corresponds to a combination of the transmission device 12 and the reception device 14. For this reason, each transmitting device 12 is connected to all the receiving devices 14 by a plurality of information transmission lines 16 extending from the transmitting device 12,
Each receiving device 14 is connected to all the transmitting devices 12 by a plurality of information transmission lines 16 extending from the receiving device 14. Therefore, the information transmission line 16 is
And the number corresponding to the product of the number of receivers 14 and the number of receivers 14.

The transmission device 12, the reception device 14, the information transmission line 16, the external synchronization signal generation circuit 20, and the control circuit 22
Is located in the monitoring room. On the other hand, each television camera 18 is arranged at a monitored location. The corresponding transmitting device 12 and the television camera 18 are connected by a video signal transmission line 24 such as a coaxial cable.

Each transmitting device 12 receives a video signal from a corresponding television camera 18 via a video signal transmission line 24 into a transmission circuit 26, and uses the received video signal as an information signal by a driver 28 to transmit the information transmission line 16 Is transmitted to each receiving device 14 via the. Therefore, the driver 28 functions as a distribution circuit that distributes the information signal to the plurality of information transmission lines 16. The driver 28 can be, for example, a buffer using a transistor.

Each receiving device 14 receives an information signal transmitted from a plurality of transmitting devices 12 by a selection circuit 30 including an electronic switch circuit such as a multiplexer, and selects one of the plurality of information transmission lines 16. . Thus, the information signal transmitted by the selected information transmission line 16 is supplied to the receiving circuit 32.

The frequency of the external synchronization signal P1 is related to the vertical frequency of the video signal generated by the television camera 18, and can be either the frame scanning frequency or the field scanning frequency. For example, in the case of the NTSC system, since the frame scanning frequency is 30 Hz and the field scanning frequency is 60 Hz, the external synchronization signal is a frame external synchronization pulse of 30 Hz or 60 Hz.
Field external synchronization pulse.

As shown in FIG. 2A, the external synchronization signal P
1 is generated at a timing such that it falls within a vertical blanking period, preferably a period corresponding to a vertical blanking period, of a video signal transmitted from the television camera 18. Thus, the external synchronization signal can be transmitted using the video signal transmission line 24 in common with the video signal without affecting the video signal. Further, in order to avoid an input error of the signal level, it is preferable that the voltage level of the external synchronization signal P1 is higher than the white level Vw of the video signal. However, the voltage level of the external synchronization signal P1 may be lower than the black level Vb, preferably the pedestal level of the video signal.

In the following description, a frame external synchronization pulse having a voltage level higher than the white level of the video signal, particularly a frame external synchronization pulse corresponding to the phase of the second field, is used as the external synchronization signal P1.

In the illustrated example, each television camera 18 is a television camera that operates in synchronization with the external synchronization signal P1. Such a television camera uses an external synchronization signal having a voltage level larger than a white level of a video signal (or a voltage level smaller than a black level) as described in, for example, US Pat. No. 4,603,352. A well-known synchronized television camera can be used.

Each television camera 18 has an identification code allowed for that television camera 18. As the identification code, for example, numbers such as 1, 2, 3,... N can be used.

An information transmission line 16 extending from each transmission device 12
Is preferably bound on the side of the transmitting device 12 by a bracket or the like, and the information transmission line 16 extending from each receiving device 14 is bound by a bracket or the like on the receiving device 14 side.

As shown in FIG. 3, each transmission circuit 26 generates a pulse signal P2 shown in FIG. 2B, that is, a timing signal P2 based on the external synchronization signal P1 supplied from the external synchronization signal generation circuit 20 of FIG. And an external synchronizing signal insertion circuit 3 for inserting the external synchronizing signal P1 output from the pulse shaping timing circuit 34 into the video signal transmission line 24.
And an external synchronization signal that outputs the video signal from which the external synchronization signal P1 has been removed to the driver by clipping the external synchronization signal P1 in the signal supplied by the video signal transmission line 24 using the timing signal P2. And a clip circuit 38.

The external synchronizing signal clipping circuit 38 is shown in FIG.
The signal shown in FIG. 2A is received from the video signal transmission line 24, and the timing signal P2 shown in FIG. The signals P1 and P2 have a predetermined duty cycle and voltage level, are adjusted to a timing or phase within a vertical blanking period, preferably within a vertical blanking period of the video signal, and Generated every second field vertical sync pulse.

The external synchronizing signal clipping circuit 38 uses the timing signal P2 to determine the signal level of a part in the signal supplied to one input terminal and corresponding to the external synchronizing signal P1, using the timing signal P2. Black level Vb or lower. As a result, as shown in FIG. 2C, the external synchronization signal P1 is
It is removed from the composite video signal transmitted to the receiving device 14.

