JPS60163A - Synchronizing controller of plural video image signal sources - Google Patents

Abstract

PURPOSE:To prevent disturbance of synchronism attended with changeover by changing video image signals from each of plural video image signal sources being independent including a synchronizing signal and extracting selectively the signals. CONSTITUTION:In the state where a video image signal S1 obtained from a television camera 1 is extracted by a changeover circuit 4 and led out of an output terminal 5, a television camera 2 generating a video image signal S2 not extracted by the circuit 4 is synchronized with the camera 1. A vertical synchronizing signal V2 in the signal S2 is made synchronized with a vertical synchronizing signal V1 in the signal S1. Thus, the circuit 4 is changed over together with changeover circuits 6 and 13 so as to connect a moving contact 4c of the circuit 4 to a contact 4b. Even if the state is changed over into a state that the signal S2 obtained from the camera 2 is extracted by the circuit 4 and led out to the terminal 5, the disturbance of the vertical synchronism attended with the changeover is not caused in the video image signal obtained from the terminal 5.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This light is capable of switching all video signals from each of a plurality of video signal sources and selectively extracting them, as well as controlling the synchronization state of the video signal sources from which each video signal is obtained. The present invention relates to a synchronization control device for a plurality of video signal sources.

Background technology and its problems The popular television camera used for home use is
Usually, it is an internal synchronization type that does not require an expensive external synchronization device and has a built-in internal synchronization signal generator. If such an internally synchronized television camera is used alone, is there any particular problem with the synchronization controller? However, if multiple television cameras are in operation and the video signals generated by each are switched and selectively extracted, the individual television cameras may not be synchronized with each other. Since the video signal is not
Synchronization disturbance will occur when switching video signals. Then, the extracted video signal is, for example,
When the image is supplied to a receiver and displayed, there is a disadvantage that the displayed image becomes unsightly due to synchronization disturbances at the time of switching the video signal.

Furthermore, such inconvenience occurs not only when video signals from multiple internally synchronized television cameras are switched and selectively taken out, but also when video signals from internally synchronized television cameras and video signals from internally synchronized television cameras are selectively extracted. This also occurs when video signals obtained from a tape recorder are switched and used selectively, and in the end, video signals from multiple video signal sources that generate video signals each having an independent synchronization signal are generated. will be involved when each of these is switched and selectively taken out.

Purpose of the Invention In view of the above, the present invention is designed to selectively extract video signals from each of a plurality of video signal sources that generate video signals each having an independent synchronization signal, and to It is an object of the present invention to provide a synchronization control device for a plurality of video signal sources, which prevents synchronization disturbance caused by switching in output video signals.

Summary of the Invention A synchronization control device for a plurality of video signal sources according to the present invention includes a switching circuit unit that switches and selectively extracts video signals obtained from each of the plurality of video signal sources, and the above-mentioned signal that is extracted by the switching circuit unit. phase comparison of a first synchronization signal included in one of the plurality of video signals and a first synchronization signal included in another video signal that is not extracted by the switching circuit section among the plurality of video signals described above; and a video signal source from which the above-mentioned other video signals are obtained based on the output of the comparison part, so that the first synchronization signal is synchronized with the first synchronization signal. and a control circuit section. With this configuration, when switching video signals, both video signals related to the switching can be synchronized with each other, and as a result, the video signal sound extracted by the switching circuit section and the synchronization disturbance caused by switching can be synchronized. It can be made such that it does not occur.

Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a synchronization control device for a plurality of video signal sources according to the present invention together with λ video signal sources. In FIG. 1, internally synchronized television cameras 0 and 2 each having a built-in internal synchronizing signal generator configured using, for example, a crystal oscillator are used as video signal sources. These television cameras/and cameras are connected to a synchronization control device 3 according to the present invention. Synchronous control device 3
is provided with a switching circuit G and B which are interlocked with each other, and the output terminal of the television camera/ is connected to the switching contact G of the switching circuit G and the switching contact XB of the switching circuit section,
The output end of the television camera is connected to the switching contact db of the switching circuit and the switching contact ota of the switching circuit. And the movable contact of the switching circuit. is connected to the output terminal +3 and also to the input terminal of the synchronous separation circuit 9.

