JPH0937141A - Video processing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide in-phase video signals from mutually separately positioned plural video cameras. SOLUTION: A video camera driving device 22 respectively controls synchronizing control pulse signals PH1 -PH4 to be applied to the respective video cameras for generating the other video signals so that the phase of the other video signal can be matched with one of plural video signals V1 -V4 inputted from plural video cameras 1-4. Thus, the deviation of phases among the respective video signals caused by the difference in the lengths of signal cables to the respective video cameras is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video processing system for synchronously processing video signals obtained from a plurality of video cameras installed at different positions apart from each other.
The present invention relates to phase synchronization control of each video signal.

[0002]

2. Description of the Related Art A video processing system, such as a surveillance system, which processes video signals coming from a plurality of video cameras installed at positions distant from each other, uses a multi-channel video signal coming from each video camera. There is a demand for confirmation on one monitor, and a system has been proposed in which video signals of a plurality of channels are switched by a device such as a switcher and images of a plurality of channels are simultaneously displayed by a four-division adapter. In these systems, a video camera driving device synchronizes the respective channels so that a switching image is not disturbed when the channels are switched by a device such as a switcher. Specifically, in order to synchronize the plurality of connected video cameras with each other, the video camera driving device is configured to apply the synchronization pulse to the video cameras of all channels at the same timing.

[0003]

However, if there is a difference in the distance to the video camera of each channel connected to the video camera driving device between the channels, synchronization of the same timing is always applied to all the channels. When a pulse is output, a phase shift occurs between channels in the video signal of each channel output from each video camera due to the difference in delay time in the cable between the video camera driving device and the video camera.

Generally, a phase difference of several microseconds occurs when there is a difference of several hundred meters in the length of the cable. This phase difference has no practical problem when simply switching channels at intervals of a few seconds with a device such as a switcher, but it does not affect the input video signal such as a frame switcher for synchronization control or a 4-division adapter. In the case of a system configuration in which image information is read in and read out from the memory by synchronous control, the phase difference of several microseconds between the channels becomes the phase shift of the image information in the horizontal direction as it is.

That is, as shown in FIG. 2, four video cameras 1 to 4 installed at positions distant from each other are connected to a video camera driving device 9 by signal cables 5 to 8, and each of the video cameras 1 to 4 is connected. When the video signals V _{1 to} V ₄ of 4 channels corresponding to are output, a phase shift occurs between the video signals. For example, the video camera 2 is located far from the other video cameras 1, 3, 4, and the signal cable 6 to and from the video camera driving device 9 is the other cable 5, 5.
If it is longer than 7 and 8, video camera driving device 9
The phase of the video signal V ₂ coming in to another video signal V ₁ ,
It is later than V ₃ and V ₄ . When the image information of the plurality of video signals V _{1 to} V ₄ having the phase difference is loaded into the memory at the same timing, in the worst case, the blanking portion of the video signal may be included in the loaded data. There is a loss of image information.

It is an object of the present invention to enable video signals coming from a plurality of video cameras located apart from each other to be obtained in phase.

Another object of the present invention is to provide an image processing system in which video signals transmitted from a plurality of video cameras located apart from each other are subjected to memory control for synchronous control by a frame switcher or a four-division adapter. The object is to prevent the phase shift of the video signal due to the difference in the signal delay amount due to the difference in the signal cable length to the camera and to accurately capture the image information.

Still another object of the present invention is a video processing system in which video signals transmitted from a plurality of video cameras located apart from each other are synchronously controlled by a frame switcher, a 4-division adapter or the like and displayed on one monitor. In, prevent the phase shift of the video signal due to the difference in the signal delay amount due to the difference in the signal cable length to each video camera,
It is to realize stable image display.

[0009]

One feature of the invention is:
In a video processing system that takes in video signals from a plurality of video cameras located at mutually distant locations and processes them synchronously, a sync signal of a video signal coming from one video camera comes from another video camera. The video camera drive means is provided for generating a sync control signal for controlling the other video camera so that the phases of the sync signals of the video signals coincide with each other.

Another feature of the present invention is a video processing provided with a plurality of video cameras installed at mutually distant locations, and a monitoring center for capturing a video signal from each video camera via a signal cable and synchronously processing it. In the system,
A sync control signal for controlling the video signal coming from one video camera so that the phase of the sync signal of the video signal coming from another video camera matches the phase of the sync signal of the video signal coming from another video camera. Is provided with a video camera driving means for generating.