Thus, even if the external synchronizing signal P1 is included in the video signal supplied to the external synchronizing signal clipping circuit 38, the external synchronizing signal P1 is the video signal output from the external synchronizing signal clipping circuit 38. External synchronization signal P
1 is essentially removed by the external sync signal clipping circuit 38 so as not to include a one. However, video signal transmission line 2
The external synchronization signal P <b> 1 inserted in 4 is transmitted from the transmission device 12 to the corresponding television camera 18 via the video signal transmission line 24.

When the television camera 18 also generates an audio signal, the audio signal may be supplied to the driver 28, and the audio signal may be transmitted to the receiving device together with the video signal. In this case, the audio signal may be supplied to the transmission device 12 using the transmission line 40, or may be supplied to the transmission device 12 using the video signal transmission line 24.

When an audio signal is supplied to the transmitting device 12 using the transmission line 40, a synthesizing circuit 42 for synthesizing the video signal and the audio signal is disposed between the external synchronizing signal clipping circuit 38 and the driver 28. . However, when the audio signal is supplied to the transmitting device 12 using the video signal transmission line 24, the synthesizing circuit 42 is unnecessary because the video signal and the audio signal are already synthesized, and the external synchronizing signal clipping circuit 38 May be supplied to the driver 28.

Each transmission circuit 26 also includes a control signal generator 44 for controlling the corresponding television camera 18. The control signal generator 44 includes a synchronization separation circuit 46 for separating the horizontal and vertical synchronization signals H and V from the video signal transmitted through the video signal transmission line 24, and a control circuit shown in FIG. Using a control command supplied from the circuit 22 to the transmission line 48, a control signal generation circuit 50 that outputs a control signal for operating the corresponding television camera 18 at a predetermined timing, and a separated synchronization signal H, V A counter 52 for counting the number of horizontal scans for each frame scan or field scan based on the count, and a gate signal generating circuit 54 for generating a gate signal when the count value of the counter 52 is a predetermined value.
And the control signal generation circuit 5
And a gate circuit 56 for inserting a control signal output from 0 into the video signal transmission line 24.

The control command supplied to the transmission line 48 is a control code for instructing ON / OFF of a power source, a wiper, a tilting, a panning, a zoom, or the like, or a start command and a stop command for transmitting a video signal. The control signal is a signal in which a control code corresponding to the control command and an identification code assigned to each television camera 18 are combined. The gate circuit 56 controls a vertical blanking period of the video signal, preferably a vertical blanking period. The timing at which the external synchronization signal is inserted into the video signal transmission line 24 at a predetermined timing is different from the timing at which the external synchronization signal is inserted into the video signal transmission line 24.

The transmission line 48 may be provided for each television camera, that is, for each transmission device, or may be commonly used for a plurality of transmission devices. When the transmission line 48 is commonly used by a plurality of transmitting devices 12, the control command includes a control code specifying the content of the control and a device code specifying the transmitting device,
Each transmitting device 12 includes a circuit that determines whether the transmitted device code matches the device code assigned to the transmitting device 12.

The control signal generating circuit 50 outputs a control signal when the device code supplied to the transmission line 48 matches the device code assigned to the transmitting device. The identification code of the corresponding television camera may be used as the device code. Further, the control command may be directly transmitted from the control circuit 22 to each television camera 18.

As is apparent from the above, the external synchronization signal and the control signal are transmitted from each transmitting device 12 to the corresponding television camera 18 via the video signal transmission line 24.

However, instead of transmitting a control signal including a control code and an identification code to the television camera 18 via the video signal transmission line 24, a transmission line 5 dedicated to the control signal is used.
8. The control signal may be transmitted using another transmission line such as a transmission line 40 for voice signals, a telephone line, or the like. Transmission lines 40, 4
As 8, a twisted pair wire, an optical fiber wire, or the like may be used. When a transmission line dedicated to the control code and the identification code is provided, only the control code may be transmitted from the transmitting device to the corresponding television camera.

Similarly, instead of transmitting the external synchronization signal P1 to the television camera via the video signal transmission line 24, a transmission line dedicated to the external synchronization signal P1, a transmission line 40 for the audio signal,
The external synchronization signal P1 may be transmitted using another transmission line such as the control signal transmission line 58.

As shown in FIG. 4, each TV camera 18
Is a reference voltage source 60 for generating a reference voltage having a predetermined voltage level;
A level comparing circuit 62 that compares the voltage level of the external synchronization signal transmitted via the reference voltage source with a reference voltage supplied from the reference voltage source 60 and generates a pulse signal P3 when both voltage levels have a predetermined relationship; Internal synchronization signal generation circuit 6 for generating internal synchronization signals Hi and Vi synchronized with signal P3
And a video signal generating circuit 6 for outputting a video signal synchronized with the internal synchronization signals Hi and Vi to the video signal transmission line 24.
6, an audio signal generation circuit 68 for generating an audio signal corresponding to the video signal, and an audio signal insertion circuit 70 for inserting the audio signal into the transmission line 40.

