JPS62295581A - Time lapse vtr - Google Patents

Abstract

PURPOSE:To reproduce only an output of a desired video camera by counting the number of tracks and extracting a reproducing signal from a magnetic tape by one field or one frame each every time the count reaches a value equal to the number of video cameras. CONSTITUTION:A control pulse CTL is recorded on a recording tape at each track and the pulse is fed to a control circuit 3, whicn counts the control pulse CTL and compares the count with a preset value. When the count is coincident with the setting value, a pulse S of the one field (or one frame period) width is outputted synchronously with the control pulse CTL and the count means of the control pulse CTL is reset. Thus, only the reproducing signal from the track recorded with the output of the same video camera on the magnetic tape is extracted and its monitor is attained.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] The present invention provides a time-lapse V suitable for crime prevention and monitoring purposes.
Regarding TR (video tape recorder).

[Conventional technology]

Conventionally, video tape recorders used for crime prevention and surveillance have intermittently extracted video signals one field (or frame) at a time from multiple fields (or frames), and recorded long-term i! 2. Description of the Related Art A time-lapse VTR is known.

For example, in the time-lapse VTR disclosed in Japanese Patent Application Laid-Open No. 58-62985, one field of video signal extracted from each of multiple fields (hereinafter, explained in units of fields) is recorded (hereinafter referred to as time-lapse video signal). When recording video signals continuously, the magnetic tape is run at the same speed as when recording video signals continuously (hereinafter referred to as normal recording), and during other periods the magnetic tape is stopped. The inclination angle and track pitch of the tracks formed on the tape are made to be the same as in normal recording.

As a result, when the magnetic tape is run at the same speed as normal recording and played back, the rotating magnetic head scans each track on the magnetic tape as it is, and the long-time phenomenon is compressed in time. Images will be obtained with good image quality and no noise bars.

When monitoring multiple locations at the same time, such as a sales floor,
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 location to be monitored, the outputs of these video cameras may be alternately switched by a switcher, and the output of this switcher may be recorded on a time-lapse VTR.

[Problem that the invention seeks to solve]

By the way, when recording is performed by switching the outputs of a plurality of video cameras in this way, tracks on which the outputs of different video cameras are recorded are arranged alternately on the magnetic tape. For example, as shown in FIG. 4, when two video cameras 7.8 are used and one field of video signal is recorded on one track in one recording on the magnetic tape 9, the track When the output of video camera 7 is recorded in CI-A, the next track C2-A
, the output of video camera 8 is added to the next track Cl.
The output of the video camera 7 is recorded in -H, and the output of the video camera 7 is recorded on every other track, and the output of the video camera 8 is recorded on every other track. Each will be recorded.

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

SUMMARY OF THE INVENTION An object of the present invention is to provide a time-lapse VTR capable of reproducing only the output of a desired video camera from a magnetic tape on which the 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 the tracks on the magnetic tape when playing back the magnetic tape, and every time the counted value becomes equal to the number of video cameras, the playback signal from the magnetic tape is output. is configured to extract one field or one frame at a time.

[Effect]

When at least one track in which the output of a desired video camera is recorded on the magnetic tape is detected, reproduction signals of every other track equal to the number of video cameras are extracted with this track as a reference. These tracks are recordings of the output of the desired video camera, and therefore only the output of the desired video camera can be played back.

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

〔Example〕

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

FIG. 1 is a block diagram showing an embodiment of a time-lapse VTR according to the present invention, in which 1 is a video playback 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 reproduction circuit l.

On the other hand, a control pulse CTL is recorded for each track on the magnetic tape, and this is reproduced together with the video signal. This control pulse CTL is supplied to the control circuit 3.

The core)0-)Lt circuit 3 receives this control pulse C.
TL is counted and the counted value is compared with a preset value. This setting value is equal to the number of video cameras used for recording, and when the count value matches this setting value, the control circuit 3 controls the width of the field (or one frame period) in phase synchronization with the control pulse CT L. In addition to outputting the pulse S of , the control pulse CTI
, reset the counting means of . Therefore, the control circuit 3 outputs the pulse S every time the count value of the control pulse CTL becomes equal to the set value. This pulse S is supplied to switch 2.

The switch 2 is normally closed to the P side, but when the pulse S is supplied, it switches to the Q side for the pulse period. Therefore, only one field or one frame period of the video signal output from the video reproduction circuit 1 during the pulse period of the pulse S is extracted by the switch 2 and output. Pulse S
When the pulse period 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 a pulse S every 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 number on the magnetic tape is Only the playback signal from the track where the output of the video camera was recorded is extracted and can be monitored.

Therefore, if you want to monitor only the output of a desired video camera, first, for example, play back still tracks equal to the number of video cameras and search for the track in which the output of this desired video camera was recorded. The above operations may be performed using this track as a reference.