More specifically, the video camera driving means generates a selecting means for selecting one of a plurality of incoming video signals as a reference video signal and a synchronization control signal to be given to the plurality of video cameras. And a phase synchronization control pulse generating means corresponding to each video camera, wherein each phase synchronization control pulse generating means is a video signal in which the synchronization signal of the video signal coming from the corresponding video camera is selected by the selecting means. The synchronization control signal is generated so that it has the same phase as the synchronization signal.

Further, the video processing system comprises an image processing means for synchronously processing a plurality of video signals, and the image processing means comprises a monitor for displaying the plurality of video signals. And

[0013]

The video camera driving means generates the other video signal so as to match the phase of the other video signal with one of the plurality of video signals coming from the plurality of video cameras. To control.

Therefore, a plurality of incoming video signals come in the same phase regardless of the length of the signal cable to the video camera, which facilitates image processing.

[0015]

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

FIG. 1 is a block diagram of a monitoring system which is an embodiment of the image processing system according to the present invention. A plurality of video cameras 1 to 4 which are installed apart from each other
Monitoring center 2 via cables 5-8, respectively.
1 is connected to the video camera driving device 22. The video camera driving device 22 has synchronization control pulse signals PH _{1 to} P ₁ for performing phase synchronization control on each of the video cameras 1 to 4.
Phase synchronization control pulse generating means 23 to 26 for generating H ₄
And a reference channel selection means 27 for selecting one of _four video signals V _{1 to} V ₄ coming from each of the video cameras 1 to 4 as a reference video signal V _X , and the reference channel selection means 27. The reference synchronizing signal of the reference video signal V _X of the channel selected in step 1 is extracted, the reference synchronizing pulse signal PV _X having the same phase as the horizontal synchronizing signal is generated, and the reference is given to each of the phase synchronizing control pulse generating means 23 to 26. A sync pulse generation means 28 and a camera power supply means 29 for supplying power to each of the video cameras 1 to 4 are provided. Reference numeral 31 is an image processing means installed in the monitoring center 21, which takes in the incoming video signals V _{1 to} V ₄ and performs image processing for synchronous control by using a frame switcher, a 4-division adapter, or the like. Display on one monitor.

Each of the video cameras 1 to 4 has a video signal V in a phase synchronized with the sync control pulse signals PH _{1 to} PH ₄ given from the phase sync control pulse generating means 23 to 26 via the signal cables 5 to 8. _{1 to} V ₄ are generated.

The phase synchronization control pulse generating means 23-2
6 is the synchronization control pulse signal PH generated by each
_A phase control pulse generating circuit capable of independently changing the generated phases of _{1 to} PH ₄ , a horizontal synchronizing signal of video signals V _{1 to} V ₄ coming from each of the video cameras 1 to ₄ , and the reference pulse signal PV _X. Generation of the synchronous control pulse signals PH _{1 to} PH ₄ so as to eliminate the phase difference between the phase comparison circuit for detecting the phase difference and the phase control pulse generation circuit based on the comparison result in the phase comparison circuit. A phase control circuit that changes the phase is provided.

The operation of this monitoring system will be described. The reference channel selection means 27 inputs the video signals V _{1 to} V ₄ coming from the respective connected video cameras 1 to 4, selects one reference channel from the video signals V _{1 to} V ₄ , and selects the reference video signal from the selected channel. The signal V _X is given to the reference pulse generating means 10. Here, the method of selecting the reference channel by the reference channel selection means 27 is, for example, video cameras 1 to 4.
Is connected, the reference channel is selected to the video camera 1, and when the video cameras 2 to 4 are connected, the reference channel is selected to the video camera 2, and the video cameras 3 and 4 are connected. If so, the reference channel is selected as the video camera 3, and the reference channel is switched in the order of the video cameras 1, 2, 3, and 4. Therefore, in this embodiment, the video camera 1 is selected as the reference channel. However, what video camera system is selected as the reference channel is not particularly limited.