As shown in FIG. 2A, when using an external synchronizing signal having a voltage level higher than the white level of the video signal, the level comparing circuit 62 determines whether the voltage level of the external synchronizing signal is equal to the reference voltage. When it is higher, that is, when it receives an external synchronization signal, it generates a pulse signal P3. However, when an external synchronization signal having a voltage level smaller than the black level of the video signal is used, the level comparison circuit 62
Generates a pulse signal P3 when the voltage level of the external synchronization signal is equal to or smaller than the reference voltage.

The internal synchronizing signal generating circuit 64 receives the pulse signal P3 output from the level comparing circuit 62, and generates horizontal and vertical internal synchronizing signals Hi and Vi synchronized with the received pulse signal P3. Video signal generation circuit 66
Receives horizontal and vertical internal synchronization signals Hi and Vi, shoots a subject in synchronization with the received internal synchronization signals,
A composite video signal corresponding to the photographed subject is generated. Thereby, the phase of the external synchronization signal corresponds to the phase of the composite video signal.

When transmitting the audio signal using the transmission line 40 instead of transmitting the audio signal using the video signal transmission line 24, the audio signal insertion circuit 70 may not be provided.

As shown in FIG. 4, each TV camera 18
In addition, an identification code permitted for the television camera 18 is set, and the set identification code is converted using the internal synchronization signals Hi and Vi into a blanking period of a video signal, preferably vertical blanking. And an identification code setting circuit 72 for outputting the identification code output from the identification code setting circuit 72 into the video signal transmission line 24 at a predetermined timing during the vertical blanking period. 74.

The identification code inserted into the video signal transmission line 24 by the identification code insertion circuit 74 is the same as the identification code transmitted to the television camera 18 together with the control code from the transmission circuit 26 shown in FIG. May be different from the identification code transmitted from the transmission circuit 26 to the television camera 18 together with the control code.

The timing at which the identification code insertion circuit 74 inserts the identification code into the video signal transmission line 24 is different from the timing at which the transmission circuit 26 shown in FIG. 3 inserts the external synchronization signal and control signal into the video signal transmission line 24. To do so, for example, the timing at which the transmission circuit 26 inserts the external synchronization signal and the control signal into the video signal transmission line 24 is set within the blanking period of the video signal, preferably within the vertical blanking period, respectively. Preferably, the predetermined time is one or more horizontal scanning periods within the vertical blanking period, and the timing at which the television camera inserts the identification code into the video signal transmission line 24 is within the blanking period of the video signal, preferably the vertical blanking period. Of these, it is more preferable that the time period be within one or more other horizontal scanning periods within the vertical blanking period.

The electric signal corresponding to the identification code inserted into the video signal transmission line 24 is a signal in the form of a binary code or a bar code having two or more voltage levels. As a voltage level of a signal corresponding to such an identification code, for example, as shown in FIG. 5A, a white level which is a maximum voltage level of a video signal in a video signal generated by a television camera, that is, a high level, The change in the amplitude of the pulse signal, such as the level “H”, the minimum voltage level black level or low level “L”, and the intermediate voltage level green level or intermediate level “M” can be used.

However, as shown in FIG. 5B, a change in pulse width may be used as an electric signal corresponding to the identification code. Further, as an electric signal corresponding to the identification code, as shown in FIG. 5C, either a sine wave signal or a pulse signal having a frequency corresponding to the identification code may be used. Such a sine wave signal or pulse signal may occur during one or more horizontal scanning periods of the video signal.

The signal corresponding to the control code output from the control signal generation circuit 50 shown in FIG. 3 can be a signal similar to the identification code as described above. However, the signal corresponding to the control code and the signal corresponding to the identification code may be different types of electric signals.

Each of the television cameras 18 further includes a code extraction circuit 7 for extracting a control code and an identification code transmitted from the control signal generation circuit 50 shown in FIG.
6, extracted identification code and identification code setting circuit 72
And a code comparison circuit 78 that outputs a match signal when the two codes match, a control code in the output signal of the code extraction circuit 76 is read using the match signal, and its control is performed. And a decoder 80 for outputting a control command corresponding to the code.

As the code extracting circuit 76, for example, based on the horizontal internal synchronizing signal Hi and the vertical internal synchronizing signal Vi,
A counter for counting the horizontal internal synchronizing signal for each field or frame scan of the video signal; and a video signal transmission line 24 when the count value is a predetermined value for the control signal.
And a code reproducing circuit that reproduces a control code and an identification code of the signal output from the gate circuit.

As the code reproducing circuit, a level sensor for reproducing the control code and the identification code by sensing the level, envelope, frequency, and phase according to the form of the electric signal corresponding to the control code and the identification code, An envelope detector, a frequency detector, a phase detector, and the like can be used.

The code comparing circuit 78 generates a coincidence signal when the reproduced code supplied from the code extracting circuit 76 corresponds to the setting code supplied from the identification code setting circuit 72, and is supplied from the code extracting circuit 76. When the reproduction code does not correspond to the setting code supplied from the identification code setting circuit 72, a mismatch signal is generated.

