JPH069389B2 - Time-lapse VTR - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention provides a time lapse V suitable for crime prevention and surveillance.
Related to TR (Video Tape Recorder).

[Conventional technology]

2. Description of the Related Art Conventionally, as a video tape recorder used for crime prevention and surveillance, a VTR capable of recording for a long time by intermittently extracting a video signal for every one field (or frame) every plural fields (or frames), that is, , A time-lapse VTR is known.

For example, in the time-lapse VTR disclosed in Japanese Patent Laid-Open No. 58-62985, a video signal of one field extracted for each of a plurality of fields (hereinafter described as a unit of field) is recorded (hereinafter, this is time-lapse. When recording the video signal, the magnetic tape is run at the same speed as when recording the video signal continuously (hereinafter referred to as normal recording), and the magnetic tape is stopped at other times to stop the magnetic field. The inclination angle and track pitch of the tracks formed on the tape are set to be the same as in the case of normal recording. As a result, when the magnetic tape is run at the same speed as in normal recording and played back, the rotary magnetic head plays back and scans each track on the magnetic tape as it is, and a long-time phenomenon appears to be time-compressed. The image will be obtained in good quality without noise bars.

If you want to monitor multiple places such as sales floors at the same time,
It is very convenient to use such a time-lapse VTR. That is, in such a case, a video camera may be installed at each place to be monitored, outputs of these video cameras may be alternately switched by a switcher, and the output of the switcher may be recorded by a time-lapse VTR.

[Problems to be solved by the invention]

By the way, when recording is performed by switching the outputs of a plurality of video cameras in this way, tracks on which outputs of different video cameras are recorded are alternately arranged on the magnetic tape. For example, as shown in FIG. 4, when two video cameras 7 and 8 are used, if a video signal of one field is recorded on one track on the magnetic tape 9 once, When the output of the video camera 7 is recorded in C1-A, the next track C2-A
The output of the video camera 8 to the next track C1.
-The output of the video camera 7 is recorded in -B, and the output of the video camera 7 is recorded on every other track.
The output of the video camera 8 is recorded on every other other track.

Therefore, when the magnetic tape 9 is reproduced, the outputs of the two video cameras 7 and 8 are alternately reproduced for each field, and there is a problem that the flow of the reproduction screen lacks uniformity and is difficult to see.

An object of the present invention is to solve such a problem and provide a time-lapse VTR capable of reproducing only an output of a desired video camera from a magnetic tape in which outputs of a plurality of video cameras are alternately recorded. It is in.

[Means for solving problems]

In order to achieve the above object, the present invention counts tracks on the magnetic tape when reproducing the magnetic tape, and a reproduction signal from the magnetic tape is counted every time the counted value becomes equal to the number of video cameras. Is extracted one field or one frame at a time.

[Action]

When even one track in which the output of the desired video camera on the magnetic tape is recorded is detected, the reproduction signals of every number of tracks equal to the number of video cameras are extracted based on this track. These tracks are recorded from the output of the desired video camera, and therefore only the output of the desired video camera can be reproduced.

As a method of detecting the track in which the output of the desired video camera is recorded, for example, there is a method of still reproducing some tracks.

〔Example〕

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

FIG. 1 is a block diagram showing a basic configuration of a time-lapse VTR according to the present invention, in which 1 is a video reproducing circuit, 2 is a switch, and 3 is a control circuit.

In the figure, a video signal reproduced from a magnetic tape (not shown) is supplied to a switch 2 after being subjected to predetermined processing in a video reproducing circuit 1.

On the other hand, on the magnetic tape, a control pulse CTL is recorded for each track, and this is reproduced together with a video signal. The control pulse CTL is supplied to the control circuit 3. The control circuit 3 counts the control pulse CTL and compares the count value with a preset numerical value. This set value is equal to the number of video cameras used for recording, and when the count value matches this set value, the control circuit 3 synchronizes with the control pulse CTL in phase and has a width of one field (or one frame period). The pulse S is output and the counting means for the control pulse CTL is reset. Therefore, the control circuit 3 controls the control pulse CT.
The pulse S is output every time the count value of L becomes equal to the set value. This pulse S is supplied to the switch 2.

The switch 2 is normally closed to the P side, but when the pulse S is supplied, it is switched to the pulse period Q side. Therefore, only one field or one frame period of the video signal output from the video reproducing circuit 1 in the pulse period of the pulse S is extracted and output by the switch 2. When the pulse period of the pulse S ends, the switch 2 is switched to the P side, and the output signal of the video reproduction circuit 1 is cut off.

In this way, the control circuit 3 outputs the pulse S each time the count value becomes equal to the set value, and since this set value is equal to the number of video cameras used for recording, the same video camera on the magnetic tape is used. Only the reproduction signal from the track whose output is recorded is extracted and can be monitored.

Therefore, if you want to monitor only the output of the desired video camera, first, for example, still playback of the number of tracks equal to the number of video cameras is searched to find the track in which the output of this desired video camera is recorded. The above operation may be performed with this track as a reference.

2 is a block diagram showing an embodiment of the time lapse VTR according to the present invention, in which 4 is a switch, 5 is a video memory circuit, 5a is a memory, 5b is a write / read control circuit, and corresponds to FIG. The same reference numerals are given to the portions to be marked, and the explanation that attaches importance to them is omitted.

In FIG. 2, the switches 2 and 4 are normally closed on the P side, but when the pulse S is supplied, they are switched to the pulse period Q side. Therefore, only one field or one frame period of the video signal output from the video reproducing circuit 1 in the pulse period of the pulse S is extracted and output by the switches 2 and 4.

