JP3041033B2 - Video recording system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a security and surveillance video recording system combining a television camera, a VTR, and a sensor.

[Summary of the Invention]

When recording video signals from a surveillance television camera, a VTR is used. However, if the frequency of the video to be recorded is low, continuous recording on a VTR not only wastes the video tape, but also makes the video head useless. There was a problem in terms of the life of the VTR, such as wear of the mechanical part of the tape running system and wear of the video tape. On the other hand, conventionally, there is a method in which the recording timing is detected by a sensor or the like, and only during that time, the VTR is activated from the stop state to the recording state to record.
Since recording cannot be performed for a few seconds required as a start-up time, there is a drawback that a video immediately after the occurrence of a particularly important abnormality cannot be recorded.

According to the present invention, a video delay circuit for a VTR activation time is provided in a preceding stage of the VTR, and when the VTR is activated by a sensor signal input and enters a recording state, a video signal supplied to the VTR is converted to a video signal at the time of the sensor signal input. In this manner, all necessary video signals from the video signal immediately after the occurrence of the abnormality can be recorded on the VTR.

Furthermore, if a video delay circuit longer than the VTR activation time is used, a system capable of recording the video signal before the occurrence of the abnormality can be constructed.

[Conventional technology]

FIG. 4 shows a system diagram of a conventional system in which an abnormality is detected by a sensor signal and the VTR is changed from a stopped state to a recording state and a camera monitoring video signal is recorded. The video signal from the video camera 1 is displayed on the monitor 5 via the VTR 3.
Reference numeral 6 denotes a sensor, and reference numeral 12 denotes a sensor power supply, which supplies an abnormality detection signal from the sensor 6 to the VTR 3, starts the VTR 3 from a stopped state to a recording state, and records a video signal.

FIG. 5 (C) shows the timing of sensor signal input, and tr shown in FIG. 5 (A) shows the activation time from the VTR3 stopped state to the recording state. (D) shows the rising state of VTR3, and the time of the wavy waveform matches tr. (B)
Represents a video signal (screen unit) supplied to the VTR 3, and each numeral is assigned from the time of input of the sensor signal (C).

If VTR3 is subjected to timing of the sensor signal at time-to (C), a video signal that can be actually recorded after time t _1, only the video signal shown in (E) is recorded in the VTR3. That is, of the video signals shown in (B), the video signal in the tr period is not recorded.

[Problems to be solved by the invention]

An important image to be recorded by the monitoring camera is often immediately after the generation of a sensor signal for abnormality detection, and the conventional system described above has a disadvantage that this image cannot be recorded.

An object of the present invention is to record a video immediately after a sensor signal is generated in a VTR in a system for starting and recording a VTR from a stop state to a recording state in response to a sensor signal input.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a
A video delay circuit that delays the video signal by the VTR activation time from when the VTR receiving the recording control signal from the sensor signal changes from the stop state to the recording state until complete recording is possible is provided. After the signal input is interrupted, a controller for transmitting a recording control signal is combined so that the recording is extended by the VTR activation time.

[Action]

As a result, the video signal supplied to the VTR is a video that is earlier than the video currently captured by the video camera by the VTR activation time. That is, at a certain point, the sensor operates and a recording control signal is supplied to the VTR. The VTR starts up from the stop state to the recording state with a start-up time of several seconds. Since the image delay time can be set so that the supplied image signal becomes an image at the time of the sensor operation, the image from the time of the sensor operation can be reliably recorded. In addition, by extending the recording control signal by the video delay time from the time when the sensor operation is completed,
Even in a video recording system in which R is changed from the stopped state to the recording state, it is possible to completely record the video from the time when the sensor operation starts to the time when the sensor operation ends.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.
1 is a television camera, 2 is a video delay memory device, 3 is a VTR, 4 is a video switch, 5 is a monitor, 6 is a sensor, and 7 is a VTR controller. When the VTR 3 is activated from the stop state by the recording control signal 7a and the VTR activation time tr until complete recording is set to 3 seconds, one frame is 1/30.
Since it is seconds, 3 (seconds) ÷ 1/30 (seconds / frame) = 90 (frames), that is, it consists of a frame memory for 90 screens. In the following description, a 90-frame video delay memory device will be described, but the number of the frame memories may be appropriately increased or decreased according to the activation time of the VTR to be combined to configure the system.

FIG. 2 shows a principle diagram of the video delay memory device 2. 8
(M1 to M90) are frame memories, 9 is a write control circuit, 10 is a read control circuit, and 11 is a write / read switching circuit. For example, when a video signal is being written to M1 of the frame memory 8, an operation is performed to read the video signal of M2, and similarly, this is cyclically repeated for the frame memories of M1 to M90, so that the video delay is reduced. Configure a memory device.