On the other hand, the movable contact Bc of the switching circuit section is connected to the input end of the synchronous separation circuit 7. The output terminals of the synchronization separation circuits 7 and wo are respectively connected to the Ω input terminals of the comparison circuit g, and the output terminal of the comparison circuit g is connected to one end of the switch IO. The other end of the switch IO is connected to the input end of the memory circuit section //, which includes a memory section, a write circuit, a read circuit, and gold, and an output end of the memory circuit section // is connected to the memory circuit section //. / is connected to the input terminal of a modulation circuit 12 which immediately generates a control signal. The output end of the modulation circuit 12 is connected to the control end of the switch 10 via the mono-staple multivibrator 17, and is also connected to the movable contact /3c of the switching circuit /3 which is interlocked with the switching circuit G and B. .

In addition, the power terminal /B is connected to the power terminal /X provided on the television camera / via chopper /9'C, and the chopper 15 is connected to the power terminal / connected via. The switching contact /3a of the switching circuit /3 is connected to the control terminal of the chopper /1, and the switching contact /3b of the switching circuit /3 is connected to the control terminal of the chopper ζ-75.

In the configuration as described above, the switching circuit switches the video signals Sl and S2 obtained from the television cameras I and Y and selectively takes them out, and outputs them to the output terminal +.
Video signals derived from the switching circuit S/ and 8.2 obtained from the switching circuit and the television camera / and - which are derived from the switching circuit and linked with the switching circuit and which are not extracted from the switching circuit. is taken out. As shown in FIG. 1, the movable contacts of the switching circuit. is connected to the switching contact B, and is also connected to the movable contact B of the switching circuit B. is connected to switching contact B, switching port #! A video signal S/ is taken out from the switching circuit B, and a video signal S2 is taken out from the switching circuit B. This state will be described below.

Television camera that can be removed by switching circuit/
The video signal S/ from the video signal S/ is led to the output terminal S and is also supplied to the sync separation circuit 9, where the vertical synchronization signal 2/ from the video signal S/ is taken out.

On the other hand, the video signal S2 from the television camera taken out by the switching circuit B is supplied to the synchronization separation circuit 7, and the vertical synchronization signals V, + in the video signal s2 are taken out by the synchronization separation circuit 7. Both vertical synchronization signals v and ■2
are supplied to the comparator g, where the phases are compared.

The comparison circuit g detects the entire phase difference between the vertical synchronizing signals V/ and V-, and generates a DC voltage whose level changes in accordance with the detected phase difference as a comparison output. This comparison output is supplied to the memory circuit section // through the switch 10''f when the switch /θ is in the closed state.The memory circuit section // sequentially stores the comparison output from the comparison circuit g. The comparison output read from the storage circuit section // is supplied to the modulation circuit 2.The modulation circuit 7.2 has a period T'lr as shown in FIG. , a rectangular wave signal Sa'(r
and furthermore, within the time width of the rectangular wave signal Sa,
A pulse signal Sbt of a constant frequency and constant amplitude as shown in FIG. 1B is generated. In this case, the period T is set to, for example, 0.3 to /second, and the time width of the rectangular wave f signal Sa is maximum, that is, when the mutual phase difference between the vertical synchronization signal V/ and V2 is maximum. Therefore, even when the comparison output obtained from the memory circuit section // takes the maximum voltage level, it is set to be less than one of the period T. Further, the frequency of the λ pulse signal sb is, for example, about 100H2.

The pulse signal sb generated in the modulation circuit /U is supplied as a chopping control signal to the chopper /G or / left control terminal via the switching circuit /3''f. A pulse signal is applied to the control terminal of the television camera connected to the television camera/or S, which is interlocked with the video signal S/ and S2, whichever is not taken out by the switching circuit. Therefore, in this case, the movable contact /3c of the switching circuit /3 is connected to the switching contact /3b, and the pulse signal Sb is supplied to the control terminal of the chopper /,t. supplied to

As a result, the chopper/left is controlled so that it is on during the period when the pulse signal sb is at the low level V L fc, and is off during the period when the pulse signal sb is at the high level Vn'a. In this way, the chopper 13 has the memory circuit section //
The chopping operation is performed for a period proportional to the voltage level of the comparison output from the television.
Power source B is intermittently supplied from power source terminal /4 to the camera controller.