When using the control code and the identification code having the signal waveforms shown in FIG. 5 (A) or FIG. 5 (B),
For example, as shown in FIG. 6, the code extracting circuit 76 includes a synchronizing signal separating circuit 82 for extracting horizontal and vertical synchronizing signals in the composite signal transmitted from the television camera 18 and a number of horizontal scanning lines of the television camera for each vertical scanning. , A gate circuit 86 for outputting the composite signal transmitted from the television camera 18 only while the count value of the H synchronization signal counter 84 is a predetermined value, and the gate circuit 86
And a level sensor 88 for detecting the level of the output signal of the above and reproducing the code signal.

The control command output from the decoder 80 is:
A code for instructing ON / OFF of a power supply, a wiper, a tilting, a panning, a zoom, or the like, or a code for instructing start or stop of transmission of a video signal. These control commands are supplied to the driver of the corresponding device as signals for controlling the corresponding device.

As is clear from the above description, a composite signal obtained by synthesizing a video signal composed of a composite video signal, an audio signal corresponding to the video signal, and an identification code assigned to the television camera, that is, a multiplexed signal is obtained. Is transmitted from each television camera 18 to the corresponding transmitting device via the video signal transmission line 24.

As shown in FIG. 7, each receiving circuit 32 includes an interface 90 for receiving an information signal transmitted by the information transmission line 16 selected by the selecting circuit 30.
The interface 90 transmits the received composite signal to the monitor 9
2 and the video recorder 94.

The monitor 92 is a television receiver for displaying an image corresponding to the video signal transmitted from the transmitting device 12 and reproducing the sound corresponding to the corresponding audio signal.
The video recorder 94 is a video tape recorder that reproducibly records a video signal and an audio signal transmitted from the transmission device 12.

Each receiving circuit 32 has a memory 96 for storing a display signal for checking the television camera connected to the monitor 92 for each television camera, and a decoder for extracting an identification code from the composite signal. That is, based on the identification code extraction circuit 98 and the output signal of the identification code extraction circuit 98, the display signal of the television camera corresponding to the extracted code signal is read out from the memory 96, and is read out from the corresponding selection circuit 30 as the signal. 100 that supplies a display signal to the interface 90 so as to be superimposed on the
0 that drives the selection circuit 30 under the control of 0.

The display signal is a signal for displaying an installation location, a number, an identification code and the like of the corresponding TV camera in characters on the monitor 92, and is superimposed on the video signal of the corresponding TV camera in the interface 90. For this reason, the display signal is recorded on a magnetic tape or the like in the video recorder 94 together with the corresponding video signal and audio signal. The display content for the display signal may be not only characters but also symbols, pictures, bar codes, and the like.

The identification code extraction circuit 98 is similar to the code extraction circuit 76 of the television camera 18 shown in FIG.
A counter for counting the horizontal internal synchronizing signal for each field scan or frame scan of the video signal based on the horizontal internal synchronizing signal Hi and the vertical internal synchronizing signal Vi; In this case, a circuit including a gate circuit for outputting a signal supplied from the video signal transmission line 24 and a code reproducing circuit for reproducing an identification code in the signal output from the gate circuit can be used.

The code reproducing circuit used in the identification code extracting circuit 98 is also a level sensor for reproducing the identification code by sensing the level, envelope, frequency and phase according to the form of the electric signal corresponding to the identification code. , An envelope detector, a frequency detector, a phase detector and the like can be used.

Therefore, when an identification code having the signal waveform shown in FIG. 5A or 5B is used, the identification code extraction circuit 98 uses a synchronization signal separation circuit like the code extraction circuit 76 shown in FIG. 82 and an H synchronization signal counter 84
, A gate circuit 86, and a code reproducing circuit, that is, a level sensor 88.

The identification code reproduced by the identification code extracting circuit 98 is used by the controller 100 to read out a display signal corresponding to the reproduced identification code from the memory 96. Interface 9 from controller 100
The display signal supplied to 0 is superimposed on the video signal at the interface 90 such that characters and the like corresponding to the display signal are displayed on the monitor 92. For this reason, the monitor can know on the screen of the monitor 92 which monitored portion the reproduced image is.

The controller 100 has a display control function for changing a display position of a character or a picture corresponding to a display signal on the monitor 92, selecting whether or not to display the character or the like on the monitor 92, and the like. It also has a function of turning the recorder 94 on and off.

The controller 100 includes a control circuit 22 shown in FIG.
Is transmitted / received via the transmission line 104 to / from the server. The signal supplied from the control circuit 22 to the controller 100 includes transmission line selection information for specifying an information transmission line to be selected, and an external synchronization signal for specifying switching timing.