In the video memory circuit 5, the memory 5a is in the read mode by the write / read control circuit 5b, but when the pulse S is supplied, the memory 5a is in the write mode by the write / read control circuit 5b during this pulse period and the switch The video signal of one field or one frame period extracted in 2 is written in the memory 5a.

When the pulse period of the pulse S ends, the switches 2 and 4 are set to P
And the write / read control circuit 5b puts the memory 5a in the read mode. The written video signal of one field or one frame is repeatedly read from the memory 5a, and this video signal is output via the switch 4.

By such an operation, only the reproduction signal from the track on which the output of the same video camera on the magnetic tape is recorded is obtained, and during the period during which the track on which the output of another video camera is recorded is reproduced and scanned, the reproduction signal from the memory 5a The read video signal is output. Therefore, in the embodiment shown in FIG. 1, the output of the desired video camera is obtained as an intermittent signal, but in the embodiment shown in FIG. 2, only the output of the same video camera is continuously obtained. The quality of the reproduced image becomes good. Further, the control circuit 3 counts the control pulse CTL reproduced from the magnetic tape at the timing immediately before the vertical synchronizing signal in the vertical blanking period of the reproduced video signal, whereby the pulse S for switching the switches 2 and 4 is generated. Therefore, the switching timing of the switches 2 and 4 is set to the video reproduction circuit 1
It comes immediately before the vertical synchronizing signal in the vertical blanking period of the video signal output from, and therefore, the switching noise generated in the switches 2 and 4 is not mixed in the vertical synchronizing signal.

FIG. 3 is a block diagram showing a modification of the embodiment shown in FIG. 2, in which 6 is a video memory circuit, 6a is a memory, and 6 is a memory.
Reference numeral b is a write / read control circuit, and the portions corresponding to those in FIG.

In this embodiment, two video memory circuits 5 and 6 are used to obtain the same effect as that of the embodiment shown in FIG.

In FIG. 3, when one of the video memory circuits 5 and 6 is in the read mode, the other is in a stopped state. Now, assuming that the video memory circuit 6 is in the read mode and the bidet memory circuit 5 is in a stopped state, the video signal is read from the memory 6a and output through the switch 4 closed on the P side.

When the pulse S is output from the control circuit 3, the write / read control circuit 5b of the video memory circuit 5 puts the memory 5a in the write mode, and the output signal of the video reproduction circuit 1 is written to the memory 5a. Memory 5a
When the writing of the video signal for one field or one frame is completed at the trailing edge of the pulse S, the memory 5a enters the reading mode, and the switch 4 is switched to the Q side at the same time. The read control circuit 6b stops reading from the memory 6a. Therefore, the video signal is repeatedly read from the memory 5a and output via the switch 4.

Next, when the control circuit 3 outputs the pulse S, the output signal of the video reproduction circuit 1 is written in the memory 6a for one field or one frame, and then the reading of the video signal is started in the memory 6a and the switch 4 is set to the P side. The memory 5a stops reading.

In this way, each time the track in which the output of the same video camera is recorded is started to be reproduced, the video memory circuit 5,
6 alternates writing and reading of video signals, whereby the output signals of the same video camera can be continuously obtained.

The embodiments of the present invention have been described above, but the present invention is not limited to these. For example, in FIG. 1, the video memory circuit as shown in FIGS. 2 and 3 may be used instead of the switch 2. In this case, when the number of video cameras used for recording is two, an intermittent video signal similar to that of the embodiment shown in FIG. 1 can be obtained, but when the algebra of the video cameras is large, Since the obtained video signal is lacking only when the video memory circuit is in the write mode, the reproduced image on the monitor is of the same quality as that of the almost continuous video signal.

〔The invention's effect〕

As described above, according to the present invention, even if the outputs of a plurality of video cameras are alternately recorded on the same magnetic tape, only the output of the desired video camera can be reproduced from the magnetic tape. Can be correctly and easily confirmed, and the switching timing of the switching means is directly set in the part other than the vertical synchronizing signal in the vertical blanking period by counting the reproduced control signals. The switching noise due to the switching of the switching means can be made outside the signal period of the vertical synchronizing signal without making it complicated.

[Brief description of drawings]

FIG. 1 is a block diagram showing the basic configuration of a time-lapse VTR according to the present invention, and FIGS. 2 and 3 are block diagrams showing an embodiment of the time-lapse VTR according to the present invention, respectively.
The figure shows the time-lapse V when using multiple video cameras.
It is a figure which shows the track on the magnetic tape by TR. 1 ... video reproduction circuit, 2 ... switch, 3 ... control circuit, 4 ... switch, 5, 6 ... video memory circuit.

Claims (1)

[Claims] 1. Outputs of n video cameras (where n is an integer of 2 or more) are sequentially switched every one field or one frame period, and one field or one frame is sequentially recorded on each track on a magnetic tape. In the time lapse VTR, the control signal reproduced from the magnetic tape is counted, and the control signal of one field or one frame period is calculated every time the control signals of the number of the period for reproducing and scanning n tracks are counted. Control means for outputting, storage means for sequentially storing the reproduction signal from the magnetic tape during the signal period of the control signal, and continuing to read out the reproduction signal stored during a period other than the signal period of the control signal; Signal period A signal read from the storage means for selecting the reproduction signal from the magnetic tape and for a period other than the signal period of the control signal. And a switch means for selecting, magnetic lapse VTR, characterized in that only the output of one desired video camera from the tape was reproducibly configuration.