For this reason, the power supply to the internal sync signal generator built into the television camera λ is periodically cut off during the chopping operation period of -15. The generated vertical synchronization signal, i.e.
The phase of the vertical synchronization signal V,2 in the video signal S2 changes,
At the end of the chopping operation period of <−15, the phase is delayed compared to before the start of this chopping operation period. Note that at this time, the chopper/g remains on.

It is also obtained from modulation circuit/2. <Rus signal] is also supplied to the U monostable multivibrator/7. For example, the monostable multivibrator/7 has a time constant corresponding to the - time period of the period T mentioned above. Therefore, as shown in FIG. An output signal SC is generated which rises to VH, maintains the high level VH'' for a period of time, and then falls to the low level VL'. This output signal S is supplied to the control end of the switch 10, and /θ is the output signal sc at low level VL/
When the voltage reaches t, the voltage is turned on, and when the voltage reaches the high level VH', the voltage is turned off.

Therefore, if the switch /θ is used, the modulation circuit /2 is connected to the pulse signal S
During the period when "bt" is occurring, that is, during the period when the chopper/S is performing chopping operation, it is in the off state, and during this period, the comparison output from the comparator circuit is memorized. During this period, the comparison output that was supplied from the memory circuit unit /l to the memory circuit unit l/ and written to the memory unit immediately before the switch IO was turned off is supplied to the memory circuit unit /l. is continuously read out from the storage section and supplied to the modulation circuit/2.By doing this, during the chopping operation period of the chopper/s, the television camera system The vertical synchronization signal obtained from
This prevents the operation of modulation circuit/2 from being disrupted.

As mentioned above, the chotsuhar/
The left chopping operation is performed, and accordingly, the phase of the vertical synchronization signal V,2 in the video signal S2 obtained from the television camera λ is delayed. Then, such operation is sequentially repeated every cycle T, and the vertical synchronizing signal V2
is changed to match the phase of the vertical synchronizing signal V/ in the video signal Sl obtained from the television camera/. In this process, the modulation circuit/,
The period in which pulse signal Sb2 is fully generated, that is, the length of the chopping operation period of chopper tS, is proportional to the voltage level of the comparison output from the comparison circuit, and therefore Since the phase of the vertical synchronizing signal V2 corresponds to the mutual phase difference between the vertical synchronizing signal V
When the phase of the vertical synchronizing signal V/ matches the phase of the vertical synchronizing signal V/, the modulating circuit 7.2 stops generating the pulse signal Sb at all9.
The chopper/S chopping operation is no longer performed.

After that, if a mutual phase difference occurs between the vertical synchronizing signals V/ and Vλ, the above-described operation is performed again to eliminate the mutual phase difference between the vertical synchronizing signals vl and Vj. Ru.

In this way, the video signal S/ obtained from the television camera l is taken out by the switching circuit and output terminal +
5, the video signal 8.2'! is not extracted by the switching circuit. It is assumed that synchronization is established with respect to the television camera / of the television camera that generates r, and the vertical synchronization signal V2 in the video signal S2 is synchronized with the vertical synchronization signal V / in the video signal Sl. Therefore, from this state, the switching circuit G is switched together with the switching circuits B and 13, and the movable contact qc of the switching circuit D is connected to the switching contact <zb, and the image obtained from the television cameras is Even when the signal S is switched to a state where it is taken out by the switching circuit and led to the output terminal +5, vertical synchronization disturbance accompanying the switching does not occur in the video signal obtained from the output terminal +5.