When the transmission line selection information and the external synchronization signal are supplied to the controller 100, the controller 100 changes the drive command corresponding to the received transmission line selection information when the external synchronization signal is received, that is, when the external synchronization signal is received. Driver 1 in synchronization with the signal
02. Accordingly, the driver 102 drives the selection circuit 30 so as to select the information transmission line 16 corresponding to the drive command, and therefore, an information signal from a transmission device connected to the selected information transmission line is input to the interface 90. .

As a result, the video signal and the audio signal from the television camera specified by the transmission line selection information are reproduced by the monitor 92 and recorded on the video recorder. Monitoring can be performed on the screen 92, and the location of the monitored part being reproduced can be confirmed by characters or the like corresponding to the display signal in the displayed image.

When a character or the like corresponding to the display signal is superimposed on an important part of the image reproduced on the monitor 92, the observer issues a command to stop displaying the character or the like.
Alternatively, by directly inputting a command to change the position of the character or the like on the monitor 92 to the controller 100 or supplying the same from the control circuit 22 shown in FIG. 1, an image corresponding to the video signal can be accurately confirmed. it can.

According to the information signal selecting device 10 according to the present invention, the transmitting device and the receiving device can be arbitrarily combined and connected in a one-to-one manner by a simple device, and one transmitting device can be connected to an arbitrary one device. The transmitting device and the receiving device can be arbitrarily combined and connected, for example, the device can be connected to a plurality of receiving devices.

Further, since the switching timing of the information transmission line in the selection circuit 30 corresponds to the phase of the external synchronization signal supplied to the controller 100 together with the transmission line selection information, that is, coincides with the phase, the selection circuit 30 returns the video signal. The information transmission line is switched during the line period. As a result, the reproduced image corresponding to the video signal during or immediately after the switching of the information transmission line is not disturbed.

When the television camera is synchronized by a horizontal and vertical synchronizing signal, a composite synchronizing signal, or a horizontal and vertical driving signal, a circuit for generating a horizontal and vertical synchronizing signal, a composite synchronizing signal, or a horizontal and vertical driving signal is provided. It can be used instead of the external synchronization signal generation circuit 20 shown in FIG. In this case, the external synchronization signal insertion circuit 36 and the external synchronization signal clipping circuit 38 become unnecessary.

Instead of providing the external synchronizing signal insertion circuit 36 and the external synchronizing signal clipping circuit 38 in the transmitting device 12, the external synchronizing signal P1 may be directly supplied to the level comparison circuit 62 of the television camera 18 shown in FIG. When the television camera does not include the level comparison circuit, a signal corresponding to the pulse signal P3 may be directly supplied to the internal synchronization signal generation circuit 64 of the television camera 18 as an external synchronization signal. Also in the latter case, the external synchronization signal insertion circuit 36 and the external synchronization signal clipping circuit 38 of the transmission device 12 are not required.

The combining circuit 42 of the transmitting circuit 26 modulates a carrier for a video signal with a video signal, modulates a carrier for an audio signal with an audio signal, and outputs a combined signal of both carriers, such as a radio wave for television broadcasting. It can be a circuit. In this case, the receiving circuit 32 separates both carriers,
A circuit for demodulating the video signal and the audio signal;

Further, the synthesizing circuit 42 sets the time axis of the audio signal such that the audio signal corresponding to one vertical scanning period of the video signal has a time corresponding to one or more horizontal scanning periods of the video signal. And a circuit for inserting the compressed audio signal into a vertical blanking period, preferably a vertical blanking period, of the video signal. In this case, the receiving circuit 32 includes a circuit that extracts the audio signal from the video signal and demodulates the time axis of the extracted audio signal.

As the synthesizing circuit 42, other circuits than those described above may be used. The audio signal insertion circuit 70 of the television camera 18 can also be a circuit similar to the synthesis circuit 42 of the transmission circuit 26.

Instead of supplying a control signal for the television camera 18 from a single control circuit to all the transmission devices 12, a control signal is supplied from one control circuit to any number of two or more transmission devices. Alternatively, a control circuit may be provided for each transmission device, and a control signal may be supplied from each control circuit to the corresponding transmission device. Further, the control signal may be transmitted from the reception device to each transmission device using the information transmission line 16. It may be transmitted.

Instead of controlling all the receiving devices by a single control circuit, one control circuit may control two or more arbitrary number of receiving devices, or a control circuit may be provided for each receiving device. The receiving device may be provided and controlled by a corresponding control circuit.

The information signal selection device 110 shown in FIG. 8 is provided with a control circuit 22 whose selection state is adjusted by a master control unit, that is, a main control circuit 112, for each of the reception devices 14. Control is performed by the corresponding control circuit 22.

The main control circuit 112 adjusts the receiving state of the receiving device 14 such as the disagreement of the selection prohibition of the receiving devices 14 and the selection of superimposition by the receiving device 14, and supplies an instruction for adjustment to the predetermined control circuit 22. . The adjustment command is, for example, a code indicating a selectable information transmission line, a non-selectable information transmission line, and the like.