The reference pulse generation means 28 has a reference video signal V _X (=) output from the reference channel selection means 27.
Giving generates a reference pulse signal PV _X of the horizontal synchronizing signal and the same phase of the reference video signal V _X in the phase sync control pulse generating means 23 to 26 on the basis of V _1). In this case, the phase-locked control pulse generating means 23 of the reference channel which is the basis of the reference pulse signal PV _X is the reference pulse signal P
Ignoring V _X , a sync control pulse signal PH ₁ is generated in a free run and sent to the video camera 1. Then, each of the other phase synchronization control pulse generating means 24 to 26 has a phase in which the horizontal synchronization signals of the video signals V _{2 to} V ₄ coming from the respective video cameras 2 to ₄ coincide with the reference pulse signal PV _X. Therefore, the generation phases of the respective synchronous control pulse signals PH _{2 to} PH 4 given to the respective video cameras 2 to ₄ are changed. That is, each of the phase synchronization control pulse generating means 24 to 26 outputs from the other video cameras 2 to 4 to the phase of the video signal V ₁ output from the video camera 1 of the reference channel and entering the video camera driving device 22. The video camera driving device 22
So that the phases of the video signals V _{2 to} V ₄ coming in
Each synchronous control pulse signal P for each video camera 2-4
The generation phase of H _{2 to} PH ₄ is controlled.

Therefore, there is a difference in the length of the signal cable connecting between the video camera driving device 22 and each of the video cameras 1 to 4, and the delay amount of the signal coming into the video camera driving device 22 is different. Also, the video camera driving device 2
2 is a plurality of video signals V having the same phase between channels.
_{1 to} V ₄ can be obtained. As a result, the image processing means 31 having a device for synchronously controlling memory such as a frame switcher for synchronous control and a 4-division adapter can take in a plurality of video signals V _{1 to} V ₄ in an easily processable form. Therefore, stable image processing becomes possible.

[0022]

According to the present invention, the synchronizing control signal for the video camera generating the other video signal is controlled so that the phase of the other video signal is matched with one of the plurality of video signals coming from the plurality of video cameras. Therefore, a plurality of incoming video signals come in the same phase regardless of the length of the signal cable to the video camera, which facilitates image processing.

When these plural video signals are displayed on one monitor, stable display is possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a monitoring system according to the present invention.

FIG. 2 is a circuit block and a video signal waveform diagram for explaining a phase difference of a video signal between a plurality of channels due to a difference in signal cable length to a video camera.

[Explanation of symbols]

1-4: video camera, 5-8 ... signal cable, 21 ...
Surveillance center, 22 ... Video camera drive device, 23-2
6 ... Phase synchronization control pulse generating means, 27 ... Reference channel selecting means, 28 ... Reference pulse generating means, 31 ... Image processing means.

Claims (8)

[Claims] 1. An image processing system for capturing video signals from a plurality of video cameras located at mutually distant locations and processing the video signals synchronously, wherein a video signal coming from one video camera is synchronized with another video signal. An image processing system comprising video camera driving means for generating a sync control signal for controlling the other video camera so that the phases of the sync signals of the video signals coming from the cameras coincide with each other. 2. The video camera driving means according to claim 1, wherein the video camera driving means generates a selecting means for selecting one of a plurality of incoming video signals as a reference video signal, and a synchronization control signal to be given to the plurality of video cameras. Phase synchronization control pulse generation means corresponding to each video camera, each phase synchronization control pulse generation means, the synchronization signal of the video signal coming from the corresponding video camera of the video signal selected by the selection means A video processing system, wherein the synchronization control signal is generated so as to have the same phase as the synchronization signal. 3. A video processing system according to claim 1, further comprising image processing means for synchronously processing a plurality of video signals. 4. The image processing means according to claim 3,
An image processing system comprising one monitor for displaying the plurality of image signals. 5. A video processing system comprising a plurality of video cameras installed at mutually distant locations and a monitoring center for synchronously processing video signals from each video camera via a signal cable, wherein the monitoring center Generates a sync control signal for controlling another video camera so that the sync signal of the video signal coming from one video camera matches the phase of the sync signal of the video signal coming from another video camera. An image processing system comprising a video camera driving means. 6. The video camera driving means according to claim 5, wherein the video camera driving means generates a selecting means for selecting one of a plurality of incoming video signals as a reference video signal, and a synchronization control signal to be given to the plurality of video cameras. Phase synchronization control pulse generation means corresponding to each video camera, each phase synchronization control pulse generation means, the synchronization signal of the video signal coming from the corresponding video camera of the video signal selected by the selection means A video processing system, wherein the synchronization control signal is generated so as to have the same phase as the synchronization signal. 7. The video processing system according to claim 5, wherein the surveillance center further comprises image processing means for synchronously processing a plurality of video signals coming from each video camera. . 8. The image processing means according to claim 7,
An image processing system comprising one monitor for displaying the plurality of image signals.