In the state where the video signal S2 obtained from the television camera is taken out by the switching circuit G and is led out to the output terminal +5, the movable contact B of the switching circuit B is connected. is connected to the switching contact B, and the television is connected by the switching circuit B.
The video signal S/ obtained from the camera/ is taken out, and the vertical synchronization signal V/ in the video signal Si and the vertical synchronization signal v2 in the video signal SJ are taken out from the synchronization separation circuits 7 and 9, respectively, and compared. It is supplied to circuit g. - Also, the movable contact /3c of the switching circuit 13 is connected to the switching contact /3a so that the output of the modulation circuit /2 is supplied to the control terminal of the chopper /l connected to the television camera l. It will be done. Even in this state, if there is a mutual phase difference between the vertical synchronizing signals Vl and v2, the same operation as described above is performed, and the chopper/4 chopping operation is performed. , the power supply from the power terminal/B to the internal synchronization signal generator built in the television camera is periodically cut off, so that the phase of the vertical synchronization signal V/ matches the phase of the vertical synchronization signal V2. controlled.

In this way, in a state where the video signal S2 obtained from the television camera unit is taken out by the switching circuit and led out from the output terminal S, the video signal S7'ff that is not taken out by the switching circuit is: Synchronization is established between the generated television camera/ and the vertical synchronization signal V/ in the video signal Sl to be synchronized with the vertical synchronization signal V2 in the video signals S and 2. Therefore, from this state, switching circuit G is switched together with switching circuits B and /3, and the movable contact G of switching circuit G is switched. is connected to the switching contact lIa, and the video signal S/ obtained from the television camera/ is taken out by the switching circuit and output to the output terminal S. Vertical synchronization disturbances caused by switching do not occur in the video signal obtained from the edge.

In the above example, the phase control of the vertical synchronization signal generated by the internal synchronization signal generator built into the television camera is performed by periodically cutting off the power supply. According to such control, television
There is an advantage that the purpose can be achieved without requiring any special structural changes to the camera/co. however,
It goes without saying that the phase control of the vertical synchronization signal is not limited to being performed by periodically cutting off the power supply, but may be performed by other means. Further, it is also possible to perform synchronization control not only for vertical synchronization signals but also for other synchronization signals such as horizontal synchronization signals.

Further, in the above example, two television cameras are used as video signal sources, but the synchronization control device according to the present invention can Television as a signal source
It can be applied not only to cameras but also when video tape recorders, etc. are used, and in such cases,
Appropriate measures are taken to control the phase of the synchronization signal in the video signal obtained from each video signal source.

Effects of the Invention As is clear from the above explanation, the synchronization control device for multiple video signal sources according to the present invention allows video signals to be controlled independently of each other, such as in multiple internally synchronized television cameras. The video signal sound from each of the plurality of video signal sources that generates all the signals can be selectively extracted by switching appropriately, and moreover, when taking out the video signals, all the video signals that are being output can be extracted from the video signals that are being generated. Since all video signal sources that generate other video signals that have not been extracted can be reliably synchronized with the video signal source, the video signal that has been extracted can be transferred from the video signal from one video signal source to the other video signal source. It is possible to avoid synchronization disturbance when switching from the video signal source to the video signal. And synchronization disturbance during such switching? It is possible to selectively extract video signals from a plurality of video signal sources without having to make any additional structural changes to each video signal source, which is extremely convenient.

[Brief explanation of drawings]

FIG. 1 is a block connection diagram showing an example of a synchronization control device for a plurality of video signal sources according to the present invention with two video signal sources, and FIG. 1A, B, and C are explanations of the operation of the example shown in FIG. FIG. In the figure, l and c are television cameras, g, o and 13 are switching circuits, respectively, and 7 and w are synchronization separation circuits, respectively.
g is a comparison circuit, /θ is a switch, // is a memory circuit, /
2 is a modulation circuit, /ll and /left are respectively choppers, and /B is a power supply terminal.

Claims (1)

[Claims] a switching circuit unit that switches all of the video signals obtained from each of the plurality of video signal sources and selectively extracts the video signals; and a first video signal included in one of the plurality of video signals extracted by the switching circuit unit. and a first synchronizing signal included in another video signal that is not outputted by the switching circuit unit among the plurality of video signals, and an output of the comparing unit. First, the video signal source from which the other video signal is obtained is configured to include a control circuit unit that controls the video signal source so that the second synchronization signal is synchronized with the first synchronization signal. Synchronous control device for multiple video signal sources.