When the transmission line selection information is input by an operator or the like, each control circuit 22 associates the input transmission line selection information with the external synchronization signal P1 supplied from the external synchronization signal generation circuit 20. To the receiving circuit 32 of the receiving device 14. The transmission line selection information and the external synchronization signal are actually supplied to the controller 100 shown in FIG.

Thus, the controller 100 supplies the drive command corresponding to the received transmission line selection information to the driver 102 in synchronization with the external synchronization signal, and the driver 102 selects the information transmission line 16 corresponding to the drive command. Selection circuit 3
0 is driven.

In the information signal selection device 110,
The control circuit 22 may have the function of the controller 100.
Further, the external synchronization signal may be supplied to the control circuit 22 via the main control circuit 112.

The information signal selecting device 120 shown in FIG. 9 transmits a control signal from each receiving device 14 to the transmitting device 12 via the information transmission line 16. Therefore, each transmitting device 12 includes an interface 122 for receiving a control signal, and each receiving device 14 includes a drive circuit 124 for transmitting a control signal.

The controller 100 of each receiving circuit 32 shown in FIG. 7 used in the embodiment shown in FIG.
2 to extract the control signal transmitted therefrom, and output the extracted control signal to the drive circuit 124. Drive circuit 124
Inserts a control signal supplied from the controller 100 into a predetermined information transmission line 16 in response to the controller 100 receiving a control signal transmission instruction from the control circuit 22. However, the drive circuit 124 may insert the control signal only into the information transmission line connected to the transmission device corresponding to the device code in the control signal supplied from the controller 100.

Each interface 122 extracts a control signal transmitted by the information transmission line 16 and supplies the extracted control signal to the control signal generation circuit 50 in FIG.
The control circuit 22 prevents the same television camera 18 from being driven by control signals from a plurality of receiving devices 14 and prevents inconsistent control signals from being supplied to the same television camera.

An information signal selection device 130 shown in FIG.
It has the function of the information signal selection device 110 shown in FIG. 8 and the function of the information signal selection device 120 shown in FIG. For this reason,
The information signal selection device 130 includes a main control circuit 112, a control circuit 22 provided for each reception device 14, and a transmission device 12.
Interface 122 provided for each of the receiving devices 1
And a drive circuit 124 provided for every four. Each of these circuits operates similarly to the corresponding circuits in FIGS.

An information signal selection device 140 shown in FIG.
In the information signal selection device 130 shown in FIG. 11, the control signal is transmitted only via the reception device 14 and the information transmission line 16. In the information signal selection device 140, the main control circuit 112 receives a signal indicating the currently selected information transmission line from each control device 22, and outputs a signal for controlling the transmission device to the information connected to the transmission device 12. The signal is output to the control circuit 22 of the receiving device that has selected the transmission line.

In the above embodiment, the same number of transmitting devices 12 and receiving devices 14 are arranged, but the number of transmitting devices 12 and the number of receiving devices 14 may be different. In the illustrated example, each television camera 18 corresponds to the transmission device 12, but each television camera 18 may correspond to a plurality of transmission devices 12. Further, as an information generating device for generating information to be transmitted, a TV camera 1
Instead of using the video signal generator of FIG. 8, a video signal generator of another device such as a video signal reproducing device may be used.

As described above, the present invention has been described with reference to the above-described embodiments. However, various modifications and applications are possible within the scope of the present invention. For example, the present invention provides only an information signal selecting device used in a monitoring system. Alternatively, the present invention can be applied to other information transmission devices, but these modifications and applications are not excluded from the scope of the present invention.

[0095]

As described above in detail, in the invention according to claim 1 of the present application, each receiving means is connected to a plurality of transmitting means by a plurality of corresponding information transmission lines, and an information signal of the plurality of receiving means is transmitted. The switching timing is synchronized with, for example, a vertical blanking period, preferably a vertical blanking period, by an external synchronization signal. Further, each receiving means is connected to the plurality of transmitting means, and the information signal from which the external synchronization signal has been removed is transmitted. A plurality of information transmission lines to be transmitted and an external synchronization signal are generated, and the external synchronization signal is transmitted using a transmission line dedicated to external signal transmission provided separately from the information transmission line provided between a plurality of transmission and reception. External synchronizing signal generating means for supplying the plurality of transmitting means and the plurality of receiving means, wherein each of the plurality of transmitting means removes an external synchronizing signal from the information signal. The broadcast signal includes a distribution circuit for supplying via the information transmission lines, each of said plurality of receiving means,
A selection circuit for switching between one or more of the information transmission lines and the information transmission lines, wherein switching of the information transmission lines in the selection circuit provided in the receiving means is performed in synchronization with an external synchronization signal in a vertical flyback period And the video signal is added to the information signal, so that the reproduced image by the video signal during and immediately after the switching operation is not disturbed. In addition, since a selection circuit is provided for each receiving means, even if the number of transmitting means and receiving means is large, the transmission means and the receiving means to be connected can be easily connected with a simple device without causing disturbance in the reproduced image. Can be switched. In the invention according to claim 2 of the present application, in addition to the effect of the invention according to claim 1, the level of the external synchronization signal is higher than the white level of the video signal and lower than the black level of the video signal. The device and the receiving device can be operated stably. In the invention according to claims 3 to 6 of the present application, the effect of the above invention is further enjoyed in an information signal selection device that multiplexes a signal for identifying each of the transmitting and receiving means into a video signal. In the invention according to claims 7 to 9 of the present application, the effect of the above invention can be enjoyed also in an information signal selection device for multiplexing an audio signal with a video signal. Claim 1 of the present application
In the invention according to the aspect No. 0, the control signal can be freely exchanged between the transmitting and receiving means, and the information signal selecting device can be smoothly operated. In the invention according to claims 11 to 14 of the present application, since the master control unit is further provided, the selecting operation of the information signal selecting device can be performed extremely smoothly and accurately.