The video signal from the television camera 1 is input to the video delay memory device 2 and is transmitted to the VTR 3 with a delay of 3 seconds. FIG. 3B shows a real-time video signal obtained from the television camera 1 in frame units, and FIG. 3D shows the video signal written in the frame memories M1 to M90. The numbers in the frame are those in which the video signal at the sensor operation start time to is set to 1 and the subsequent video signals are assigned numbers continuously for each frame. (E) is a video delay memory device 2
The video signals read from the frame memories M1 to M90 are transmitted to the VTR 3 with a delay of 90 frames (3 seconds). That is, the video signal supplied to VTR3 is
3 seconds ago. Therefore, the sensor 6 detects the abnormality of the subject and sends a recording control signal 7a to the VTR 3 via the VTR controller 7, and the VTR 3 starts recording with a start time tr of 3 seconds. ₁ , the video signal supplied to VTR3 is the video signal three seconds before, that is, when the operation of sensor 6 starts.
Therefore, the video from the time of occurrence of the abnormality can be reliably recorded.

FIG. 3 (F) shows the timing of the recording control signal 7a supplied from the VTR controller 7 to the VTR 3, and the recording control signal of the time obtained by adding the activation time tr of the VTR 3 to the sensor operation time ts. Video signal delayed by the start time tr
Make sure to record. FIG. 3 (H) shows a video signal reliably recorded on the VTR3.

(C) shows the sensor signal input, (G) shows the rising state of VTR3, and the wavy waveform of (G) shows the unstable state at the start time tr of VTR3.

Next, an operation when the number of frame memories of the video delay memory device 2 is reduced will be described. Although one frame of a video signal is composed of 1/30 second, there are many cases where there is no practical problem even if the video signal for monitoring is thinned out at appropriate intervals and recorded. For example, if an image is recorded approximately every 0.1 second, that is, at an interval of 3 frames, the number of frame memories of the image delay memory device 2 is 3 (seconds) ÷ 3/30 (seconds / frame) = 30 (frames). A frame memory for 30 screens is sufficient for practical use.

That is, the video delay memory device 2 sets the activation time t of the VTR 3
During r, the video signal (B) of the television camera 1 is written into the frame memories M1 to M30 as shown in (I) while thinning out every three frames.

Then, at the same time as VTR3 completely starts recording, the video signal is read out sequentially from the frame memory M1 at an interval of 1/30 second, and the past video signal for the VTR activation time tr is transmitted to the VTR3. At the same time as reading the video signal of M1, the real-time video signal from the television camera 1 is written, and this is repeated using the frame memories M1 to M30 as a circulating memory. By performing the video delay operation of
A video signal is supplied to the VTR 3 as shown in FIG.

Even if the number of frame memories is reduced in this way, a sufficient image for monitoring can be recorded in the VTR3 from the start of the sensor operation.

Even if the VTR 3 is used for a long time, the write / read switching operation timing is changed due to different recording intervals, but the same recording can be performed with the same principle and configuration.

〔The invention's effect〕

According to the present invention, in a video recording system in which a head or a mechanical unit, which is a consumable part of a VTR, is normally stopped without operating and a recording is started by a sensor operation signal, the VTR has a longer life. Thus, a complete recording system can be configured without generating a video missing portion corresponding to the startup time.

Even if the number of frame memories is reduced to the practical limit,
It is also possible to configure a recording system having the same function by controlling the memory writing interval.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a block diagram showing one principle of a video delay memory device, FIG. 3 is a timing diagram of video signals and control signals according to the present invention, and FIG. FIG. 4 is a block diagram showing an example of a conventional video recording system, and FIG. 5 is a timing diagram of a conventional video signal and control signal. 1: TV camera, 2: Video delay memory device, 3: VTR, 5: Monitor, 6: Sensor, 7: VTR controller, 8: Frame memory, 9: Write control circuit, 10: Read control circuit, 11: Write・ Read-out switching circuit.

Claims (3)

(57) [Claims] In a video recording system for recording video from a television camera including a video recording device, a television camera for capturing an image of a monitoring target, a video signal from the television camera are input, and the video input signal is used as the video input signal. A video delay circuit that gives a video delay time longer than the activation time of the recording device and outputs the delayed video output signal to the recording device, the recording device that records the delayed video output signal of the video delay circuit, and a sensor that detects the movement of the monitoring target; A recording device control unit that controls the recording device based on an output of the sensor, a selection unit that selects any of an output signal from the recording device and an output signal from the television camera, and a selection unit that is selected by the selection unit. A video recording system comprising a monitor for reproducing a video signal. 2. The video according to claim 1, wherein the number of frames or field memories used in said video delay circuit is the number of frames taken in at predetermined time intervals with respect to the start-up time of said recording device. Recording system. 3. The video recording system according to claim 1, wherein said video delay circuit is built in said recording device.