FIG. 2 is a block diagram showing another 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, and 5b is a write/continue control circuit. The same reference numerals are given to corresponding parts, and duplicate explanations will be omitted.

In FIG. 2, switches 2 and 4 are normally closed to the P side, but when a pulse S is supplied, they are switched to the Q side for the pulse period. Therefore, only one field or one frame period of the video signal output from the video reproduction circuit 1 during the pulse period of the pulse S is extracted and outputted by the switch 2.4.

In the video memory circuit 5, the memory 5a is in the read mode by the write/continue control circuit 5b, but when the pulse S is supplied, the memo IJ 5a is in the write mode by the write/continue control circuit 5b during this pulse period. mode, and 1 field extracted by switch 2 or 1
A video signal for a frame period is written into the memory 5a.

When the pulse period of pulse S ends, switch 2゜4 switches to Q.
Furthermore, the memory 5a is placed in the read mode by the write/continuation control circuit 5b. One field or one frame of written video signal is repeatedly read out from the memory 5a, and this video signal is outputted via the switch 4.

With this operation, only the reproduction signal from the track where the output of the same video camera is recorded on the magnetic tape is obtained, and during the period when the track where the output of the other video camera is recorded is being reproduced and scanned, the reproduction signal is obtained 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 obtained continuously, The quality of the reproduced image becomes better.

FIG. 3 is a block diagram showing still another embodiment of the time-lapse VTR according to the present invention, in which 6 is a video memory circuit, 6a is a memory, and 6b is a write/continue control circuit. Corresponding parts are given the same reference numerals and redundant explanations will be omitted.

This embodiment uses two video memory circuits 5.6 to achieve the same effect as the embodiment shown in FIG.

In FIG. 3, when one of the video memory circuits 5 and 6 is in a read mode, the other is in a stopped state. Now, assuming that the video memory circuit 6 is in the read mode and the video memory circuit 5 is in a stopped state, a video signal is read out from the memory 6a and outputted via the switch 4 which is closed to the P side.

When the pulse S is output from the control circuit 3, in the video memory circuit 5, the memory 5a is placed in a write mode by the write/continue control circuit 5b, and the output signal of the video reproduction circuit 1 is written into the memory 5a. Memory 5a
When the writing of one field or one frame worth of video signal is completed, the memory 5a enters the read mode at the trailing edge of the pulse S, and at the same time, the switch 4 is switched to the Q side, and the video memory circuit 6 performs the write/write mode. The memory 6a stops reading by the continuation control circuit 6b. Therefore, the video signal is repeatedly read out from the memory 5a and outputted 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 into the memory 6a for one field or one frame, and then 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 a track in which the output of the same video camera is recorded starts playing, the video memory circuit 5.
6 alternates the writing and reading of video signals, so that output signals from the same video camera can be obtained continuously.

Although the present invention has been described in detail above, the present invention is not limited thereto. For example, in FIG. 1, switch 2 is replaced by FIG.

A video memory circuit as shown in FIG. 3 may also be used. In this case, if two video cameras are used for recording, an intermittent video signal similar to the embodiment shown in FIG. 1 can be obtained, but if there are many video cameras, Since the resulting video signal is absent only when the video memory circuit is in write mode, the quality of the reproduced image on the monitor is almost as good as that of a continuous video signal.

〔Effect of the invention〕

As explained 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 played back from the magnetic tape, and the recorded content be able to recognize correctly and easily.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the time-lapse VTR according to the present invention, and FIGS. 2 and 3 are block diagrams showing other embodiments of the time-lapse VTR according to the present invention, respectively.
FIG. 4 is a diagram showing tracks on a magnetic tape produced by a time-lapse VTR using a plurality of video cameras. 1... Video playback circuit, 2... Switch, 3...
Control circuit, 4... switch, 5, 6... video memory circuit. Fig. 1 Fig. 2 Shop-111'' ← Hi 3 Fig. 3 Fig. 4

Claims (1)

[Claims] 1. In a time-lapse VTR in which the outputs of a plurality of video cameras are switched at predetermined time intervals and recorded on a magnetic tape one field or one frame at a time, the tracks on the magnetic tape are a first means for counting the number of video cameras and outputting a signal for each count equal to the number of video cameras; and a second means for extracting a reproduced signal from the magnetic tape by the first means for one field or one frame period at a time.
1. A time-lapse VTR, comprising means for reproducing only the output of a desired video camera from the magnetic tape. 2. In claim 1, the second means is a first switch to which the reproduction signal of the magnetic tape is supplied and is turned on for one field or one frame period by the output of the first means. a memory for repeatedly reading out the reproduced signal written during the on-period of the first switch and written during the off-period of the first switch; and a second memory for selecting the output signal of the first switch and the output signal of the memory. 1. A time-lapse VTR comprising a switch, and configured to output the extracted reproduced signal as a continuous signal.