[Brief description of the drawings]

FIG. 1 is a diagram showing a preferred embodiment of an information signal selection device according to the present invention.

FIG. 2 is a diagram showing a waveform of a signal transmitted by the device shown in FIG.

FIG. 3 is a block diagram of an electric circuit showing a preferred embodiment of a transmission device in the device shown in FIG. 1;

FIG. 4 is a block diagram of an electric circuit showing a preferred embodiment of a television camera in the apparatus shown in FIG. 1;

FIG. 5 is a diagram showing a waveform of an identification code signal.

FIG. 6 is a block diagram of an electric circuit showing a preferred embodiment of a code extraction circuit in the television camera shown in FIG. 4;

FIG. 7 is a block diagram of an electric circuit showing a preferred embodiment of a receiving device in the device shown in FIG. 1;

FIG. 8 is a diagram showing another preferred embodiment of the information signal selection device according to the present invention.

FIG. 9 is a diagram showing another preferred embodiment of the information signal selection device according to the present invention.

FIG. 10 is a block diagram of an electric circuit showing a preferred embodiment of a receiving device in the device shown in FIG. 9;

FIG. 11 is a diagram showing another preferred embodiment of the information signal selection device according to the present invention.

FIG. 12 is a diagram showing another preferred embodiment of the information signal selection device according to the present invention.

[Explanation of symbols]

 ... Information signal selection device 12... Transmission device 14... Reception device 16... Information transmission line 18. Synchronization signal generation circuit 22 ... Control circuit 24 ... Video signal transmission line 26 ... Transmission circuit 28 ... Driver 30 ... Selection circuit 32 ... · Receiving circuit 34 · · · · · Pulse shaping timing circuit 36 · · · · · External synchronization signal insertion circuit 38 · · · · · External synchronization signal clipping circuit 40 · · · · · Transmission line 42 · · · · · · Synthesis Circuit 44: Control signal generator 46: Synchronous separation circuit 48: Transmission line 50: Control signal generation circuit 52: Counter 54: .Gate signal generation circuit 56... Gate circuit 58... 60 Reference voltage source 62 Level comparison circuit 64 Internal synchronization signal generation circuit 66 Video signal generation circuit 68 Audio signal generation circuit 70 ······ Audio signal insertion circuit 72 ······ Identification code setting circuit 74 ······ Identification code insertion circuit 76 ····· Code extraction circuit 78 ······ Code comparison circuit 80 ····· Decoder 82 ·············································································· ... Monitor 94 ... Video recorder 96 ... Memory 98 ... Identification code extraction circuit 100 ... Controller 102 ... Driver 110 ... Information signal selection device 112 ... main control circuit 120 ----- information signal selecting apparatus 122 ----- interface 130 ----- information signal selecting apparatus 140 ----- information signal selecting device

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 7/18 H04N 5/268

Claims (14)

