JPH0737418Y2 - Video switch - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a video switching device used in a surveillance system in which a time-lapse VTR capable of recording for a long time and a plurality of CCTV cameras are combined.

(Prior art and its problems) Since the time-lapse VTR is an intermittent recording system, this VTR
In a CCTV surveillance system that uses, the video switching timing of the video switching device to be combined must be synchronized with the intermittent recording timing. This is because if the switching interval of the video switcher is narrower than the recording interval of the VTR, the video of the camera that must be sequentially recorded in the VTR will be recorded in a missing manner, and conversely the switching interval will be shorter than the recording interval. This is because if it is wide, images from the same camera are recorded many times, which is not efficient.

FIG. 2 is a block diagram of a video switching device used in a conventional surveillance system. The camera 1 operates in external synchronization via the horizontal synchronization buffer 11 and the vertical synchronization buffer 12 according to the horizontal / vertical synchronization signals from the synchronization signal generator 10. A video signal enters the video switching circuit 4 from the connector 2 via the video buffer 3. Reference numeral 14 is an internal clock generation circuit, and a camera switching clock signal generated therein passes through an internal / external cook changeover switch 15 and enters an AND gate 16.

The clock signal is synchronized with the vertical blanking timing pulse obtained from the vertical synchronizing signal via the waveform shaping circuit 13 by the AND gate 16 and becomes a camera switching pulse, which is input to the video switching circuit 4. The video signal is switched at the timing of the camera switching pulse and is output from the video output connector 6 via the buffer 5. The video signal obtained from the video output connector 6 is input to the time lapse VTR 8 and the video monitor 7.

The above is the operation when the internal / external clock selector switch 15 is internal, but when it is external, the time-lapse VTR8
The clock signal for camera switching from is passed through the gate circuit 17 via the clock input terminal 9 and the AND-gate 6 through the internal / external clock switching switch 15 to generate the camera switching pulse as in the internal case. Become.

The problem here is the cycle of the camera switching clock. In the case of internal operation, the adjuster of the internal clock generation circuit 14 adjusts to a period suitable for visual monitoring and monitors, but since the time-lapse VTR performs intermittent recording, the intermittent period and video switching are performed. If the cycles do not match, the recorded images will be lost or duplicated.

Also, in the case of external operation, if a camera switching clock that matches the intermittent recording cycle from the time-lapse VTR is used, the video switching timing is fixed at the intermittent cycle, which is not suitable for visual monitoring. There is a possibility that For example, the intermittent period of time-lapse VTR in 24-hour recording mode is 0 for field recording VTR.
2 seconds, 0.4 seconds for VTR of frame recording system, and 4 seconds or 8 seconds when used in 480 hours recording mode, respectively. If the cycle is short, it cannot be visually confirmed. As the number of cameras connected to the network increases, it takes too much time to complete one round, and efficient monitoring cannot be performed.

(Purpose) The object of the present invention is to solve these drawbacks and to satisfy both the video switching timing of about 0.5 to 3 seconds suitable for visual monitoring and the timing of about 0.1 to 8 seconds for time-lapse VTR. To provide.

In order to achieve the above object, the present invention is provided with a visual image switching circuit and a time-lapse VTR recording image switching circuit,
It is characterized in that each is configured to switch the image at a switching timing suitable for the purpose.

(Embodiment) A block diagram of an embodiment of the video switching device according to the present invention shown in FIG. 1 will be described below.

The camera 1 uses the horizontal and vertical sync signals from the sync signal generator 10 for horizontal sync buffer 11 and vertical sync buffer.
It operates by external synchronization via 12. A video signal is output from the connector 2 via the video buffer 3 to the video switching circuit 4 and
Entered in 20. The video signal switched and output from the video switching circuit 4 passes through the buffer 5 and the video output connector 6
Output to the video monitor 7 for visual monitoring.

The video signal from the video switching circuit 20 is supplied to the time-lapse VTR 8 for video recording via the buffer 21 and the connector 22.

For the visual monitoring video, the clock generated by the internal clock generation circuit 14 and the vertical blanking timing pulse obtained through the waveform shaping circuit 13 are input to the AND gate 18, and become the camera switching pulse, and the video switching circuit 4 Is supplied to switch the video. The internal clock generation circuit 14 is provided with an adjuster that can arbitrarily set the clock cycle, and can be monitored at a switching timing suitable for visual monitoring.

The video for video recording is a camera switching pulse from the time-lapse VTR 8 through the clock input terminal 9, the gate circuit 17, and the AND gate 19 for timing the vertical blanking. Since it can be switched in synchronization with the recording timing of, it is possible to efficiently record the recorded images without missing or overlapping.

(Effects) As described above, the video switching device according to the present invention has a video output for monitoring at a switching timing of 0.5 to 3 seconds, which is suitable for visual observation, and an interval of 0.1 to 8 seconds for highly efficient recording on a time-lapse VTR. Optimal CCT by providing time-lapse VTR video output with switching timing
It became possible to configure a V monitoring system.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a video switcher according to the present invention, and FIG. 2 is a block diagram of a video switcher used in a conventional surveillance system. 1: Camera, 4: Video switching circuit (for visual monitoring), 7: Video monitor, 8: Time-lapse VTR, 10: Synchronous signal generation circuit, 14: Internal clock generation circuit, 15: Internal-external clock switch, 17: Gate circuit (for external clock), 20: video switching circuit (for video recording).

Claims (1)

[Scope of utility model registration request] 1. A video switching device having a plurality of video signal inputs, switching and sending the video signal inputs to supply to a monitor for monitoring and a time lapse VTR, the video switching signal generator having a video switching signal generator. It has first and second video switching circuits for switching the video signals based on the first and second video switching pulse signals respectively supplied from the switching signal generator and the time-lapse VTR, and the first and second video switching circuits are provided. A video switching device characterized in that the outputs of the video switching circuit 2 are supplied to the above-mentioned monitor for monitoring and the time-lapse VTR, respectively.