(57) [Claims] 1. An information signal selecting apparatus, comprising: a plurality of transmitting means for respectively processing electrical information signals including a video signal; a plurality of receiving means for selectively receiving the video signal; A plurality of information transmission lines connected to a plurality of transmission means for transmitting the information signal from which the external synchronization signal has been removed, and an external synchronization signal generated,
External synchronization signal generating means for supplying it to the plurality of transmitting means and the plurality of receiving means using a transmission line dedicated to external signal transmission provided separately from the information transmission line provided between the plurality of transmission and reception, Wherein each of the plurality of transmitting means has a distribution circuit for supplying the information signal obtained by removing an external synchronization signal from the information signal via the information transmission line, and each of the plurality of receiving means Has one or more information transmission lines and a selection circuit for switching between the information transmission lines, and the switching of the information transmission lines in the selection circuit provided in the receiving means is performed in a vertical return in synchronization with an external synchronization signal. A plurality of video signal generating means corresponding to the transmitting means for supplying a video signal thereto, wherein the plurality of video signals are added to the information signal. Each of the video signal generation means has an internal synchronization signal generation circuit synchronized by the timing of an external synchronization signal sent from the transmission means, and supplies the video signal to a corresponding transmission means, and at least one of the The receiving means has processing means for recording and reproducing a video signal included in the information signal sent from the selection circuit, and further, the external synchronization signal is higher than the highest voltage of the video signal or the lowest of the video signal. A circuit having a level lower than a voltage, wherein each transmitting means inserts an external synchronization signal toward an information transmission line between the transmitting means and the video signal generating means, and the information signal transmitted from each transmitting means to each receiving means. And a circuit for excluding an external synchronization signal from the information signal selection device. 2. The video signal generating means further compares the signal level of the pulse signal with a reference signal having a predetermined voltage level to extract the external synchronizing signal, and outputs the extracted external synchronizing signal to the internal signal. The information signal selection device according to claim 1, further comprising a comparison circuit that supplies the synchronization signal to the synchronization signal generation circuit. 3. The video signal generating means further generates an identification code signal corresponding to the identification code assigned to the video signal generating means, and inserts the identification code signal into the video signal output to the transmitting means. An identification code signal generating circuit, wherein the at least one receiving means further extracts the identification code signal in the signal output from the selection circuit, and outputs a signal corresponding to the extracted identification code signal to the video signal. 3. The information signal selecting apparatus according to claim 1, further comprising an identification code signal processing means for outputting to the processing means. 4. An identification code signal processing means, comprising: a memory for storing data relating to each identification code signal; and a decoder signal for extracting and decoding the identification code signal in a signal output from the selection circuit. The information signal selection device according to claim 3, further comprising: an extraction circuit that generates the data, and a controller that retrieves data related to the decoder signal from the memory and superimposes the retrieved data on the video signal. 5. A control means for generating a control signal including a coded control instruction for controlling said video signal generating means together with an identification code signal corresponding to an identification code assigned to each video signal generating means. The control signal is transmitted to the video signal generating means so as to operate the circuit corresponding to the control signal only when the associated identification code signal corresponds to the identification code signal permitted to the video signal generating means. The information signal selection device according to claim 2, wherein the information signal is supplied. 6. The control signal is inserted into a video signal transmission line connecting the video signal generation means to the transmission means, and the video signal generation means further transmits the control signal from the video signal transmission line. Control signal processing means for supplying the extracted control signal to a circuit corresponding to the extracted control signal when the associated identification code signal corresponds to the identification code permitted to the video signal generation means; The information signal selection device according to claim 5, wherein the information signal selection device includes: 7. Each of the transmitting means further generates a multiplexed signal of a video signal and an audio signal by inserting an audio signal into the video signal, and outputs the multiplexed signal to a plurality of corresponding information transmission lines. The information signal selecting device according to claim 1, further comprising a coupling unit. 8. Each video signal generating means further generates a multiplexed signal of a video signal and an audio signal by inserting an audio signal into the video signal, and supplies the multiplexed signal to the corresponding transmitting means. The information signal selecting device according to claim 1, further comprising a coupling unit. 9. The information signal selecting apparatus according to claim 7, wherein each receiving means further comprises an audio signal recovering means for recovering an audio signal from the multiplexed signal and outputting the recovered signal. 10. Each receiving means further includes a control signal driver for supplying said control signal to said plurality of information transmission lines in a direction opposite to a propagation direction of said video signal, and each transmitting means further comprises: The information signal selection device according to claim 5, further comprising a control signal extractor for extracting the control signal from the information transmission line and supplying the extracted control signal to a corresponding video signal generator. 11. A control means provided for each of said receiving means for supplying a transmission line selection signal designating an information transmission line to be selected to said selection circuit, a selectable information transmission line and a non-selectable information transmission line. 2. The information signal selecting apparatus according to claim 1, further comprising: a master control unit that outputs a code designating the information transmission line to the control unit. 12. The control circuit according to claim 1, further comprising a control code for instructing on / off of each device forming said video signal generating means, said control code being supplied to said video signal generating means via said information transmission line. And a master control unit that outputs a code indicating a selectable information transmission line and a non-selectable information transmission line to the control unit. The information signal selection device according to claim 1. 13. A transmission line selection signal for designating an information transmission line to be selected, and a control code for instructing on / off of each device forming the video signal generating means, the control code comprising: A control means for supplying a control code to be supplied to the video signal generation means to the selection circuit, a control means disposed for each of the reception means, and a code indicating a selectable information transmission line and a non-selectable information transmission line. The information signal selection device according to claim 1, further comprising a master control unit that outputs the information signal to a control unit. 14. The master control unit further comprises:
14. The information signal selecting device according to claim 12, wherein each of the control circuits of the receiving means and each of the video signal generating means connected to the plurality of information transmission lines are controlled.